Last summer I put a Tower Hobbies 40-size trainer on floats. The floats are 36" foam core floats that I got from Seaplanessupply.com

When I am taking off after it gets into the air it will drop a wing and make for a very hairy experience. But once I get it up in the air it flys perfect.

Could this be caused by the engine (which is an Evolution .46NX) not having enough right thrust or down thrust?

The CG is where it should be, the step is just behind the CG, the floats are perpidicular, the float tips are about 3 inches forward of the prop, and everything looks correct.

Thanks for any input, Josh

If it is the left wing dropping, you are probably lifting off before you have sufficient airspeed.

Try letting it get more speed on the water before rotating

I can't remember anymore which wing was dropping but after looking at the plane just now it has no right thrust and maybe even a little left thrust.

The reason I don't think the problem is with the airspeed is because on the first couple of flights it took off just fine. But after those first flights the engine bolts became loose and when I went to tighten them I must have not paid any attention to how the engine was positioned.

I guess what I am curious about is what effects does having the engine angled to the right or left or up and down have on the flight characteristics?

If there weren't a thick layer of ice and snow on all the lakes in MN I would reposition the engine and go try it but unfortunately I have a lot of time to think about it.

Josh

When you take off, you should not need much more than a very small movement of the elevator stick. If you are horsing it off with a big yank on the elevator, it can bite you.

Misalligned engine can make things bad. Since I assume you are taking off away from you, you should be able to see if the plane yaws left. If so, a little right rudder pressure will help. Then re-position the engine in the mount with more right thrust and see if that fixes it. You'll probably need to adjust the throttle cable when you do this.

Seaplane supply floats should be fine, and almost any trainer has plenty of vertical stab to be able to carry floats stably.

One last thing: double-check to see that the floats are parallel to each other and to the centerline of the airplane.

I know how you feel! I may work out of my company's Florida office next winter!

I am not forcing it into the air by giving it too much elevator. The reason I believe this is because my first three takoffs were perfect then after that they all went to heck.

After the plane leaves the water it rolls and needs a lot of aileron to get it back straight. Would having the engine slightly angled to the left do this?

I does make sense, to me anyways, that not having right thrust when taking off would cause the plane to roll. Because the engine is making the must torque and the plane is still going relatively slow.

Thanks for the help, Josh

It's very possible. The thrust should be straight, or about 2 degrees to the right (From the cockpit view)

Can you go back to step 1? That is, remove the floats and put wheels back on and see how the planes acts. If the trouble goes away, the problem is in the float instalation. If it remains, it's with the plane itself. Perhaps with the engine instalation. The engine should not have left thrust. I'm not sure what you mean that the floats are perpendicular. They should be parallel to each other and have a slight negative incedence to the plane. That is, the float tips should be slightly lower that the tails, but only a degree or two.
Paul

Not true.

It's much more possible that the problem only shows up with the extra weight and drag of the floats added

42etus: The floats are parallel not perpendicular. My mistake. If they were perpendicular I would have serious issues. Also I did have about 2 degrees of incidence between the wing and floats.

Over Christmas break my family went to Phoenix, AZ and we flew it on wheels. The plane did not experience the same issues as it did on floats. But as MinnFlyer said the floats added weight will magnify the problem.

Thanks, Josh

Well, if the plane was fine on wheels and the take off issue returned when the floats were put back on, the problem is with the floats. It sounds like you have them set up correctly, incidence, CG,
parallel etc. About the only thing left is weight. Foam core floats will add a fair amount of weight and will require a higher take off speed. I have one plane that has foam floats (an Ultrastick 60) and the difference taking it off with wheels compared to floats is very noticable. It needs quite a bit more speed on water to lift off. All my float planes will lift off with just a touch of elevator. If you have to give it a lot of elevator to lift off, you either don't have the incidence right or the plane doesn't have enough speed yet. You said initially that it drops a wing after lift off. That is a classic example of a plane lifting off before it has enough speed to really fly. Try keeping it on the water a little longer to allow it to get more speed up. When it has reached sufficient speed, it should lift off with either no elevator or perhaps just a touch.
Paul

42etus: With the floats on the plane it increases the wing loading. With a higher wing loading the plane could very well experience different side effects.

I have checked the incidence of the floats, made sure there parallel, made sure they are centered with the fuse, put the step just behind the CG, checked the CG of the plane, and even took the rubber band off the water rudder to make sure it wasn't catching when it took off. I have checked it all so I am confident the problem is not float related unless someone can suggest something else to check.

Last night I adjusted the engine and it now has about 2.5 degrees of right-thrust.

