About this Plan
Rubberdub. Free flight rubber model, a parasol sportster.
Quote: "Rubberdub, by Brian Lewis.
Representative of a class of aircraft quite popular in the 1930s 'Rubberdub' makes a change from the usual run of high wing sport models and is quite an attractive proposition for beginners or expert. Its semi-scale lines with simple parasol wing mount and use of a standard 10-inch Obeche commercial prop make it ideal for a one design club contest where everybody is required to build the same model and with all club members working on the same basis, a lot can be learned from the different approaches to flying trim. Very often in contests of this kind the beginner gets his chance of ousting the so-called expert, so why not try it this winter in your club?
Rubberdub is a small-field flier with average duration hovering around the 90-second mark to give a maximum of fun per flying hour.
Commence by building two basic fuselage side frames flat on the plan, one over the other. When dry join together, using Former F3, and pulling together at tail then inserting Formers F2, 4 and 5. Insert spacers at nose and add F1. Fit 3/32 stringers and add 3/32 sq spacers on bottom and the decking. Sew 18 g cabane struts in place. Bind undercarriage and tailskid where needed and apply cement liberally. Add sheeting and gussets. Bind 18 swg wing mounts in place with fuse wire and solder. Note that the strut fairings are not added until after covering. Mark cockpit on sheeting and cut out carefully.
Start the Wing with the leading edge, cement 1 mm ply brace in position. Pin one leading edge to plan, add trailing edge, trips, ribs and spar in that order. Remove from plan and 'rock' the assembly to build the other half, and then 'neutralise' back for centre section to be flat on plan and add trailing edge and 3/32 in sheet brace to spars. Reinforce trailing edge joints with pins. Cement riblets in place after sanding.
Pin tailplane leading edge to plan. Add tips, gussets, 1/16 sheet at centre, 1/16 x 1/8 rib strips and 1/8 sheet ribs. Cement 3/16 x 1/16 spar in place on top of lower rib strips and then add 1/32 x 1/8 rib strips. These are best cut slightly oversize. Cement to trailing edge and spar first, bend over to leading edge, cut to correct length and cement. The Fin is built flat on plan from 1/8 sq and 1/8 sheet.
Carve the nose block from hard balsa and sand to shape while in place. Drill and fit brass brush and complete the prop assembly. Note that the rear cup washer is soldered to the shaft.
The fuselage should be covered with lightweight Modelspan and given two coats of dope. Wing and tail are best covered in Jap tissue and given one coat of dope. After covering, the cabane strut fairings, in. sheet fin strake, in. sheet tailplane key and windscreen can be added and the fin can be cemented to the tailplane.
Flying: Balance model under main spar, plus or minus 1/2 in. Trim for glide by adding packing under tailplane, approach maximum turns carefully, adding downthrust if necessary. Properly treated the motor will take 1,200 turns, plus 100 turns for pre-winding which will give flights of 90-120 seconds. If greater durations are desired the designer recommends using a balsa prop carved from a 1-1/2 x 1 x 12 in block, powered by six strands of 3/16 x 1/24 strip, 30 in long. This, however, will necessitate a slightly longer undercarriage to give the necessary ground clearance."
Update 13/09/2016: Added article page.
Supplementary file notes
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by Brian Lewis
Rubber F/F Parasol
all formers complete :)
got article :)
Found online 24/06/2011 at:
Format: • PDFbitmap
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User commentsI built this model when the plan first appeared and it proved a great design. Very easy to fly. Eventually flown with 6 strand motor - had a rocket climb!
Joseph-bloggss - 22/12/2013
Added colour pic of his nicely completed (electrified) Rubberdub model, thanks to Sundancer [model photo].
SteveWMD - 19/07/2014
The Rubberdub is one of several rubber to electric R/C park flyer conversions I have done and all have proved to be well worthwhile and excellent performers. I did build a F/F rubber powered Rubberdub way back, the orange wing/black fuselage model shown in one of the photos [more pics 004], and it was a nice sport flyer. However, the current electric R/C one (F-RUBB) is just as good and has the added advantage of not needing to be chased! The electric model is basically exactly as per plan, the only tricky bit being the all moving tailplane [see more pics 005, 006] which works well. Specification: Weight 6.1/2 ounces. Wing loading 6.5 oz/sq.ft. Motor BRC Hobbies 1811. Prop GWS 5 x 3 HD, battery 2S 320. Full throttle watts 19 at 2.3 amps gives gentle but adequate climb. Maximum watts per pound - 47.
Sundancer - 28/03/2016
This one was my entry into the RCG build-off for an originally rubber powered design model [see more pics 007, 008]. The basic design appealed to me (still does) as a particularly attractive and practical. Construction is basically balsa sticks like the original, but the frame was covered with doculam before the tissue applied. Power is a small .5cc Boddo Mills diesel which provides ample urge... Best regards,
Alan Wooster - 28/08/2019
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