Yamaha 120hp ygs psru coming soon

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Chopndrag

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Well I seriously contemplated putting a gearbox and the whole ordeal on a yamaha 120hp genesis. I know everyone is doing the yg4 150hp but neither of my planes need that power and I see more need for something simple for the 3 cylinder. I've already started with developing a simple bolt on belt drive and hopefully will be out in a couple months .
 

Vigilant1

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Great, post more as the project develops.
I'd prefer the 4 cylinder, just based on vibration/firing pulses. IIRC, their 4 cyl 150hp yg4 weighs about 125 lbs--bare--which seems pretty darn good. . How much does the 3 cylinder weigh?
Anyway, if you can make the 3 cylinder work and it has some advantages (cost? packaging? weight? availability?) than that will be great.
 

Chopndrag

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My hanger neighbor is running a 3 cylinder in his gyrocopter and has about 100hrs on it . The engine performs great and there isn't that much in vibration compared to a 582. Once it gets off idle it smooths right out . He recently switched to a clutch and it works even better buuut he doesn't like the fact that it's like a provision 4 holding it all together. Weight of both motors is about the same . I just have no use for a 150hp engine in my plane and have access to a 3 cylinder which is also a great motor. I'm doing this for myself and if anyone wants to buy one that works too. As for cost I have no idea yet but we're shooting for a full bolt on kit no strings attached at max $2000 .
 

Chopndrag

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Well we're under way . Hopefully this coming weekend I'll have the drawings done for the belt drive mount plate. Tje rest should be easy after that.
 

Chopndrag

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Luckily I have access to a very talented cnc programmer with all the equipment to make it happen. If I can't find pulleys that will work for the project he can make those too. I would rather not have to make them but if so that's also covered. I keep hearing it can't be done without a clutch but I've personally seen them ran without one . You gotta tune the carbs and stay off idle like a 2 stroke and it runs fine .
 

wsimpso1

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Well I seriously contemplated putting a gearbox and the whole ordeal on a yamaha 120hp genesis. I know everyone is doing the yg4 150hp but neither of my planes need that power and I see more need for something simple for the 3 cylinder. I've already started with developing a simple bolt on belt drive and hopefully will be out in a couple months .
What is the intended range of rpm and engine output of this system? What prop flange are you using? What is the maximum and minimum prop inertia for the system? Perhaps you have recommended props? What is weight of the completed system?

Now on to how you know it will be reliable. How are you planning to demonstrate adequate useful life and reliability? Is it a torsionally "soft" system or a "stiff" system? How did you or how do you plan to verify that it does not have any issues with durability and specifically, with torsional resonance over its intended operating range and lifetime?

Billski
 

Chopndrag

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Crank spins at 8500 rpm reduction will bring it to 2500-2600 rpm prop speed . Will be shooting for a 3:1 ratio using a 72" warp drive 3 blade tapered tip. The design is based off of what the raf2000 gyrocopters have been using for over 20 years . Do I have all the exact details hell no but I do have a **** good idea of how it should be built considering my hanger neighbor is running the same motor and I got direct information off him . I'm an idea man and fabricator . I don't need all the fancy numbers just the basics . After the redrive is built it'll be ground ran in a stand for hours and hours before it even goes in my plane . That being said this is experimental aircraft no need to try and bust balls because someone is thinking outside of the box .
 

Marc Bourget

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" I don't need all the fancy numbers just the basics ."

I think that could have been one of the last thoughts of the BD-10 pilot before his last flight!

John Thorp, responding to the reply "Well, so and so's been doing that for years", would give a "Cheshire Cat" grin and remark, "Well, I guess his luck hasn't run out . . yet!"

Please do yourself the favor of giving careful consideration of the suggestions Billski has made for your benefit. TLJAR can turn around and bite you in the behind too fast to flinch!

"Bust balls"? Gosh that sounds defensive to me. I've been following this forum for awhile and I don't recall seeing anyone lurking about just to bust balls. I may have made comments perceived by others in the same way, but, if any balls were being busted, they were mine - as I was reliving my previous mistakes and re-punishing myself for lack of intellectual honesty and common sense. So far, I've survived my goofs, so far!
 

TFF

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I think this is the two sides of the coin of homebuilding. Billski is a professional engineer that spent his life in the transmission field. He does know what he is talking about. He also checks everything because that is what his life has been about. The other side is just build it. That is what homebuilding was built on. People being able to express what they want is what it's about. While hedging your bets with some numbers is probably smart, building it and testing it till it blows up is just another way to skin the cat. Best though is not talk about it until you are running, around here. Words are the only game on the internet. Doers should do first, then explain later.
 

TJay

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" I don't need all the fancy numbers just the basics ."

I think that could have been one of the last thoughts of the BD-10 pilot before his last flight!

Lol not sure that is a fair comparison. Belt drive vs a Jet.

If the belt drive fails Just land the airplane.

I'm with chop and drag here Just build it and see if it works.

What direction will this system make the prop spin?
 
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Chopndrag

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Lots of activity on the avidfoxflyer fourms about these type engines.

