Vibration dampening

[bentwings2]

bifilar counterweights I finally found the name of what I was looking for. bifilar counter Weights weights or vibration damper. This came abou5 in m6 search for information on the P&w R 4360 aircraft engine from WW2. The engine had a nasty vibration and these counter weights.

Now the question is
More or less cured it.

Now suppose the crankshaft weighed about 2,000 pounds. If I were to make a scaled down model say 2 pounds. Would this type of balancing weight scale in size and weight? I can create the parts but are they necessary. The crank speed would only be maybe 4,000 rpm. All the rotating and reciprocating parts would be scaled by size no5 necessarily weight. I could balance the assemble very close just turning between centers but dynamically I will not have equipment for this. Since materials would be nearly identical. Size would have a great advantage in strength it would Be nice not to have to make the balance weights and design in the shape.

 

[GregLocock]

This is a harmonic damper on the crank web? I don't think you'll need them, as engines get smaller the resonant frequencies get higher, so if you are running at lowish rpm I expect you'll be ok.
Here's an example

https://www.chegg.com/homework-help...pter-5-problem-43p-solution-9780136510680-exc

Here's what I initially guessed you were talking about, these things are hilarious

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.561.3228&rep=rep1&type=pdf

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[bentwings2]

I think that answers the real question....does vibration dynamics “scale Down”. I would think not when you look at small engines their internal are massive compared to larger engines.ive only blown one model airplane engine up to total destruction. It had a big load of nitro in it and it was running at least three times the recommended rpm. It blew the entire cylinder of at the bottom of the cylinder sleeve. Ironically the crank still turned,,,, not much was still attached. I blew up my shar3 of drag race motors but when you play with nitro ....as they say.......happens.

Thanks for the answer.

 

[WKTaylor]

Bifilar are also used in Helo Rotor systems at the 'congested' areas at the rotor hubs.

Here are some illustrations for Sikorsky bifilar designs...

https://www.google.com/search?sourc...AQdnd3Mtd2l6&sclient=psy-ab#spf=1595371348788

https://www.google.com/search?sourc...qAhVxMX0KHR8iA3kQsAR6BAgKEAE&biw=1920&bih=911

Regards, Wil Taylor
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