Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin (Account/Technical Issues)  |  Contact Global Moderator
September 17, 2021, 10:11:00 AM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1]   Go Down
Print
Author Topic: Foam b25 glider  (Read 1245 times)
0 Members and 1 Guest are viewing this topic.
Donanton
Copper Member
**

Kudos: 0
Offline Offline

United States United States

Posts: 3

Topic starter


Ignore
« on: August 13, 2014, 10:43:21 AM »

Hi everyone

I've always enjoyed, and I'm sure you have too, the giant foam gliders that you could get any reasonably sized store during the summer.  Now being as I have the tools and time to design my own, I want to convert the Royal B-25 D Mitchell into a glider.  Pretty much take the overall shape, make a mold, and use some 18X expanding foam from smooth-on to fill the mold cavity.

Has anyone here had experience doing this?
Logged
lincoln
Titanium Member
*******

Kudos: 38
Offline Offline

United States United States

Posts: 2,518



Ignore
« Reply #1 on: August 13, 2014, 12:54:02 PM »

No, but I've read a couple of stories of expanding foam continuing to expand long after it was applied. Suggest making in thin layers and exposing to elevated temps for a while, and maybe a bit of humidity, depending on the chemistry of the foam you're using. A hollow shell might be a good idea, as that fuselage is going to have quite a bit of volume. Probably a good idea to do a sample pour to figure out the density of the material you're using. My impression is that the mixed foam is quite a bit heavier than the bead foam those gliders are usually made of.

If you're only going to make one, you might consider carving and sanding it out of Highload 60 or Plazamate foam. The density is a bit over 2 lbs per cubic foot, and they can be sanded very smooth if you use fine enough paper. They can be wet sanded, so dust doesn't necessarily have to be a major issue. A further advantage is that no one will be clamoring for you to do a pour from the mold for them, which you might expect if your project turns out nicely! ;-)

If you do make a mold, an alternative way to use it might be to heat up some foam sheet very evenly and pull it into the mold with vacuum or push it with pressure. Much like the usual vacu-form process. I haven't done it myself, but at a job long ago I modified the design of some parts that were made this way from "structural foam", which is much heavier. If I'm not mistaken, the following ultrasound cart has the lower sides formed this way and is a close relative of the model I worked on:
http://mesl-usa.com/UltraSoundEquip/1.1.png

There are a lot of threads about scratch built foamies over on RCGroups.com

Sounds like a fun project. Keep us up to date!
Logged
Donanton
Copper Member
**

Kudos: 0
Offline Offline

United States United States

Posts: 3

Topic starter


Ignore
« Reply #2 on: August 13, 2014, 02:24:27 PM »

It has begun.  I'll post pictures later, but I have begun cutting out the 1st (body joint), 4th 5th 6th(wing bend by engine), 8th and 11th(last wing rib) ribs to make the first wing.  I've yet to decide what thickness skin I will use, perhaps 1/8" (the same as the rib thickness.)  This along with the fact that I will seal the wing after sanding it and that I will apply many thin coats of the female mold parts should stop the wing from warping at all during the mold making process.

Now I just need a small scroll saw.  Off to cash converters!
Logged
Donanton
Copper Member
**

Kudos: 0
Offline Offline

United States United States

Posts: 3

Topic starter


Ignore
« Reply #3 on: August 21, 2014, 08:18:50 PM »

I have a picture.  It's the ribs (1,4,5,6,8,11) for a wing.
Attached files Thumbnail(s):
Re: Foam b25 glider
Logged
Pages: [1]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!