Aries XJW-120 (oz14304)

About this Plan

Aries XJW-120. Radio control giant-size sport aerobatic model.

Quote: "Introduction: I have always been fascinated by the aerobatics performed by the model aircraft, especially those that are scale or semi-scale. I found them interesting and enjoyable to fly. Although I admire individuals who take on true scale projects, that isn't my forte. I don't have the patience, skill, or discipline to build scale. So I will leave those projects to the scale builders.

The Aries XJW-120 monoplane is very much like many of the popular semi-scale aerobatic aircraft now flying. Although similar in appearance to some models, I hope I have added a few performance enhancements. Some of the planes that have influenced the design and development of the Aries, are the Caps, Lasers, Extras, Sukhois, and the Ultimate Biplane. There are features in these aircraft that are of considerable interest to me. This is my attempt to

duplicate these features in the Aries. The challenge is to develop a design into an aircraft that flies well, has good aerobatic capabilities, and is a comfortable flier for a Sunday afternoon. Also, the design must come in light enough so a 4-stroke 1.20 or 2-stroke .91 engine would provide ample power to give good performance and retain the scale appearance. As you know, in most aircraft of this size that require the 1.20 4-stroke, the cylinder head protrudes through the side of the cowling. I like to hide the cylinder head inside, so the Aries fuselage was made wider and cheeks were added.

The Aries XJW-120 was developed around the OS FS-120 4-stroke engine and performed exceptionally well with that power. However; to further evaluate the performance of the prototype with different power installation, the O.S. FS-120 4-stroke was removed and replaced with an ASP .91 2-stroke engine. The retrofit was completed and the performance is still excellent. Even the C.G./balance worked out okay.

To be sure that the aircraft would perform reasonably close to what was expected, design parameters were kept to known moments and proportions for good flying results in model airplanes. The wing aspect ratio is 6:1, with 14% airfoil. With this wing planform and a fairly long nose moment, the plane grooves with little tendency to tip-stall at low speeds. In looping maneuvers, the model keeps a fairly constant speed.

The empennage including the control surfaces have a slight airfoil for aesthetics and help neutralize unwanted aerodynamic forces. The wide fuselage is for allowing room in the nose area for the cylinder head of the larger 4-stroke 120 engine and makes for easier installation of radio equipment and other internal fuselage parts. When studying the plans, you will notice the near proximity of the wing saddle to the cockpit floor. This is a narrow area so the builder must do the construction just as it is shown on the plans, to be assured of not having any structural integrity problems.

When mounting the servos in the fuselage, be aware that it may be necessary to cut relief openings in the wing so the wing will not interfere with servos when it seats in the fuselage saddle.

The wing uses the NACA 0015 type airfoil which has worked out very well for me. I took the liberty of making a few minor adjustments to the airfoil ordinates at the various camber stations. This was done to adjust the percentages of amplitude above and below the airfoil Datum Line. I believe these modifications make a more efficient wing planform. So far, I have not seen any unwanted flight instabilities while using this airfoil.

This airplane is not for the beginner builder or flier. It will require a certain amount of building and flying experience. I would recommend it to anyone who has built and flown low wing or pattern type aircraft.

Before starting construction, take the time to cut out a kit of parts, rubber band or tape them together, and put them in one of your old kit boxes. Oh, one other thing, be sure to mark them so you will know where they fit. When I cut out a kit, I have an extra set of plans to cut up, then cement the parts with 3M Spray Mount Artist's adhesive to the wood to be cut. I find that the paper is easy to remove and it leaves very little residue on the wood. After all this - if you are still interested, go back to the text and drawings and study them before starting construction..."

Direct submission to Outerzone.

Scan by MarkD, cleanup by Circlip.

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