Can anyone please help me out with a technical problem. If an airman jumped out of a plane without his parachute, I know that his terminal velocity would be around 120-125 mph but can anyone please tell me how far he would have fallen before he reached terminal velocity. The purpose of this is to help me assess the minimum height he could have fallen.
At lower altitude, approx. 10-12 seconds, falling some 450 m (1,500 ft) in that time. Around 15 secs from higher altitudes with variances based on atmospheric pressure, head down position, limbs pulled in, etc.
Wow, I am really impressed. I researched a jump of the US airman Conny Vogel. His para. did not or could not be opened. Sadly, he was killed with his legs up to the knees in the soggy groud of a potatoe field RIP Stefan.
Thank you Canuck, That is exactly what I wanted - a simple explanation that I can understand! (I am not a technical person) The necessary drop fits in well with the sort of height level that my target plane would be flying and even gives me a generous margin for error.
If you dropped something from a height, it would take 5.71 seconds to reach 125 MPH, not accounting for flapping arms. tucking, etc 125 MPH = 183ft/sec 32ft/Xsec^2 = 183ft/sec Xsec^2 = 5.71ft/sec X = 5.71 seconds Something falling for 5.71 seconds will travel for 522 feet before it reaches 125 MPH D= (32 x 5.71 ^2) / 5 D = 1043/5 D = 522 feet Lab conditions and not an airman, of course
Thanks Dave, That is another easy to understand formula! The conditions were that it was early hours of the morning (around 2 am) cold, wet and foggy with no significant wind. The airman had chest wounds/injuries and fell feet first but death occurred after impact - probably drowning in the deep bog. Major arm, leg and pelvis injuries were probably caused by the feet first impact and the body was found 6-9 feet down in the bog. It was found almost exactly one mile from the end of the runway and with the distances he fell (according to your figures) that looks like the pilot was trying to land i.e. he was in a low approach. All of this makes sense but unfortunately the plane and the rest of the crew were never found. So it looks like they are still in that bog - which is known to be well over 30feet deep in places.
In wartime reports,It was always said that the terminal velocity was 120 mph and looking at the graph indication of 50 metres/sec,it equates to 112 mph which reflects that understanding. There is the case of Nicholas Alkemade a Gunner of No 115 Squadron,out of Witchford on a raid to Berlin on 24 March 1944 who bailed out without a parachute and survived.Unable to locate his parachute he decided to leave his stricken aircraft without a parachute and survived after falling into deep snow.His velocity may have been reduced by falling through trees.The Germans refused to believe he could survive a jump from 18000 feet without a parachute.....thought initially he was spy,he was finally accepted as a POW. There was the specification of the parachute harness and clip tensile strength which would only take one parachutist.In an emergency,a crewman without a parachute would likely clip on his harness to another crew member's harness and conduct a tandem jump.Unfortunately when the parachute opened ,it applied a shock loading to the clip harness which failed, resulting in the second man falling to his death.I cannot see it recorded where a tandem jump in these emergency circumstances was successful during the war. If the parachute does not deploy,there is the danger of a "roman candle" being the outcome and a fall to death usually occurs.Parachute rigging being fouled up can also increase the terminal velocity and lead to injury and worse.Anne Marie Walters related that when she jumped on to her DZ at Gaberret in the Gers,her rigging was fouled and her rapid descent gave her reason for concern but through her training she was able to recover by kicking and kicking until the rigging became untangled and the parachute fully opened. As I recollect from limited parachute training....not actually jumping.A fundamental requirement of ensuring that the leg posture,ie,feet and knees together for safety on landing and a roll on to leg,thigh and backside.A normal parachute landing was said to be similar to jumping off a 12 foot wall but in our training the jump was off a 6 foot wall. Ground wind speed is crucial to prevent injuries and it thought that a wind speed of more than 15 knots increases the possibility of injuries being sustained on landing.
My brother took his first parachute jump in higher than average winds and has 3 pins in his right ankle to show for it. They scrubbed the remainder of the jumps that day after watching his descent.