Mid-Power Rocket Concerns

[Soham Karalkar]

Hello! I'm a high school freshman getting started in rocketry, so far I have 3 launches (one successful) under my belt thanks to ARC.

I already began assembling my mid-power BT-80 rocket for a personal launch but have some concerns.

I know one should NOT use a PLA printed motor mount, however I want to try it anyways as a little experiment. The thing is, I don't want this experiment to become an explosion on the launch pad, so I thought of ways to protect the mount from an F-42 motor's heat. So far I've got a cardboard liner covered in 15 minute epoxy in between the motor and the mount.  Would this setup work, or is this just a plain bad idea?

Also I haven't been able to find any launches for mid-power anywhere, I'm new to this so is there a certain site or event for these things?

If anyone has any advice on the matter, I would greatly appreciate it.

[Emma Humphries]

Hi Sunar, 

We hold low- to mid-power launches (ceiling of 300 m/1000 ft) at Brigantino Park in Hollister, CA (South of Gilroy.) Watch the announce list and the website for notifications. The officers are working out a schedule with the city. 

A paper liner in a PLA mount is a common method for protecting the mount. You could also try printing the mount with a higher temperature plastic such as PETG. 

The paper liner adhered into the mount will also increase the mount's resistance to shearing on the layer lines. 

On a mid-power rocket, a motor mount with plywood centering rings and through the wall fins is a proven technique so I would use that as a baseline to compare your project to. 

Looking forward to seeing it fly!

Emma Humphries

LUNAR Board of Directors, At Large

NAR 27698, L2

 

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[Jack Hagerty]

Hi Soham -

First off I applaud your approach, thinking of the materials involved from a design perspective! 

What you suggest would probably work. Paper is a good insulator as can be seen by black powder motors that can be held in the hand after firing, even though the inside combustion was 1,000 F or so.

That said, I agree with Emma that the paper tube/wooden ring setup works really well for mid-power, so there's no reason to go to the expense of printing the motor mount. Unless, of course, that's the thing you're trying to develop.

- Jack

 

Jack Hagerty, ARA Press

http://www.arapress.com

 

"I would do anything to regain my youth…except take exercise, get up early or become respectable." – Oscar Wilde, The Picture of Dorian Gray

 

If anyone has any advice on the matter, I would greatly appreciate it. --

[Soham Karalkar]

Thank you both so much for your insights on this, I think this information is allowing me to create a backup plan.

Since the paper/wooden ring setup seems to be reliable, I think I'll make two rockets: One with the wood + paper tube mount as a control and another with the 3d printed mount + cardboard liner, and see how they hold up against each other, as Mrs. Humphries suggested.

I have my rocket mainly assembled, just need some electronics done and it should be ready for launch! (Once I find an event to launch at, brignatino has no launches yet?)

[do...@eljay.org]

If they get a new launch scheduled it will show up on http://www.lunar.org/ both under “next launch” and there’s a google calendar.

To view this discussion visit https://groups.google.com/d/msgid/lunar-general/d6718070-f770-49c5-9eb7-7ff7570e44cbn%40googlegroups.com.

[Jack Hagerty]

Good plan!

The Brigantino launches are a work in progress. Just keep an eye out here (or any of our other media channels).

 - Jack

 

 Jack Hagerty, Section Advisor

 LUNAR #0002

 http://www.lunar.org

Hotline: (925) 443-8705

 

 "Our main goal for a long time [developing the V2] was to make it more  dangerous

to be in the target area than to be part of the test crew."  -- Wernher von Braun

 

[Soham Karalkar]

Got it, until the next launch date, I'll just get my rockets ready for flight!

Again thank you all so much for your help!