Overview

The Hermes 2 motor uses our new propellant (Cherry Limeade) and a more advanced internal geometry. It is a P9000 motor, constructed from 3 grains, cast in K-Mac Plastics Canvas (CE) Phenolic tubes, inside liners from the same source and materials. For a roughly constant 3000 lb thrust curve, one finocyl grain and two BATES grains are utilized. The finocyl grain, located at the nozzle end, is 12.5 inches long with a core diameter of 2 inches and .75 inch long fins, .375 inch wide fins. The next two forward grains at 27.5 inches long and 30 inches long, with 2 inch and 1.75 inch core diameters, respectively. The grains are bonded into the liners by a polyurethane glue. The liner is inside of a 1/4 inch wall 6061-T6 aluminum tube. The forward closure is retained by eight 5/16 inch radial bolts into an aluminum ring. It is sealed between itself and the case using two -354 o-rings, and between itself and the liner using one -351 o-ring. The aft closure is a single piece, with eight 5/16 inch bolts threading into itself. The aft closure additionally serves as a nozzle carrier. Two nozzle inserts, one of graphite and the other linen (LE) phenolic  graphite nozzle insert is glued with high temperature room temperature vulcanizer (RTV) into the aft closure. Two -354 o-rings seal between the aluminum aft closure and the case. No seal is enforced between the aft closure and the liner so as to prevent the liner from becoming a pressure vessel. Additionally, a tapered boattail is attached to the end of the aft closure using eight 1/4 inch bolts for an enhanced aerodynamic profile.

Key features:

• Ammonium Perchlorate Composite Propellant; 7.5% Aluminum; 82.5% Solids

• 70 inches of characterized propellant in three 5.125” outer diameter grains of varying geometry to balance regressivity (finocyl) and progressivity (BATES)

• Phenolic liner and casting tubes; bonded to liner with polyurethane; one liner splice

• Stepped cores to mitigate erosive burning.

• Parameters (as calculated in Burnsim 3.0):

Hermes 2 burnsim file from January 19th 2019:

3G.bsx