Norvel Engines / Acromaster

Just a quick question. I have a SIG Acromaster that I have been holding off building until I could find a good powerplant for it. The Acromaster is listed as a .15 - .19 plane and I was wondering if the Norvel .061 c/l or the Norvel .074 R/C engines would pull this plane and not require onces of tail weight to balance? I would think that the .061 would be marginal but Norvel lists the .074 as being equal to a .10. I take the .15-.19 rating of the Acromaster as being for the older engines with the new smaller powerplants as being capable of pulling this plane.

What say ye?

I'd go for the .074, least I'm going to on my next one.

Finch,

What is wrong with a Fox .15x slant plug? That is what the plane was actually designed to use and by all accounts I have seen that is a very good combination. The Fox .15x is almost always available on Ebay at reasonable prices. I have purchased 4 of them over the last two years and have one on the Sig Acromaster I just refinished. I haven't flown it yet though. Hope to do so before winter and the new building season sets in. Clean, did you fly the Acromaster you have with the Fox .15x and if so, how did it fly?..................T.Durrill

The 15 would be fine, cept I built one with the little steelfin 15 on the nose and its STILL nose heavy. The Norvel is a little less weight, probably more power.

Last summer I put a Norvel .049 engine with a 6x3 prop on my Sterling Ringmaster just to see what it would do. The Ringmaster has a 42" wing span. I expected the Ringmaster to fly sorta like a PLASTIC airplane that I had once with a .049 cox engine. Once the plastic thing got up some speed it flew by centrifical force. It was impossible to do anything expect go in circles.

The Ringmaster was a little slow on the take off with the tiny engine but once it got up some speed it flew. I could do a wing over. There did not seem to be much speed lost as long as I kept the turns very large. I could do "ONE" inside loop as long as it was a very large loop. The .049 engine is way too small for the Ringmaster and probably too small for the Akromaster too. Norvel engines are hot rod engines. A Norvel .15 would be more than enough engine for the Akromaster and would probably be a load of fun. I think your probably right the .15/.19 rating is probably for the OLD engines. I am guessing a Norvel engine about half the size of the Norvel .15 would work. Norvel has a .074 size engine give it a try.

By the way, the .061 CL venturi can be installed in the BigMig .074.

After the change to the .061 venturi on the .074,are there any other changes that would need to be made as well such as fuel,props etc???

Fly Right & Tight
Mathew L. Suddath
AMA 818198

I have not run the .074 since making the switch. Comparing the carb from the .074 to my .061 and .049 BigMigs, it appears they use the same parts for all three carbs. I have not compared PN's.
I have a Tornado 6x3 on the .074 for break-in and expect to try a 6x4, 7x3, and 7x4 later.
Switching the .074 to venture feed should be similar to switching an .049 or .061 from throttle to venturi.

As far as the Akromaster, I use a TT .10 on my latest and a Fox .15X on my old one. Neither built particularly light.

If you go with the Norvel get the .074. I have no experience with them, but understand that they make great power for their size. My buddy has an Akromaster with an O.S. 15 FP on it - too much power, a modern .10 would be better. If the Norvel .074 is as powerful as they say it should be a good match.

About 8 years ago I had an Acromaster powered with a Tee Dee .09. It had plenty of power at our mile high (Denver) elevation. My next one will be with a Norvel .061 or .074. It will be built as lightweight as I can build it!

I typically don't do the bay for any thing. I was really looking for a current production engine that could be used for the Acromaster. My first choice was going to be the OS .10 but then the talk of the Norvels recently got me looking at them. I would think that the .074 would be a little lighter than the OS .10 and might possibly be a better match for the plane. If this works out I wanted to try out some full fuse builds for these little engines using the Acromaster numbers or stretched a little like a Fancher Twister.

With the .061 venturi on the .074, how does that affect performance and what sized props would be applicable.

Thanks,

I have a Norvel .049, .061 and .15. You can buy the engines with or without a plastic fuel tank attached to the engine. The .049 fuel tank will hold enough fuel for a 3 minute flight. The engine with the fuel tank costs more than the one without the fuel tank. I noticed the Norvel .049 engine with NO fuel tank was $32.00 at the hobby shop last summer not sure if the price has gone up. I am not sure if the .074 engine has a fuel tank option or not. The new engines are usually a few dollars cheaper on ebay. I bought the .061 without the plastic fuel tank I wanted to pick my own size fuel tank for an 8 minute flight.

What amazes me...Norvel rates their .074 at 0.38 HP at 22K!

I've had slightly below average McCoy Redhead .35s in that HP range, albeit at less than half that rpm.

We flew an .061 powered Skybaby just for fun a few summers back. The little Norvel was a real sweetheart when you got the needle right...it "came on" just perfectly in the air, running mild muffler pressure. A real gas hog, though. But, if you want the performance...

j.pelham Yes we have a acromaster W/ a norvel 15 were going to check out after Jeanne is out of here looking forward to see how it flies? We had a old Fox 15 didn,t seem to have enough power.

Note that the Akromaster is about the same size as a lot of 1/2-A Combat models these days. It is heavier, though. If built light, I'm sure a Bigmig .061 could haul it around.

I've had a lot of fun with this plane and the OS10 FP, with either the R/C carb, or the *correct* C/L venturi/NVA. Goes like a dream.
Get the wrong NVA though and it's a total pig. If you're interested I can dig out the details.

I cut the nose down on my ackromaster until the tank started riding over the LE. I was trying to balance an old Max 15. Now it has a Max 10FSR w/muff and verry thick steel liner. Bet it weighs more than an old fox 15, but not that much. Or are Ackromasters supposed to balance on the LE? Mine feels like a rock on a string that way. Don

Don,
The big difference is probably the muffler. When the Acromaster was designed, most did not need or use mufflers.