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Please include "Crashing Into Mountains" into the subject line. It's a bit clickbaity right now.

by mfringel 10y ago

tremon 10y ago
Indeed. Here I was thinking that ferrying passengers instead of other cargo was the largest cause of death...
- personlurking 10y ago
  I would think the best way to eliminate the largest cause of death (ferrying passengers) would be with a detachable cabin [1] but given that most accidents occur around take-off and landing, it wouldn't make much sense. http://www.independent.co.uk/life-style/gadgets-and-tech/news/why-a-detachable-cabin-probably-won-t-save-your-life-in-a-plane-crash-a6839156.html http://www.independent.co.uk/life-style/gadgets-and-tech/new...
  - throwanem 10y ago
    Yeah, I'd feel a lot safer aboard an aircraft that's designed to come apart.
  - rsync 10y ago
    This reminds me of my sometimes curiosity into why helicopters don't have a central parachute, presumably located in the center of the main rotor. Not a parachute for occupants, mind you - for the entire helicopter. Why isn't that workable ?
    - Retric 10y ago
      Auto rotation provides a built in parachute when the helicopter loses power. Mechanically losing blades is like a wing falling off an aircraft and basically never happens. There are a few edge cases dealing with loss of control that are rare. https://en.wikipedia.org/wiki/Autorotation https://en.wikipedia.org/wiki/Autorotation In combat helicopters ejection seats are just safer as 'helicopter on fire' is a real risk. Further, parachutes don't really work unless your well above the ground and in reasonably level flight in the first place where ejection seats can be safe near ground level or when the craft is violently flailing around at altitude. Finally, helicopters are one of those things that just barely works in the first place. Every pound you add makes them significantly more expensive over their lifetime.
      - Kluny 10y ago
        This might be a dumb question, but when an ejection seat is activated, what prevents the crew from being fired straight into the helicopter blades?
        Retric 10y ago
        They release the blades which fly off at high speeds.
    - thaeli 10y ago
      Helicopters get all their lift from the rotor. So, either there's a huge amount of air being blown around, making parachute deployment impossible, or the helicopter has no lift and is free falling, which doesn't give enough time to deploy a parachute at the low altitudes helicopters generally operate at. Small fixed wing general aviation aircraft are often equipped with ballistic parachute systems, however. It's just what you envisioned - a parachute with rocket-assisted deployment.
    - phreeza 10y ago
      In the case of engine failure the rotor acts as a kind of parachute (autorotation). If the rotor itselfgets damaged, the whole helicopter would probably start spinning wildly, making a parachute useless.
    - 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 ago
        I'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 ago
        The 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...
sctb 10y ago
We updated the title again from “Eliminating the largest cause of death in jetliner accidents”. We're open to better alternatives.

Please include "Crashing Into Mountains" into the subject line. It's a bit clickbaity right now.

tremon 10y ago

Indeed. Here I was thinking that ferrying passengers instead of other cargo was the largest cause of death...

personlurking 10y ago
I would think the best way to eliminate the largest cause of death (ferrying passengers) would be with a detachable cabin [1] but given that most accidents occur around take-off and landing, it wouldn't make much sense. http://www.independent.co.uk/life-style/gadgets-and-tech/news/why-a-detachable-cabin-probably-won-t-save-your-life-in-a-plane-crash-a6839156.html http://www.independent.co.uk/life-style/gadgets-and-tech/new...
- throwanem 10y ago
  Yeah, I'd feel a lot safer aboard an aircraft that's designed to come apart.
- rsync 10y ago
  This reminds me of my sometimes curiosity into why helicopters don't have a central parachute, presumably located in the center of the main rotor. Not a parachute for occupants, mind you - for the entire helicopter. Why isn't that workable ?
  - Retric 10y ago
    Auto rotation provides a built in parachute when the helicopter loses power. Mechanically losing blades is like a wing falling off an aircraft and basically never happens. There are a few edge cases dealing with loss of control that are rare. https://en.wikipedia.org/wiki/Autorotation https://en.wikipedia.org/wiki/Autorotation In combat helicopters ejection seats are just safer as 'helicopter on fire' is a real risk. Further, parachutes don't really work unless your well above the ground and in reasonably level flight in the first place where ejection seats can be safe near ground level or when the craft is violently flailing around at altitude. Finally, helicopters are one of those things that just barely works in the first place. Every pound you add makes them significantly more expensive over their lifetime.
    - Kluny 10y ago
      This might be a dumb question, but when an ejection seat is activated, what prevents the crew from being fired straight into the helicopter blades?
      - Retric 10y ago
        They release the blades which fly off at high speeds.
  - thaeli 10y ago
    Helicopters get all their lift from the rotor. So, either there's a huge amount of air being blown around, making parachute deployment impossible, or the helicopter has no lift and is free falling, which doesn't give enough time to deploy a parachute at the low altitudes helicopters generally operate at. Small fixed wing general aviation aircraft are often equipped with ballistic parachute systems, however. It's just what you envisioned - a parachute with rocket-assisted deployment.
  - phreeza 10y ago
    In the case of engine failure the rotor acts as a kind of parachute (autorotation). If the rotor itselfgets damaged, the whole helicopter would probably start spinning wildly, making a parachute useless.
  - 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 ago
      I'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 ago
        The 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...

sctb 10y ago

We updated the title again from “Eliminating the largest cause of death in jetliner accidents”. We're open to better alternatives.