Yes.

During and after WW2 several aircraft were converted to serve as "Dumbo" aircraft, dropping boats or rafts near people in distress.

Other models were used as well, but the B-17 were among the most prominent.

Most were retired when the helicopter gradually took over rescue operations.

It is quite common for float planes to carry canoes & kayaks, e.g.

Large enough helicopters do it.

Above example is a Boeing CH-47 Chinook ( businessinsider.com )

But since you have tagged it seaplane , not to my knowledge.

It's often the other way around, seaplane tenders tending to seaplanes (or used to).

(I take it by boat

you don't mean the inflatable and/or small type, as those are not hard to transport.)

Catalina launching beaching gear ( pinterest.com )

I would like to suggest the "Landseaire" flying yacht which carried boats under the wings as per this question.

It was one of the main roles for the Vickers Warwick in WWII.

From Wikipedia: From 1943, Warwicks were loaded with the 1,700 lb (770 kg)

Mk IA airborne lifeboat and used for air-sea rescue.

The lifeboat, designed by yachtsman Uffa Fox, laden with supplies and powered by two 4 hp (3.0 kW) motors, was aimed with a bombsight near to ditched air crew and dropped by parachute into the sea from an altitude of about 700 ft (210 m).[36]

Warwicks were credited with rescuing crews from Halifaxes, Lancasters, Wellingtons and B-17 Flying Fortress, and during Operation Market Garden, from Hamilcar gliders, all of which ditched in the English Channel or North Sea.[37] More on airborne lifeboats...

(also source for image above)

Of course, many WWII bombers carried inflatable dinghies, but I think the answer is looking for something more substantial.

The Fernic T-9 of 1929 was prepared for an Atlantic crossing and as a precaution had removable upper engine nacelles which could double as a life raft, including an outboard engine.

A less planned use of an airplane part as a boat occurred when in 1932 the Junkers W-33 of Hans Bertram and Adolf Klausmann crashed in a remote part of Western Australia.

They removed one of the floats and made it into a boat for fishing and excursions.

Took me a while to find this photo, from my personal archive from the East Fortune Airshow 2015 of a Royal Norwegian Airforce Lockheed Orion.

As I recall, the commentator stated that the orange object visible in the 'bomb bay' is an air-droppable lifeboat, for their search-and-rescue missions.

The Boeing C-17 Globemaster III can deploy boats.

There are some videos on YouTube ( example ) that show the process:

Question: A small boat could be part of general cargo, but that would typically just mean it's unloaded at an airport and transported to the nearest body of water by land infrastructure. This is not what I'm looking for.  Instead, is there any aircraft that can directly deploy a boat to (or retrieve one from) water?  I would imagine there are cases when moving a boat by plane could be useful, especially when there's little or no infrastructure available on land.  Does such an aircraft exist?

Do any aircraft carry boats?

aviation.stackexchange.com/users/42832/SE - stop firing the good guys

During WW2 many planes carried boats for various purposes. The Boeing C-17 can also deploy boats. Moreover, it is quite common for float planes to carry canoes and kayaks. Finally, large helicopters also can carry boats.

There are aircraft that can carry boats; at the time of the 2nd World War many models did it, mainly B-17 or the  Vickers Warwick. The "Landseaire"  also served that purpose and even the Boeing C-17 Globemaster III can deploy boats. Also, float planes often carry small boats like canoes, etc. It must be noted that large helicopters are used for this task as well.

Float planes often carry small boats like canoes, etc.

Large helicopters are used for this task.


Their primary wing feathers have an unusual structure incorporating a fringed, comblike leading-edge, which reduces wind noise.

The wing feathers also have an overall softness or flexibility.

The trailing-edge of the wing is also dominated by soft, fringed edges.

Even the underwing lining (covert) feathers have an unusual softness that plays a role in sound suppression.

See for example --

https://www.owlpages.com/owls/articles.php?a=7n , https://animals.howstuffworks.com/birds/owl-fly-silently1.htm .Google "owl feather structure" for more.

I'll leave it mostly unsaid, as to whether any of these features are worth incorporating into a jet-powered aircraft.

Maybe some of these features might be applied to the intake or exhaust areas, in a more rigid metallic form?

In addition to quiet flyer's excellent answer: Owls have large wings in relation to their body size and weight.

One might think that no, their bodies are quite large, but actually owls are kind of fluffy flying feather balls: what you percieve as their bodies, is mostly air.

This leads to two things: Low wing loading.

Their large wings do not need to create as much lift per area unit as, say, with pigeons.

This leads to less turbulence, which in turn means less sound.

Because of low wing loading they also can fly with very little wing movement, also leading to less sound generation.

The fluffyness (for lack of a better word) suppresses turbulence in wing - body attachment area, and any other turbulence around owl body.

This means, of course, less sound.

When combined with wing structure described in q f's answer, all these factors create a pretty much absolutely silent flight.

Check out this excellent BBC Earth clip comparing

the sound different birds make when they fly, and why so.

As for the aplicability of these features in stealth aircraft, not likely, athough I strongly second PerlDuck's vote for fur covered wings on aircraft.

The fact is, however, that there is no sense in making the wings or the airframe more silent, when the sound of the propulsion is orders of magnitude louder than any other part of the aircraft.

P.S.

It's actually quite eery to encounter an owl in flight when it's dark.

You can hear other birds when they fly in your vicinity, but owls, no

, they just blast right by you totally silently, without a warning.

They've scared me sh__less a couple of times out in the wild, and I'm pretty sure they enjoy it...

Stealth aircraft are built to reduce their observability in 3 main areas, with the goal of reducing the warning time an enemy has: radar optical and IR

sound

This is in order of detection range:

Radar can find an aircraft potentially at hundreds of km, optical systems go to a few tens of km, and sound becomes a factor only when the aircraft is very near (at low altitude and high speed, you can get within 100 m of the target before you become audible).

The detection range also gives you the order of importance.

Radar takes priority.

The sound produced by an aircraft is dominated by its engine noise.

The air rushing over the skin makes some noise, but that's generally only audible when the engines are shut off.

This means there's no benefit to reducing skin noise.

In addition: a fringed, comblike leading-edge

This is a nightmare for radar stealth.

You want the structure to be as simple and smooth as possible, because when you have a large number of surfaces in many directions, you get many radar returns.

Improving audio stealth would compromise radar stealth.

Owls' bodies are optimised for silent unpowered flight;

even when owl flight is powered flight, it's powered by wing flapping (rather than jet engines or turboprops).

At most I suspect you'll be able to help silence the noise from a body passing through the air; as gliders are rather quieter than light aircraft, I suspect this is the minority of the sound, at least until speeds get very fast where the aerodynamic and acoustic models will be very different anyway.

However, as "aircraft" is widely defined, perhaps they would be useful for a drone that for portions of its flight mostly glides silently at low-ish (owl-like) speeds, for covert photography, covert small payload delivery, or some other likely nefarious purpose.

Heck, it could actually be disguised visually as an owl.

If the other excellent answers roll off you like water off a duck 's back, this may convince you: What owls had to give up in exchange for quieter (not silent!)

flight, is fast flying and flying on rainy days.

Their feathers miss (most of) the oils that make other flying birds able to take quite a drenching without much trouble (and water birds even more so).

Planes crashing because of wet wings would be frowned upon, of course --- but the fixed wings would not have that problem; however any moisture would defeat this noise reduction.

Only during landing & take-off noise reduction is really wanted (cruising altitude is too high to care); the added drag throughout the flight is (and added weight+drag when wet during takeoff+landing) will surely rule it out.

However, you can consider applications where it would be justified : If there's a large premium for silence, no need for high speed?

Sounds like e.g. a specialized drone for observations to me.

Then: If it's raining, take out the regular spy-drone (as the rain covers the drone noise); if it's dry, your special 'owl-drone' goes out...

This more or less doubles your cost-of-ownership as you need two not one drone.

Question: I was wondering about the ability of owls to fly so silently. Is it because they flap gently, they flap less often or do is their structure responsible? I was thinking their principle of stalking can be applied to stealth aircraft. Is it possible?

Could the principle of owls' silent flight be used for stealth aircraft?

S12: Owls' bodies are optimised for silent  unpowered  flight. The fact is, however, that there is no sense in making the wings or the airframe more silent, when the sound of the propulsion is orders of magnitude louder than any other part of the aircraft.  However, as "aircraft" is widely defined, perhaps they would be useful for a drone that for portions of its flight mostly glides silently at low-ish (owl-like) speeds, for covert photography, covert small payload delivery, or some other likely nefarious purpose.

The feathers and overall "fluffy" wings of the owl are perfect for silent flight because they supress turbulence and noise. Owls are optimized for this type of flight. As for the application of the owl's characteristics to an aircraft, it would not be practical to do so. Perhaps it would be useful for drones that need to be silent but not necessarily very quick.


Not only is it possible but it happens.

This is formally called a "runway incursion" and it does happen like 2005 Logan Airport runway incursion or the B733 / vehicle, Amsterdam Netherlands, 2010 .

Skybrary has a full list you can find here which is quite lengthy and includes a full section for Vehicle Incursion .

In 1978 a B737 aborted a landing due to a snow plow on the runway.

The aircraft crashed during the go around because one thrust reverser did not stow properly.

Yes.

I was on final once when a taildragger in front of suddenly turned around to backtaxi and turn off on the taxiway he had just passed, thinking to do me a favor and get off the runway quicker.

Unfortunately, I had been catching up to him on final anyway, so I just powered up and went around.

If you don't quite abort... Plane Collides with SUV While Landing at (Texas)

Northwest Regional Airport (52F)

I can remember one evening quite some years ago when there was a sudden extremely loud noise.

Not quite an explosion -- much too protracted and no shock, but you get the general idea.

Since there was no flying debris, no visible columns of smoke, no sign of anything else out of the ordinary, I ignored it apart from paying more attention to the news that evening.

The news reported that Concorde had aborted a landing at Heathrow because somebody had strayed onto its runway.

This required afterburners!

The emergency services lines closer to Heathrow were jammed for quite some time, with people trying to report the "explosion".

