I just ordered a Sig SE kit from Tower hobbies. I believe that's the biggest difference in price of a kit vs the same arf that I have seen. I've got pretty much all the tools except for a jig. Will I need a jig for this plane?

My son and I are just about done with the wing. No you do not need a jig. The wing halves build easy over plans. When you flip the wing over and place the TE on a 1in block that will give you wash in and I don't think you can reproduce that on a jig easily. Do a search as some are enlarging the rudder area, 10oz tank, pull-pull for rudder and some gen building tips.

Pete

No, you don't need a jig, but I didn't follow the instructions as far as blocking up the TE with a 1" strip as it would have produced wash-in as Pete stated. Instead, when it was time to flip the wing, I carefully removed the tabs from the ribs and tack glued them to the top of the wing on the same rib they were removed from. Once all of the sheeting was glued on, I removed the tabs and sanded the tiny spot of glue off. This produced a dead straight wing.

John

I use a metal straight edge to get the spar perfectly straight, same with LE & TE. This bird is a easy build, have fun. There are many mods available durning building, just do a search.

I don't think you want to build wash-in into the wing
This will take from the stability of the craft by encouraging a tip-stall before a nose-stall
I doubt it's very serious here in the SSE build, otherwise the instructions wouldn't be so casual about it, but I can't see how it's advantageous
I'm guessing that it's neglected in the instructions so as to speed up the build
What you're shooting for here is absolute symmetry in the wings - added wash-in will result in a plane that is somewhat more stable inverted and somewhat less stable right-side-up
What you can do is mimic the profile of the tabs by using a tapered strip of balsa...or the above suggested method of carefully re-attaching the tabs
The other thing to watch out for is that your root ribs are nice and square and true...watch out for mild warps in the root rib ply - this can be countered with judicious use of water ie. dampen the side that you want to make more "convex"

I.F.

I build, therefore I am

After doing a fair amount of reading on the SE and going over the kit and plans I don't believe SIG recommended this by error. The amount of washin is small and from the threads I've read I believe most of the SE's out there are built per plans with happy customers. Will post how she fly's per plans.

Pete

Can someone explain what wash-in is? This is my first kit and I'm ready to start. I'm sure I'll have plenty of questions as I work through it.

Wash-in is the opposite of wash-out, Ha!

Sorry.... wash-out is often used in a wing to improve the stall characteristics...it involves making the wing tips have a lower angle of attack relative to the wing root
This is accomplished by "twisting" the wing so that the tip leading edge is lower than the root L.E. and the tip trailing edge is higher than the root T.E.
This means that in high angle-of-attack situations (ie. low speed flight) the stall will occur in-board first and the wing tips will stall later
The result is that the craft will drop its nose rather than drop a wing in a stall, so that it's easier to recover and more predictable (with a tip stall, you never know which tip is going to go down)

This brings us to wash-in...pretty much the same as the above except the opposite...so it should encourage rather than discourage a tip stall in high A.O.A. situations

But like I said, since the S.E. manual is so casual about it, I'm guessing that in this design the amount of wash-in is insignificant for this design and the S.E. should well be able to tolerate it without adverse effects
In principle it's not cool, but in practice you'll get away with it here.

I.F.

I build, therefore I am

Zetor,
You do not need a wing jig to build this plane. I have built two SE's and my recommendation for the wing is to get a piece of 3/4" ply and rip a 1" piece the length of one wing panel, a table saw is needed for this. Build it as per the plans and after you sheet the top and flip it over use the 1" strip to block up the T.E. so it stays straight during sheeting which then locks in the shape permanently.

The plans are NOT casual about this step and make a point of telling you to maintain that straight TE while sheeting.

I also suggest to reinforce the wing sheeting near the fuselage as it is thin and may crack when removing the wing. Add some extra balsa to stiffen that area or at the very least soak some thin CA on the inside to make it harder.

Read the instructions carefully and you should have no problem building the SE and you will learn enough to build many other planes after this one. Good choice.

To close the proverbial loop on wash-in and jigs... I agree: you don' need no steenking wing jig.

I do use a jig for nearly all of my wings and I build wash-in into them all the time (actually a negative amount of it, aka wash-out). It really changes things very little and the jig assures that I get it in evenly.

To wash a jigged wing one way or the other, all you have to do is block one end of one support rod higher than the other rod by the appropriate amount -- then just build away.

Now, the appropriate amount is something to think about... since the support rods are closer together than the leading and trailing edges of the wing, you have to reduce the amount you block the high corner up by an amount proportional to the difference between the wing chord (length from leading edge to trailing edge) and the distance between the rods. Then you have to increase the amount by difference between the the wingspan of one wing panel and the distance between the rod supports.

So, let's say your building a 54" span plane with a 9" chord that's supposed to have one inch of washout (that's pretty close to a lot of planes -- and it has a half span of 27" )... and lets say the jig holes are 6" apart and the bed of your jig is 36" long. You'd decrease the washout amount by the proportion of the rod sparation to the chord length (1" x 6"/9" = 2/3" ) and then you'd increase that by the proportion of the jig length to the wing half span (2/3" x 36"/27" = 72/81" )... which is .888, or darned close to 7/8". So you'd just block the support rod at the correct corner by 7/8" and build as though it was all flat. (The correct corner would be the tip end of the leading edge for wash-in and the the tip end of the trailing edge for wash-out.)

Now, notice that it's only an eighth of an inch from the one inch we started with -- an easier approach that really would have worked just fine (but would have been way less intillectually gratifying ) would be to simply block the support rod by the original 1" and correct the twist with covering tension. You have to measure to be sure the wash is even after covering anyway, so doing the build the easy way and correcting afterward doesn't cost you any work at all.

I opened my kit, turned it over, shook the box and the pieces fell into place. Just added glue.

Seriously, it is a very easy kit. I built it in 2 nights. The wing comes with great instructions and explains it all really well. Just don't cut the wing tube wrong like a lot of people do. It is a nice bird. flys like a dream too. I keep moving my CG backward and it gets more and more fun. I may move it just a bit more. Just gotta watch the tip on final. It is getting close to being squirly but isn't there yet.

You will like it. Great plane.

Build as per the plans and you will be fine. That thick wing is very hard to stall, you can slow the plane down nealy to a walking pace it seems.

I did read somewhere else that a Sig engineer confirmed the wash in is intentional. I wonder if they did this to encourage tip stalls and make it easier to do snap rolls and spins?

I doubt very much that the wash-in is intentional...here's why:

1. If it were intentional, then surely the jig-tabs would reflect this by being that much lower as you move from root to tip -ie. such as to produce the wash-in from the very beginning.
But in fact, the jig-tabs are such as to produce a dead straight wing, which you then must "force" (albeit minimally) to produce the wash-in when you flip it over - this makes no sense and results in building additional stresses into the wing where none would've been necessary - engineers generally don't choose to build stresses into a structure if they can be easily avoided

2. This is an out and out aerobatic design - hence the wing symmetry... any alterations to this symmetry in the service of improved performance will have precisely the equal but opposite effect when flying inverted, so you would be robbing Peter to pay Paul - again, this makes no sense in an aerobatic design which should be able to perform equally well inverted as right-side-up

3. The SSE airframe, by its nature, can hardly be described as needing "encouragement" to spin or snap! - responsiveness and maneuverability were design principles

That said, I would agree with the above quotes in that this is nothing to worry about ...the resultant wash-in from building as per instructions raises the tip TE by 1/8"max., and will have no discernable effect on the performance envelope...so, do what you like!!!

BTW have fun building this one, its a lovely plane!

I.F.

I build, therefore I am