Cloud Bound 4 (oz8565)


Cloud Bound 4 (oz8565) by Don Drury 1977 - plan thumbnail

About this Plan

Cloud Bound 4. Unlimited sailplane model. Wingspan 144in.

Quote: "If you want an Open Class machine that is the ultimate in sophistication, versatility and performance, the Cloud Bound 4 is for you. A radio controlled duration sailplane of twelve foot wingspan featuring a variable camber wing with coupled drag brakes and spoilers.

Thirty five years of modeling, mostly in free-flight categories, had led to a wealth of knowledge and instinct into what makes a winning competition airplane. All the theory and claims about design, airfoil, glide ratio, etc., is important, and a logical approach to modeling, but does not necessarily create winners. If it did, all models would be identical. If we look over the designs of the top ten models at any large contest, we find that wing spans will vary from 7 ft to 13 ft, wing loadings of 6.5 oz to 12 oz, high or low aspect ratios, with or without spoilers, fiberglass or built-up construction, V-tail or conventional, etc.

So what makes a winning model? First, of course, a good clean design free of problems like warped wings, loose couplings, a ship with good responses, positive reactions and consistency. In other words, a carefully constructed airplane. Second, and probably the most important, is the pilot. Luck can be a dominant factor in competition flying, however, the experienced flyer who knows his ship like the back of his hand is the one who's at the top of the heap consistently.

Last season my competition flying was disastrous, yet the three models I flew are all capable of winning contests and my flying ability is adequate. We could say the year was one of bad luck. Even though I feel luck is a big factor in competition, I can't accept bad luck for a bad showing.

I spent some time thinking of all the factors that contributed to last year's flying and made a problem and possi-ble solution list to see what 1 could come up with in the way of a sailplane with greater potential. Here is a summary of that thinking:

(1) Problem: Sloppy flying.
Solution: Practice, practice, practice- Know your ships' capability. Test fly in all conditions.

(2) Problem: Not enough altitude off tow.
Solution: Tow hook position is critical. Test fly under all conditions and move the hook accordingly. An electric winch will take a large ship higher than a small ship.

(3) Problem: Cross wind launch.
Solution: Again, a larger ship will work better in a cross wind than a small ship.

(4) Problem: Light to no wind.
Solution: Light loading, a large ship, tow hook position, high lift wing (undercambered).

(5) Problem: Windy day.
Solution: Faster ship on the tow. One that will penetrate to the top of the tow into the wind. Add ballast. Sharp leading edge for penetration, strong wing, clean ship, flat bottom wing, added ballast for penetration in the glide. Spoilers and/or flaps needed for landing..."

Supplementary file notes

Article pages, thanks to JHatton.


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Cloud Bound 4 (oz8565) by Don Drury 1977 - model pic


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