Author Topic: M111 Self-Propelled Anti-Aircraft Gun  (Read 3742 times)

Offline Rickshaw

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M111 Self-Propelled Anti-Aircraft Gun
« on: September 22, 2014, 08:32:45 AM »
The T249 Vigilante was a prototype 37 mm self-propelled anti-aircraft gun (SPAAG) designed as a replacement for the Bofors 40 mm gun and M42 Duster in US Army service. The system consisted of a 37 mm T250 six-barrel Gatling gun mounted on a lengthened M113 armored personnel carrier platform with a radar system.




The US Army was quite impressed with the performance of the T249 but however realised that the system had severe limitations in the form it was designed.  Treating the T249 as a "proof of concept" the Ordnance Board ordered that a better vehicle be designed to fix the problems encountered.  Perhaps the worst was the limited amount of ammunition which was carried onboard the vehicle, barely allowing more than three or four engagements before it had to be replenished.  Then there was the problem that the gun had to be reloaded from outside the vehicle, which was clearly unacceptable if it was operating in a Nuclear, Biological or Chemical environment.   While the radar was an excellent improvement over the vehicle it was intended to replace, the M42 Duster, which had none, it's range and discrimination was limited and it was felt a more powerful unit would be required.

In order to accommodate all those things, a larger, roomier vehicle than the M113 was required.  While it was possible to lengthen the M113 chassis, the M113 production was running at full speed, just keeping up with the existing orders for standard vehicles to re-equip the Army.   Casting around, the decision was taken to utilise the M109 Self-Propelled Howitzer chassis.  This was large and was readily and cheaply available.  So, the M109 was adopted.  A new belt feed ammunition supply was designed, using "cassettes" which could be easily loaded in and out of the large rear hatch on the vehicle.  With a crew of three (Commander, gunner and driver), carrying sufficient ammunition for 10 or more engagements and a substantially more powerful and larger radar, the M111 SPAAG was adopted into US Army service as the M111 SPAAG.

The vehicle depicted, is that of the first M111 SPAAG which was presented to the Press on 7 June 1966.  It was later deployed to Europe where it made a valuable contribution to deterring Communist aggression from the USSR on the German border.   The value of such vehicles were proved when several, supplied to Israel, successfully defended the Dimona nuclear reactor against an unsuccessful Iraqi air attack in 1991.  Several MiG-23 aircraft were downed, described as having been "shredded" by the firepower of the 37mm Gattling guns.












The Model

The model is a venerable Italeri M109 SPG, with suitable modifications.   The gun was what held up the build for some time as I attempted to work out some way in which to produce consistent circles and hexagons (and drill them well enough, without splitting) to hold the gun tubes, made from brass tube.   The radar aerial is from Shapeways and intended for for a 1/16 scale U-boat.  It is a little large but I think looks quite good.  The 3d printed material though, proved to be difficult to paint, basically sucking in the paint applied (which was acylic) so I sealed it first with a weak solution of PVA glue which seemed to stop it.   The vents are Gundam vents, from HLJ, suggested to me by Gingie.  The acquisition radome came from the top of a large, multicolour pen. 




« Last Edit: September 22, 2014, 06:04:29 PM by Rickshaw »

Offline elmayerle

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Re: M111 Self-Propelled Anti-Aircraft Gun
« Reply #1 on: September 22, 2014, 08:45:44 AM »
Beautiful!!  That really  looks the business!!  I could see that easily happening.

Offline jschmus

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Re: M111 Self-Propelled Anti-Aircraft Gun
« Reply #2 on: September 22, 2014, 08:48:41 AM »
I see lots of potential for this one. Jungle clearing in Vietnam. Urban pacification in the Sandbox. The possibilities are endless. Good show!
"Life isnít divided into genres. Itís a horrifying, romantic, tragic, comical, science-fiction cowboy detective novel. You know, with a bit of pornography if you're lucky."-Alan Moore

Offline LemonJello

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Re: M111 Self-Propelled Anti-Aircraft Gun
« Reply #3 on: September 22, 2014, 08:13:44 PM »
Very cool! Really looks the business.

Offline buzzbomb

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Re: M111 Self-Propelled Anti-Aircraft Gun
« Reply #4 on: September 24, 2014, 04:25:50 AM »
Really nice work on that, prior to reading about it here, unknown  variant stream.

Offline Frank3k

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Re: M111 Self-Propelled Anti-Aircraft Gun
« Reply #5 on: September 24, 2014, 05:07:31 AM »
It looks really good, especially the gun.

One tip with Shapeways - if possible, only have items printed in their "Detail Plastic" or "Frosted Detail". The resolution is higher and cleanup is much easier.
The nylon ("Strong and Flexible") and sandstone are cheaper, but porous. Instead of using PVA glue, use an auto primer. It will (eventually) fill up the porous surface, leaving you an easy to smooth finish. On my first nylon print, I went through half a can of Mr. Surfacer, before I stupidly realized that I could use a cheaper auto primer. If the part is small enough, just dunk it in a can of primer and let it soak it up.

Offline Brian da Basher

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Re: M111 Self-Propelled Anti-Aircraft Gun
« Reply #6 on: September 24, 2014, 07:06:38 AM »
The radar dish really makes this one for me!

Most excellent!

Brian da Basher

Offline Rickshaw

  • "Of course, I could be talking out of my hat"
Re: M111 Self-Propelled Anti-Aircraft Gun
« Reply #7 on: September 24, 2014, 08:57:34 AM »
It looks really good, especially the gun.

One tip with Shapeways - if possible, only have items printed in their "Detail Plastic" or "Frosted Detail". The resolution is higher and cleanup is much easier.
The nylon ("Strong and Flexible") and sandstone are cheaper, but porous. Instead of using PVA glue, use an auto primer. It will (eventually) fill up the porous surface, leaving you an easy to smooth finish. On my first nylon print, I went through half a can of Mr. Surfacer, before I stupidly realized that I could use a cheaper auto primer. If the part is small enough, just dunk it in a can of primer and let it soak it up.

Thanks.  I found the watered down PVA glue worked quite well, sealing the printed plastic and stopping it sucking in the paint.  I don't have auto-primer but I did have PVA glue.  :)

Offline Feldmarschall Zod

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Re: M111 Self-Propelled Anti-Aircraft Gun
« Reply #8 on: September 25, 2014, 06:50:01 AM »
Great looking triple AAA Rickshaw.  With the Shapeways parts, I found that washing the mold release agent off of them helps as well.
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