john josey

A triangular structure is the strongest there is, so i would defo add the cross brace Robert. It may not be needed, but there is no benifit to not fiting it.

The cabane's on my own are a completely different set-up. TC has used 3mm piano wire with the aerofoil section being fabricated from oval shaped balsa halfs with the recess cut out the middle to fit over the piano wire. The piano wire is fixed to the fusalage with what can only be described as threaded eyelets. If you were to take a piece of threaded rod about 1" long and hammer one end flat then drill a hole that the piano wire can pass through then drill a hole in the fusalage side and pass the threaded part through, and a washer and nut to pull the wire tight against the fusalage side to the piont that you cand move it by hand but tight enough that the wire wont fall under it's own weight. With that done, you can make very small, accurate adjustments for alignment before you tighten the nuts fully, then smear the whole lot with epoxy.

acerc

Man you guy's have a way of making one paranoid. So, I went looking for a solution for a little more reinforcement with minimum weight gain. Here is what I came up with. In the pic the red circles are where the struts exit the fuse. At that point there is a 3/16 x 1/2" hardwood rail. The hardwood rail will actually have to be contoured for the struts, the black marker in the yellow circles. I will make a smallbracket to fasten the cabane to these hardwood rails. I think this will add the needed support at the center of the cabane's.

john josey

I think thats a good idea Robert, it'll give you peace of mind.

RickBoyer

My Feedback: (37)

Hey Robert,

I used airfoil shaped Chrome Moly, jig aligned and tig welded together, on my Pitts cabane assembly since the drawing called for using welded steel brake line (flattened in a similar fashion to your brass method). I also used flat stainless sheet machined down to a square profile with a hole drilled in the middle, to accept a machine screw and locking nut which secured the assembly in four places to the bulkheads.

Be careful with brass since it is allot softer than CM or stainless.....

Just say'n,

Rick Boyer

Top Gun 2004-2012
Pitts Special S-1S (#1)
Ryan STA
Pitts Special S-1S (#2)

acerc

Hi Rick! How are you doing? What are you bringing to TG this year. I appreciate your concern and you may very well be right. But not having the welding equipment or skill I have to find other avenues. The cabanes will be bolted to the bulkheads and the hardwood runner at the top of fuse. If it turns out not to be strong enough I'll get to do it again. Now if someone (hint, hint)was willing to jig one up and weld it, I would be most appreciative. And willing to pay. I don't, personally, know anyone that is capable of doing such.

acerc

Any volunteers?

acerc

Not much done today, just not in the mood I guess. But I have managed to get the wing cabane mounts made.

WacoNut

Robert,

Hard to tell from your pics but can you run music wire thru your streamlined tubing and silver solder a lug at each end for attaching to the mounts? I would then JB Weld the brass over the music wire.

This would help strength wise, I would be a bit skiddish of the brass. I think you will be fine with pulling and compression forces it is any side load forces you will encounter that worries me with brass. As squirrely as a Pitts can be on the ground and also doing snaps and such you will see alot of side load.

Not trying to worry you just an opinion.
Later!!
Anthony

john josey

I think the flying wires might be functional on your pitts Robert.

acerc

Ok! All this over my cabanes got me thinking. I don't know why but a thought popped in my head and thought I'd try it.
Look at the photo. Now keep in mind I only weigh 170lbs. All my left foot is doing is keeping balance. There will be two, front and rear.

flyingagin

Good expearment. Go for it

Ken

john josey

LOL Exellent Robert !  That clinches it !

acerc

John you refered to yours as a TC. Who is that?

flyingagin

My asking aboutcompressive load at the center back in post 395may have cuased some doubt about the cabanes. I really did not mean to do that and I want to apologize to you personallyacercand any others on this thread that took it that way.

Ken

acerc

No apology neccessary, Ken. It was a perfectly logical question. It's just my anal head could not let go with just my simple belief that it was good. I think that test show's it will be plenty strong.

Think of it like this, if it was weak you would have saved a plane.

flyingagin

Ahhh now I did not think of that. Good thought

Ken

john josey

Robert, TC....Toni Clark in germany the manufacturer of my own pitts kit. I would think the outline on both will be identical, it's just the construction method thats different.

acerc

DUH! I know that one. Thought about getting one. Even emailed him on total price shipped. But my love of the build overcame the idea of a kit. Although the kit would have been much cheaper.

RickBoyer

My Feedback: (37)

Hi Robert,

I still have the machine shop quality aluminum jig that I made for the cabanes and I can fabricate the cabane for you but I would'nt be able to turn it around for you until mid February due to work and travel. If this helps let me know, although it looks like the brass cabane assembly that you have fabricated will do fine.

Let me know if I can help,

Rick Boyer

Top Gun 2004-2012
Pitts Special S-1S (#1)
Ryan STA
Pitts Special S-1S (#2)

acerc

Thank's for the offer Rick. That is very kind of you. I think I'll be ok with the brass.

VincentJ

Just want to chime in here and bring up two points. First, it never ceases to amaze me how willing others in this hobby are to help other modelers in need. In a crazy "what can you do for me" worldit's refreshing to see help and concern from others. Second point, nice legs thereRobert.. LOL

acerc

My brother, you need glasses!!
Thanks for the laugh!

acerc

I was getting set up to start sanding and realised I had not installed shear webs in the top wing. When they are dry sanding will commence.

acerc

I'm still sanding. Will probably be most of tomorrow finishing up the sanding.

acerc

I quit! For the day. Got a club meeting to get to.