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What causes this?

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What causes this?

Post  oldguy on Wed Jun 20, 2018 4:08 pm

https://www.youtube.com/watch?v=ZTGsB1j1aQQ

At the 22 second mark on the video, and again at the 32 sec mark on the video you can see what I guess I would call it, a wobble?  What causes the plane to do this?
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Re: What causes this?

Post  Ken Cook on Wed Jun 20, 2018 8:01 pm

Is this a scratch built designed plane or a kit? Your maneuvers are taking place very quickly and sharply. This is stalling the wing which is causing a loss of air speed and the wobble you see. Open up your maneuvers a bit so that you maintain the speed. Other factors such as plane weight to square wing size come into play. If your on the beefy side in terms of weight, this is causing the engine to work even harder. It's very difficult to diagnose a problem watching a video.

Speed and keeping the speed is critical. When you introduce engine offset and rudder offset, this has the plane flying sideways. This scrubs off needed speed and promotes the wobbling you see in your video. You want the plane to fly tangent to the circle in a non- restrictive manner. Having too much line rake, engine offset, rudder offset, and too much tip weight contributes to the problem your seeing.


Doing consecutive maneuvers back to back is really going to bleed off speed. It looks cool but it really strangles the plane. If the plane is on the heavy side, it needs to fly fast. Thin wing planes suffer the same fate. However, if you enter into a maneuver with full arm extended and using your entire arm will open the maneuver and keep the plane sustaining.
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Re: What causes this?

Post  oldguy on Sun Jun 24, 2018 6:12 pm

Ken Cook wrote:            Is this a scratch built designed plane or a kit? Your maneuvers are taking place very quickly and sharply. This is stalling the wing which is causing a loss of air speed and the wobble you see. Open up your maneuvers a bit so that you maintain the speed. Other factors such as plane weight to square wing size come into play. If your on the beefy side in terms of weight, this is causing the engine to work even harder. It's very difficult to diagnose a problem watching a video.

            Speed and keeping the speed is critical. When you introduce engine offset and rudder offset, this has the plane flying sideways. This scrubs off needed speed and promotes the wobbling you see in your video. You want the plane to fly tangent to the circle in a non- restrictive manner. Having too much line rake, engine offset, rudder offset, and too much tip weight contributes to the problem your seeing.


        Doing consecutive maneuvers back to back is really going to bleed off speed.  It looks cool but it really strangles the plane. If the plane is on the heavy side, it needs to fly fast. Thin wing planes suffer the same fate. However, if you enter into a maneuver with full arm extended and using your entire arm will open the maneuver and keep the plane sustaining.

It is and old scratch built plane, thanks for the info and recommendations.  I just haven't noticed this before on other planes I have built and flown.
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Re: What causes this?

Post  Ken Cook on Sun Jun 24, 2018 8:26 pm

Jim, that was the Fox .15 on there in the video? It certainly sounded like it was no slouch, it was doing pretty good. It did sound a bit lean but it didn't seem to be sagging badly. Very very nice. I do enjoy them and this is a great example when I mention they like to be turned up. Pretty darn cool there. Ken
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Re: What causes this?

Post  getback on Sun Jun 24, 2018 9:10 pm

Man that was crazy it does have a sing to it (love is in the air ) Nice way to hold on , was this the first flight ? The cameraman seem to be a bit close or just my perception . Very Happy COOL !!
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Re: What causes this?

Post  getback on Sun Jun 24, 2018 9:16 pm

May be a little less throw in the controls if it were me . Smile
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Re: What causes this?

Post  oldguy on Sun Jun 24, 2018 11:35 pm

Ken Cook wrote:Jim, that was the Fox .15 on there in the video? It certainly sounded like it was no slouch, it was doing pretty good. It did sound a bit lean but it didn't seem to be sagging badly. Very very nice. I do enjoy them and this is a great example when I mention they like to be turned up. Pretty darn cool there. Ken

Yes ken the old fox .15, that everyone seems to dislike, but I have several planes with these and I have never had an issue with them. I have alittle problem with trying to get everything out of them so yea I sometimes run them a little lean. Yes they like the 7x6 prop.
Thanks
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Re: What causes this?

Post  oldguy on Sun Jun 24, 2018 11:37 pm

getback wrote:Man that was crazy it does have a sing to it (love is in the air ) Nice way to hold on , was this the first flight ? The cameraman seem to be a bit close or just my perception . Very Happy COOL !!

No that was a flight of many on this old plane, it's had it's share of crashes and put back together, can't ya tell by looking at her.
thanks getback.
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Re: What causes this?

Post  oldguy on Sun Jun 24, 2018 11:38 pm

getback wrote:May be a little less throw in the controls if it were me . Smile

I will try that next time I fly it, I will move the control rod up on the horn.
Thanks
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Re: What causes this?

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