Rocket motor with concentric propellant structures for shock mitigation
A solid rocket motor includes a first solid propellant and a second solid propellant at least partially surrounding the first solid propellant. The second solid propellant is resistant to fragment impact and the first solid propellant has a higher impulse than the second solid propellant.
1. A solid rocket motor comprising:
a first solid propellant and a second solid propellant at least partially surrounding the first solid propellant, wherein the second solid propellant is resistant to fragment impact and the first solid propellant has a higher impulse than the second solid propellant, wherein the rocket motor has a diameter, and the second solid propellant has a total diametric thickness, as a percentage of the diameter, of 5% to 20%, and the first solid propellant includes nitramine solid oxidizer and the second solid propellant excludes any nitramine solid oxidizer, wherein the first solid propellant has a composition:
Constituent
Trade Name
Function
Nominal wt %
Flake Aluminum
Aluminum
Ballistic
≤0.5%
Modifier
Lead Citrate
Lead Citrate
Burn Rate
2-5%
Modifier
Cyclotetramethyl-
HMX, <3
Solid energetic/
45%-65%
enetetranitramine
micron
gas generator
Nitrocellulose
NC
Energetic
0-2%
Binder
Trimethylolethane
TMETN
Energetic
10-20%
trinitrate
Plasticizer
Butanetriol
BTTN
Energetic
10-20%
trinitrate
Plasticizer
R-18 Polyester
R-18
Binder
4-6%
Polycaprolactone
PCL
Binder
2-4%
Nitrodiphenylamine
2-NDPA
Stabilizer
0.5%-1.0%
N-Methyl-P-Nitroaniline
MNA
Stabilizer
0.5%-1.0%
Hexamethylene diisocyanate
HMDI
Curative
.5-2.0%
and the second solid propellant has a composition:
Constituent
Trade Name
Function
Nominal wt %
Flake Aluminum
Aluminum
Ballistic
≤0.5%
Modifier
Lead Citrate
Lead Citrate
Burn Rate
2-5%
Modifier
Nitrotriazolone
NTO
Solid energetic/
45%-65%
gas generator
Nitrocellulose
NC
Energetic
0-2%
Binder
Trimethylolethane
TMETN
Energetic
10-20%
trinitrate
Plasticizer
Butanetriol trinitrate
BTTN
Energetic
10-20%
Plasticizer
R-18 Polyester
R-18
Binder
4-6%
Polycaprolactone
PCL
Binder
2-4%
Nitrodiphenylamine
2-NDPA
Stabilizer
0.5%-1.0%
N-Methyl-P-
MNA
Stabilizer
0.5%-1.0%
Nitroaniline
Hexamethylene
HMDI
Curative
.5-2.0%.
diisocyanate
2. The solid rocket motor as recited in claim 1 , further comprising a migration barrier between the first solid propellant and the second solid propellant.
3. The solid rocket motor as recited in claim 2 , wherein the migration barrier includes a polymeric layer or a metallic layer.
4. The solid rocket motor as recited in claim 1 , wherein the second solid propellant is resistant to fragment impact according to MIL-STD-2105D and NATO STANAG 4496.
5. The solid rocket motor as recited in claim 1 , further comprising a motor case in which the first solid propellant and the second solid propellant are disposed, and a nozzle disposed at one end of the motor case.
6. The solid rocket motor as recited in claim 2 , wherein the migration barrier includes a vinyl polymer.
7. The solid rocket motor as recited in claim 6 , wherein the vinyl polymer includes a solid carbon filler.
8. The solid rocket motor as recited in claim 2 , wherein the migration barrier includes aluminum.