I personally witnessed one at EWR (Newark International).

The runways in EWR run parallel to New Jersey Turnpike, only meters away.

I was driving on NJ Turnpike northbound when a flight (looked like a B737, but

I'm not sure) touched down parallel to

the I-95 just at my level and moments later powered up and went around.

A few more moments later I noticed another, much smaller, plane further along the same runway.

This was in 1998 or 1999.

I am but a meager low time private pilot, but I'm sure this happens all the time as it has happened to me.

Before I got my certificate, I departed my home (towered) airport solo planning to buzz over to a nearby very small uncontrolled airport and practice some landings.

When I arrived, the city mower was working around the runway, apparently not listening to CTAF.

I aborted the first landing as he crossed the runway just in front of me.

Fortunately, he was just finishing the area around the runway

and I was able to continue practicing without any further issue.

From a safety standpoint, it was never a big deal.

I saw the mower, was aware of his location, and watched to see if he would depart the area before I got close to the ground.

He didn't, so I performed a go around.

I was surprised that he seemed not to notice me, but it was more inconvenient than unsafe.

On my first flight I flew into LAX and we were coming into land and suddenly went up again.

Looking out of the window and there was another plane on the runway.

The captain confirmed over the intercom that was the reason for the aborted landing.

I would guess this was in 1977.

Question: I came across a fake video of an A380 closely avoiding a fuel truck. More details at  Snopes  including a link to the YouTube video.  While this video is not real, I'm interested in finding out if it's a realistic situation and if there are any real instances where accidents have been avoided because crew decided to abort takeoff or landing as a result of an unexpected runway intrusion as seen in the video.

Are there any real life instances of aircraft aborting a takeoff or landing to avoid a vehicle?

It is not onlythat a plane aborts a landing for a vehicle on the runway but it happens. This is formally called a  "runway incursion"  and it does happen like  in 2005 Logan Airport runway incursion  or the  B733 / vehicle, Amsterdam Netherlands, 2010 . In 1978 a B737 aborted a landing due to a snow plow on the runway.

This has indeed happened numerous times and many people report having seen/done it, under various conditions with the main problem being another vehicle being an obstacle to their landing.


They are both internal combustion engines that have a turbine in their exhaust that is used to power a compressor to pressurize the air before it is used for combustion.

In the turboprop, the turbine also powers the prop.

In between the compressor and turbine, the fuel/air mixture is burnt without significant moving parts.

Without the turbine and compressor, a turbine engine is essentially a tube with heating element in it.

In a turbocharged piston engine, you have an otherwise normal piston engine which turns the prop.

The turbine is in the exhaust from the piston engine and powers the compressor pushing air into the piston engine.

The turbine and compressor are not connected to the prop though.

Here they are as diagrams along with some other types of engine.

No, a turboprop is more like a jet engine with a propeller in the front instead of a fan: Source:

Wikimedia

In its simplest form a turboprop consists of an intake, compressor, combustor, turbine, and a propelling nozzle.

Air is drawn into the intake and compressed by the compressor.

Many turbo props have a gear box (as shown in the image above, the black part to the left) which drives the prop from the engine.

Whereas a turbo piston is simply a normal piston engine with a turbo charger attached:

Source:

BoldMethod

You can learn more about how a turbo piston works on BoldMethod: How a turbocharger system works .

The basics is that it uses the exhaust gases from the engine to drive a compressor which increases the pressure (and oxygen content) going into the intake.

More oxygen (and fuel) means more power.

For turbo-pistons it also means that you can get sea-level performance at altitude.

As far as fuel is concerned, a turboprop runs off of Jet-A (Kerosene) fuels and (most)

turbo charged pistons run on av-gas.

Some diesel turbo pistons also run off of Jet-A and it is very important that you don't put Jet-A in an av-gas piston or av-gas in a turbo prop.

A turbocharged engine is a common gas engine with pistons

The limiting factor on a gas engine is how much air can get into the pistons.

It is supercharged - that is, an air pump forces more air into the engine than it would draw naturally.

The mechanically driven variety is seen on Mad Max .

If you use exhaust flow to spin the pump, it is turbo supercharged.

People shorten "turbosupercharge" to "turbocharge".

A turboprop engine is a jet engine.

Fullstop.

The jet engine makes lots of thrust.

They stuck some extra turbine blades in the jet blast, which spin another shaft.

That makes it a "turboshaft engine" because it makes rotation instead of thrust.

You put something useful on that shaft, like a generator , helicopter rotor , naval screw , air compressor , fan , propfan , or in this case, a prop.

That's a turboprop!

The advantage of a jet-based instead of piston-based engine is power-to-weight - after all you have nominally 2 moving parts, the spindle of the jet engine

proper and the added turboshaft, and nothing reciprocates.

aviation.stackexchange.com/users/22864/Harper - Reinstate Monica

They are completely different things, a turboprop is similar to a jet engine as it has compressors, the main difference is that there's a shaft that spins a propeller instead of turning a fan.

A turbocharger is device for piston engines, it uses pressure coming from the exhaust manifold of a piston engine to compress air going into the intake manifold.

It's the same technology used on car diesel and gasoline engines, and it works the same way.

There are vanes that can be adjusted to manage the boost level, on cars these are computer controlled but in many airplanes turbo speeds are have to be manually adjusted by adjusting boost pressure in the exhaust (keyword: wastegate).

Recent aero-diesels have modern computer controls though.

Turbos on piston aero engines can either be turbochargers, in which case they add extra power to an engine by increasing the compression in the cylinders, or they can be turbo-normalizers, which maintain sea level air pressure to the engine even at higher altitudes.

There are superchargers as well, these are also compressors for piston engines

the difference is they use engine power directly to compress the air rather than exhaust pressure.

No, one is https://en.wikipedia.org/wiki/Otto_cycle one is https://en.wikipedia.org/wiki/Brayton_cycle , thermodynamicly extremely different

Question: Simple question, and I've always assumed that they are the same thing, but I'd like feedback from someone who knows more than me :)

Is a turbocharged piston aircraft the same thing as turboprop?

They are both internal combustion engines, however, they are completely different things, a turboprop is similar to a jet engine as it has compressors, the main difference is that there's a shaft that spins a propeller instead of turning a fan.

They are both considered internal combustion engines with a turbine in their exhaust that powers a compressor and pressurizes the air before its use in the combustion process. That said, they are totally different things, with turboprop being essentially a jet engine and the main difference being if a shaft is spinning the propeller or a fan.

They are totally different things, with turboprop being essentially a jet engine and the main difference being if a shaft is spinning the propeller or a fan.


This is borderline as an aviation question but I will answer it anyway.

They didn't use those weapons because they did not have them at the time:

Conventional cruise missiles did exist but most were nuclear, and the UK didn't possess any conventional ones.

ICBMs with conventional warheads

did not and probably still do not exist because they are not a good idea:

Their capacity is low: A sub launched ICBM has somewhere around 2.5 to 3 metric tons' throw weight, much of that would be taken up by warhead guidance, thermal protection and other necessities

so your actual warhead would be maybe 1000kg, or 2200lb.

That's not that big a conventional bomb, and it could only launch one.

A fighter bomber could drop 2 of those.

The Vulcan bombers on the raid carried 21 1000 pound bombs.

They aren't accurate enough: a nuclear weapon can be a bit off and still destroy its target utterly, a conventional weapon needs a great deal of precision.

The Polaris missile had an accuracy of 3000ft (900m).

That's okay for a nuke, it' still ruin someone's day, but completely inadequate for a 2000lb bomb.

More modern ICMBs have more like a 100 meter accuracy, which is a lot closer but still not good enough for a conventional bomb

They are expensive: that's a lot of cash for a 2000lb bomb that probably will miss Launching one

could start

WW3 : If you launch an ICBM someone is going to see it and

if they think it might be directed at them a retaliatory strike could be the answer.

The world has come perilously close to this more than once, it simply isn't worth the risk!

Because all of Britain's adversaries were either nearby (Warsaw Pact) or too far to economically fight (China).

Since Britain's weapons only needed to reach the Caucasus, they simply never developed ultra-long-range assets like the Tu-95 Bear or B-52 Stratofortress.

Unfortunately no-one was willing to provide any of those under Lend-Lease.

Honestly, even if the British had appropriate cruise missiles (they did not), they would have no reason to own ones with the range to hit the Falklands from Ascension.

Nor would they have any reason to need ICBMs with the range to hit Falklands from the UK

(they wouldn't have ICBMs in Ascension, who would they nuke?

The Congo?

Guyana?)

Again the enemy is in Europe, so everything is sized and positioned to go just that far.

Your question takes for granted the pre-existence of weapons systems like the "down a chimney" Tomahawk.

Honestly, the British inability to do anything but have their SSN crews shake their fists at the islands, was a major impetus in developing those new families of weapons.

Every major force watched with keen interest and thought "

Gosh, what if we had to deal with one of these?

However, they certainly did have relevant weapons:

Aircraft carriers.

This type of mission is the reason carriers exist.

They could project power from the Spratleys to, indeed, the Falklands.

Further, there'd be little point to using cruise missiles or ICBMs before

the main force was in position to make good on the advantage.

And once the main force was in place, they could strike from there, and did not need long-range weapons.

aviation.stackexchange.com/users/22864/Harper - Reinstate Monica

The UK needed a surgical strike to neutralize the Port Stanley airport in the Falklands so that Argentine airplanes based there couldn't attack the coming UK convoy or the impending UK ground attack.

An attack by carrier airplanes wouldn't work because the carriers, and the accompanying task force, would also be in range of the Argentine planes based in Port Stanley.

Using nukes against the airport at Port Stanley would have destroyed Port Stanley and all the UK citizens there.

This hasn't been explicitly said, so: The UK didn't have cruise missiles or ICBMs with conventional warheads at the time.

The Trident II D5, the UK's only ever ICBM, entered service in 1994: BBC .

As for cruise missiles, the BGM-109 Tomahawk has been introduced in 1983 (US) and 1998 (UK): Royal Navy .

Someone mentioned the harrier wasn't able to carry a bomb heavy enough to crater the runway.

