A key aspect of Starship is orbital refueling for Mars missions, so it has to have full and rapid reusability for tanker operations.New Glenn is for putting payloads into orbit. Blue needs reusability, but it doesn't have to be rapid.Elon recently said Starship development would have been easier if it was a little smaller than its 9 m diameter. New Glenn is 7 m. Jarvis just might be the right size for its job.
“Rapid” is a crucial part of cheap. It means more uses over a given time period, meaning fixed costs get split across a higher number of launches. See SLS for the opposite extreme, where fixed costs have a very low number of launches to be allocated to per year.Elon’s measure of performance is something along the lines of “tonnage to orbit per vehicle per time period”.
Any advantages for a reusable new-glenn with a shortened booster that stages earlier to enable more rapid reuse?
Quote from: hektor on 07/27/2021 01:51 pmWasn't there already a rocket called Jarvis?Yes. It was an Air Force/NASA launch vehicle concept in the ‘80s named after Greg Jarvis.
Wasn't there already a rocket called Jarvis?
Quote from: gin455res on 07/28/2021 06:52 amAny advantages for a reusable new-glenn with a shortened booster that stages earlier to enable more rapid reuse?Don't see any benefit; more disadvantages. If you are thinking it will reduce down-range landing distance, and thus recycle time, that is unlikely to make a significant difference. Or just use the propellant available in the larger booster to reduce the down-range distance (likely better than having two different boosters).Return to launch site (RTLS) would make a more significant difference, but that argues for more propellant and thus a larger booster--or consequent payload reduction--not a smaller booster. For a given payload-orbit, if the booster stages lower-slower, the second stage will have to make it up. No free lunch here.Or are you thinking along different lines?
Quote from: RonM on 07/28/2021 03:27 amA key aspect of Starship is orbital refueling for Mars missions, so it has to have full and rapid reusability for tanker operations.New Glenn is for putting payloads into orbit. Blue needs reusability, but it doesn't have to be rapid.Elon recently said Starship development would have been easier if it was a little smaller than its 9 m diameter. New Glenn is 7 m. Jarvis just might be the right size for its job.“Rapid” is a crucial part of cheap. It means more uses over a given time period, meaning fixed costs get split across a higher number of launches. See SLS for the opposite extreme, where fixed costs have a very low number of launches to be allocated to per year.Elon’s measure of performance is something along the lines of “tonnage to orbit per vehicle per time period”.
[...] this sounds like a knee jerk, disjointed attempt to shoehorn a reusable upper stage onto a pre-existing rocket designed for only partial reusability.
Quote from: M.E.T. on 07/28/2021 01:56 am[...] this sounds like a knee jerk, disjointed attempt to shoehorn a reusable upper stage onto a pre-existing rocket designed for only partial reusability.This looks like knee-jerk criticism to me, from someone who is sour on the company for other reasons. Want to make a rocket that's fully re-usable? Start with a rocket whose first stage is already re-usable, and is big enough for a useful payload even after the second stage re-usability is factored in (that's one of the main reasons SpaceX did not pursue re-usability of the F9 second stage).The job of the first stage is to deliver the appropriate mass to the right speed, altitude, and angle. These need to be decided very early in a project anyway, even if the design is an integrated effort. And once the are decided, the second stage can be designed. It's no more shoehorning in one case than the other.Using an existing component is good engineering. SpaceX was forced to design a new first stage to pursue full re-usability, because they did not have a first stage big enough. They may well have over-done it (Musk has stated that maybe 9 meters was too big, as it makes development more difficult). Blue has an existing first stage of the right size - it makes sense to use it.Finally, suppose you wanted to design, from scratch, a fully re-usable rocket of 7 meter diameter (as Musk himself has suggested might be better than what SpaceX is doing). What design decisions would you make that differ from what Blue is doing? You could argue for common materials, common engines, or common fuels, but none of these are slam dunks. Each involves sacrificing some optimization for the sake of commonality. Rockets have traditionally gone in the other direction, so it's not an obvious engineering error.Blue (as you point out) has a number of other challenges. This approach is not one of them.
[...] The job of the first stage is to deliver the appropriate mass to the right speed, altitude, and angle. [...]
