Discussion Falcon Heavy might match first version of SLS.

[Unstung]

(And one Ariane 4 launch failed catastrophically because of sabotage, since then the security on CSG is really tight around launch)

This is interesting, but I couldn't find any evidence that one of Ariane 4's three failures was due to sabotage. Actually, I found contrary statements; citations provided.

 

[Urwumpe]

This is interesting, but I couldn't find any evidence that one of Ariane 4's three failures was due to sabotage. Actually, I found contrary statements; citations provided.

http://www.bernd-leitenberger.de/ariane4.shtml

An oil cloth, knotted twice, had been found in a 4 cm propellant line, where no oil cloths would have been permitted at all in the production (because N2O4 reacts extremely hostile with oil residues). The actual origin of the oil cloth was never determined, no company in the production chain used them, but security was increased in response and all such lines examined by endoscope during integration.

It also never happened again.

There is also a much more extreme version of the sabotage hypothesis around, which the newspaper "L'Express" published much later:

http://www.capcomespace.net/dossiers/espace_europeen/ariane/annexes/annexe8_echecs_ariane.htm

 

[Hlynkacg]

Citation needed.

What sort of citation would you actually accept?

Atlas dates back to the days where 10 - 20% percent failure rate was perfectly acceptable because you literally had hundreds more where that one came from.

Likewise, it's a matter of public record that Ariane 5 didn't fail once it failed 3 times (twice catastrophically) in a flight test program that was already over a year behind schedule. The first "operational" Ariane 5 launch was supposed to occur in 1995, but didn't get off the ground till December 1999. Further more the Mid-life extension upgrade (Vinci upper stage) was supposed to have it's first flight in 2006 yet is still languishing in development limbo 9 years later.

Finally, if "Maturity" is in fact a matter of not making the same errors twice or understanding what you are doing, I would contend that SpaceX has a far stronger claim to that label than Roscosmos or NASA's in-house engineers do at this point.

 

[Urwumpe]

Likewise, it's a matter of public record that Ariane 5 didn't fail once it failed 3 times (twice catastrophically) in a flight test program that was already over a year behind schedule. The first "operational" Ariane 5 launch was supposed to occur in 1995, but didn't get off the ground till December 1999. Further more the Mid-life extension upgrade (Vinci upper stage) was supposed to have it's first flight in 2006 yet is still languishing in development limbo 9 years later.

The Atlas failed mostly in the 1960's, so that is hardly a reference.

And the Ariane 5 has either two (catastrophic) or four (including partial failure, in which the wrong orbit was reached) failures. Not three. But still: it actually never failed outside the two test flights required by Arianespace.

Also, the four years development delay had political reasons, not technical, as you might find out by a quick research - just read up on the ESA program changes from 1987 to 1994. Hermes was cancelled in that time and the Ariane 5 was initially designed for launching it as primary payload. And afterwards, the CTV was cancelled and the ATV remained - but that had only little impact on the first Ariane 5 launches (But on the ECA launches).

Only the ECA development had real technical delays in its development, and after is qualification flight failure and the failure of Columbia, another set of major program changes was decided on the 30th May 2003 - which shoved the next ECA launch to 2005. The third ECA launch was already the first of the PA orders - which reduced the launch costs by about 30% simply by more economic production organisation.

 

[Admiral_Ritt]

So, are we supped to ignore that the Falcon heavy will be
lighting up 27 engines. There must be a lot of confidence that
no single engine component will fail in a way that will result Total loss of the Vehicle. Is that system going to give 95% reliability?

While the Delta IV heavy is not in a class with the F-heavy,
it is instructive that they have only 3 engines light up on take off. Don't
get me wrong, if ONE of those engines fail even non catastrophically it would
be in trouble.

But maybe it's better to lean towards the delta example however and
have only 2 engines (with gimballing nozzles) for each booster and core. (I know it will lower performance and SpaceX would have to develop a much larger engine.

But 27 engines really cool me on the F-heavy.

 

[Urwumpe]

But 27 engines really cool me on the F-heavy.

Well, the 30 engines of the N-1 had been not so much a problem of the engine reliability, but about the complex interactions that are possible with so many engines. The more engines you have, the more complicated interactions are possible... in aerodynamics, hydraulics, pneumatics, and electrics.

But the N-1 is hardly a good reference there. The control system of the N-1 had been for example excessively complicated and failure prone. Instead of gimballing all or some of the engines, the N-1 had the engines mounted slightly off axis and controlled the rocket by throttling them in groups. Now, if you remember how complicated it is to throttle one engine, imagine you have to throttle many engines in a complex choreography every second. One engine failure meant that also at least one equivalent engine in the opposing group had to be shut down. Which again inflated the failure risks a lot.

 

[ISProgram]

here must be a lot of confidence that
no single engine component will fail in a way that will result Total loss of the Vehicle. Is that system going to give 95% reliability?

It is worth noting that each successful Falcon 9 launch flies with 10 Merlin onboard. By now the engine has "flown" well over 150 times. That's more than practically any other domestic US rocket engine. More than the RD-180. It's also using a relatively safe and reliable engine cycle.

F9 and FH also have engine-out capability, so a few engines (on the first stage(s)) losing their cool won't condemn the mission to failure.

Only time will tell if it gives 95% reliability.

While the Delta IV heavy is not in a class with the F-heavy,
it is instructive that they have only 3 engines light up on take off. Don't
get me wrong, if ONE of those engines fail even non catastrophically it would
be in trouble.

Delta IV gets partial thrust in just one engine, it's going to be in more than just trouble. This can be said for most LVs, an engine out would probably end in a LOV situation.

But 27 engines really cool me on the F-heavy.

IMHO, the technical feasibility of FH's propellant crossfeed is what should cool you. It's a lot more complicated than it looks at first glance, SpaceX is discovering this personally I think.

 

[Andy44]

The debate between fewer big engines vs. many smaller ones is an age old argument.

N1 vs. Saturn V was a major spectacle in this regard, but it's skewed by N1's awful track record and the fact that Falcon 9's uses a totally control different system.

 

[C3PO]

N1 vs. Saturn V was a major spectacle in this regard, but it's skewed by N1's awful track record ...

Those two didn't launch often enough to make any sensible statistic evaluation, not even close.