Jarnis

You are misremembering. - Falcon 9 Flight 1 - First try was aborted seconds prior to liftoff (out of range engine parameter, turned out to be sensor failure). Second try worked out. - Falcon 9 Flight 2 (COTS Demo 1) - Abort with 2:48 on the clock (false telemetry data). Second attempt worked out. - Falcon 9 Flight 2 (COTS Demo 2) - Abort after engine start (higher than acceptable pressure in engine 5, faulty check valve). Valve replaced, success 3 days later - Falcon 9 Flight 3 (CRS1) - First try worked. Partial success (loss of one first stage engine 1min 19s into launch) Primary payload OK, secondary (Orbcomm test sat) not deployed to right orbit due to performance lost with the engine loss. Mostly because the initial orbit was so close to ISS orbit and upper stage didn't have quite enough fuel left for NASA-approved safe restart for Orbcomm delivery (NASA didn't want to take any chances) - Falcon 9 Flight 4 (CRS2) - Couldn't find exact details but I recall this one went up also on the first try, had issues with thrusters (pressurization problem, cycled/"hammered" some valves to clear it) - Falcon 9 Flight 5 (F9 v1.1, CASSIOPE) - had to repeat their hot fire test once to get everything sorted, actual launch was on the first try - much to the surprise of pretty much everyone. Usually the first launch of a new rocket never goes up on the first try. So... you most likely are just remembering the last ones (CRS1 and 2, CASSIOPE) which did launch on first try. Not true for every single one This one has been the most temperamental one, I grant you that. New pad structure and still-fairly-new rocket. Yep. Which is also probably one of the reasons they want to take a look - they worked fine in Hot Fire and now the signature (thrust build-up) was off. "Why?"

Nope. They already checked it after first days of aborts. Here is the whole timeline so far; - First try, extra hold time at t-13min because first stage liquid oxygen vent/pressure relief valve failed to close properly. They held for a bit, cycled back the clock and decided to try again. - Second try, this bit worked fine but second time around inside 13min final count a ground power supply had out-of-spec voltage and that tripped a hold. They looked at it, decided it was just too conservative limit and recycled to t-13min - Third try they got fairly far into the count (t-4min) but this time the liquid oxygen valve again suspect as there were off-nominal pressure readings from 1st stage tank. Additionally there were two glitches with the strongback. When it retracted for the last attempt (only one which got that far) the air conditioning ducts attached to the fairing (to keep satellite cooled) detached earlier than normal due to a tangled line. Not a showstopper. When the third abort was called, the strongback returned to upright position very slowly (some glitch with that). Between Tuesday and Thursday they took the rocket horizontal, inspected the LOX valve that had caused grief (and I assume, fixed whatever was wrong with the strongback) and were ready to try again. On Thursday the first attempt took them all the way to ignition of all 9 engines but the computer shut them down immediately as two of them were showing slower-than-expected thrust build-up. Falcon 9 is designed for this; Engines start, computer checks all values are fine and THEN releases the rocket from the pad. Computer said no. Blame the SpaceX MechJeb. They recycled for a second attempt while engine guys (probably back at the factory) went over all the data from the first attempt. They knew they would not launch if the engine guys were not happy with the data they had. Nothing prevents SpaceX from recycling without inspecting the engines outright - they are designed for re-starts - but it does require that the guys responsible for those engines fully understand what caused the first cutoff. They set the new time at the end of the launch window and everything went fine until ~T-48 secs (just after the point where internal computer takes over the control of the vehicle) but at that point the guys responsible for the engines basically said "nope, we are not comfortable enough with the data we have / the time we had to analyze it. Let's abort and take a close look at the engines to ensure there is nothing wrong". I don't blame them for electing to be conservative. Would YOU want to go over complex engine telemetry data while a countdown clock is ticking and a satellite insured for $200M is sitting on top of it. Your call may decide if that satellite is toast or not... The valve that caused them grief on Tuesday *was* inspected and cleared prior to Thursday attempt. There was no reason to inspect the engines prior to the Thursday 1st attempt - they had passed testing at McGregor and had already started up once during hotfire test at the pad. They were considered good. Didn't quite work up to specs set for the flight computer this time around and SpaceX wanted to be sure there is nothing off so we wait for another day...

Yep. UR-700 is definitely very Kerbal. One standardized core being used in large numbers.

Yep. Realistic modeling would require... - Making empty tanks a lot lighter. KSP stages have really poor mass fraction - Making engines heavier - Making fuel lines heavier and limiting the fuel flow per fuel line (or have multiple sizes of fuel lines with different specs)

Hey, SpaceX-ology is the natural reaction to the secretive (understandable for a private company) cutting-edge space-related developments going on there. Lots of inquisitive and smart space nerds want to know more! And unlike what US govt. had back during the cold war, we don't have CIA and spy sats to get us info. Have to resort to very dated sat shots of test stands off Google Earth and "spy photos" snapped by other nerds who happen to visit SpaceX facilities And speculation. Lots and lots of speculation. Mixed with over-analyzed statements by Elon Musk and carefully freeze-framed YouTube videos of launches and tests, plus some PR photos that SpaceX and/or Musk sometimes pass out. Image file metadata getting analyzed and videos getting digitally enhanced to fuel more speculation? You bet!

