Wide body modification?

[High Country 69]

So I'm planning to have my 2nd wing complete through the brush coats of eko fill by this weekend and  ready for spray coats so I'm preparing to get back to work on the fuselage. I've decided to remove the stringers and redo it with the wide body modification. My question is what type of tubing should I use for the stringers? I'm thinking 1/2" aluminum, but how thick and does it matter what type of aluminum I use? what would be best? Not sure what the KF's have. next I was thinking about just putting a small piece of tubing to hold the stringer off the front of the airframe aprox 2" then just blend it back in to the airframe with tubing rather than bending sheet metal like most of the modifications are done. I'm not sure that I can bend matching pieces of sheet metal with my equipment and I would hate to have one side be different from the other. what are you guys' thoughts on this? anyone know how much it costs to just have the pieces made, I think Murel Williams does it. may need to give him a call. has anyone here done this modification before... pics just want to have all my ducks in a row so it will be done right. also I was thinking about using Hysol for this modification rather than welding partly due to using aluminum on steel of course.

 

-Robert-

[EDMO 1078]

Cant you get some welding done to make the rear of the doorframe stick out wider?

Structurally, that would be a lot stronger. Then just cover it with fabric.

Check out my Foxy Flapper Fotos in the Kitfox IV section, I think - you can see I used the same size tubing as the original, but it makes it 3 inches wider on each side, and a lot stronger.

You have to re-bend the rear of the doors to fit.

You can use aluminum, steel, or wood for the stringers - just brace them with standoffs and hysol.

ED in MO

Edited 5 Jun 2013 by Ed In Missouri

[High Country 69]

Maybe I was a little unclear, I do intend to use steel to widen the door frame area then bend the door frame to match. I was just going to use the aluminum for the stringer. my concern was how thick of tubing should I use for both the aluminum and the steel .025? .035? 6061 for the aluminum? and I was thinking about using tubing rather than bending sheeting because it would be easier for me to make both sides match. hate to bend one side different than the other if I go that route.

 

-Robert-

[EDMO 1078]

Robert,

You have me a little confused about the sheet metal (for stringers?) I haven't seen that on any - but not familiar with all Avids.

The early kitfoxes used a wood stringer, guessing about 3/8 thick by 1/2 inch wide, rounded on outer edge. Think the later ones just used a 3/8 aluminum tube - but 1/2 inch would be better, IMO. I used steel over my baggage and battery doors, and haven't decided what to use for the rest, but probably will go with aluminum. .o35 would be good for steel - I would go heavier for aluminum. I'm not an engineer tho - just have to go with what somebody used or a guestimate.

I wish I had welded in a starter piece for the stringer at the widest point of my extension, but didn't think of it until after blasting and painting - so now it will be a support piece and rivets and Hysol there.

EDMO

[High Country 69]

Apparently i'm not to good at communicating so I will try with a pic (yes i did use MS paint so its not much better than my writing sorry)

1st pic is the traditional way of widening using bent sheet metal

2nd pic is my drawing of how I want to do it using tubing instead

 

what are your thoughts on doing it this way and for the materials I should use?

[EDMO 1078]

Your drawing looks like the same thing that I did on my Kitfox. I used the same diameter .035 wall steel tube that the fuselage door opening was made of. This adds a lot of strength as well as elbow room.

The only thing missing on yours, and on mine, is a short piece of smaller tubing pointing back from the widest point, so you could slip your stringer over it to support that end of the stringer.

The only thing you have to watch is farther back on the sides, to make sure you haven't interfered with the strut swinging back enough to fold the wings completely - That should not be a problem if you blend back to the first bay to the original place for the stringer.

Weld On!

EDMO

[High Country 69]

my plan was to leave the rear part of the stringer right where the original ones were supposed to be so hopefully i wont have any clearance issues with the wings folding back I don't reckin' I will. I like the idea of using a smaller tube for a stub to slip the aluminum over thanks for that idea. how about my choice of material and size/ thickness? does this all seem adequate

 

-Robert-

[EDMO 1078]

Yes, it all looked OK to me. I replaced my wood stringers completely because I had to take it off for welding. Blending the new back to the old should work just fine.

EDMO

[akflyerbob 41]

I did a wide body mod on my mod 4

I bought a kit from Williams but it wouldn't fit, the pieces were not long enough

so I did used them for a pattern

As you see, I also widened the window area to blend the fabric

also used the wood stringers

Edited 9 Jun 2013 by akflyerbob

[High Country 69]

Thanks Bob, I was wondering about the window area, I would like to keep it. I can't seem to find any local suppliers for the materials and it will put me back probably another two weeks plus to do this so now I'm starting to try and talk my self out of it. I really just want to be flying again. I will be doing most of my flying solo so it will not be needed and if I'm not it will be my wife and she's pretty small. we will be doing the bubble doors for sure so that may be all we need. My wing is over built for this airframe partly with the idea of replacing the fuselage with a mk IV at some later date and keeping our wings. hmmmm decisions decisions I will make a couple more calls for 4130 locally today, what type of wood is used for the stringers if I can't find any local aluminum sources?

 

-Robert-