Sonic Booms (oz5812)

About this Plan

Sonic Booms. Radio control sport model. Twin Boom design.

Quote: "An easy to build 1/2A airplane with personality.

It all began one evening after finishing reading the February '79 issue of RCM. I thumbed through it again to look for the design contest advertisement, which I had only glanced at the first time through, to get a clearer description of the rules. After reading the rules and looking at the fabulous prizes, I tried to think of a unique design.

I pondered the subject for a considerable amount of time until, finally, at 2:30 am, a unique configuration struck me. I had often been drawn to twin-boomed aft sections which I've seen on scale planes such as the P-38 Lightning. I thought, how about incorporating booms on a 1/2A sport ship? That simple thought alone was the beginning of the 'Sonic Booms'.

Quickly, I sketched out my idea on the first paper and with the first pencil I could find for fear I would forget about it the following day. Next, the task of drawing up a set of construction plans was begun. These plans, like the earlier sketches, were done on the first paper I could get my hands on which was, believe it or not, the back of a bowling alley score sheet!

I had a small list of requirements that the plane was to fulfill. Among them was the desire for a small, economical (1/2A) plane which could be easily built and show fairly maneuverable flight characteristics. I was aiming for a light wing loading of about 12 to 15 ounces per square foot because dead-stick was the only way it was going to land (purposely, anyway) and a light wing loading would give a little longer flying time for planned landings as opposed to the landing of a 'streamlined brick' with an astronomically high wing loading. The weight necessary to achieve this wing loading is between 24 to 28 ounces. If you are as heavy handed as I am with the glue bottle, you may find that building it light may be difficult, but not impossible when built utilizing cyanoacrylate adhesives for most of the ordinary joints and epoxy or white glue for points of high stress, like the firewall. It had to be large enough to house standard size radio equipment because the only radio I own is standard. All of these basic requirements started to flow onto the drawing board.

The fuselage was drawn as a basic box, utilizing only thick (1/8") sides and hollowed blocks for rounding the wingtips and the shaping of the rearward end.

Upon completion of the drawings, I wondered to myself if I had bitten off a little more than 1 could chew. It looked a bit large for a TD .051, but then again, they always look bigger on the plans. Just to play it safe I built it with the lightest grained balsa I could find. The use of light balsa proved to be a factor in my favor as far as its performance, but let's not get ahead of the story.

Construction. Wing: If you only have a little experience with cutting foam wings, it would be advisable to get some help, even if your helper has had no experience. Wing cutting, for the most part, is a two person operation. The procedure of cutting the wing is as follows..."

Update 5/5/2024: Replaced this plan with a clearer copy, thanks to theshadow.

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