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  1. #31
    Join Date
    7th March 2012
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    Discovery Bay, CA
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    154
    Killer project!!! Guess the next step is to build a motor mount and turn that thing into a land tracking cruise missile. Contracts to build those would likely be a little more lucrative. Nice work indeed! Thanks for sharing.

  2. #32
    Join Date
    20th September 2010
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    Toronto, Canada
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    167
    Quote Originally Posted by Windeavor View Post
    Killer project!!! Guess the next step is to build a motor mount and turn that thing into a land tracking cruise missile. Contracts to build those would likely be a little more lucrative. Nice work indeed! Thanks for sharing.

    Thanks. The next one is in the works; I'm going for an upscaled "Javelin" style projectile:

    -8.5" X 60" Carbon Airframe
    -Active roll stability, taken from my EVA 2 airframe
    -folding fins, to eliminate the Sabot
    -3D camera set up
    -Active air brakes, deployed at apogee by the AIM USB 2 Altimeters, to scrub some speed and get the descent parabola a little tighter.

    Air brakes have previously been tested on a 4" airframe, and work surprisingly well, as does the active roll stabilizer Here are some pics from those builds:
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    Last edited by Blackfly; 2nd April 2012 at 01:45 PM.

  3. #33
    Join Date
    13th February 2012
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    4,692
    What would provide the force necessary to keep the airbrakes deployed, or will they be oriented so that the drag holds them open?
    Temporarily potential impulse transformed into no-longer-potential-anymore impulse since 2013-01-01: A lot.

  4. #34
    Join Date
    20th September 2010
    Location
    Toronto, Canada
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    167
    For this application, I use Firgelli 12 V mini linear actuators(2), hooked to a mosfet relay circuit, triggered by an event channel(apogee) on the Entacore Altimeters. The brakes are then retracted using a limit switch that reverses polarity upon main separation & deployment, ensuring they are retracted before touchdown, to prevent damage & entaglment in the recovery system.

    VIDEO OF AIR BRAKE OPERATION

  5. #35
    Join Date
    13th November 2009
    Location
    Katy, Near Houston (still Texas, though)
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    3,115
    Quote Originally Posted by Blackfly View Post
    For this application, I use Firgelli 12 V mini linear actuators(2), hooked to a mosfet relay circuit, triggered by an event channel(apogee) on the Entacore Altimeters. The brakes are then retracted using a limit switch that reverses polarity upon main separation & deployment, ensuring they are retracted before touchdown, to prevent damage & entaglment in the recovery system.

    VIDEO OF AIR BRAKE OPERATION
    Über cool!



    Greg

  6. #36
    Join Date
    27th July 2009
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    CA and VT
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    344
    Quote Originally Posted by Blackfly View Post
    As for "VERA", well that's just plain cool. I'd love to know what he's using for a release valve. Some guys have been seriously talking about air starts from cannons, much like the old ARCAS variant launch system. Any thoughts on this?

    Patrick
    I know the guy who had this cannon built (through a forum, not in person). It was a military contractor research project, and a pet project of his. The canon is powered by a propane/air mix. The release valve is a really really thick piece of metal with a few score marks on it. The chamber is prepressurized to a few atmospheres of pressure, has the stoichiometric mix of propane mixed in, and ignited. As the fuel burns, the pressure increases until it is enough to rupture the metal burst disk, releasing the incredibly hot gases into the barrel.

    Any other questions?
    In space, no one can hear your shutter click.

    LUNAR and CRMRC L1

  7. #37
    Join Date
    20th September 2010
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    Toronto, Canada
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    167
    Quote Originally Posted by Lentamental View Post

    Any other questions?

    Yeah, do you have any contact info for him??

    PT

  8. #38
    Join Date
    27th July 2009
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    CA and VT
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    Quote Originally Posted by Blackfly View Post
    Yeah, do you have any contact info for him??
    Honestly I haven't been on that forum in a few years so can't find my login info that you need to access the user info.
    Here is the post he made about VERA over at SpudFiles: http://www.spudfiles.com/forums/vera...un-t23989.html
    His username is D_Hall. If you make an account you should be able to private message him and find out more.
    In space, no one can hear your shutter click.

    LUNAR and CRMRC L1

  9. #39
    Join Date
    4th April 2012
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    5
    Quote Originally Posted by Blackfly View Post
    Yeah, do you have any contact info for him??

    PT
    Vanity searches take people to interesting places, don't you think? So how may I help you?


    PS: The next time you see Bob Fortune, tell him "hi" for me. Haven't spoken to him in about 10 years, but it really is a very small world.

  10. #40
    Join Date
    20th September 2010
    Location
    Toronto, Canada
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    167
    That's awesome! I was hoping to learn about your valve & air supply system, to pass on to the "Chunkers" I met in Delaware. You should definitely attend a Chunk event, or at least say hello on one of the Chunkin' social network pages. You're like a GOD to these guys.

    I'll make sure to say hello to Bob, the next time we speak. Please keep developments on the VERA posted here, its an incredible piece of kit!

