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Wanttaja

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Nope. Helicopters can autorotate. Quadcopters can't.

Not when they sling a blade...
Crewed quadcopters are going to require ballistic chutes. Because of the envelope issues with helicopter autorotation, a quadcopter with a BRS is probably going to be safer. Certainly less skill required for a successful outcome.

Ron Wanttaja
 

D Hillberg

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If you think governors are a bad idea, I can hardly wait to hear your opinion of presidents...
Governors make for lazy pilots - When he Army phased out he TH 55 and other piston trainers for the Bell TH57 and those happy pilots wen to fly hose lesser non governed helicopters hey all had problems with power management and went on to glorious careers of balling up Enstroms, Bell 47s Hillers and S 58s [1820 powered]
Plenty of topping out and over/under speeds too. As for presidents you're stuck with a Potato.

Those UH 60s make bad habbits when those guys step down to those lowly Rotorways...
 

dave wolfe

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Crewed quadcopters are going to require ballistic chutes. Because of the envelope issues with helicopter autorotation, a quadcopter with a BRS is probably going to be safer. Certainly less skill required for a successful outcome.

Ron Wanttaja

Quads are going to have envelope issues as well, between ground level and whatever height the chute needs for a safe deployment.

I havent seen any crewed multicopter concept that addresses this.
 

addaon

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Every certification-targeted eVTOL I've seen (as opposed to Part 103 concepts) has been able to handle at least single-motor failure, and most dual-motor failures, with either continuation of mission or abort to landing. BRS may be present, but the FAA is not currently enthusiastic about using parachutes for ELOS (thanks Cirrus!), so the designs I'm familiar with take no safety credit for the BRS. This is the reason that manned eVTOLs have at least six independent lift fans (multiple motors on shaft still have enough common modes to not get much credit), and usually optimize at 8 - 12.
 

addaon

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I don't have numbers for helicopters, but for variable-pitched propellers on fixed wings it may be higher than you expect. Certainly same order of magnitude as failure of a redundantly-wound electric motor. See AC 35-1A for some actual numbers; paragraph 3.1.6.1 recommends a per-effect failure rate of 10^-7 for hazardous effects, which would include a thrown blade by 3.1.3.2.
 

Dan Thomas

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I don't have numbers for helicopters, but for variable-pitched propellers on fixed wings it may be higher than you expect. Certainly same order of magnitude as failure of a redundantly-wound electric motor. See AC 35-1A for some actual numbers; paragraph 3.1.6.1 recommends a per-effect failure rate of 10^-7 for hazardous effects, which would include a thrown blade by 3.1.3.2.
In 49 years of aviation I have heard of maybe one thrown helicopter blade. There must be more, but power or control failures would be far more common.
 
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addaon

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The must be more, but power or control failures would be far more common.
Absolutely agreed today, but this is an area where electric is just flat-out better. Individual components are more reliable in an electric motor driven system than a turbine or piston engine driven system, both in engine/motor and in connected components due to lower vibration and greater control of torque rates; and it's much, much easier to build redundancies into the system.
 

dave wolfe

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My big worry is a flock of birds, like the one that made the saudi vtol crash. Its doable, for sure, at the cost of heavier props and stuff.

Lightning, too, seeing how its all electrical.
 

addaon

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Yeah. One bird you deal with by redundancy... a whole flock you deal with by reducing exposure. And having that no-credit BRS. As we've seen, even Part 25 can't do all that much given a flock of geese.
 

D Hillberg

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Yeah. One bird you deal with by redundancy... a whole flock you deal with by reducing exposure. And having that no-credit BRS. As we've seen, even Part 25 can't do all that much given a flock of geese.
Look up the old Stanley escape systems. It chucks out the pilot at 0 0 -
A tractor rocket attached to his parashoot
Mr Toads Wild Ride
 

jedi

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Yeah. One bird you deal with by redundancy... a whole flock you deal with by reducing exposure. And having that no-credit BRS. As we've seen, even Part 25 can't do all that much given a flock of geese.
“One bird you deal with by redundancy... a whole flock…..”

I assume you are thinking of Sully’s ride. They had wings and all were able to walk (or swim if they wanted to) away. As they any landing you can walk away from is ok.
 
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