I'm still having a problem with a curved fuselage.
After I glued the fuse doublers to the fuse with titebond I noticed the curve in the fuse sides ( see 1st photo ).
I wet the fuse sides and bent them in the opposite direction for a couple of days and they straightened out.
I aligned the fuse over the plans while building and thought I had it straight.
I'm at the point of fitting the wing to the fuse and took alot of measurements conferming that the fuse is crooked...
I clamped straight edges to the firewall and to the sides of the fuse and took measurements to see how far off.
It looks like the bend is in the wing area.
I'm thinking of making a cut in the fuse side where indicated in the photo.
I think this would allow the nose to go to the left, straightening the fuse and getting the firewall be parellel with the LE of the wing.
I would just double up the ply fuse side when aligned..

Any other ideas?

thanks

Steve

Steve,
First off, you can't check how straight the fuselage is until you bring the fuselage sides into the top and bottom fuselage pieces. Try bringing all of the parts together and dry assembling the sides to the top and bottom of the fuselage. Use rubber bands to hold it all together down the entire length of the fuselage. This type of fuselage that uses interlocking parts actually count on all of the parts being together to be straight. It's the way it is designed. Taking the measurements like you are you won't be able to tell if it's straight or not. And if you go cutting the sides of the fuse now you will more than likely make things worse.

Ken

I'm supposed to place the fuse over the wing to get the position to drill the holes in the TE of the wing.
Then I glue the floor of the cockpit in place. like you say, this may straighten things out as this looks like the area in question...

This is what I was doing when I started noticing the alignment. I was reluctant to drill the hole locations in the TE the way things are lining up????

I'll see what happens with the cockpit flooring in place with rubber bands. If I do glue this in place first I'd have to figure out how to get the hole location for the trailing edges of the wings. Or drill the holes then put the flooring in and see if it straightens out???

Ken, If the fuse was complete would these angles concern you???
Seems pretty far off if this is what I end up with?

Thanks

Steve

Before you drill try framing up the entire fuselage dry first. Then see how it looks, and check for how straight it is. I have forgotten, what kit is this??? Is this a Tiger kit??

Ken

Steve, another point, the firewall is not a good sorce for determining square. A lot of kits build in the right thrust into the firewall and it is not uncommon to have the firewall 2 or 3 degrees off square. The same goes for down thrust. Square the sides to the former at the LE of the wing and judge the fuselage from this reference, not the firewall.

Don

I would band the whole fuse together then take your measurements. I would be willing to bet once you have all parts together the fuse will be fine.

In the pictures, the two straight pieces you have clamped to the fuse, are those the fuse sides or just pieces of wood or something you clamped to see how far off you are?

From reading your post it sounds like you have already built the fuse, glued the top, bottom and sides together. I think most people that have answered so far are assuming those two pieces you clamped on are the fuse sides, so they say you are ok and it will turn out fine once glued. If I'm right and the fuse is done, I do think you have a problem and need to straighten the fuse out.

You're not aligning the wing with the fuselage. To do this, you should use a piece of cotton string or a stiff wire. Put a pin into the fuselage at the centerline of the tail. then use that to set the distance to the rear corner of the wing. Adjust the wing as necessary until the distance is the same on both sides. If necessary sand the wing saddle to allow the wing to sit properly when adjsted. If there is some small misalignment between the fuselage sides, you'll not likely notice it when flying the plane.

Do not cut the fuselage.

Brad

This is how you determine that the wing is square in the fuselage. Do as Bkdavy said, measure the distance from the centerpoint of the tail to the wing tips and adjust until they measurement is the same.

Ken

This is a tiger 60 kit.

The fuse is all glued except for the flooring of the cockpit. (plans call for this flooring to install after the following step is done)
I mounted the fuse on the wing to get the position of the TE holes. ( do this by passing a small drill through the already mounted blind nuts through the TE of wing)
As indicated by others, I measure from wingtips to the tail of the fuse. I get a difference of about 3/16" - 1/4".
I could live with this amout??? But as I sight down the fuse I get back to my original problem with the fuse sides haveing a bow in them..
To try and measure any misalignment on the fuse I took some corner moulding stock, which is pretty straight, and 1st clamped it to the fuse sides at the back of the fuse.
These straight edges ran flush along the sides of the fuse up till it got to the wing saddle. the straight edges run on in a straight line. If the front of the fuse was aligned with the tail I sould have equal space measured from each side of the nose out to the straight edges. I repeated this setup with the straight edges clamped to the sides of the fuse in the nose area. (this is the picture I posted) These measurements confirmed the previous measurements. The fuse hase a bow in it.
Clamping a straight edge to the firewall also indicated the same bow direction although I realize some of this angle could be designed for right thrust engine offset??? Seems excessive to me though...

I just tried putting the cockpit flooring in and I dont see that its going to pull anything into alignment. it just fits into place. could be wrong though.

I also tried laying the fuse on top of the plans. It doesnt look to bad using this method of checking!

I've never tried making these measurements on a plane before (clampling straight edges to the fuse sides ) so I dont know if this is unusual? I will try it on my ARF trainer for comparison.
If not for my original problem with the curved fuse sides I might not have even looked at these measurements.
If this is a problem it would be best to resolve it now as opposed to continuing on with the build???
OR, I'm driving myself crazy for no reason?

On the bright side, the wings and tail surfaces are looking good!

Thanks for your inputs...

Steve

This pic shows the two straight edges clamped to the nose of the fuse. If everything was straight the measurements out at the end of the tail should be equal. as you can see the differ by .75" (everything is glued except the floor of the cockpit whick is held in with rubber bands)

I just checked the same measurements on my skyraider trainer and it shows a difference of .125" VS. a measurement of .75" on the Tiger Kit.

Again, indicating a bow in my tiger fuse....

Steve

I think you are driving yourself crazy. The fuse looks fine to me.

Mount the wings and move on.

I don't think I'd trust the way you are measuring.

I think a better way to measure if there is a significant bow would be to make four centerline marks on the fuselage. One line at the firewall, one line in front of the wind saddle, one half way between the wing saddle and tail and one line near the tail. Stretch a piece of string between the front and rear marks and see how far off the string is on the two in the middle.

Go to Ken's post with the picture of how to set up a wing and zero the difference between the wing tips. drill your wing mounting holes and move on. As long as your wing, and tail feathers are set up right it will fly fine.

Also remember, the sides are curved from the nose all the way back to the tail. The widest point is somewhere around the wing. It is thinner before the wing also.

This is model aviation, it ain't rocket science.

The first fuselage I built for my Sig Kavalier I built on it's side instead of on it's bottom. That put all of the curve on the opposite side and made it resemble a banana. It flew great all the way up till the wing seperated at 100+ feet. (I forgot to epoxy the wing dowels into the wing). I made the second fuselage right. (And this time I made sure to glue the dowels). I don't remember it flying any different. I still have the Kavalier, and it is a great flying model.

I agree for this plane.
You'll never 'sense' it when you fly it. Be sure to keep your next build straight when the time comes.
When the planes get bigger, you won't want a bowed fuse.