  11. #41
    Join Date
    4th April 2012
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    5
    Quote Originally Posted by Blackfly View Post
    That's awesome! I was hoping to learn about your valve & air supply system, to pass on to the "Chunkers" I met in Delaware.
    Well, as stated previously in the thread, my valve is nothing more than a burst disk. It's not sexy, but it's very effective.

    As for air supply, I use a trailer mounted 140 CFM Ingersol-Rand compressor but VERA was built such that the air compressor isn't critical. I could run it off a 5 HP "wheelbarrow" compressor with the only impact being rate of fire.

    You should definitely attend a Chunk event, or at least say hello on one of the Chunkin' social network pages. You're like a GOD to these guys.
    I'm not sure how useful my system is the the Chunkers. I break just about every rule they've got (I use combustion, I use sabots, I don't use ASME certified pressure vessels).

    My only comment to those who would follow in my footsteps is this: While VERA is in many ways just a scaled up potato gun, be advised that combustion does not scale linearly. Detonation is a very real possibility if you don't take steps to avoid it (I have).

    Beyond that, I've never actually managed to find an active Chunker board. Back when VERA was in the design phase I thought such might be a useful resource but all I was ever able to find was a couple boards that were busy for the week or two after the nationals (or whatever they're called) discussing results... And that was about it. So if such boards are out there and *active*... I'm not opposed to dropping in to answer some questions, but I've no idea where they are; they need to not hide so well.

  12. #42
    Join Date
    20th September 2010
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    Toronto, Canada
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    167
    Yes, the chunkers are a quiet bunch; even more so than rocketeers. I think the question everyone wants to ask is.... Can we build an air start rocket, and tube launch it with the VERA??? What a spectacle for one of the big Rocketry events.

    If anything, it makes for some good "techie" discussion, and I thank you for posting on my thread.
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  13. #43
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    4th April 2012
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    Quote Originally Posted by Blackfly View Post
    Can we build an air start rocket, and tube launch it with the VERA??? What a spectacle for one of the big Rocketry events.
    With VERA? No, for reasons that range from engineering (her barrel only elevates a few degrees) to finances (who's gonna pay for it?) to legalities (read: liability). That said, an air start of a gun launched rocket is totally doable.

    Long, long ago, I did it myself. Granted, my attempt was very crude and done on the cheap, but I proved what I wanted to prove.

    I'm also aware of another guy who did it with a roughly 40 mm x 1000 mm rocket but my google fu appears to be weak at the moment and I can not find him.

    However, something tells me that you're on the lookout for something a bit more spectacular. I suspect a (vertically mounted) VERA clone is a bit out of your logistics and/or price regime so putting on my thinking cap for a moment....

    You'll want to go with a hybrid design. Pure pneumatics on a large scale simply become too cumbersome, in my opinion. Plus, they're absolutely limited to Mach 1. I mean, if you're gonna build it, why not shoot for supersonic?

    Throwing some numbers around...

    6" bore x 20' long barrel. Large enough to be useful. Small enough to be affordable and easy to transport (yes, "affordable" and "easy" are relative terms).

    8" x 72" combustion chamber.

    3" burst disk.

    That'll launch a 25 pound projectile to just over 500 ft/s and give you a clean air start at well over 1000 feet AGL.

    And it'll be pretty loud.



    edit: On the other hand... If you've a fair chunk of change... As VERA demonstrates, much can be done.
    Last edited by D_Hall; 6th April 2012 at 06:00 AM.

  14. #44
    Join Date
    23rd September 2011
    Location
    Tx.
    Posts
    747

    Wow!

    That's very impressive sir thanks for the share I knew there was more cool stuff out there besides rockets..as for "vera" well that's just plain kewl rockets,pumpkins,projectiles AND blowing stuff up

  15. #45
    Join Date
    21st March 2012
    Posts
    2
    The electric winch, used for the projectile down the draw of 100 feet long barrel. When the projectile / sabot combo was about 44 "long, I had guns in muzzleloaders, most pants." Punkin Chunkin "were only about 14" X8 "We shot a ball without synthetic 1/8" winch cable from the drum, then mounted on the back of the hoof. Attached to the winch on the cylinder head, we used a wireless driver into force, the design of the shoe easily and quickly in the long run.
    .

  16. #46
    Join Date
    4th April 2012
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    5
    Nah, I don't do muzzle loading (at least, not for largish guns). VERA is a break action.
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  17. #47
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    20th September 2010
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    Toronto, Canada
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    167
    Thats a great set up; is that bolted up for each shot? Or is there some kind of ram/jack to secure the breech?

    PT

  18. #48
    Join Date
    4th April 2012
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    5
    Quote Originally Posted by Blackfly View Post
    Thats a great set up; is that bolted up for each shot? Or is there some kind of ram/jack to secure the breech?
    There's a ram/jack to position the barrel in the open/closed orientation, but it's not expected to hold through actual firing. For firing... Yeah, we bolt it up for each shot. It's not as bad as it sounds though. Impact wrenches make quick work of it.

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