The Vulcan's dropped 21x1000lb bombs on the Falklands.

The Harriers in the Falklands dropped 1000lb paveways (Laser guided).

They could carry 2 normally perhaps even up to 4.

So they could and did drop the same size of bomb, probably more accurately.

Though there was radar controlled guns and SAM that would have been made it very hazadous for low flying aircraft.

Though the harriers did raid the airport on occasion.

Some of have suggested there was inter service political rivalry.

The Vulcan raid was a another means for the RAF to contribute to the war.

Though the Harrier GR3 pilots were RAF.

It was probably a combination of a lot of these factors.

Question: There is a lot of information about this complex operation. But can anybody explain why they chose to use an aircraft? They could easily shoot cruise missiles from a ship or ballistic missiles from a nuclear submarine. The easiest and quickest option would be just to shoot an ICBM directly from the UK using a conventional warhead. Just put the coordinates in and task done. No risk to anyone! I think the UK had all the needed technology by that time.

Why was the Vulcan bomber used for the Falklands raid?

The British did not have cruise missiles with conventional warheads at the time of the Falklands war. They couldn't use nuclear warheads which would have killed all the British citizens in Port Stanley so they used to most appropriate bomb available.

The main reason they did not use conventional cruise missiles, nuclear weapons was that they did not exist at the time or the UK did not possess them for that range and also because the position of Britain's adversaries did not permit it. They did drop a bomb of the same size with accuracy, but the truth is that neither a carrier attack, nor a nuclear strike would work because the first would be shot down and the second would have tremendous consequences for the area.

The main reason they did not use conventional cruise missiles, nuclear weapons was that they did not exist at the time or the UK did not possess them for that range.

They dropped a bomb of the same size with accuracy.

Because the position of Britain's adversaries did not permit it.

Neither a carrier attack, nor a nuclear strike would work because the first would be shot down and the second would have tremendous consequences for the area.


The small wings make it fly like a brick.

Without the wings it would fly like a stone.

Seriously, you are taking the expression too literally.

The Space Shuttle is landing like a glider plane with a (not so good) glide ratio of about 4.5:1 (see What was the Space Shuttle's glide ratio? ).

No brick would be able to achieve that.

Designing the Space Shuttle as a lifting body ( ≠ brick) was actually considered.

It appears that a lifting body design was not able to comply with the flight envelope requirements.

As everyone has pointed out, it's a joke.

Others have answered the lifting-body question (it didn't meet design requirements), so I just wanted to expand some thoughts on the spirit of the "flying brick" nickname.

I suspect whoever came up with the term didn't spend a lot of time analyzing it.

However, I think it's significant that the nickname is flying brick - not falling brick.

It doesn't imply that the shuttle doesn't have wings or can't fly.

Instead, it implies that the vehicle has blunt and non-smooth surfaces which creates tremendous drag (like a brick) and limits its glide ratio.

For my talk on how to land the space shuttle, I created this visual, which I think captures the spirit of the nickname: Unfortunately, even though I think you knew this was a joke, a lot of people take jokes and analogies too seriously and turn them into conspiracy theories.

I get lots of comments on my talk from people who think that, if the shuttle flies like a brick, it can't possibly be a glider and therefore...

space is fake.

♂ (/facepalm)

So... I don't think having serious answers to a question like this is a bad thing.

In addition to its poor glide ratio the shuttles name also stems from the materials its made from as much as it does its poor glide performance.

The Space Shuttle's heat shield was made out of LI-900 Silica tiles that strongly resemble bricks and thus the shuttle was sometimes called the "Flying Brickyard" .

If you would like to know why NASA chose a wing design over another capsule or lifting body they actually published an explanation here as to their choices.

In short it was a mix of socio-political pressures and old school "airplane" mentality where many of the engineers came from, a large chunk of Air Force requirements driving the original designs and hard engineering reasons that lead to the Delta Wing vehicle that was ultimately built.

In response to the other portion of your question, A lifting body could be used and that is basically the design of Sierra Nevada Corporation's new Dream Chaser .

"Flies like a brick" is merely a figure of speech.

It comes from personal feelings of the pilot when comparing it to an actual plane.

It's just like the saying that someone is "dumb as a rock".

Obviously, even the most stupid person (or even animal) is much smarter than rock.

The saying merely expresses the frustration of the speaker when dealing with a person that stupid.

"Flies like a brick" was coined most likely because of combination of its abysmal glide ratio (1:1 at its worst, 4.5:1 at it's best) with simultaneous (and counter-intuitive) reliance on it.

Compare it to a 747 which has quite poor glide ratio of 17:1 and it's not supposed to glide.

Sailplanes have over 50:1, so that's the kind of performance a sane person would expect from a vehicle that's meant to do nothing but glide.

An actual brick has glide ratio of about 1:10.

In fact, the Space Shuttle flies more like the best sailplanes (11× difference) than like a brick (45× difference).

Surprisingly, it's marginally better than Concorde at take-off (4:1), but not at speed (12:1).

I couldn't find the glide ratio of an X-24, but it must have been considerably better than 1:1 (to be considered flying instead of falling), so that's still more than 10× better than a brick.

Adding to other answers, yes space shuttle is a brick that flying not just a brick.

Body-lifting can not be disregarded in hypersonic flight during the reentry, it is not just the wing creating the lift, it is the whole bottom section hitting the atmosphere.

Looking at another famous spacecraft, Appollo, it doesn't have any conventional wings but NASA uses only CG shift and altitude control to achieve atmosphere skipping because the body lifting from its bottom side.

This documentary explains how it is done: The wing also gives the shuttle huge landing flexibility, or what called the "cross-range" which brings to my third point.

Changing direction in orbit takes a crazy amount of energy and in orbit, you are on "rail" sort of speak.

The Earth rotates below you and to return you have to wait until you got a close passage across your landing site.

However, with Shuttle's relative big wings, it has a huge of cross-range(it is actually a design goal originally from the Air Force), the shuttle can make big direction change during reentry just like a normal airplane.

It has about 1100 nautical miles in cross-range, which means the closest approach to Cape Canaveral could be as far out as in the middle of the Atlantic Ocean and still be able to glide back.

Question: I have seen the Shuttle named a "flying brick" multiple times.  However a brick, as understood in the building industry, is a simple rectangular shape without wings and without any adaptation of the form. If the Shuttle was only capable of that much, why could not it be a lifting body like  Martin Aircraft X-24?

If Space Shuttle flies "like a brick", why does it need the wings?

Flies like a brick was not meant to be taken literally, it was coined most likely because of combination of its abysmal glide ratio (1:1 at its worst, 4.5:1 at it's best) with simultaneous (and counter-intuitive) reliance on it. In addition, the Space Shuttle's heat shield was made out of  LI-900 Silica tiles  that strongly  resemble bricks  and thus the shuttle was sometimes called the  "Flying Brickyard" .

"Flies like a brick" is a figure of speech and should not be taken literally. They reason this expression is common is because the Space Shuttle has a really bad glide ratio, to which it relies a lot, thus making it "fly like a brick". Another reason is that the material of the Space Shuttle resembles bricks.

The material of the Space Shuttle resembles bricks.


This PDF indicates an increase by ~10 dB for an F-8K in afterburner versus the same aircraft in 100% dry thrust.

This PDF indicates smaller increases: +5 dB for an F-15 +4 dB for F-22 and F-35

It has been around 20 years since I've been on a carrier deck, but I recall that it wasn't as dramatic of an increase as you might think.

It may have gotten a little bit louder, but what I remember more is that the tone changed.

The sound was more "full" when the afterburner was engaged.

I realize this is a rather subjective answer.

I would say definitely yes, because of all the extra energy added to the exhaust flow and it's obvious to anyone who attended enough military airshows.

Watch an F-16 depart with reheat on, then reduce thrust to military power (max thrust with reheat off) on the climb out, and it almost sounds like the engine flamed out.

The flow out the nozzle may be just over mach at military power, but will be well over Mach 2 with reheat on.

The nozzle changes shape with afterburner to manage all the extra energy and pressure, from a straight convergent duct to a convergent/divergent duct, like a rocket exhaust bell.

Although he doesn't cover the noise issue, this video explains why the nozzle has to change shape to control the mass flow through the engine because of all the heat energy added (math warning to those put in a catatonic state by arcane formulae).

The extra sound that results is a given.

To explain if the afterburner makes the engine louder, you must understand what the afterburner does.

In the afterburner, the exhaust gases are re-heated by injecting fuel in the afterburner duct.

The left oxygen is used to burn the fuel, which results in an increased exhaust gas flow.

Note that the engine itself will not spool up faster: this is done by opening the exhaust nozzle; without opening the nozzle, the pressure would be too high and the fan would stall.

The extra gases leaving the engine produce a higher velocity jet stream; more mass and more velocity will yield more thrust, which is the purpose of afterburning fuel.

If you look at jet noise modelling , you will find that the formula to calculate the jet noise includes the exhaust velocity (to the power of 8), so increasing the fuel flow and increasing the velocity will also increase the noise production.

The referenced model has been implemented in our gas turbine simulation program and verified against the noise measurements of a fighter aircraft to find that this model perfectly agrees with the measurements.

From an energy standpoint, the engine produces heat, thrust, and less significantly, sound.

Ignore the afterburner for a second and just consider throttling up, whether a jet or your car.

The engine gets louder.

That's not a law of physics, that's just what happens.

There's no theoretical reason why the extra waste energy can't go 101% into heat, and -1% into sound (think of noise-cancelling headphones) or into sound at frequencies inaudible to the human ear.

But practical combustion engines get louder (both overall and to the human ear) as they burn fuel faster.

You would be surprised if throttling up made your engine quieter.

The same goes for increasing fuel burn via afterburner, only more so.

For one thing the afterburner is inefficient, so there is a higher proportion of waste energy to dissipate.

For another the afterburner noise happens later and is less controllable, even if there was any desire to do so.