Quote from: LouScheffer on 07/28/2021 12:32 pmFinally, suppose you wanted to design, from scratch, a fully re-usable rocket of 7 meter diameter (as Musk himself has suggested might be better than what SpaceX is doing). What design decisions would you make that differ from what Blue is doing? You could argue for common materials, common engines, or common fuels, but none of these are slam dunks. Each involves sacrificing some optimization for the sake of commonality. Rockets have traditionally gone in the other direction, so it's not an obvious engineering error.Blue (as you point out) has a number of other challenges. This approach is not one of them.Well jeez, you dismiss common materials, common engines and common fuels. Guess that doesn’t leave much of the rocket to discuss, does it🤷♂️
Finally, suppose you wanted to design, from scratch, a fully re-usable rocket of 7 meter diameter (as Musk himself has suggested might be better than what SpaceX is doing). What design decisions would you make that differ from what Blue is doing? You could argue for common materials, common engines, or common fuels, but none of these are slam dunks. Each involves sacrificing some optimization for the sake of commonality. Rockets have traditionally gone in the other direction, so it's not an obvious engineering error.Blue (as you point out) has a number of other challenges. This approach is not one of them.
Quote from: M.E.T. on 07/28/2021 01:49 pmQuote from: LouScheffer on 07/28/2021 12:32 pmFinally, suppose you wanted to design, from scratch, a fully re-usable rocket of 7 meter diameter (as Musk himself has suggested might be better than what SpaceX is doing). What design decisions would you make that differ from what Blue is doing? You could argue for common materials, common engines, or common fuels, but none of these are slam dunks. Each involves sacrificing some optimization for the sake of commonality. Rockets have traditionally gone in the other direction, so it's not an obvious engineering error.Blue (as you point out) has a number of other challenges. This approach is not one of them.Well jeez, you dismiss common materials, common engines and common fuels. Guess that doesn’t leave much of the rocket to discuss, does it🤷♂️By "common", I meant the same in the two stages, not the "common" as found in everyday life. Do the two stages have to have the same fuels? No, many rockets use different fuels for different stages. Must the stages be built of the same materials? No, Atlas and Vulcan use aluminum for the first and steel for the second. Do the stages need to use common engines? No, only SpaceX does this, and they are not common, just closely related. And each of these choices has corresponding advantages/disadvantagesMy point is that these are things you *could* do if you design as a unit. But it's far from obvious they are needed, or even optimum, as many successful rockets have chosen differently.
By "common", I meant the same in the two stages, not the "common" as found in everyday life. Do the two stages have to have the same fuels? No, many rockets use different fuels for different stages. Must the stages be built of the same materials? No, Atlas and Vulcan use aluminum for the first and steel for the second. Do the stages need to use common engines? No, only SpaceX does this, and they are not common, just closely related. And each of these choices has corresponding advantages/disadvantagesMy point is that these are things you *could* do if you design as a unit. But it's far from obvious they are needed, or even optimum, as many successful rockets have chosen differently.
Quote from: LouScheffer on 07/28/2021 02:53 pmBy "common", I meant the same in the two stages, not the "common" as found in everyday life. Do the two stages have to have the same fuels? No, many rockets use different fuels for different stages. Must the stages be built of the same materials? No, Atlas and Vulcan use aluminum for the first and steel for the second. Do the stages need to use common engines? No, only SpaceX does this, and they are not common, just closely related. And each of these choices has corresponding advantages/disadvantagesMy point is that these are things you *could* do if you design as a unit. But it's far from obvious they are needed, or even optimum, as many successful rockets have chosen differently.None of these successful rockets can compete with Falcon 9 in terms of cost.
Quote from: su27k on 07/28/2021 03:18 pmQuote from: LouScheffer on 07/28/2021 02:53 pmBy "common", I meant the same in the two stages, not the "common" as found in everyday life. Do the two stages have to have the same fuels? No, many rockets use different fuels for different stages. Must the stages be built of the same materials? No, Atlas and Vulcan use aluminum for the first and steel for the second. Do the stages need to use common engines? No, only SpaceX does this, and they are not common, just closely related. And each of these choices has corresponding advantages/disadvantagesMy point is that these are things you *could* do if you design as a unit. But it's far from obvious they are needed, or even optimum, as many successful rockets have chosen differently.None of these successful rockets can compete with Falcon 9 in terms of cost.True, but I believe most of this is due to re-usability, not common engines or materials. For example, F9 might be better off with a steel first stage (higher performance for the same or less cost), as it would require less fuel reserved for re-entry since it's more temperature resistant. Likewise methane engines, since they appear to run cleaner and require less refurbishment, something that does not apply to the second stage. SpaceX uses carbon fiber for the interstage, even though it's the exact same diameter as the first and second stage and could be produced from aluminum on common tooling. And vacuum Merlins are quite different, though obviously related.So until someone else gives reusability a good solid try, it's hard to separate the effect of reusability and common technology. As of now, there are at least two unknowns and only one measurement.