X-30 Question

[SRB]

AFAIK, the X-30 SSTO/TAV was supposed to just use air-breathing engines to reach Mach 25 and orbit, while the similar HOTOL SSTO/TAV would use both air-breathing and rocket engines, which makes sense to me because air-breathing engines are useless in space.

so, how was the X-30 supposed to work?

[Scotius]

https://en.wikipedia.org/wiki/Skylon_(spacecraft)

Depends on the type of air-breathing engine

[SRB]

Thanks, but this: https://en.wikipedia.org/wiki/Rockwell_X-30 mentions it’s one engine being a scramjet.

Even if it got up to space just on the scramjet, it would still need some sort of OMS to get to  circularize its  orbit

[wumpus]

What you got was the X-43 project (I've posted quite a bit on that, but I doubt this forum has a good way to search for them).

It did show that sustained flight at mach 6.8 was a real possibility.  I forgot the whole range of flight, but this one proved somewhat realistic (assuming a "payload" containing just enough hydrogen to produce the required acceleration is enough).

It also showed that mach 9.6 was a real possibility, although to get there it had to be boosted to mach 9.6 and have the center of the error bars of the acceleration *just* on the positive side of zero.  Don't expect to actually hit mach 9.6 from barely supersonic speed without a ton of R&D.

This project begat the X-51 project, which appears (as an Air Force project expect most of it to be classified) to get to mach ~6 on "jet fuel".  Unfortunately this jet fuel is JP-7, the cost is best described as "similar to a good scotch".  I don't know if that is the scotch the technicians drink, or the scotch the Air Force generals drink when being liquored up by beltway bandits.  Either way, it is far, far, more expensive than hydrogen (although it might even fit in a reasonable fuel tank).

[DDE]

13 hours ago, wumpus said:

This project begat the X-51 project, which appears (as an Air Force project expect most of it to be classified) to get to mach ~6 on "jet fuel".  Unfortunately this jet fuel is JP-7, the cost is best described as "similar to a good scotch".  I don't know if that is the scotch the technicians drink, or the scotch the Air Force generals drink when being liquored up by beltway bandits.  Either way, it is far, far, more expensive than hydrogen (although it might even fit in a reasonable fuel tank).

This hasn’t ever stopped the people on the other side of the Iron Curtain from coming with increasingly exotic fuels for increased energy density of cruise missile propellants.

Culminating, as we’re told, in uranium-235.

On 5/26/2019 at 4:52 PM, ErinBensen said:

AFAIK, the X-30 SSTO/TAV was supposed to just use air-breathing engines to reach Mach 25 and orbit, while the similar HOTOL SSTO/TAV would use both air-breathing and rocket engines, which makes sense to me because air-breathing engines are useless in space.

so, how was the X-30 supposed to work?

It wasn't.

The thing with many SSTO development programs is that they throw in suborbital stepping stone designs with extant utility, such as, in X-30’s case, a Transatlantic airliner, or in Tu-2000’s case (oh hell yeah the Soviets decided to mirror the X-30) the Tu-360 bomber. I am entirely, absolutely confident DoD didn’t have similar plans for the X-30. What’s SR-72, anyway?

Subsequent designs would integrate hydrolox or, in M-19’s case, nuclear engines for the final kick.

 

Edited May 27, 2019 by DDE

[SRB]

9 minutes ago, DDE said:

This hasn’t ever stopped the people on the other side of the Iron Curtain from coming with increasingly exotic fuels for increased energy density of cruise missile propellants.

Culminating, as we’re told, in uranium-235.

It wasn't.

The thing with many SSTO development programs is that they throw in suborbital stepping stone designs with extant utility, such as, in X-30’s case, a Transatlantic airliner, or in Tu-2000’s case (oh hell yeah the Soviets decided to mirror it) the Tu-360 bomber. I am entirely, absolutely confident DoD didn’t have similar plans for the X-30.

Would this airliner be the Orient Express that could go IAD-NRT in 2 hours?

[DDE]

Just now, ErinBensen said:

Would this airliner be the Orient Express that could go IAD-NRT in 2 hours?

Precisely.

A certain British design is undergoing similar permutations.

[SRB]

1 minute ago, DDE said:

Precisely.

A certain British design is undergoing similar permutations.

https://en.wikipedia.org/wiki/Skylon_(spacecraft) and https://en.wikipedia.org/wiki/Reaction_Engines_A2

[wumpus]

3 hours ago, DDE said:

This hasn’t ever stopped the people on the other side of the Iron Curtain from coming with increasingly exotic fuels for increased energy density of cruise missile propellants.

Culminating, as we’re told, in uranium-235.

Considering that a cruise missile's mission is primarily flying low across a long range of terrain and has a single use engine, it takes some pretty exotic fuel to nudge the price of the project at all, no matter how many you make.

U-235?  Since such a thing would presumably be carrying nuclear weapons anyway, I'd assume that putting fairly refined uranium into a device that occasionally gets shot down isn't *that* stupid, but sooner or later some joker of a president will want to use one for a conventional payload in a place where Iran (or similar nation with nuclear ambitions) might get one.

I thought the "uranium bomber" was supposed to be manned.  And polluting the country it flew over was assumed a plus, at least until somebody asked how you would train the flight crew (it may have originally been conceived as a cruise missile, but before the guidance systems needed for such things were developed).

[Guest]

No, Burevestnik was unmanned from the start, and is a modern project anyway. I don't recall any Soviet forays into this tech. The SLAM (aka Project Pluto) was never manned, either. Actual nuclear-powered bombers wouldn't have polluted anything, thanks to their shielded reactors.

Edited May 27, 2019 by Guest