Yamaha Genesis 120hp engine

helicopter ed

helicopter ed
Joined
Nov 8, 2010
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Hamilton, Oh
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Gyrochopper1/Air Comm. single/AC side by side/AC tandem. All powered by Subaru EA-81 100 HP
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4000+ all rotorcraft.
My hat is off to you Racer, You sound like me 30+ years ago, I want to have you as a friend. All that power is not a problem to a careful pilot. On a 4 stroke you can pitch that big beautiful 68" Warp 3 blade way up there 15 to 17 degrees on the tips WHICH WILL lower the NOISE a bunch and get fantastic GPH usage, way under 5 GPH, WAY UNDER. And still have plenty of power on single place.
I lowered a stock Sub. EA-81 direct drive with 60" 2 blade Warp to full power 2600 RPM"s and 2200 cruise at 55 MPH, uses only 2 1/2 GPH. [same RPM"s as Lyco. or Cont.]
On 2 place Sub. EA-81 with 2 to 1 redrive, most would scream it 5500 RPM"s and more, I limit both my trainers to 4400 full power, and 3600 cruse at 55 MPH. [More pitch and quieter. Props make 4 times more noise then a straight exhaust.
this thread you started on your Yamaha eng, project has more interest then anything I have seen lately. Thank you... helled1
 
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Jason O

Junior Member
Joined
Jun 13, 2007
Messages
541
Location
Portland
I never ran it without the clutch. I Know that both Ron and Todd ran their engines without the clutch and from those expierences, they determined that a clutch was necessary. I do believe that they were using something close to the stock rotax flywheel and using the stock Rotax rubber donut.

From my expierences with a BMW engine, I would use the heaviest flywheel that you can stand and work my way down from there, not the lightest one and work your way up. I believe that a heavy flywheel will really make your installation have a better chance of success right off the bat

Jason

Jason,
Did you have to run the clutch or could you have run it with just the Lovejoy coupling?
 

Racer

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Colorado Springs, Colorado USA
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Air Command CLT N7512X
I never ran it without the clutch. I Know that both Ron and Todd ran their engines without the clutch and from those expierences, they determined that a clutch was necessary. I do believe that they were using something close to the stock rotax flywheel and using the stock Rotax rubber donut.
Jason

You are 100% correct Jason
The yamaha clutch pack assembly is almost 4 pounds heavier than the stock Rotax flywheel/rubber donut combo so therefore it is more rotating mass which works pretty good as a flywheel.

PS I have 96 hours on my drivebody/clutch assembly with no signs of failure as of yet.
 

GyroRon

Former Gyro know it all
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Hello Ron,

How many hours since you replaced a clutch?

Jason

First off, my clutch has never failed. What was happening was the grooves the springs ride in broke apart on the first set of shoes at about 60 hours tt, and the clutch would not disengage fully. It still turned the prop and still flew just fine. Matter of fact, the whole time I was in florida at Bensen Days last year, the clutch had this issue, yet I flew another 15 or so hours while there with my " broken " clutch.

at about 75 hours tt I replaced the clutch shoes and springs with a new set. That lasted all of about 30 minutes before the clutch was dragging again and Once I tore it apart I discovered on of the springs had broke. I had flown it another 4-5 hours that day of the spring failure before I took it apart.

At roughly 80 hours tt, I took the gyro out of service and decided to replace the entire clutch assembly. I pulled my old clutch drive body off, and installed one of Racers centering rings on my engine back plate. Airscooter then took my old clutch drive body and after a few months made up a batch of new ones, Hardened and with closer tolerances that Racer specified. When airscooter came out to install the drive body we ran a dial indicator on it and it was serverely out of round. He pulled it off and a few weeks later brought me another one to try out. It too was not perfectly straight and true, but was within comfortable tolerances. I installed a new set of shoes and springs and bolted it all up and so far it has gone almost 18 hours without failure.

My gyro hasn't flown since late October, the exhaust has had some leaks in it and I have been too busy to work on it till now. I have a list of things on the gyro to do besides the exhaust in prep for it's annual condition inspection. Pulling the gearbox and inspecting the clutch is on my list of things to do.
 

Jason O

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Jun 13, 2007
Messages
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Location
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Failure mode

Failure mode

Hello All,

I have said it before, but I would like to make it perfectly clear that when I say the clutch failed, I am saying it needed to be replaced. The "failure" mode of this part is very slow and shows signs way before it is a non working part. To my knowlege, there has never been a loss of propulsion caused by the clutch wearing out. It looks like Todd has almost 100 hours on his clutch and it does not need to be replaced so it is possible that the problem has been solved. The Yamaha 3 cyl 4 stroke is a great engine and Todd has done a great job of putting together a kit that (as far as alternate engines go) has had a minimum amout of minor problems. As with all engine/redrive combinations, the ONLY way to tell how it will work is build hours flying and the fleet of Yamahas is rapidly doing that.

Jason

First off, my clutch has never failed. What was happening was the grooves the springs ride in broke apart on the first set of shoes at about 60 hours tt, and the clutch would not disengage fully. It still turned the prop and still flew just fine. Matter of fact, the whole time I was in florida at Bensen Days last year, the clutch had this issue, yet I flew another 15 or so hours while there with my " broken " clutch.

at about 75 hours tt I replaced the clutch shoes and springs with a new set. That lasted all of about 30 minutes before the clutch was dragging again and Once I tore it apart I discovered on of the springs had broke. I had flown it another 4-5 hours that day of the spring failure before I took it apart.

