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Old 08-17-2016, 06:30 AM   #1
Flyinbullmax
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Eratic trainer on take off


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Hi, I had to take off a Kadet Mark II and the minute I put throtle the plane starts to trow itself to the right and left wing lifts up before the right one. I tried to keep it on track but nothing to do, I had to abort many times before being able to take of. The wind was across the track left to right.
What could it be. We see that pretty often on a trainer.
Thanks for the advises.

JP
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Old 08-17-2016, 07:18 AM   #2
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Re: Eratic trainer on take off

Looks like you are trying to take off cross wind. Try pointing straight into the wind for take off. With a high wing trainer taking off cross wind will always lift the one side first.
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Old 08-17-2016, 07:55 AM   #3
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Re: Eratic trainer on take off

if it always reacts that way I would use a Robart incidence meter to make sure the outer wings are not warped as this can happen often with built airplanes from kits.
Borrow one from a club member if possible . If one wing has a different incidence that the other that can affect flying.
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Old 08-17-2016, 09:27 AM   #4
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Re: Eratic trainer on take off

You actively have to work to maintain the aircraft while moving, not just in the air. Just like in full size there are techniques to account for when the wind is not directly down the runway, (crosswind take off). Same for landing.

There are also factors built into the airframe that help correct for the twist and turning tendency of the engine/prop combination. That prop forms quite a large gyroscope and definitely has an effect when spun up. The firewall often has a right and down orientation with the engine mounted so the nose is centered in the cowl front to help counteract the pull to the left when applying power on take off and the up or down pitch changes with power.

That left pull on power up is normal, even in calm conditions so you have to stay on top of the rudder control to keep it straight. When the wind is not right down the runway you make the same rudder inputs, just may need more of that and ailerons as well.

Along with the obvious rudder input to keep the aircraft along centerline you input aileron to turn slightly INTO the wind. On the ground this helps keep the wind from trying to flip the plane over, (kwm is right on about high wings suffering more from this effect). It will also help maintain wings level once it leaves the ground.

Only practice and experience will tell you how much you should input, so don't feel discouraged if the plane is ahead of you for a bit. This is where joining a club and finding a good instructor can be such a great help. Don't forget, we all started the same place as you and often that encouragement from someone willing to help along the way made all the difference.

Another advantage is having someone with experience look over your plane for anything that may be incorrectly built, rigged or assembled. This is not only for safety; there may be something wrong that makes flying the craft so much more difficult.

Take the advice about maintaining control throughout the flight, ground ops as well as air. Even a perfectly built airframe requires this and even one that is not built straight may fly, but I can guarantee it will take more work to do so. If early in your flight training you may not have time to input the controls or recognize what has to be trimmed to get it to fly hands off. This trimming is one that is almost always needed on a maiden flight and environmental changes later can require a "Tweak" of trim.

Stegl is correct regarding a warped wing. If not heated correctly while tightening the covering can introduce a twist in the panels. The proper procedure is to alternate shrinking one rib bay top and bottom as you work your way along.

You can often correct for twist by reshrinking the covering while physically introducing an opposite twist a bit beyond where it needs to be.

NOTE: This only applies to heat adhesive/shrink type covering. Even then there can be differences so if you know that info look up the specs for the amount of heat to do a final tightening. I mention that since a few have different tightening temps, (low and high) and actually get pretty loose before snapping taught.

I will add one more item: your control surfaces must be installed and rigged correctly. Just like an airframe not built true having them off can make even a perfectly straight structure difficult or impossible to fly.

ps. Too often I see very quick throttle ups from a standing start and the end results are almost always the same: the plane jumps in the air, snaps to the left and dives into the ground. One thing that I try to teach my students early on is to apply power slowly on take off. This minimizes the effect the prop introduces to make the plane turn to the left and allows the craft to build up speed till the flight controls have enough authority.

Hope that helps.
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Last edited by Cougar429; 08-17-2016 at 09:33 AM.
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Old 08-17-2016, 04:43 PM   #5
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Re: Eratic trainer on take off

I learn't how to fly on a Kadet Mark II. I found I needed a little up elevator in any wind from any direction to stop the dreaded wing drop. It seems the Kadet almost wants to nose over on the ground without the elevator to hold it straight. Cheers Floyd
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Old 08-17-2016, 06:39 PM   #6
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Re: Eratic trainer on take off

That may be the drag from the mains loading the nosewheel. Trikes have the habit of trying to fall either way over the nose, (the same reason Honda 3-wheelers were banned).

Pulling up elevator serves to negate that and with a flat bottom airfoil give it the AoA to lift from the ground.
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Old 08-18-2016, 09:14 AM   #7
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Re: Eratic trainer on take off

Quote:
Originally Posted by Cougar429 View Post
That may be the drag from the mains loading the nosewheel. Trikes have the habit of trying to fall either way over the nose, (the same reason Honda 3-wheelers were banned).

Pulling up elevator serves to negate that and with a flat bottom airfoil give it the AoA to lift from the ground.
I also remember it was better after I put a bigger nose wheel on that changed the angle of attach on the ground into the wind. Cheers Floyd
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Old 08-20-2016, 10:00 AM   #8
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I am almost past the learning stage, and I always found the takeoff mofe difficult than the landing. My trainer would always go to one side. I have to ways to make the takeoff good. First, always make sure you know which way the plane will move (away from you or torward you) when you add right or left rudder. Second, add throttle slowly, that way you have more time to correct, and a small chance to have your engine quit on takeoff.

Hubert
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Old 08-20-2016, 02:58 PM   #9
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Re: Eratic trainer on take off

One thing I neglected to mention was to check your main wheels are straight. If they are not you will have more difficulty in directional control on the ground.

If the main gear is too flexible drag will force them aft and likely give toe out.
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