BACC "Thumper" Solid Fuel Booster

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BACC "Thumper" Solid Fuel Booster
Part image
Solid rocket booster by
Rockomax Conglomerate

Radial size Small, Radial mounted
Cost (total) 850.00 Funds
(dry) 358.00 Funds
Mass (total) 7.65 t
(dry) 1.50 t
Drag 0.2-0.3
Max. Temp. 2200 K
Volume  ?
Impact Tolerance 7 m/s
Research General rocketry.png General Rocketry
Unlock cost 2 800 Funds
Since version 0.16
Part configuration solidBoosterBACC.cfg
Solid rocket booster
Maximum thrust (1 atm) 250.00 kN
(vacuum) 300.00 kN
Isp (1 atm) 175 s
(vacuum) 210 s
Fuel consumption 19.42 Units of fuel/s

Thrust vectoring No
Fuel 820.0 Units of fuel
Burn time (1 atm) 35.2 s
(vacuum) 42.2 s
Testing Environments
On the surface No
In the ocean No
On the launchpad Yes
In the atmosphere Yes
Sub orbital Yes
In an orbit Yes
On an escape No
Docked No
Test by staging Yes
Manually testable Yes

The Rockomax BACC Solid Fuel Booster is a large solid rocket booster.


BACCs are one-shot rocket boosters often used to help get the massive bulk of a large multi-stage rocket off the ground. They burn at a constant thrust until they run out of fuel and then cease to work. It should be noted that more boosters doesn't reduce the need for liquid fuel, as one must also take into account thrust-to-weight ratios. Thrust can be regulated with tweakables. The minimum thrust required for booster to lift its own weight off Kerbin's surface is 24 %, or about 76 kN.

BACC Solid Fuel Boosters are prone to overheating, especially when large numbers are clustered together. The best way to prevent this is by using custom staging to stagger the firing and attaching additional parts that are not SRBs, typically parts such as struts, control surfaces or winglets, to act as heat sinks.

In version 0.25, the BACC has an on-pad specific impulse (or Isp) of 230, slightly better than that of the RT-10 Solid Fuel Booster and comparable to the least efficient liquid fuel engines. Its thrust-to-mass ratio is high enough to make it a popular choice on first stages.

Product description

Filled with a new, even more volatile fuel, the BACC offers semi-reliable performance at a good price.


  • Thrust increased from 300 to 315. Dry mass reduced from 1.75 to 1.5.
  • Thrust decreased from 550 to 300.
  • Other small performance tweaks.
  • Thrust increased from 400 to 550.
  • Initial Release