MegaTech R/C Real World Helicopter Series Bedienungsanleitung PDF herunterladen (Seite 60)

DESIGN AND BUILD AN RC BIRD MODEL

The tip feathers operate in a region of up-flow as the vortex begins to form around the wingtip. They have a large negative angle relative to the wing but are generating

upward lift and a small amount of forward thrust. When used differentially as ailerons, the difference in lift produces a roll, and the difference in thrust causes a small

yaw in the same direction. (These birds are pretty clever!)

Initial setting: no roll, slight adverse yaw

Final setting: good roll, slight proverse yaw

TIP FEATHER CONFIGURATIONS

Here, the formers and side sheeting have been added to the

structure.

FLIGHT CHARACTERISTICS

Set the elevator's neutral position so the elevator is

parallel with the stabilizer. If you

are using a computer radio,

program the throttle lever to

control (bias) the two ailerons up

or down together (like flaperons).

Set the tip-aileron neutral position

so that the leading edge of each

aileron is about 1/8 inch below the

wing's leading edge. Add ballast

as necessary to get the CG to the

location shown on the plan. Do

some hand glides in still air to

establish the trim settings.

For slope advocates, this

model is a real floater, as is its

real-life counterpart. Without ballast, it does not

penetrate well but is quite realistic in a fight

destabilizing influence of

the body, heads, beaks and

other lateral areas

forward of the CG.

Artificial vertical fins in

the form of "feet" (ventral

fins) or clear circular discs

near the wingtip, toed-in

about 20 degrees, can be

beneficial for early flights.

The required fin area is

usually quite small (6 to 8

square inches) and can be

reduced or removed as

flight experience increases.

Note: electric motors at

breeze. If you have a computer radio, you can

experiment with the aileron bias setting in flight.

There should be a position that

allows gentle coordinated turns

with the tip ailerons with no

adverse yaw. If you don't have a

computer radio, try adjusting the

aileron bias on successive flights

to find the best setting. (Don't go

too far upward, or aileron control

will disappear completely.) The

model will be considerably lighter

than the real bird, so experiment-

ing with ballast is appropriate.

Your Turkey Vulture model will

not only attract attention from

your fellow modelers, but it will

also likely attract some attention from other soar-

ing birds, such as hawks and ravens.

the front have been tried and are quite

destabilizing. If you intend to try a pro-

peller, use one of the above techniques to

add some vertical fin area.

STRUCTURE

The outer wing panels of a real bird are

extremely light compared with the rest of

the structure (they're just feathers!). Outer

wing panels should be kept as light as

possible to keep roll inertia low. Heavy

wingtips result in unwanted rolling

oscillations. Unusual wing dihedral

patterns (gull, for example) can be

duplicated by using a full-depth balsa spar

and cutting it to the desired dihedral

shape. For thin wings,

glue carbon fiber to

the top and bottom of

the spar for added

strength. Sheeting the

leading edges (top and

bottom, back to the

spar) will provide the

necessary D-tube sec-

tion for torsion

strength. The model's

weight will likely be

considerably less than

that of a real bird,

especially for larger

species, but this differ-

ence is mainly in the

fuselage (body weight

and shoulder muscles).

88 MODEL AIRPLANE NEWS

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