Two-stage Spaceplane with LOX collection

[Nibb31]

2 hours ago, RuBisCO said:

What matters more is turn around time, maintenance and launch costs.

As well as hardware acquisition and R&D.

[magnemoe]

6 minutes ago, MatterBeam said:

I agree with your statement on fuel costs but the 300 mission figure I gave out was only to divide full cost of the vehicle over its service lifetime to provide a fairer price/kg comparison with expendable rockets. The only 'need' is for components to be used for more than one mission for them to massively win out against expendable rockets. Like the Falcon 9 booster: even if it only survives for 3 missions, it has already massively won out in prices against every single other rocket out there.

I'm confused however by the 1km/s figure? I thought it was clear that the booster plane did not stage at Mach 3, but after switching to rocket mode and reach 3km/s and an altitude of over 100km. 

It is extremely hard to make ramjets in a vertical launch vehicle useful. The traditional gravity turn launch trajectory gives them a very very small window of usefulness before the atmosphere becomes too thin.

yes, it was 2 or 3 km/s, you could stage at 1 km/s however this would be in atmosphere and also make upper stage larger. 2 km/s is more common. 
One issue with having upper stage in front is that you don't want takeoff wheels on the upper stage, it would need to be far more beefy than needed for landing an probably longer too. 

[wumpus]

26 minutes ago, MatterBeam said:

I agree with your statement on fuel costs but the 300 mission figure I gave out was only to divide full cost of the vehicle over its service lifetime to provide a fairer price/kg comparison with expendable rockets. The only 'need' is for components to be used for more than one mission for them to massively win out against expendable rockets. Like the Falcon 9 booster: even if it only survives for 3 missions, it has already massively won out in prices against every single other rocket out there.

First, you would be already be competing against reuseable rockets.  They exist today, and any "fuel efficient" rocket is decades away from being economical.  Second, non-reusable rockets are used because they really *are* economical, especially compared to exotic 'three use' boosters containing jet engines.  Compare the Space Shuttle costs vs. virtually any expendable rocket and you will find that the reusable one loses in costs.  You're building a rocket with "shuttle level" costs (especially considering those wings), not a falcon 9 which is still pretty cheap when expended in a single use.

If it has a "rocket mode", why bother with compressors?  They are spectacularly expensive and have to be bypassed once you go much over supersonic.  Finally if you can't support vertical flight (or at least a standard launch profile, I'd dump the jets and look into air-augmented rockets.  Air-breathers only help to 1km/s, but wings have to be carried to staging (and again, if you have a "rocket mode" you can land vertically).

[KSK]

11 hours ago, RuBisCO said:

Look at the weight of the space shuttle, ~25 tons of cargo to orbit with a on pad weight of 2,030 tons. 

No, my proposal is simply a fully reusable space shuttle, as it had been originally proposed, two winged stages would take-off, first stage would glide back and second stage would enter orbit, drop off cargo and glide back. My belief is had they actually built that, instead of the semi-reusuable POS they created, the space-shuttle would not have been the utter failure it had become.

Or NASA would have wound up trying to develop, build and fly two expensive, high performance, highly experimental aircraft/spacecraft, instead of one.

Dry mass of the Orbiter was around 80 tons. That's a lot of mass overhead for your 25 tons of cargo and it's not even factoring in propellant mass. Even being generous and assuming an 80 tons dry mass including cargo, to get that up to the staging altitude and speeds being bandied around on this thread would require a booster plane with the carrying capacity of a C5 Galaxy and the performance of an SR-71.

And all that to throw an unfueled spaceplane over the Karman line if you're lucky.

[DerekL1963]

1 hour ago, Nibb31 said:

As well as hardware acquisition and R&D.

Yup, it's not just minimizing direct costs...  It's also minimizing overhead and then amortizing that overhead across a large number of flights per vehicle - not just total lifetime flights, but also keeping the daily tempo maximized so that any given aircraft spends as little time on the ground not earning money as possible.

That is the real barrier to low cost reusable launches, reaching and maintaining that high tempo.

And that high tempo brings safety and reliability issues the space industry hasn't even begun to think about addressing.  If airliners were as unsafe as rockets, Sea-Tac alone would have a crash on takeoff one of two times a day.  Seriously, what the space industry accepts as business as usual in terms of accidents and loss would be considered horribly unsafe by any other standard.

[RuBisCO]

On 8/10/2017 at 11:11 AM, KSK said:

Or NASA would have wound up trying to develop, build and fly two expensive, high performance, highly experimental aircraft/spacecraft, instead of one.

Dry mass of the Orbiter was around 80 tons. That's a lot of mass overhead for your 25 tons of cargo and it's not even factoring in propellant mass. Even being generous and assuming an 80 tons dry mass including cargo, to get that up to the staging altitude and speeds being bandied around on this thread would require a booster plane with the carrying capacity of a C5 Galaxy and the performance of an SR-71.

And all that to throw an unfueled spaceplane over the Karman line if you're lucky.

Again I'm not talking about a plane, just a rocket, a rocket with wings to glide back to a runway once it has spent its fuel.

