Raptor Composite Aircraft

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Turd Ferguson

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Do they actually make the swing arm pivot coincident with the drive pulley? If yes, that is way simpler than the tensioner but really puts a premium on keeping belt tension in the right range...
HD drive pulley is not on the swing arm pivot and the final belt drive uses no belt tensioning device. The do have the geometry set up so the belt is at maximum tension in the normal riding position (swing arm pivot in line with drive pulley center and rear axle bolt. The belt tension changes very little as the suspension moves through it's travel. The belt tension is set by deflection so it's sorta like tensioning control cables on an airplane.
 

Toobuilder

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The HD example is valid in the fact that the big bore bikes have the transmission divorced from the engine. Further, the trans is bolted rigidly to the frame while the engine is rubber mounted. I believe there are heim links that constrain engine movement in certain axis, but it is free to move quite a bit relative to the trans. And the primary drive is a wide, toothed belt. I wonder how they make that work?

However, the engineering challenges that HD overcame cost time, money and weight solving an issue that Raptor does not have - bolting a PSRU directly to the engine is the way to go here.
 

flywheel1935

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ppdrive.jpeg smartp.jpeg
That comment makes sense. But, your earlier comment "...Peters complete lack of understanding in that the PRU must be integrated into the Engine Structure..." doesn't make sense to me. I used the P-39 as an example but others have pointed out that many (most?) helicopters have reduction units separate from their engine(s).
Hi Bert, I'll dig out a photo or two of what I was trying to explain, then you'll get an idea I was trying to explain in words .
 

bmcj

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Always some form of Guibo (just learned that word, thanks)
I’ve never heard that word either, but looked it up and it said that you (and countless others transposed the “IU”, with the correct spelling being “Giubo” with a pronunciation of JOO-boh.
 

Bert

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View attachment 89670 View attachment 89671

Hi Bert, I'll dig out a photo or two of what I was trying to explain, then you'll get an idea I was trying to explain in words .
Thanks for the clarification. These are the types that I see most commonly - either belt or gear driven. And, that is what you see in most certified engines (GO- or GIO-) where the gear box is bolted directly to or is actually part of the engine block. I was just a bit taken aback by your comment that the reduction unit must be connected directly to the engine block. There are many instances of where that is not true.
 

Toobuilder

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I dunno which models still use a belt but HD has mostly gone back to a double row chain for primary drive.
Yep. And even the belt models have a rigid link to the trans to keep the sprockets in alignment. That's what I get for going off flawed memory.

Disregard my earlier post
 

Jay Kempf

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Awesome. The best forums I have every been on research terms and correct spelling and context. How we learn. Thanks. "Giubo" is not going to get spelled right after being beaten into phonetic spelling in the 60's. I still battle with spelling. Computers help sometimes and not others.

I want it to be Guibo the killer pimp being a Risky Business 928 owning fan.
 

Jay Kempf

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I think motorcycle style drive belts have both cogs deeply flanged. Normal belt installation would only have the drive cog flanged and the others not which allows the position of the drive cog to position the belt axially. When you have this setup and you rely on idlers and one of the bearings in the system goes it normally spits the belt due to angular slop. With all guide belts and rollers flanged it is less likely. In a timing belt you can't slip a tooth and have the engine survive (depending on interference or not) but in a rear drive belt like in an HD you can skip teeth and nothing happens other than skipping in the drive which is just an indicator of wear. The prop doesn't stop in other words.
 

bmcj

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Awesome. The best forums I have every been on research terms and correct spelling and context. How we learn. Thanks. "Giubo" is not going to get spelled right after being beaten into phonetic spelling in the 60's. I still battle with spelling. Computers help sometimes and not others.

I want it to be Guibo the killer pimp being a Risky Business 928 owning fan.
That’s OK, sometimes I still struggle with “guarantee” vs “gaurantee” and have to write it out and look at it first to be certain.
 

flywheel1935

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Thanks for the clarification. These are the types that I see most commonly - either belt or gear driven. And, that is what you see in most certified engines (GO- or GIO-) where the gear box is bolted directly to or is actually part of the engine block. I was just a bit taken aback by your comment that the reduction unit must be connected directly to the engine block. There are many instances of where that is not true.
Hi Bert, I meant only in relation to the Raptor project, As it has enough issues with its design & construction already, and more importantly is a "commercial venture."
 

BBerson

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The prop is very far back and it is sort of remote mounted. Not sure why, I suppose to get the prop away from the wing wake.
Moving the prop closer would help with the aft CG problem. Almost any structure added to keep the cogs in alignment will add more aft weight and moment. A new PSRU with bearings on both sides of the cogs is needed, I think.
 

Ethan Johnk

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I've read with great interest for a while now and appreciate the knowledge present on this forum and how it could be used in this project.
As far as Harleys go the engine/trans unit has always been more or less treated as a unit and used a chain primary. Primary belts are a more custom application. The belt drive to the rear wheel uses no Guibo (cush). Interestingly canam spyders use a single flanged sprocket that when properly adjusted, rides in the center and does not contact the inside flange at all. The latest engine (three cylinder) has had issues with an uncomfortable vibration at certain rpm/road speed combinations which was fixed by adding a idler pulley- not to tension, but to change the vibration characteristics of the final drive.
Peters drive does not have much going for as far as sound mechanical principles go.
I find it interesting that of what he shares on yt the engine is never at 100% power for more than a few seconds. Its always a slow increase to full power with egts climbing unarrested until well after he closes the throttle.
 

BoKu

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Thanks for the clarification. These are the types that I see most commonly - either belt or gear driven. And, that is what you see in most certified engines (GO- or GIO-) where the gear box is bolted directly to or is actually part of the engine block. I was just a bit taken aback by your comment that the reduction unit must be connected directly to the engine block. There are many instances of where that is not true.
Sure. A good example of that is the Lockheed Electra. Look up "whirl mode flutter." It can be done, but it's best done carefully.
 
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