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Old Oct 25, 2011, 09:33 PM
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KragerÝ, Norway
Joined Jun 2010
732 Posts
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How do you feel that your plane is tailheavy?

Is there any way to "feel" that the plane is tailheavy? My CG is right, but it kinda feels like its a little tail heavy..:P
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Old Oct 25, 2011, 09:40 PM
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United States, NJ, Manchester
Joined May 2011
1,190 Posts
If you put your 2 fingers under the COG of the wings you can tell by that. If you are flying and you let of go of the sticks the plane will try and tilt back to climb. Nose heavy > tail heavy

Balancing it perfectly at CoG is what you want.
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Old Oct 25, 2011, 09:54 PM
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galaxiex's Avatar
Edmonton,Canada Eh
Joined Jun 2007
7,573 Posts
Tail heavy usually flys somewhat to VERY sensitive in pitch axis.

I once put too light a battery in my EZ Star (making it VERY tail heavy) and had about 30 seconds of excitement!

Very difficult to keep the plane level. The tiniest twitch on the elevator had a HUGE effect.
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Old Oct 26, 2011, 03:06 AM
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Birmingham, Alabama
Joined Jun 2002
2,970 Posts
1) experience
2) calculate the CG/MAC
3) age old adage, "nose heavy planes fly fast and poorly (like a brick), tail heavy planes don't fly long"

nose heavy planes:
stall nose down
(in LOS flying) are typically trimmed to fly level at 1/2-WOT, and decend with the AOA decreasing at lower throttle settings

tail heavy planes:
become very sensitive in pitch
can become snap happy at low speeds
when elevator throw is too much at any flying speed, can show a preference to stall one wing & cause a snap

severely tail heavy planes will simply try to backflip as speed decreases





obviously every plane is different, but many standard layout (wing in front, stab in back) mostly straight wing planes balance somewhere around the max thickness of the wing.
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Old Oct 26, 2011, 07:15 AM
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United States, FL, Panama City Beach
Joined Oct 2001
2,680 Posts
How to test for correct COG in flight.

!. Get as close to calculated COG as possible.

2 Fly it and trim elevator for level flight at cruise speed. (NOTE: ALL stabilization/gyros OFF)

3. Climb to sufficient altitude for an approx 2-3 second 45 degree dive.

4. Perform 45 degree dive and watch for plane to steepen the dive or begin to pull out without any stick input.

Results;

Increasing dive as speed rises = Tail-heavy

Steady 45 degree dive no change with speed = Ideal

Pulling out by itself = Nose heavy.

Hope this helps,

Rob
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Old Oct 26, 2011, 08:09 AM
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United States, WI, Eau Claire
Joined May 2011
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Isn't that backwards? A nose-heavy plane will push the nose down, increasing the dive?
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Old Oct 26, 2011, 09:14 AM
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Portugal
Joined Nov 2009
815 Posts
No, it isn't...

In a nose-heavy plane you need to have up trim (elevator) and then when the plane is in a dive this up trim cause it to going up thus recovering...

Quote:
Originally Posted by banzi28 View Post
Isn't that backwards? A nose-heavy plane will push the nose down, increasing the dive?
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Old Oct 26, 2011, 10:39 AM
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United States, WI, Eau Claire
Joined May 2011
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Ah gotcha! Going to try this out! Many thanks!
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