Take-off problems
 

Hi, I tried to take off my LT-40 from the water yesterday, and was not able to do it. My plane is the one from the previous post called "Will it fly? (LT-40 on floats). The conditions on Utah lake were not exactly perfect because there were waves about 2-3 inches high. My plane is probably a little under powered because it weighs 9.5 lbs. and it only has a .46 AX. Anyway, it went something like this. when I put the plane in the water from the boat, I was surprised to find that it wasn't very manuverable, even with a water rudder I had a hard time getting it to turn especialy when I tried to turn it perpendicular to the wind. When I started to speed up, I was getting alot of water flying through the prop. And just as it was about to take off, the right wing diped down into the water so I cut the engine trying to avoid crashing it. I wasn't able to experement with it much because we didn't have time before we had to leave.
I had a guy at our club that suggested using a .60 and was willing to trade me one for my .46. Do you think I should go for the .60, or should I try it with the .46 a few more times? I'm also clueless about why the right wing dropped like that, I've checked that my floats are parallel, and they are also very even with eachother. Do you think the reason for my handling problems and take off problems could be due to the choppy water? Any advice would be great.

Thanks,

LT-40

RE: Take-off problems
 

A .46 on a 9.5 # plane is too under powered. Yes, a 61 is a good choice. The .46 lacked the power to overcome the wind resistance on the tail section and that is why you had problem turning into the wind. However, if the wind is strong enough, a bigger engine may not have helped. The wing dipped as you were in a cross wind and the wind was trying to flip your plane. When taking off in a cross wind, if you have to, use the ailerons to dip the windward side, the wing that the wind is blowing from. In other words the windward side will dip instead of rising which can then flip the plane over. Full scale pilots also do he same.

I regularly fly my float planes on windy days and have to watch the tip overs. On my 10 lb Cessna, I use a .91 4 stroke. Others flying the same model had good luck with .61 2 cycles so you should do fine with a .61 also.

RE: Take-off problems
 

Make sure that you have 1 to 1 1/2 degrees of positive incidence of the wing relative to the floats, oterwise you may never get it off the water. Also, have the step of the float at the CG of the plane so that it will rotate to get off the water.

RE: Take-off problems
 

Thanks for the advice. I will change over to the .60 and see what happens. Another thing I thought about is that since the water wasn't very smooth for a plane this size, it really didn't have a chance to rotate over onto the step and gain speed because with each new wave the tips and ends of the floats would be in the water again.

LT-40

RE: Take-off problems
 

Your LT-40 weighs 9.5 lbs on floats? That's incredibly heavy - what are the floats made of?

The LT-40's big wing will be a problem in any crosswind situation, and you will have to be very careful turning across the wind. Holding up aileron on the upwind wing (i.e. as if banking into the wind) will help but when taxiing you don't have much airflow over the wing so the aileron authority will be limited. Ask me how I know :eek:...

I have my LT on slightly oversized floats with fairly tall struts so that it stands quite high in the water. This avoids sucking water into the prop except in very rough windy conditions.

RE: Take-off problems
 

I put our club LT 40 on Goldberg 36" ARF floats, and with a tower pro .46, I can get it off the water in about 50' and hold onto a darn good climb. Most flying is done around 1/2 throttle. I would say you have a much bigger issue than the .46, and putting a .60 on it, will just mask the problem. As mentioned above, you are pretty heavy... like 2 pounds heavier than 3 other LT 40's at our club that are on floats...One of them is electric and it will out perform the glow versions!