Project Titan

Explanation of namesake

Project Titan is, in reality, a project series of two separate projects that succeed each other. Namely, the T57E20 “Titan 1” and the T57E20A “Titan 1A”. To quickly elaborate the reasoning behind the nomenclature of the name, the Titan is heavily inspired from a prototype tank designed for an American armored warfare convention in the 50s called the T57 Heavy. In compliance with the methodologies of tank naming at the time, this prototype was designated the T57 Heavy because of it’s completion in the year of 1957 and it’s classification as a heavy tank. The “E20” component of the name similarly follows this tradition, with the prefix “E”, commonly reserved for a design revisions, and the year in which the Titan project was commenced. Hence, T57E20. The Titan 1A similarly follows this logic with the addition of “A”, which is often used to signify a modification to the design. Hence, the T57E20A is a modification of the T57E20, which is in itself a revision of the original T57 Heavy.

Project Statement

A remote controlled, armored gun carriage which can serve the purpose of pest control and extermination in inaccessible or dangerous environments with a turret design inspired by the T57 Heavy. Other specifications include power supply redundancy, spaced composite armor, S-link tank tracks, and an electric drivetrain, full serviceability, and a fire control system compliant with government agencies for use without a license. In addition, this project will compose of a dominantly 3D printed construction and may not require specialized machinery to manufacture or assemble.

Design History: Turret

As mentioned above, the concept of the Titan 1 started with the T57 Heavy, and specifically, the turret. This turret design, unique to French autoloading tanks of the cold war and very few American prototype concept tanks, is equipped with a dramatic angle on the front facets, which contributes to a variable known as “relative armor thickness”, defined by the following equation:

RAT=NAT/cos(θ)

• RAT: Relative Armor Thickness
• NAT: Nominal Armor Thickness
• θ: Angle between projectile trajectory and normal of target facet

By the logic of this equation and with the created model for the tank head, the Relative Armor Thickness is 41% higher than the nominal thickness at its thinnest given the assumption of the turret oriented directly at the trajectory of an incoming projectile. This occurs at the section on either side of the gun, often referred to as the “cheeks” of the turret like the cheeks of a face, which is the part of the turret with the least nominal angle. With this knowledge, the aforementioned cheeks of the turret were thickened to reinforce the weak point of the turret, while minimizing the balance offset induced by the extra material and overall weight of the turret.

For gun traverse and elevation, two extremely compact AC motors were initially selected while attached to reduction geartrains. However, this design was heavily flawed due to the excessive underpowering of these motors and the gears of the geartrain being too small for bearings, thus producing excessive friction on the gun elevation. However, the low overall weight and well lubricated design of the turret ring allowed the turret to rotate, albeit with some difficulty. The power supply for the turret was conceived to be a AA battery, which would also serve as a counterweight for the turret to counter that of the main gun. However, this would inevitably prove to be insufficient of all cases.

Project Statement

A remote controlled, armored gun carriage which can serve the purpose of pest control and extermination in inaccessible or dangerous environments with a turret design inspired by the T57 Heavy. Other specifications include power supply redundancy, spaced composite armor, S-link tank tracks, and an electric drivetrain, full serviceability, and a fire control system compliant with government agencies for use without a license. In addition, this project will compose of a dominantly 3D printed construction and may not require specialized machinery to manufacture or assemble. Further modifications will include a “Top and Bottom” clamshell-like design to allow for the entire upper and lower chassis to be separated and exposed, an enhanced target Aquisition suite, a sufficiently equipped suspension system, and an FPV(First Person View) targeting system.

Design History: Turret

The first thing that was done with the turret was to scale it up to accommodate the size of the gearbox, which ultimately resulted in a scaling factor of 1.75:1. This scaling factor was utilized across the board on all design elements and had several knock-on effects, both positive and negative. The weight distribution drastically changed throughout the tank, shifting the center of mass radically forward. To accommodate this, the entire fire control system was retracted rearward, thus resulting in a more optimal weight distribution. However, Due to the newly formed cavity at the nose of the turret becoming a new weak point, for armor, it was entirely filled in with material, The model was iterated until the weight distribution was slightly rearward enough to allow for other components to finalize the weight balance.

