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RE: why the big deal?
By Mudhen6 on 6/8/2011 2:40:26 AM , Rating: 2
The rated output of the engine means nothing - e.g. 43 000lb of thrust is a useless figure. The actual output of a turbofan engine is highly dependent on external factors like speed and altitude.

For example, the Dash 229 engines in the F-15/16 are rated at 29 000lbs of thrust, but can probably produce anywhere from 3000lb of thrust to 40 000 of thrust at max output, depending on the amount of air its sucking in.

Lower speed = less airflow = less thrust from an air-breathing engine.

Higher altitude = less oxygen = also less thrust. Of course, air density has an inverse relationship to altitude, but a positive relationship with drag (i.e. flying at low altitudes/higher air densities generates more drag from the airframe). Drag also increases exponentially with increasing speed.

It is for these reasons (and more) that every single airframe/engine combination has a "sweetspot" in terms of the various aspects of performance. For example, the term "corner speed" is used to describe the "sweetspot" of the flight envelope that generates the highest sustained rate-of-turn within the smallest turn radius.

This is also the reason why fanboi arguments are bull***t. Sure, a MiG-29 may have the highest possible turn rate, but that kind of performance can only be attained at its sweetspot. IRL you can pretty much guarantee that (trained) enemy pilots will do their best to not fight in that particular part of the flight envelope, and instead try to suck the MiG-29 pilot into fighting in their sweetspot.

Back on topic, regarding the F-35 - the extra "100 lbs" of thrust is probably most welcome, in addition with shaving off 100lbs from the weight. Consider that Lockheed Martin started using thinner metal skins (IIRC) in order to make ends meet like a year or two ago.

Obviously, every little bit counts.

RE: why the big deal?


RE: why the big deal?
The 100lbs is probably a typo.





