I was thinking a F9R could use it's ability to land to abort a failed launch. E.g if an F9R suffers an early stage engine loss, or later double engine loss.What would be needed to be done to allow it to land with a 2nd stage plus payload on top?My first thought was it needs to vent a huge amount of propellant to avoid overloading the legs during landing.
As previous posters have concluded: Asking a reusable multi-stage LV to perform an intact abort is to ask it to do something which is several times harder than a normal launch - after a failure has already made it impossible for it to do that... Saving the payload is already done for crew and might be doable for more fragile satellites, but saving the entire LV is probably only possible/worth it for SSTO (especially space planes).
...Overall, it's far from impossible but would be a complex process to develop and prove. It certainly isn't a capability that I'd want available from the outset as it would lead to delays and unnecessary expenses.
...I think planning for some of these scenarios is going to happen sooner than some might think. Basically, as soon as it becomes clear that the F9 first stage is recoverable. If there was a launch where four engines failed, SpaceX is going to want to try and recover the first stage (assuming the centre engine isn't one of them!). You'd simply keep the engines firing to burn off the propellant; launch the second stage and then try to land!
The correct way to go in the event of first stage engine failure is to abort the first stage recovery sequence to recover the margin needed to allow the second stage and payload to achieve orbit.
perhaps this should be moved to advanced concepts?because we are talking about 10+ years here, for sure.
Quote from: CuddlyRocket on 11/03/2013 06:59 am...I think planning for some of these scenarios is going to happen sooner than some might think. Basically, as soon as it becomes clear that the F9 first stage is recoverable. If there was a launch where four engines failed, SpaceX is going to want to try and recover the first stage (assuming the centre engine isn't one of them!). You'd simply keep the engines firing to burn off the propellant; launch the second stage and then try to land!I don't think planning for the kind of failure you cite is worth it. Losing four engines is very unlikely. Instead the effort should go into improving the reliability of the vehicle so aborts become less likely in the first place.
Quote from: Silmfeanor on 11/03/2013 05:14 pmperhaps this should be moved to advanced concepts?because we are talking about 10+ years here, for sure.No we're not. Once first stage reusability is demonstrated (which I think will be in the near future), it becomes obvious to ask whether there would be circumstances in which a launcher failure involved LoM but where the first stage is recoverable. If the answer is yes, it's sensible to plan for such situations - the first stage is a piece of equipment costing millions of dollars, even in the rocket industry you don't throw such things away unnecessarily.Quote from: douglas100 on 11/03/2013 04:27 pmQuote from: CuddlyRocket on 11/03/2013 06:59 am...I think planning for some of these scenarios is going to happen sooner than some might think. Basically, as soon as it becomes clear that the F9 first stage is recoverable. If there was a launch where four engines failed, SpaceX is going to want to try and recover the first stage (assuming the centre engine isn't one of them!). You'd simply keep the engines firing to burn off the propellant; launch the second stage and then try to land!I don't think planning for the kind of failure you cite is worth it. Losing four engines is very unlikely. Instead the effort should go into improving the reliability of the vehicle so aborts become less likely in the first place.Unlikely things happen! (And there may be other more likely causes of LoM; a four-engine failure was something I came up with off the top of my head.) But it's a question of economics; efforts in improving reliability run into diminishing returns, at some point there is a crossover as to where further resources should be spent. No doubt someone will run the figures. But SpaceX has a Silicon Valley mindset, part of which is the Japanese concept of kaizen or continuous improvement. And the F9 is a research and development vehicle as much as an operational one; best to learn how to do these things before moving on to bigger and more valuable launchers! QuoteThe correct way to go in the event of first stage engine failure is to abort the first stage recovery sequence to recover the margin needed to allow the second stage and payload to achieve orbit.Really? Or is this another of those items of received wisdom developed in an era of expendable launchers? For example, if it's a cargo Dragon, the first stage could be worth more than the second stage, capsule and cargo combined! Given that the Dragon and cargo are probably recoverable as well, would it not make financial sense to abort the mission; recover the first stage and relaunch the cargo later? (If the payload is a satellite, the opposite might well be true, but horses for courses.)
(If the payload is a satellite, the opposite might well be true, but horses for courses.)
Really? Or is this another of those items of received wisdom developed in an era of expendable launchers?
Crazy idea number 37:
Quote from: CuddlyRocket on 11/03/2013 05:34 pmReally? Or is this another of those items of received wisdom developed in an era of expendable launchers? Yes, really. And it isn't "received wisdom." It's common sense as opposed to wishful thinking.
F9R in its presently conceived form (even with recovery of both stages) cannot recover the payload in the event of an abort.
To put any effort into abort scenarios when you are going to lose the payload is waste of effort. The effort should go into increasing reliability so the possibility of abort is reduced in the first place. (And that makes it more likely you're going to recover the first stage successfully too.)
