SSTO is kind of the holy grail. It looks to me that the rocket sled for takeoff is an effort to keep some of the propulsive hardware and propellant on the ground to save weight. Clearly, that reduces flexibility in terms of where you can take off from. I would love to see them transition to a more traditional horizontal, if long runway without the sled and have a very flexible spaceplane. This is where Virgin Galactic has an advantage.
Space isn't orbit. It takes barely a few percent of energy to get to sapce compared to orbit. Orbital launches from plane don't work because they add very little to the orbital velocity, which is all that actually matters, not the altitude. On top of that they put huge limitations on the size of actual spaceship.
Let's try the math a bit ... So around 9 km/s to reach orbit and let's they can get to Mach 3 with their rocket slade or around 1 km/s --- so let's assume a phenomenal specific impulse of 350 s or around 3.5 km/s exhaust velocity --- so 8/3.5 ~2.2857 and that means e^2.2857 or around 6.2 more fuel than dry mass --- however when it's mere 300s it's far more than ten or around 14 something --- so I assume they manage air braking with phenomal good materials and not that ceramic crap the space shuttle used and spacex is using and they need little fuel for the landing ((already a challenge too tough but anyway)) --- however when they nearly reach orbital velocity and let the kick stage do the rest --- let's assume the kick stage gives a deltaV of 1.5 for deploying the satellite --- we end up just with 6.5 km/s for that "SSTO" to reach and the company gets paid and returns that fancy aircraft ---- 6.5 km/s deltaV means just about 8.7 more fuel than dry mass and that with just an average specific impulse of 300s --- so after thinking of it a bit for an hour I came up with the conclusion that the kickstage will make it work ---- and for the future that the kickstage becomes smaller until it's not required at all
We're talking about a large vehicle with a wet mass of let's say 5000 tons. Is the sled going to hit Mach 3? No it's not it's going to hit about maybe 500 to 600kph, enough for the wings to lift the enormous mass. Considering drag from the massive airframe that's barely enough to gain 2km of altitude. It's not nothing, but it's not enough, and I don't think this works without detachable boosters or some crazy powerful air breathing engines. I'd kill to see their rocket equation because I'd bet cash money they haven't solved it yet.
@@StoneUSA Why are you so pessimistic about rocket sleds? Drag per m² is usually less for larger objects because volume increases faster than surface area.
Great interview and some great concepts.
SSTO? Would love to see it happen. It'll be a great achievement.
Somebody read those NASA papers on the ultimate dark art of rocketry
The dry mass fraction required for that is going to be utterly unforgiving.
SSTO is kind of the holy grail. It looks to me that the rocket sled for takeoff is an effort to keep some of the propulsive hardware and propellant on the ground to save weight. Clearly, that reduces flexibility in terms of where you can take off from. I would love to see them transition to a more traditional horizontal, if long runway without the sled and have a very flexible spaceplane. This is where Virgin Galactic has an advantage.
Space isn't orbit. It takes barely a few percent of energy to get to sapce compared to orbit. Orbital launches from plane don't work because they add very little to the orbital velocity, which is all that actually matters, not the altitude. On top of that they put huge limitations on the size of actual spaceship.
Was there an estimated cost per kg to LEO? Or did I just miss it?
Let's try the math a bit ... So around 9 km/s to reach orbit and let's they can get to Mach 3 with their rocket slade or around 1 km/s --- so let's assume a phenomenal specific impulse of 350 s or around 3.5 km/s exhaust velocity --- so 8/3.5 ~2.2857 and that means e^2.2857 or around 6.2 more fuel than dry mass --- however when it's mere 300s it's far more than ten or around 14 something --- so I assume they manage air braking with phenomal good materials and not that ceramic crap the space shuttle used and spacex is using and they need little fuel for the landing ((already a challenge too tough but anyway)) --- however when they nearly reach orbital velocity and let the kick stage do the rest --- let's assume the kick stage gives a deltaV of 1.5 for deploying the satellite --- we end up just with 6.5 km/s for that "SSTO" to reach and the company gets paid and returns that fancy aircraft ---- 6.5 km/s deltaV means just about 8.7 more fuel than dry mass and that with just an average specific impulse of 300s --- so after thinking of it a bit for an hour I came up with the conclusion that the kickstage will make it work ---- and for the future that the kickstage becomes smaller until it's not required at all
We're talking about a large vehicle with a wet mass of let's say 5000 tons. Is the sled going to hit Mach 3? No it's not it's going to hit about maybe 500 to 600kph, enough for the wings to lift the enormous mass. Considering drag from the massive airframe that's barely enough to gain 2km of altitude. It's not nothing, but it's not enough, and I don't think this works without detachable boosters or some crazy powerful air breathing engines. I'd kill to see their rocket equation because I'd bet cash money they haven't solved it yet.
@@StoneUSA Why are you so pessimistic about rocket sleds? Drag per m² is usually less for larger objects because volume increases faster than surface area.
Think round wide and reusable propellent.
The spaceship in the 1951 George Pal sci-fi classic "When Worlds Collide" launched the same way. ua-cam.com/video/avtQ8elxL-o/v-deo.html
So it's not exactly an SSTO due to the use of the sled. Cool, nevertheless 🤔
18:41 Don't be shy and admit it's a Third Reich idea!
lol, I suppose you could say that about turbopumps too