Cool SpaceX Projects That Almost Happened

[Zed_Noir]

- Falcon 9 Block II

Isn't this the Falcon 9 v1.1?

No. It was cancel in favor of the F9 V1.1. It was a more capable version of the Falcon V1.0 AKA Falcon 9 Block I with upgraded Merlin 1C engines.

[baldusi]

- Falcon 9 Block II

Isn't this the Falcon 9 v1.1?

The original Merlin 1C was an 85klbf engine (at sea level) for the Falcon 1. When they win the COTS contract they propose to increase the thrust to 125klbf and use 9 instead of the 5 they had proposed for the Falcon 5. This was supposed to be the definitive Falcon 9 (i.e. Block II). But they could only push the Merlin 1C to 95klbf at first. And that's the version of F9 that was retroactively renamed to v1.0. If you look at the 2009 Payload User's Guide, you'll not that they talk about Block I and Block II.
Incidentally, they had planed fro Block II to be reusable by means of parachute deployment. They discovered after the first launch of v1.0 that the cores were burning on atmosphere reentry, and thus they would need a retro burn. Then they arrived at the conclusion that the optimum was to do fully retropropulsive return. And they learned a lot about mass manufacturing. The aileron and tringer construction of the Falcon 1's tanks was fine for such a small rocket, but once implemented at the F9 scale it was very manual labor intensive. The Merlin 1C construction had similar issues. And a long list of etc.
So, while the original idea was to uprate the engines and may be extend the tanks a bit mutated to a completely new engine that shared nothing but inspiration with the first incarnation. I'm talking about the v1.1, of course.

[Elmar Moelzer]

They discovered after the first launch of v1.0 that the cores were burning on atmosphere reentry

I thought they were just torn apart during the uncontrolled and way to fast reentry. I never heard that they were actually burning. That would be rather odd given the speeds involved.

[baldusi]

They discovered after the first launch of v1.0 that the cores were burning on atmosphere reentry

I thought they were just torn apart during the uncontrolled and way to fast reentry. I never heard that they were actually burning. That would be rather odd given the speeds involved.

I might be misremembering. I think Elon stated about a "sort of bellyflop" and then the stage was destroyed.

[Dudely]

The original intention was to bellyflop the cores with the aid of parachutes. They tried, and it didn't work- it was destroyed. Then they took the parachutes off and waited for 1.1 for powered landing.

I have also heard that eventually going to powered landing was decided upon before the parachutes failed.

[sdsds]

Merlin 2 [...] got to a fairly high level of design before being cancelled in favour of Raptor

I'm on the edge about this one. Is there a public source of information on how close to "almost happening" this came?

Hydrogen fuel upper stage cancelled for methane fuel Raptor.

I never heard of a serious LH2 plan at SpaceX. Details?

[go4mars]

I never heard of a serious LH2 plan at SpaceX. Details?

There were diagrams and specifications, I believe in the "Markusic presentation".  IIRC, the engine nozzle > 11 meters diameter. 

Also, Merlin 2 was going to be >3.6 million pounds thrust per engine at one point.  Noteworthy IMO.

[baldusi]

The Markusic presentation had a render and a point diagram of each hydrolox Raptor (150klbf) and Merlin 2 (1.7Mlbf at Sea Level, 1.92Mlbf vac). Point diagram means that they had temperature and flow mass at every interesting point. IIRC hydrolox Raptor nozzle wasn't 11m. It had a big expansion ration, but only because it had SSME like Pc.

[sdsds]

OK, based on those summaries of the Markusic source I've added both hydrolox Raptor and Merlin 2 to the list. Thanks!

[anonymousgerbil]

How long before we can add Dragonlab to this list?