Question: I would speculate that an afterburner increases the noise because it is nearer to the exhaust. But it certainly causes so many changes in the exhaust flow that it could be less loud as well. It may also depend on the shape of the nozzle.  That an afterburner increases the spacial volume of exhaust gases does not necessarily mean that the sound volume increases as well, because it strongly depends on the level of turbulence.  Does activating an afterburner make a jet engine louder? And why?

Is an afterburner louder than the same jet engine without it?

S0: I would say definitely yes, because of all the extra energy added to the exhaust flow and it's obvious to anyone who attended enough military airshows. It may get a little bit louder, but what is more noticeable is that the tone changes. If you look at  jet noise modelling , you will find that the formula to calculate the jet noise includes the exhaust velocity (to the power of 8), so increasing the fuel flow and increasing the velocity will also increase the noise production.

Scientifically speaking, the extra energy due to added fuel flow should produce extra noise. However, in practice that is subjective, and  it can be argued that there is only a small increase; the sound mainly changes in pitch.

It is subjective, but it can be argued that there is only a small increase; the sound mainly changes in pitch.


It's hugely unlikely.

Almost vanishingly unlikely, with few exceptions perhaps for something a little smaller than a passenger-carrying A380 (like a private jet on a repositioning flight where you know the captain well) You used to be able to go up and see the captain on the flight deck -

I did it a few times as a kid.

Even then asking to sit in the jump seat was usually met with a smirk.

And then 9-11 happened.

With effect from 1 November 2003, ICAO Annex 6 was amended so that under Chapter 13.2.2 “all passenger-carrying aeroplanes of a maximum certificated take-off mass in excess of 45 500 kg or with a passenger seating capacity greater than 60 shall be equipped with an approved flight crew

compartment door that is designed to resist penetration by small arms fire and grenade shrapnel, and to resist forcible intrusions by unauthorised persons.

This door shall be capable of being locked and unlocked from either pilot’s station”.

And with that came locking of the cockpit door, and no more visits to the cockpit during flight

(incidentally, if you ask nicely, the captain will often let kids take a peek when they're deplaning the passengers)

And then germanwings happened, and they had a rethink.

But still no visits to the cockpit during flight at all for the average Joe.

As a non-professional pilot, to get a ride in the cockpit jumpseat, you'd have to meet at least three conditions: company policy must allow passenger in jumpseat PIC must allow passenger in jumpseat you'd have to be well known and trusted person to either SIC or PIC (preferrably PIC) If you fail to meet any of those, no jumpseat ride for you.

So, very slim chances, but not impossible.

The aforementioned is based on personal experience, multiple occasions, and applies to a major intercontinental airline which I will not name.

I regrettably inform you that your chances are very slim, outside of actually completing the training required to fly the aircraft.

In this world where aircraft terrorism is always a concern, you would have to have a very good reason to convince the captain why he has to put a complete stranger in the cockpit.

To the captain, the stranger is simply someone claiming to have flight experience.

To the stranger, it may be an experience; to the captain, it is a routine, daily job, with schedules, policies and regulations to follow.

In my airline, this would be strictly against policy.

Even if we were to jumpseat a flight attendant, there has to a necessity to do so (e.g. no rooms in the cabin / broken seat etc.)

There are companies that provide simulator rides to the general public.

There are none that provide a jump seat ride as far as I've heard.

Disclaimer: I am not affiliated with the linked company.

I would suggest to purchase a training session for A320 in a certified flight simulator like this one , for instance.

I understand this is not a real flight, but these simulators feature full scale cockpits with all controls, and the realistic algorithms to simulate the flight itself.

A

after the instructor giving you an introduction, you will be able to take the controls yourself during take off.

This may work pretty well as a counter-measure against the fear of flying.

This is not really direct answer to the question 'as-is'.

It's more answer to '

how can a Non-Pilot' fly regularly in the jumpseat.

Just become Flight Dispatcher.

In many airlines that gives you 'Known Crew' badge.

And with it and PIC permission you can fly in the cockpit as much as you wish.

Dispatchers even trump flight attendands in that regard.

Regular jumpsitting is part of the work actually.

Some FDs just use it as a meaning of commute - in the US per ALPAs rules AFAIK.

The catch - in the EU

the training is 2000 EUR, the course requires you to pass 14 exams - the very same as for ATPL :D &

Question: A couple of years ago, I had a strong fear of flying. Now, I really enjoy it. In fact, it is a dream of mine to sit in  the jumpseat of an A320 during takeoff. I've had a handful of flying lessons.  If I took my logbook and explained my interest to the captain, is there any chance this could happen? If not, how could I make it happen?

How can I get a ride in the jump seat as a non-professional pilot?

It seems it is almost impossible for a passeneger to get a ride in the jumpseat in the cockpit. Most airlines would not permit this. The best option is to do it in a simulator.

While some would argue that there is no clear answer to the question in the way it is posed, the general consensus is that this is hugely unlikely to happen, as in order to be able to be inside the cockpit, due to the rise in terrorism, certain strict conditions must be met. The best solution is to experience this in a flight simulator.

This is hugely unlikely to happen, as in order to be able to be inside the cockpit, due to the rise in terrorism, certain strict conditions must be met.

There is no clear answer to the question in the way it is posed.


Yes it's called a Deep Stall , and is mostly a problem with T Tail aircraft, especially jets with Supercritical Airfoil wings (like the CRJ Regional Jet line).

Such wings stall from the leading edge and the stall's flow separation spreads rapidly and completely across the entire wing all at once, so there is very little residual nose down pitching moment.

Plus the T tail ends up in a spot where it's in the wake of the flow from the wing, and gets blanked out, and loses its ability to pitch the nose over with positive lift since it's sitting there in the turbulent wake of the wing.

So the plane just mushes downward in an unrecoverable, stabilized, well, mush, and will pancake into the ground like that.

A CRJ200 test aircraft was lost in development testing when it got into a deep stall and IIRC, the stall/spin recovery parachute in the tail failed to deploy (or it didn't have one at the time; I forget which).

Such airplanes require, in addition to the usual stick shaker, a stick pusher to force the nose over, by shoving the control column for you if you do nothing while the shaker is going off, before the natural stall can occur, since the natural stall can be unrecoverable.

Generally if an airplane has a stick pusher system it means it has a deep stall mode.

What you describe is a tailslide, as another answer has noted -- but there is a condition in which the wing is stalled and the normal recovery method (apply down elevator and wait for the nose to drop and airspeed to build) can't be used.

It's called a "deep stall" and is only a problem with certain layouts of flying surfaces.

One of the best known is a T-tail in which the spacing between wing and horizontal tail is such that it's possible for the turbulent wash from the stalled wing to completely blanket the stabilizer and elevators, making it impossible for those surfaces to overcome the drag pushing the nose up.

This can make a deep stall unrecoverable in certain T-tail aircraft (the F-104 was infamous for this, and it also affects some sailplanes).

Worthy of note is that deep stalls (commonly called a "falling leaf") were a common maneuver in the days of fabric covered biplanes; many of these had enough elevator authority to hold the stall, and enough rudder to keep the stall "straight ahead" rather than letting it turn into a spin.

They were used as an alternative to a slip, to dump altitude without letting airspeed increase excessively.

Most monoplane designs (that I'm familiar with) don't have enough pitch authority to hold a deep stall (part of making aircraft spin resistant is making them stall gently), so the maneuver has fallen out of general familiarity.

The difference between a controlled deep stall and an unrecoverable one is loss of pitch authority due to blanketing of the horizontal tail.

Yes.

Moving CG farther and farther back will eventually cause the plane to be directionally stable falling backwards.

Abusing rearward CG limits is contributory to this condition.

Secondly, poor design of horizontal stabilizer, particularly, lacking sufficient "weathervaning" area, will cause an aircraft to be more susceptible to the unrecoverable "deep stall".

With models, this is tested by holding the plane horizontal to the ground and releasing it with no forward motion.

The relative wind, being 90 degrees to the wing and tail, means they are both stalled, but the pitch torque from the DRAG on the horizontal stabilizer, the rear fuselage and the trailing edge of the wing should flip the nose down and unstall the plane.

Higher aspect wings and/or

a shorter fuselage requires greater tail area for the same pitch torque, AND, a larger weight to surface area ratio (bigger plane) also requires a greater tail/wing area ratio.

Placement of the all important horizontal stabilizer can also affect its performance.

If it is in the "shadow" of the wing, as with T tails, a very high angle of attack can limit its ability to create pitch down torque.

Downwash from the wing can also affect a "low" Hstab.

Lengthening the fuselage is a remedy for not only wing airflow effects, but also increases the pitch torquing lever arm of the aircraft, enabling the same size Hstab to be more effective.

Thrust angling is also a key factor to assisting in pitch down torque.

Many aircraft have their thrust line angled down a few degrees, which helps control pitch up tendency as the plane accelerates.

Choice of sound and proven design is important, as well as keeping CG within limits.

No, it is not possible that the nose will “refuse to go down” with “the rear end pointed straight down”.

If the aircraft is going down tail first, then there IS airflow over the wings.

It may be briefly in the wrong direction, but the center of gravity and placement of the wings will soon have it pointed in the correct direction.

With the nose pointed down again, the wings may still be stalled, but there will be airflow over the wings, and the stall will be recoverable with the correct control inputs.

If a conventionally laid out aircraft is flown into a tail slide, it's unlikely that it could maintain that attitude for long.

The tail has low mass relative to the rest of the aircraft and a substantial moment between the tail surfaces and aircraft center of mass.

As negative airspeed (falling down tail first) builds, aerodynamic forces on the tail will cause it to flip around.

Angular momentum will continue the rotation until there is enough opposing aerodynamic force to stop it.

While a deep stall may be unrecoverable, a tail slide should be recoverable, given a sturdy airframe, enough altitude and the correct control inputs properly timed.

Hypothetically:

Given an aircraft of conventional layout, if it was released at zero airspeed and level attitude, the greater surface area of the tail as well as the greater surface area of the wing aft of its center of gravity will create a force that will rotate it nose down.

What distinguishes this sort of scenario from a deep stall is that the condition is unstable and robustly forcing the airframe towards a normally-oriented airflow.

