conduit for airstarts

I am using a 3/8th " fuel line as a conduit for my Magnum project, it has a flare on one end and filed smooth on the other end.
It has some weight and I need to have a pair of conduits for 2 ignitors in each.

Are there any other conduits like copper, PVC, etc. that you recommend and that has less weight? Who sells them?

Will steel conduits cause arcing ?

One of the conduits are epoxied, I can take the epoxy off with the Dremel and put other types of conduits you recommend.
Thanks, Mark

Would air line like used on machinery work? There are many types of fittings you can use with this type of line also, such as bulk head fittings. Just a thought you might try and very light weight too.

I picked up some aluminum tubing at the local Westlake Ace hardware store that I use for my airstart conduit, very lightweight.

bmhiii

I used ( I think) 5/16" AL tubing from the hobby store ( K&S metals) on my last air-start rocket. they come in 12" & 36" lengthes.
They come in Brass or AL.

https://www.ksmetals.com/



JD

You could also run small-gauge permanent wire, epoxied through the rings, then use connections of your choice at either end to connect up with. I.E., For electronic-bay bulkhead setups, I use male/female +/- jacks for airstart connections. When the flight's over, the e-bay unplugs. Clean looking if you ask me, but then again, I may tend to over-build at times : )

Mark,
On my 7 motor cluster (3 airstarts), I used threaded lamp tubing that went from the avionics bay, to slightly out the aft of the rocket, about 32" long. This can be purchased at just about any harware store or Home Center in lengths up to 36".

The fact that it's fully threaded, really makes construction a breeze, seeing as how you can just tighten the nuts around the centering rings as you epoxy them (and your motor tubes) in. I clamped all my centering rings together with small pieces of mmt in each hole, "then" I drilled the 1/2" dia. holes for the conduit through all of them at once. That way, when you get all your motor tubes epoxied in, you know that all the holes for your conduit will line up. The lamp tubing as a conduit also added a bit more strength to the entire fincan assembly!
I even happened to find some small plastic caps that threaded on the ends of the lamp tubes I drilled a 3/32" hole in them and they held the ignitors quite well.
Central Motor=K550
Outboards=(6)-J570's....2 at a a time......
Twas a beautiful flight

I didn't have any problems with arcing at all, but then my conduits weren't close together either. That may make a difference.

Hope I helped
_________________________
Chris Emich
NAR #84102
TNRocketry
_________________________
In the Works............
8" Dia. Upscale Bulldog L3 Cert. Rocket
Known as: Bulldragon

Thanks guys for the advice.
Mark

pr_rocket04 said:

You could also run small-gauge permanent wire, epoxied through the rings, then use connections of your choice at either end to connect up with. I.E., For electronic-bay bulkhead setups, I use male/female +/- jacks for airstart connections. When the flight's over, the e-bay unplugs. Clean looking if you ask me, but then again, I may tend to over-build at times : )

Click to expand...

Could you share an example of the +/- jacks you use? Thanks

802high said:

Could you share an example of the +/- jacks you use? Thanks

Click to expand...

I'll admit to being curious for pictures to this design as well, but I will point out that the post you quoted is 14 years old, and that poster hasn't been online here in quite awhile

Nytrunner said:

I'll admit to being curious for pictures to this design as well, but I will point out that the post you quoted is 14 years old, and that poster hasn't been online here in quite awhile

Click to expand...

Haha saw that after posting. Also found another thread with a lot of disconnect options.

I have used copper foil tape on the outside of the air frame. No reason you could not on the inside.

I have a rocket, I've been working on and off again from about 5-6 years now ( if not more)
I had little room left to have internal conduits, I had to use some external conduits glued to the root edge of the fins. I would love to finish it but, hit a snag; couplers won't fit the 6" tubing.

+1 On the Lamp threaded tubing, I've used it on a few builds, and like Chris TNR said you just tighten the thin nut on both ends. Works perfectly.

There's a far easier way these days..
Technology has come so far, you may as well use it..
Marsa Systems makes a Pyro unit that's really small and you mount in the motor mount
( outside of the motor tube of course )..
It does the airstarts..
It communicates with the altimeter in the av bay via bluetooth..
No conduit necessary..

Teddy

You can get carbon fiber tubing on eBay if you are looking for low mass. Not too expensive for the thinner stuff. Used a lot on drones these days.

With the demise of disposable drinking straws I have seen bamboo and also stainless steel ones available that might be suitable.

Tap Plastics has black fiberglass tubes with an ID as small as .219. Pretty inexpensive too.

I have a 29mm susstainer with a 24mmt. I just glued 2 pieces of flat plastic on the mmt and then dremelled out a shallow groove between them to form a groove. Just run the wires through that.

fiberglass and carbon tubing from your local (or internet) kite store!