Thermal Thumber (oz2959)
About this Plan
Thermal Thumber. Free flight power model for Cox .02 Pee Wee power.
Quote: "For sport flying, this .02 powered free flight, splendid preparation for contest ships. Simple, quite stable. Thermal Thumber, by Gabe Bedish.
Were Aristotle here to view free-flight, he would probably exclaim about seeing something of a bird. Progress!
The model presented here seems almost predisposed to be away with the slightest thermal activity. Bearing this in mind, the title 'Thermal Thumber' was contrived.
Designed for sport-flying, and, as a model to break into high performance free-flight with; the purpose of the development of Thermal Thumber is to put together a model for beginners from which stable, high performance ean be found without the modeler having more than basic knowledge of techniques of flight adjustment. The model can be constructed in a day, yet is sturdy enough to last through any trials which may occur in learning the ways of free-flight.
The shape of wing and tail surfaces on this Cox .02 Pee Wee powered Lilliput is for gaining better directional stability without reducing fine gliding characteristics. Sweepback increases directional stability and forward-placed tips help overcome stalling tendencies before they become severe.
A pylon removes the wing from much of the turbulence of the propeller stream to allow it to do work in relatively undisturbed air flow. Fuselage design provides for smooth contours; near maximum rigidity; and ease of construction.
Fuselage: A three-piece keel is com-posed of vertical and horizontal mem-bers. Trace and cut patterns for the horizontal and vertical keel members from tracing or onion-skin paper. Then, trace them on hard sheet balsa and cut out keel pieces. Cut out pylon piece and cement into place. With pin holes for guides, cement horizontal keel parts to either side of vertical keel. Attach wing mount base and retaining pins. Drill holes for pins.
Form landing gear strut. Notch the front of vertical keel to take strut. Drill hole for upper strut end. Cement strut into place. Cut hole for flight timer in vertical keel. Attach pull-cord to timer and set for ten-second run. This should allow for a 20-second engine run as fuel is emptied from tubing connection from timer to engine. Cement timer into place and attach lengths of plastic tubing fuel line. Plug exposed ends to prevent foreign matter from getting inside. Attach pull-cord guide.
Carve or rasp fairing blocks to shape from medium-soft balsa and cement them to keel pieces. Firewall is put together with hard sheet balsa sand-wiched between plywood. Drill holes for engine mounting and insert mount-ing bolts through them. Turn nuts and lock washers into a tightened position..."
Quote: "Here is Gabe Bedish's Thermal Thumber from Model Airplane News issue 02-60. I've included all pages as they are informative on how to construct the model and depict the unique graphic for the pylon."
Direct submission to Outerzone.
Update 08/07/2019: Added article, thanks to theshadow.
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