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Re: [Land-speed] Multiple Engines

To: "John Burk" <joyseydevil@comcast.net>, "LandSpeed List"
Subject: Re: [Land-speed] Multiple Engines
From: "23weldon" <23.weldon@comcast.net>
Date: Tue, 23 Mar 2010 20:17:48 -0700
Sparky and others --
My thought on this is that more torsional dampening in the form of a better 
harmonic balancer might be what is called for.  Of course that is aside from 
the issues of misalignment between the two engines and Dave's suggestion to 
put in a 45 degree separation between the two engines to smooth out the 
torque peaks. But be careful with this.  Such a proposal can double the 
forcing frequency and put it closer to one of the new vibration mode 
frequencies than you want.
I do think that I'd want someone else's experience with the coupling of two 
engines as an example to follow or a benchmark.  Lacking that I'd spend some 
time relearning the methodology of torsional vibration analysis I learned in 
my mechanical vibrations course some 50 years ago and promptly forgot.  At 
the time the hot setup was a tabular calculation protocol known as Holzer's 
method.  http://www.sdrl.uc.edu/book/Chap-5.pdf  Den Hartog, pg 197
The right contact in the world of engine, turbine or other heavy rotating 
machinery engineering could provide access to modern computerized methods 
for torsional vibration analysis.  If you were to get into this your shop 
capabilities would likely make it possible to determine actual spring 
constants and moments of inertia that an engineer with the right software 
would need to begin the calculations.
Ed Weldon


----- Original Message ----- 
From: "John Burk" <joyseydevil@comcast.net>
To: "LandSpeed List" <Land-speed@autox.team.net>
Sent: Tuesday, March 23, 2010 5:41 PM
Subject: Re: [Land-speed] Multiple Engines


>I think crankshafts are stout to raise the harmonic frequency and resist 
>bending . For torque capacity think how small the transmission input shaft 
>is .
> John
>
>
>
>> List,
>>
>> When connecting two engines together at the crankshafts, what is the best 
>> offset to use? My thought is that harmonics should be arranged such that 
>> the rear crankshaft gets as little abuse as possible. Ideas?
>>
>> Thanks,
>> Skip
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