R/C Tank Combat

Rocket Launcher #RL003

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Type: M20 Rocket Launcher Armament: 3.5in HEAT Rocket
Built: August 2016 Armor: None
Builder: Mike Lyons Rating: 1/1
Status: Operational Battles: 1
Owner: Mike Lyons Points Earned: 1,000
Call Sign: Len Opie Points Given: 1,000
  • Spyder TL-R Marker
  • XL timing belt rotation
  • Servo pushrod elevation
  • Servo trigger

  • Click Photo For Enlargement (37 KB)
    Regarded by many as Australia's deadliest soldier,
    Leonard Murray "Len" Opie served in the New Guinea campaign in World War II, the Korean War, the Vietnam War, and the UN mission observing the India-Pakistan border.

    In Korea he led a team of six in an assault on a well-fortified enemy hill. Using six different weapons he was the only member of the team still standing (with a minor shrapnel injury) when the hill was taken, and later was awarded one of only five DCMs earned by Aussies in Korea.

    He rose through the ranks to earn a commission and retired as a major after serving as head of training for the CIA's Phoenix program.

    Photo from https://www.awm.gov.au/collection/148151/

    I have not yet found direct evidence that Opie operated the 3.5 inch "Super Bazooka" on which this asset is based but he was proficient with a wide range of weapons and during his service in Korea his unit [3rd Battalion, Royal Australian Regiment (3RAR)] used it.

    Photo from https://www.awm.gov.au/collection/146733/

    Click Photo For Enlargement (54 KB)

    Click Photo For Enlargement (29 KB)
    The design is based on the battle-tested original rocket launcher RL001.

    An 18"x18" octagon of 23/32" sanded plywood is covered with a self-adhesive floor tile and supports a 60 tooth XL pulley which protrudes through a 4 inch hole in the platform floor.

    A 6"x6" ball bearing turntable supports the platform floor which is a 15" circle of 15/32" sanded plywood.

    For this asset I wanted to try a belt-driven rotate mechanism.

    I found a 3D-printed 10 tooth XL pulley and ordered 5 (which turned out to be fortuitous as I ruined three during initial testing). The spline has 25 teeth and Futaba doesn't have a continuous rotation servo but Parallax has one that includes a very handy adjustment to remove "creep" (slow rotation when the transmitter stick is in the center position).

    To avoid spinning out the spline recess in the small pulley yet again I coated the recess with epoxy, inserted the spline and tightened the screw, and allowed it to set in place (keeping the spline facing downward throughout this process to keep epoxy out of the servo). This worked well, lasting throughout the first weekend of battle.

    A Check-It Uni-Mount is used to connect a 4 oz CO2 tank*. I have used two Uni-Mounts and both have given me problems so they will be replaced.

    Spyder markers use M8 metric threads on gas hoses so a male-to-male NPF-to-metric adapter allows a "standard" 1/8" NPT hose to connect to the marker.

    * It seems the Extreme Rage 4 oz tanks are no longer available, but Sodamod has a comparable unit.

    Click Photo For Enlargement (70 KB)

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