Read "Rockets and People" volume 4 (available as free ebook from NASA website) and you learn a LOT more about N1. http://www.nasa.gov/connect/ebooks/rockets_people_vol4_detail.html N1 was killed by a large number of errors... - It had completely unrealistic schedule. In USSR nothing was done without a decree and a schedule. If one was set, it was done - even when it was completely impossible. So a lot of effort was wasted on completely unrealistic deadlines. - It was being built without suitable test rigs. The only way to test the first stage was to launch the thing. The engines were not designed to be reused - they couldn't be "hot-fired" (or full-duration test fired) on a test stand and then flown - the first time the engines were used was the real flight. Oh, sure, they did test individual engines in test stands and hoped to know how the mass-produced engines behaved, but nothing beats actually test-firing every engine before flight (like SpaceX does it) or at least testing whole stages on test stand to see that they work as advertised. Soviets just took 30 mass produced engines, never fired them, built a whole stage complete with analog KORD control system to ensure that any failing engines would be shut down on the fly (it had multiple-engine-out capability), and hoped they all worked in a full-blown launch. The answer to their hopes was "nope". - "No suitable test rig" was due to Soviet development style of "we'll just build a bunch, keep launching them and fixing things as they crop up" used in ICBMs. Except that they couldn't exactly afford to build a dozen N1s just to get one to work. Incredibly they built almost a dozen and flew four of them, full stack, with every single one going all Kerbal before end of 1st stage flight. One of them happened to take out the launch facilities, causing substantial delays as it was rebuilt. Last try got pretty close - about 7 seconds short of staging. Each one failed due to a different issue but at least three of those could have been debugged out of the system in test stand firings. So much for the plan of testing in flight.. N1 1L and 2L were test models N1 3L - first launch attempt, engine fire, exploded at 12 km N1 4L - never launched, parts used for other launchers N1 5L - partially painted gray; early launch failure destroyed pad N1 6L - launched from the second pad 110, deficient roll control, destroyed at 1 km N1 7L - all white, last launch attempt; engine cutoff at 40 kilometres (22 nmi) Rockets 8-10 were scrapped when the program ended. Just as they were getting better engines (NK-33s, later used in Antares rocket) the program was shut down and efforts directed towards Energia-Buran - because Soviets had to have their own space shuttle and all that. Did an amazing job with that too, except that by the time it was ready, USSR was done for and the budget dried up.

I am in L2. I just can't link to those threads... and yes, it is still just something that exists "on paper". Still, I think they will eventually try it.

Lots of good discussion on Falcon Heavy http://forum.nasaspaceflight.com/index.php?topic=32528.15 Probably more than you can possibly have time to read

It doesn't cost more because it costs more to do this. It costs more because the payload is larger. In rockets you do not pay based on how much it costs do do something. You pay by the payload mass delivered to orbit. Crossfeed one delivers a lot more. Also the higher price for bigger payload on FH also covers the fact that bigger payload will go with expendable FH that will not return boosters. You pay for the fact that at least two out of three cores just turned into scrap rather than landed back.

* In real life, your crossfeed pumps do not weigh 0 grams. * In real life, your crossfeed fuel lines do not weigh 0 grams. * In real life, pumping around cryogenic propellants between rocket stages at rates eaten by the engines is Hard - you need big fat pipes, you need heavy plumbing and you need a lot of careful design to avoid that plumbing from failing in flight. You also need to close those pipes very quickly and securely without spewing stuff all over the place (any leaks potentially causing a Rapid and Unplanned Disassembly Event as the propellant cloud goes boom) when staging the side boosters. But SpaceX is actually going to try it (with two side cores) with Falcon Heavy. It has a crossfeed-enabled version planned that would use side core fuel to run all the engines (27 of them!) at liftoff and when the two side cores are nearly empty, they are ditched (and they will return to land for reuse! using the remaining fuel to slow down the fall back & steer for propulsive landing) while the central core continues on at almost full fuel load. Gives a substantial payload boost, but it remains to be seen how much they lose to the added weight of the crossfeed lines and pumps. It Should Work® - on paper - but it hasn't been tested yet. Russians also have plans for a design like this but they have never built one. I believe their version had four side cores.

Meh. So much for semi-realistic exploration of Kerbin system. Guess I have to stick Jeb in a can for 3000 days. Good thing Kerbals don't apparently eat anything.

Yes, but once you want to finish the mission, there is no way to "recover" without landing (ie, getting a "grand total for this mission" screen). Except, in theory, if I plot a trajectory for small cosmic accident for this probe. Going to test that next.

Ah, looks like the science in the science building goes up immediately on transmit. But I guess no way to get summary of the mission total then? Edit: I wonder if I'd get one if this probe gets to have an "accident" with one of the Joolian moons...

So I had this great plan of sending a very lightweight probe to cruise around the solar system and do science®. How do I "cash in" without landing back on Kerbin? If I terminate a flight, I get nothing.

We need surface sample collector for probes and robotic rovers. A tiny backhoe plus sample container. For my unmanned Duna sample return!