Extreme Air Mail! Mailing Tube Rocket Project!

rwm said:
Nice progress. Maybe fly it without paint first to see the performance? Paint will add some mass.
Robert
Click to expand...


Latex paint is pretty light. Seal it with a clear coat spray paint.
 
rwm said:
Nice progress. Maybe fly it without paint first to see the performance? Paint will add some mass.
Robert
Click to expand...

I was planning on painting the fins and nose cone white and nothing on the tube. Kind of going for the mailing tube look!

For recovery, looks like I am making a 24" parachute after all! The NAR recommends a chute size of 30" for a rocket of my weight but they also recommend a landing speed of 20 ft/s for high power certifications. I can achieve about 18.8 ft/s with a 24" chute according to the software. Shroud lines will be the recommended 1.5x the diameter. Probably it will be an octagon with 8 lines.

For shock cord most information I found errs on the side of too long. Some say 3x the body length is good so I'll figure on 5 or 6 feet. I'll have to hit up the local fabric store and see what I can find.

The chute will be made from a Coglan's emergency blanket. Some recommend thinner 1/4 mil mylar but I'm trying to do as much as I can with stuff I have on hand. Anyone else ever make a chute from an emergency blanket?
 
  • Like
Reactions: rwm
The simulations say in a 7mph wind, the rocket should only land about 25 feet from the launch rod. This is with a parachute with the above specs.
 
Even mailing tube look would be better with a light sheen. Any thoughts a glossy clear coat?
 
It would be a good idea to seal it. I have a can of matte clear enamel.
 
Today I made it to the fabric store and got some elastic cord.

For recovery I'm just using an Estes style shock cord mount. It's got plenty of surface area for a strong bond. It's made form the same heavy brown packing paper that I made the motor tube from. Cord is flat 1/2" elastic webbing. They had all kinds of fun colors but only in 1 yard lengths... I had to settle for black.

EM520389.JPG


I also made up some launch lugs. There's two different sizes. One is a hair over 1/4" (like 0.265" ID) and the other is about 5/16" I'm not sure which will be better. For launch rod I'm gonna try to get a 1/4" drill rod. Any opinion on lug size? Should I go for the looser fit?

EM520393.JPG


Got the motor mount glued in this morning and just now glued in the fins! The eagle eyed among us may notice the small white box from Dorian Tool. If you need ER collets I recommend Kodiak Cutting Tools. They carry Dorian collets and they are beautiful! Polished finish with all edges deburred and shipped in individual little plastic cases. Dorian collets are awesome but not many seem to carry them.

EM520396.JPG


It's tough to eye 'em up perfect... Looks pretty close.

EM520395.JPG


I want to add fillets tomorrow. I think just wood glue will be fine. It doesn't add much bulk like a putty would but it should add at least a little reinforcement.
 
Last edited:
Build a jig for permanent fin gluing! I would say 2 crosscuts as wide as the fins on a piece of mdf and modify to accept rocket.
 
Here's a recent silver soldering jig. Very simple.
 

Attachments

  • Jig.jpg
    Jig.jpg
    2.1 MB · Views: 5
Ya know I’ve been wanting to come up with something for fin gluing.

I’d like to make something that can be more or less universal. Like something that can be used for a 1/2” body tube or 3”. But I’ve never dedicated any serious thought to it.

Estes makes a jig that looks pretty good, I thought about replicating that. Your design also looks pretty good.
 
Lookin' good.
Why drill rod? It's probably more expensive and you won't be hardening this? BTW 1/4" stainless rod is pretty cheap around here if you are worried about rust. I feel like oversize on the lug is better to a point. Just make sure they are spaced far enough apart.
Robert
 
You must log in or register to reply here.
Back
Top