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My little Chinese BALLS 2012 Project

Posted: Mon Apr 23, 2012 7:19 am
by Passaretti
Here goes nothing ...

I don't know exactly why - but something lit a fire under my ass having watched the footage that came out of BALLS 2011. A few days later, I found myself in Dave's backyard workshop making plans for 2012. (I should note that Dave's trousers were smoking as well ...).

My general approach hasn't changed much since it's inception in the days that followed the news from last years BALLS. I'm not planning on setting any records or vying for any prize money. This is as selfish as it get's - I want to see if I can build and safely recover a N powered minimum diameter rocket in Black Rock Desert. This project represents MANY firsts for me ...

I've attached the update slides (sent earlier this year to the rest of the BALLS guys on this forum). Since then I have procured stock 6061 tube/plate for the first pass at the fin-can. I'm lining up a welder as we speak. I've also started toying around with gas release mechanisms for the recovery system. When GLR get's their site back-up on Tuesday, I'll be purchasing some filament wound coupler tube to build a stand-in for the CTI 6GXL motor, as well as the prototype recovery section (see slide 5).

Lot's to do - time is running out. I can't believe it's almost May! This project will be my primary focus from here on out.

Mike

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 9:03 am
by Scoop1261
Design looks good, concept looks sounds, motor choice is viable, your approach & attitude are commendable, your build skills are up to the task .............My vote is "Not a Snowballs chance in Hell!" :P :P Only because you have Tommy in your camp!

But then again ...... Neither is B2K12 either! :lol:

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 10:09 am
by Sumo310
Cool, should be a great flight, can't wait to see your updates to this thread.

Could you friction fit the motor to the fincan?? :P

Have you used the ARRD before? I like the design, but found it wasn't the easiest to use and a right PITA to keep from rusting, I've since moved to the DG Tether.

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 10:40 am
by Passaretti
Scoop1261 wrote:Design looks good, concept looks sounds, motor choice is viable, your approach & attitude are commendable, your build skills are up to the task .............My vote is "Not a Snowballs chance in Hell!" :P :P Only because you have Tommy in your camp!

But then again ...... Neither is B2K12 either! :lol:


Haha!!!!!!

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 10:50 am
by Passaretti
Sumo310 wrote:Cool, should be a great flight, can't wait to see your updates to this thread.

Could you friction fit the motor to the fincan?? :P


Actually - that's exactly what I was thinking! It's either this or some sort of reversible bond - possibly an adhesive up to the task that can be dissolved away later with acetone, etc. I'm also toying with the idea of heating the fin-can and cooling the motor casing (expand one contract the other) for a snug/slip fit. The idea is that when the temperature stabilizes the fin can would be clamping down on the motor. Not sure how well this process will work in reverse though ...

Ideally whatever I figure out will not involve modifying the motor ... however I am open to all options.

Sumo310 wrote:Have you used the ARRD before? I like the design, but found it wasn't the easiest to use and a right PITA to keep from rusting, I've since moved to the DG Tether.


I've been toying around with one for a few weeks now. Solid little gadget. We've used something similar for array deployments on satellites - http://www.tiniaerospace.com/pps/pinpullers.html. In my case for the ARRD, I do not intend to use it with BP. I have been experimenting actuating with compressed air & CO2 - zero clean-up. It works really well so far, but the true test will be in flight. I intend on testing the sh*t out of it this season.

Thanks for the comments - I look forward to hearing more from all you guys!

Mike

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 11:52 am
by rocket_troy
Sounds like an awesome project Mike! I'm sure there'll be plenty in this one for us all to learn something from. Good Luck!

TP

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 3:53 pm
by ogivemeahome
Passaretti wrote:... heating the fin-can and cooling the motor casing ...

You would most likely need some sort of interface between the two to minimise conduction. e.g. a sheet of mica?
some heat reflective coating? - only guessing. Shrink fitted parts tend to stay together unless they are of different materials (different expansion rates).

