More than 251 tons and 14m payload diameter? I buy it.
Can you also include assembly sequence and realistic engine start/stop effects?

Problem with 2 RD 170 is they make the base of the booster 8 meters wide and reduce the amount of space available on the first stage for more boosters. 1 RD 171 don`t have enough thrust since I want the booster to have thrust and diameter comparable to shuttle srb and 7 RD 191 does it perfectly.
Of course, you could also use a tested, but never flown engine, but I assume hypergolic propellants are not your matter of taste today (RD-263).![]()
2 RD-170 could do more. Also the diameter of the stage does not need to change, if you use an Atlas like engine set-up. Would maybe look a bit more unusual, but is based on available engines, while a seven engine cluster would be more than just unusual.
And the Space shuttle boosters and the Energia boosters are actually not classic booster stages, but first stages.


Is the RD-171 bigger in diameter than an F1 or the never-built F1A?

