3 ms·
Probably because Autorotation[0] works better than parachutes. Let it fall, and let the wind keep the rotors spinning, checking the fall speed just a bit to kee
by ufmace 10y ago
Probably because Autorotation[0] works better than parachutes. Let it fall, and let the wind keep the rotors spinning, checking the fall speed just a bit to keep the rotor speed under control. Save up enough energy in the rotors to slow to a soft landing just before you hit the ground. You also keep a pretty good amount of directional control, can turn and go forward and backward a moderate amount as needed.
A parachute big enough to land the whole helicopter would be huge even when folded and stowed and pretty heavy. I don't think it's at all practical to store it in the main rotor. It would have to be on the body, but the rotors would be in the way of a deployment, so you'd need a way to detach them safely that doesn't also make them weaker and more failure-prone. The helicopter would also have to remain falling in a stable way in order to deploy a parachute, but the rotors that are designed to keep the helicopter under control are in the way of the deployment. Yeah, let's just stick to autorotation for failure recovery, all we need is one little freewheeling mechanism on the rotor drive shaft, and we can keep using all of the same hardware and controls designed to keep the helicopter in stable flight, instead of doing without and hoping for the best or adding the weight and aerodynamic complexity of backup systems.
[0]https://www.wikiwand.com/en/Autorotation https://www.wikiwand.com/en/Autorotation
- downandout 10y agoI've never understood why both planes and helicopters don't have a small rocket that could be used to slow them down and bring them in for a soft landing just before impact. So a plane loses its tail and is falling for 40,000 ft....at 1,000 feet or whatever the rocket fires forward to stop forward progress of the plane, and then at a few hundred feet it fires vertically toward the ground to provide the lift needed for a soft landing. If an emergency happened during takeoff, the rocket could quickly slow the plane and fire it straight up into the air and out of danger in most circumstances, then let it fall and slow it down just before it reaches the ground. It wouldn't take much fuel for a few seconds of burn. It's not the fall that kills people; it's the landing.
- outworlder 10y agoThe tongue-in-cheek answer is that they are not designed by SpaceX. For large passenger airliners, how would that work? Are we supposed to strap LIQUID rockets to them? Precisely balanced around the center of mass? What if one of them fails? What if one of them is ignited when it should not? Who designs those things? How to guarantee structural integrity? Are the attachment points going to be reinforced? What would the FAA say? I could go on and on. Mind you, there have been planes designed with rocket-assisted take-off in mind. You won't find any designed for landings outside Kerbal Space Program. They'd need to be liquid fueled because they'd need to be throttled to fulfill all these functions. I am not even asking where the oxygen (or whatever oxidizer) would be stored...
- downandout 10y agoI didn't say it would be easy....but surely something could be done other than "let's hope nothing goes wrong...".