Here is a model airplane design that should prove to be very interesting to try out in order to determine whether its designer, Roy Clough, Jr., is correct about his theory of the aerodynamics of the curve wing center section. The pusher configuration with the reward-facing engine between twin tail booms probably kept a lot of people from trying it back in the 1950s when small electric starters were not commercially available for .049 engines. Today, the issue can be mitigated entirely simply by converting the power system to electric. Mr. Clough believes the rear engine configuration pulling air across the curved airfoil section will always provide some amount of lift regardless of the angle of attack of the rest of the wing, and that allows shorter takeoffs, lower stall speeds, and a lift boost then the engine switches into a leaner operation as the nose goes up. It is definitely an attention-getter due to its odd looks.
Channel Winger C/L Pusher
By Roy L. Clough, Jr.
We've been mighty slow getting this oft-requested model to you, but it's worth the wait!
The main idea behind the channel wing configuration is that if air can be kept flowing over a wing section lift will be produced regardless of the forward speed of that wing through the air.
So the Custer Channel uses a semicircular airfoil section with the propeller mounted just inside the trailing edge to insure a strong draft through the channel which is independent of forward motion. Thus there is a section of the wing which can never stall-as long as the motor keeps running. This, Custer reasoned, should allow very steep take-off and landing patterns and greatly reduce ground run.
There seems to be little doubt, on the basis of our tests, that the channel reduces take-off run and does indeed produce some static lift. It will also operate well beyond normal stalling angles without paying off. The increase in static lift in flight - a condition which occurs when the model is put up in a four-cycle and suddenly leans out - is noticeable as a sudden ballooning, similar to that which takes place when a dummy bomb is dropped from a stunt job. The model not only scoots ahead faster, it also rises up a foot or two. This does not make it difficult to control; the effect may be explained by noting that, all things being equal, it takes more up-elevator to fly a heavy ship than a light one. When the motor leans out in the channel job it suddenly gets quite a bit "lighter."
Don't let the U-shaped wing scare you. It is quite easy. The first item needed is a standard gallon size fruit juice can (try a hotel or restaurant) to serve as the mold for the laminated spars. Wrap a layer of wax paper around the can, soak the 1/32" spar blanks in warm water for a few minutes and layer up the spars using Weldwood Plastic resin glue or something similar. Do not use non-water-soluble model cements. When the final lamination is in place pull the spar together tightly with a band of cellulose tape around it and the can. Allow the spars to dry thoroughly, at least overnight, in a warm place.
Once the spars are set the wing construction is the same as for any three-spar wing, but easier because the semi-circular spars practically align themselves. The two outer panels are built separately. Cover the inside of the channel, slide the plywood anchor beam in place and attach the outer panels. Now we cover the under side, put in the tail booms, fins and tail plane and bolt the landing gear in place. Cover the remaining area of the wings' upper surfaces, inserting about 3/4 ounce tip weight in the leading edge of the outboard wing.
The nacelle-type fuselage is next. Cut the keel from 1/8" sheet and the necessary bulkheads. Note that the engine bulkhead is plywood; there is a method to be followed here because of the Thermal Hopper's mounting system. First, cement the keel, with its attached balsa bulkheads to the anchor beam. Next fit the motor carefully to the plywood bulkhead, cement the mounting nuts liberally in place. Now remove the engine and stick the bulkhead to the keel, bracing it as shown with 1/8" x 1/4" strips. Use plenty of cement on this assembly and let it dry thoroughly before proceeding. Replace the motor and put in the tank. Note on the plan the style we used, adapted from a standard wedge. A little trimming and fitting may be necessary here and the tank is held in place with bits of scrap cemented to box it in. Now cover the nacelle with either 1/32" sheet balsa or construction paper. The engine will vent through the hole where the needle valve pokes out. Carve a nose block as indicated and ballast it so the CG lies somewhere between the front wire and the leading edge of the wing.
Not much ballast is required because of the length of the nose, but don't slight it! A Berkeley bubble canopy, 5" long completes the deal which may be doped to your favorite color scheme. The control system uses a T control plate similar to and interchangeable with the one used in the "Firebaby." The line guide is simply a bit of twisted soft iron wire.
You will be able to do a lot of low speed stuff with the model not to be expected from a conventional type. Starting the motor may seem difficult at first, but this is merely acquiring the knack of bouncing the prop back against compression with the ball of the thumb so that it kicks out running the proper way.
Channel Winger Plans
Full-size plans for building the Channel Winger are part of Group Plan #754A, Hobby Helpers, 770 Hunts Point Ave., New York 59, N. Y. (50c)
The AMA Plans Service offers a full-size
version of many of the plans show here at a very reasonable cost. They will scale the plans any size for you. It is always
best to buy printed plans because my scanner versions often have distortions that can cause parts to fit poorly. Purchasing
plans also help to support the operation of the Academy of Model
Aeronautics - the #1 advocate for model aviation throughout the world. If the AMA no longer has this plan on file, I
will be glad to send you my higher resolution version.
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Posted October 11, 2014