The reason why I believe I have enough speed is because I took off three times and it took off straight as a string. Then after those three flights the engine bolts became loose so I took them off to put loc-tite on them. My thinking is that for the first three flights I got lucky and the engine had right thrust but then after I put loc-tite on them I wasn't paying attention and it had a little bit of left thrust.

So now becomes the long wait until the thick layer of ice melts from the lakes so I can give it another go.

Josh,

I still think it's the motor alignment. A straight-ahead motor makes the plane turn left. You need right thrust, and most trainers have about 5 degrees right.
ARF trainers like this one have a clamp-type motor mount that lets you re-aim the motor in a few seconds. It'll take longer to double-check and possibly readjust the throttle than it does to tweak motor alignment.

A buddy of mine has a plane that acts squirrely at full power. He has wash-in in one wing. It can be trimmed for flight, but if you change the throttle setting the trim changes. Makes for hairy takeoffs.

This whole thing is getting more complicated than it should be. It sounds like you've got the floats set up correctly and your engine thrust is at least in the ball park. If you get a good snow fall of soft snow, go out and give her a try. The floats will work fine on soft snow. Don't try them on hard crusty snow, it'll just tear them up. Pay close attention to how easily the plane wants to lift off. It should act like it just wants to lift on it's own. Let us know how it goes.

I am supprised that the Tower Hobbies trainer does not have any right thrust built into the firewall.

Getting 2.5 degrees of right thrust was harder than it should of been because the engine mount is narrow and I had to file it down a little bit in order for the engine to be angled.

5 degrees seems like a lot. I will see how 2.5 goes and if it only improves a little then I will increase it.

The problem with going on the snow is that there are so many tracks from snowmobiles, skiers, vehicles, and who knows what else.

Josh,

It's always a battle it seems. We don't have a gate on our field and once the snow starts, the snowmobilers love to make tracks everywhere. It's just something you live with. Usually it's not a big problem, you just avoid the tracks the best you can. Snow flying is just the ticket to keep flying after the lakes freeze in the winter until they thaw in the spring.

You know what I do to test fly my plane on the ice? Find the lake with the largest expanse of brackish water that no ice fisherman would be caught dead on (I'm thinking of the lakes around Centerville), and find a nice back bay there where the snow hasn't been touched. The good thing about those lakes up there, they are surrounded by reeds hundreds of yards deep, so you have a lot of clear fly over area. Woth the snow coming down today, I think you should be able to do your test flights once the snow stops falling.
Good luck.
Curtis
P.S. My curiosity was with the incidence. You checked this several times, and I assume you took it from the top of the floats to the thrustline of the airplane (not the bottom, or the wing saddle). Best of luck, these problems are not fun.

Looking at this objectively, if a wing drops after takeoff, one wing is generating more lift than the other..

Since there is lots of time to check things this time of year, run an incidence meter along each wing from root to tip. It is not unusual for a wing to develop a twist along its length especially in a moisture rich environment. Also check the elevator and stab, as well as the fin and rudder for twists.
Secondly, check the side to side balance. If one wing drops during a static balance, add weight to the opposite wing tip until the wings are level.

The third thing cant be checked until flying season arrives. If a yaw/turn is allowed to develop at low airspeed (ie right after lift off). the wing towards the center of the turn will be flying slower and thus develop less lift than the wing on the outside of the turn. This causes a roll towards the lower wing. The correct technique at low airspeeds is to level the wings with the rudder (opposite rudder) not ailerons. Using ailerons to correct a wing drop at low speed usually results in a "roll of death" Ailerons make the the situation worse, (the roll continues into the dropping wing) and this has been the demise of many models over the years.

Having 3 or even 300 good takeoffs in a row is no guarantee that the next one (or few) will be as perfect. Something could have crept in to change the equation, and sometimes it is the eye-to-stick interface!

Good luck figuring out your problem...you are getting lots of good advice here.

Better yet... Stay home and keep warm till spring!

When I checked the incidence I actually did calculate the incidence that the flat bottom wing already has. I don't remember exactly what it was but I did take that into consideration.

I am going to check the lateral balance of the plane before I fly it again.

Wayne22: Instead of using a incidence meter through out the whole wing could I just lay each side of the wing on a flat surface to see if it is warped?

I don't know if I feel up to flying it from the snow. I would hate to wreak the bottoms of the floats.

Thanks, Josh

Josh, if you come to the TCRC Auction next month, bring it with you and I'll look it over for you

Now that is a kind offer.....!

Don't trust him he will say, "well I have to take this to my house for full testing, I will check it out and bring it back to you next year'

You could also bring it to the annual spring tcrc float fly in May?

Jon

Jon, you have one of those in May too?

Count me in!

They ahve the float fly 2 times a year, before the park opens and after the beach closes, I did not see it in the listing yet, but I am about 90% sure that it is in the beginning of May.