sh1pman

Good start. When’s the next B5 flight?

Absolutely gorgeous. Watched the launch with my whole family on a big screen, while explaining what’s so special about this rocket. Was asked “why hasn’t anyone else returned rockets from space before? It doesn’t look that hard!”. Didn’t really know what to say...

That looks to me like a 1-2 second shorter RTLS burn, at most. It may actually be longer, because staging will happen further downrange, and possibly at higher speed. Remember, you still need to burn off 2+ km/s of prograde velocity first.

30-40 km downrange and what, 100 or so km apoapsis after boostback? That feels pretty vertical to me. Stolen from reddit: Edit: the graphic shows that it goes even higher than 100 km, maybe 130 or so. It reminds me of aerobraking at Duna. If your lander is going straight down (like F9 RTLS), you won't aerobrake at all, even using a spaceplane with great gliding ratio. But if you set the periapsis to something like 20 km, eventually you'll bleed off most of your orbital velocity, and lifting body will be very useful for maneuvering and keeping the lander from falling down. So, IMO, titanium grid fins will be useful for slowing down during high-energy ASDS landings, where the core spends more time in the lower atmosphere, but they won't be much better than aluminium fins during RTLS (which is required for 24-hour turnaround).

It's just a scheme. Still, the first stage doesn't spend that much time in the dense atmosphere to cover any significant distance with gliding alone. It helps to steer it the right way and achieve terminal velocity faster, though.

Can you really boostback halfway? During RTLS the stage comes down almost vertically, overshooting at first, ad pitching to negative angles to hit the pad. If you do a shorter boostback burn, you'll just end up coming down vertically, but several kilometers away from the pad. Won't have much time to cover any significant distance with gliding. Let's say you're saving 30 m/s from the landing burn. If your stage is 1% heavier, it'll have 22 m/s less dv after staging. So it kinda cancels out.

During S1 reentry most of the fuel is spent for boost-back (for RTLS) and braking (ASDS) burns, which are done in higher atmosphere, where the aerodynamic drag is negligible, so these burns won't benefit from better grid fins. They may decrease the landing burn, but it's already much shorter than previous burns. So the fins might shorten the suicide burn from 5s to 4s (three-engine burn), which won't really save you that much fuel.

Yeah, it's very hard to even make a dent in liftoff TWR, but I was replying to this point: My point is that extra dv from uprated engines may be partially or even completely negated by increased dry mass of both stages, especially if they're going for S1 reuse.

If you double the dry mass, stage delta-v drops from 3.9 km/s to 3.5 km/s if the first stage is expended, or from 2.9 km/s to 1.9 km/s with RTLS (I've spent all this time doing the calculations!). That's a lot. S1 dry mass is critical to their ability to recover and reuse boosters.

They are bigger and denser than the aluminum ones, so they must be quite a bit heavier. After all, they are the biggest pieces of cast titanium in existense.

I think the dry mass got higher as well, due to all of these added things like reinforced octaweb, new legs, titanium fins, TPS on both first AND second stages, and other improvements meant to human-rate the rocket (making everything 40% sturdier than needed).

SpaceX airlines: “To the passengers of BFR flight New-York - Shanghai, the flight has been scrubbed till tomorrow due to some ground computers acting strangely. Have a nice day!”

Officially scrubbed for today.

I dunno, he said they're still reviewing the data...

MVac pre-cooling

One of the improvements to onboard AI brought surprising results...

Ever thought of doing these missions in RSS/RO? They'll be ten times more exciting!

Are they planning to modify the TEL for manned Dragon 2 launches?

Apparently, S2 is also block 5. Does anyone know how it's different from previous S2? Giant party balloon?

Surprise morning launch!

Booster, maybe not so hard. But BFS - it’s a huge friggin’ second stage - spaceship, jack of all trades, master of all. Sure, most of these things like carbon tanks, lifting body reentry, vertical landing, refueling, etc. were done before, but combining it all into one vehicle is a daunting task. I’m honestly amazed that they’re planning to fly it next year.

So, let’s see... 8 sets of old boosters remaining, first launch likely in 2020, and one launch per year. That means they have 10 years to come up with new boosters, which is plenty of time. I’m sure they'll manage.

I got mine from the Constellation pack. Will try the new one. --- Ok, installing the new version fixed all the issues. Thanks again!