my gearbox first test run for V-twin engine

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karmarepair

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seems need to check the dynamic balance of the propeller , or and some kind of support for the protude part of the shaft.
Yes, the gearbox is moving around more than I would like to see, me.

It looks like you're doing this test in a public park! Bold! I can't make out if that is Chinese or Japanese on the trail marker in the right of the shot.
 

rv7charlie

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What does the engine's movement look like, 'live'? The motion in the video looks suspiciously like video 'artifacts', as we see in video of propellers when the 'shutter speed' of the video camera makes blades hovering in thin air. The frequency of the engine's movement seems way too slow to be directly related to a balance issue.

FWIW, an aircraft will dance around at low frequencies while doing a runup with the brakes locked. It's one of the things that make it more difficult to do a dynamic prop balance at near-cruise-power rpms while tied down on the ground. Turbulent airflow bounces the plane around, a lot.
 

howardyin

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What does the engine's movement look like, 'live'? The motion in the video looks suspiciously like video 'artifacts', as we see in video of propellers when the 'shutter speed' of the video camera makes blades hovering in thin air. The frequency of the engine's movement seems way too slow to be directly related to a balance issue.

FWIW, an aircraft will dance around at low frequencies while doing a runup with the brakes locked. It's one of the things that make it more difficult to do a dynamic prop balance at near-cruise-power rpms while tied down on the ground. Turbulent airflow bounces the plane around, a lot.
you are right, it still have a long way to go, hard works to do, just first step to something, now, it's nothing but a baby to me :)

this was the belt reduction unit test .the belt ruduction seems running smooth , so , I am wondering if I need adjust the surpport frame a litte forward to the gearbox will make it better.

A friend of mine have done the dynamic propeller balance to his plane , I will try later.

about on ground or in flight , did you guys ever have the dynamic prop check in air?
 
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howardyin

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Yes, the gearbox is moving around more than I would like to see, me.

It looks like you're doing this test in a public park! Bold! I can't make out if that is Chinese or Japanese on the trail marker in the right of the shot.
thank you for forewarn about safety。 the test site is end of a car road , almost no one pass by. In any case someone is going to pass by or geting near, we shut down the engine. we can not afford any safety loss to us or the third part .
 

TFF

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I have checked balance both ways, but a fixed pitch prop unloads in the air so you are better off flying and getting it to top rpm.
 

howardyin

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thanks, TFF! which meaure quipment you used to check the banlance in air?
 

BBerson

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The v-twin cannot be dynamically balanced much in my opinion.
(yes, get some some improvement at only one rpm) So why bother?
 

BBerson

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Dynavibe didn't work for me. Did you ever balance any engine with just one or two cylinders? The torque pulses are strong with the prop load.
 

FishHawk

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Can I ask you why did you choose a V-twin? I haven't built an airplane yet, but I've worked with many kinds of engines, and I hate V twins. The engines are so unbalanced that the engine mount bushings suffer, let alone in a place where balance is needed.
Why didn't you go with a parallel twin if you want a motorcycle engine? Even a single cylinder can have a dead weight counter balance to make it better than a v twin.
 

howardyin

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Can I ask you why did you choose a V-twin? I haven't built an airplane yet, but I've worked with many kinds of engines, and I hate V twins. The engines are so unbalanced that the engine mount bushings suffer, let alone in a place where balance is needed.
Why didn't you go with a parallel twin if you want a motorcycle engine? Even a single cylinder can have a dead weight counter balance to make it better than a v twin.
thanks for your info about V-twin. :)

3 reasons, 1 the engine have been put on homebuilt aready and tested (850cc, 65hp) by other homebuilters. 2 it 's convenient for me to get this engine and it is affordable 3, it seems (I am not sure , but just seems to me ) easy to be converted to airplane use.

BTW, working progress was painful slow :(

also , still studying the auto engines. after testing this gearbox, I will have try
 

rv7charlie

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It's a shame that we can't get those engines imported into the USA easily. The CanAm engines it's cloned from are just too expensive for me to justify for my purposes.
 

Vigilant1

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seems need to check the dynamic balance of the propeller , or and some kind of support for the protude part of the shaft.
Thanks for the video, looks like a good project.

You may already be well aware of this, but you might eventually want to see just how much power your projects are producing. An inexpensive and very accurate way to do this is with an "Eiffel Club", which goes by many other names ("Wood bar dynamometer", etc.). It just requires a few test "clubs" that you can make in an afternoon and a good way to get an RPM reading (which can be done with an optical unit looking at the spinning club). More on the process is at this thread.
Briggs vanguard conversions

From what I see of your video, the engine looks like it vibrates and rocks just as many other V-twins do. It is not ideal, but there are generally some RPMS that can be found where it isn't as noticeable.

If we were designing an engine just for airplane use, we probably wouldn't design it as a V-twin. But, if such an engine were just for airplane use, the market would be very small and their prices would, as a result, need to be expensive. The V-twins are made in huge numbers as consumer items, they are robust, pretty cheap, and can be bought new in a box shipped right to your door. So, maybe a little vibration can be overlooked if other things about them make them desirable.
 
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TFF

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Why did the dynavibe not work? Was it the dynavibe or just what you were trying to balance? I have only used one once, it was fine but not my favorite.
 
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