Payload abort recovery is a capability for a future vehicle. So we are talking about something which should be in advanced concepts.
Why are we discussing this? This is impossible. A rocket that has a design with legs rated for a full vehicle load won't be making it to orbit with any reasonable payload.
Not to mention that after any kind of flight path is flown, returning to launch site becomes impossible because of lack of fuel.
Not to mention if a flight path change is attempted while in the atmosphere the vehicle will break up.
Can we close this?
Quote from: douglas100 on 11/04/2013 08:58 amQuote from: CuddlyRocket on 11/03/2013 05:34 pmReally? Or is this another of those items of received wisdom developed in an era of expendable launchers? Yes, really. And it isn't "received wisdom." It's common sense as opposed to wishful thinking.Being trained as a scientist, I am wary of arguments based on common sense, as they frequently turn out not to be sensible even if common. I gave an argument why it may not be as sensible in this case as you suppose, which you signally failed to address.
QuotePayload abort recovery is a capability for a future vehicle. So we are talking about something which should be in advanced concepts.I don't agree with the first sentence. And are different ways of using existing vehicles really advanced concepts?
Quote from: mlindner on 11/05/2013 12:39 amWhy are we discussing this? This is impossible. A rocket that has a design with legs rated for a full vehicle load won't be making it to orbit with any reasonable payload.Nobody's suggesting this. Well, at least I'm not - I assumed that landing legs would be designed for a nearly empty vehicle. This does mean you'd have to consider whether burn off of excess propellant is possible.
QuoteNot to mention if a flight path change is attempted while in the atmosphere the vehicle will break up.Best not do it in the atmosphere then. Or reduce speed sufficiently first.
Look, I'm not saying that recovery in an abort is easy; just that it may not be impossible, and if not impossible then it's worth looking at because millions of dollars could be saved.
QuoteCan we close this?If you're not interested just don't read the thread! Why propose short-circuiting things for other people who may be?
...Why is it an either/or?...
Hmm, what about recovering only the second stage with the payload in case of a first stage failure. Obviously not as neat as recovering the entire rocket, but maybe more plausible?
Quote from: bioelectromechanic on 11/01/2013 06:08 pmI was thinking a F9R could use it's ability to land to abort a failed launch. E.g if an F9R suffers an early stage engine loss, or later double engine loss.What would be needed to be done to allow it to land with a 2nd stage plus payload on top?My first thought was it needs to vent a huge amount of propellant to avoid overloading the legs during landing. It is a non starter. It would need stronger legs for the added weight of upperstage, payload and fairing. Vent is a misnomer. It has to get rid of the propellant fast and guess what? It can't get rid of it faster than burning it through the engines. That includes the upperstage propellant. And then there is the spacecraft. Not to mention the that whole vehicle has to be able to take the new aeroloads from the pitch around maneuver. That means strengthened interstage and fairing. Also, there now is a live payload, with toxic and hazardous propellant onboard with no ability to command it if using current conops (typically, there is no electrical or rf interaction between spacecraft and LV except for breakwires, and maybe some occasion discreets )This would require a whole redesign of the vehicle
What about a water recovery, after stage separation?There might be value in recovering a stage for fault diagnosis and partial reuse.
Perhaps (?!) the payload could survive and be recovered, and it's the most valuable piece of the rocket...
Not all failures are graceful.
It's interesting how arguments continue even when its been accepted that the thing being argued about is impossible.
Quote from: mlindner on 11/10/2013 04:07 amIt's interesting how arguments continue even when its been accepted that the thing being argued about is impossible....impossible isn't accurate. Someday, reusable launch vehicles /will/ have intact abort capability.
Quote from: Robotbeat on 11/11/2013 02:07 amQuote from: mlindner on 11/10/2013 04:07 amIt's interesting how arguments continue even when its been accepted that the thing being argued about is impossible....impossible isn't accurate. Someday, reusable launch vehicles /will/ have intact abort capability.I'll very certain that they won't.Payloads - maybe. Maybe some.Vehicles? I can't see how or why.
Quote from: meekGee on 11/11/2013 02:20 amQuote from: Robotbeat on 11/11/2013 02:07 amQuote from: mlindner on 11/10/2013 04:07 amIt's interesting how arguments continue even when its been accepted that the thing being argued about is impossible....impossible isn't accurate. Someday, reusable launch vehicles /will/ have intact abort capability.I'll very certain that they won't.Payloads - maybe. Maybe some.Vehicles? I can't see how or why.Sigh... People in this thread keep talking across each other with different assumptions (F9R vs future RLV).And MeekGee, you really cant imagine a future SSTO RLV with intact abort? (That's pretty much what it would take) It seems pretty narrow minded to exclude such a possibility.