sevenperforce

I wasn't using a cargo bay -- those were all fuel tanks. I had figured that Mk2 rocket-propellant fuselages would save me on wing mass since they have appreciable body lift of their own. But, after iteration, I can see that they were really draggy. Structural overhead is what I was worried about. If a Spark can do a vertical-takeoff SSTO with an 5% payload fraction, but you need at least 10% of the vehicle dry mass to have a winged EDL onto landing gear, then adding more engines and more fuel is a losing game. But obviously you've demonstrated that it can be done! I still want to try to make one with Junos, just for the heck of it, but thanks!

And keep those butterflies from flapping their wings. The current webcast is derived from the "hosted webcast" of days gone by. They used to have a technical webcast, without commentary and with all values in m/s, and a hosted webcast with commentary and with all values in km/h. Now they only do the latter. Most of the world uses km/h. The US is rather an exception.

I've done little single-Spark vertical-takeoff SSTOs before, but not with the dry mass to pick up 4 Kerbals, get back down, and land deadstick on the runway.

I'll give it a shot. The TWR with Sparks alone is rather low, too low to maintain positive climb and positive acceleration simultaneously.

Trying to build a HTHL SSTO powered only by Sparks and Junos as part of my campaign to win this challenge: I assembled a semi-Grand Tour ship in LKO and it's already on its way around the Kerbol system, but I wanted to build an SSTO spaceplane to pick them up my four explorers when they return, since they have no heat shields and only a single drogue. My payload, then, is merely a probe core, a battery, and four empty command seats. If I can get into LKO, they can take care of the rendezvous and then the return should be easy enough. I've gone through about four different design iterations so far, all to no avail. The best I've gotten is the following: In case you can't tell, the eight Junos are attached to the rear node of the Sparks and then translated forward, to reduce drag. Yes, it looks like a Skylon. No, that was not intentional; this shape was the result of a LOT of iteration. I've tried a lot of different ascent profiles but I'm consistently burning out at around 40 km and roughly 500 m/s short of orbit. That's if I use the Junos for takeoff and then stage in the Sparks almost immediately, pitch up rapidly, and slowly lower the nose to keep my acceleration positive. Some of my early iterations had a Terrier on the back end or other adjustments, but this particular iteration has been the closest so far. Any tips?

A klew as to the differences between the three different landing burn types... Due to the ignition system plumbing used by SpaceX, only three of the nine Merlin 1D engines on the first stage are restartable in flight, and the core engine must be lit before the other two restartable engines. Thus, all inflight restarts begin by the ignition of the core engine, followed optionally by the ignition of the other two engines. In a "1-0" burn, the core engine is lit, burns for a while, and then is shut off. This produces the lowest thrust and is most often used in RTLS landing burns where the rocket has plenty of propellant margin for landing. It is least efficient, because the extra time spent firing causes gravity drag losses, but it produces the lowest stresses on the rocket and is the most reliable. In a "1-3-1-0" burn, the core engine is lit, followed immediately by the two adjacent engines. After some time, the two adjacent engines are shut down while the core engine continues to fire. Subsequently, the core engine is shut down. This is more efficient, because a lot of velocity can be canceled quickly by the high thrust of all three engines, while the single-engine termination gives finer control over the gentle touchdown. In a "1-3-0" burn, the core engine is lit, followed by the two adjacent engines, and then all three are shut off simultaneously. This is significantly more efficient than the 1-3-1-0 burn, but extremely difficult to control, because it is hard to predict transient thrust curves for three engines at the same time, so it's hard to be certain of exactly when you'll hit zero velocity and zero altitude. 1-3-1-0 burns have been used for almost all the more recent lower-margin ASDS landings.

No. They are testing a new method of landing first stages: specifically, a 1-3-0 landing burn, rather than the 1-0 and 1-3-1-0 landing burns they've done before. But there is no plan to land stages in the oceans and then recover them; this probably could not be easily replicated. In fact, it may have been that this particular burn had engine shutdown a bit late (or residual velocity at engine shutdown), causing the stage to dip a meter or two underwater while the engines were still firing and thus cushion the tipover.

SpaceX has done soft landings before, and every other time the booster tipped over and broke up upon impact. No one expected the booster to survive the tipover.

There's usually a temporary LOS on F1 at some point between the end of the entry burn and the start of the landing burn. Nominal.

Good lord that looks like a painting.

I believe you did. On another note -- where did they get that photo? Did Mr. Steven take that photo? What about the fairingsssss?

HOLY SH*T Wow. Just wow. That is...crazy. WHAAAAAA?!

Any news on the fairings? Anything?

Fun watching the slight inclination change on the tracking view.

Approaching second stage restart. Commentary back. Ears peeled for mention of the fairings.

Because it's the government.

No, but the explosion will.

I doubt water can actually make it into the tanks through the engines. They do a controlled shutdown so the valves will be closed. But that's a moot point, because without a solid surface to keep it upright, the stage will tip, hit the water hard, and break up. With explosions.

SECO.

"Stage 1 splashdown." I WANTED THE VIDEO

"Stage 1 is transonic." LOS callout for stage 1.

"Stage 1 entry burn has shutdown."

"Stage 1 entry burn has started."

"We are not recovering the first stage, but we are preparing for fairing sep..." I saw nitrogen plumes from the receding fairing.

MECO, separation, and a good ignition!