Space X

What I find great about this is that it's not mainstream news and that the successful landing on the barge is a footnote in the Space X release.
While Space will never be easy, some aspects are becoming more routine.

https://twitter.com/elonmusk/status/847594208219336705

Plans for a re-launch within 24 hours! We could be seeing launches several times a week in the next few years!

Just a clarification about tank pressurization. There is stored gas type pressurization that is comonly done with highly compressed He in storage tanks on the vehicle. Falcon 9 uses COPV bottles (Compressive Overwrap Pressure Vessel) immersed in the LOX tank to get more He in the same volume. Saturn 5 and Ariane use Ti bottles outside the tanks in the interstage area.
The other is autogenous pressurization where the propellant is used to pressurize the main tank by heating it up in a heat exchanger on the engines producing a hot gas that then gets fed back into the main tank. For both, methane and LOX, there would have to be separate heat exchangers as you do not want to mix hot CH4 with LOX and hot O2 with liquid CH4 (that's better left to the comustion chamber in the engines). This pressure is only high enough to keep the tanks from collapsing and providing enough head pressure for the turbopumps (very important to avoid cavitation). For Falcon 9 that pressure is about 3 bar. The actual pressure for the combustion chamber is provided by the turbopumps, they can go to insane pressures. The Merlin 1D is quite benign at around 97.2 bar, the Space Shuttle Main Engines were a bit toastier at 204 bar. The Raptor is a different beast altogether with the turbos pumping up to a whopping 303.36 bar.

What Captn' Midnight is refering to is pressure fed engine design in rockets. This design is very simple as it avoids all the turbo machinery that makes liquid rocket engines so complex and expensive. The fuel and oxidizer tanks in this design are basically high pressure bottles and the fuel and oxidizer gets fed into the combustion chamber by this pressure alone. It's simple but works only for small rockets and is quite inefficient (high weight for tanks, not that much pressure at all, poor ISP due to ever decreasing chamber pressure).

SpaceX launch in 2 minutes:

Id say thats one of its main selling points.

Imagine when a heavy is launched, we'll be seeing 2 boosters come back and land at Cape Canaveral and the heavy landing on the barge at sea, should be entertaining!

Stan27 wrote: »

It will be awesome, any idea when a date will be given for its launch ?

Sept / Oct is the expectation.

The next Spacex resupply mission to the ISS is next Thursday 1st June. Launch at 21.55 Irish time means it may be visible from Ireland about 20 mins after launch as it chases down the ISS in its 51.6 degree orbit.

Anyone know if it will actually be visible?

stupid question but which direction do I look and does anyone know how high from the horizon?

Launch scrubbed due to weather. Next opportunity Saturday at 22.07 Irish time.

josip wrote: »

They postponed because of the overcast sky over Ireland?

Yeah, sound lads at Spacex.

Didn't see it. Clear sky but think it was still a bit too bright to pick it out.

I've never thought of spotting it in the sky over here. I give it a try next time.

Beeker wrote: »

It depends on the payload. No launch is visible from Ireland because as you point out the curvature of the earth blocks any view towards Florida, either way the launch itself is well over long before it reaches Ireland. What we see is the payload after separation from the rocket in orbit passing overhead. A lot of the launches from Florida with satellites do head southeast towards the equator so will pass over Africa but payloads for the ISS launch northeast placing the satellite into an orbit that passes over Ireland.

did we not see the external fuel tank and shuttle over ireland a few years back.

Falcon9 going again in 8 minutes with a comm satellite!

Stage 1 has landed on the droneship already. Some achievement. Again. :eek: