piston to electronics bay???? - Northern Colorado Rocketry

This topic has 13 replies, 7 voices, and was last updated 17 years ago by edward.

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February 20, 2008 at 5:27 am #40138
mule
Participant
I have a question for the gurus on here.

I have the PML Black Brant Vb and Sumo that both currently use pistons. I want to play around with some electronics to get use to them and was wondering if I can turn the piston into an electronics bay and still use it as a piston?

BTW, I have an RRC2 mini that I want to put on board and just use the altimeter.

I’m planning on being at the March 1 launch and doing the L1 cert (using the BB) with Jeremiah. So I figured after the launch I would try it out or just do the Sumo and leave the Brant alone for now. I was also thinking of making a separate bay for each rocket so I can change them out with the pistons if I want.

I have plans to add another length of tube to the Sumo and do it the right way……
What do you guys think?
Thanks
Greg
February 20, 2008 at 3:18 pm #46941
edward
Moderator
Personally I wouldn’t put my electronics in a piston and still use it as a piston. Just the thought of shooting it out of the rocket and all the jostling doesn’t seem that great. Just my opinion. Also – are you using your pistons with the bulkhead next to the charge – like “|_|” and not the other way?

Edward
February 20, 2008 at 4:41 pm #46942
Warren B. Musselman
Moderator
Both sides of a piston are subject to pressure changes due to deployment and therefore wouldn’t be an appropriate location for altimeters and other electronics.

Warren
February 20, 2008 at 4:57 pm #46943
mule
Participant
I had thought about the ejection part too, so I was trying to figure an alternate way to add the altimeter. But, not knowing much about ways to do it, I couldn’t come up with anything better. I had thought about using some expanding foam with a molded area in the center for the RRC2 to sit, the vent is a problem though. When it discharges from the tube, it will get a sudden blast of pressure if the vent is on top. If it’s on the side, I would have to use a sheer pin that is drilled through the center to keep the bay in line with the hole and gasses out. The sheer pin is Jeremiah’s idea, I thought of drilling it.

This is more of a temporary thing unless it works well. I have one of the Pico P1 altimeters coming that I can mount in the nose cone on the BB. The Sumo is destined to become a dual deploy and then the problem is solved.

I was going to run the piston with the bulkhead on top, that was the way both PML and Aerotech showed it. Is there alternate thinking on doing it this way? I’m all ears….. 🙂
February 21, 2008 at 1:37 am #46944
edward
Moderator
The way on the bottom is actually the correct method. The other method results in an unstable piston.

http://www.deltavrocketry.com/piston.htm

Edward
February 21, 2008 at 5:34 am #46945
Doug Gerrard
Participant
The way on the bottom is actually the correct method. The other method results in an unstable piston.

http://www.deltavrocketry.com/piston.htm

Sorry to disagree with you Edward but I’ve seen that site before and his theory, analysis and “tests” are all flawed. I think it’s a prime example of how misinformation can easily spread. Now I don’t put the bulkhead plate in my pistons at the top, but I do try to put them forward of the center point of the coupler tube.

Doug
February 21, 2008 at 7:11 am #46946
Tim Thomas
8) One good reason for putting the plate on the bottom is space. Often the space is limited and the plate on the bottom give you more room for shockcords and chutes. 8)
February 21, 2008 at 2:01 pm #46947
SCOTT EVANS
8) One good reason for putting the plate on the bottom is space. Often the space is limited and the plate on the bottom give you more room for shockcords and chutes. 8)

Good point, however I think the bulkhead pulling the piston scurt, instead of pushing, would be the way to go.
February 21, 2008 at 2:37 pm #46948
mule
Participant
Space on the Sumo may be an issue, but the Brant has more than enough room. Both pistons have the bulkhead set in about 1/4″ but hardly anything close to being centered.

I was talking to Jeremiah about something along these lines….

I feel it would be helpful to have some construction techniques stickeys on each of these “topical” threads. I don’t know how basic it would need to be, but something that walks a new builder through some “tips/tricks” that you guys use for builds. I know my way around a shop and have built about anything you can think of, but, ideas like this w/ the piston would never come to mind….. Kind of like using a spoon to mold the epoxy on a fillet…..
February 21, 2008 at 3:50 pm #46949
Warren B. Musselman
Moderator
Personally, I put the piston bulkhead right about the 1/2 way point in the piston. Additionally, my pistons are about 10% longer than the diameter of the airframe so that they can’t cock and jam in the airframe. Pistons are great and I use them on everything from 38mm up to 3″. Above 3″ I’ve never bothered with them although I know folks who use them up to at least 6″ airframes.

Warren
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