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JP wrote:
> "George" <gvig01@sbcglobal.net> kirjoitti
> viestissä:ZwPYf.8803$%m4.7457@newssvr33.news.prodigy.com...
>> Richard Lamb wrote:
>>> ADK wrote:
>>>
>>>> IF you had to design a PSRU, to drive a pusher propellor via shaft, what
>>>> would your experience dictate? Thinking along the lines of a gearbelt,
>>>> chain or gear. Please, I'd appreciate the collective experience
>>>> available on this group. I've decided on the aircraft, but want to
>>>> make it the most reliable and safest it can be.
>>>>
>>>> "ADK" <aklettke@okanagan.net> wrote in message
>>>> news:X6TXf.28774$%H.11944@clgrps13...
>>>>
>>>>> This is probably going to open old wounds. What I'd like is
>>>>> experienced input on the advantages, for economic, efficiency and
>>>>> longevity etc. of different types of redrives.
>>>>>
>>>>> I'm leaning towards a cog-belt reducer in a 6 cylinder, liquid cooled,
>>>>> configuration driving a long drive shaft to the prop.
>>>>>
>>>>
>>>>
>>> The collective experience is zilch = nada = squat = undefined.
>>>
>>> THAT is what everybody had been trying to tell you.
>>>
>>> Wait a second. Look around the airport.
>>>
>>> How many shaft driven propellers do you see?
>>>
>>> Have you ever seen?
>>>
>>> If you are heart set on doing it, I sincerely wish you luck.
>>>
>>> But I cannot offer any further advice - 'cuz they ain't none...
>>>
>>>
>>>
>>> Richard
>>>
>>>
>> Richard,
>>
>> Didn't the military do this once?? Seems there was the P-39 Aircobra,
>> shaft driven from a rear mounted engine?? Are the gray cells working that
>> far back??
>>
>> Not that it would be applicable to an experimental, but at least It was
>> once done?
>>
>> George
>
>
>
> The P-39/P-63 examples cannot probably be compared directly with this matter
> in question. These designs both have a large reduction gear casing in front
> of the plane. The support structure for this PSRU looks very firm. Perhaps
> the safety cage type center fuselage structure has something to do with the
> lack of severe resonance problems? Any known resonance problems with these
> aircrafts?
>
> JP
>
>
I find myself wondering if, even though the P-39/63 cannot be directly
applicable to experimental class aircraft, is not there a lesson to be
learned here.
The primary shart turns at engine speed, the PSRU is located remotely
and the propeller isn't transmitting torsional resonant frequency
pulses to the shaft. At least not directly. Would a pulse absorbing
coupling, such as Molt used, totally eliminate the resonant frequencies
in the shaft??
Since the OP was thinking of a remote mounted engine and a long shaft,
is this worth considering, since he seems bent on exploring this
possibility??
Just my mental ruminatings. YMMV
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Re: PSRU design advantages
