Updated the ol' Laweano to use a catapult system we discussed in the discord. The catapult system has a few advantages over the old basket system:
- it requires less mechanical precision, eliminating a source of difficulty or expense
- it secures the projectile much more securely in the weapon
- it allows for lighter weapons overall, as the barrel doesn't have to be larger than the projectile in diameter and the clamps don't have to be heavier than the basket.
- it allows the projectile to spin up if we're using rifling.
- it can take more punishment without jamming or breaking and requires less maintenance.
A Quick Primer on the PACT Method of Firearms Propulsion
During the years following the beginning of the Homeland War, many significant advances were made in the field of refocyte firing mechanisms, most notably the refocyte propellant cap mechanism (RPC) and the refocyte pusher plate mechanism (RPP). Pusher plate operated guns, in particular, possess three important advantages over more conventional projectile weapons:
1. They are almost completely silent, save for the sound of the pusher plate making contact with the round, both due to the lack of discharge gasses coming out of the firing chamber and the subsonic nature of the rounds.
2. They allow for caseless ammunition, as the propelling force is imparted upon contact with the refocyte plate within the firing chamber.
3. They are incredibly compact compared to conventional firearms, with current models only as long as a standard carbine.
However, the pusher plate mechanism is limited by poor muzzle velocity and the subsequent low penetration of conventional rounds. This is mainly due to inefficiencies during kinetic energy transfer between the plate and the round, as the energy discharge happens over a short but significant time interval. Higher power rifles utilizing special refocyte jacketed ammunition have been explored as a solution in the past, but delays during fire and the high purity required of the refocyte used remain significant issues in their full adoption.
Pulsed Acceleration and Continuous Transfer (PACT) methods have thus generated interest due to their promise in attaining far greater muzzle velocities than possible with the basic RPP mechanism while minimally interfering with its other advantages. This is accomplished by using a low-capacity refocyte platelet and keeping the projectile and the platelet in contact during the projectile’s travel within the barrel. Energy for the platelet is syphoned from a kinetic battery and discharges at fixed time intervals, as the platelet’s maximum capacity is exceeded, thereby providing the acceleration for the round.
The result is a powerful, compact weapon effective anywhere between medium and long standoff ranges which could utilize existing rounds of both conventional make and the special jacketed variety, as needed by the operator. Rounds fired by PACT methods would be, by their very nature, less quiet than RPP-propelled rounds in flight due to their supersonic speeds, but would be quieter than conventional arms by a large margin (30-40 dB) and lack the characteristic muzzle flash associated with chemical propellant based ammunition. What’s more, PACT methods uniformly benefit from lower-purity platelets, drastically reducing the refocyte cost of any weaponry that uses them in comparison to RPP guns.
The Catapult Longitudinal Rail PACT Configuration (“Catapult Longpact | Carapact”)
In the Carapact configuration, the projectile is clamped in place by way of a guiding ‘catapult’ which can engage two parallel rails in the barrel of the weapon. When the trigger is pulled back, a metal spring-loaded striker provides the initial push for the mechanism into the barrel. As the catapult engages the refocyte rails, the platelet at the base of the clamps is charged in a short period of time, while the acceleration jerks the bullet – triggering a pulse of acceleration. This continues for the length of the barrel, with the rails either interfacing with or acting as the weapon’s kinetic battery. Upon reaching the end of the rails the catapult stops and the projectile flies out of the weapon along a ballistic trajectory. Upon slamming into the end of the rails, the catapult is sent backwards into the chamber by small refocyte recoil pads, regenerating a small portion of the batteries’ energy, and another round is extracted by a metal tooth from the magazine, if one exists, and secured in the chamber via the clamps.
If no mechanism is in place to prevent subsequent fire, the platelet, having already been charged due to absorbing energy from the recoil, is triggered by the firing pin and fires again automatically, assuming the trigger is held down. By varying the length of the rails, the purity of the platelet, and the geometry of the weapon, it is possible to engineer a wide range of possible muzzle velocities and rates of fire.
