Buttercup - Radio control sport model, for Cox TD power and micro RC gear.
Quote: "This .020-size cutie got its name from the yellow covering and its basic design from phone conversation doodling. Author flies his with two channels (rudder and elevator), but the design is suitable for a rudder-only pulse system on up to three channels with throttle control. With an .020 to .035 engine and micro radio system, it's a very practical sport and fun airplane. Buttercup by Fred Reese.
I have always liked little airplanes. Actually, I like all airplanes, but I prefer to build small ones. I especially like simple little airplanes so that, once I get the idea, I can get into the air quickly. I also like a change of pace. I will spend months on a scale project, then turn around and build something like the Buttercup in a few days.
This particular small, simple model is actually a caricature of an airplane that I doodled while on the phone. I thought it was kind of cute, so I built it. When it came time to cover the model, I chose yellow, as I had a lot of yellow Super MonoKote. I like yellow, so I named it Buttercup.
In addition to being very simple and small, Buttercup really performs well. Especially wnen pushing limits, sometimes simple things are best. Buttercup is not the smallest RC that is possilaie but it is a practical small airplane that does not require any special techniques, and it uses all stock components. It is desiped to use the Ace (or other) micro-sized radios or the Ace micro servos and your receiver along with a 100 mAh battery pack. Two different-shaped 100 mAh battery packs are available from Ace RC, and either on of these will fit. There is room enough for most any receiver.
Buttercup was three years old when this was written, and it was still going strong, I have taken it traveling on vacations. I have flown it everywhere with what seems like reckless abandon, and it still survives.
My goal for the weight of Buttercup was 10 oz, ready to fly. With the wheel pants and a few repairs, it now weighs 10-1/2 oz.
This airplane is not a docile 'putt-putter.' With TD .020 engine, it really zips along and will keep up your interest. At 6,200 ft elevation, where I fly, Buttercup will easily loop and roll from level flight.
The rudder needs to be tall to offset the large fuselage side area up front. In fact, I added 1/2 in to the top of the rudder after the third flight to smooth out the rudder response. Buttercup climbs continuously at neutral trim, but with the relatively short engine run, I feel more comfortable when the airplane naturally regains lost altitude from maneuvers. A little down-trim will level it right out.
Since Buttercup has a built-in climb, it is ideal for the Ace Pulse rudder-only system, I did not show the installation on the plan, but if you go this route, you should make the stabilizer and elevator in one piece, and cut a iittie hole for the oscillating wire to pass up through the elevator to a yoke on the rudder. I have very fond memories of a little Piper Cub of this size that I built about 15 years ago - using the Ace Pulse system. if you fly closer to sea level than I do, you might consider the little G-Mark .03 throttleable engine from Cannon and three micro servos.,
Construction I used Zap CA+ for all coonstruction, except for some 5-min epoxy to join the wing panels and to glue on the wheel pants.
Fuselage. Cut out the sides, and glue on the nose doubler, F-1, the 1/8 x 1/2 strips behind the firewall, and the landing gear braces, F-6 and F-7. Bind the 1/16 wire landing gear to F-3 with heavy thread. Glue Bulk-heads F-3 and F-4 between the fuselage sides. Glue the sides togehar at the tail.
Mount the engine to the flrewall, F-2, using 2-56 x 1/2 in bolts and blind nuts. Glue F-2 into the fuselage. Glue the wing mount F-5 in place, and add the 1/8 balsa top front sheeting. Glue on all of the top and bottom 1/16 sheeting with the gain crosswise..."
Quote: "Hi Steve, This is Buttercup a 27in span rudder and elevator model designed by Fred Reese for a .020 engine. To me it looks like the comic sidekick of Fred's Cloud Kitten. The buttercup plan appeared in Model Aviation magazine June 1985. Unfortunately I could only get a really bad quality (but useable) copy of this little cutie's plan but by putting it on Outerzone perhaps we can attract interest and a better quality scan, a redraw and/or the original article might be submitted."
Direct submission to Outerzone.
Update 19/08/2014: Added an excellent supplement modern CAD re-drawn version of this plan, in PDFvector format, thanks to hogal.
Update 31/08/2014: Replaced this plan (the bitmap plan, that is) with a clearer copy at 600dpi, thanks to rchopper56.
PDFvector version of the plan.
Article pages, thanks to hogal.
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