Military S-250 Shelter Conversion

rlrenz

Explorer
Back before I became an ambulance fan, I had decided to modify a military radio shelter into a unit that could be stuffed into a trailer, or into the rear of a pickup truck. Shelters come in many sizes, with the S-250 about the best for what I wanted to do. The 250 was designed to slide into a standard 8 ft pickup box, and I could also slide it into my handy-dandy utility trailer. They only weigh about 750 Lbs empty since they are a composite structure built from aluminum extrusions and foamed urethane panels. They have a layer of 1/8" wood bonded to the structure to provide a thermal isolation. The skins are thin, though - about 0.040", so you don't drill & tap for a screw, you use a Riv-Nut.

They are found in many versions - some have air conditioning, some are used with radio equipment, some are used for telephone systems, some have been modified into aircraft control towers - but all of them are solidly built, and can be powered with 120 VAC and 28 VDC. Power inlets are filtered to prevent radio interference as well.

They also come with a peep hole so the user can verify the identity of a visitor before the door is opened (more important in Vietnam than is North Dakota, probably...), and they normally also come with a rifle holder and a helmet hook.

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I was able to scare an S-250 shelter up that a friend of mine had purchased and wanted to sell. Like many of the shelters, it was originally used to house radio teletype equipment (RTTY). Nearly all the equipment was gone when I got it, other than an elderly teletypwriter and some support racks. The military had also de-militarized it with a sledge hammer, so light fixtures and other things had to be replaced. Somewhere along the line, a gorilla driving a forklift had harpooned the side as well.

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Once I got it emptied out, I tracked down copies of the appropriate manuals to see what I could learn. I found out that a side puncture was a common occurrence, and the manual explained exactly how to repair it. The light fixtures were replaced with a couple of trouble lights for a short term answer.
 

mhiscox

Expedition Leader
Thanks for starting this build thread. The S-250 and S-280 shelters, which cost the government huge amounts of money to purchase, are one of the best ways to get a heavy duty "cabin" at a low cost and ready made. The S-280s, for example, are a nice size (nominally 12' long x 7' wide x 7'high with 6'5" standing height) for an expedition truck.

Good luck with the project.
 

red EOD veteran

Adventurer
Solid portable shelters. Have a MUST shelter (basically an expandable S280) that I'll be building.

Are you still going to use the S250 now that you're an ambulance fan?
 

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Gatsma

Adventurer
I could see sliding one of these into a nice heavy-duty utility bed; would be one tough combo on the right truck...
 

rlrenz

Explorer
MNtal showed me photos of someone who was able to license a military Heavy Equipment Tractor as an RV - he removed the rear winches, and dropped an S250 into the pocket. That gave him an enclosure to modify into an RV.
 

rlrenz

Explorer
Thanks for starting this build thread. The S-250 and S-280 shelters, which cost the government huge amounts of money to purchase, are one of the best ways to get a heavy duty "cabin" at a low cost and ready made. The S-280s, for example, are a nice size (nominally 12' long x 7' wide x 7'high with 6'5" standing height) for an expedition truck.

Good luck with the project.
Expensive was an understatement - here's the tag that was still on mine when I got it:

DSCN3798.jpg

The only problem with any of the shelters is that they are made from relatively thin aluminum - about 0.040". Once you realize that the shelters have fairly heavy aluminum framing on specific spacing (19" for the S250), you can plan accordingly. When I installed 120 VAC receptacles in mine, they were on a 19" spacing. When I installed new LED ceiling lights, they were on a 19" spacing. Any where in between, you can use a Rev-Nut or even (GASP!!) a sheet metal screw - I used Riv-Nuts. When I installed a patch panel over the forklift attack-point, I used flat head pop rivets. Once you understand them, they are a very decent unit to work with.
 

Gatsma

Adventurer
MNtal showed me photos of someone who was able to license a military Heavy Equipment Tractor as an RV - he removed the rear winches, and dropped an S250 into the pocket. That gave him an enclosure to modify into an RV.
Man, talk about overkill; think he was afraid of breaking something?!?!
 

rlrenz

Explorer
Solid portable shelters. Have a MUST shelter (basically an expandable S280) that I'll be building.

Are you still going to use the S250 now that you're an ambulance fan?
No, the 250 is going to go down the road. After I retired, I found that I had arthritis, and bending to work in the 250 is a real pain (literally...). At this point, I have all the exterior problems repaired as per the MIL technical manual (kissed by a forklift = hole = panel repair), the interior is painted as per the MIL standard, the old power / phone inlet box has been converted to a circuit breaker cabinet, the exhaust fans have been rebuilt, and all new 120 VAC wiring has been installed using thinwall conduit. Tonight, I installed all new light fixtures - I was going to build fluorescent fixtures as per the MIL design, except they would hang down about 4" from the ceiling. Instead, I installed six 3-watt LED fixtures mounted on shallow conduit boxes. They put out an amazing amount of light, and only require 1.5 amps at 12 volts - TOTAL! Another reason I went with LEDs is that they are easy to dim, and the lighting system can be connected to a vehicle's 12 volt system as well (but doing the math, a battery with a solar cell to charge it would probably provide more than enough power). I'll get it painted OD in a few weeks, then it will be ready to move.

I've done enough research on the shelters, and enough work on mine, that I wanted to do a thread on it. You can do a Laurel & Hardy grade job on something, or you can do it the right way - I've seen some of the worst, but not too many that were done carefully and thoroughly. I have copies of the Technical Manuals, the MIL standards, and the test results from the development program. About the only thing I haven't managed to get are a set of the manufacturing drawings.

My ambulance will move indoors for the winter - here abouts, winter can get ugly at times.
 
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rlrenz

Explorer
Man, talk about overkill; think he was afraid of breaking something?!?!
Massive overkill, but we all have our fun toys - I found some photos of the creature - I don't have any information, other than it is an M920 HET. Take a look at the project, and you gotta admit that it is a very nicely done RV conversion.

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Overkill - YEP. Fun? YEP. Do I want one? No - My presently calm neighbors would probably get cranky.
 

Gatsma

Adventurer
I keep coming up with "invalid attachment" on all 5 pics - don't know if it's my computer or what..... oh well...
 

Gatsma

Adventurer
Oh MAN! Now THAT is a freakin' RIG! Not sure it'll fit a campground space though, but who's gonna tell him he can't, or shouldn't, do it?!?
 

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rlrenz

Explorer
That Rig belongs to Soni Honegger, besides the M-920 RV Soni also built the scorpion among other iconic 4x4's and ohv's. http://www.scorpion4x4.com/index.html

Do a quick google search on him he's had some interesting toys. :coffee:

Hijack off.
Not a hijack - but a help. I appreciate the info - I could find the photos, but I couldn't track down the source.

Definitely the biggest, baddest, rig that you would ever see in a campground - no matter where the campground is (top of a mountain, Death Valley, middle of a swamp - wherever it is doesn't matter). The only GOTTCHA I could see from a rig like that (other than parking, mileage, etc) is the cleanup that you could have to go through after a bit of mud. Many, many years ago, I was a construction engineer, and our site was several hundred acres on the flood plain. Every weekend, I'd park my truck on the driveway, with a garden sprinkler under it. After 4-5 hours, I'd drive it back onto the garage, leaving a pile of mud on the driveway.

Regardless, though, you gotta admit that with the mere addition of an S250 shelter, an "ordinary" truck has been turned into a truly all-terrain RV.
 
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