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taking off advice

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Old 10-17-2005, 12:57 AM
  #1  
Rogerbeep
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Default taking off advice

I am having a lot of trouble taking off. I fly a Kadet LT 40 with a super tigre 51 turning 11/7 prop. I have just learned to fly by my self and my landing are really good but my take off is really bad. My club has a 40ft wide runway and I use all of it taking off. I can not hold the plane straight. My instructor says to get rolling and then go full power. I can roll all day with no problem but when full power hits, its like a drunk preacher trying to walk. I get took off but its as dangerous as it gets the way I see it and I dont know what Im doing wrong. The way i see it if I dont know, then I cant fix it. MY instructior offers no advice. He just says lay with it. Is it the full power thats making it go crazy? Ive straighten the nose wheel perfectly, no help. I changed the pushrod location in the servo to the nearest hole and no help. What is up? Can some one offer sound advice. How fast do I really need to be to take off. Remember I just soloed so Im no expert. Thanks Roger
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Old 10-17-2005, 02:02 AM
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swasey1982
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Default RE: taking off advice

hello there, two things, maybe your steering is too sensitive, another thing is try to be smooth on the rudder, do not over steer, torque is not a big issue on this type of plane, well you dont need to go really fast to take off, 20-30 ft is alot.
also check the incidence on your engine, to which side does it pull first.?

Richard
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Old 10-17-2005, 07:17 AM
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Default RE: taking off advice

You want as little movement in the front wheel as possible. At the servo end attach the linkage on the inside hole on the servo arm and on the wheel attach the linkage to the hole farthest out.

Try not to oversteer and dont punch it to take off. Its better to gradually add throttle and compensate right for engine torque. If the plane flies true in the air I dont think an incidence problem would only show up on take off.

Take off slower with a gradual increase in speed and make small corrections. You probably only need half throttle or so to take off a trainer.

Do other people have the same problem when taking off? Get your instructor to take it off and that way you can see if it is you or the plane.
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Old 10-17-2005, 07:42 AM
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Default RE: taking off advice

All good thoughts. Make the steering as slow moving as possible. Ease in the power rather than punching it. Be prepared to give a little right rudder as needed until you get up enough speed to lift off.

Additional note-the ST 51 is on the strong side for an LT 40. They will fly decently on an LA 40. Try a lower pitch prop. An 11-5 for instance. An 11-4 is too light for the ST. But a 12-4 or 12-5, even a 13-4 or -5, may be about right. The ST is torquey and may like a larger, flatter pitch prop. Can't guarantee it, but I suspect it might easier to deal with using a different prop. Props make a lot more difference than most folks realize. I suspect the 11-7 is causing some of your problem. You might like the way it flies, too. Try that and let us know. I'll be interested in your thoughts.
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Old 10-17-2005, 09:28 AM
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Default RE: taking off advice

I agree....I definitely think you need to ease into the throttle a lot more. Sounds like you're punching it and the torque is getting out of whack, then you're probably over-correcting that, and that's what is making your takeoffs so hairy.
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Old 10-17-2005, 12:44 PM
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Default RE: taking off advice

are you holding a little up elevater to get the plane off the nose wheel and on the mains as you apply throttle?you want just a bit of up elevater not enough to make the plane take off prematurely but just enough to get the nose wheel up off the ground so that you are using the rudder to ster.how much rudder travel to you have?this is the oposite of a tail dragger but the end result is the same,on a tail dragger you give a tad of down to get the tail up and off the tail wheel and use rudder for corrections.try a 11-6 prop as suggested above.
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Old 10-17-2005, 02:24 PM
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nickj
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Default RE: taking off advice

Biggest problem I've seen with a trike gear is a nosewheel not lined up with the rudder. At low speeds the nosewheel does the turning, as you advance the power the rudder takes over. If the nosegear and rudder aren't both pointing in the same direction, it'll be hard to keep the plane under control--you'll tend to overcorrect. Not as big a deal on landings because it's slowing down, so it doesn't wander as far. But definitely a problem on take-offs.
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Old 10-17-2005, 02:34 PM
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Default RE: taking off advice

Biggest problem I've seen is overcorrecting. This is fairly common with beginners. I used to do it all the time. Just make small adjustments on the stick, and you should start to solve the issue. It just takes practice. Of course, you could have a clevise, or steering arm loose, but I would imagine it's probably pilot related. You can practice without the wing on--just practice runs. Be careful, though, not to run it off the end of the runway and tear it up.

When you are ready to do it for real, just ease into the throttle, and let the plane start to lift on it's own. Don't touch the elevator until the plane is ready to fly. It will become light on the wheels, and you'll know it's ready for rotation. Then, rotate it slight nose high, and watch it climb out like a champ!

