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pulls left
finished my 750 STOL and when I went to take off it flew left. I gave it full right rudder and when I touched down the plane flipped forward and left due to nose gear. Don't know why it fly's left. Checked wings and engine centerline thrust. Maybe gear is misaligned but don't know. My fix may be to install a trim tab on rudder. Any suggestions? Anyone else had this problem?
Dave
Replies to This Discussion
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Permalink Reply by Paul Sanders on
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When I did my first flight Roger told me that if it pulls left to call him and he will tell me the simple solution. Fortunately I didn’t need to but this is a common occurrence and there are posts on here discussing it, if you can find them. Or a call to Zenith will give you the answer.
ok, how about this? Roger show how to fix a heavy wing
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Permalink Reply by John Austin on
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I think it would be unusual for a heavy wing to require full right rudder for correction, especially considering how effective the rudder is!
First simple thing to check is that the rudder deflects in the proper direction with each pedal and that the cables are crossed as per plans. I know of at least one accident where an experienced builder simply forgot to cross the rudder cables! In that scenario, a small amount of right rudder might be inputted for p-factor, the plane turns left due to elevator being reversed, more right rudder, more deviation left and off you go into the weeds ... it happens!
John
N750A
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Permalink Reply by david junkins on
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Thanks John for your input, but I have checked all cables etc. I was also given a fix from Roger at Zenith. He said in a Youtube video to crimp the trailing edge of the 'light' wing. Here is the link: https://www.youtube.com/watch?v=HYhXoUcXTYc&t=10s
I think that is a permanent fix and I could have the same effect with a little weight on the wing instead of crimping it. That would make it easy to adjust for a passenger or future weight change.
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Permalink Reply by Ralph Powell on
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David,
Good video, but suggest having a good st down and really looking at why plane behaves the way it does. Then tape a trim tab on high wing. Trim tab can is simple and non permanent. Just take a piece of spare aluminum about six inches by four, crease long ways and tape it to your high side (new flap sticking-up). The object is to decrease lift. Try it, pull tape off bend it some more or try it somewhere else. There are is a lot of good info and tips on this forum, read them. A slightly heavy wing is one thing, full rudder??? I agree with John, unusual. Suspect something in controls needs more adjustment. Or maybe a couple of controls are off a little.
Ralph
N750RP
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Paul: Good idea with the trim tab. I think that is better than adding weight. Don't know who to 'sit down' with. Can't get a response from Zenith. This builders blog is the best I have found. I think I will try your idea first and slowly lift nose wheel off to see what happens. Then go from there. Thanks Paul.
Dave
<'(((>/p>
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Permalink Reply by Jonathan Fay on
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Zenith was at KOSH all week, they should be back in office later, but they have always been great. Talk to Roger for sure about it. Video from over your shoulder and EFIS data dumps are indispensable in debriefing yourself after flights. What you remember and what happens can often vary dramatically. Video is not about just YouTube selfies, its a powerful tool to be able to fly the plane in the moment, and then learn after the fact in detail what really was going on.
On a high speed taxi the day before what was supposed to be my first flight, I got surprised by a sudden pull to the left that pulled me into the grass on the side of the runway. I put takeoff power in too quickly before I had enough speed for rudder authority, and was using the nose wheel to keep the center line, when the nose wheel went up, so did the p-factor, and if the nose was straight for the nose wheel on the runway, it was not actually countering the left turning tendencies from the aircraft the instant it was in the air, so only instant full rudder would have helped, but human reaction is too slow at that point, your have to be ready for it before you need it. In the moment it seem unexpected and uncontrollable, but with time I found out there was nothing wrong, I just needed to know the airplane and be in front of its needs.
I did transition training but that had been a while. If you transitioned from a 172, you can not treat a 750 like a 172 or your will be in trouble. Especially important when you start stalls, DO NOT put power back in until your nose is down and the wing is flying again, or again, you will find the plane rolling left and going all the way upside down, then pointing down and you will have to execute a spin recovery.
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Ralph: Where did you put the tab? inboard, middle, or outboard of aileron?
Dave
<'(((>/p>
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Ralph: I forgot to ask. Can you give me a wild guess on what tab angle to start with?
Dave
<'(((>/p>
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Object is to destroy lift. Tab points up. Not brain surgery. I used Gorilla duct tape to hold tab on. My tab likely only stuck out about 2 inches past trailing edge of wing. Six to eight inches long. Angle? Try 45 degrees, don't like results, bend it again. I suspect that the closer to the wing tip, the more impact it will have. I moved mine all around. A lot of RV's have tabs on their rudders. I tried tab on rudder and noticed that different speeds, different results.
What I discovered is that everything impacts how a 750 flies. One tank is heavy, it flies wing low. Passenger impacts take-off and level flight. Big passenger, descends like a rock rock to the runway..the more hours I flew, the less concerned I became with needing a trim tab since conditions were never the same.
Looking back I think that checking for perfectly level and straight flight is something that should be on your test plan about 20 or 30 hours down. Before that a new pilot needs to be learning the 750. For instance, pull back a little to firmly on stick on take-off and the hold on! I tried a short take-off before I had enough experience in the 750 and I found myself 30 feet right of the runway, nose up and wobbling! Could not give it enough left rudder! My suggestion is just fly it off the runway and let the nose come up when it wants to.
Feel free to give me a call if you want,
Ralph
208 680-2561
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Thank you very much Ralph. This certainly gives me more helpful information to use. As mentioned before in the blog I plan to do what you say and gradually put in power, and gradually allow plane to fly off holding it steady. The p-factor will drop off a little after the plane is airborne and power is steady.
Dave
<'(((>/p>
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What engine and power setting did you have? How quickly did you roll the power in? Was in a roll or a yaw? When did you notice the Left? When the nose wheel came up? How fast were you going?
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OMG Jonathan! That is exactly what happened to me. You and I are mono-e-mono on first flight. I watched Roger on Youtube and he said to just hold the stick back and let the plane fly off. I did that and also put in full power. Surprise! The plane jumped up like a banshee and before I knew what was happening I was airborne and flying left. Too quick to realize if it was rolling or yawing, I think both. As I reduced power and the plane came down the nose wheel was cocked right and the plane pitched forward and down left. I was only 5-10 feet but the shock and awe of it caused a quick reaction without thinking. I was only going 15-20 MPH. That was the first 'flight'. Next day after washing my pants I returned for another try. This time with gradual power and full back stick, as soon as the nose came off (4 different times) the plane pulled left. Third try, yesterday I tried again but tried to lift the mains off. Not much better result there either. Thank you so much for your input. Your advice and experience helps much.
Dave
<'(((>/p>
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