Making it airtight ! - RC Groups
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Mar 01, 2013, 08:06 AM
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leroyo's Avatar

Making it airtight !

Hi all,

I always meet the same problem when I mold one piece fuselage for my dlg; leak.
I use clown balloon that I need to stretch and I attach them to the stem (Always use 2 balloons) with adhesive tape and a piece of latex (tubing).

So I just wonder how do you attach the end of the balloon on the stem to avoid leaks. Pictures of what you do are welcome.

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Mar 02, 2013, 03:05 PM
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Ward Hagaman's Avatar
I tried some paintable latex from the craft store for sealing the ends of my bladder (I used latex tubing) and it worked really well. You have to wait a few hours for it to dry, but it worked perfectly.
Mar 02, 2013, 08:45 PM
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Jim.Thompson's Avatar

2 Balloons?

How do you use 2 balloons? One inside the other?

When I experimented (unsuccessfully) with balloons as an inflation bladder, I tied the end to a short length of vinyl tube with a rubber band twisted between multiple turns. Then, the short length was plugged into the next size up vinyl tubing which went to the air supply. I was only using aroun 15 psi of pressure.

I could not get then to last the duration without bursting, so went back to welded plastic inflation bladders, tied the same way as above - without leaks.
Last edited by Jim.Thompson; Mar 02, 2013 at 08:46 PM. Reason: spelling
Mar 04, 2013, 10:21 AM
Registered User
Last week I molded my first pod without having any issues with leaks. The difference was that I switched from welded bladders to clown balloons. I used a combination of two peoples' techniques to get no leaks. I used Tom Siler's technique of inflating the balloon and "rolling" it back over the coupling to the stem. Then I used DLGJunkyard's technique of wrapping a second balloon very tightly around the base of the stem to seal it well. It's a little hard to explain, but I can post pictures tonight.
Mar 04, 2013, 02:54 PM
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Here's roughly what I do: It is a bit easier now though since I've moved up to the Qualatex 260 balloons. They go on the stem easier.

Mar 04, 2013, 07:58 PM
Registered User
Here's a pic. I inflate the balloon and slide it over the stem with the help of a tiny bit of vaseline. With the mouth of the balloon at the base of the stem I roll the balloon over the coupler and deflate it. Then I wrap a second balloon tightly around the base to ensure it's well sealed and to support the bladder at the point insertion into the mold so it can't bulge out the back and pop. Let me know if that doesn't make sense.

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