Making a one-off custom tank
 

Any suggestions on the products and process to make a one off, lost-mold, custom tank?
I'm assuming you could carve and sand the tank shape out of foam, allowing a little clearance and some gentle radiused corners. Then split the foam block and hollow out most of it. Reattach the pcs then cover with Kevlar twill weave cloth and epoxy. Once cured, open a hole for the main fuel fitting and melt away the foam using acetone, spending time to really get the foam residue out.
I've worked with carbon fibre cloth and fiberglass, but never kevlar.
Any input or suggestions? Or is this not really a wise do-it-yourself project, and smarter to just send the foam blank to Gary at JetTech to make the tank?

RE: Making a one-off custom tank
 

Correct me if I am wrong, but i was under the impression the Kevlar is to improve the burst resistance of the tank in a crash. I have seen many tanks that are just made of fiberglass so I wonder if this is really necessary. I have seen a couple videos of guys laying glider wings with Kevlar and they treated it just like fiberglass, no real special procedure.

RE: Making a one-off custom tank
 

I built two for my Avonds F-15 Kevlar is a ***** to work with. I used vacuum bags to do it. All Kevlar is good for is the bursting and it will not tare. But in a crash it will leak as bad as fiberglass. I had the Kevlar so that is what I used. In the future I will just use fiberglass.

RE: Making a one-off custom tank
 

Sean, I've made some A-7 tanks. I did not use kevlar, don't know that its really necessary. Kevlar does work just like regular cloth, but can be difficult to cut.
I have Kevlar shears that I use, when working with it.
I made foam plugs, covered them with Ultracote, then waxed and PVA'd them before covering with glass. I bought these rings from
Todd: http://dreamworksrc.com/catalog/mach...rt-p-1426.html
And also bought the Sullivan stopper kit, this way I can open it up to clean, etc.
Jim

RE: Making a one-off custom tank
 

Thanks for the feedback guys. Jim as you used monocote and PVA does that that mean you cut the tanks off and then had to join and seal up the halves? I was hoping to just create it in one pce. I guess multiple layers of fiberglass would be easiest to work with and have more flexibility laying it down around tighter curves.

RE: Making a one-off custom tank
 

I've done several, and always used plain old fiberglass. In an impact, the kevlar bursts just as easy as glass does...
I make a one piece blue/pink-foam plug, make sure your corners are rounded. I make it 3/1 to 1" longer than I need, so that it can be cut into two pieces. Cut the plug into two, 1/8-3/16" longer than you want the big part to be. I wrap several layers of masking tape around the cut end of the short piece to make an offset for a flange. I cover the whole thing in SolarTex, which is a really low heat film, then wax and PVA the plugs.
lay up the glass (I use a layer of 2-ounce, then a layer of 6 and another layer of 2 ounce - just because that has worked for me before). When cured overnight, I take a VERY thin spatula (ask your dentist for a CoeSoft mixing spatula) and get the lip open, then put several drops of water in the open area and pop up the sides. If it won't slide off, I use a football filling needle on my compressor, give a squirt and make sure that you catch the plug before it flies across the room. I like to use BVM's fittings.
A trick told to me is to then wash and acetone the inside of the tank, then flow fresh epoxy around the inside to fill pinholes that will happen in the corners (I also do the outside) then trim and assemble the two parts of the tank with Hysol or Aeropoxy. Make sure you pressure/leak test!

This has worked for me, and gives a plug for future use/ screw-ups.

Greg

RE: Making a one-off custom tank
 

Greg, thanks for taking a moment to post your experience. Do you have any pics of your process or results? Thanks!

RE: Making a one-off custom tank
 

I posted a how-to thread on making foam/econocote fuel tank molds (and tanks) several years ago. Let me see if I can make the search function work well enough to find it.

RE: Making a one-off custom tank
 

The search function really sucks, but I finally outsmarted it. :D

Here is the thread:
http://www.rcuniverse.com/forum/m_13.../tm.htm#132449

RE: Making a one-off custom tank
 

Boy I remeber that MB-339! Incredible engineering that you did on that plane Kevin! Was any of the structure original?

I look at those old threads versus the new age "build threads" you see these days......well lets just leave it at that!!

RE: Making a one-off custom tank
 

I actually have something "new" in the works right now. I will post a thread when I get a little further along with it. :D

RE: Making a one-off custom tank
 

Several threads already existent. Search.

RE: Making a one-off custom tank
 

Thanks Kevin for the link. A decade old and still relevant. Nice.
Started gutting my airframe today and it appears that the jet tech nano tank is almost an exact size to what I was going to create so I may just go with one of those.

How helpful. :eek:

RE: Making a one-off custom tank
 

Hi Sean::)

I never used Kevlar, I think that not is necesary, I use epoxi and fiber glass and add color to the epoxi (yellow) the tanks look prettys, I think. I make the master in blue foam and them I cut it in the middle, them I cover the master with brown tape and cover with 4 layers of fiber with epoxi with a few of micromix for get a epoxi more heavy. Them I remove the fiber withow brake the master.

You can see the tanks of my Bandit (withow color) and Bobcat (with color)

Here you see how I cover the foam with fiber with yello color:

https://picasaweb.google.com/1085696...63454551619538

BR from Spain.;)
Carlos Márquez.
_________________________________
http://cmjets.blogspot.com.es/

RE: Making a one-off custom tank
 

Good input Carlos, thanks. Can you still see the fuel level with the painted yellow?

RE: Making a one-off custom tank
 

I had this one saved http://www.rcuniverse.com/forum/m_91..._1/key_/tm.htm

RE: Making a one-off custom tank
 

Hi Sean::)

Yes, you can see the level of fuel because the tank not is completely opaque.

BR from Spain.;)
Carlos Márquez.
__________________________________________
http://cmjets.blogspot.com.es/

RE: Making a one-off custom tank
 

Hi again::)

Here you have another tanks made for me, for Boomerang and Salto sailplane, for smoke.

BR from Spain.;)
Carlos Márquez
______________________________________
http://cmjets.blogspot.com.es/

RE: Making a one-off custom tank
 

As I work with designing stuff in CAD enviorment I feel more comfortable doing it the high tech way with CAD software and a 3D printer :-)

For my 286mph Swist.

http://img855.imageshack.us/img855/4...0213162533.jpg

http://img825.imageshack.us/img825/3...0228135000.jpg

[youtube]http://www.youtube.com/watch?v=9r8h_YKh4So[/youtube]


For the old Twinjet.

http://img37.imageshack.us/img37/574...8zed201206.jpg

http://img651.imageshack.us/img651/5...9zed201206.jpg

http://img220.imageshack.us/img220/4...4zed201206.jpg

RE: Making a one-off custom tank
 

Recent lost foam method tank made over the last few days - 7 layers of 80g cloth

marcs

RE: Making a one-off custom tank
 

Henk

That is just brilliant, love the contoured tank for the foamy.

Mike

RE: Making a one-off custom tank
 

Below is picture of toughest molding job I have attempted. Contoured tanks to take advantage of space available and tank also serves and air ducting to the engine. I previously made one tank out of kevlar and decided it is not worth the extra work.
First picture is tanks right side up, rear view
Second Pic is tanks upside down side view
Third pic is tanks upside down rear view

RE: Making a one-off custom tank
 

very cool, hgow tuff is the printed material?