fuselage lumber

[Dan Berry]

After the debacle in El Dorado, I need to fabricate a new fuselage for the profile Oriental. There are serious issues at the doublers and getting rid of the existing fuselage will let me look at the wing closely. The wing actually looks structurally sound. A new fuselage will also be shorter at the nose to allow removing some tail weight.
The question: what density balsa should I be looking at? Bear in mind, the plane is a learning tool. I'm guessing 8-9 lb wood.
Advice is appreciated.

[Dave_Trible]

Your guess is pretty good.  Maybe even harder wood on a profile.  Weight isn't usually much issue on profiles but rigidity is both to dampen vibration and minimize the fuselage twisting or springing in windy weather.  I found my profiles best with 7-8# lumber.  When I tried softer wood I had to go back and fully glass the fuselage to rid myself the problems.

Dave

[Howard Rush]

Yep.  Looking at the onboard video of the tail of Mark Scarborough's profile deflecting in the wind, I reckon that one should err on the stiff side.  Besides dense wood, the thicker the fuselage is, the better.   

[Brett Buck]

After the debacle in El Dorado, I need to fabricate a new fuselage for the profile Oriental. There are serious issues at the doublers and getting rid of the existing fuselage will let me look at the wing closely. The wing actually looks structurally sound. A new fuselage will also be shorter at the nose to allow removing some tail weight.
The question: what density balsa should I be looking at? Bear in mind, the plane is a learning tool. I'm guessing 8-9 lb wood.

   
     You don't want to build it to crash standards. I would suggest maybe 6 lb  1/8 for the fuse sides, 1/64 or 1/32 ply for the doublers, and dead light (light as you can get) for the top block. That will be plenty sturdy enough for a small airplane like an Oriental. The flexing is mostly the fuse sides under the stabilizer, so if you want to beef something up, put a 1/32 8 lb doubler inside with the grain running vertically.

    I was using 3/32 for fuse sides when I used 6 lb wood, but I am going back to 1/8 now that I have 3.5-4 lb wood. Building the box structure and closing it up will make a very stiff structure.

    Brett

[Dick Pacini]

Isn't he replacing a profile fuselage?

[Dan Berry]

Thanks for the advice.
It is a kit-built, not ARF. The fuse was nice wood but I sure didn't weigh it when I built it. The plane flew better than me, there was a loose nut behind the handle.
I know that I don't need to do a built-up profile. I also know that 'crash-proof' doesn't exist........
I might be able to use balsa from Joe Wagner's stash.

[Tim Wescott]

Hey Dan

Your guess at wood weight sounds pretty good to me.  Built-up profile fuselages are great if you don't crash them, but kinda hard to repair if you do (assuming you don't crash them thoroughly, which is what it sounds like you did).

[Dan Berry]

Hey Dan

Your guess at wood weight sounds pretty good to me.  Built-up profile fuselages are great if you don't crash them, but kinda hard to repair if you do (assuming you don't crash them thoroughly, which is what it sounds like you did).

Well...thoroughly might be harsh but I did a number on it. Twice. Overnight repair for the first one got it flying but it seems easier to replace it than cobble it back together.
Stunt is new to me. Square maneuvers and me would seem to be .... a challenge. I do wish my brother was around to laugh at my attempts.

[Tim Wescott]

If you're just learning, start building something simple and quick as soon as you get this one repaired.  When you're starting out you just plain crash a lot, so if you want to keep flying, you just plain need to build a lot.