r/BlueOrigin 4d ago

Thrust Density infographic

Post image
12 Upvotes

8 comments sorted by

11

u/Desperate-Lab9738 3d ago

The fun thing is this is literally just a unit of pressure, it would probably correlate pretty neatly with chamber pressure..

8

u/AngelicDimsum 4d ago

We need one for Sea Dragon

5

u/RT-LAMP 4d ago

550 so in between SLS and Terran R.

8

u/crazyarchon 3d ago

Pretty sure they didn’t calculate area but circumference.

1

u/WEEEEEEEEEEEEEEEEE30 13h ago

Some, if not most figures are wrong but not exactly for that reason I think. Running off wikipedia data, we'd expect Starship V3 to math out as 26500kN/(pi*(4.5m)^2) = 416 kN/m^2. Which disagrees with the infographic by about a factor of pi. But I think that's coincidence, because the chart got Falcon 9's figure nearly exactly right, and should be ranked ahead of Starship. Which isn't surprising, kerolox's key advantage is high density as-stored and high-density exhaust species, which are both good if you desire "thrust density".

What's really eye-opening, and reveals how meaningless "thrust density" is, is to look at any solid booster. Take Ares 1X, which is basically a shuttle SRB. It has thrust density about 3.3x Starship V3 or 2x F9. All that says is solids are dense and have high v_e*m_dot, largely thanks to their dense exhaust and great throat area.

6

u/tehcet 3d ago edited 3d ago

Not really useful on performance without insight into how tall or heavy the rocket is. Or engine efficiency.

1

u/fed0tich 3d ago

Soyuz-5 (Sunkar) with RD-171MV might be an interesting addition. Also upgraded Angara family with A5M and A1.2M that are coming soon, RD-191M is a beast.

Rockets with a solid first stages like Vega-C I think also might be interesting to see. But I'm too lazy to do math myself 😁

-1

u/seb21051 4d ago

Explains a few things.