Evolved DC-X

[RanulfC]

Oh and in case folks missed the connection, the Masten design is VERY similar to the 'evolved-DC-X' concepts that were being tossed around as boosters for the "Hot Eagle" concepts

Randy

[TrevorMonty]

The Masten design looks a lot like ESA IXV, which is capable of LEO reentry speeds.

https://en.m.wikipedia.org/wiki/Intermediate_eXperimental_Vehicle

I don't see this vehicle being used as SSTO. But it does give DARPA a very useful reuseable test vehicle, this maybe reason for Mach 10 requirement.

As I understood it the Mach-10 requirement was both experimental, as well as operational since Mach 10 staging makes for a really small upper stage allowing for one that might fit into a payload bay on the booster. (Yes, that's a 'thing" as the military like the idea of 'minimum-mass,' non-aerodynamic upper stage concepts either partially or fully enshrouded on the booster)

Randy

So this vehicle can do multiple roles.
1) RLV for small upper stage and with small satellites staging at mach 10.
2) RLV for larger upper staging at  <Mach 10.
3) RLV for deploying experimental vehicles at hypersonic speeds.

I can see NASA also finding use for it as 3).

Masten would most likely be responsible for operating and maintaining a XS1 for DOD. This would give them a regular income, while still operating their own vehicles for commercial purposes.

[Oli]

You might want to read the whole thing and especially the discussion and conclusion section again. Mach-3 staging is HIGHLY "marginal" as it requires the largest, most expensive upper stage.

I never said Mach 3 staging is not marginal, it's the delta-v you save from glide back that is not marginal.

Not at all and the thesis you cite in fact points that out. The higher the staging velocity the further down-range the booster will reenter and the harder it is to flyback, and the more the booster mass grows. (Page 27 figure 22) "Optimal" is around Mach-6 and the highest is only a bit over Mach-8.

I said "The higher the staging velocity the better is fly back.", that means compared to other methods fly back does better at higher staging velocities.

[joema]

....Mach-3 staging is HIGHLY "marginal" as it requires the largest, most expensive upper stage...

That's correct, as can be seen in this graph I annotated of ideal staging velocity of two-stage launch vehicle vs gross liftoff mass. From "Propulsion and Staging Considerations for an Orbital Sortie Vehicle (Stengel, 1987). Overlayed are the data points for a Mach 7 vs Mach 12 booster. If the booster is not Mach 7 or above, the total vehicle mass -- not just the upper stage -- is huge.

This is counter intuitive since it feels like an air launch or any kind of initial modest boost would help a lot. But what it produces is a gigantic upper stage which in turn requires an even more gigantic reusable lower stage to lift.

https://photos.smugmug.com/photos/i-nKLmZSR/0/O/i-nKLmZSR.jpg

[Elmar Moelzer]

If the booster is not Mach 7 or above, the total vehicle mass -- not just the upper stage -- is huge.

Isn't the Falcon9 staging at about Mach 6 when they do RTLS?

[TrevorMonty]

....Mach-3 staging is HIGHLY "marginal" as it requires the largest, most expensive upper stage...

That's correct, as can be seen in this graph I annotated of ideal staging velocity of two-stage launch vehicle vs gross liftoff mass. From "Propulsion and Staging Considerations for an Orbital Sortie Vehicle (Stengel, 1987). Overlayed are the data points for a Mach 7 vs Mach 12 booster. If the booster is not Mach 7 or above, the total vehicle mass -- not just the upper stage -- is huge.

This is counter intuitive since it feels like an air launch or any kind of initial modest boost would help a lot. But what it produces is a gigantic upper stage which in turn requires an even more gigantic reusable lower stage to lift.

https://photos.smugmug.com/photos/i-nKLmZSR/0/O/i-nKLmZSR.jpg

Are these figures for expendable or reusable booster?.