The turret elevation gearbox was eliminated entirely, and the motor was replaced with a NEMA 17 DC motor. This allowed for both the holding torque and innate strength of this type of motor to be more than sufficient to both stabilize and actuate the elevator. The turret rotation mechanism was also overhauled, replaced instead with a traditional integral ball bearing track, into which 35 individual stainless steel balls were inserted into a track that would eliminate friction and resistance concerns. Another NEMA 17 was used, mounted to the underside of the deck, to engage with an integrated ring gear to actuate the turret rotation mechanism. Both motors were tested with a Creality Ender 5 control board and were proven to function effectively.

Other modules were later added to aide in target acquisition, including a separate 800mAh battery and green-dot laser, both of which were mounted to the two picatinny rails on the roof of the turret, immediately atop and behind the main gun. The gun was successfully test fired with through an analog trigger, but the FPV system was never tested beyond the green-dot laser for target acquisition.

Suspension:

The suspension and drivetrain subsystems were handled in parallel, although with a heavy emphasis on the suspension. This would be a mistake that is elaborated on later in this section.

The suspension system was conceived as a torsion-style suspension system, invented in WW2 by Germany and later employed by every nation on earth for it’s simplicity and effectiveness through to modern day. Very simply, torsion suspension employs the elastic material properties of a metal like steel to allow for suspension travel for heavy vehicles. My version of this suspension system relied on that concept, but also employed the criticism of this system noted by a Youtuber who formerly served in the Canadian Armored Corps, specifically with the dangerous and difficult task of servicing this system. My solution was to invent a modular and adjustable suspension system that can be installed with a single, through running screw that also acts as a structural element to the otherwise 3D printed module. In effect, provided a simple pair of pliers to orient the torsion module, the torsion bar can be slid through the pair of support bearings and be screwed securely into place quickly and easily. This system worked perfectly in early testing, but when the heavier modules, such as the turret with the firing and targeting systems, were added, it became subject to frequent breakdowns, specifically in the torsion module.

The specific anatomy of the torsion module is superficially elementary, but required extensive calibration to determine the optimal idle position to ensure maximum travel distance of the suspension bougie, ideal spring strength and number, and prevent overextension upon de-loading. In addition, due to the spatial constrains of the torsion module, the side walls are relatively thin and are prone to catastrophic failure due to splitting at the layer-lines. My solution to this was to, with a medical syringe, fill the cavity between the inside diameter of the torsion module and the outside diameter of the spring coil with Titebond II Wood glue. This drastically increases the surface area by which pressure is applied from the springs to the module, and therefore increases the loading capacity of the module before which layer splitting takes place.

The suspension bougies themselves were a unique element that held a number of unique challenges. In particular, it was evident early on in assembly that PLA, the chosen material to manufacture the tank, did not have the elastic strength to maintain its’ form under load. This resulted in a situation where they bowed outward from the chassis, which resulted on excessive stress and wear on the inner edge of the wheels, which in tern resulted in some instances of the wheels breaking at that edge due to forced layer shift and separation. My solution was to take an example from material composites, specifically reinforced concrete. In this aforementioned example, concrete is an outstanding material for resisting compressive forces, but poor at withstanding flexural and tensile stress. To complement this, rebar is used to resist these tensile forces, and complement the concrete by resisting flexural forces. In this analogy, the concrete is the PLA bougie, and the rebar is a 7071 Aluminum plate that I cut to the profile of the interface between the two halves of the suspension bougie, sanded to create a surface that will accept adhesive more readily, and glued between the two halves of the bougie with Titebond II. This effectively solved the flexing problem, and eliminated it from further instances.

An S-Link style tank tread system was created from scratch with some influence taken from the MCRV mine clearing variant of the American M1 Abrams, but the wheel and idler setup were derived directly from the original T57 Heavy. There was an initial issue with the tank treads ‘walking’, or detracking, but a 10mm 30-degree chamfer was able to simply and effectively remedy this issue. However, the excessive weight of the tracks themselves caused the front idler sprocket and rear idler sprocket to be torqued in their mounts due to either track weighing nearly 12lbs each, in part due to the approximately 250 M4x80 screws, 250 M4 nylon locking nuts, 500 track pads, and 750 track links that compose either track. This was remedied by reinforcing both the interior and exterior faces of the hull of both sprockets, as well as the redesign of the front idler axle.