Question: So basically, a stall from a high AoA to the point that the entire plane just falls with the rear end pointing straight down?   Because if wind is no longer passing over the wings, then this includes the elevator, and the elevator can’t deflect the wind with no forward speed?

Is it possible to stall a plane so badly that the nose refuses to go down due to lack of airspeed?

Yes it's called a  Deep Stall , and is mostly a problem with T Tail aircraft, especially jets with Supercritical Airfoil wings (like the CRJ Regional Jet line).  Moving CG farther and farther back will eventually cause the plane to be directionally stable falling backwards.   Secondly, poor design of horizontal stabilizer, particularly, lacking sufficient "weathervaning" area, will cause an aircraft to be more susceptible to the unrecoverable "deep stall".

While some would argue that this kind of stalling is impossible or at least highly unlikely to happen, and when the aircraft is descending tail-first, there is airflow over the wings, it is mostly claimed that this kind of stalling is possible and is called a "deep stall" or a "tailside" and can manifest due to many factors, namely poor design of the stabilizer or moving the CG too far back. It is very hard to recover from this.

This kind of stalling is possible and is called a "deep stall" or a "tailside" and can manifest due to many factors, namely poor design of the stabilizer or moving the CG too far back. It is very hard to recover from this.

This kind of stalling is impossible or at least highly unlikely to happen, and when the aircraft is descending tail-first, there is airflow over the wings.


The problem is that in bypass engines, the fan blades are much longer than the turbine blades that drive them.

Both compressors and turbines should rotate as fast as possible, without shock waves occurring at the tip - so linear tip speed has an upper limit, meaning the compressor with longer blades must turn much slower than the turbine driving it.

This is what the geared turbofan does, reduces the rotational velocity relative to that of the turbine so that both can rotate at their optimum angular velocity.

The forces involved and the required reliability make it not an easy design task, as noted in this answer , Does it improve fuel efficiency?

It does, when both the fan and the compressor can rotate at their optimum speed, and when the gearbox does not add much friction.

The gearbox is located between the front fan and the rest of the engine.

It lets the front fan spin at a lower rate than the main shaft.

Image source: aerospaceamerica.aiaa.org

The advantage of this setup is that the front fan can have longer blades to cover a larger cross-section area, while the low-pressure compressor and turbine blades in the core can spin faster to improve fuel efficiency.

Image source: www.aviationpros.com

The purpose of the reduction gearbox is to improve engine efficiency.

Normally in a turbofan engine

the low speed turbine and fan are connected by a direct drive turbine shaft that requires the low turbine and fan to run at the same speed.

In a geared engine, the gearbox allows both the fan and turbine to run at their optimum speeds.

In this case, the turbine can run faster with fewer stages and airfoils, which increases efficiency.

The fan can run at a slower speed but at a larger diameter to push larger amounts of air at a slower velocity.

A simple formula for propulsive efficiency is: $$ N =

\frac{2}{1 +

V_e / V_o} $$ Where $V_e$ is the exhaust velocity of the engine and $V_o$

is the velocity of the aircraft or inlet of the engine.

As $V_e$ lowers to the point where it equals the speed of the aircraft,

efficiency N approaches 100%.

The larger slow moving fan in a geared engine allows large mass flow with low velocity which improves efficiency.

The low velocity also makes the fan quieter.

To increase the propulsive efficiency (total efficiency is the product of gas turbine thermodynamic and propulsive efficiency)

we need to accelerate more mass flow less fast: this requires larger fan diameters.

See e.g. this answer which describes how the bypass air provides thrust.

The formula: $$ F = \frac{\text{d}}{\text{d}t} p = m \frac{\text{d}}{\text{d}t}

v = m \cdot a $$ shows that increasing the mass flow $m$ for the same amount of thrust requires less acceleration $a$ .

This can potentially improve the fuel economy, but there is a limit, increasing frontal area will also cause the drag to increase.

As said in this answer , tip speed is a limiting factor, so we need to reduce the spool speed.

The problem with decreasing the spool speed is that the work generated in the low pressure turbine (which is coupled by a shaft to the fan) needs a large diameter and more stages to get enough power from the gas to power the fan (let's not get too technical in discussing blade loading).

A large low turbine diameter is not very effective for the bypass flow of the engine (how do you get the bypass air around it), therefore the spool speed of the low pressure turbine is increased to be able to use a smaller diameter.

This mismatch in spool speed requires a gearing solution.

Note that very large amounts of power are being transmitted through the gear box, even with very high efficiencies this requires a lot of heat to be dissipated.

Getting rid of the waste heat and the large loading has proven to be a very difficult design task.

The preceding explanations are good.

But - interesting add-on is the notion that the gearing of a turbine is hardly a new concept

- it's been around for decades in the form of turboprop engines.

The Allison T56 is an example of a geared Turboprop engine.

Simplistically, the difference between earlier turboprop designs and the more recent GTF design(s) - are the difference between a ducted fan and unducted propeller.

Question: I've read that the P&W PW1000G engine has a reduction gearbox. What is it and does it have any relation to the fan or compressor speed? Does it improve fuel efficiency?

What does a reduction gearbox do in a turbofan engine?

This is what the geared turbofan does, reduces the rotational velocity relative to that of the turbine so that both can rotate at their optimum angular velocity. The advantage of this setup is that the front fan can have longer blades to cover a larger cross-section area, while the low-pressure compressor and turbine blades in the core can spin faster to improve fuel efficiency.

It allows the front fan and the main shaft to operate each at their optimum speed and angular velocity, thus being more efficient.


Image source Larger helicopters have landing wheels, and as we can see on the picture above, they are placed as far outward as practically possible in order to provide stability in the landing.

Touch down one wheel on an sideways inclined slope, lower the collective, and the helicopter will align itself onto the slope with: The location of the Centre of Gravity (CoG) always in between the wheels.

The higher the CoG, the wider the landing gear impact points must be.

The weight being supported on clearly defined and structurally reinforced points.

Even if the bottom of the helicopter is perfectly flat, the landing ground may not be, and to support all of the weight at any random point at the bottom requires a lot of relatively useless weight for the re-inforcement.

The behaviour after first wheel touchdown being clearly defined.

The wheel is a point of impact upon the landing plane, mathematically much more defined than a plane of impact upon a landing plane if the latter is curved.

All the above is for wheels, which allow the helicopter to taxi on-ground.

Skids perform all of the above functions apart from the on-ground taxiing, and are cheaper and lighter than retractable landing wheels.

Of course, the other downside is that they have more drag.

One would not want to land this helicopter without the skids!

Physically they likely could, but helicopters (and all aircraft for that matter) tend to have stuff mounted to the bottom like antennas, probes, cameras etc.

so adding some kind of landing gear or skid helps to provide clearance for all that.

This question covers a bit about whats mounted where.

The belly of a helicopter also tends to not be perfectly flat (depending on the model)

so belly landing can lead to some roll which may allow the rotors to scrape the ground.

Skids are especially beneficial when the helicopter is supposed to land on rough ground, e.g. grass.

They move the body and the rotors farther away from the ground, thus giving both more clearance.

Compared to extending the body to the ground to achive the same effect, skids add less weight and significantly less air resistance.

Compared to wheels they are better suited for rough ground, as they have a larger contact area and thus tend to sink less into the ground.

Wheels on the other hand have the advantage when the helicopter usually lands on concrete or other solid ground.

Here they allow taxiing.

That's why you tend to see skids on smaller helicopters which tend to land on grass or other uneven terrain, while larger helicopters, which tend to land on more solid ground, tend to have wheels.

Also, skids are simpler than wheels, which also suits smaller, cheaper helicopters better.

Skids, as opposed to wheels, allows the pilot to get some sense of balancing tail rotor counter torque before lift off.

Skids would provide more drag until the pilot "got it".

Same thing moving forward, backwards, or side to side.

The skid friction limits movement (or damps it if you will), rather than creating a nightmare of correct/overcorrect in 2 dimensions. Skids also add an important amount of rotor clearance, and offer simplicity, reliability, and light weight.

An additional benefit of longer skids is some energy absorption upon a vertical crash.

The skids are generally designed to bend outwards and up during impact.

This can be seen occurring on many helicopter crash videos.

The design of impact absorbing skids is covered extensively here .

As pointed out above, not all helicopters use skid style landing gear.

Some have either a fixed or retractable wheeled undercarriage.

These offer excellent mobility on paved or short cut grass airfields, surface taxiing, rolling takeoffs or landings or for movement aboard ship.

Surface taxi also consumes a little less fuel than hover taxi or takeoff from an IGE hover, but are more complicated, heavier, and expensive than skid type landing gear.

Smaller, utility helicopters usually use a skid type landing gear For several reasons.

Lightweight.

Inexpensive.

Flexible and can absorb impact of a hard landing or crumple to absorb energy.

Easy to replace if damaged.

Provides a large, stable support for pinnacle or slope landings.

More even distribution of aircraft load for landings in soft or waterlogged fields.

Lends itself better to being fitted with fixed or emergency inflatable floats for over water operations.

Can provide support for personnel flying outside the airframe.

The downsides to skids are

Do not allow the helicopter to be easily moved or towed on the ground; must be fitted with towing dollies or placed on towing trailer.

Surface movement limited to hover or air taxi.

Are fixed and cannot be retracted and faired, thus adding more drag in flight.

Easier to snag on obstacles and wires during surface operations.

More susceptible to side loads during takeoff and landing, which can cause dynamic rollovers.

Great skill must be used during rolling takeoffs, shallow descent landings or autorotation to keep the aircraft moving in a straight line down the runway to prevent side loads.

The aircraft’s fuselage is shaped primarily to provide the best aerodynamic fairing for the cabin, engine and transmission and aircraft systems; it is not necessarily the most stable platform and does not provide any shock absorption in case of a hard landing or an autorotation landing.

Landing gear is designed to solve that problem.

The siding of the skids is based on a lot of things from the ability to provide solid, stable support on uneven terrain to prevent the onset of potentially deadly ground resonance during a harder than normal landing to offering good ground clearance.

Question: Why can't they just land on the helicopter's floor? If it's for stability, they could still use skids which are shorter than what is commonly used.

