Sunny (oz14524)


Sunny (oz14524) by Mark Smith 1978 - plan thumbnail

About this Plan

Sunny. Radio control sport biplane model. Wingspan 40 in, wing area 559 sq in, for .15 engine.

Direct submission to Outerzone.

Quote: "Hello, Here is a new plan for your site. Attached is a scan of an old plan from Mark's Models. It is the Sunny Biplane and was designed by Mark Smith. It is from the late 70's I believe. It could probably use a good clean up [fixed now]. Thanks for your great website."

Update 27/4/2023: Added kit review from RCM, February 1978, thanks to RFJ.

Quote: "RCM Product Test: Mark's Models Sunny.

The Sunny is a sport cabin-type biplane manufactured by Mark's Models, designed by Mark Smith, designer of the Windfree, Windward, and Wanderer sailplanes.

The kit consists of a box-type fuselage, built-up wings, and solid balsa tail surfaces. The hardware with the kit includes a dural main gear, 1/16 diameter wire for the steerable tail wheel, hardwood engine rails, wing tie-down dowels, pushrods, and all the necessary screws, nuts, blind nuts, and washers.

The kit design and manufacturing are excellent. All the parts fit with no adjustments being necessary. The plans, instruction manual, and construction photographs are very good. Anyone who has built one or two kits should experience no difficulty in building the Sunny.

The RCM prototype was built using Goldberg Jet cyanoacrylate, Gluit sandable aliphatic glue, and Devcon 5-Minute epoxy. HobbyPoxy 2 was used to fuelproof the engine and fuel tank compartments. K&B polyester resin was used in applying the fiberglass reinforcement to the wing center sections and to coat the inside of the radio compartment. We used Super MonoKote to cover the entire airplane.

There are several features in the design which we feel are worthy of note. The 1/8 x 1/2 plywood servo rails fit into a groove machined into the side of the fuselage. This makes it very easy to adjust the servos fore and aft for balancing.

The main landing gear is secured by two wood screws which pass through oversize holes in the 1/8 plywood mounting plate and are secured to a 1/16 plywood nut plate; in the event of a bad landing, the screws will pull out of the nut plate without ripping out the bottom of the fuselage.

The nose block has been sawed at an angle so that when the engine mounting rails are epoxied in place the engine will have the correct downthrust.

The accuracy of the fuselage components was so good that only very light sanding was necessary to align the wings and tail.

After installing the Cox radio and servos, and the OS Max .15 engine, our prototype was tail heavy. We moved our flat battery pack into the tank compartment and placed 3 ounces of lead in a cavity under the engine. We covered the cavity with heavy paper and coated it with epoxy to prevent fuel seepage. Our prototype met the design ready to fly weight of 56 oz.

The first 2 flights were hand launched so the trim could be set. Elevator was very sensitive so the pushrod clevis was moved to the outer hole in the control horn. The rudder was set for maximum throw. At this time, we were ready for the take-off on a grass field. The lift-off was very quick and the pilot has to be alert to keep the nose down. It will lift-off before sufficient flying speed is obtained. Using the specified downthrust on the engine that the plans call for, it still wants to climb. It has tremendous lift for its size and power.

The rudder area limits the roll rate and we couldn't snap roll it. It will fly inverted and, when brought into a stall attitude, the left wing will stall first and drop. If the engine is throttled back, or if the tank runs dry, the Sunny will soar with a flat glide which gives you ample time to set up for landing.

As an experiment, we added 3 sq in to the rudder area. This enabled us to do tighter turns, rolls and snap rolls. We do not recommend this modification. It was done simply to see what the snap roll capabilities were on this little bipe. This modification made the rudder extremely sensitive.

Some of our landings were very rough, however, the Sunny came through very well. It has a strong airframe and wing structure.

All of our flight testing was performed using K&B 500 fuel and a Taipan prop.

The Sunny is a nice little bipe and a good buy at $32.95 that will provide a lot of enjoyment."

Supplementary file notes



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Sunny (oz14524) by Mark Smith 1978 - model pic

  • (oz14524)
    by Mark Smith
    from Marks Models
    40in span
    IC R/C Kit
    clean :)
    formers unchecked
  • Submitted: 14/04/2023
    Filesize: 975KB
    Format: • PDFbitmap
    Credit*: MikeBohannan
    Downloads: 561

Sunny (oz14524) by Mark Smith 1978 - pic 003.jpg
Sunny (oz14524) by Mark Smith 1978 - pic 004.jpg
Sunny (oz14524) by Mark Smith 1978 - pic 005.jpg
Sunny (oz14524) by Mark Smith 1978 - pic 006.jpg
Sunny (oz14524) by Mark Smith 1978 - pic 007.jpg

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