Joining methods for carbon rod truss structure

[OmegaDot]

I'm toying with the idea of building a scale micro-heli that would have exposed (visible) trusses in the fuselage structure. The material would probably be 1mm corbon rod or similar. The question is what should be done about the joints? Thick CA on butted ends, wrapped in thread, pin in holes, some other reinforcement?

[ELGEE525]

Hi-
I 've had good results in finding a carbon rod a bit bigger than the ones I'm using and drilling it out to make a sleeve joiner.Or, a carbon tube works if you can find the right size.Butt joints using carbon tape as a wrapping works but isn't as stong-depends on what appearance you want. A Bell 47 tail is difficult as welded angles are hard to dupilcate in scale, and some joints are multi rod joints.If weight isn't a problem,cut and radius each rod to fit,tack with superglue and reinforce with epoxy.if you are careful with the epoxy, you can almost make the joint look like a welded joint.
Small triangle gusset plates made from carbon sheet are another option on multi tube joints,put them in the inside of the framework so they won't show as much. I look on E-Bay under"carbon scraps" - not always there, but over time, things do show up.
Oh, I just remembered something- where say,three rods meet,like at the end of a tailboom,I've found a tube just big enough to press all three in, and and glued all three inside it and then filed the wholle thing down to look triangular-it becomes one piece.Then I wicked in some super thin superglue to reinforce the whole thing.
Hope some of this helps.
Larry G.

[Hoverup]

Built my Bell 47 truss with 1 and 1.5mm CF rod and used carpet thread to wrap the junctions. Soaked all joints with thin CA, hit it with accelerator and painted the assembly. Very light and strong and a lot easier than joining with tubes. For micro scale the appearance is fine. Mine is based on an early H'Bird chassis.

Cheers - Boyd;)
AMA 80393
Major USAF
Retired

[OmegaDot]

Thanks guys!

[T.J. Kong]

Boyd,
That's a beautiful Bell. Would you mind posting some more pictures, so that we can see the whole thing. Also, thanks for the information, as I'd like to do an R-4 and was wondering about the truss structure as well.

[Hoverup]

Thanks for your kind words. This is one of my favorite subjects. I'm working on a Century .50 IC size Bell 47 e-conversion with a Hacker C50 16XL and 6s4p 8880mah Lipolys for the new year.

Cheers - Boyd;)

[T.J. Kong]

Wow...Thanks!

A bit off topic but....As soon as I get my new TRex up and running (Thanks Santa) I'm planning on starting on a 1/24 scale Huey (with Hummingbird mechanics). A few questions if you don't mind. What is the green board near your sevro? Is that your mixer? What is the lightest acceptable gyro in your opinion? I'm thinking of a PG-03, even though I'm not real happy with the revo mix on my JR6102. Finally, I'm new to brushless motors and am trying to figure out how to size a brushless motor. What motor would you recommend? I see Madguns used a Razor Micro on his Huey and Pitts used a Himark 2015-4100 on his Bell 412.

Thanks

[Hoverup]

.............. A few questions if you don't mind. What is the green board near your sevro? Is that your mixer?

It's a CSM 180 HH gyro and I think that is the lightest HH gyro but I may be mistaken on that.

.............. Finally, I'm new to brushless motors and am trying to figure out how to size a brushless motor. What motor would you recommend? I see Madguns used a Razor Micro on his Huey and Pitts used a Himark 2015-4100 on his Bell 412.

Thanks

The Bell 47 has an Astro 010 with a Phoenix 10 ESC. I really prefer the Razor MicroHeli V2, Hacker B20 22s, but a Himaxx 2015 4100 works well also and is a little more affordable.

Happy Holidays - Boyd;)
AMA 80393
Major USAF
Retired

[ejp998]

Hoverup

I have a dragonfly 22D Micro. That I'm thinking of changing to a Bell 47 (MASH) scale helicopter, scratch built.

I chose the bell for a number of of reasons;

1. I really like the simple classic look with the bubble canopy/exposed mechanics
2. Simple design means light
3. Twin rotor baldes is correct
4. Easy fabrication (Bubble Dome/Fuel Tanks/Stretchers/Skids/Tail latice inc rear rotor skid)
5. Wide landing gear (beginner) can be hidden under Stretcher's

What did you use for a canopy. So far I've started on a canopy using two coke bottle (2ltr plastic round) tops glued together, but that leaves a seam.

I'd rather scratch build this so buying a model is probably not an option at the moment.

[Hoverup]

PM me your e-mail address and I'll send you the .jpg files with the construction article and plans. I also have a spare canopy and fuel tank set if you are interested.

Cheers - Boyd;)

[ejp998]

Thanks hoverup, you have mail!