My idea of using the XB-70

[RJMAZ]

My idea of using the XB-70 as a single stage was a bit different.

The rocket stage would be located between the tails. Aerodynamic fairings would smooth the airflow between forward fuselage and the Rocket. These fairings would be essential to allow mach 3+ launch speeds. Rocket size would be approximately 30-40 ton similar to a SpaxeX Falcon 1 with two stages.

The XB-70 bomb bay between the engines would be filled with a liquid oxygen tank. The liquid oxygen would be injected into the compressor stages of the jet engines as engine cooling and also into the afterburner. It would provide a few minutes of 30-50% thrust boost to accelerate the XB-70 up to Mach 4 and 100,000 feet. I call this the O-burner.

The rocket then ignites. Milliseconds later an upwards ejection system pushes the rocket up and the XB-70 pitches down. This should put a comfortable 3,000kg to LEO.

An advanced version version of the rocket would be a spaceplane with a 4 seat cabin. It would be incredibly lightweight with no heatshield to provide enough Delta-V to get to LEO as a single stage with 500kg of payload (4 passengers). Note that Starship upper stage starts at 5,200km/h and makes it into LEO. So a spaceplane starting at 4,000km/h should be possible without a heatshield. The mass of a heatshield probably wouldn't allow the spaceplane to reach LEO once you add the weight of landing gear and wings.

Now to complete this spaceplane system we must assume Starship has massively reduces the cost of payload into LEO and there will be methane and oxygen fuel depots in orbit. The spaceplane can then refuel in orbit and this fuel instead of the heatshield is used to propulsively slow down. We now have a spaceplane system that takes off from an normal airport and allows 4 passengers to reach LEO and return to the same airport.

 

[flateric]

May be first stage, not a 'single stage'?

 

[RJMAZ]

Yes. My post was originally in the "XB-70: Use as a first-stage" thread. Some context has now been lost. I am not suggesting the XB-70 will come back to life. This was is regards to the official 1970's idea/proposals of using the XB-70 for light satellite launches. There was some obvious details that were missing in the proposals such as streamlining the interface between the XB-70 and the rocket. Aerodynamics is extremely important at mach 3 speeds.

The XB-70 is designed to sustain mach 3 over a long distance. The XB-70 satellite launcher only needs to fly a short distance but as high and fast as possible. Injecting a cryogenic liquid into the engine would be the easiest way to give a significant short term speed boost. With the mig-25 for instance it is well know the engines could overheat and destroy themselves during high speed runs. Liquid injection of various liquids has been studied during the 1960's and 1970's. Liquid O2 is probably the most likely candidate as it has commonality with the Rocket. The bomb bay of the XB-70 would have been the most likely location for the tank.

Here is a recent NASA study from 1993:

Analysis of gas turbine engines using water and oxygen injection to achieve high Mach numbers and high thrust

Analysis of gas turbine engines using water and oxygen injection to achieve high Mach numbers and high thrust - NASA Technical Reports Server (NTRS)

An analysis of gas turbine engines using water and oxygen injection to enhance performance by increasing Mach number capability and by increasing thrust is described. The liquids are injected, either separately or together, into the subsonic diffuser ahead of the engine compressor. A turbojet...

ntrs.nasa.gov

If an XB-70 aircraft dedicated to satellite launches was still in use today it would compliment the heavy lift launch vehicles in development. The 30-40 ton spaceplace with high delta-V would be the ultimate vehicle to allow passengers to LEO.

I think a cleansheet runway capable two stage to orbit reusable system would be an extremely smart development to start today. It is a solution that would compliment Starship and New Glenn. It is inevitable that we will have an extremely large space station in 10-20 years time. With today's technology an XB-70 sized aircraft without using scramjets could easily exceed mach 4.

 

[Archibald]

A Look Back… NAA B-70 Valkyrie Variants – A Future That Never Was…

Like flying cars, human colonies on Mars and so many other futuristic ideas, the 1950’s vision of the tomorrow was filled with grand ideas that are just now coming to fruition.

www.afmc.af.mil

A Look Back…Recoverable Rocket Boosters--A Future That Never Was

The idea of making flight into space as routine as atmospheric flight has been around since the 1930’s when Eugen Sänger first published detailed information about his ideas for a suborbital, winged

www.afmc.af.mil

The XB-70 could have dropped a 90 tons two-stage rocket at Mach 3. With low-energy props, that rocket could have delivered 8 metric tons to orbit.
My favorite combo: XB-70 + Minuteman + Agena.

Using high-energy props (LOX-LH2) payload would have been more than 10 metric tons.

View: https://www.youtube.com/watch?v=9gmeONd2VZo

I did some calculations about that huge belly fairing. Dimensions would have been 8 ft deep by 80 ft long by 30 ft wide. Enough to pack a huge rocket inside.

 

[RJMAZ]

That video is actually pretty embarrassing. The belly fairing blocks the landing gear and completely stuffs up the drag area ruling.

The wing mounted space plane would not allow the XB-70 to go supersonic due to asymmetric drag. There would be no advantage using the XB-70 compared to say a B-52.

The back mounted space plane it would need to be mounted conformally if they want to launch above Mach 3. The SR-71 had a back mounted drone called the D-21. As it wasn't conformally mounted the top speed of the SR-71 was halved.

The rear dorsal fuel tanks would probably need to be removed to allow a long rocket to fit conformally.