Where have you been?
Let's get a few things straight. I may not have a degree as a engineer but I have been building aircraft for 22 years. Started with a belt driven raf2000 gyrocopter. I'm basing my belt drive off of a proven design and making a system that is easier to install for the average person. Now comparing jets to a belt drive is just apples and oranges . I'm not going to throw the belt drive in and go . If you read everything I'll be running the crap out of it on a stand until I feel it's safe to put in my plane. If it doesn't work oh well no harm no foul , that's the nice thing about having access to a full machine shop with engineers. I bring an idea we make it and see how it goes. Hey TJay I've been mia working on my plane for the last year doing a ton of new and different stuff to it . I have seen the posts about the yamaha there but it's for the 150hp and not the 120hp. I just don't feel the need for 150hp in my little avid and saw barely anyone doing anything about the 120. My hanger neighbor has been running the 120 for about 100 hours and loves it but hates the hassle he went through to go gearbox so I decided to TRY a belt drive system . I'm using successful numbers from someone running one and designing around first hand information. If NASA can trust me to build stuff for the Space Station along with the military I think I can tackle a belt drive. Yes I said I think and that's because there's part of me thinking maybe it won't woek but that part is very slim. Belt drives have been running aircraft for thousands of hours so why wouldn't it work on a yamaha ?
 

wsimpso1

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Crank spins at 8500 rpm reduction will bring it to 2500-2600 rpm prop speed . Will be shooting for a 3:1 ratio using a 72" warp drive 3 blade tapered tip. The design is based off of what the raf2000 gyrocopters have been using for over 20 years . Do I have all the exact details hell no but I do have a **** good idea of how it should be built considering my hanger neighbor is running the same motor and I got direct information off him . I'm an idea man and fabricator . I don't need all the fancy numbers just the basics . After the redrive is built it'll be ground ran in a stand for hours and hours before it even goes in my plane . That being said this is experimental aircraft no need to try and bust balls because someone is thinking outside of the box .
No design effort yet, no analytical proveout, empirical proveout of just hours. Your proveout will be almost entirely in-flight with risk to life and limb. I will not go near it, and neither should anyone I care about until you have several each running a couple hundred hours of full operation cycles.

If you are copying another well proven system, well, you had better copy it exactly. You have no idea which features they put in for no specific reason, and which they had to work up to by build and test cycles.

Have fun and hope no one gets hurt.

I have worked with powertrains where the folks involved have underestimated the difficulty of their issues. This sounds eerily familiar. Those folks had huge surprises, including one aviation system that tore itself and its test stand to pieces when it broke. Everyone was really glad that did not happen in flight, I am here to tell you.

By the way, 8500/2600 is 3.27:1. That 3.0:1 will put your engine at 7800 rpm when the prop hits 2600 or your prop will reach 2833 when the engine gets to 8500 rpm. You will need to get closer on gear ratio than that. You might consider sprockets with number of teeth at prime numbers for both sprockets to keep belts and sprockets out of resonance.

Billski
 
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wsimpso1

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The other side is just build it. That is what homebuilding was built on. People being able to express what they want is what it's about. While hedging your bets with some numbers is probably smart, building it and testing it till it blows up is just another way to skin the cat.
First point: I must say that while Curtis Pitts, Paul Poberezny, and Steve Wittman (heroes all) may never have been degreed engineers, they were very competent about applying known design features and sizing to their designs. Curtis Pitts even had the foresight to have degreed folks analyze his work. That is a long ways from just guessing...

Second point: Testing until it blows up is smart. Testing it for "hours" sounds like running a few power settings, getting the fuel and spark set right, and saying "that is good enough". Nope, hundreds of hours running from idle to max and back to idle with a lot of that time at settings for each of max, cruise, descent, idle and slow sweeps up through the entire range begins to sound like a test scheme. Make sure you have enough pitch on the prop to load up the engine. Maybe run some whole cycles with a prop at each of lower and higher inertia than you plan to use just to make sure you have resonance out of reach. Now that is testing until it blows up or makes you believe it is sturdy by it just running...

Billski
 

wsimpso1

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If the belt drive fails Just land the airplane.
Two problems with this philosophy:

Some fraction of dead stick landings will always tear up the airplane, hurt people, or both, no matter how well you prepare for it;

Who says that the failures you get will not tear up other stuff on the bird? He is not intending to design for robustness to put all other failure modes out of reach. He will be exposed to broken sprockets, shafts, housings as well as the belt, each possible failure resulting in the prop and maybe the belt thrashing about, potentially cutting or otherwise damaging airframe systems or the pilot. That forced landing could get difficult indeed if the airplane does not answer your control inputs, noses over abruptly, tumbles, or injures you.

Billski
 

Chopndrag

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How do you know there's been no design effort. are you psychic ? If so please tell the everyone when the world will end . I've already stated it will be ran on the ground on a test stand for a loooong time before I even consider putting it in a plane . Just because someone doesn't disclose all there educational experience doesn't mean I don't know what I'm doing. I've been around high hp belt drives for 22 years and have a pretty good idea on how they work . No I don't have all the answers but that's why I love experimental aircraft. Notice the last part is mental ? Some people have to be mental to sometimes break ground. If it doesn't work so be it I'll even admit to failure it doesn't bother me . I'll even post up that it didn't work . The gear ratio was a starting point we did talk about 3.5 :1 as a better starting point then 3:1 . I run that ratio on my rotax now and like it so that was my first idea . I talked to my buddy running the yamaha next to me and he said 3.5 would be a better start . Ohhh he's an engineer too forgot that part and he comes to me to help solve his problems so what's that say ? Is he dumb not by far am I ehhh jury is out on that but he trusts me and I trust him . He even said he would love a belt drive and fully supports my hairbrained idea.
 

pictsidhe

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I'm with Bill, redrives are not as simple as they seem.
We don't doubt your abilities to build something to spec, we are dubious about anybody being able to just guess those specs.
 
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