sevenperforce

The titanium ones are reusable; the aluminum ones are not. Might as well burn up the aluminum ones they still have in stock; not like they're going to use them for anything else.

Damn, that's a beautiful sight.

No need to clean it off. We're talking about maybe 2-3 kg of soot on the whole first stage. If this was the upper stage, it would mean a 2-3 kilogram reduction in payload, which wouldn't be a problem for Falcon 9. But on the lower stage, we're talking about maybe a dozen grams of payload reduction, thanks to the rocket equation.

That is a rule, generally, but in this case the thread is more about "I think this can be done, but I'm not sure; let's work together and find out."

Yep, it's called the Aldebaran. http://www.projectrho.com/public_html/rocket/surfaceorbit.php Wet mass 50,000 tonnes. Single nuclear-thermal engine.

Rover wheels are a form of propulsion -- otherwise you could build a ramp and launch yourself off at speed with clever use of staging.

Messed around with the thrust limiter and got up above 48 km:

Here's my entry. I use a decoupler to get the Kerbal out of the pod and into the command seat, but its force percent is set to 0 so it provides no impulse. Hopefully that's okay. She's climbing in. Decoupling doesn't move the plane. Ignition! Building speed. Liftoff! No yaw authority at all. Fighting the canards a bit. Setting pitch to maintain a nice even climb. This looks to be about max range. Splashdown at a ground distance of 29,654 meters, but I'm sure I can do a good bit better if I actually pay attention.

The BelugaXL's cargo bay will only be about 40-45 meters long.

A Falcon 9 first stage wouldn't even fit under an airplane, let alone inside one. It's huge.

Well, no legs.

Upon review, you're probably using 85 tonnes as the dry mass of the BFR. But that's the dry mass of the spaceship. If we're talking expendable, then you should really be looking at the dry mass of the cargo BFR, which will likely be closer to 40 tonnes. 240 tonnes dry seems WAY too high. The ITS dry mass was quoted at 275 tonnes and it's twice as big. Setting the booster dry mass at 140 tonnes, the cargo BFR dry mass at 40 tonnes, and the fuel capacity of the booster at 3,075 tonnes, I get 225 tonnes to LEO without strap-on boosters. Adding 4 strap-on Falcon 9s increases payload to 309 tonnes.

What were you using for the BFR booster's dry and wet mass?

Of course then you'd need to plumb all nine engines for TEA-TEB but that's not too hard to do. Alternately, the Merlin 1D can throttle all the way to minimum and it gets the job done just as well. The actual real-world problem with a five-core Falcon Super Heavy is the same problem with the real-world Falcon Heavy: stresses on the core. The core has to lift the payload AND transmit the impulse from the boosters, and so you'd have to rebuild the core a second time to make it sturdier. Not to mention that you'd either have ridiculously massive payloads and EXTREMELY low TWR on the upper stage, or you'd have an orbital core every time, which makes it just slightly difficult to recover. From a Tsiolkovsky perspective, strap-on Falcon 9s are fantastic. Their lower isp drains fuel quickly and kills gravity drag. Trouble is, the BFR needs to RTLS, which means every m/s of dV carried beyond its design separation velocity is reduced by more than half, since it has to cancel downrange velocity AND boostback. Of course, if you want to fly a BFR core expendable, then slapping on Falcon 9s is perfect. But the cores will never be intentionally expended. By way of example: The booster typically stages at 2.4 km/s, reserving enough fuel to cancel that 2.4 km/s, boost back, and land. Let us suppose that adding a pair of Falcon 9 boosters gives 2 km/s more to the booster. Unfortunately, that doesn't mean separation happens at 4.4 km/s. The booster can only afford to add about 1 km/s to staging velocity, because it now has to slow down from 3.4 km/s instead of from 2.4 km/s.

You hafta take off horizontally to have a chance. Parachuting? Just jettison. This is not about recoverability.

The core took major redesign; the upper stage is still identical. A 4-booster Falcon Heavy would very nearly have an orbital core.

....but why not demonstrate the capability to RTLS? 90% sure there is. The US will probably have enough spare prop to brake by at least 2 or 3 km/s before entry. And the engine bell may act as a shuttlecock.

That's because the picture was taken on the way up. The "pinstripes" on the lower half of the reused first stage are weld inspections. You have to scrub off the soot before you can do an electromagnetic inspection of the underlying Al-Li weld. But they only scrubbed off what they needed to. Estimates say about 2.5 kg of total soot on the first stage, which is only a ~250 gram reduction in payload to LEO, so the mass isn't an issue. Are we sure the FH core is coming down on OCISLY? The Roadster is pretty low-mass; even for a trans-martian injection burn, the center core may have enough dV to boostback. I wonder what the odds are that the upper stage jettisons the Roadster, does a nitrogen-thruster flip, and burns backward to come back for an entry attempt. Just enough of a burn to bring it into an aerobraking trajectory, with PICA-X panels covering the PAF and fairing-style steerable chutes tucked around the Merlin Vac.

This is very simple. Place at least one Kerbal in orbit, using ONLY the LV-N engine for propulsion/impulse. Lowest launch mass wins. Go.

What about when it lights its engines on the pad, fires for a minute, and then shuts down because it's the static fire?

I believe we can be relatively certain it is not a mockup.

Yes, that's Falcon Heavy on the bottom left/center, with the second stage ready to be mated to the core. Nose cones on the side boosters are clearly visible. Unfortunately we can't make out much in the way of detail on the special core interstage. They have asked other sites to take down this image, as it evidently was not intended to be released.

If your plan is to orbit Mars before landing, then you have to do a braking burn. The lowest-energy Hohmann transfer has both the smallest exit burn at Earth and the smallest injection burn at Mars. If you want to do a faster transit, you need to add fuel for both a larger exit burn AND a larger injection burn. And since the extra fuel for the injection burn is extra payload for the exit burn, the exit burn must be correspondingly larger. Classic tyranny of the rocket equation. And since all launches to Mars thus far have been single-lifter affairs, the exponential nature of the rocket equation means you'd need to double or triple the size of your launch vehicle to even moderately shorten the transfer time. The BFR, of course, finds a way around this. If you're aerobraking in to Mars from Earth with a lifting body like the BFR, you get to skip the braking burn. This means any extra fuel you have can go straight to shortening the transfer window, without needing to hold any in reserve for a braking burn. And since it refuels from Earth, it's easy to add more fuel for a faster transfer. You can even do fun things like a high-elliptic transfer, where you place your transfer vehicle on an elliptic Earth orbit first, then refuel, then do the exit burn since you're already basically halfway there.

Launch as well.

Dick move, Elon.