SFS News: SpaceX - Falcon 9 Progress Update

Anyway, an increase from 125K to 140K is still quite impressive!

Yeah... I've read an article about the guy behind Merlin (and I think Draco and Kestrel as well) design. Forgot the name unfortunately, but he impressed me a lot.

Tom Mueller?

That's was interesting - 117k lbs to LEO is quite a big chunk of mass. Launch end of next year - so a while to wait!

Although Elon Musk really does need to practice his public speaking a bit more!!!

Could it be that they were running the 1A way below the original design specs, and that much of this upgrading is really just expanding the envelope, as they gain more test data and confidence in their design and manufacturing processes?

Specifying power levels over 100% may seem nonsensical, but there is a logic behind it. The 100% level does not mean the maximum physical power level attainable. Rather it is a specification, decided on early during SSME development, for the expected rated power level. Later studies indicated the engine could operate safely at levels above 100%, which is now the norm.

Could be. Or they just learn that they can actually safely go above original specs. Just like SSME that routinely run at 104.5% of original specs

Well, maybe they didn't believe Elon . I'm not sure where he got the 95klbs thrust figure. According to this the Falcon 1A had 75klbs and 1B 85klbs. Marcus says 125klbs for the 1C, and 1D will then be 140klbs. Maybe he just misspoke, and meant 75klbs?

As configured for use on Falcon 1 vehicles, the Merlin 1C had a sea level thrust of 350 kN (78,000 lbf), a vacuum thrust of 400 kN (90,000 lbf) and a vacuum specific impulse of 304 seconds. In this configuration the engine consumed 140 kg (300 lb) of propellant per second. Tests have been conducted with a single Merlin 1C engine successfully running a total of 27 minutes (counting together the duration of the various tests), which equals ten complete Falcon 1 flights.[15]

As configured for use on the newer Falcon 1e and Falcon 9 vehicles, the Merlin 1C has a sea level thrust of 560 kN (125,000 lbf), and an isp of 300.[16]