View Full Version : Lycoming Powered Dominator?
02-17-2011, 12:49 PM
Hey all! I'm getting the building bug again and was wondering if anyone has ever built a 2 place Dominator with a certified aircraft engine. I've been constantly impressed by the quality of Ernie's machines and think that the addition of a Lycoming O-320 would make a great cruising/training machine. My main concerns are the additional weight of a Lycoming as compared to a Rotax or Yamaha and whether or not the square channel construction of the Dom will be able to handle the additional torque. Obviously I'll have to fabricate a custom Dynafocal type engine mount and maybe beef up the main gear... Any thoughts??
02-17-2011, 01:25 PM
The torque on the airframe is determined by the torque on the prop, (not the torque applied by the crank to the input of a reduction drive bolted to the engine,) and a 160-HP O-320 would be in the same ballpark as the 150-HP Yamaha Ernie's using if the prop RPM are similar.
The weight's not as much more as it looks. I believe an O-320 is about 250 lb.
I've seen pre-fab dynafocal mounts for common aircraft engines available as subassemblies, but if I recall they're made of 4130 steel.
02-17-2011, 01:34 PM
Or you could put a 912S on it and save 110lbs compared to the 0-320, and run it on mogas
02-17-2011, 02:56 PM
Paddy, at least over here, you can run an O-320 on mogas. In an experimental, you don't even need any extra paperwork.
I was at Vans Aircraft a couple years ago to do a story on the RV-12 LSA, and they were just bringing it back from a trade show about two hours north of the factory. They flew the RV-12 (Rotax 912) and an RV-9 (O-320) in formation, matching speed all the way back. Fuel burn was nearly identical.
Cooling an O-320 on a pusher could be a challenge, but Vance's Predator makes it work.
02-17-2011, 06:12 PM
Your idea sounds interesting. There's history in the method of mounting Lycoming engines to aluminum box tubing structures with Hollmann Sportsters, Marchetti Avengers, and a Parson Trainer. In fact, back in April 2010, Steve Craft of Hebron KY had completed a Lycoming powered Parsons Trainer and was getting ready to fly it then.
I just looked at Steve's website to see if there's any updates, however it doesn't appear there has been any entered.
02-18-2011, 05:17 AM
I spoke to Ernie a few years back, Mike, "MissFit", had a 320 and we were contemplating installing it on a Dom. He doesn't recommend it.
02-18-2011, 06:12 AM
Is the throttle´s hand the only dampener/regulator for prop torque or is it possible to make it mechanical?
02-18-2011, 07:59 AM
Do you recall if Ernie mentioned any specifics regarding why he didn't recommend installing a 320 on a Dom? I e-mailed RFD 2 weeks ago with a similar inquiry but as of yet haven't gotten a response.
02-18-2011, 10:31 AM
Might wanna look closely at a Twinstarr too... They use an A/C engine and could give you some mounting ideas if you go that road. I cannot see why an A/C engine would not be a good idea especially since the Yamaha he is using now is nearly the same in all aspects of HP and weight... Give him a call and talk to him... he will usually answer your questions very bluntly yet informatively.
02-18-2011, 01:28 PM
Hi Jon, He said the torque impulses from the large displacement engines were difficult to manage. It wasn't so much the overall torque. He also mentioned cooling as being a perennial problem with a pusher on a low speed aircraft.
02-19-2011, 09:54 AM
The extra weight is a compromise, like many we must make.
But you would have one heck of a cross-country machine!
I think maybe the mounting problem may come from the fact that on a Dominator all of the engine focal point eventually comes down to the mast structure, where as on the Twinstarr and the Predator there is somewhat of a airframe for the mount to attach to which takes the engine pulses much better.
02-20-2011, 07:56 AM
Jon....Si Smith has a 150 hp Lyc in the Marchetti....I can let you in the hanger some weekend to look it over if you like.....
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