Another Yamaha Re-Power Highlander is flying

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Re: Another Yamaha Re-Power Highlander is flying

Postby Copro » Fri Apr 20, 2018 9:30 am

I flew all winter in Idaho. Lots of below freezing starts. No issues, I am running the RK clutch as well.

Thanks
Jody
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Re: Another Yamaha Re-Power Highlander is flying

Postby marl59 » Thu Jun 14, 2018 3:33 pm

A Yamaha powered update:
The plane is working very well. I cant report on cold starting because I hardly ever gets below freezing where I live here on the coast of N. Cal. So far no problems. I have been playing with flatter pitches on the prop and I have seen 1,800 FPM climb rates when I'm alone. :D
I have one problem so far and its significant. Its running hotter than it should. The other day at 400' elevation airport with a heavy passenger, (#225), 90 degrees Fahrenheit, my coolant temp hit 240 degrees. Way too hot!. I will be modifying the air stream to the radiator to bring the temp down as well as adding a sheet metal lip below the radiator to create negative air pressure behind the radiator. I'm sure the current shape of the lower part of the cowling is not conducive to good air flow for this setup. But I wanted to see on a hot and heavy day to see and I have my answer. I'll report my results after mods. If all else fails I will be springing for a new cowling from Just, like Steve H. is running, he's not having any cooling issues. Just got new 2" TK 1 shocks to replace my original TK 1s and should be significantly better landing dampening. I now have about 50 hours on the engine. Still super happy with the setup!
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Re: Another Yamaha Re-Power Highlander is flying

Postby danerazz » Thu Jun 14, 2018 5:31 pm

Sounds like a significant but relatively easy problem to deal with. That’s why they call it experimental!

Seriously though, I am watching with great interest, as this is my number 1 option for HL #2 (if it happens).
Dane

Paralysis by analysis
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Re: Another Yamaha Re-Power Highlander is flying

Postby gkremers » Fri Jun 15, 2018 9:11 am

I am also very interested in this engine. Please keep us all updated as you build more hours on it. If I was in the market for an engine this one would get serious attention. My Rotax 912S has been fine with no real issues other than the float fiasco a couple of years ago. The price is really ridiculous but somewhat of a captive market. I think the Yamaha would be perfect especially when I'm on floats.

Gary
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Re: Another Yamaha Re-Power Highlander is flying

Postby SheepdogRD » Fri Jun 15, 2018 9:42 pm

marl59 wrote:I will be modifying the air stream to the radiator to bring the temp down as well as adding a sheet metal lip below the radiator to create negative air pressure behind the radiator.

Where do you have the oil cooler mounted?
Richard Holtz
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Re: Another Yamaha Re-Power Highlander is flying

Postby danerazz » Sat Jun 16, 2018 6:00 pm

SheepdogRD wrote:
marl59 wrote:I will be modifying the air stream to the radiator to bring the temp down as well as adding a sheet metal lip below the radiator to create negative air pressure behind the radiator.

Where do you have the oil cooler mounted?



Should be in a big scoop on the belly aft of the gear, make it look like a p-51
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Re: Another Yamaha Re-Power Highlander is flying

Postby marl59 » Mon Jun 18, 2018 12:09 pm

That's right Dane. Then I just need the six .50 cals in the wings and I'll be good to go! Look out coyotes!

Update on the cooling, the radiator is mounted about 3" forward and at the bottom of the firewall. Similar to where Steve Henry places his on his Yamaha powered planes. I cut off the semi circular down turned lip on the stock Rotax cowling and put a panel in to fill the half round hole. This panel directs relative wind into the bottom 1/3 of the radiator which sticks below he cowling and in the air stream. I also put a down turned lip at the bottom the the radiator to create a negative pressure behind the radiator. These mods brought my cruise temp down from about 215 to 192. Next I'm going to fab some sheet metal panels to direct the airflow from the large rectangular opening below the prop, (the old radiator opening), into the radiator. I'm sure this will get my temperatures down to the 180 + range during cruise. The problem with this setup is cooling during idle when the prop is not turning because of the clutch. If I'm held for a long time on the ground waiting for take off clearance it naturally starts building up the temperature. What I normally do is either turn off the engine or idle it up fast enough to get the prop turning. The latter doesn't seem to bring the temp down very fast. If it becomes an issue I'm going to install a pilot operated cooling fan. But I don't think I'll need to do that. I enjoy this stuff, problem solving! Its so refreshing to be able to tackle this stuff on my own as opposed to my certified Bonanza.
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