Why do helicopters have skids?

Helicopters have skids because they absorb the impact on landing. They also provide more stable landing on difficult terrain. Moreover, as helicopters often have equipment fitted to the outside, e.g. cameras, the skids can be used for this. A further advantage is they can be fitted with floats for activities over water. However, not all helicopters use skid-style landing gear.

There are many advantages to skids: they are ideal for landing on rough surfaces, they are light, inexpensive, flexible and can absorb impact, easily replaceable, can be fitted to land on water, provide easier landing and more room for equipment appended to the underside of the helicopter and support for personnel. A landing on their belly is often problematic because the belly is not perfectly flat and can often lead to some roll and possibly endanger the helicopter's equipment. Even if it is perfectly flat, the surface on which it has to land will most probably not be. That said, there are in fact helicopters that do not use skids to land.

The higher the CoG, the wider the landing gear impact points must be.

There are helicopters that do not use skids to land.


There are a number of human-powered aircraft (list here ).

For the Gossamer Albatross , we have

In still air, the required power was on the order of 300 W (0.40 hp), though even mild turbulence made this figure rise rapidly.

As far as top speed: Allen completed the 22.2 mi (35.7 km) crossing in 2 hours and 49 minutes, achieving a top speed of 18 mph (29 km/h) and an average altitude of 5 ft (1.5 m)

Sailplanes employ zero horsepower by conventional reckoning, though an alternative definition can be proposed using the component of the aircraft's weight that acts parallel to the airspeed vector as the thrust-like force.

Anyway, the world records for sailplane flight appear to include 2191 km as greatest free distance along a course involving three or fewer turnpoints, and 22657 m as maximum absolute altitude.

Source:

fai.org/page/igc-records OK

, I thought the original question said "aircraft"; I now see "airplane".

Does "airplane" always exclude "glider"?

Originally, the "plane" in "airplane" referred to the "planing" action of the wing surface, and had nothing to do with the presence or absence of a motor, though there may be no specific examples of the word historically being used in reference to gliders.

Didn't see the "no gliders!

when I created this answer-- sorry!

Some self-launching powered hang gliders and powered paragliders/ paramotors intended for soaring flight must be close contenders for the answer to your question, as some of them have rather weak engines and are barely able to climb in the absence of an updraft despite overall light weight.

Even though at 4 x 13kW its max rated power (70hp) is higher than the other answers, Solar Impulse flew almost 5 thousand miles non-stop during close to 5 days.

It did not typically fly anywhere close to its max rated power in order to conserve energy that it would have to spend during the night.

Wikipedia lists the specs as: Maximum speed:

140 km/h (87 mph) Cruise speed: 90 km/h (56 mph) 60 km/h (37 mph) at night to save power Service ceiling:

8,500 m (27,900 ft) with a maximum altitude of 12,000 metres (39,000 ft)

This is of course much higher than the human-powered Gossamer Albatross in Eugene Styer's answer , but the Wright Flyer , "the first powered, heavier-than-air machine to achieve controlled, sustained flight with a pilot aboard", used a 12 horsepower gasoline engine which is a bit under 9 kW.

The longest of its 4 flights was 260 m, and it was apparently so light that "a heavy gust picked up the Flyer and tumbled it end over end, damaging it beyond any hope of quick repair".

Later versions used more powerful engines.

The lightest remote control airplane I could find is 0.225g (0.01oz).

Wing span 71 mm.

Length 70 mm.

(about 3") I estimate it used a few hundredths of a watt. https://www.rcgroups.com/forums/showpost.php?p=11048403&postcount=1

That was back in 2008 though, so they've probably done better since then.

The twin engined Columbian Cri cri might be a contender: each of the single cylinder piston engines were about 15hp.

Cruising speed is 190km/h.

Wikipedia article

Question: What manned airplanes have achieved flight with the least powerful engines (no gliders!), and what was their top speed? Im sure I've heard of an airplane with an 8hp engine capable of exceeding 120 MPH airspeed

What are the least powerful airplanes that ever flew?

The twin engined Columbian Cri cri might be a contender for the flight with the least power ever: each of the single cylinder piston engines were about 15hp.

The main contenders that fulfill the criteria are: the twin engined Columbian Cri cri, a sailplane or the Solar Impulse.


First I have to admit that I have no idea what FAA regulations said about passengers taking part in controlling an airplane in 1989, but I guess it was at least frowned upon, even if the passenger happened to be a pilot.

The United Airlines flight 232 made a stunningly successful "landing" at Sioux City airport, much due to the fact that they took an extra crew member from the cabin to control the throttles of their severely disabled aircraft.

Unfortunately 112 people lost their lives as the plane cartwheeled after a very rough touchdown, and one might ask what is so successful about that...

well: 184 people survived a situation that was in subsequent simulations deemed to be impossible to manage.

The throttle operator was a UA training check airman Dennis Edward Fitch, riding as a passenger on this ill-fated flight.

It has been stated in many sources again and again, that without his presence in the cockpit, the outcome would have been much worse, even the worst possible.

It just so happened, that Fitch had been practicing a similar scenario in a simulator after a fatal crash of Japan Airlines flight 123 in 1985.

The reason of that crash was total loss of hydraulics, Fitch wanted to find out if an airliner could be controlled with throttles only.

Luckily, it was somewhat possible.

The rules say to do whatever necessary to ensure safety of flight.

91.3 Responsibility and authority of the pilot in command.

(a)

The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft.

(b)

In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency.

(c)

Each pilot in command who deviates from a rule under paragraph (b) of this section shall, upon the request of the Administrator, send a written report of that deviation to the Administrator.

As pointed out above pilots may deviate from any regulation in the event of an emergency per §91.3(b).

One of the more common events is a civilian aircraft making an emergency diversion and landing at a nearby military airbase, such as this 777 flight which diverted to Erickson AB, Shemaya, AK .

The OP brings up the case of Cactus 1549.

But what Sully and Stiles did in powering up the APU first wasn’t a violation of the rules per se, though I’m sure there are plenty of odious airline sim

check pilots that cut themselves on their overstarched undershirts who would disagree with this.

This even brings up an interesting discussion I once had with a flight instructor examiner I knew who had been a Air Safety adviser to Korean Airlines.

He told me he once conducted a systems discussion with a group of KAL 747 pilots in regards to understanding their systems in an emergency.

The KAL pilot corps at the time apparently handled their pilots in a very regimented and militaristic fashion.

When the chief pilot walked in, they all jumped to their feet and stood at attention, etc.

So this examiner guy walks up to the front of the group of the group and asks them: “Ok, so what is the emergency procedure for an engine fire on a 747-400?”

The entire group barks out the QRH entry for this contingency at the top of their lungs perfectly and in unison.

“Okay.......so what two things do you do in the event of an engine fire if you only have time to do two things?”

Dead silence.

The entire room stares blankly back at him like a second grader at a spelling bee asked to spell ‘photosynthesis’.

OEM approved procedures, standardized general operating practices and legal regulations for aviation are great guideline for safe and reliable operations but they can’t always cover every contingency perfectly.

A fundamental knowledge of your aircraft and it’s systems from a correlation level can come in real handy sometimes if you encounter something serious that’s not been documented.

It’s

something test pilots know all too well, as it can allow them to make very judicious choices on flight test plans and handle unforeseen problems once in the air.

In 2017 an MD-83 aborted takeoff above V1.

The pilot was widely criticized for that, which was against a lot of rules and conventional wisdom.

The NTSB report determined that aborting above V1 was the most correct thing to do in this case. https://www.planeandpilotmag.com/article/ntsb-report-how-this-pilot-saved-116-lives/#.XkzGlopOmhA

There have been cases with incorrectly wired controls , with the aircraft doing the opposite action than such a wrongly wired control commands.

Then the narrow rules about how to use the control to achieve intended action must be completely reversed, moving the stick in the opposite direction.

Doing so does not break the wider rules that cover such malfunctions.

But I imagine how difficult is to realize them happening at the first place.

This is the main reason I would never like to have just a robot in the cockpit.

I will note that in maritime law there is the General Prudential Rule which states that avoiding a collision takes precedence over strict adherence to other rules and regulations.

I would have to believe that there are similar provisions in aviation rules.

Question: I wonder if there is an incident that pilots saved the plane or minimized the damage by bending or breaking the rules like Sully? (As it's known  Sullenberger  started the APU at first which was the 15th thing in QRH.)  Thanks in advance.

Has any accident been prevented by bending or breaking the rules?

The rules say safety is paramount and pilots may deviate from any regulation in the event of an emergency per §91.3(b).  There have been a number of crashes averted by bending the rules. They include the  United Airlines flight 232  made a stunningly successful "landing" at Sioux City airport, much due to the fact that they took an extra crew member from the cabin to control the throttles of their severely disabled aircraft.  One of the more common events is a civilian aircraft making an emergency diversion and landing at a nearby military airbase.

There have been such instances, like the landing of United Airlines flight 232 where they took an extra crew member to help control the aircraft, civilian airctaft landing urgently at military bases, a case of an MD-83 aborting takeoff above V1, or cases of incorrectly wired controls that need deviation from standard procedure to be operated. However, the main rule, above all else, is that the pilot must take whatever action deemed most efficient for the safety of the flight.

The main rule, above all else, is that the pilot must take whatever action deemed most efficient for the safety of the flight.


No, you would need to arrange for customs as you are crossing an international border.

Yes, it is possible to land an airplane in the US at a private airport when you have taken off from a foreign airport.

No, you may not do it legally.

Doing this is a federal crime.

Since you are smuggling something, you may not care about the legality.

When you are eventually caught, you will go to prison.

Your assets will be confiscated by and forfeited to the government.

And once you are released from prison, you will be deported and blacklisted from entering the US ever again.

Your gold will not be returned to you.

It is not worth the risk.

Especially when the gold is worthless unless you can convert it to money.

You can’t do that legally either (more prison time).

Even money gotten through illegal means is forfeited to the government.

No matter from where you takeoff, nor in what country your aircraft is registered, if you cross the US Air Defense Identification Zone, you have to land at an Airport of Entry before proceeding elsewhere.

