[HH] Mystery signal from a helicopter

[Greg London]

Jerry,

Thanks for the info!

I think I glommed rigid and semi-rigid together. Memory is turning to mush.

http://www.airspacemag.com/flight-today/how-things-work-ground-resonance-94660854/

"The only rotors that can produce ground resonance are those with three or
more blades."

I googled a bit to try and find that video. I thought it was a MASH
helicopter. maybe it was a brantly or a sikorsky 300. Couldn't find
anything that looked like either one.

Ah well. Won't be able to afford to fly anytime soon anyway.
Greg


> They used the Bell OH-13 (model 47) 2-bladed helicopter in M.A.S.H. The
> "killer Hillers" were two-bladed (semirigid) with wooden blades. I used
> to fly the Hiller OH-23 in flight school. Not only were they semirigid,
> but they had paddles connected to the cyclic and no hydraulics. The Bell
> had hydraulics.
> Bell OH 23
> *http://tinyurl.com/n5bmz6n
>
> *Hiller OS-23 Model 360
> http://www.youtube.com/watch?v=TRDJ9oyjcMc
>
> On 02/03/2014 12:13 PM, Greg London wrote:
>>> Most helicopters used by news organizations ...
>>> Depending on whether they are semi-rigit or fully
>>> articulated, each blade has its own independent angle of attack,.
>> Most news helicopters are Bell Jet Rangers with 2 rotor blades.
>> As far as I know, any helicopter with 2 rotor blades is rigid.
>>
>>> I have seen helicopters go into vibration on the
>>> ground and destroy themselves.
>> I've only seen video. It was an older Hiller "killer" model
>> (a la "M.A.S.H.") with 3 rotor blades.
>>
>> I've got a chunk of time on a Robbie.
>> Someday, I'll splurge and get an hour or two on something
>> with a turbine. If I win the lottery, jetpack.
>>
>> As for the article, interesting way to pack data in to the audio.
>> I wouldn't have been able to reverse engineer it the way the
>> guy writing the article did.
>>
>> Greg
>>
>>
>>
>>
>
> --
> Jerry Feldman <gaf at blu.org>
> Boston Linux and Unix
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