Global Prompt Strike using a Reusable LV.

[Forest Green]

It all depends how wide the warhead bus is. Payload is irrelevant if the bus only has enough area for X warheads.

 

[Yellow Palace]

It may be able to support somewhat heavier RVs, but it's still going to max out at 3 (assuming a MM3 OML as concepts have used).

So I think Sentinel is going to be longer ranged due to lighter stages.

FWIW, back in 1975, RAND reckoned that a missile using then-current technology - that is, the Peacekeeper technological base - would have double the throw-weight for the same (6,000 nautical mile) range.

It stands to reason that a modern missile would be at least equivalent.

 

[Byeman]

Come on now, a SSTO Spaceplane is hardly warp drive level. It's basically doable, it's just that nobody has poured the cash into it yet.

No, it isn't/. Not with chemical rockets. Just a stage with no payload, possible. With payload and wings, no way.

 

[Byeman]

If you RTLS over land,

It is not even RTLS, it is launching in the first place over inhabited land. Chinese or Middle East don't count. Western world values are at play here.

 

[Byeman]

It may be able to support somewhat heavier RVs, but it's still going to max out at 3 (assuming a MM3 OML as concepts have used).

So I think Sentinel is going to be longer ranged due to lighter stages.

or longer range

 

[martinbayer]

Come on now, a SSTO Spaceplane is hardly warp drive level. It's basically doable, it's just that nobody has poured the cash into it yet. A warp drive requires negative mass, which hasn't even been discovered yet, to even hold together even the faintest dream of it ever being a reality.

That is exactly why NASA came up with TRLs.

 

[Forest Green]

No, it isn't/. Not with chemical rockets. Just a stage with no payload, possible. With payload and wings, no way.

Someone disagrees apparently.

Radian One unveils plans for single-stage to orbit spaceplane

A new company has entered the commercial space race. Startup Radian Aerospace has emerged from stealth to announce it has secured US$27.5 million in seed funding to develop a single-stage to orbit (SSTO) spaceplane called Radian One, which is designed to lift and land horizontally.

newatlas.com

Radian Aerospace – World’s First Single-Stage-to-Orbit Spaceplane

Radian Aerospace is building a next-generation spaceplane planned to be the world's first single-stage-to-orbit, truly reusable space vehicle operating in Low Earth Orbit.

www.radianaerospace.com

https://www.secretprojects.co.uk/threads/radian-ssto-spaceplane.38692/

 

[Byeman]

Someone disagrees apparently.

Radian Aerospace – World’s First Single-Stage-to-Orbit Spaceplane

Radian Aerospace is building a next-generation spaceplane planned to be the world's first single-stage-to-orbit, truly reusable space vehicle operating in Low Earth Orbit.

www.radianaerospace.com

This is not an SSTO. A sled on a track is a stage.
Ha! "A revolutionary 2-mile-long rail sled system eliminates the constraints of vertical systems" and adds more of its own like requiring a launch flat launch area and limited launch azimuths.
5000lb payload? Not very competitive.

 

[Forest Green]

This is not an SSTO. A sled on a track is a stage.
Ha! "A revolutionary 2-mile-long rail sled system eliminates the constraints of vertical systems" and adds more of its own like requiring a launch flat launch area and limited launch azimuths.
5000lb payload? Not very competitive.

It would need a 2 mile long runway as any large aircraft, even a 747 needs that, so not really a constraint. There's also the Skylon, plus advancements in RDE scramjets and rockets, which are vastly more efficient than traditional rockets.

Watch NASA test revolutionary new rotating detonation rocket engine (video)

Texas-based startup Venus Aerospace clears a major hurdle in its new reusable hypersonic engine technology.

www.space.com

The world’s first space flight for the rotating detonation engine, and a glimpse at a new sample return capsule

As with all sounding rockets, the flight was brief and the 8m long rocket dropped into the sea eight minutes after launch. Splashing down alongside the rocket were records of the flight on a chip embedded in JAXA’s newest re-entry capsule. That data would reveal that for six seconds above the

cosmos.isas.jaxa.jp

 

[Byeman]

It would need a 2 mile long runway as any large aircraft, even a 747 needs that, so not really a constraint. There's also the Skylon, plus advancements in RDE scramjets and rockets, which are vastly more efficient than traditional rockets.

It would need a larger area than an airport
Skylon? Might as well had said fusion power, it just around the corner too.
A little more ISP from RDE is not going to change things. Max ISP is still limited.
Scramjets? They are also around the corner, but they are useless for space launch. Not enough time is spent in the atmosphere to make use of them or too much time and the craft will need TPS similar to what is required for entry.

 

[trose213]

Would probably make more sense doing Rods from God with Starship

 

[Forest Green]

It would need a larger area than an airport

That comment makes no sense. Some airports have 3 mile long runways, often more than one too, plus taxiways.

It would need a larger area than an airport
Skylon? Might as well had said fusion power, it just around the corner too.
A little more ISP from RDE is not going to change things. Max ISP is still limited.

