About this Plan
Divider (MkI and MkII). RC sport stunt model. For OS Max .19 power.
Quote: "The Divider, as the name implies, divides the big airplanes from the small ones. This is a small sport-stunt ship using the miniature proportional equipment, and it is capable of doing the full stunt pattern. You have to see it fly to believe it! Dave Butler of the Rancho Cordova Model Masters flew the original Divider at the 1968 50th Anniversary Armed Forces Day celebration at Mather AFB. He really amazed the other R/C fliers with the ship. Since that time several Dividers have been built. including three by RCM's editor who wouldn't release the plan, during the past six years!
During one of the meetings of the Rancho Cordova Model Masters. I discussed small airplanes with an R/C Modeler who is well known around the California circuit. This man I truly admire for his superb flying skill, he was dead set against small airplanes for the following reasons:
1. They just don't fly well.
2. Little airplanes are harder to build: there are too many small parts.
3. Small engines arc sensitive to needle valve adjustments.
4. Small engines do not idle well.
5. Little airplanes have cramped interiors and it is difficult to install the radio equipment in the proper place.
The only good thing this fellow had to say about small size airplanes is that they are easy to transport.
In answer to this man's arguments:
1. The Divider flies exceptionally well, better than many larger airplanes I have seen at the flying sites.
2. As for building, this model is a conventional, straightforward design, using hefty-size materials.
3-4. As for little engines, and speaking of the OS Max .19, it has ample power, idles exceptionally well, and does not seem to be critical about needle valve settings.
5. Cramped interior: This model is 3 in wide on the inside and will accommodate 3 Kraft KPS-9 servos side by side. With the batteries stowed in the tank compartment, there is still plenty of room, even for the ham-handed builder.
To list several other plus factors, there is less building time; it uses less fuel, requires less space to fly; it is truly a fun airplane to fly. and as for cost, this model was built for substantially less, than its larger cousins.
As for performance. I have long felt that the proper relationship between power and wing loading is the important factor and not the size of the airplane. The Divider grosses out a little over 3 lbs, and still has enough wing loading to provide a sufficient measure of grace.
The Divider has a 41-1/2 in wing span and the wing area is about 349 sq in. The first model was built as a tail dragger, and the second has tri-gear, prop spinner, and a molded canopy for those who like the modern look. For the tricycle geared version, it may be necessary to place the battery pack aft of the forward bulkhead instead of in the tank compartment in order to keep the center of gravity within the proper limits. There is still plenty of room for this installation. Both airplanes have identical flight chanicteristics. Tail surfaces are generous and ensure excellent snap and spin maneuvers with instant recovery. Strip ailerons combined with a short span provide a fast rate of roll, if desired. However, the airplane can be through smooth five second slow rolls.
The airfoil is a semi-symmetrical section. I have nothing against the full symmetrical section except that most require jigging during the construction of the wing. This section is flat on the bottom from the main spar to the trailing edge, which permits building on a flat surface. In flight, I am unable to detect any difference in performance. either upright or inverted. Both inside and outside loops seem to he the same diameter.
Construction. The building of this airplane is simple; however, you will save time by following the procedure as outlined. Make sure you have all the necessary materials on hand prior to starting the construction. Make thin cardboard templates of the wing ribs, tail surfaces, bulkheads, etc. Trace all pans on the proper size balsa and plywood with a ball-point pen. All the necessary parts can be cut out in two or three hours..."
Hi Steve - Here is Lou Weihs' Divider from RCM magazine issue 12-74. Model # pl-581.
Direct submission to Outerzone.
Update 19/10/2016: missing article page added, thanks to Gunars.
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User commentsSome photos of my friend's Divider [more pics 004-006]. This is truly an outstanding sport flier. You don't hear much about it nowadays. I never considered building it until my friend asked for a 20 size sport plane recommendation. I had never seen one, nor even heard of anybody building it, but I thought the plan looked pretty good, so we tried it. It turns out that it is a very good design. My friend has tried the 25 FSR, 25 FP, and Enya 19 on it, and it always performs well. The more powerful engines provide a stronger takeoff, and the lighter engines provide better flight performance due to reduced weight.
Balsaworkbench - 09/02/2018
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