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  • July 24, 2021, 02:10:02 AM

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Author Topic: 1/2 A profile proto - how to install a bladder tank?  (Read 394 times)

Offline Dennis Toth

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1/2 A profile proto - how to install a bladder tank?
« on: July 08, 2021, 08:02:47 PM »
OK, after several attempts to replumb my original tank I find that re-soldering an old edge is requiring more solder then the whole tank weighted. From other posts, 1/2A profile proto doesn't restrict fuel delivery systems to suction. So a simple bladder seems to be the way to go. Question, since it is a profile how does one secure the bladder so it doesn't flop around and come off during flight? Photos would help.

Best,   DennisT

Offline Motorman

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #1 on: July 09, 2021, 05:21:41 PM »
I made a streamlined fiberglass pod and glued it under the wing.

Did you get the PM I sent?


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Offline Mike Hazel

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #2 on: July 09, 2021, 06:25:55 PM »
Not very fancy but easy to do..........  Use a section of rocket body tube and fuel proof it.

Offline Dennis Toth

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #3 on: July 10, 2021, 06:00:02 AM »
Mike,
I was thinking of that, could also use part of a nosecone to finish it off front and back. My problem is space to install, seems most of the bladders expand to 1/2" or so and I need to be around 3/8". Might need to go back to a hard tank arrangement.

What is the bladder tubing size that expands the least?

Best,  DennisT

Offline Mike Callas

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #4 on: July 11, 2021, 02:19:56 AM »
How about an aluminum cigar tube? Very light ~ 1/2" diameter. And each tube comes with a treat inside.

Offline Dennis Toth

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #5 on: July 11, 2021, 10:24:08 AM »
Mike,
I did a search on eBay for them and there are lots out there. My problem is they all seem a little to large in diameter to fit under my wing. If I can find bladder material that will inflate to about 3/8" ish I could make a tube from 1/64" plywood and use the rocket nose cones for end caps. Who has 1/2A bladder material?

Best,   DennisT

Offline Dennis Toth

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #6 on: July 17, 2021, 06:32:58 AM »
In Dale Kirn's article for the Lil Pronto (American Modeler, Sep/Oct 64) he shows a hard tank and a soft balloon tank. The balloon tank (attached, might need to enlarge to see details) is not inflated like a bladder, just used as a soft fuel container. He said to squeeze all the air out then fill without inflating so that when the filler is remove no fuel comes out. Seems this then just collapse as the fuel is drawn out by the engine. I think one could do this type of non-pressure soft container by using fingers from a large vinyl or other type of glove. This way you could see fuel/air in the fuel sac and get out the air. I think this would fit in almost any shape holder like oval shape, smooth wedge or round and sit on the side of the fuse nicely. I intend to try this on the test block and see how the whole thing works. If anyone has used this approach please post your experience with it.

Did a little search and the RC pylon and combat guys have been using this type tank for quite a while it is called a Bubbless fuel tank system.

Best,    DennisT
« Last Edit: July 17, 2021, 07:33:41 AM by Dennis Toth »

Offline Motorman

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #7 on: July 17, 2021, 09:09:34 AM »
Of course a competition 1/2a proto needs to have a pressure fuel system. Balloon tank won't cut it. What engine do you have?


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Offline bill bischoff

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #8 on: July 17, 2021, 12:16:23 PM »
Melvin Schuette's mbsmodelsupply.com has small bladder tubing and fittings.

Offline Dennis Toth

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Re: 1/2 A profile proto - how to install a bladder tank?
« Reply #9 on: July 18, 2021, 11:10:40 AM »
I was reminded of the "little red nozzle caps" from a Q on Barton site. These are like finger protectors but smaller and used to roll onto the end of clack tubes to seal them after use. They are available from ACE Hardware (and eBay, Amazon) about $6 for a 10 pack. Should be just the right size for 1/2A with low/med pressure.

Best,   DennisT


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