We had a NW Skyraiders FUN-FLY last weekend, and both our donated trainers were put into use. Oddly, both have Enya power, tho one came from Oregon, the other from the Tacoma area. One has a .15 III and the other a .19 VI (on a Streak Trainer). It was the first time I've ever run an Enya, so I'm far from being an Enya "guru". We were flying on the asphalt ramp at Scobee Field. Grass would have been better, as it turned out.

The .19 got a broken case for it's efforts, cracked across the bypass from the top front bolt toward the "backplate" area. The muffler also took a big hit, but the clamp-on plot seems more forgiving than a really rigid setup. The .19's muffler was then fit onto the .15 III, which did not have one previously. The props we ran on both the .15 and .19 were 8.5 x 6 RevUp. I'd suggest a durable, flexible 8-4 or 8-5 would take some of the blow and help the airplane survive. A 9-4 or 9-5 for the .19. Master Airscrew, I suppose. I've seen old Tornado nylon props throw a blade on a backfire, so I wouldn't use old nylon props.

I came to a some conclusions:

First was that a side-mounted engine may not be the best plan for a basic trainer, because the muffler takes a big hit, and you do want to run a good muffler.  If you're stuck with side-mount, consider adding a 3/32" music wire hoop/skid under the muffler to help the muffler survive.   

Second,  it'd be better to use an engine that has a one-piece case with a removeable backplate. If you're just deciding on which Enya, then mount it upright if you can.

Third,  any engine to be used on a trainer should have good parts support from the manufacturer. Enya, in this country, is not the best. Fox would be pretty good, and the plain bearing .19's are nice runners in either 3 or 4 bolt backplate variety. Fox might even have a clamp-on muffler for them.

Fourth, cheap swap meet engines are perfect, if they have mufflers. If they get broken, plug in another, but save the remains for spare parts....or repairing,  if parts come your way. 

Fifth, handle ergonomics is an important factor, along with overall control ratio.

Six, a two handed handle is a good idea. See picture attached of Eddie Culver's dual instruction handle design.

Seven, use a clunk tank so you can 'short tank' without any problem, i.e., a 2 oz tank, launched half full. No uniflow, just basic stuff. The standard Hayes tank would be excellent. 

Eight, hate to say it, but a safety thong is not very practical for dual training. 

  Steve

I used a Enya 15III when I got back to the hobby and love it. Used 10% nitro 20% oil, Enya 3 Plug, 6.5~6.7mm venturi  and it worked best with a TopFlite 9x4 prop. I used 50' lines with it.

Most people underestimate the power of Enya engines and tend to use the wrong prop with it. The 8x6 went to fast and did not have the same good speed control as the 9x4. But prop will depend on you Density Altitude, so try a few props to see which ones works best.

Although this is a very old engine Enya still has parts that are easy to get from them directly or from Randy Smith. No other Engine Co. keeps parts in stock as long as Enya has been doing. Just recently they start running out of parts for engines that were built back in the 60s.

Hope you will enjoy the torque and reliability of these engines.

Martin

       I used the Enya III for two years and had nothing but trouble with it. The Enya instructions say to use 20% oil content. I was using 25% and it was giving me problems until I switched to the 20%. This was Sig Champion fuel I was using. I discovered what I believe to be the problem. For starters, the Enya III has a smaller cylinder head than the Enya IV. I believe they enlarged the head for cooling. In addition, the Enya IV has no casting obstructions within the casting. I firmly believe the III version retains too much heat therefore midway through the flight wants to overheat , runaway, then start sagging. I also learned that the Spraybar assembly for the OS La.15 is a better choice due to its smaller diameter. The stock muffler will cause nothing but headaches due to the opening being too small. This engine worked beautifully on a R/C bird my father built but the engine isn't running flat out on the R/C plane. I found that a Randy Smith tongue muffler for the FP .40 fits the Enya close enough to use. I was able to use the stock muffler strap to retain the tongue. I had extreme varnishing problems using the 25% due to the engine overheating and sagging towards the end of the flight. When I switched to the 20% this problem wasn't as bad. The engine would start very easily though until it got hot . Restarts were almost impossible until it cooled. I used a 7x6 prop for my set up which allowed the engine to run at a more comfortable state and kept the overheating down as well. These engines require extensive break in. Unfortunatley when mine did break in it was worn out. These problems were mainly due to the extreme overheating I subjected the engine too when it was running away and sagging using the stock muffler. I tried several different tanks, uniflow, muffler pressure, etc. I couldn't feed the Enya III enough fuel to keep it cool. The needle would have to be set so rich on take off that it would barely get off the ground then 1/2 way through the flight it was off to the races. I've experienced this with 2 Enya III's so far. I noted the differences with the IV version but have yet to test my theory about it. Ken