The Carapact configuration should be mechanically simple to manufacture, given it doesn’t require large amounts of mechanical precision in any of its components, and allows the projectile to spin up in the barrel if rifling is present as it is free to engage any grooves (since the catapult is embedded in the weapon).
M1939 120mm “Laweano” Longpact Field Artillery Piece
While the Inithari Army Fellowship had previously operated a number of foreign artillery pieces, no special effort was made to implement refocyte operated field guns as the refocyte propellant cap mechanism, dominant at the time, had vastly inferior ranges to conventional pieces and was more capable in a howitzer role. Even when naval guns were first drafted, regular propellant charges were used in lieu of a dedicated refocyte drive system to foster a competitive range. Prototypes produced in the 1910s verified these findings and refocyte-driven weapons larger in diameter than 20mm were deemed impractical.
Since the arrival on the Harren islands, there has been renewed interest in the field of refocyte-driven large caliber guns (in part due to the high percentage of engineering staff coming from the Refocyte-smith Fellowship). The adoption of a 50mm RPP gun in the G2 Alanui, while proving mediocre when using conventional rounds, showed refocyte-driven guns had a future on the battlefield. The prototype tanks, in particular, highlighted certain advantages of these weapon systems tied to both increased ammunition loads, safer ammunition storage and the potential for much more rapid-fire with significantly less recoil than conventional guns of a comparable role. Soon thereafter, proponents of the catapult longpact configuration (headed by the inventor of the PACT method, Nikau Manawa) set out to develop a standard field artillery gun with a maximum range of at least 20 kilometers, a vertical arc of fire from 0° to 70°, a variable muzzle velocity in either notched increments or a continual interval, a projectile in the 30 kg mass range, and capable of being mounted on a rubber-tired towed mounting.
The new gun design is to use a 5 meter L41 barrel fitted with two parallel rails running down its length and lying on the horizontal axis and a catapult ring around them. The rails, known as the leads, are attached to a lever mechanism allowing them to be pulled further into the weapon, thus reducing the exposed lead length with the same effect as a lighter charge in a conventional artillery gun (variable muzzle velocity and thus range), as well as allowing for the leads to be replaced upon expenditure – to be recharged or recycled. The piece is breech-loaded with a lock that opens and closes the breech in a single movement of a lever. The ammunition for the gun is caseless, consisting purely of the shell, and is rammed directly into the firing chamber, where the catapults clamp it in place and are ready to engage the starting position. The firing hammer is implemented as part of the locking mechanism and is actuated by a continuous pull of a firing lever on the side of the gun assembly, at the gunner’s position.
Ramming the shell home is followed by notching the power lever by a given amount, as required by the range, with the kinetic energy varying with lead length in increments given on the side next to the lever position (leading to theoretical maximum range of 25.7 km for a 30 kg projectile at 40° going at 800 m/s, given that’s the muzzle velocity I’d personally cut it off at; assumind Cd = 0.4, h = 500 mm). Once the range setting is set, the leads are locked in place and the firing mechanism unlocked. When obtaining a firing solution, the gunman can quickly calculate the weapon’s range given the use of a manual and the marked mass of the projectile. An experienced crew should be capable of performing this process roughly 17–20 times per minute, if not more, owing to the shorter procedure and smaller weight of the shells used in comparison to conventional cannons of a similar role.
The “vee”-shaped split-trail lower carriage features an integral two-wheel axle and a four-wheel limber supporting the trails for transport (with two wheels per trail, near the end), and houses the suspension for the gun piece. The upper carriage includes the gun cradle, which connects the gun assembly to the upper carriage; gun plate, the side frames for the bearings, pintle-mounted seats for the operators, and the azimuthal and elevating gearing that make up the traversing mechanism. When not in use, the gun’s trails can be brought together and locked up so as to be moved manually by the crew or towed by a Wikiwiki transport car.
Despite the piece being capable of firing any shell that'd fit within its breech, High Command insisted shell types be listed. Production lines for 120 mm AP, HE, Smoke and Refocyte shells are to be made operational for the weapon. Given these shells are already in use with the army in multiple roles, this isn't a major innovation where the design is concerned, but needed to be mentioned.