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Old Apr 25, 2005, 02:05 PM
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decalage CG relations

hi there

does anyone know if there is any relation between decalage angles and C of G at a plane?

i am in doubt if we can change the CG with changing the decalage

or it is better i say if i change the decalage angle the CG of my plane must be changed or no?if so,with what decalage and cg i will get best performance with a indoor model (rudder only?)

thanks for any advice
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Old Apr 25, 2005, 02:16 PM
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Palmdale, CA
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There's no direct connection..
The longitudinal dihedral must be adjusted for the plane to fly properly..
With a rudder plane, there will be a lot of l.d. anyway.
Change the c.g., then adjust the l.d. to suit, if you feel it needs it.
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Old Apr 25, 2005, 04:53 PM
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The CG location is the only adjustment that affects stability. Therefore CG location should be used to establish the desired stability and for no other purpose! To set the trimmed flight speed use the elevator trim setting on the transmitter or by adjusting the decalage (angle between the wing and horizontal tail). If the elevator neutral is too far off geometric center, then elevator offset can be replaced by a decalage change to get the elevator neutral closer to geometric center.
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Old Apr 26, 2005, 05:27 AM
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ok thanks for your helps

but how i could find the right decalage for an indoor?(only trial and error?)

any way these angles and lines are compared with a base line(fuse line),i have made a plane that the wing is at higher point than the horizontal tail(with about 4 degrees decalage) but the wing is higher than the horizontal stab(because of the fuse shape) i dont know if this could cause any problem or no
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Old Apr 26, 2005, 07:04 AM
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When a symphony orchestra prepares to perform, just before the performance, it tunes up. This is so the various instruments can harmonize with each other to produce beautiful music.

A pilot, plane, launching device and radio are a system where the parts have to be adjusted to each other in a harmonious way to make beautiful flights. When the parts are not adjusted to each other, do we blame the parts or the adjustor? Often two people will have differing opinions about a particular design of plane because they attribute the differences to the design rather than to differences in the way the otherwise identical planes were adjusted to match the systems they were being flown in.

There is a wrong headed point of view that is running rampant. It is that the way a plane flies is entirely due to the design and to the manufacture. I think of this as the "appliance" mentality. It appeals to a lot of people who only buy ARF's and who expect the plane to perform properly when assembled according to the instructions without any further effort on the part of the owner. These people have generally not informed themselves of the affects of various adjustments. This approach can only result in a relatively safe but mediocre performance.

For best results the CG location has to be adjusted to the pilot's ability and flying style. The decalage has to be adjusted to the CG location and to the pilot's skill and flying style. The thrust line and control throws have to be adjusted to the pilot's flying style. Furthermore the adjustments have to accomodate the flying conditions and the particular purpose of the flight to be made. The adjustments will be different if nonobjective.
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Last edited by Ollie; Apr 26, 2005 at 07:13 AM.
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