The Electric-Powered Sport Aerobatic Airplane

That is Also a Basic Trainer

How does that saying go? What is old is new again? That is definitely so in the case of the RCM Funster. Dick Tichenor originally designed the Funster in 1984 by taking a Telemaster 40 wing, adding landing gear to it and then designing his own fuselage to match it. The result was basically a tricycle gear, low wing, Telemaster 40. It was a very popular kit as a glow-powered airplane. The plans were first published in Radio Control Magazine, the “RCM” in the airplane’s name. Sadly, RCM no longer exists but many of its published designs live on as part of its legacy.

Now, this fine sport/trainer design has been revived by Hobby-Lobby International as an electric-powered ARF. The RCM Funster ARF is the companion to the Hobby Lobby electric-powered Telemaster ARF, just a bit bigger in the fuselage. It’s a very complete package, needing only your radio, a motor, battery and electronic speed controller to complete assembly and have it ready to fly.

The RCM Funster is easy to put together, but there are some things missing from the instructions that a novice modeler could really use some explanation about. This article should help to fill in those gaps, ease things along and get your Funster in the air. It will be worth the effort, because this is a nice flying airplane!

Photo 1

When you first glance at the picture on the box cover, the thought comes to mind “Hey, something is missing!” The lack of a glow engine’s cylinder head in the picture is conspicuous. But rest assured that there is a power plant hiding in there. It goes to show that the original Funster design has been preserved to the extent that it would be possible to fit a glow conversion if you have the know-how to replace the motor box with an engine mount that could withstand the vibrational stress from a glow engine.

In fact, this kit, as delivered, can be built as a glow-powered airplane. However, now that we’re in the age of electric-powered airplanes, why go to all that trouble when you could be flying electric in a day or two after receiving the box?

The photos above show a well packaged kit. The two wing halves come stacked over the vertical fin, rudder, and horizontal stabilizer. A separate corrugated cover protects the fuselage, canopy and bags of hardware. Everything is neatly bagged and organized.

Assembling the Fuselage

Here are the pre-hinged stabilizer and elevators. For that matter, all of the control surfaces are pre-hinged in the same way, with CAA type hinges, ready to be glued permanently in place with thin CAA. Note the accurately pre-cut slot in the center of the stabilizer, which forms the mounting point for the vertical fin.

The only thing that will stop you from having the Funster in the air in the next 1 or 2 days is if you spend too much time admiring it and not enough time putting it together! Getting down to business, it’s time to break out the thin CAA glue and bond the top two rudder hinges to the vertical fin. The bottom rudder hinge does NOT get glued at all until after the entire tail assembly is attached to the model in a later step.

If you’ve never used CAA hinges before, it’s very easy to do but also easy to make the mistake of not using enough glue. For detailed directions about installing these wonder hinges, see the Sport Aviator Flight Tech article, “Installing Mylar® Hinges”. Normally you hear about not overdoing it with glue and it’s still true here, but in the case of CAA hinges, you must be sure to use enough glue on both sides of the hinge to insure that it wicks all the way inside to bond firmly with the balsawood hinge slot.

Make sure that the rudder is held closely to the fin while bending it over enough to expose a small hinge line gap to the let 3 drops of CA fall onto the CA hinge. You follow one drop right after the other, as soon as you see it start to wick inside. This just takes a few seconds. Do both hinges on the one side, then immediately flip it over and repeat the procedure on the other side. With CAA hinges, you must complete gluing both sides of the hinge in one step. If you allow the glue to harden on one side, it will destroy the properties of the CAA hinge material that allows the glue to wick inside so effectively, and the gluing operation on the other side will not form a good bond. In fact, it will tend to just build up and drip away from the hinge if you make this mistake.

Set the assembly aside for about 10 minutes or so, and then move the rudder back and forth a few times to allow it to move freely after it is installed on the airplane. If you use 3 drops of CAA, you normally won’t have any excess glue drip on anything, but if you do get some on the finish, don’t worry about it too much. CAA remover will take it off. Just be sure to avoid getting any remover in the hinge slot and everything will be fine.

Attach the one-piece elevator to the horizontal stabilizer, following the same CAA hinge gluing procedures as on the rudder. It’s now time to join the rudder/ vertical fin assembly to the horizontal stabilizer. One final note about CAA hinging though: When the “hinge count” starts to get up there, you may want to do smaller groups of hinges at a time so that you have enough time to wet both sides of the hinge before the adhesive sets. In other words, it may be best to glue top & bottom of the left side, and then move to top and bottom of the other side. This will assure that the CA will wick properly, as described. Just be sure to keep the parts close to each other and in alignment throughout the procedure.

Now, on to gluing the vertical fin to the horizontal stabilizer! It is very important to have things squarely aligned; otherwise you will have trim problems for the life of the airplane. Using a pair of triangles as pictured above is an easy way to assure proper alignment. After aligning, simply wick in CAA along the joint; avoiding the area near where the triangles are set. Use a decent amount of glue here (not excessive). However, keep in mind that thin CAA will not fill any gaps. A good bond with thin CAA requires that the parts mate snugly and that enough adhesive is used to wick well into the joint. Basically, you slowly draw a line with a steady flow of CAA along the joint. It should take maybe 5 seconds per side of “drawing a line” to get enough glue in there with a steady flow coming out.

After allowing it to set a few minutes, remove the triangles and dab a little more thin CAA on each side.

Every model airplane I have ever built over nearly 40 years has provided its own “journey of discovery”, and the RCM Funster is no exception. Actually, I never really expected to find that the covering would be pre-trimmed in the area where the bottom of the horizontal stabilizer gets glued to the fuselage, but I was thinking that some explanation of how to properly remove it would be helpful. In fact, the instructions didn’t even mention that you have to do this at all. It’s obvious to an experienced modeler, but perhaps not obvious to all. You should not try to cut the covering directly with a knife, because it will almost certainly damage the underlying wood by cutting it across the grain and weaken the structure.

The next series of photos show one method of removing the section of covering without ruining the structural integrity of the stabilizer. First, please take notice in the photo 8 that the area to be removed has already been marked with a felt pen. You must first align the tail assembly on the model exactly as it will be when permanently installed. Then make the markings using the fuselage sides at the saddle to guide the felt tip pen.

Using a sharp, new single sided razor blade, carefully slice the covering in between the lines. Watch those fingertips! You may need them later. Also, you must not press the blade into the wood below! Hold the blade as nearly horizontal as possible and using just the corner of the blade, slice into the covering only. You just can’t be very accurate with the line when doing this, which is why you just strive to stay between the lines for now. Do this from the trailing edge to the leading edge.

Next, slide something like a piece of thin cardboard or plastic under the covering, just far enough to assure that when you cut along the line, the wood underneath will be protected. I used one of those “Hi! My Name Is…” badges from some trade show I once attended. The choice of suitable protection material is yours, but this seemed very appropriate to me. Notice how this raises up the covering, but the part that remains after the cut is completed can be ironed back in place after the center covering has been safely removed.