R/C Tank Combat

Tank #T100

Index   Edit

  Page 1 of 3 >> >| 

Type: Semovente 105/25 M43 Armament: 105mm
Built: 2013 Armor: 75mm
Builder: Frank Pittelli Rating: 40/4
Status: Operational Battles: 16
Owner: Frank Pittelli Points Earned: 30,440
Call Sign: Bassotto Points Given: 19,500
  • Leaf spring suspension
  • Molded TTS track & sprockets
  • Scooter Motor main drive
  • Aluminum lower hull
  • Carbon fiber upper hull

  • Click Photo For Enlargement (40 KB)
    The Semovente 105/25 tank destroyer was built by the Italians during WWII by mounting a 105mm gun on a tank chassis. Only thirty of them were built before the Italians surrendered. It must have been a very useful platform, because the Germans took all of them and built another 60 through the end of the war. As such, it must be considered one of the best armored vehicles built by Italy.

    My real reason for building the Semovente was the sheer complexity of its suspension. As shown here, each suspension assembly (there are four of them) consists of 8 wheels arranged on two triangular trucks that pivot in pairs. Each pair of trucks can also travel up/down, supported by a massive set of leaf springs. My goal: model the actual suspension as closely as possible.

    Click Photo For Enlargement (183 KB)

    Click Photo For Enlargement (119 KB)
    After prototyping various pieces of the suspension assembly (sometimes more than a couple prototypes were needed), I finally got the geometry I wanted, while still being able to build it. John found the caster wheels on-line for me. The trucks are aluminum, the swing arms are stainless steel and the leaf is spring steel.

    Making leaf springs is a little tricky. You have to heat them enough to bend them, but not so much that they are no longer springy. Once again, trial-and-error helped me zero in on the construction process. After welding the attachment pieces on the ends, I bent the ends toward each other using strong line and then heated the spring with a torch in the areas I wanted to bend. Eventually the leaf simply "popped" into place, giving me the desired shape.

    Click Photo For Enlargement (115 KB)

    Click Photo For Enlargement (155 KB)
    Here's all of the parts (minus lock-washers) that are needed for a single suspension assembly (multiply by four for the whole vehicle). Almost 100 parts per assembly, but each can be put together in a couple of minutes using just a pair of 7/16" wrenches and a hex driver. The "T" brace (shown bottom center) from which the entire assembly hangs was welded to the chassis.

    After two months of development and production, the suspension is almost complete. All that remains is to weld the "T" braces to the chassis (hopefully in perfect alignment) and add more leaf springs to each stack (after the first field trials).

    Click Photo For Enlargement (121 KB)

    Click Photo For Enlargement (141 KB)
    Here's the collection of prototype parts developed to figure out the suspension design. Despite having worked in the software world for over 30 years, I still think it's better to design-by-prototype. Not only does it help you simplify things, but there's nothing like drilling a hole in the wrong place to help reduce stress!

    Compared to the suspension, everything else seems pretty straight-forward. Cut some aluminum sheets to form the lower hull, add some 5/8" axles for the drive wheels, build some strong motor mounts for the scooter motors and attach the suspension assemblies. The red structures shown in the hull are steel tubing supports to which the assembly suspensions are welded. The steel tubes are then bolted to the aluminum hull. The suspension and hull sides can be removed as needed.

    Click Photo For Enlargement (185 KB)

    Click Photo For Enlargement (228 KB)
    The scooter motors are mounted on aluminum plates, which are then bolted to the bottom of the hull. Bearing blocks are mounted to the mounting plate as well. This allows them to be worked on outside the hull without losing axle alignment.

      Page 1 of 3 >> >|