I have a quick question:

(Not that I can fix it now) BUT... I am building a Sig LT 40 and I just finished the first wing and the trailing edge where the ribs get installed was not lining up with the plans, so I lined it up with the most outside rib and then lined everything from there. Figuring that if that rib is out of alien then everything else might. (I have learned a lot from this build so far). But when I put the shear webbing in between the ribs, it pushed the ribs ever so slight out of 90 degree (probably 91 at the leading edge) side to side. they are 90 degree everywhere else (up and down).
So the ribs on the outs sides of the wing half I build so far are perfect in all directions but a few on the inside are not a perfect 90 with the leading edge. (I did not want to cut the shear webbing since it was "laser cut" and read somewhere that you should line up the ribs with that). That was my mistake and the second half will come out 100 percent better, and the rest of the planes I build.

My question is will this greatly distort how the plane flies if the ribs on the inside are not perfectly 90 degrees front to back?

thanks for any advise...

Patrick

If you built the leading and trailing edges on and to the plans it won't make a gnat's ***** of a difference. If, however, the chord of that wing (total width) is compressed because the ribs were angled it will make a tiny difference (less lift vs. the opposite side). Once trimmed in flight you'll never detect it because of the dihedral built in . . . unless it was a major difference.

The LT-40 is a very forgiving and self-correcting design. I helped an Explorer post build four of them and you never saw four differently constructed versions of the same kit with no intentional bashing. There must have weighed a full pound different between the four (one group used two bottles of Titebond and another only half of one bottle!). But they all flew very well and it was really hard to pick the heavy one unless you flew it immediately after the lightest. Great choice for a trainer and first build.

thanks Charlie P for your insight.

I agree with Charlie. The LT-40 would probably still fly like a champ if it was put together upside down with toothpaste and band-aids. A fantastic airframe.

Keep building and fly it. Trim the shear webs if you have to. You generally have to fine tune their fit anyhow.

This is a good example of why building a model is a good mental exercise. It will improve your ability to foresee problems, to visualize steps needed to take to have a desired outcome, to exercise judgement when dealing with imperfections, to improve your focus on completing the simple tasks, to better learn how to prevent the simple tasks from becoming more work than they should be. It's all mental gymnastics and even some kits no matter how well they are done require some problem solving. As you gain experience as a kit builder, you'll come up with your own favorite ways of handling some details in the kit that look like trouble. There is a certain level of perfection that you want to strive for, but it's nowhere near that of a watch maker. With the interlocking parts of today's kits that can be assembled in stages dry, it's never been easier to avoid gluing yourself into a corner.

Another thing to remember when building a kit - the more you build, the better you get. And the more you build the better you quality will with each build.

Hogflyer

I am already getting excited for my next build (and I have not finished this one yet), now figuring out different ways to build. I have been reading A LOT about building but not until you do it is when you really learn how to do stuff.

I am thinking about a Sig 4 Star for my second plane. Tail dragger, bottom wing. I figure I would build it after this one to keep practicing this skill and to get over the slow winter, come summer I should be able to flight it after putting a lot of hours on the trainer.

Thanks for the advise.

Quite frankly, almost all the Sig designs are great kits and most fly well too. The LT-40 is flat out the best trainer on the market, and the 4-Star a good second airplane. I would also recommend their Something Extra for the third airplane.

Hi im just a begginer and just built a lt 40, I also found the trailing edge and ribs did not quite match the plan. As long as you build the wing flat and have the root ribs built in line with the plan you will be ok. I did findminor by eye adjustments to shear webs are needed.

These small tweeks (attention to detail) as you go will result in a good build.

Its great to see the final product and flys so well.

Got a somethin extra on the build table the now. But before I fly her I am going to build a four star and master that first.

Any more questions about the build just give us a shout.</p>

raydar: did you mount the wing on perm?

The second wing came out perfect, and looking back you really cant tell from looking at the wing that it is off at all.

Thanks for your help!

Patrick

No I just have not put the dowels for the wings on yet in the picture. Thought aboutmaking perm wingsbut glad I did not as the rubber bands that hold a trainer wing on are there to give a bit of "give" in the event of hard landings and tumbles.

My plane was put into the safety fence on a dead stick second time out and I think the damage would have been far worse with a fixed wing. Think the fusalage or wing root area would have suffered.

Done a 24 hour repair and flew the next day.

Rebuild pics in "crash and build" section of forum.

First two pics lt40 damage, third pic is the somethin extra wings.