You have to declare any goods or monetary instruments (even gold)

you are transporting to Customs and Border Protection located at the AOE.

There are trade laws, aviation laws, customs laws, banking laws, tax laws, Anti-terrorist laws, etc.

that you will be violating if you do not.

In general*, any time people or cargo enter another country, they must do so at a designated Port of Entry, i.e. where customs and immigration officers are stationed.

This is true regardless of whether traveling by land, sea or air.

Trying to enter other than at a PoE is usually a serious crime , and in the case of flying without a proper flight plan, may even get you shot down .

In the US specifically, you can request (for a fee) that these officers meet your flight at an airport other than a designated PoE, which is a really convenient perk for GA pilots.

As far as I know, they will only agree to do this at public airports, and if you ask about a private airport such as your friend's farm, they'll tell you to land at a public airport first to legally enter the country and then continue to the private one as a domestic flight.

(* Open border agreements like Schengen are an obvious exception.)

Think about how your question is fundamentally different from this one: If you have friend in the USA that owns a lot of land that is suitable for landing a plane, and you own a private jet with 2 pilots in Colombia , can you takeoff in private property without notifying anybody on what you have on the plane and where you are going or anything like that and fly to USA and land on the property of your friend?

Is that legal to do?

But would anybody notice that I'm transferring cocaine if the cocaine is hidden

and I put the cocaine there long before the actual travel.

And would I need to arrange customs to come to me?

And how would I do that.

This is just me wondering if this is actually possible.

I'll bet you can answer this question all by yourself without even consulting additional sources.

If not, you can probably put on your Customs and Border Patrol hat and ask yourself: "What would I think of a covert flight of this nature crossing into my airspace?

It's probably a totally cool, totally legal flight with no contraband on board.

I'm gonna go ahead and do nothing."

No, your plan could never succeed.

You could not file a legal flight plan since your plan has no provision for landing at an appropriate port of entry for customs and immigration clearance.

If you attempt to make the flight without filing a flight plan, you would necessarily need to transit the North American ADIZ (Air Defense Identification Zone) .

The map below does not show the Alaska zone, but rest assured it also exists - there is no way to cross into the north american land mass without being detected.

Any aircraft flying in these zones without authorization may be identified as a threat and treated as an enemy aircraft, potentially leading to interception by fighter aircraft.

With no defensible justification for your presence in that airspace you would be treated as a hostile aircraft and dealt with as such. Image Credit.

I'm certain there will be problems with this, because this is very much the way smugglers move goods across a border without letting customs authorities inspect it.

If you cross from international airspace to American, without a flight plan, at the very least you'll be directed to land at a recognized airport for customs, and if you don't respond to attempts at contact, it's possible warplanes might be dispatched to intercept you

-- this could even go as far as a shoot-down, in the worst case.

Even if you "aren't smuggling," if you have anything of value on board, this kind of flight is smuggling.

It will also run afoul of immigration laws, if anyone on board isn't an American citizen (and will be seen as suspicious in that regard even they are).

Question: If you have a friend in the USA who owns a lot of land that is suitable for landing a plane, and you own a private jet with 2 pilots in Norway, can you take off in private property without notifying anybody on what you have on the plane and where you are going or anything like that and fly to the USA and land on the property of your friend? Is that legal to do?

Can a private jet take off without notifying anybody and land on private land in another country?

The majority of people believe that it is illegal to pilot a private plane across borders and land on private land rather than a recognised port of entry, for customs and immigration reasons. It is however possible as this is how smugglers move goods around.

As far as the question of if it is possible to land the aircraft at a private airport in the US in the manner described is concerned, it is, though it would be entirely illegal. All incoming international flights are required to have a flight plan and pass customs. Failing to do so is a federal crime and would lead to many legal woes. Doing it would also violate immigration laws if the passengers on board are not American citizens.

Doing it would violate immigration laws if the passengers on board are not American citizens.

No, this is not possible. All incoming international flights are required to have a flight plan and pass customs. Failing to do so is a federal crime and would lead to many legal woes.

It is possible to land the aircraft at a private airport in the US in the manner described, though it would be entirely illegal.


Your best bet would be an airplane/drone that is built from carbon composite and graphlite rod (pull-truded carbon rod with incredible strength - widely used in sailplane spars) powered by a couple of aviation diesels like the Austro Engine E4 .

The Specific Fuel Consumption of the E4 is .336

lbs/hp/hr.

Except for similar competing diesels, nothing in any traditional aircraft engine configuration comes close except the old tubro-compound mechanical-monstrosity radials like the R3350 that could get into the high 3s (normal gas piston engines are around .45 lb/hp/hr and turboprops well above that, around .5-.6 lbs/hp/hr).

The E4 is 168 Hp so two would give you 336 HP for take off, and the engine burns 5 US Gal per side at 60% cruise, or 30 lbs per side, so to go 2000 nm, if you can get the thing to cruise at 150kt, you need 130 US Gal capacity plus a VFR reserve, say 140 gal total, or 840 lbs of fuel.

So design an airframe that can haul, say, a thousand pounds of payload with those two engines and 840 lbs of kerosene, and is clean enough to go 150kt, and there you have it.

It's perfectly possible to build piston-engined planes with ranges of 2000 miles or more, for instance many WWII planes like the B-17 and B-29, pre-jet airliners like the Lockheed Constellation, or the Rutan Voyager.

The reason there are few, if any, in service today is that there is no real market.

Jets have taken the long-range commercial market, and pilots of smaller planes generally don't want to go that far without stopping for bathroom breaks.

If you are looking to design an unpiloted plane, the problem becomes even easier.

You should be able to use modern, non-certified engines derived from the automotive market, can fly at efficient speeds, and don't have to worry about breaks.

This is perhaps not going to be a very good answer to the specific question, but the mission you describe would constitute some out-of-the-box thinking.

As John K already suggested, a very light construction, perhaps in the spirit of Rutan Voyager suggested by Jamesqf would be a good starting point.

Large wingspan to get efficient wings would give the chance to use less powerfull and/or exotic engines.

John K's example of Austros is a good one.

In my mind what you should design is a motorglider on steroids.

Relatively large cargo would otherwise require a lot of thrust, but you could compensate with wingspan and 2 or even three lifting surfaces.

Leaving the pilot out would save at least 400 lbs of weight (pilot, seat, controls, gauges and such), plus you would not need any pressurising, so you could fly ballistic profile flights: high power ascents (but not that steep

as exess thrust is not great with full cargo), and the gliding the rest of the way.

You could even feather the props and shut down the engine -> no cruise consumption (piston engines typically are not very efficient when operating in partial load = cruise).

I don't think speed is of essence here, as even a cruise (or in the case I'm proposing, glide) speed of say, 100 kts would be, knowing the infrastructure there , at least ten times faster.

I see one real problem though: landing at destination, automatic or remotely controlled?

If rc, how?

Satellite would be the only aplicable solution, but might prove troublesome with videostream bandwidth, lag etc.

If automatic, oh man the effort of programming relating to all that needs to be taken into account.

So: is dropping the cargo by parachute out of the question?

The main distance limitation for a plane is weight: every extra pound of fuel means one less pound of payload.

Planes can be equipped with "ferry tanks" that increase endurance for long open water legs, but then they're bumping up against (or even over) maximum gross weight with just the pilot (no passengers or cargo).

Take the pilot out and you can add more fuel to go even further.

Unless your goal is moving the plane itself, though, having no weight left for payload doesn't really allow anything useful to be accomplished.

Note that aircraft range is often specified for something like 75% power at cruise.

Since drag is proportional to speed squared, flying slower would use a lot less fuel and thus extend your range, which may be fine for a drone that lacks the human need to stop every few hours.

2000 miles with a piston engine has been done more recently - check Wikipedia's entry for the AAI Aerosonde, which crossed the Atlantic (2031 miles) burning only 1.5 US gallons of fuel.

It includes a reference to the later "Spirit of Butts' Farm" which did that as well with a total gross weight of 11 pounds / 5 kilograms.

Autopilots are far more capable and small than they were then and often include autoland capability.

What you want to do can be done.

Question: Ok so Im exploring ways to bring cargo and medical supplies to various rural cities in say Africa without relying on ground infrastructure. Just short and cheap runways spread around the continent. It seems any type of VTOL plane wouldn't have the range. Electric is also out. It also seems like piston planes don't have the range, while turbojets are millions of dollars. What about used turbojets? Whats stopping piston engines from flying longer?

Can you fly 2000 miles on an engine that costs less than $500k? If so, what type of engine?

It's perfectly possible to build piston-engined planes with ranges of 2000 miles or more, for instance many WWII planes like the B-17 and B-29, pre-jet airliners like the Lockheed Constellation, or the Rutan Voyager.  It is also possible to use a couple of aviation diesels like the  Austro Engine E4.  If you are looking to design an unpiloted plane, the problem becomes even easier.  Moreover, you should be able to use modern, non-certified engines derived from the automotive market, can fly at efficient speeds, and don't have to worry about breaks.

A good solution would be to use carbon composites and graphite, paired with aviation diesels, to design a new airplane or drone. You could also consider designing a light piston-engined construction with large wingspan. The Rutan Voyager or a powerful motorglide might be a good source of inspiration to this end. Finally, autopilots could be a good idea, as they are small and efficient, and offer additional advantages like autoland or the possibility to use non-certified engines.

Your best bet would be an airplane/drone that is built from carbon composite and graphite rod (pull-truded carbon rod with incredible strength - widely used in sailplane spars) powered by a couple of aviation diesels like the Austro Engine E4 .

Consider designing a light piston-engined construction with large wingspan. In this context, an autopilot might be easier to build, as you could use non-certified engines. The Rutan Voyager or a powerful motorglide might be a good source of inspiration to this end.

Autopilots could be a good idea, as they are small and efficient, and offer additional advantages like autoland or the possibility to use non-certified engines.


All aircraft are subject to performance changes due to fuel burn, and since weight, lift, thrust and drag are all tied together for every aircraft in the same way the changes scale nicely.

