Hi Hawk (oz16850)

About this Plan

Hi Hawk. Radio control sport trainer model. Wingspan 45 in, for Enya .15 engine.

Note this plan uses the Sig Foam wing, although sheet 2 shows alternate built-up wing.

Quote: "Stability, strength and smooth response are hallmarks of this 15-powered sport cabin job for elevator, rudder and engine. Hi-Hawk, by Bob Harrah.

Aeromodeling suppliers keep coming with new products to advance our hobby. Two of the newer items that show potential for the creative modeler seem to complement each other. Orbit Electronics has developed a small, compact, moderately priced radio, called The Hawk, and Sig Manufacturing has designed a new 45 inch constant-chord wing using a Clark-Y type airfoil. This combination has opened up a wide selection for potentially well designed airplanes for sport flying. Since many of the older and stabler designs used the Clark-Y airfoil, the new Sig wing seems to be what the doctor ordered.

The 'Hi Hawk' is the accidental result of this - but let's hold on a minute. I am getting ahead of myself. The new wing and radio sent me on a search for a sport flyer design airplane (with good looks, durability, stableness in the air and good dead-stick capabilities) that had not been previously kitted or featured. Old magazines, books, and some of John Pond's 2000 or more plans were cast aside in the search. Then Russ Barrera pointed to the ceiling of his model museum (nestled in the beautiful San Marcos, Calif, Valley), and said, How about that one? What is it? I asked, hating to admit I didn't know. Russ said, it's right on the tip of my tongue, Bob - and it stayed there for about a week. Then the phone rang and Russ blurted out, it's the Tiny Champ.

Russ couldn't find any three-views, but loaned me an incomplete model that was started in 1969 by the late Vic Harden. I started scaling from the model; in fact, I went feverishly into the lumber pile and started building. The Tiny Champ built like a dream and appeared to have all the features for which I was searching. Soon, she was complete and ready to test fly, but I wanted the three-views to authenticate its scale for the story; no luck. I frantically contacted Bill Warwick, the builder and de-signer of the full-size plane. He said there were two built, but he had no drawings.

Well, I couldn't put scale on the plans without some verification. Russ understood my dilemma and was able to find a picture in an old aviation magazine; from mutual friends he found a couple of slides. Projecting these up on the wall and studying them with a magnifying glass, I found I wasn't close enough to scale, so the Tiny Champ died as a scale sport flyer. But the design was still there and looked good, so I changed the design to make it easy to build, and the lines were altered enough to escape the Tiny Champ look.

Since I was planning to test the new Orbit Hawk radio, I dubbed this model the Hi Hawk. I was testing Sig's new wing too, but "Hi Sig" sounded too much like a telephone conversation. The resulting design, though not scale, gives all the desired features for small-field sport flying, and it has already survived a few rough landings.

I am not sure that all modelers have shaky knees and twitching hands on every flight - some seem real cool. However, most whom I have met, and with whom I have flown, have second thoughts on every flight. I guess that's what makes it so exciting. Those of us whose planes have had a hinge come loose, a servo connector vibrate open, or (heaven forbid) a wing snap in two during pattern flying, have lots to keep us on edge as we taxi our planes out for takeoff. Not to make excuses, but this flier has tried to make his planes fool-proof, to be safety conscious and to make planes easy to fly, clean and maintain. Hi Hawk is an attempt to be a combination of the above.

The design necessary to insure durability usually requires added weight, resulting in hairy approaches with engine off.. This design is a compromise approach: The slower airfoil, with good lift characteristics such as the Clark-Y, makes it possible to carry a heavier load and still maintain stable flying with a slower stall speed.

The use of a rubber hold-down wing and wheel mounting aids in reducing or eliminating damage in marginal hard landings. The pop-off wing and landing gear may not look pretty, but neither do the fuselage structures when scattered all over the field, especially when the scattering is caused by a small mound of dirt or rock after an otherwise safe approach. If you are good enough and lucky enough to be flying off a smooth landing site, then the wing and wheels can be mounted permanently with standard attachments. But the real fun is to keep them flying.

The fuselage is designed to look like an airplane, while maintaining easy engine access and change. Other features include: an isolated fuel area, one- or two-ounce klunk tank (shown), with room enough for many more ounces for duration fliers, and a large access area to servos for quick adjustments. The battery and receiver area have plenty of room for foam (not rubber). An optional hatch in the bottom, as shown in the pictures, is recommended. All formers from the cabin to the nose are plywood. These formers add very little weight; the extra strength of plywood substantially reduces the risk of damage to the receiver, batteries, servos, etc., during crash situations, by preventing the components from bursting through the fuselage at impact.

Orbit has introduced some innovations in linkage and attachments. There are various methods I have used with success, but all had shortcomings. The use of plastic control rods works fine, except during temperature changes; when these were used in long lengths they would expand and contract depending on the temperature..."

Direct submission to Outerzone.

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