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SIG Kadet LT-40 w/O.S. 65AX

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Old 04-29-2013, 01:47 PM
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kadetman
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Default SIG Kadet LT-40 w/O.S. 65AX

I have 2 SIG LT-40s one w/OS 46AX and one electric, 1 Senior w/OS 46AX, 1 Seniorita electric, and 1 LT-25 w/OS 35AX. All are tail draggers except the Senior. Building my 3rd LT-40 from a kit w/pontoons. Want to put an OS 65AX on it. Has anyone ever done this?
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Old 04-29-2013, 04:56 PM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

I once modified a LT-40 to take a variety of engines, to use as a testbed and to break those engines in.

I've had engines as large as .91's on the LT-40 but I had to throttle back so as not to rip the wings off, and I also had to watch the prop clearance. I think that the largest one that I could run was a 14" and that was with the Dubro heavy duty landing gear, not the wire gear that is included with the kit.

The 65 will be a good choice, I think, for float flying but if you run her full bore, she is going to climb like a homesick angel and the wings might not take it. Just a word of caution....

Just my $.02

Bob
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Old 04-29-2013, 05:24 PM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

A friend put a Magnum 75 2 stroke on one. He flattened the wing and made a tail dragger out of it. It flew nice and was fast. He made the mistake of lettings someone else fly it..............
You might like one similar, a fun plane!
I have a LT 25 with a Thunder Tiger 36 that I plan on putting floats on....the 36 is plenty of power forsure.
Keep us posted
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Old 04-29-2013, 05:26 PM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

I forgot, the Lt 40 had one wing bay removed on each side and some beefing on the wing as well as wing bolts...........been quite a while back.
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Old 04-29-2013, 08:47 PM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

Hi Kadetman,

I guess you are thinking of the bigger engine to have enough power for the floats? In my experience a well set up float model doesn't need all that much more power. Emphasis on well set up, you want the right size floats mounted at the correct angle and position. I would have thought the .46 would have been the ideal size.

The other consideration is weight. By the time you add floats and their mounts and sort out a rudder linkage you may find the weight starting to creep up a bit. Now if you add a larger engine, and possibly a larger tank to go with it, plus the weight of the extra fuel you might be getting a bit on the heavy side. Overweight float planes aren't much fun on the water.

Then again if you want the power so you can tear up the sky then go for it, mind you there would be better models than the LT 40 for that.

Dave H
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Old 04-30-2013, 03:04 AM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

I've got an LT40 with an OS 46AX, tail dragger. I bolt on the floats a couple of times a year and it's a joy to fly. Not a speed demon by any means but very solid in the air. The floats are custom foam cores sheeted in balsa and glassed.
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Old 05-02-2013, 06:38 AM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

Thanks guys for the quick responses and good info. Since I fly Kadets you know I am not after speed. Will go with the 65. All of my planes are kit built except for the Senior & Seniorita. Kit is the only way to go. Having built them makes it easier to repair when the need arises. Have thought about using on of the wings off the other two LT-40s but put that idea aside and will build a new reinforced bolt on wing. Should I install flaps on the float plane? Will be back later with questions on the floats.
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Old 05-05-2013, 08:28 PM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

kadetman
I built a Sig Kadet LT 40 in stock form and put a Magnum 65 two stroke on it. It flew great and I liked the combination. The only change I would consider is converting it to a tail dragger. Regards, NM
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Old 05-08-2013, 02:25 PM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

The OS .65LA is an excellent engine. Several years ago, Model Airplane News has a .60 sized engine shootout. The LA .65 out turned the OS .61FX on every prop except the 11-7. A 12-6 or 12-7 is a good choice. The differences were only a couple of hundred rpm, even so, it is a good running engine. I bought 2 specifically for flying off water with .46 sized planes. They have plain bearings, so no ball bearings to rust.

As for climbing under full power, this is a characteristic of planes with a flat bottom airfoil. I recommend 2 popsicle sticks under the trailing edge of the wing to lower the incidence. Here's a good way to check that. Raise the TE with the popsicle sticks, fly and trim for level at full power. Land, but do not reset the trim. Look at the elevator. If it is level with the stab, you're good. If it's down some, add another popsicle stick. If the elevator is trimmed slightly upwards, remove a popsicle stick. What you are doing here is resetting the wing incidence for a higher cruise speed. Once you get the incidence correct, fill in the gap under the wing with silicone, balsa or whatever is handy.

PS: Don't make your floats too small or set them too narrow.
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Old 05-08-2013, 04:33 PM
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Default RE: SIG Kadet LT-40 w/O.S. 65AX

It's good to see that you're out there still giving sage advice, Ed. I still re-read old issues of RCR and there's always something in your columns that I latch on to.

Bob
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