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Flap Mixing

Old 06-10-2016, 01:04 AM
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Default Flap Mixing

Hello everybody!

I just got ahold of a World Models GS P51, and I'm just wondering if anyone can shed some light on a good starting point for flap mixes. I only say starting point because I know that what works for one plane is not necessarily going to work the same for another, even if it is the same plane. Specifically:

1: Is down ELEV mixing even necessary on this plane when using flaps?

2: What percentages/deflection of FLAP>ELEV yielded acceptable results?

3: Did you use only the recommended FLAP deflection or did you also use full flaps?

Again, I realize as different CGs are used, and different build preferences are out there, I can only expect a range. BUT, as balance is balance, even an idea of what deflections have yielded favorable results will be a big help. I have flown the plane at the manual's CG, with a touch of nose-heavy, and landed using the manual's recommended FLAP deflection, and it's a lil hot but ok, as expected.

I am using the Spektrum DX9. Right now I have the FLAP on a 3 pole:

0) 0 Deg flap, 0% ELEV
1) -30% flap (50mm), 3% ELEV
2) -60% flap (as much as possible without the flap servos binding--I didn't measure, but it looks to be 45-50 degrees), 5% ELEV

So far have only tried landing with the 1 position. It doesn't dive crazy, but it lands what seems like a little hotter than it could, with seemingly too much down. I'm not sure if this is because of too much elevator OR the way I have the plane balanced. The "full" flap position (2) seems like an awful lot, more brake than lift, gonna try that one way up high and see how she handles. Im going to rebalance it closer to neutral and see if that helps.

In the meantime, any advice based on experience with this airplane would help and be much appreciated!

Thanks in advance!
Old 06-10-2016, 07:01 AM
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For starters my P-51 time was on a GP kit built and I have not flown your model. If I was guessing the kit built probably had a higher wing loading. I tried a few mixes on it and was never happy with the results. I wound up just pulling a flap switch and flying it in. The issue I had with the mixes was more to do with flight conditions I guess. If a mix worked well on a 70 degree calm day. It did not work well on a 90 degree windy day. I still ended up flying the elev I needed. The best I got it was 30 degrees of flap and three clicks above idle and it was pretty easy to fly in.

Sorry I could not be more help, David
Old 06-17-2016, 05:11 PM
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I have used elev mix with flaps on several planes , mostly P51's.

I like it a lot as I don't like to push forward on the elev stick when landing, I can never get it to come in smooth its always roller coaster.

as to the amount, can't say, it was always a trial and error until I got it right. I always wanted the plane to go into a decent with flaps on for landing

if I put a little too much in I just pull back on the elev and extend the landing out.

as said before , I know this is not much help. But it all depends on the plane , wing loading, how you want it to come into a landing.

good luck
sticks
Old 06-17-2016, 05:22 PM
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I had a thought about this in the way of a wave off.

when coming in with full flaps on and low and slow, be carful about a "wave off" . you can't just turn flaps off, and then throttle up, you need some power and more speed before going "around".

I try and set take off flaps about 20 % and when I go around I put power back on slowly, move flaps to the take off position and then more power, then flaps off.

I don't know if this is the best way , as I am just getting into flaps myself this last year or so.

I would like to hear from anyone about this wave off with flaps.

sticks
Old 06-22-2016, 07:31 AM
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Well hear is my 2 pennies worth, A lot depends on the weight : ie wing loading of the bird. Heavy = more flap with power management, light=less flap but still power management.

If it was me I would balance as about 2 deg's noes heavy fly it up hi and throttle back and add flaps see what it does, then adjust to suit
I don't like the dial flap function so I use one of the three position switches ; ie up, take off, and full flaps
Both of my birds T/F G/S Corsair and P-47 are at 30+ lbs full flaps is 45 deg's on both.

One more thing I am not farmiliar with what the full flap angle setting should be for a P-51

Hope this helps

Cheers Bob T
Old 06-22-2016, 05:46 PM
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Originally Posted by rt3232
Well hear is my 2 pennies worth, A lot depends on the weight : ie wing loading of the bird. Heavy = more flap with power management, light=less flap but still power management.

If it was me I would balance as about 2 deg's noes heavy fly it up hi and throttle back and add flaps see what it does, then adjust to suit
I don't like the dial flap function so I use one of the three position switches ; ie up, take off, and full flaps
Both of my birds T/F G/S Corsair and P-47 are at 30+ lbs full flaps is 45 deg's on both.

One more thing I am not farmiliar with what the full flap angle setting should be for a P-51

Hope this helps

Cheers Bob T
my book on the Hanger 9 P51D "blue nose" is take off 7/8 in or 22degrees, landing 1 3/4 in. or 43 degrees. this plane I have not landed and have no idea if this works, just out of the book. This is a larger plane, calls for a 1.20 four cycle. or 20 to 25 cc gas.

my P 51 PTS MKII calls for 1 in. flap landing , and I try and use about 20 degree's for take off. I have two of these .45 glow planes and they come in great with full flaps.

I have had very good luck on the heavy planes with flaps and what I put on this is a general idea. Its just a starting point. Like I said I like to have the plane on a decline with full flaps for landing and that is a personal thing.
If you have a long landing strip, start lower and work up on the landing flaps and mix on elevator.

sticks

Last edited by Stick 40; 06-22-2016 at 05:53 PM.

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