Humbug (oz11311)

About this Plan

Humbug. Control line stunt model, for .19 engine.

Quote: "An unconventional approach to design and construction, with an eye toward drag reduction, results in this unflapped stunt plane that outperforms any configuration with as little as a hot .19 mill. Humbug, by Rob Baron.

Since 1946 we've had a nagging suspicion that there was a better way to approach the U/C stunt pattern. Took us 20 years to find it! Now that we've got it - no one, except Bob or me, wants it. The Humbug geometry is what you get from assuming that a winning flight occurs in the AIR. The high (7:1) aspect wing and 10:1 stabilizer fly through corners. Low pitching inertia gives rapid response to control force so the pilot can precisely guide the machine through the intricate Close Tolerance maneuvers. A dispassionate review of the rules does not place any significance on appearance except that a clean, smooth, neat finish on an original airplane should be worth 30 points.

Anyway, Bob found us standing around, admiring the first Humbug drawings in 1966. He built one and has been out among 'em, bringing the concept to peak perfection. Since success is 90% perspiration, the credit and/or blame, should be his. When Bob decided to use his Humbug in competition we agreed that it might take a year to educate the PA troops. We missed it a bunch.

One final warning. About the time you get your Humbug tuned in, you will be finished with flapped machines. OK, Bob, tell it like it should be.

The Humbug IV is a highly refined precision aerobatic stunt plane that can easily outperform the conventional flapped U/C stunter. It is also guaranteed to frustrate anyone who thinks the path to U/C stunt glory is via flight performance. The Humbug IV has been maligned as too ugly, too hard to judge, too fast, too sharp on corners etc, ad nauseam. The one aspect that has never been questioned is its ability to execute the AMA pattern with no apparent effort on the part of plane or pilot. When you tire of losing contests, you can fly the pattern on 90 foot lines by dropping in a Super Tigre .40.

The basic approach to achieving high performance has been through greatly reducing the drag over that of conventional designs. The methods of drag reduction include:

(1) Reduced frontal area.
(2) Low total weight and wing loading.
(3) Reduced interference drag by contouring the fuselage into the wing.
(4) High aspect ratio wing and tail surfaces.
(5) No flaps.
(6) Use of .012 diameter control lines allowed by a .19 engine.

Secondly, a significant decrease in pitch inertia was achieved through the use of a light engine and special structure. The low inertia makes response entering and exiting a corner essentially instantaneous.

The flying characteristics can best be summed up as stable yet very responsive. The actual level flight speed is only 60 mph on 70 foot lines resulting in a five-second lap. In maneuvers, however, there is only a very slight loss in speed which accounts for the many comments about the high speed. A conventional airplane, in comparison, is going only 45 mph during a maneuver. The most obvious place where high performance is evident is when it climbs vertically through the horizontal square eight the second time around. The middle and upper right hand corners are just as easy the second time as the first. The feel, while not sensitive..."

Direct submission to Outerzone.

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