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How would one of the composite props, such as an IVO or Warp drive fair in
an application such as I've described? Especially using a 3 or 4 blade
prop.
Also I want to use a segmented drive shaft so that each of two sections are
reduced in length over a single long shaft.
Would not using a 6 cylinder higher reving engine also be an advantage over
a lycoming for torsional vibration or would the concern only change in
frequency?
"Peter Dohm" <lefty133@bellsouth.net> wrote in message
news:3lUXf.5701$z7.1213@bignews3.bellsouth.net...
>
> "Morgans" <jessmorgan@cJhUaNrKter.net> wrote in message
> news:zjTXf.291$38.91@fe07.lga...
>>
>> "ADK" <aklettke@okanagan.net> wrote in message
>> news:X6TXf.28774$%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.
>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>
>> Warning,Warning, Danger, Danger, Will Robinson!
>>
>> Yep, that is a really big can of worms.
>>
>> The redrive isn't as big a problem as you think. You get into a mess
> when
>> you start talking about long drive shafts.
>>
>> Torsional resonance has brought many of the great minds of the flying
>> industry to their knees. No joke. I do not have all of the links at
>> hand,
>> but someone here does. Start by googling torsional resonance.
>>
>> Then, be afraid. Be very afraid.
>> I you do not get afraid, keep looking, until you get afraid, because you
> need
>> to get afraid, or you do not understand the problem.
>> --
>> Jim in NC
>>
> Yes, Sir! Lots of old wounds, etc, etc ...
>
> Actually, I believe that a driveshaft can be part of the problem,
> solution,
> or both--although, in and of itself, I agree that a long driveshaft is far
> more likely to be a problem than a solution. Also, do not forget that all
> resonance applied through the engine mount to the airframe will still
> apply--there is a famous "Contact!" magazine article describing some of
> both
> problems during the [attempted] development of the BD-5. The point here
> is
> that, although a loss of power is the most obvious
>
> And keep in mind that, although the redrive isn't a source of torsional
> resonance, the redrive isn't inherently dampening. However, many
> redrives
> can be a source of considerable shear and bending loads applied to the
> crankshaft. I do not know how much is too much in either case.
>
> As additional food for thought: I was a long time advocate of automotive
> conversions, but I'm now leaning away from them--as well as from many of
> the more modern engine packages now available. I believe that they can be
> just about as reliable in service, and that the probable weight penalty is
> acceptable--if a slightly heavier airplane does the same job, burns a
> little
> more fuel, and has a lower initial cost; it may still be the best value,
> especially if you enjoy the education that you will achieve through the
> development work. However, I'm now leaning back toward the "traditional"
> type certified engines because it may be much easier to get approval for
> IFR
> operation. For some time to come, at least in the US, TFRs are going to
> continue as a fact of life; and an IFR flight plan gives that greatest
> assistance in staying out of difficulty on cross country flights. Just my
> $.02, and YMMV.
>
> Peter
>
>
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Re: PSRU design advantages
