RCgothic

The engine sevenperforce suggested - LANTR - is a nuclear engine, not a chemical engine. The methalox engines/raptors were suggested as landing engines, not the main stage propulsion.

I think this nomenclature makes a lot more sense: RC, RB and (presumably) RV numbers. No more getting raptors confused with ships.

A good round up of the current status:

I think the pic they chose for the YouTube thumbnail was of the two parts being stacked. It looks like there is a gap because there literally is a gap. When it's properly mated there isn't. The ribbed portion is external reinforcement of the common dome area, as has been mentioned.

Assuming you want a circular orbit in LEO, orbital velocity is ~7800m/s. Ground speed is cos(latitude of launch site)*460m/s due east. If your intended orbit is at inclination theta, then your heading (from North) should be at angle phi. With two sides and the angle between them (the angle between red and orange is theta), the green DV can be found from the cosine rule: a^2 =b^2 + c^2 -2bc*cos(A). The missing angle can then be found from the sin rule, a/sin(A) = b/sin(B) = c/sin(C). Note that the calculated DV will not be inclusive of gravity and atmospheric losses, so a little extra will be required which is highly dependent on how efficiently a particular rocket is at getting to orbit.

Booster 3 is departing.

That's a great explanation! Section 7 is in stack up:

Also I think this is the best look we've ever had of the bridge crane. Doesn't seem to span to the wings of the bay. In line with the door only. Interesting.

Factoid:

Correct. In cases 1 and 4 the heading/azimuth is undefined. The rocket is not pointing in any compass direction.

When discussing orbits, pitch relative to virtual horizon is more generally useful. The KSP Navball also uses this convention.

Yes, with 3 the core stage might as well be stretched as well. But I believe 2 would work well enough, outside perhaps the very lightest and heaviest payloads.

Orbital inclination - the angle of the orbital plane to the plane of the equator. Pitch angle - the angle of the rocket with respect to the virtual horizon (to the rocket's current horizontal plane with respect to earth). Heading - the compass direction.

Pretty sure Raptor could do the job from a *performance* perspective. The *slightly*lower thrust can be compensated by SRBs on takeoff and the *much* higher ISP of the Raptor would then more than make up for it. <327s for BE-4 Vs 350s for Raptor at SL. But you can't just mix and match rocket engines, even with similar fuels and performance values. It'd take an extensive redesign.

Trans-shipping of Cargo is going to be important if they're going to reuse LSS for lunar downmass. Got to restock it somehow.

Personally I'd err towards Late August.

They weigh and cost a lot more, and the weight doesn't matter because generally the wings on a jet is holding them up and they're fully reusable. Using them in a rocket, ISP is optimal at SL and in a vacuum, so a small bit of ISP is gained just before the first stage separates. But late in the burn it's carrying way too much dry tank mass. The engines also have to shut or throttle down to stay within structural limits and become additional dead mass. Comparatively, the Two Stage design has slightly worse ISP just before separation. It is also carrying more more engine and staging mechanism mass, but only early in the flight where that matters less. Later where it matters most it has less tank mass, fewer engines, and the engines weigh comparatively less than a compensating design. Two stage still wins. You want a compensating engine when you are constantly moving between different altitudes, throttle settings, and not trying to minimise dry mass. A rocket has just two regimes, one of which it stays in very briefly (SL), and dry mass is very important. It's a better optimization to go with a staging event