MX - CobaltWolf/Bluedog-Design-Bureau GitHub Wiki
Peacekeeper/MX Missile (Paxus) derived rockets
Peacekeeper is a very high thrust rocket that will flip if not flown properly. Pitch over should begin right away after launch, ending at 65-75 degrees before hitting mach 1 (around 3000 meters), then follow the prograde marker keeping the angle of attack at a minimum. The second stage should be hot-staged at first stage burnout. Once above 25000 meters deviation from prograde should be safe. If a coast will be used before third stage ignition, the vessel should be returned to prograde again or it will tumble while still in the atmosphere.
Athena's Castor 120 first stage is derived from the Peacekeeper SR-118 first stage, with the significant difference being the thrust, so the same part is used for both engines. When used on Athena the thrust slider should be set to 75% or as desired. This will lessen the dynamic pressure loads and permit more steering during ascent.
All of these rockets require RCS turned on for roll control. It is advisable to start with the RCS of your payload disabled so it is not being used during ascent.
Construction
The tags "mx", "minotaur", and "athena" work well to put the relevant parts on the pallet. There are 4 primary engines that are combined to make the two core stacks plus alternates. They are the dual role SR-118/Castor 120, SR-119, SR-120, and Castor 30. There is also a Castor 30XL, a related motor that is not used in the canon build for any of these rockets.
Peacekeeper, Minotaur and Athena each have a unique control unit that mounts below the payload fairing and provides at a minimum vehicle roll control. To keep the parts simple probe cores and communications are not installed, but they could be added with a simple module manager patch if desired.
Peacekeeper/MX Missile (Paxus)
A ballistic missile, the Peacekeeper was never an SLV, but it would be fine for that purpose. The first stage is the SR-118, second stage the SR-119, and third stage the SR-120. The fourth stage Post Boost Vehicle provides RCS for three axis control, and a small Liquid Fuel engine for insertion maneuvers or a little extra delta-V.
Minotaur (Pulgasari)
Minotaur is built from decommissioned Peacekeeper missiles. The first three stages are unmodified (but usually painted white instead of black), and the stage 4 Post Boost Vehicle is replaced by the Guidance and Control Assembly. The GCA consists of the Guidance and Control Module, an optional propulsion unit, and an interstage.
The Guidance and Control Module provides RCS for three axis control. The interior is hollow and can mount parts up to 0.9375m wide, such as a Star 48 or Super HAPS. There are two interior node positions, recessed and flush mount, and the variable height interstage part adds up to 0.8 meters of vertical space.
Athena (Minerva)
Athena is a whole new vehicle rather than retired missile parts. The first stage Castor 120 is a civilian variant of the MX missile's SR-118. Athena I uses a Castor 120 first stage, and Castor 30 second stage. Athena II uses two Castor 120's, and a Castor 30 third stage. Both are topped with the Orbit Adjust Module (OAM) which provides RCS for three axis control, and a very small four nozzle Monopropellant engine for minor adjustments.
The Castor 120's are tailored to the mission, so the engine thrust slider should be set for an appropriate acceleration on the first stage, and on the Athena II second stage. The Castor 30 stage uses a bell type thrust curve, with low initial thrust not reaching 100% until half fuel, then falling off again. The net effect is a slow buildup of acceleration for the first half of the burn, and somewhat steady acceleration the second half.
