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SCOTT EVANS.
SCOTT EVANS.-
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Bruce R. Schaefer
Okay, next project… simplify the Avionics Bay. I have two 48″ pieces of 5″ PR G-10 tubes that will be joined in the middle with an Ebay, bottom end will have the booster–this time not so zipperless because I’ll be attaching the booster harness to the motor casing. With PR tubing and a long harness (50-60′), should have no zippering problem, ideally and luck withstanding. The upper section will be screwed to the Ebay with six 6-32 screws. When the main shoots out from the upper section, from the top, it will be connected to the 12″ long Ebay section via 3/8″ screws and 5/16″ U-bolts, with the booster attached at the bottom end, dangling 50-60′ below, above, or equal to it. That worked before for me. No biggie. The only problem I’m having at this point is screwing on the upper section to the Ebay, which leaves a chance of ejection gases escaping from the coupler seal. Granted, ground testing will give me what I need. Worst case, I’ll just epoxy the Ebay to the upper section and deny myself easy access to the upper charges. Last time I epoxied the coupler to the upper section. This time, as I said, I want to have access to the charges for the main, just six screws away. Last time, I used 6 switches… 3 for primary, 3 for redundant: one power on, the other two their respective charges. I just want to use two switches for this next one. It’s an L to N rocket; total weight should be under 40 pounds. I want to use a certain key switch that only I’ve used in the past. It will be exposed, but the metal around it is no lower than the business end. I mean, I’ve blown the booster under this switch up and the section above on two separate occasions, with J and K loads. It never lost continuity. I feel confident that it will continue to perform well at a higher level. I’ll be cutting a 2″ section of the upper section to use as the Ebay center to hold the key switches. Any thoughts or horror stories? All would be appreciated… especially before I dedicate this project one way or another. 😉 Thanks, guys.
Conway Stevens
Bruce can I recomend what I do for all my ebays. I make them all removeable. Easy to acess and easy to install. I also would recomend using at least #8-32 screws to hold it in place. Did you ever see my build thread on TRF of Full throttle. you should look it over and see what you may be able to borrow from that to your design… Let me know if you need any other help or suggestions…
Here is the link to the build thread…
http://www.rocketryforum.com/showthread.php?t=27663&highlight=constevens
Bruce there are alot of pictures to see what I did and how I went about building it. I think there is some stuff there to help you on the ebay and how to seal it as well as how to fasten it in place.
Conway
Bruce R. Schaefer
Do I know about your L3 link? Please, what do you think got me to L3? 😉 I’m just looking for opinions. I’ve had some PM’s that are leading me back to my L3 techniques so far. I’m so glad you put that link back up. I think Scotte needs to visit that. Scott, that will answer a lot of questions.
Anonymous
IMHO there is a “best of both worlds” solution that is way hard to explain via forums or email… Next time on the range I can show you what I do, anyway. The short version is this – I epoxy the coupler into the upper section, leaving enough hanging out to act as the coupler… I then drop the top bulkhead in from the fore end and the backplate from the aft end, holding it all captive with eye nuts http://www.bosunsupplies.com/products2.cfm?product=S0322 and a piece of allthread.
By doing this, there are no screws to lose, you have 100% access, there is no drag from exterior screws, etc. It is also very, very strong. Of course I’m interested in as little drag as possible, and this design gives me that. I also have total access to everything. Works for me, anyway…
SCOTT EVANS
Id like to see a picture of the whole thing.
scotte
Conway Stevens
I would agree with JW on that if its a altitude rocket and your going for records or as high as could.. Then dont use external fasteners. Im on my way out the door now and have some other design and thoughts to share that I would also use. Some im sure similar to Johns and another that I havent seen used here at all.. But I will share that later…
Conway
Bruce R. Schaefer
I used JW’s way on my L3, and it worked fine. Conway, I’d be interested in what you have to say.
Scott, if I could post pictures, I would. You could see what I did. PM your e-mail to me, and I’ll send some.
Bruce R. Schaefer
Scott, here are some good sources for Ebay info.
http://www.vatsaas.org/rtv/construction/avbay/avbay.aspx
http://www.giantleaprocketry.com/hpdefault.asp
http://www.info-central.org/recovery_dualdeploy.shtml
This last one uses a slide switch. Never do that. Even mounted horizontally, the forces at work on a rocket can make the slide turn off.
http://www.info-central.org/construction_antizipper.shtml
This last one is Info-Central, a pretty good information site. I put you on the anti-zipper section. The index is on the left, browse through and see what they have to offer. Besides all the knowledge in this club, I also recommend Mark Canepa’s 2nd book on HPR. Looks at it from the certification point of view.
SCOTT EVANS
cool
Bruce R. Schaefer
Most of us use MWC’s switches. You’ll find those on Jim Amos’ site: http://www.missileworks.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=MWC&Category_Code=cat060
Bruce R. Schaefer
Conway Stevens
Anonymous
SCOTT EVANS
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