Something else you might check for is a tight main wheel. Sometimes you get one wheel collar tighter than the other, and the plane will try and do circles around the tight wheel. Make sure both spin freely! Other than that, just practice!
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Old 10-17-2005, 02:35 PM
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Default RE: taking off advice

It may not be you. It may be the plane. Have experinced member of you club fly a couple of take-offs to be sure there is no problem with the plane. If the plane turns out OK, ask him to help you get it down.
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Old 10-17-2005, 07:28 PM
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Default RE: taking off advice

hey guys thanks for the advice. Its all gold to me! Lots of great suggestions and I will try every one because eveybody at the field brags on how slick my landings are for a beginner, but when the see me take off the brags turn into a gut renching laugh, so you see my delima. One of you mentioned having my instructor take off for me and watch him and I do but my instructor instead of taking off the way I do down the runway, he takes off across the runwaywhich is at best only 40 feet. It kinda makes me wonder they built a 500 ft runway?Since I have got all this good advise I have just relocated my pushrod on my servo, it was in the far outside hole,I checked the alignment of the nose wheel, it was ok and I checked all the wheel colars, one was a little different but now there all same. I dont have a bigger prop to try but if what I have done doesnt change things off to the proptoligist i go. Some one mentioned engine angle, frankly thats over my head. The plane flys great when I get it off the ground. And someone mentioned tork, This little motor has buckets of tork so I will not go full power to see if that helps. Again thanks for all the good suggestions. If any one has an idea that hasnt been mentioned by all means let me know. Because my drunk preacher takeoff is not pretty.
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Old 10-18-2005, 12:32 AM
  #11  
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Default RE: taking off advice

Here is one that has not been mentioned (I think). Is the nosewheel pushrod flexing too much? If the pushrod is flexing inside the fuselage, it can allow the wheel to turn when you don't want it to. Most trainers have the pushrod inside a plastic tube, so glue a piece of wood between the inside wall and the plastic tube about 2 or 3 inches from the servo. Be careful you don't get glue on the metal rod. Make sure it can still slide freely.

Something else occurs to me. I have seen planes that were wild on takeoff because the nose of the plane sets higher than the tail. As the plane accelerates down the runway, the tail will lift first. This has the effect of the plane rolling on just the nosewheel before it has quite enough lift to fly. With only one wheel on the ground, the plane can weave around quite a bit. For this, you can try bending the main gear down a bit (assuming they are the standard wire gear), or put larger main wheels on, or a smaller nose wheel.

If none of these works, it may just require more practice as has been said. Make your instructor takeoff the right way- so you can see if it's the plane, or just you. Across the runway, that's cheating!
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Old 10-18-2005, 01:50 PM
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Default RE: taking off advice

I agree with sbd-5, hold a little back stick.

Turn your radio on and look at the elevator. With that size engine in your trainer, I'll bet you have some down elevator trimmed in to keep the plane from climbing at altitude. If you do, here's what's happening.

As your plane gains speed, the down elevator tried to raise the tail, forcing down on the nose gear. There is always some slop in the linkage, the strut and the flew in the wheel. As you put in rudder, the gear tends to flop or lean to one side. When you correct, it leans to the other side, giving you the zig-zag motion.

You want to get the weight off the nose gear and let the rudder steer the plane. Your plane ought to take off in about 20 feet. Hold in about half, 1/2, up elevator and add power. There is a tendency to move both hands forward when you add power, releasing the up elevator, so be careful. Once you gain speed, the nose will come up and in another few feet, you'll be airborne.

In addition, don't hold in rudder, blip it for corrections.

If you are flying at full power or near to it, try 2 popsicle sticks under the trailing edge of the wing. This will allow you to reduce the down elevator needed to hold level flight without climbing. You would like to raise the trailing edge enough so your elevator trim is level at the power setting you normally use.
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Old 10-18-2005, 02:08 PM
  #13  
nickj
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Default RE: taking off advice

Ed, I'm curious about your statement, "don't hold in rudder, blip it for corrections." I usually have to hold in right rudder when taking off any of my planes. I don't think I could control it with blips. I'm wondering how others do it.
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Old 10-18-2005, 02:11 PM
  #14  
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Default RE: taking off advice

How much flex is in your nose gear? I had a newbie in our club who had a trainer with a long spindly nose gear that gave even the most experienced fliers fits when they tried to take it off. If the above suggestions don't work, you might consider replacing the nose gear with something stiffer.
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Old 10-18-2005, 02:37 PM
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Default RE: taking off advice

Boy this is a frustrating thread to read through.

I’ve been teaching folks to fly almost exclusively on Kadet LT 40s for over 6 years now. NEVER had one that was squirrelly on take off OR took a whole runway to take off from.

