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Building Tips and technical articles. => Building techniques => Topic started by: Randy Powell on July 09, 2019, 11:52:33 AM
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So, you know how when you have an issues but you tell yourself, I don't need to fix it, I can just work around it? No, well, that's where I was. I made an error in the assembly of this plane and hoped I could trim around it. I couldn't. So, new control surfaces. Should have it back in the air in another week or so. Lot of stinking work for a stupid mistake.
Sigh....
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Didn't leave enough room to allow full deflection. When it turned out that I had to add nose weight, I didn't have enough elevator. I will now
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Looks like a lot of fun...NOT.
What do you use for hinges and how were you able to remove the original control surfaces?
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Randy has a history of flying on one line and snagging things with the slack one. This time he figured it prudent to do the fix before attempting another flight.
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Randy that much deflection is basically an air brake rather than control impute. I don't think in real practice you apply more than 25 degrees of deflection on any surface and anything more than that is not effective. For such drastic deflections you must have some turbulators in front of the hinge-line to keep the airflow attached to the flying surface.
The question is why go through all this where a little tail weight takes care of the turn.
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Randy that much deflection is basically an air brake rather than control impute. I don't think in real practice you apply more than 25 degrees of deflection on any surface and anything more than that is not effective. For such drastic deflections you must have some turbulators in front of the hinge-line to keep the airflow attached to the flying surface.
The question is why go through all this where a little tail weight takes care of the turn.
I, too, am curious how much it moved *before* it was fixed, because the modified version moves a good 10 degrees further than I have on any of my airplanes, and normal trimming doesn't require anything near that much movement.
Presumably, the surfaces were removed by removing the continuous hinge pin, and the new surfaces built around the existing hinge positions.
Brett
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Randy that much deflection is basically an air brake rather than control impute. I don't think in real practice you apply more than 25 degrees of deflection on any surface and anything more than that is not effective. For such drastic deflections you must have some tabulators in front of the hinge-line to keep the airflow attached to the flying surface.
The question is why go through all this where a little tail weight takes care of the turn.
IMHO there is such a thing as using too much control but no such thing as having too much control.
Wasn't the original issue having to add nose weight? I won't let a ship off of my workbench that has less than 40 degrees. Most have 45. It is rare that I need to do a one liner but when I do need it I want it there even if it stalls the plane as long as I can get the nose pointed up for the motor to save the day.
Now having said that if you need more that 25 to turn a decent corner then you are in fact nose heavy, so my question would be why would you want to be nose heavy?
"But, that is just me and I could be wrong."
Ken
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I watched Randy fly at Auburn a few weeks ago and could tell immediately that he had problems. Both the flaps and elevators were hiindged to closely to the wing and stab and could not deflect more than ten to fifteen degrees before hitting their limit. It was an accident loking for a place to happen. Paul and I checked the CG anl luckily Randy took our advice and put the model inthe car with suggestions in hand. Glad to see repair and replacement is progressing. See you north of the border early August Randy..
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Yea, at the Auburn contest, Alan and Paul told me what I already knew. The thing was hinged too closely. Has 12 degrees of deflection. Not enough, obviously. Now has about 38 degrees at full tilt. And no, I doubt I'll use more that 20-25 degrees. And the controls are much more free. Should fix the issue.
An no, it's not nose heavy. It was tail heavy and a bit squirrelly. Added nose weight and the touchiness went away but then it wouldn't turn. So, now it will turn. I hope, anyway.
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Any more progress on the fix?
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Yea, at the Auburn contest, Alan and Paul told me what I already knew. The thing was hinged too closely. Has 12 degrees of deflection. Not enough, obviously. Now has about 38 degrees at full tilt. And no, I doubt I'll use more that 20-25 degrees. And the controls are much more free. Should fix the issue.
An no, it's not nose heavy. It was tail heavy and a bit squirrelly. Added nose weight and the touchiness went away but then it wouldn't turn. So, now it will turn. I hope, anyway.
Randy, since there are multiple ways to correct this issue I am curious (not critical, just curious) why you elected to build a whole new set instead of modifying the originals.
Ken
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Ken,
I felt it easier just to cut the controls off and do it again. I was able to save a bit of weight and get freer movement. The controls are smoother now.
Wayne,
It's basically done. I'm waiting for some clear I ordered to get here. Then it will be done.
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Wayne,
It's basically done. I'm waiting for some clear I ordered to get here. Then it will be done.
Cool, hope it all works out when you get'r in the air.
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Wayne, hope to fly it this weekend if the weather cooperates.