Alphacon (oz4609)

About this Plan

Alphacon. Control line trainer model.

Quote: "Beginners' Control Line Stunt Trainer. Alphacon, by Henry J Nicholls.

THE Alphacon has been designed with two objects in mind: simplicity and ruggedness of construction, and a sound aerodynamic performance in line with its designation as a stunt trainer.

The wing is built-up and has fairly thick symmetrical section of good CL, characteristics, this being in keeping with the latest CL practice. Trailing edge is built up from 1/16 sheet, the top and bottom, and not sanded downto a knife-edge at the give rear, leave as near the full 1/4 in thick as possible. LE is 1 x 1/2 in medium stork, ribs and TE hard 1/16 sheet.

Two extra bays may be added to the wing for motors in the Ohlsson 23 or Arden 199 class. This increases the span by 4 in, and the area by 20 sq in.

Fuselage is as simple as it could be, the prototype having been built without even one ply former, yet it has proved amply strong to withstand many spinner landings under full power.

The bottom is 1/4 in sheet, and should be lightly scribed with a cutter across the grain every 1/2 in, the cuts being filled with cement. Then pull the bottom up into shape, bending according to the profile view on the plan, and as the cement sets it will pull the curve in permanently.

Pre-cement thoroughly and add formers, engine bearers, undercarriage box and blocks. Add sides, pre-cementing all joints as before. Pin well to retain shape while cement sets.

The control system is standard practice and may be added as soon as the fuselage sides have set. The ply platform has the 6 BA pivot-bolt screwed in, the head being cemented to lock. Platform is then Durofixed and screwed to the engine bearers. Bellcrank is added and finally the control rod is threaded through from the rear and the bellcrank is nutted down. Make sure there is clearance for the control rod through all formers for the full movement of the elevator. If not, increase the size of the holes until there is. Adjust to minimum movement for first flights (inner bole on bellcrank - bottom hole on elevator horn).

Add fuselage top sheeting and when set add tail unit. Thoroughly pre-cement all surfaces for the canvas or tape hinges for the elevator. Smother in cement and massage well in with the finger tips. Same applies to fixing the elevator horn.

The original fuselage and tail unit were completely covered with rag tissue before doping, using clear shrinkng dope as adhesive.

Finish is obtained by giving three coats clear or glider dope on top of the tissue covering and finally three coats of colour, lightly rubbing down with fine Garnett paper between coals. Wing tissue has two coats clear and two coats colour dope only.

If fitted with a petrol motor, correct CG trim is preserved by fitting coil and condenser dose up to motor and battery near TE of wing.

The original is shown with the ED Competition Special, with which it new extremely well on the smaller wing.

Other suitable motors are 2.2 cc Majesco, 2.8 cc Allbon, 3 cc Marager, 3.36 cc Ouragan amongst the small diesels. Use the bigger wing for the over 2.5 cc motors.

Amongst the smaller petrol motors (all American I'm afraid), the Bantam, Arden 099, and Ohlsson 19 will all do well on the small wing. On the larger wing try the Ohlsson 23, Arden 99.

Propellers should be about 8 in pitch, the diameter being suited to the motor used. My ED took a 10x8 or a 9x8 very well.

Finally, I should be very glad to hear of any results obtained with this model by readers, and at the same time should be delighted to answer any questions regarding the design. Happy landings!"

Direct submission to Outerzone.

Supplementary file notes

Planfile includes article.

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