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 4:09 pm
by Scoop1261
Passaretti wrote: I'm also toying with the idea of heating the fin-can and cooling the motor casing (expand one contract the other) for a snug/slip fit. The idea is that when the temperature stabilizes the fin can would be clamping down on the motor. Not sure how well this process will work in reverse though ...



Getting the fin can on is the easy part! .......... Getting it off again....... well that's a whole nuther story!

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 6:06 pm
by Bourney
Possibly (probably) a dumb question but if you are getting a welder involved could you not machine up your own motor case and have the fins welded directly to it?

Perhaps too costly? It wouldn't be usable for any other project.

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 6:35 pm
by Scoop1261
Bourney wrote:Possibly (probably) a dumb question but if you are getting a welder involved could you not machine up your own motor case and have the fins welded directly to it?

Perhaps too costly? It wouldn't be usable for any other project.


............ And any welding would stuff up the heat temper process required to maintain the T6 rating, and you would need to re-treat the whole project.

Finding a freezer long enough to stick a 6GXL CTI case in is going to be difficult too I would assume ........ ????

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 6:37 pm
by drew
Just in case you haven't seen them, Aeropack is making minimum diameter motor retainers that look to be a good fit for your project.

http://aeropack.net/min_dia_retainers.asp

Granted the diameter would be identical to the motor casing so it wouldn't be prefect, but you get the idea.

I can't wait to see this thing fly!

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 6:40 pm
by drew
Finding a freezer long enough to stick a 6GXL CTI case in is going to be difficult too I would assume ........ ????


Come on... Mike's in the good ol' US of A. OF course he could find a freezer long enough to take a 98mm 6GXL case. The problem lies in whether or not there's enough space in the freezer given all the venison "collected" over winter.

Re: My BALLS 2012 Project

Posted: Mon Apr 23, 2012 7:02 pm
by OverTheTop
Finding a freezer long enough to stick a 6GXL CTI case in is going to be difficult too I would assume ........ ????


About a cup of liquid N2 would do the trick nicely! No freezer required.

Re: My BALLS 2012 Project

Posted: Tue Apr 24, 2012 6:09 am
by Passaretti
You guys are awesome. When I woke this morning and read all your posts - I thought to myself "Damn, if I go back to sleep and wake up in September maybe the rocket will be done by then ..." :)

I've given the fin/can attachment a lot of though over the past few months... Rather than get bogged down on something that is not going to help reach my goal (removing the fin-can from the motor casing) - I'm inclined to kick this can (w/ fins?) down the proverbial road ... at least until the motor casing comes in AND the fin-can is ready for a test-fit (or the only fit). Worst case, I can heat fit it and then cut it off after the flight.

Speaking of the motor casing ... I don't normally bash people on this forum - and I won't mention names but BLAKE NIKOLIC is falling short on all sorts of promises .... guess I shoulda' gave him that interview when I was in Queensland last November ... WTF Blakey?

:)

Some very exciting shots of the 6061 stock I am going to destroy trying to make my very first aloomineeum fin can with.

Mike

Re: My BALLS 2012 Project

Posted: Tue Apr 24, 2012 9:02 am
by air.command
This looks like a seriously cool project Mike! Definitely will be following your build progress on this one. :D

Passaretti wrote: Worst case, I can heat fit it and then cut it off after the flight.


What if you split the fin can along the root edge of one of the fins. Weld one fin along one edge of the split perhaps with a right angle bracket as well and then weld a right angle bracket along the other edge of the split. Then you can easily slip the fincan on the motor and tighten up a bunch of bolts along the right angle through the fin. If you tap holes in the fin (and perhaps the right angle on the other side) and use counter sunk screws you shouldn't incur a drag penalty. If you use enough bolts you should be able to tighten it so it can't come off and then you can take it off again when needed. Whether structurally it will take the load at Mach 3 is another question.

- George