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Yamaha RX-1 Snowmobile Engine Conversion

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AIRCAB

Well-Known Member
Joined
Feb 6, 2015
Messages
89
Location
Vancouver Island
Marc, I do see that image, for the prototype RX1. I believe he now has moved away from that, and is producing a PSRU for the Apex model. This new PSRU uses a Spragg clutch. Am I wrong ?
 

Marc W

Well-Known Member
Joined
Mar 31, 2017
Messages
547
Location
Colorado
I believe you are correct. The Apex does still have the internal rubber damper on the output shaft.

There is an awareness in the Yamaha community that these engine/redrive setups are not proven. In fact, when somebody shows up on the Facebook site wanting to put one in some super whiz-bang model like a BD-5, they are usually told that the engine is unproven in aircraft and should be installed in an airplane that is capable of making an off airport landing. However, so far the engine/redrive combination has a good record. Time will tell!
 

Patrick Wehling

New Member
Joined
Apr 2, 2020
Messages
3
To Marc W: In your post of Feb 19,2020 you attached cover to aluminum plate that was chucked up in lathe chuck. You then got a better centering by using chuck jaws ( 4 jaws I guess). I am guessing that the chuck jaws secured the plate in a hole that you drilled in the plate that was roughly concentric with the cover hole. Does that sound right. Thankyou
 

Marc W

Well-Known Member
Joined
Mar 31, 2017
Messages
547
Location
Colorado
The plate has a block screwed to the back side. It must have been a jig or fixture in a machine shop. The other side is chewed up and full of holes. I don't remember where I got it. It's been in the scrap pile for years. I trimmed the plate to fit the swing of the lathe and clamped the block in the 4 jaw. This is why I never throw anything away! A man's wealth is measured by the quantity and quality of his junk!

I hope that answers your question.
 

Marc W

Well-Known Member
Joined
Mar 31, 2017
Messages
547
Location
Colorado
I don’t see anyone here cutting metal.
So said TFF in the new Yamaha thread. Herewith is what I have done recently on my Yamaha. I cut some 1/4" steel plate and bolted and tack welded it to my engine stand to give me a place to bolt an engine mount to. I also made a mockup of the firewall and mounted it on the stand.
1595360859901.png

I made spools for the engine mount to bolt to the firewall and have those mounted on my OSB "firewall. I am in the process of getting the engine lined up relative to the firewall so I can start cutting tubes for the engine mount. The stand I have the engine on doesn't work. The legs interfere with the engine stand so I need to make a stand at the right height to line up with the firewall.
1595361684767.png

Progress is slow since I haven't finished this years honey-do list. I fit in a little time now and then to work on it.
 

Marc W

Well-Known Member
Joined
Mar 31, 2017
Messages
547
Location
Colorado
The Thatcher was designed for the VW engines so whatever you can get from a VW seems to be OK. 80-85 hp?

The installed weight of the Rx-1 is a little less than my VW and it is real easy to limit hp. The density altitude when I flew Monday morning at sunrise was 7000' which is typical this time of year. The best I see here is 75% power on takeoff in the summer. I have to go to 11,000' plus to clear the low local mountains where power is down to 60 to 65%. You see where this is going! This is the land of big engines. 65 hp Cubs are scarce!

I don't know if this engine will go on the Thatcher. Maybe, but the VW is running fine. I am looking for a high wing project for the Yamaha. Right now, I am practicing welding and getting the intake and exhaust and cooling systems started. Just going to keep cutting metal.
 

BJC

Well-Known Member
HBA Supporter
Joined
Oct 7, 2013
Messages
11,993
Location
97FL, Florida, USA
Lighter than VW, more powerful than the VW, high DA operations all favor the Yamaha. I get it; just curious about the upper limit of HP that the Thatcher can use without structural / flutter concerns.


BJC
 

Marc W

Well-Known Member
Joined
Mar 31, 2017
Messages
547
Location
Colorado
Yes, it is a concern. If I do put it in the Thatcher, I will put a throttle stop on it to avoid over stressing the airframe.

Myself and another pilot with a Sonex and Aerovee are amazed and a little horrified at how little hp we have available with the VW's. We do all right though.
 
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