Swelta (oz8081)

About this Plan

Swelta. Radio control sport model.

Quote: "Winner of the 1967 Toledo Conference Best Original Design Tro-phy, the Swelta will be a sure-fire hit at the local flying field. By Dr Harry Hodel. Photographs by Reynolds.

SOONER or later, every long-term modeler will try his hand at designing an airplane. We all do a little of this by making minor modifications of pre-existing designs. This has resulted in the present trend of look-alikes. There comes a time however, when each of us would like a unique original design which should at least look pretty - and hopefully be able to fly well. The resulting appearance will no doubt be a culmination of his past experience and his concept of what his 'dream' should look like.

Whether or not it flies well, is not of prime importance because all his other planes are able to do just that. But imagine his thrill, if it does perform well after he gets enough courage to try it out!

This is how my 'Swelta' was conceived. To begin with, this design was never intended to be just another class III contest machine because we already have so many excellent designs to choose from. What I desired was a unique plane, unlike any other, yet pleasing to the eye. I liked the appearance of Delta wings but they lacked beauty without a fuselage. They also lacked some of the favorable characteristics of the conventional designs. By the addition of a fuselage, the favorable characteristics of both types could be combined. Previously, whenever this was done, the motor was always placed aft with a pusher prop, to solve the placement of the CG. This detracted from the appearance and also required special structural reinforcements.

I feel I have achieved my goal by solving these problems. So what is unique about the Swelta? Appearance for one. It almost looks like a navy jet fighter. The way it flies is another. I have never had a model stir so much interest in spectators and modelers alike. Rarely have I seen a model hold a crowd so spellbound. What more could I ask for? It handles as easily as most class III planes, yet is able to fly much slower because of the reduced stalling speed. The Delta wing permits the model to be easily landed in a nose-high attitude without any tendency to fall off. This adds realism. Maneuvers are smooth and control re-sponse is positive at all speed ranges. Rolls are very axial and breathtaking to behold! Because of this feature, a low pass ending in a victory roll is one of the Swelta's most spectacular maneuvers.

The addition of a tail section produced another feature namely the ability to do true tail spins. I have yet to see a Delta capable of this. Inverted stability is unexcelled since there is virtually no difference in control response. Rev up that engine and it streaks across the sky! This is fun!

Where did the name come from? SWEpt back deLTA = SWELTA. That is just what it is. There are several interesting design features incorporated into this plane. The wing differs markedly from most delta wings, which have one thing in common. They employ a double reflexed airfoil, which imparts a positive pitching moment, thereby creating lift. This was not necessary for the Swelta because it has a tail section. The wing, therefore, is fully symmetrical! Although it is almost 4 in thick, the airfoil is still only 12%. Even though I'm an avid barn-door enthusiast, I felt that because of the reduced wing span I would need all the aileron action I could get. I therefore used full-span ailerons. They were so effective that their size had to be reduced.

One major problem was the fuselage length, since this is mainly dictated by the chord section at the center of the wing, plus eight inches of length which are required in front for the engine, tank and nosewheel. Adding this to the tail moment, which I established by preference, results in a long body. My final plans are smaller than the originals. When you have a heavy engine and a full 12 oz tank a long distance ahead of the CG there must be some compensation in weight distribution to keep the balance point where it is desired. This was accomplished by placing the servos just in front of the stabilizer..."

Note this is a low resolution plan, at 100dpi in greyscale.

Update 06/10/2016: article pages, text & pics added, thanks to RFJ.

Supplementary file notes

Article pages, text & pics.

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