Torque on a LT 40, regardless of engine size is not a problem. Yes, I’ve even taught on ones that had ST .91’s up front, they all fly the same. Yawing to the right due to P factor is just not a problem with that huge fin and rudder.

First, as the earlier post said make sure the rudder and nose wheel are doing the same thing. If it’s flying straight in flight then it should roll strait on landing WITHOUT you having to correct for it. If not leave the rudder alone and adjust the nose wheel linkages till it rolls straight too.

And as an earlier post mentioned you want to do what full-scale pilots call a soft field take off. Long before flying speed you’re going to lift the nose wheel off the ground and steer with only the rudder while you’re on the ground.

To do this; park the airplane out on the runway at idle, pointing into the wind.

Hold ½ to 1/3 UP elevator on your stick.

Go to FULL throttle on a three count, at a normal pace count one…two…three while advancing the throttle. You should hit full throttle at the end of three. Why do this? I don’t recommend partial throttle takeoffs because it introduces a lot of variables in what is happening. I’ve seen low powered Kadets just barely wallow into the air, on the verge of crashing because the student stopped pushing up the throttle too soon. Also if an engine is going to quit it will do it during throttle up so lets get past this problem too by being at full throttle. Thirdly the airplane will always handle the same at full throttle, partial throttle settings may not be the same on every flight.

Let the airplane accelerate until the nose wheel lifts off the runway or is just visible over the top of the grass. Now adjust your elevator input to hold the wheel there.

We now have the airplane at a positive angle of attack, rolling along on just the mains, accelerating to lift off speed.

Gently steer with the rudder as needed.

In less than 4 seconds the plane will lift off. You will need to reduce the amount of up elevator you are holding so that the airplane holds the same climb out angle that it had in the grass. Usually if you hold the amount that gets the nose wheel up, it will be too much after you lift off resulting in a very steep climb, possibly a stall.

All this takes about 7 seconds and no more than 100 feet even in grass.

HTH


Tom

Oh one last though are the main wheels still pointed straight ahead? If not gently rebend the main gear wires so that they are.
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Old 10-18-2005, 07:46 PM
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Default RE: taking off advice

Rogerbeep-

I have the same problem that you do. I have a Hobbieco Superstar 40 with an OS .46 AX engine. The prop is 11-7. The responce here to your post has been excellent. I need to read these posts over and really digest what has been said here. I can keep the plane up and land it. I thought the hard part was over, but this take off business has really been a problem. You may want to check out a post that I started 9-3-05 at this same forum on the same subject. Excellent information there also.

Good luck. Some day we will get it and wonder why we had such a hard time with it.

Poppy2
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Old 10-19-2005, 01:30 AM
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Default RE: taking off advice

Try adding some toe in on the main gear
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Old 10-19-2005, 03:14 AM
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Default RE: taking off advice

Rogerbeep,

You have received lots of good advice. The posts have touched on all the issues involved with a tricycle gear. Here are some clarifications and perspective on all this:

Yes, the gear should be straight and sturdy and free rolling and not over steer and not do weird stuff, but it doesn't have to be perfect. This stuff is less important. The big issue is the “pressure” of the nose wheel on the ground, especially as speed increases. High pressure magnifies any and all imperfections with the gears. Long story short, the result of excessive nose wheel pressure is that steering at high speed can easily become impossible. This is because of the physics of the tricycle gear arrangement, well described in many books. Basically tail draggers want to “ground loop” (swap ends) and tricycle gear do not – as long as the nose wheel pressure is kept light or off the ground completely! If the nose wheel is on the ground hard, the plane wants to ground loop around the nose wheel dramatically.

3 things control the nose wheel pressure:

1. How far the mains are located behind the CG. Farther back shifts more weight onto the nose wheel. Since you have a very well proven design, the mains are in a good place (unless you modified the position). And since it flies well otherwise, your CG is in a good spot too.

2. The height of your nose strut compared to the mains effects nose wheel pressure. This is easy to mess up. The plane should sit nearly level on all 3 wheels. If yours does not, either shorten the nose strut or raise the mains. Often the mains become splayed out over time and the tail starts sitting low. Bend them back down as needed. A plane that sits "nose to the sky" can lift the mains off first. Rolling on the nose wheel only is very unstable. This condition is called "wheel-barrowing" and is very dangerous. Even if the mains stay in contact with the ground, there is excessive pressure on the nose wheel.

3. Last is elevator control technique. Obviously down elevator forces the nose wheel onto the ground and up elevator lifts it off. So elevator positioning controls nose wheel pressure, which in turn affects directional control. A skilled pilot will use the elevator to adjust nose pressure and therefore steering sensitivity throughout the takeoff acceleration. For your Kadet, just hold about ¼ to ½ back stick and bring in the power smoothly. The plane will lift off on its own when speed is right. Remember to let off of the up elevator as necessary to enter a smooth climb. Keep the nose wheel light but don’t enter a loop after liftoff.

