Acro Star (oz6256)

About this Plan

Acro Star (AcroStar). RC sports biplane model. For .40 or .60 power. This is the RCM Acro-Star. The design was also later kitted as the Airtronics Acro-Star.

Quote: "We tried to capture the essential appearance of the EAA bipe, using moment arms and proportions that have provided good flying characteristics on other biplane designs we have flown. This design is not scale but most of our friends who have seen it thought it was. By changing the headrest outline and interplane struts you can create a Smith Miniplane, or several other similar homebuilt aircraft.

One of the nice things about homebuilt aircraft is that they are as individualistic as modelers, and modifications of the basic design are many and varied. This model packs 820 square inches of lifting surface into a compact sized ship that, when fully assembled, easily fits into the back of a Pinto Station Wagon. Prototypes have been flown with engines from .40 to .60 size, and weights between 5-1/2 and 7 pounds.

The prototype shown in the photos is powered by a Veco .61 with muffler and weighs 6.5 pounds with an Orbit 4 channel radio system and PS-6 servos. With 5.7 square feet of area this works out to a wing loading of 18 ounces/sq ft. Powered with a good .40, such as the OS Max or K&B FR .40, the Acro-Star is a great sport ship for the Sunday flier. With a .60 up front it will fly the pattern and execute the vertical maneuvers with ease.

Our prototype is dressed up with optional features such as the inter-plane 'N' struts, wheel pants, cabane fairings, pilot, etc. These add to the looks but the simpler basic version shown on the plans flies just as well. The widespread use of electric starters ensure easy starting with the inverted engine shown. If you prefer an upright engine, just turn it over and cut a hole in the top cowl block and raise the tank slightly higher.

Structural design is conventional, with a few innovations to help make the job easier. Wing construction is almost the same for both wings, and both are easily built on a flat surface without special jigs. The lower wing has a slight amount of dihedral to prevent a 'drooped tip' appearance, and the ailerons are cut out and hinged after the assembly is completed for easy alignment.

The spruce spars and full span shear webs provide quick building and a very strong warp-resistant structure. Medium weight 3/32 sheeting ensures smooth covering and provides a little extra material for sanding, with only a slight increase in weight. The solid tail surfaces are easy to assemble and finish, and angling the grain as shown provides warp resistance..."

Supplementary file notes

Article pages, text and pics (incomplete), thanks to hlsat. Also, article part 2 (remaining pages) thanks to ar196.

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