S2-17 "Thoroughbred" Solid Fuel Booster

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S2-17 "Thoroughbred" Solid Fuel Booster
Part image
Solid rocket booster by

Radial size Large, Radial mounted
Cost (total) 9 000.00 Funds
(dry) 4 200.00 Funds
Mass (total) 70.00 t
(dry) 10.00 t
Drag 0.2-0.3
Max. Temp. 2200 K
Volume  ?
Impact Tolerance 10 m/s
Research Heavier rocketry.png Heavier Rocketry
Unlock cost 27 000 Funds
Since version 1.8
Part configuration solidBoosterS2-17.cfg
Solid rocket booster
Maximum thrust (1 atm) 1 515.22 kN
(vacuum) 1 700.00 kN
Isp (1 atm) 205 s
(vacuum) 230 s
Fuel consumption 100.49 Units of fuel/s

Thrust vectoring 2 °
Fuel 8000.0 Units of fuel
Burn time (1 atm) 71 s
(vacuum) 79.6 s

The S2-17 "Thoroughbred" Solid Fuel Booster (also known as an SRB) is a solid rocket booster used to provide a short burst of additional thrust to a rocket. It comes as a single unit. The engine and fuel tank are one single part which means that it isn't possible to increase the burn time for it by adding more fuel tanks.

It is one of the two 2.5m solid rocket boosters, smaller than the S2-33 "Clydesdale" Solid Fuel Booster.

Product description

When Jeb asked Kerbodyne how to lift his house into space, this is what they came up with. The Thoroughbred is a truly massive solid rocket fuel booster. It is also the first booster Kerbodyne has managed to add thrust vector control to, adding surprising agility to this powerful motor.



Like other SRBs, the Thoroughbred can be fired once, and cannot be shut down or throttled once active. While assembling a vessel, it is possible to adjust the amount of solid fuel and thrust using tweakables in the VAB or SPH. If planned properly, this can provide some control during flight. Unlike smaller SRBs, the Thoroughbred has thrust vector control, making it easier to control while active.

Once ignited, a Thoroughbred with full fuel and thrust will burn for 79.6 s. If jettisoned while empty, it can parachute to a safe landing with three Mk2-R Radial-Mount Parachutes.

The minimum thrust required for the Thoroughbred to lift its own weight off Kerbin's surface at sea level is about 45.5%, or about 686.7 kN.

The Thoroughbred can be radially mounted like other SRBs to increase thrust and TWR during liftoff. Due to its large size and thrust, it can also be used as a standalone first stage, mounted below the rocket. However, because of its low specific impulse (Isp) and high mass, it is not recommended to use it beyond the first stage.


  • Initial Release