Risk factors. Factors that increase the risk of stuttering include: 1  Having relatives who stutter. 2  Stuttering tends to run in families. 3  Delayed childhood development. 4  Children who have developmental delays or other speech problems may be more likely to stutter. 5  Being male. 6  Males are much more likely to stutter than females are. 7  Stress.
The average speed for a four-seat helicopter is 130 to 145 miles per hour. Because smaller helicopters have smaller engines, the average speed for a two-seat is 90 to 105 mph. The fastest helicopter on Earth as of 2014, the X3 Eurocopter, can fly at 300 mph. Keep Learning.
Your jet aircraft usually stay around the same speeds though. Rotate speed is about 130-150 knots (150-170 mph). They then cruise anywhere from 250-400 knots (290-460 mph). Such a big possibility for the speeds because it all depends on the airplane.s fast as necessary to produce enough lift so the aircraft can safely fly. Some can take off with a forward speed of 40 miles per hour, others need speeds that are more than 150 miles per hour, & a few even more than that.