Wing twist

[Flyboy66]

I finished leveling the fuselage yesterday (I think). Left to right is easy. Front to rear I think I am good. The manual says to run a 4’ level under the lift strut carry through tube at the rear and under bottom tube of the front bulkhead. I assume the front bulkhead is the tube under the very front of the fuselage just forward of the rudder pedals. The problem with that is the distance is 50”, so the 4 foot level doesn’t reach. I gave It the calibrated eyeball test and all the tubes appeared to be in line with each other. So then I ran the level over the soar carry through tubes and they matched (level).

So, when I run the level under the front and rear spars to get a reference at the 3” (from the root) for the wing twist, it is almost exactly level. Is this OK, or does it indicate a problem with my front to rear leveling process?

In case I am not writing clearly, I am on Wing Assy page 25 with the full page diagram of “Wing Twist Adjustment”. My number for the ROOT (3” LOCATION) is zero.

Just rechecked my level. Side to side good. At the 3” location, I have to drop the level 1/8” below the front spar for level.

Thanks,

Steve

[PapuaPilot]

You want to put your level on the bottoms of the fore and aft spar carry through tubes. You are right, a 4 foot level is too long, but here are a couple things you can do.
-Take out the turtle deck plexiglass and let the level go out the back.
-Put some spacers between the level and spar carry through tubes so the level is lower (I used a couple of pieces of 2x4).

Looking at the manual it appears there should be a gap under the aft spar, not the front one. BUT . . . the main thing you want to check it that the rear spar is 1/2" higher at the 159" station then the 3" station.

[Flyboy66]

Phil,
the manual says to place the level under the lift strut carry through tube and run it below the forward bulkhead tube. That is 50" and my level is 48" long. It does not say to run it under the spar carry through tubes, which are almost exactly the same orientation as the underside of the aircraft (I checked up top too because I was puzzled about the forward spar being slightly lower than the rear reference a level plane).


So, I am back to what is acceptable. When I place the level under the fore and aft spars, there is a .115" gap under the forward spar when level. The only thing it will affect is the attitude of the fuselage in flight by 1 to 2 degrees. I was wondering in anyone else had experienced this. I will post pictures when I get done with some online training for work.


Thanks,


Steve

[rv9ralph]

Kitfox model 1-3 used the bottom of the fueselage for fore aft level, easy access when building and not covered. Later models use the spar carry throughs, easier to access at all stages of build.

Ralph

[Flyboy66]

Kitfox model 1-3 used the bottom of the fueselage for fore aft level, easy access when building and not covered. Later models use the spar carry throughs, easier to access at all stages of build.

Ralph


Ralph,


thanks for the reply. Where did you get this information? I am held up on the project by lack of info on this topic. I have a KF-7 that I took delivery of on June 5th, and the manual only references taking the level from beneath the lift strut carry through tube and the forward bulkhead tube. Since it is Oshkosh week, nobody is at KF and I am not going to drill any holes until I get confirmation that it is not a mistake.


Thanks,


Steve

[rv9ralph]

Ok, you will find the leveling process on page 82 of the final assembly portion of the S7 manual available on the Kitfox Aircraft website, click through Aircraft Kits, S7, Assembly Manual, Final Assembly.
The manual instructs to use the lower fuselage tubes for fore/aft leveling. Several years ago, if I remember correctly, John M said you can use the bottom of the spar carry throughs as Phil suggested.
Look up the reference and follow on your own decision.

Ralph

[Flyboy66]

Got it. Thanks. Not sure why they have a different wording in final assembly than in Wing Assembly, but I assume it is based on date written and current model of aircraft being built/delivered. Time to drill some holes.

Steve

[PapuaPilot]

I remember having a hard time finding the information about leveling the plane too. Glad you are able to move forward.

[Flyboy66]

Phil,


after a lot of thought, I have decided that I am going to move forward. The fact that the forward spar is higher than the rear spar cannot matter. If I have leveled it properly (front to back) then there is nothing I can do to make the rear spar lower than the front because it is all welded together. If I have leveled it incorrectly, I will still have the required 1/2" of washout at the wingtip if I follow KF instructions. I will just subtract the gap below the forward spar from the 1/2" block that is described in the instructions. The lateral leveling was easy, and I got lucky that my mini sawhorse happened to be as unlevel as my floor and it required no shims to get it precisely where I wanted it. I think it was you that stated this obvious fact in an earlier post. It just took a while for me to come to the same conclusion.


Again, thanks everyone. I am about to drill the $5000 holes, as I call them.

[efwd]

Yep Flyboy, most anxiety producing aspect of the build for me. I had palpitations just reading the start of this thread.

[Flyboy66]

Holes are drilled, and life is good for now. Dropped the pins in, and dihedral, sweep and twist are all where they were before drilling. Today was lift strut spar bracket day. Three are done, but I just did a head count on 1/8 x 1/8 SS rivets and discovered that I must have lost a few. I need 42 for the rear bracket, and have 22 in the bag. I had to drill out a couple in the preceeding work because the heads werent flush with the bracket :(


And of course, as with many other things, I will be waiting again. Normally it is for the post office. But this time it is because OSH is going and KF is closed until the 2nd. I need to order more Loctite 9460 and the additional pop rivets. Time for a break I guess.