e-bay questions - Northern Colorado Rocketry

This topic has 13 replies, 6 voices, and was last updated 17 years, 8 months ago by mule.

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April 23, 2008 at 4:28 pm #40217
mule
Participant
First what I’m working on:
Vertical Assault, 3.0, two RRC2-minis w/ 2 pole rotary switch, Christmas light bulb charges, the lg removable plastic pins for mounting to BT.

I have been reading about having one large port instead of 3 or 4 small ports, this seems to make sense to me. That is actually why I have the system set up with the rotary switch. BUT, I am concerned about getting gases into the e-bay from between the bt and e-bay and if this is just a poor design in the first place. Or, should I ad a ring and use it for the port?
April 23, 2008 at 5:12 pm #47565
edward
Moderator
If you want to add a ring this is what I did on my L1/2 rocket. I wanted a 3/8 bulkhead so I took two pieces of 3/16. I used a rounding router bit and used it on one edge of each of the rings. When I put them together it was a groove for an o-ring. I used that on top and bottom to seal it off.

Edward
April 23, 2008 at 5:12 pm #47566
MikeS
Moderator
Most of the reading I had done indicated more than one. So I
let majority rule. I put three.

It has worked every time. On two, three inch rockets and
twice on a five.five.

I watch a lot of rocket DVDs and a lot of videos over the net.
Looking close, most have more than one.

😯 ?
April 23, 2008 at 5:51 pm #47567
mule
Participant
I liked the idea of having a port to stick a screwdriver through to turn on the electronics. I can probably put a few holes in it and still have a large enough one to get a little screwdriver into it.

Edward, that’s a good idea. I might try to add a ring on either end for a seal. Or just make a notch in the existing bulkheads for a thin ring.

Thanks
Greg
April 24, 2008 at 2:59 am #47568
Bruce R. Schaefer
It’s all according to our experiences. On my GLR VA, my favorite rocket along with the one to the left, I used one port. It worked. One to the left, I used 3, but it was bigger. But three are good, too, for the VA. This is the learning process. I used my beloved GLR VA on both L1 and L2 certs. You made a great choice. 😉 BTW, gases through vent ports are negligible. The VA comes with the nice O-ring for the bottom of the avionics’ bay. If you want to add one on the top, cool. Do what Ed said. Either way you’re good.
April 24, 2008 at 3:35 am #47569
James Russell
when I first started using electronics I was told that it is best to use 1 or 3. I have used 1 or 3 on 3in AF’s and usually 1 on anything smaller. Most of the E-Bays I have made for 3in works out to be 3 holes at or a little bigger then 1/8. if you take a small pocket screwdriver it will fit in an 1/8 hole but some of them have a flair right were the flat part starts, if it does the you can grind it off to match the shaft and it will fit. There are other things you can do as well but I think there is as many rocketeers.
April 24, 2008 at 4:22 am #47570
Bruce R. Schaefer
What James said. Make your port(s) the correct size, and grind that screwdriver down. A jeweler’s screwdriver works. You can get those in really small sizes. There are so many ways to do this it’s amazing. There is no wrong way… unless it doesn’t work, and that’s the learning process. 😉
April 24, 2008 at 7:36 pm #47571
mule
Participant
Bruce,
Did you use removable pins to hold the ebay in place or epoxy the sleeve into the VA? I was planning on using the pins so if I do another 3″ rocket I can use the bay in it too.

I’m off today, so I’m going to try and get it finished up. I’m heading to the garage to make a ring cutter for my router table like Mike B’s….. That DC20 is going to fit nicely in that cone. This is the way I redid the unit. I used epoxy to hold the antenna base in that position and re soldered the wire. I’ve only tested it to about a mile so far, in houses.

here’s the DC20 now.
April 24, 2008 at 10:04 pm #47572
Bruce R. Schaefer
By “sleeve,” do you mean the coupler? If so, I epoxied mine in, because I wasn’t going to use it in any other rocket. If you use pins or nylon screws to hold the e-bay section into the main chute airframe, MAKE SURE they don’t shear when the ejection charge goes off! I just used 1/16″ polystyrene on my nosecone, but 2-56 shear pins would work, too. Go bigger on the part you DON’T want to separate. Ground test before you fly.
April 24, 2008 at 11:21 pm #47573
Anonymous
I’ve used PML rivets to hold ebays in many (many MANY) times. They work great.
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