sevenperforce

Looks like you witnessed the re-entry of a CZ-2D rocket body, the upper stage of the Long March rocket used to launch the Apstar 6E comsat to GTO back in late January.

True, but I wonder if the engine that stopped on its own was on the opposite side, to balance thrust, as per flight software. At the same time, I wonder if it has enough gimbal authority to handle a single engine out. Nope, not needed to balance thrust. Even Falcon 9 has enough gimbal authority to handle a single-engine-out anywhere in the outer ring without needing to shut down the opposite engine. With 33 engines, an odd engine out is barely felt against the mighty gimbal authority of the central core of 13 engines all gimbaling at 15 degrees.

Doubtful; I think Elon would have characterized it differently if that were the case.

I did a TikTok using the first NSF footage: Link here in case it doesn't embed properly.

The people on NSF are discussing this. It may be that they only replace and refire those two engines, then proceed.

The billowing clouds were HUGE. Just absolutely huge. Way, way bigger than I could have anticipated. The absolute lack of anything on fire, smoking, or apparently damaged on GSE is impressive. That's exactly what they need to have.

KABLOOOOOOEY In the best of ways

Understanding that we are holding at T-0:40 and no siren is expected?

On Starship, the LOX tank is under the CH4 tank, but last I recalled the LOX tank is on top with Superheavy. Is that still the case? If so, I agree -- more CH4 than I was expecting. LOX is much heavier and so I was expecting more LOX and less CH4.

Any word on the current countdown time? I'm not listening to the patter audio.

On the other hand, you could also say that the Atlas rocket that launched Glenn was more efficient than the R7 that launched Sputnik. One of the efficiencies lies in the incredibly low dry mass of the balloon-tank Atlas core stage (a mere 2.35 tonnes) compared to the much beefier R-7 core (6.47 tonnes). Sputnik had a mass of 83.6 kg, while the Mercury capsule (including John) had a mass of 1,352 kg, so the total mass placed in orbit by the Atlas (at burnout) was 44% lower than the total mass placed in orbit by R7. It's not a direct comparison, anyway. Sputnik's core stage reached a 215x939 km orbit, which is substantially higher than the 150x248 km orbit reached by Glenn.

I went in and did the detailed math, correcting all of the data and going much more precise. Some corrections. Got about the results I expected: Unsurprisingly, N1 wins out by far, at nearly 2.5% of world power consumption during its first launch. Saturn V's first and sixth launch beat out Superheavy, but its last launch did not. The first launch of the Shuttle and the first launch of Energia both got over 1.2%. At the current annual increase of annual energy use, it's very unlikely that we will ever see N1's record beaten.

Always surprises me how aggressively they turn the fins. On the annoying stream, they were asking what the TNT equivalent would be if the Superheavy was fully filled with propellant. They said "we don't know, someone do the math" so of course I did, and it's 8.6 kilotonnes TNT equivalent, or approximately half the energy of the Fat Man nuclear fission bomb dropped on Hiroshima. Of course, that would assume complete mixing of the fuel and oxidizer with total detonation.

To their credit they are currently talking mostly about hardware.

I had an absolutely awful dream that they initiated the startup sequence and 20 of the engines blew up in sequence within a split second, like balloons popping. I even remember thinking "is this a dream" so I came to this thread and nope, it wasn't a dream -- all of y'all were on here lamenting it. @tater and @Beccab were generally dour, @CatastrophicFailure expressed hope that the GSE weren't too badly fragged, and @kerbiloid was, well, @kerbiloid.

I calculated Superheavy’s power consumption using its vacuum thrust and specific impulse (because that’s the actual energy consumption even if the thrust and Isp are effectively lower at sea level) in comparison to the world’s total power consumption as of 2019, 1.91e13 W. World energy consumption fell by 6% in 2020 but rose to 100.5% of 2019 levels by 2021, which is the last year for which we have complete data. Extrapolating from 2019 and skipping 2020 for obvious reasons, today’s power consumption is high enough that Superheavy will technically only be increasing the world’s energy consumption by 1.39%. Not a big difference. In 1980 (which is the first year that the EIA lists data from), world energy consumption was 49% of what it was in 2021. So if Saturn V had launched in 1980 (its last launch was actually 1973), its vacuum power consumption of 115.9 gigawatts would have been 1.2%. I haven’t dug up all the historical energy consumption statistics yet, but it’s probably safe to say that the Saturn five rocket consumed more than 1.39% of the world’s total power consumption when it first launched, but less when it last launched.

When Superheavy lights up all 33 engines tomorrow, it will briefly increase the world's power consumption by 1.4%. Let that sink in.

JELLY

Rarely happy about a scrub but I'm happy for you on this one.

No, it would be considerably more. Oberth is your friend. I haven't done the math, but it might actually be more efficient to burn from GSO to GTO and then burn from GTO to intercept. I just did the math, and while an Oberth gate maneuver (burning down into an eccentric orbit and then burning again at perigee to raise) isn't indicated, the burn you need is still pretty significant. In GEO, you're circling Earth at just under 3.1 km/s; you'll need to add another 1.05 km/s to raise your apogee to 384,000 km for a lunar intercept trajectory. Granted, that's less than the 1.5 km/s disposal burn you'd need to do to lower your perigee into Earth's atmosphere. But still much more than end-of-life comsats have in their tanks.

No, it would be considerably more. Oberth is your friend. I haven't done the math, but it might actually be more efficient to burn from GSO to GTO and then burn from GTO to intercept.

I've been waiting for this.

Uhm...in theory, yes. I suppose. What happened to "the more simple an idea"? See above. You said "the catch" but I think you meant "the appeal"? If thermodynamics is getting thrown out the window then I suppose all bets are off. Agreed.

The most promising scramjet designs use a standing oblique wave detonation strategy already, and while that's certainly very efficient, it would be a very different geometry than a rotating combustion rocket engine. Scramjet engines typically need a very large region for mixing the fuel with the incoming air before it enters the combustion zone (whether shock-induced or from a flameholder) which is another significant difference. However, it would be perfect as the core of an air-augmented rocket, and if the complex physics of a rotation combustion rocket engine could be mastered to the point that it could burn at a range of mixture ratios, then it could even function as a stationary ramjet. The challenge with airbreathers is generally that even under the most ideal of conditions, the theoretical maximum airspeed of a given design (a) is still only a fraction of orbital velocity and (b) takes place in a high-drag, low-acceleration regime. If you're going to space you need high acceleration, so your switchover engines need to be large enough to provide high acceleration in a high-drag environment, which means they need to be just as heavy as if you were using a pure rocket approach. And then you're almost immediately going to start thinking about an air-launched approach.

The typical laser pointed at the moon makes a spot much larger than the moon, so you may be off by several dozen orders of magnitude.