Evel Knievel, The Ultimate American Daredevil
After thrilling audiences for many years jumping over cars, trucks and buses with Triumph, Laverda and Harley-Davidson motorcycles, Evel Knievel decided to take an extreme step; he set about planning a “jump” of Snake River Canyon in Idaho. Knievel engaged experts to help him build the rocket “bike,” including U.S. Navy engineer Robert Truax. After many delays for various reasons the jump took place on September 8, 1974.


Unlike Evel’s previous jumps on true motorcycles in which the landing was key, needed to be planned carefully, the Rocket Bike was to go airborne over the Canyon and when it got to the other side, a parachute would be deployed and would slowly lower Evel and the bike to the ground. In the jump, photo-documentation shows that the rocket bike technically cleared the canyon, was airborne over the far side, but the parachute deployed early interrupting Knievel’s trajectory. This and high winds caused the craft to stall in its arced flight and drift back, crashing onto the near canyon wall and landing near the river. Fast acting crew members extracted Knievel unscathed from the rocket.



To better understand how Knievel’s rocket was propelled, according to a listing for “steam rocket” posted on Wikipedia, water, while under pressure, is heated up to a high temperature (approx. 250-500 °C, 2.5 to 5 times the temperature of boiling water). As the hot water goes through the nozzle and the pressure reduces, the water flashes to steam pressing on the nozzle, and leaving at high speed. By the recoil, or opposite action, the rocket accelerates in the opposite direction to the steam. The nozzle of hot water rockets must be able to withstand high pressure, high temperatures and the particularly corrosive nature of hot water.


The jump rocket bike tours occasionally letting fans of America’s favorite dare devil take a look. Failure or no, the rocket bike sealed Knievels’ place in American culture. One of his jump bikes and other items are on display at the Smithsonian Institute in Washington, D.C. http://www.smithsonianlegacies.si.edu/objectdescription.cfm?ID=100. Or visit the National Motorcycle Museum in Anamosa, Iowa and take in a replica XR750 jump bike and great memorabilia including official pinball games, bicycles, action figures, posters, prints and more. Or check out collector Lathan McKay’s Facebook page and learn about his huge collection of Evel Knievel memorabilia which was on display at the National Motorcycle Museum June 8 & 9 during Vintage Rally 2013. https://www.facebook.com/lathan.mckay.7
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