Eyeball II. Radio control patern model. Uses a foam cut wing.
Quote: "Exciting mid-wing pattern machine that can hold its own among the best in contest flying. Designed to meet all of the requirements of the unusual pattern maneuvers it does it best when under full challenge. Good looking and properly finished it can also win in the best finish events. Our author had not bent his efforts in this direction, it still was capable of a good third at recent Spokane International meet, also 4th against the best in stunt. Eyeball II, by Art Schroeder.
Since the introduction of the Astro Hog (oz4756) many years back and the contest record of the low wing aircraft that followed, virtually every R/C modeler has accepted the theory that an all-out, competition R/C design must carry its business surface on the bottom of the fuselage. Occasionally a Doug Spreng or John Roth tried to paddle against the mainstream with the Stormer (oz5794) or Citation (oz5674); but never with the impact of the Taurus (oz612) or Kwik Fli (oz6526). The theory of the low wing aircraft has never been quite clear to this author since so much of the time the low winger is a high winger - that's any time its bottom is on the top, like when inverted, Charlie! Eyeball, to the contrary, has much the same configuration whether upright or inverted. As far as it's concerned it never knows the difference - neither does its pilot, but that's another story.
About a year ago the mid-wing be-came a personal obsession—a quality word for my stubborness that resulted from many fliers telling me the idea was for the birds. Incidentally, I've never seen a low wing bird! As the thought took root, a decision to go all the way to a zero-zero configuration was made. The thrust line, wing and stab center line were to coincide, no dihedral (only bottom taper) in the wing and lateral area was to be as close to equal as I could get and still have the thing look like an airplane (some of the first sketches sure didn't). Knife edge flight and the point rolls dictated generous lateral area; spins, reverses and stall turns called for a large rudder. All of this added up to Eyeball. Why the name? Some years ago a good friend, Jim Dean, of Cumberland, Maryland told me that with people who spend a lot of time around airplanes, that which looks right will probably be right. Eye-ball looks right to me, I hope it will to you.
Some questions have been raised about the root-tip relationship (15%-13%). Most designers are advoca-ting a thicker percentage at the tip. All I can say is that this wing exhibits no tip stall tendencies when slowed down. I believe that 15% (as does Hal deBolt) is the maximum useful thickness for our purposes. The overall design is quite clean and is pretty constant in its speed throughout the pattern - speed is quite high, outrunning most of the current planes flown today. In fact Eyeball should be a pretty fair open pylon com-petitor. The next one is a 600 sq in version for Formula II.
The local prophets of doom were ready to take any odds that the in-line relationship of wing to stab would result in oscillations, flat spins and other assorted disasters. Eyeball apparently never looked over the aerodynamic books since its pitch movements are the smoothest I have ever called for.
Two wheels are my special drag reducing device, guaranteed 30% reduction over the usual trike gear. The two wheel gear exhibits no ground handling problems at all. When taking off hold full up for about five feet and then let go, it will run out as if on rails. Basic ground maneuvers are accomplished with up held in as well.
Roll capability of the Eyeball is equally as smooth as pitch, as long as you stay within the design parameters of surface throw and balance point. Very little corrective elevator is needed in the three roll series.
An interesting quality of the design become apparent in its early flights. While it is fully capable of the entire AMA pattern, at slower speeds it makes a fine trainer. When built light and powered with a good 45 - 50 I believe anyone past the Tri-Squire (oz5667), champ stage will find a slow Eyeball to their liking.
Those of you that just bought a Kwik Fli (oz6526) kit, go ahead and build it (it's a fine airplane); those of you that are searching for something different try Eyeball, we believe you'll be glad you did.
Prefabrication of all sheet pieces, formers, sides, doublers, stab pieces, motor mounts and plywood parts speeds construction. My first step is to literally kit the airplane before I do anything else. Two hours will set you up with a full set of parts. J
The fuselage is built in a simple jig made of trued up pieces of 2 x 4 x 40 in attached to a presswood foundation 40 x 6 x 3/4 in. I trued up the 2 x 4 in a planer. The jig pieces for the formers are made of 1 x 1/2 x 6 in pine. The photos should make the jig construction and use evident. The top of the jig pieces represents the thrust line. The top fuselage center line should be scribed on the jig pieces before construction begins. Each former should bear a line representing the side and top view center lines. While the jig is not absolutely necessary (I'm sure experienced builders will see other ways of constructing the fuse) it does make life easier and results in a 100% true fuselage; and in R/C accuracy is the name of the game.
1. Set formers 1-6 in the jig upside down, be sure reference lines drawn on the formers are accurately positioned on the jig.
2. Contact cement the 1/32 ply doublers to the 1/8 hard balsa sides. 3M spray contact cement is excellent for this operation.
3. Run the motor mounts into the cutouts on formers 1 and 2. Secure the mounts in place with plenty of epoxy cement. Check alignment carefully and constantly.
4. Using bits of scrap 1/4 in square balsa draw the sides against the formers at the jig level, at the same time pin the sides directly to the formers at the bottom of the fuse (remember in the jig the bottom is at the top). Use Titebond for all joints except on formers 1 and 2; there I recommend liberal amounts of epoxy. Prior to all of this I hope you have worked out some kind of wax paper separator between glue joints and the jig (I used pieces of masking tape)..."
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