25% seems a decent amount.

Rotating detonation engine - Wikipedia

en.wikipedia.org

 

[Byeman]

That comment makes no sense. Some airports have 3 mile long runways, often more than one too, plus taxiways.

25% seems a decent amount.

Rotating detonation engine - Wikipedia

en.wikipedia.org

Not for H2 and O2. RS-25 and RL10 are already near the maximum possible. And that is for all chemical rocket that don't use Florine or Beryllium (or other toxic substances)

 

[Forest Green]

Not for H2 and O2. RS-25 and RL10 are already near the maximum possible. And that is for all chemical rocket that don't use Florine or Beryllium (or other toxic substances)

You sure about that?

https://thephysicsofspacex.wordpress.com/wp-content/uploads/2016/07/isp-upper-limits.pdf

https://ntrs.nasa.gov/api/citations/20210009939/downloads/Review%20of%20AM%20RDRE%20Injectors.pdf

The biggest improvement is with air-breathing performance though.

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1043&context=usafresearch

 

[Byeman]

You sure about that?

https://thephysicsofspacex.wordpress.com/wp-content/uploads/2016/07/isp-upper-limits.pdf

https://ntrs.nasa.gov/api/citations/20210009939/downloads/Review%20of%20AM%20RDRE%20Injectors.pdf

yes, because can't fix the losses like:
Where does the remaining energy go? Some is stored in the motion of the exhaust: in intramolecular vibrations and rotations, and kinetic energy in directions perpendicular to the rocket’s travel. Some is also used to heat (and boil) the two cryogenic liquids from their stored temperature to their combustion one (a quick estimate factoring in only latent heat of vaporisation of oxygen brings the upper bound down to 520s)."

also, to heat some LOX and LH2 into GOX and hot H2 to pressurize the External tank.

The point is that ISP can't improved enough to make a reusable SSTO with wings viable.

 

[Forest Green]

yes, because can't fix the losses like:
Where does the remaining energy go? Some is stored in the motion of the exhaust: in intramolecular vibrations and rotations, and kinetic energy in directions perpendicular to the rocket’s travel. Some is also used to heat (and boil) the two cryogenic liquids from their stored temperature to their combustion one (a quick estimate factoring in only latent heat of vaporisation of oxygen brings the upper bound down to 520s)."

also, to heat some LOX and LH2 into GOX and hot H2 to pressurize the External tank.

The point is that ISP can't improved enough to make a reusable SSTO with wings viable.

According to NASA the RDREs have 15% better Isp but the RDREs themselves are more compact, which reduces mass.

It is commonly cited that the peak benefit to detonative combustion devices is the promised ~15% boostin specific impulse (Isp) compared to the maximum theoretical Isp in an equivalent constant pressure (CP)combustor. However, other major performance characteristics are advantages with these engines ratherthan quantities such as Isp and thrust. For one, these engines are often much more compact allowing forreduced hardware mass a geometry. The completion of combustion has been shown to occur much fasterthan CP combustors and thus drastically reduces L* requirements as well as the potential to maximizecharacteristic velocity (C*) efficiency. Other works have suggested that these combustion devices couldproduce lower overall heat fluxes and lower total heat load to active cooling geometries. In addition, lessonslearned from the literature indicates that the heat flux curve in a detonative combustor may decrease as theflow gets closer to the chamber exit. This would allow for the design of ultra-low pressure drop integratedcoolant channels, which is another major performance advantage for this engine type. Each of theseperformance criteria make a strong case for investment into detonative combustion device technologies.

Then you have the possibility to use air-breathing RDE operation in atmosphere, where an Isp of 3,800-5500s can be achieved.

https://www.sciencedirect.com/science/article/abs/pii/S0360319915009842

I don't think we can rule out viability yet, but it may never be competitive for commercial space launch.

 

[Byeman]

According to NASA the RDREs have 15% better Isp but the RDREs themselves are more compact, which reduces mass.

still not going to help enough.

 

[Forest Green]

There's no way we could know that. Smaller engines mean smaller body around engines, both of which save massive weight, which means smaller wings, which saves more weight + reduced cooling weight + higher rocket Isp + massively higher air-breathing Isp. Lot of gains there.

Don't think we can even nearly rule out viability, but whether it will be commercially viable is another question.

 

[Byeman]

There's no way we could know that. Smaller engines mean smaller body around engines, both of which save massive weight, which means smaller wings, which saves more weight + reduced cooling weight + higher rocket Isp + massively higher air-breathing Isp. Lot of gains there.

Don't think we can even nearly rule out viability, but whether it will be commercially viable is another question.

yes, we can. The margins are so slim even for an expendable one. And no, it is not saving "massive" weight and hence not "lot of gains". A Raptor engine only weighs 3,500 lbs. It wouldn't be much smaller. More compact RDE is inches and not feet. The nozzle dominates the length of the engine, the combustion chamber is a fraction of it.