I bought an LT-40 to teach my girlfriend and her son to fly on and I need a few ideas on how to shed some weight. The problem is that it is already 90% built. I but all of the pieces of the model engine and radio gear on a baby scale I have and as it stands right now I am right at 6lbs. The finish is Koverall and Dope so I knew it was going to be on the heavy side but did not take the time to drill some lightening holes in the ribs and various other parts during construction, wish I had now.

I have covered all the parts and brushed two coats of clear on everything but the wing so all that is left to do is clear coat it then spray the colors and seal the whole plane with another coat ot two of clear. Not sure what the total would be by then but figured about 6lbs 4-6oz or so. I would like to get it down to about 6lbs even if possible. I figured I could ditch the rubber Du-bro wheels for some foamies and save a few ounces there, but can't think of much else to save any weight with. Battery pack is a 4.8v 600mha unit. Engine is a K&B .48 2 stroke. Got any Ideas?

I suppose even at 6lbs 8oz it should fly pretty good, but I should have taken weight into more consideration during the construction. SIG claims weight should have been between 5.5-6lbs. Does anyone have a kit version built up out there and if so how much does yours hit the scales at?

Thanks,
Blaze

Blaze, I don't have a scale, but I've been teaching on LT 40s for at least 6 years now, and I've seen them with .30's and .90's up front. I don't think an extra pound or two is going to hurt the performance of a LT. I would use a hot .46 or better though

HTH
Tom

it will fly fine don't worry

ditto, 6lbs is nothing for that plane.

Thanks, I sort of figured it was not too much to worry about but, I knew there were others who had flew this plane at various weights. Might even just leave the stock wheels on it.

Blaze

Even at that weight it'll be a floater. Good Luck and enjoy.

Mike

It will fly OK at that weight, but somehow RC flyers have come to believe that overweight crooked models are OK if they have a big enough engine.......I'm not picking on you, really. It just amazes me. A light, straight airplane is so much easier and fun to fly.

If you want, I can send you a scan of an article about light dope paint jobs that is pretty good. Koverall, by the time it is painted, is one of the heaviest coverings around. It is great on large ships, but a bit of a burden on smaller ones.

A nice dope finish is sure nice.

Kelvin

My .46 FX makes this plane jump! If you have similar opwer, you should be fine!

Since you haven't started painting, the obvious solution would be stripping the fabric and using Ultracote. Sorry to suggest going backwards, but here's two reasons.
First, you want this trainer as light, slow, and easy-to-fly as possible. Teaching a "significant lover" is already tricky enough.
Second, as it takes rough landings and other abuse the film will be much easier to repair.
I like Sullivan's lightweight wheels.

The problem isn't in the covering, its probably the wood selection, likely a luck of the draw thing, like most kits. Koverall and 5 coats of dope is at least as light as any film covering. If you start glopping house paint or epoxy , or automotive paint all over it, that changes things though. Anything less than 7 lbs on your LT 40 will fly just fine, that thing has a huge wing area, never saw one that didnt' fly well no matter what it was covered with, and on any ol plain bearing sport .40 as well.

I commend your choice as that is a great trainer. A K&B .48 is overkill for that plane. I've seen them fly extremely well with a plain bearing .40. The K&B will easily out pull the OS .46FX and likes larger props also. I suggest you use a slightly large prop with a slightly small pitch to stop over speeding the airframe and allow steeper climbs without stalling. Maybe a 12-5?

finish the plane then go fly is my advice,plane will do fine.Any thing else is to start from scratch