Welcome to the start of our IMAC FAQ page. More information will be added shortly, but for now, we have an excellent essay by Tom Fawcett. rcfaq

The quest for the ideal first IMAC plane in ARF form...

By Tom Fawcett

Recently I have mounted a search for the ideal entry level IMAC plane. What I'm looking for is a plane that will fly up to the sportsman pattern and be competitive, will travel in one piece in the back of a short-bed pickup, is economical to build and operate, is an ARF so anybody can buy it and fly it.

Ideally it will run on a small gas engine such as a Brison 2.4 or a BME 2.7. Second choice is a 1.20 size 2 stroke glow engine.

My search started with the Dave Patrick Ultimate. That was not a great success. I put a Brison 2.4 on it, with several other mods to make it durable and balance without ballast. Problem was by the time I was done it weighed over 14 lbs. The biggest problem was the cowl, which was much too small to accommodate the muffler. I ended up with a Macs header and a KS can muffler mounted along side the fuse. It was quiet and powerful, but kind of missed the mark on its aerobatic precision. By the time I finished it I had about $1,500 invested without resorting to expensive digital servos.

I have been experimenting with some of the more obscure ARFs that are available. Some may remember about a month ago my report on the Goldberg Decathlon with a Thunder Tiger 1.20. I flies pretty well but it is not as easy to fly an IMAC sequence as, say, a Goldberg Extra. That plane ended up costing under $1,000 including two JR digital servos. Weight was about 11 lbs., with an 80" wingspan this plane has potential.

My latest experiment is with the Lanier 1.20 size Extra 300L. It's a nice ARF, finished in blue and red Ultra Coat. It has a 77 3/4" wingspan. The fuselage is somewhat narrower than a true scale model and looks much sleeker than other Extras. I haven't measured it to see if it's within the 10% scale rules.

Upon first examination the fuselage looked like a brick, lots of wood. It is stronger than any of the 1.20 size planes I have had. I decided it could stand up to a BME 2.7. The problem again is the cowl, but not as bad as the DPM Ultimate. Everything fit inside except the carb inlet which pokes out of the cowl just a touch. It doesn't hurt anything but it looks a little cobby.

The way the ARF comes it's set up for tail mounted elevator servos. I built it almost 100% stock. Mods included stronger landing gear (TNT) and triangle stock at the firewall glue joint. That's it.

The plane, to my amazement, came out at 13 1/2 lbs, ready to fly. This with 1500mah NiCD on RX and ignition, 6 servos, BME 2.7 with J&A inverted pitts muffler, etc. It has sufficient wing area that it just floats on landing, very much like my Radiocraft Extra.

This ARF is not expensive, $320 at Tower Hobbies. The engine was the most expensive part, but I think I have about $1,200 in the plane all together. Not too bad for a plane that looks like it can compete, and the engine will last through many other airplanes I'm sure. The savings from using gasoline (I estimate it saves about $1 per flight in fuel, annoyance and paper towels) will more than compensate for the initial engine cost. Just the fact that I don't need to go to the hobby shop to buy fuel is worth the extra cost.

My first flights were in 15-20 mph wind, so it's a little tough to say how this new plane flies, but it felt very similar to my Radiocraft. It has flat tail surfaces and I did not set it up as a 3d plane, so I can't compare its performance there, but the handful of maneuvers I did do in the wind felt like it will be ok.

One little problem on first flight. I set up the ailerons similar to my Radiocraft Extra in terms of throw angles. On low rates it was so fast in roll I thought I might lose it at first. Got it back successfully and cut the travel back to half what it was, and now it flies great. I guess the ailerons on this plane are more effective than what I had expected.

Anyway, this plane has a lot of potential. It will be tail heavy with almost any glow motor except perhaps a big Moki. It's not as sophisticated as some other planes (flat tail, etc.) but it's simple, light, strong ( there's a combination you don't see often) and suitable for a small gas engine.

More later.

Tom Fawcett

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