Lews Akromaster (oz7771)

About this Plan

Lew's Akromaster. Semi-scale model, for RC or CL.

Quote: "An article in AAM (February, 1970) on the Spinks Akromaster rekindled a desire to produce a semi-scale stunter. The full-scale aerobatic plane was designed by Charlie Hillard, under the sponsorship of 'Peppy' Spinks, for the sole purpose of winning the World Aerobatic Championship for the US. Charlie came close in 1970 with a third, but retired the Akro in favor of the Pitts Special to win the big one in 1972.

The Hillard/Spinks Akromaster looks much like a big model, and has proportions that are comparable to many good CL stunt ships, while approximating an RC pattern ship. I claim to be one of the world most frustrated modelers in that I like Scale, Stunt and RC - and this plane can supply all three. My Akromaster can stand at the top of the class when it comes to versatility. You can tailor your own Akromaster to do just what you want, whether it be CL Stunt Competition, Stand-Off (Sport) Scale, RC Pattern, or just a plane to fly for fun.

My first project was a 6 ft semi-scale RC ship which still flies well, but lacks the finesse and agility of the present model.

The CL version got its first real test in the 1971 FAI finals, in which I had to settle for a respectable seventh. I would describe the model in much the same way a British expert did: It is a sheer delight to fly. Because of its simple, uncluttered lines and colorful paint scheme, he declared it: one of the most beautiful airplanes I have seen.

Staying in the usual rut of most competition stunt fliers, a new model was finished just before the 1972 NATS. After a feverish trimming and last minute practice, it garnered a fourth. My cohort Randy Hancock came up with a fifth in Senior Stunt flying with an Akromaster. Randy repeated his fifth-place standing in 1973, but I fell to tenth trying to trim another new plane and harness the power of an HP 40. The HP is a fine engine, but don't try to work one into a stunt engine when you have limited time. I have had best results with the ST 46, but I'm still searching for the right 40, so that .015 lines rather than .018 can be used.

A hybrid RC and/or CL Akromaster was created just to prove a point and satisfy my own curiosity. The plane was flown CL for the first 15 flights. It showed full acrobatic capability and was trimmable for competition. The flaps were fixed in position, an RC unit installed and away it went, much to my pleasure. The RC flight characteristics were good and fast. I am sure the full potential of the plane was not demonstrated because of my lack of expertise.

During the Mint Julep meet, Dave Brown (RC pattern expert) did a Figure M with my Akromaster even with the low power caused by the exhaust-off tube (which I later removed) and wrong prop size. The next day at the Mint Julep I flew the Akro in my first, last, and only RC meet, for a ninth in Stand-Off Scale.

The plane did its part, only five points behind the top score on the ground. However, in the air my stick capabilities let it down and we settled for ninth out of some 20 entries. The big thrill of the flight was when I found my Akromaster stacked above a real plane that had been waved off due to the closed runway. I applied full throttle, the real plane was left behind, and I went ahead and made a left turn out.

This plane is basically simple, but the novice should first look elsewhere for the fundamentals or have experienced help. For this reason, I shall not go into the usual 'glue A to B' sequence of construction. Pick your poison, be it CL, RC, or Stand-Off Scale, and let's go at it:

CL Precision Aerobatics Version: Even here a chance for plenty of versatility presents itself, and the quality of the final product is up to you. Select wood as if you were using an 049 for power. You will need to decide the type of motor mount set-up preferred. I like the Kraft-Hayes because of its flexibility. Note that a 1/4 in firewall replaces the 1/8 plywood used in conjunction with hardwood beams when a radial mount is used.

The model under construction utilizes a tank inserted through F-3 into a compartment specially built between F-3 and F-1, which is quite similar to the RC method of tank installation. Both vents come out inside the cowl and engine compartment; one is for muffler pressure and the other is plugged after the tank is filled. This method of removable tank becomes impractical if you choose not to make the wing removable.

Note the difference in wing position between the removable and fixed versions. The dihedral in the removable version, in effect, produces the same aero-dynamic position..."

Lew's Akromaster by Lew McFarland, November 1974 AAM.

Update 06/06/2016: article pages, text & pics added, thanks to RFJ.

Supplementary file notes

Article pages, text & pics.

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