R/C Tank Combat

Rocket Launcher #RL001

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Type: M20 Rocket Launcher Armament: 3.5in HEAT Rocket
Built: Sept 2012 Armor: None
Builder: Mike Lyons Rating: 1/1
Status: Operational Battles: 8
Owner: David Lyons Points Earned: 13,372
Call Sign: Bazooka Joe Points Given: 2,000
Notes:
 
  • First muzzle-loaded, single-shot asset
  • C12C controller
  • Hitec HS-311 servo-controlled elevation and rotation
  • Spyder Imagine electronic marker
  • Dimension Engineering PicoSwitch trigger control


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    Early in the Korean War U.S. forces found the 2.36 inch projectiles of the M1 and M9 series "Bazooka" rocket launchers were ineffective against the heavy armor of the T-34/85 tanks supplied by the Soviet Union to North Korea. The newly developed M20 "Super Bazooka" with a 3.5 inch HEAT round was rushed into service and proved very successful. I chose it for this project because I wanted some type of shoulder-mounted rocket launcher and a .68 caliber paintball is reasonably close to the 1:6 scale of the action figures.

    Here is Pfc. Joseph Gumm on his first day in action with the M20. It can be fired while standing, kneeling, sitting, or prone, but the kneeling position always comes to mind when I think of shoulder-fired weapons.

    Lieutenant Cy Kotic's last order before he was fragged was "Hold this position at all costs!" so Joe stays rooted to this spot, only moving enough to face the enemy from any direction.
     

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    It's a rocket launcher, but it's not rocket science!
    I wanted an asset of my own for A Bridge Too Far but time was short, so I knocked this up in one day. Total build time was around 5 hours, some of which was spent trying complicated solutions for a simple problem.



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    "Gentlemen, we can rebuild him.
     We have the technology.
    "
    Oscar Goldman
      in The Six Million Dollar Man.

    In his first tour of duty Joe stepped on a land mine. After breaking off the right arm at the shoulder and the right leg at the hip, a 7/8" long-barrel hole saw in a drill press made short work of this 12-inch action figure.

    The barrel is a 10-inch length of aluminum tube with an internal diameter of 0.68". The paintballs from my local shop fit it perfectly - it takes just a little force to push them down the tube, and they fly out nicely. The vertical feed piece is a length of 3/4" size copper pipe.
     

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    The tube and pipe are joined with epoxy. The rear portion is sealed with a cork from a sherry bottle. Inside the tube around the forward edge of the hole (to the left of the pipe as shown here) I piled up a ridge of epoxy about 1/8" high to act as a ball detent. A paintball is inserted from the muzzle end and pushed down to the detent with a 1/2" inch diameter rod.

    The copper pipe supports what's left of the body of the action figure. The right arm and lower right leg are attached solely by the clothing. The hands go together nicely to hold the trigger piece ... eventually.
     

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    Image from www.mcmaster.com

    This is the critical component of this unit. It's a flexible 90-degree elbow that takes 3/4" OD pipe at each end. One end is attached to the copper pipe and the other to the sawn-off barrel of the paintball marker. Unlike garden hose this device doesn't crimp very much when bent a little - I only need 10 degrees forward and back.

    This thing really grips smooth surfaces and the copper tube is 7/8" OD so I applied Vaseline to the inside of each end to enable easy insertion (and removal for maintenance). I was concerned there might be some reduction in pressure but in practice it shoots paintballs about as far as the other assets and they break reliably.

    This is the initial mock-up of the internal layout. It worked very well in my shop and I was short on time so I just added a piece of foam sheet between the tank and the marker and took it to the battle for A Bridge Too Far. The box is a simple octagonal "hatbox" made from 3/16" sanded ply. The 9 oz CO2 tank is horizontal which will probably feed liquid if the tank is more than half-full - I'll replace it with an upright 4 oz tank later. The marker is positioned so that the PVC elbow is just below a cutout in the lid. The hose clamp on the left is just hanging loose at this point so I don't forget to put it on before inserting the copper pipe.
     

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