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.
When you fly a fast helicopter, you need a fast chase plane. Eurocopter's X3 flies with an L39 Albatross during a test flight. HervÃ© Jammayrac knows fast. The Eurocopter test pilot set a new speed record for helicopters last week, achieving 255 knots (293 mph) in the Eurocopter X3 hybrid. That easily eclipsed the benchmark Kevin Bredenbeck set in the experimental (and conincidentally named) Sirkorksy X2 a little more than two years ago.