Tiny Twin (oz15474)

 

Tiny Twin (oz15474) by Aubrey Kochman 1964 - plan thumbnail

About this Plan

Tiny Twin. Radio control sport twin model. Wingspan 36 in, for (2x) .020 engines.

Direct submission to Outerzone.

Update 14/8/2024: Added article, thanks to RFJ.

Quote: "If you think you've experienced all the delights of radio control plane flight, wait until you try this lively little twin-engine rudder bird! One of the country's best known designers has come up with a sturdy, trouble-free beauty. Tiny Twin, by Aubrey Kochman.

Why a twin? Well, why do people climb mountains? It's the challenge and we wanted to try one since more and more modelers agree - it's the next big step in R/C.

We know the problems confronting twin engine operation, like starting two engines, getting them to beat together, run together and - the biggest - stop together. With a small ship such as 'Tiny Twin' powered by a pair of Cox .020 engines, these difficulties are greatly minimized. Fast starting is the rule rather than the exception of all Cox powerplants and especially of their .020 so the second engine is easily started within seconds of the first. They are also pretty well mated. That is, they all run pretty close to the same rpm. As to stopping together, well, that's another story. We never expected they would but the difference in run has so far only amounted to the few seconds it takes to start the second one. We have found that a left turn develops when the port engine cuts first. However, thanks to the C&S pulse proportional system which we utilized, corrections are easily made by trimming in a little opposite rudder. Practically no change in heading results from the starboard engine quitting first.

There is one proven method of preventing heading changes no matter which engine quits first. Ken Willard developed it hack in 1953 and it is still being used with great success by many free fighters. Stated simply, add a few degrees of left thrust to the port (left) engine and equal amount of right thrust to the starboard (right) engine. We haven't gone to this system simply because Tiny-Twin has been completely controllable on one engine. However, should you encounter drastic directional changes on one engine, give Ken's system a try. It really works.

Our completed model, painted and ready to fly weighed in at a shade over 16 ounces. This is a good weight as it allows ample control on a single engine. However, to match this weight it is very important that initially you spend a little extra time at the wood rack and choose your stock wisely. The plans indicate the various grades of lumber and if you adhere to these recommendations, the flying weight of your model should be much the same as our prototype.

The wing is more easily formed if 6 in wide stock is used. This is especially true of the top surface. The bottom surface may be fabricated from 3 in wide stock butt-cemented together so that the joint falls centrally along the full span spar. We used Sig contest balsa throughout. Cut bottom sheets to outline shape. Cut all ribs from 3/32 medium stock. Cement the inner leading edge to the 1/16 bottom wing sheet. Use a straight edge to insure a straight leading edge. Add the main and stub spars and then the ribs with the exception of the center rib.

The opposite wing panel is joined to the first in the following manner. Cement the plywood dihedral brace to the rear of the main spar of the partially completed panel. Block up this panel so that the tip is raised 5 inches..."

Supplementary file notes

Article.

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Tiny Twin (oz15474) by Aubrey Kochman 1964 - model pic

Datafile:
  • (oz15474)
    Tiny Twin
    by Aubrey Kochman
    from American Modeler
    July 1964 
    36in span
    IC R/C Multi
    clean :)
    all formers complete :)
    got article :)
  • Submitted: 19/07/2024
    Filesize: 512KB
    Format: • PDFbitmap
    Credit*: dfritzke
    Downloads: 419

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