Joss Stick (oz11804)

About this Plan

Joss Stick. Tailless rubber model.

Quote: "Hi Steve & Mary, Also from the May 1958 Model Aircraft, the Joss Stick, a rubber powered flying wing. I have included the companion article 'The Tailless Model'. Cheers,"

Quote: "JOSS-STICK the ideal introduction to tailless flying.

THIS model was designed mainly for use at the All-Britain Rally in the rubber driven tailless category, and if you have been disheartened at this meeting (Radlett) in the past by watching your latest super-contest F/F job disappear permanently over the perimeter fence on its second flight, well this model is just the job for you to take there this year. None of its competition flights in the past have taken it out of the field, with tailless there is no queue to wait in, and best of all, it can win.

Its competition record includes a win at the 1957 ABR and 2nd in the 1955 Lady Shelley, it also makes a good sports model and is a ready vehicle for development as it can be rapidly converted from pusher to tractor. Good stability is a common feature of tailless designs, and the only breakages with the original in three seasons of flying were rubber motors, and tissue.

Start construction with the two fuselage sides laid down one on top of the other, over the plan. When dry remove and separate them and insert the cross spacers; add the ply nose former, cover with lightweight Modelspan, and that's that.

Cut out a set of ribs, using one of the ply root ribs as a template, mark off and drill the dowel holes accurately if you wish to avoid difficulties later, during assembly. Cut the slots for the spars, then divide the ribs into two equal sets and run through them enlarging the slots to an angle for the sweepback, not forgetting to make each set of opposite hand.

Notch the trailing edge to receive the ribs and assemble flat on the plan, sand the edges to section. Try in your joining dowels and file the holes in the ribs as necessary to bring them into line, grease the dowels and cement the paper tubes in place. Your wing should now have approx1-1/2 in dihedral under each tip. The centre bays can be covered with 1/32 sheet balsa if you want to make your model really strong.

Cover the leading edge from the top spar, around the LE and back to the bottom spar with lightweight Modelspan, steam in the washout and hold until dry. Give it a coat of dope and pin down on a flat board, with the TE packed up to give a little excess of washout (some will warp out). Now cover the entire wing with lightweight Modelspan or jap tissue (the leading edge now becomes double covered), dope, and pin down, again using the washout template, for - at least 24 hours. to dry thoroughly.

Check the finished wings; no wash-in can be tolerated but an excess of washout is no disadvantage provided that both amounts are identical. Add the tip fins and elevons, setting these latter up with the aid of the template. Make a cradle from scrap balsa and cement it under the centre-section so that the wing sits on the fuselage without rocking about.

Carve a prop from the blank shown, making it of opposite hand to the usual tractor screws; you can, of course, purchase a commercial propeller, and use it by winding up the rubber backwards. If you intend to try the model as a tractor this does not apply and you can also with this set-up use a folder made from sheet in the usual way.

Make up a motor of six strands of 1/4 x 1/24 x 30 in long, lubricate well, attach the wing securely on fuselage with rubber bands and put on your running shoes.

Flying: Adjust the glide by moving the wing fore and aft along the fuselage to find the best position; it should not prove very sensitive. If the model stalls when the wing is right back along the fuselage add a little plasticise to the nose. When you are satisfied put a few turns on the motor, increasing the number with each launch.

When the glide is perfect, do not move the wing again but mark its position for keeps. Make power adjust-ments by altering the thrust line, using downthrust to correct any looping tendency, and side thrust to get a spiral climb. The model should circle either way without loosing height, but if the circle is too tight for comfort increase the washout on the wing outside the circle (by steaming).

The suggested motor will take about 800 turns, you can if you like use a longer one but watch out for bunching. Don't be too satisfied with the first trim you strike but search for a better one, the duration should be better than 90 sec in still air, and about 120 sec with good rubber on a warm summer day. If you want to fly when thermals are around rig up a DT; an external folded paper parachute, fuse operated, will prove most suitable. The original soars well and once topped 7 min.

It is possible that due to different weight distribution among the components, and slight warps, each machine will develop its own peculiarities and the builder will have to devise the answer, but trimming for a stable and satisfying flight should prove easy to anyone who has flown an ordinary rubber model."

Direct submission to Outerzone.

Supplementary file notes

Article.
Article 2 (title: The Tailless model).

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