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balance with retracts

Old 03-12-2010, 03:23 PM
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dwreel
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Default balance with retracts

Do we balance a plane with retracts in the up or down position ?

dick.
Old 03-12-2010, 03:26 PM
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MinnFlyer
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Default RE: balance with retracts

Up.

If anything, gear down will make it a little to the nose heavy side (but only a tiny bit) for take off and landing - which is better than flying around slightly tail heavy
Old 03-13-2010, 05:37 AM
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Default RE: balance with retracts

Up as Minn said....but I don't know why....the attach point of the gear is fixed at the pivot point......gear down and gear up are still attached at the same point
Old 03-13-2010, 06:31 AM
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Default RE: balance with retracts

Yes, but as the gear come down, the wheels swing slighty forward - not to mention what a nose wheel does
Old 03-13-2010, 07:34 AM
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Ed Smith
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Default RE: balance with retracts

The attachment point has little to do with the balance. On my P40 the wheels swing back and rotate. I balanced it with the gear down. then I balanced it with the gear up. It was one tail heavy airplane with the gear up. It would have been unflyable. I would suggest the airplane should be balanced in it's flying configuration.

Ed s
Old 03-13-2010, 09:08 AM
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Default RE: balance with retracts


ORIGINAL: jetmech05

Up as Minn said....but I don't know why....the attach point of the gear is fixed at the pivot point......gear down and gear up are still attached at the same point
When the gear is down, the weight of the gear is exerting a downward force on the attachment point. When the gear is up, the weight of the gear is exerting a rotational moment at the attachment point.

Wow, 20+ years since Statics and Dynamics and I managed pulled that out of my butt.
Old 03-13-2010, 09:23 AM
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Default RE: balance with retracts


ORIGINAL: Ed Smith

The attachment point has little to do with the balance. On my P40 the wheels swing back and rotate. I balanced it with the gear down. then I balanced it with the gear up. It was one tail heavy airplane with the gear up. It would have been unflyable. I would suggest the airplane should be balanced in it's flying configuration.

Ed s
I had a friend crash his ewly built P40 because he did not balance the plane with the gear up, he has now learned his leason on that.
Old 03-13-2010, 08:12 PM
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dwreel
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Default RE: balance with retracts

Thanks a bunch everybody. I do apreciate all the responses.

dick.
Old 03-13-2010, 11:31 PM
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Default RE: balance with retracts

Another tip I thought of. When the time to land comes and you drop the gear, if the plane does pitch down dont forget that you can re-trim the plane for level flight at cruise. This way your not fighting the elevator as much on landing. Later, if you like, you could also do a gear-elevator mix.
Cheers.
Old 03-14-2010, 10:46 PM
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Default RE: balance with retracts

Always balance the plane with the gear up and with no fuel. Because P-40s and Corsairs rotate back, the plane really needs to have it balanced with the gear up. Fly the plane up about 200 feet before you retract the gear to see how the plane reacts. If you get in trouble you will still have time to drop the gear.
Old 03-14-2010, 11:28 PM
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Default RE: balance with retracts

Also remember even on gear that retract towards the center the drag will cause the nose to pitch down when they are extended. This will not affect balance but will affect trim in flight.
Old 03-15-2010, 02:43 PM
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Default RE: balance with retracts

[/quote]
I had a friend crash his ewly built P40 because he did not balance the plane with the gear up, he has now learned his leason on that.
[/quote]

How much did the cg move with the gear up compared to where it was with the gear down. Made him crash? He must have had the cg excessively far back to begin with.

Kurt
Old 03-15-2010, 05:43 PM
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Ed Smith
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Default RE: balance with retracts

How much did the cg move with the gear up compared to where it was with the gear down. Made him crash? He must have had the cg excessively far back to begin with
Well not realy. I checked mine in both positions before I flew it. With the gear up it was enough tail heavy that I did not even think of flying it.

A scale airplane even slightly tail heavy is usualy headed for disaster.

Ed S
Old 03-15-2010, 08:24 PM
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Default RE: balance with retracts


ORIGINAL: Bozarth
I had a friend crash his ewly built P40 because he did not balance the plane with the gear up, he has now learned his leason on that.
[/quote]

How much did the cg move with the gear up compared to where it was with the gear down. Made him crash? He must have had the cg excessively far back to begin with.

Kurt

[/quote]
I really don't know, it was a kit built plane, and not his first, he is in his mid 40's and been flying all of his life, so he had some experience, but he has never been the most carefull type flyer, he uses the saying that looks about right a lot.

Jon

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