At roughly 80 hours tt, I took the gyro out of service and decided to replace the entire clutch assembly. I pulled my old clutch drive body off, and installed one of Racers centering rings on my engine back plate. Airscooter then took my old clutch drive body and after a few months made up a batch of new ones, Hardened and with closer tolerances that Racer specified. When airscooter came out to install the drive body we ran a dial indicator on it and it was serverely out of round. He pulled it off and a few weeks later brought me another one to try out. It too was not perfectly straight and true, but was within comfortable tolerances. I installed a new set of shoes and springs and bolted it all up and so far it has gone almost 18 hours without failure.

My gyro hasn't flown since late October, the exhaust has had some leaks in it and I have been too busy to work on it till now. I have a list of things on the gyro to do besides the exhaust in prep for it's annual condition inspection. Pulling the gearbox and inspecting the clutch is on my list of things to do.
 

All_In

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Good to know it has been solved, and thank you for keeping us informed!
It looks like this is a winner to me, so far!
Way to go Todd!!
 

Friendly

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Woodworth, LA.
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Todd,
How much difference is there in the weight of the Yamaha clutch and the clutch you are using?
What happens when you run it without the clutch. Does the engine shutter like it cannot get up to speed to idle?
 

NoWingsAttached

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Columbia, SC
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Todd:

Exactly what is used as the clutch? I see "Yamaha clutch" written here, what is that? Really a Yamaha clutch? What is used for originally?

Greg
 

mcbirdman

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Grand Ledge (Lansing) Michigan
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As I understand it the problem arises from swinging a large prop at low rpm. Problem doesn't occur when engine is in snowmobile. The centrigugal clutch/belt essentially disconects the engine at idle from a load. This allows the crank to adjust rotation speeds without hesitation. A prop mounted to this engine would have either had to idle much faster than anyone would desire to smooth out the power pulses or needed to be disconnected from the engine at low speeds.

In this case a new clutch system was designed that is smaller and lighter - specifically for aviation use.
 

mcbirdman

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lw3 sp long, lw3 2place long yami
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Hi Todd
In post 139 WAYYY back you talked about the use of the belt reduction unit. Did you ever make any feasability descisions? Just wondering if it was possible to get the desired prop rpms out of this setup and if so - wouldn't this be a realitively easy way to achieve a higher thrustline tractor configuration package?

repost of the photo:
 

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Russ Hobbs

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Attention Airscooter
I paid for two clutch upgrades that you promised to build. I've been patient but it almost summer and I'm still waiting. Todd has been trying to make contact with you to resolve the issue. if you don't have time, please return the $1400.00 dollar's so I can contract with someone else. Thanks and no hard feelings, but I'm getting excited now that the weather is warming up.
Russ
 

Friendly

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Hi Todd
In post 139 WAYYY back you talked about the use of the belt reduction unit. Did you ever make any feasability descisions? Just wondering if it was possible to get the desired prop rpms out of this setup and if so - wouldn't this be a realitively easy way to achieve a higher thrustline tractor configuration package?

repost of the photo:

What is that V4 out of? What engine is it? and do you know the weight of the stock snowmobile clutch?
 

mcbirdman

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Mark, that is just a photo that Racer posted way back on post 139. I don't know. He was talking about a possible adaptation using snowmobile clutch.

I am sure it is heavier than the existing prop clutch, likely significant. There are some definate performance and design advantages to consider for a tractor installation.
 

Jason O

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Joined
Jun 13, 2007
Messages
541
Location
Portland
Clutch used on the Yamaha

Clutch used on the Yamaha

The clutch used is an RK 400 clutch used on rotax 2 strokes for the exact same reason we use it on a Yamaha. The clutch is designed to replace the stock flywheel and rubber donut in a Rotax C gearbox. The part attached to the crank (clutch shoe holder) has been redesigned by Todd to match up to the Yamaha crank. The clutch shoes and Gearbox side of the clutch is the stock unit provided by Air-Tech. Attached is a link to the clutch at Air-Tech.

http://www.air-techinc.com/catlist.asp?categoryID=atclutch&typ=Exclusives

Jason

Todd:

Exactly what is used as the clutch? I see "Yamaha clutch" written here, what is that? Really a Yamaha clutch? What is used for originally?

Greg
 

AirScooter

Scott Waggoner
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Attention Russ Hobbs,

I owe Racer three hubs. But YOU I do not know. And you have NEVER paid me for anything. Racer is the only person who has paid me for a clutch part EVER. I will be sending Racer his parts as soon as I can as they are complete and modified again. And by the way if you paid 1400.00 for two to anyone, shame on you, I charge roughly 350.00 each depending on freight. This is exactly why I hardly ever get on here anymore, either a bunch of high school girl drama based on non facts or the other scenario seems to be a clique of people attacking an individual and then the clique hugs and sings kum bay ya.

Good day.
 

Russ Hobbs

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Air scooter, I re-read my post, my apologies. I didn't mean it to sound like I was attacking you. I meant to say I prepaid for those clutches and had hoped to have them installed on my motors by know. If you could find the time I would be most appreciative, if not I understand, and will have them built elsewhere. Please except my apologies and let me know how you would like to proceed.
Russ
 
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