Let's look at some extremes: One of the most interesting examples of this was the Concorde.

Since the Concorde flew ~20K above every one else in the sky in those days it didn't have the same altitude holding restrictions that regular airliners (or any IFR airplane) has.

The Concorde was give a block altitude basically to do what it wanted up around 50,000 feet (ca.

15 km).

Since it burned quite a bit of fuel at Mach 2.1 and gradually became lighter during the flight the pilots let the plane slowly drift up to gain efficiency as well as gliding distance if needed.

The Concorde also used its many fuel tanks to trim the aircraft as well as cool the nose cone.

Fuel burn was closely monitored and constantly pumped around to ensure the aircraft remained in trim.

Even the dinky Piper Archer

I fly is affected by partial tanks.

If I fly the tanks from full to VFR legal reserves, the CG moves forward a full inch.

Granted this does not seem like a lot you will need to trim to compensate for this throughout the flight.

You will also be landing a full 240 LBS lighter which is about 10% of the total weight from takeoff.

If you come in hot and high you can get yourself into trouble.

Yes you can feel it, generally pilots are not going to do “faster” maneuvers but the maximum G load may change ( see your aircraft's POH for more info ).

Any smart pilot should practice flying their aircraft at various fuel loads to understand the differences it makes in performance and handling.

Some aircraft with things like tip tanks or auxiliary tanks even have fuel burn limitations that define where the fuel is to be burned from and in what order, again going from something as small as a Bonanza all the way up to the Concorde as discussed above.

Just how much can the handling change?

Assuming you did your due diligence in pre-flight and calculated your W&B on both ends of the flight accounting for fuel burn to ensure you are within your CG limits

the flight should occur with in the limits of the aircraft's POH and generally speaking within operable limits of the airframe.

FAA certified aircraft have control force limits so even at the extents of the CG range

you should be able to trim the aircraft to handle “normally”.

You will likely notice pitch differences (at either extreme) as well as various performance number differences.

Modern gliders are an interesting data point regarding this.

A competition glider carries water in its wing tanks to increase weight.

This betters performance at high speed, which is essential for competition when conditions provide strong lift.

The pilot can release the water at will, and the tanks can be emptied in a few minutes.

This happens in competition every day, either when you are arriving (to land without the extra weight) or sometimes mid-flight when conditions are worse than expected.

So, taking as an example a Ventus 3: This glider, with pilot included, weighs around 380kg.

It can carry up to 212 litres of water in its wings, for a maximum gross weight of 600kg (it also carries a few litres in the tail for cg purposes).

In summary, the pilot can change the weight of the glider from 600kg to 380 kg in some 4 minutes (meaning a 38% change in weight!).

This makes the change very noticeable.

When empty, the glider is more "feisty", both in that it reacts more to turbulence, and in that the commands (the ailerons, especially) are way more effective.

Aircraft performance does change with weight.

Not only does takeoff weight and balance need to be considered, zero-fuel weight and balance does as well.

Many key performance metrics depend on this, like takeoff and landing speeds and distances.

Climb performance and range are also affected.

Inflight, Va (maneuvering speed) is very dependent on weight.

The speed at which you can fly while putting extreme loads on the airframe from abrupt maneuvers or turbulence actually decreases as weight decreases.

Something else that changes with a change in CG and/or weight is your stall speed.

There is a good article from AOPA here: https://www.aopa.org/news-and-media/all-news/2020/march/flight-training-magazine/aerodynamics-stall-speed

Alone in an A36 Bonanza from central Florida to North Central Indiana, I flew on one load of fuel by decreasing the throttle gradually as I burned fuel to maintain a constant airspeed.

The aircraft wanted to speed up as it lost weight.

So, yes the aircraft will fly differently as the fuel is used.

Question: Modern aircraft are capable of carrying a lot of fuel to achieve extra-long range; we're at a point where nearly every pair of destinations can be reached non-stop. Carrying so much fuel imposes limits on take-off and landing weight, so the proportion of fuel to airplane weight is not negligible.  I'm wondering how the handling characteristics of airplanes change as the fuel is used up. Do the pilots feel that the airplane is lighter towards the end of the flight? Can they do faster maneuvers with nearly empty fuel tanks?

How do handling characteristics depend on flying with a full vs. an empty tank?

Aircraft performance does change with weight. Pitch differences (at either extreme) are noticeable as well as various performance number differences. All aircraft are subject to performance changes due to fuel burn,  and since weight, lift, thrust and drag are all tied together for every aircraft  in the same way the changes scale nicely. Many key performance metrics depend on this, like takeoff and landing speeds and distances. Moreover, climb performance and range are also affected.

As a general rule, aircraft performance can be affected by weight, including fuel weight. Examples illustrate that, as aircrafts consume fuel, they become lighter, gain efficiency and display pitch differences in various values. Gliders, on the other hand, are designed to carry water for extra weight. This design improves performance at certain speeds, as it makes a stronger lift possible, facilitates aileron operation and stabilizes the glider body. Areas affected by weight change include takeoff and landing, climbing and in-flight. On the same note, it is worth noting that when manoeuvres add load to the airframe, turbulence tends to decrease along with weight, even though aircrafts generally increase their speed when losing weight.

It is worth noting that when manoeuvres add load to the airframe, turbulence tends to decrease along with weight, even though aircrafts generally increase their speed when losing weight.


As far as I know, there is no actual flying boat in use at an airline.

The flying boats that are still in commercial operation are typically used for fighting forest fires or maritime patrol.

This may change in the near future since there are currently at least two flying boats in development that might be used by airlines: Dornier Seastar CD2:

This is a newer model of the previous Seastar , which had its first flight earlier this year:

Dornier Seawings flew its new-generation Seastar amphibian for the first time on 28 March from its base in Oberpfaffenhofen, Germany. [...]

Dornier says the aircraft will be offered in various configurations including cargo, passenger , special missions and VIP transport.

( flightglobal.com , emphasis mine) AVIC

: This is new aircraft developed in China and one of the biggest flying boats ever.

It had its first flight in 2017 and according to Wikipedia is expected to be delivered by 2022, possibly also in a passenger variant: Further variants may be developed for maritime surveillance, resource detection, passenger and cargo transport.

If you are not just interested in pure flying boats, but also floatplanes , then there are many airlines world wide that operate these on regularly scheduled flights.

One of the biggest is Trans Maldivian Airways operating various variants of the DHC-6 Twin Otter.

They operate 55 seaplanes, which according to Wikipedia makes them the biggest seaplane airline: TMA currently operates the world's largest seaplane fleet.

They offer flights to over 80 destinations:

Trans Maldivian Airways currently offers transfer services to more than 80 Maldives resorts, flying over 1 million passengers per year to their holiday hideaways.

( transmaldivian.com )

This is their main terminal at Velena International Airport: (image source: Wikimedia )

Last time I was there (fifteen or so years ago)

there was a thriving commercial air passenger operation, including at least a couple scheduled flights (weekly, I believe, not daily), at the north end of Lake Washington (near Seattle), officially in either Bothell or Woodinville, Washington state (comments reminded me

it's Kenmore Air, in Kenmore, WA).

There were no flying boats in service there, but there were Beavers and Otters on floats.

Beyond that, there are a number of tiny (one or two aircraft)

airlines operating scheduled feeder service in Alaska and northern Canada that operate on floats, because lakes and rivers are much more common in the wilder parts of the sub-Arctic and Arctic than even grass or gravel airstrips.

As long as there's water to land on at both ends, such aircraft are good to go (and some have retractable gear, so they can land on concrete if necessary) -- and if you're starting from a village equidistant from Fairbanks and Nome, these are likely to be your only choices for local service.

The bulk of their revenue is likely from hunting and fishing charters, like any bush operation -- but many of them operate weekly or twice-weekly scheduled flights to a hub terminal.

There is at least one jet flying boat, the Beriev B-200 , in production.

The Wikipedia article gives it a capacity of 72 passengers.

I don't know how many (if any) are employed in an airliner role, though this variant has a "pressurised and air conditioned cabin allowing transportation of up to 72 passengers.

The passenger variant is the BE-210 shown here at beriev.com Most seem to be employed as water carriers in a firefighting role; it was designed to skim the surface and scoop up water at close to takeoff speed.

Four or five years ago or so, Pacific Coastal Airlines spun off its seaplane division as Wilderness Seaplanes , which flies scheduled service in a fleet of four Grumman Gooses in British Columbia.

Not "air carrier service", but Viking Air acquired from Bombardier the type certificates and continues to produce the CL-215, CL-215T, CL-415 and CL-415EAF as an aerial firefighter , an amphibious aircraft.

Again, not "air carrier service" but a true flying boat, Coulson Flying Tankers effectively grounded the last Martin Mars water-bomber in 2018.

They are fondly missed.

The following relates to "Float planes", rather than "flying boats or seaplanes" ...

Viking Air also hold the type certificate for the legendary De Havilland DHC-2 Beaver DHC-3 Otter and DHC-6 Twin Otter .

A refreshed, next-gen specification Twin Otter - series 400 is now back in Production.

From their website, With a fleet of 57 de Havilland Twin Otters, Trans Maldivian Airwaysoperates the largest seaplane operation in the world.

TMA is the airline referenced in @Bianfable 's answer.

NORDIC Seaplanes flies daily between the two largest Danish cities.

Question: Is there anywhere in the world that still offers scheduled air carrier service using flying boat / seaplane types of aircraft - something akin to a proper airliner? Or are they all limited to charters and shuttle-type flights on de Havilland Otters and the like?

Are there any remaining flying boat or seaplane airliners in operation?

It seems there are some arelines still operating seaplanes. Four or five years ago or so, Pacific Coastal Airlines spun off its seaplane division as Wilderness Seaplanes , which flies scheduled service in a fleet of four Grumman Gooses in British Columbia. In addition, NORDIC Seaplanes flies daily between the two largest Danish cities.

There are conflicting opinions on the subject. Two actual examples of airlines that might still offer regular seaplane service are Pacific Coastal Airlines and NORDIC Seaplanes. No flying boats seem to be currently used in air carrier service.