 

SpaceX may do even better by replacing the mass and drag of wings with rocket fuel for a controlled vertical landing. So the need to fly through the air on fuel efficient jet engines is non-existent.

Edited August 11, 2017 by RuBisCO

[Steel]

58 minutes ago, RuBisCO said:

Again I'm not talking about a plane, just a rocket, a rocket with wings to glide back to a runway once it has spent its fuel.

 

SpaceX may do even better by replacing the mass and drag of wings with rocket fuel for a controlled vertical landing. So the need to fly through the air on fuel efficient jet engines is non-existent.

This issue here is that rockets are not laterally stable enough to withstand the aerodynamic forces of a glide - you can see it in the footage of some rocket failures, once it deviates more that 10 or 20 degrees away from it's velocity vector it will just break up. Thus, you either end up going for the SpaceX route, or you end up having to strengthen the stage hugely, adding a lot of dead-weight, in order for it to be able to glide.

Edited August 11, 2017 by Steel

[magnemoe]

2 hours ago, Steel said:

This issue here is that rockets are not laterally stable enough to withstand the aerodynamic forces of a glide - you can see it in the footage of some rocket failures, once it deviates more that 10 or 20 degrees away from it's velocity vector it will just break up. Thus, you either end up going for the SpaceX route, or you end up having to strengthen the stage hugely, adding a lot of dead-weight, in order for it to be able to glide.

An SR-71 at cruise speed moving just below 1 km/s has an very short window if one engine fails, if it run on one engine it become fragments very fast. This happened, pilot found himself in just the seat then he recovered, second crew member did not survive. 
In short losing aerodynamic stability at high supersonic speeds is very bad. 

[wumpus]

14 hours ago, magnemoe said:

An SR-71 at cruise speed moving just below 1 km/s has an very short window if one engine fails, if it run on one engine it become fragments very fast. This happened, pilot found himself in just the seat then he recovered, second crew member did not survive. 
In short losing aerodynamic stability at high supersonic speeds is very bad. 

https://www.youtube.com/watch?v=F4KD5u-xkik

This is a link to a Smithsonian video with a SR-71 pilot.  That sounds like what he described as an "unstart" that he claims happened about 100 times and put him in mortal peril every time (although apparently not instantly fatal.  Just don't stop flying the plane when you hit the cockpit glass hard enough to break your visor).  I suspect he knows *exactly* how many unstarts he survived, but you can see him censoring himself for either reasons of propriety or national security.

Obviously, any design should do everything possible to avoid such a situation.

[YNM]

On the talks of stability : I think those long, slender shape of rocket first stages are best handled with drag-inducing mechanism on the back - basically stabilizers. The problem with winged rockets is that the stabilizers have to be smaller; so unless one can make the wings go like SpaceShipOne/Two or something, I doubt having winged vertical rockets is practical.

[RuBisCO]

On 8/11/2017 at 3:48 PM, Steel said:

This issue here is that rockets are not laterally stable enough to withstand the aerodynamic forces of a glide - you can see it in the footage of some rocket failures, once it deviates more that 10 or 20 degrees away from it's velocity vector it will just break up. Thus, you either end up going for the SpaceX route, or you end up having to strengthen the stage hugely, adding a lot of dead-weight, in order for it to be able to glide.

Put wings on it and add under-structure, hence the higher structure to fuel ratio I used, which is typically 5%, not 10%-30%. 

[Alcentar]

It seems to me or the Soviets have long come up with almost the same project called "Spiral", everything new is a well-forgotten old one ??? And the spiral is more effective and daring in appearance.

[YNM]

51 minutes ago, Alcentar said:

It seems to me or the Soviets have long come up with almost the same project called "Spiral", everything new is a well-forgotten old one ??? And the spiral is more effective and daring in appearance.

It's not an SSTO / TSTO, it's Shuttle on a shuttle.

http://www.astronautix.com/s/spiralos.html

And then it evolved into :

http://www.astronautix.com/m/maks.html

It's not the best reusability either...

[wumpus]

4 hours ago, YNM said:

It's not an SSTO / TSTO, it's Shuttle on a shuttle.

http://www.astronautix.com/s/spiralos.html

And then it evolved into :

http://www.astronautix.com/m/maks.html

It's not the best reusability either...

If they wanted to do this, I'd expect the time was during the design of the Tu-22 and the Tu-160 (supersonic heavy bombers).  Don't expect them to provide a delta-v of much more than 500m/s (and you would need a total drag much less than the carrying vehicle to do this).  I doubt that 500m/s is enough to justify all the extra constraints on the carried rocket.

Remember who is building it.  I wouldn't want to have to launch GTO satellites from Baikonur either (of course, why would you put GTO birds up with a craft that has wings?).

[YNM]

21 hours ago, wumpus said:

Remember who is building it.  I wouldn't want to have to launch GTO satellites from Baikonur either (of course, why would you put GTO birds up with a craft that has wings?).

Most of Russian satellites are in Molniya orbits. Those to GTO should just use normal rockets. I'm not sure about Buran.