To summarize: adjust your gear heights properly, hold enough up elevator to keep the weight on the mains, and the plane will steer fine. Just that simple.

On landing you aren’t having a problem because you are flaring the elevator back (nose up) prior to touchdown and holding it back after touchdown (keeping the nose light). I know you are doing this because you are getting complements on your landings.

Try landing your plane extra fast (don’t flair as much before touching down) then shove full down elevator immediately after touchdown. This landing roll out will look a lot like the takeoffs you are complaining about.

Multiflyer
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Old 10-19-2005, 06:30 PM
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Default RE: taking off advice

i am actually supprised that you are having trouble taking off because i put that motor on an avistar and all i have to do is give it a little right aileron punch it, and pull the stick back and it goes verticle. i am running a 10x8 prop and have tried all the props in the range and its my personal favorite, maybe a little more throws in the elevator?
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Old 10-20-2005, 11:17 AM
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Default RE: taking off advice


ORIGINAL: skater_719

all i have to do is give it a little right aileron
Right aileron??[sm=spinnyeyes.gif]
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Old 10-20-2005, 01:15 PM
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2slow2matter
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Default RE: taking off advice

Yea, I caught that too!
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Old 10-21-2005, 04:24 AM
  #22  
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Default RE: taking off advice


ORIGINAL: Rogerbeep

I am having a lot of trouble taking off. I fly a Kadet LT 40 with a super tigre 51 turning 11/7 prop. I have just learned to fly by my self and my landing are really good but my take off is really bad. My club has a 40ft wide runway and I use all of it taking off. I can not hold the plane straight. My instructor says to get rolling and then go full power. I can roll all day with no problem but when full power hits, its like a drunk preacher trying to walk. I get took off but its as dangerous as it gets the way I see it and I dont know what Im doing wrong. The way i see it if I dont know, then I cant fix it. MY instructior offers no advice. He just says lay with it. Is it the full power thats making it go crazy? Ive straighten the nose wheel perfectly, no help. I changed the pushrod location in the servo to the nearest hole and no help. What is up? Can some one offer sound advice. How fast do I really need to be to take off. Remember I just soloed so Im no expert. Thanks Roger

on my transmitter i can adjust the servo range cane u do that(i have a futarba 6exa).
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Old 10-21-2005, 07:42 AM
  #23  
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Default RE: taking off advice

As stated above, I have the same hard time taking off. I am still on the buddy box. This post has a wealth of information. Yesterday I went to the field along with the instructor with me, an although all my take offs were not perfect, I did get some really good one off the ground. My control of the plane improved 100%. This is what I did. 1. The nose of my plane was very nose high. I have a Hobbieco Super Star 40 with an OS .46 AX engine. It has wire for the main wheels. I put a wheel collar on the wire, about 3 inches down from the fuse on each side. Then I ran a strong wire across and pulled the wheels in and tighten it in place. This brought the tail up anf made the nose go down thereby making the plane level. It also added extra support to the wheels. 2. When taking off, I tryed as best I could not to over compensate keeping it straight. 3. I kept a little up elevator the entire time it was rolling to keep most of the pressure on the main wheels. These three things improved my take off 100%. Again, I think this post has a lot of good information. When you are learning to fly, you need all the help you can get.

Poppy2
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Old 10-21-2005, 07:44 AM
  #24  
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Default RE: taking off advice

Nick,

You have a Super Tigre .51/11-7 in a Kadet LT 40. Good lord, how can you be on the ground long enough to put in more than a blip or 2 or rudder. You should be airborne in 20 feet or less. Heck, with that power in a trainer, you should be able to hand launch vertical. Maybe your problem is you are playing RC car rather than getting airborne. Hold half back elevator, go to full power, give it a blip or right rudder and you ought to be in the air.

I have been teaching flying since 1971 and I have seem more people damage airplanes trying for a long 100'-200' take off roll with an infinitely slow addition of power. I have never understood this deisre to add power slowly. I didn't in a full scale and I don't with an RC plane except for a rare tail dragger, usually scale, with the gear to the rear that noses over on fast power application. My feeling is you want to get the weight off the wheel, tail or nose. I held back stick on a full scale and the nose came up , then the plane lifted off. I hold back stick on an RC plane and the nose comes up and the plane lifts off. Once you get enough airspeed for the rudder to work, the plane normally straightens out. It's the darn wheels that cause the wiggles, zig-zags, etc.
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Old 10-21-2005, 02:12 PM
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Default RE: taking off advice

Everyone to their own but I think 20' take off's look like JERKOFF's, they sure aren't real. ENJOY !!! RED
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