3 ms·

There's no indication that they've figured out that Virgin's real problem is their architecture. They're still trying to use wings to get to space. The Germans

There's no indication that they've figured out that Virgin's real problem is their architecture. They're still trying to use wings to get to space. The Germans and NASA back in the 50s understood that "mass is mass", and wings compete with fuel for weight. They're dead mass you have to accelerate. The lift they provide isn't worth it. The Russians put Sputnik and Gegarin in orbit with a rocket. NASA went to the Moon with a rocket. ICBMs are rockets. SpaceX and Blue Origin are making rockets. Branson's problem is that he founded a company started by Burt Rutan (a brilliant airplane designer), and never hired the right rocket designers, and he doesn't have the technical expertise himself to realize what he's doing wrong. For an example of a rocket company that understands this, but is trying to square the circle anyway, read about Skylon. https://en.wikipedia.org/wiki/Skylon_(spacecraft) https://en.wikipedia.org/wiki/Skylon_(spacecraft) They at least understand the mass trade-offs being made and are trying to develop new technology that helps skirt around them.

ProAm 10y ago
> Branson's problem is that he founded a company started by Burt Rutan (a brilliant airplane designer), and never hired the right rocket designers, and he doesn't have the technical expertise himself to realize what he's doing wrong. Rutan won the X-Prize, I don't believe you can call that wrong. This was always space tourism, nothing more.
- bmcusick 10y ago
  "Rutan won the X-Prize" Yes, he did, but he did with an architecture incapable of doing anything more impressive than win the X-Prize. I'll give you another example from the self-driving X-prize. There were always two teams that were very close to winning. One team hand-coded every decision tree for the particular path the car might encounter, and the other team used machine learning and let the car figure it. Now as it happened in the self-driving challenge, the machine-learning car won, but it was really, really close. For the limited purpose of the challenge, the hand-coded car was nearly good enough. Maybe if they'd hand-coded it just a little better, that car would have won. But hand-coding doesn't scale from a closed challenge track to real-world self-driving cars. Only machine learning can do that. But because of the artificial constraints on the challenge, the non-scaling solution almost won. Well for the Ansari X-Prize, the non-scaling solution DID win. That's the Rutan solution, which used wings, which work for 1 passenger but (as Branson has spent 20 years and a billion dollars proving) doesn't even scale to 10 passenger joy-rides, let alone orbit.
- sbuttgereit 10y ago
  And suborbital space tourism at that. I think the article largely got the situation correct. It would also be interesting to see what capital both teams were working with... for SpaceX at least up to the first contracted launch.
rz2k 10y ago
Would you say that achieving orbit is a problem of achieving velocity more than lifting to a certain altitude, and that wings are a delicate tool for decelerating when coming back to earth?
- bmcusick 10y ago
  Yes, absolutely. That's why the Apollo capsules and the Dragon spacecraft don't have them. The loads and heat involved are enormous. Even the Space Shuttle had pretty stubby wings, and the special tiles those wings needed to protect themselves were a constant source of high-cost maintenance (and ended up destroying one of the Shuttles and killing all its crew when they failed). The wings on SpaceShipOne were pretty light and flimsy because they didn't need to be any stronger considering how slow SpaceShipOne's top speed was. It topped out at Mach 3, and you need to reach Mach 25 to achieve orbit. Wings strong enough to handle Mach 25 would be too heavy to ever reach Mach 25; Catch 22!
- pdonis 10y ago
  > achieving orbit is a problem of achieving velocity more than lifting to a certain altitude Yes, and this has been well understood for decades. The basic math is simple: per unit mass, the potential energy change required to get from the Earth's surface to orbital altitude (say 200 km, or 200,000 meters) is gh = 9.8 * 200,000 = about 2 million Joules/kg whereas the kinetic energy change required to get from rest on the rotating Earth, a speed of about 300 m/s at the latitude of the Kennedy Space Center, to orbital speed, 8000 m/s, is 1/2 (v2^2 - v1^2) = 1/2 (8000^2 - 300^2) = about 32 million Joules/kg So the change in velocity dominates the energy requirement, which drives everything else.
- taylorexpander 10y ago
  There is actually a term used in the field by engineers and scientists: "delta v." You might have heard Musk mention it a few times in his talks. It's a measure of change in velocity (hence the delta… v…, and in mathematical terms is literally written with the symbol delta) required to reach or escape x orbit. For example you need a delta v of approx 9.3 km/s to go from Earth to LEO. From LEO to GEO you'd need a delta v of roughly half of that. Engineers in this sense would talk about a total delta v budget of ~13 km/s and some change to achieve Earth to GEO. The question is then how do you design a rocket that can produce those numbers? Higher delta v requirements means higher mass requirements. You'd need more propellant to produce that thrust, and more structure to house it and hardware to control it. At some point it simply doesn't work anymore because it becomes counter intuitive to keep adding more mass. Enter the concept of staging. Staging allows you to discard your useless mass after it's done it's job. For example you might need 9.3 km/s to achieve LEO, but you might also know it's not a linear relationship so that you need more of that upfront and less of it later. In that case, rocket engineers simply designed around that and created heavy first lift stages to produce the bulk of that delta v, and then discarding the heavy structure and hardware after the propellant has been exhausted.
7b64f0f2 10y ago
I was about to comment on what skunk works did with the U2 and the SR71, but then i saw that virgin wanted to go at 4x the service ceiling of these two planes. These two planes already had several very hard problems to solve (as related in https://www.goodreads.com/book/show/101438.Skunk_Works https://www.goodreads.com/book/show/101438.Skunk_Works ), i can't begin to imagine the bigger problems to get higher.
nkoren 10y ago
This is true. All the space engineers I knew were saying, at the time, that scaling wings is a hell of a lot harder than scaling rockets. And it has been. Plus, air-launch introduces an extra element of operational complexity, and extra manufacturing complexity since you have two lines of hardware with very few synergies between them. These problems could have been overcome, however. They would be left with a more complicated and expensive space-tourism system than is strictly necessary, but there's no reason it can't be done. Overcoming the limitations of their architecture, however, would have required good management. They haven't had that: a quick perusal of glassdoor shows that their management is driven by people whose core competency is back-scratching and accruing seniority, rather than a meritocracy driven by technical and managerial skill. That problem, alone, has been more than sufficient to keep Virgin Galactic grounded. Bad management can kill even the most elegant, viable technology.

ProAm 10y ago

> Branson's problem is that he founded a company started by Burt Rutan (a brilliant airplane designer), and never hired the right rocket designers, and he doesn't have the technical expertise himself to realize what he's doing wrong. Rutan won the X-Prize, I don't believe you can call that wrong. This was always space tourism, nothing more.

bmcusick 10y ago
"Rutan won the X-Prize" Yes, he did, but he did with an architecture incapable of doing anything more impressive than win the X-Prize. I'll give you another example from the self-driving X-prize. There were always two teams that were very close to winning. One team hand-coded every decision tree for the particular path the car might encounter, and the other team used machine learning and let the car figure it. Now as it happened in the self-driving challenge, the machine-learning car won, but it was really, really close. For the limited purpose of the challenge, the hand-coded car was nearly good enough. Maybe if they'd hand-coded it just a little better, that car would have won. But hand-coding doesn't scale from a closed challenge track to real-world self-driving cars. Only machine learning can do that. But because of the artificial constraints on the challenge, the non-scaling solution almost won. Well for the Ansari X-Prize, the non-scaling solution DID win. That's the Rutan solution, which used wings, which work for 1 passenger but (as Branson has spent 20 years and a billion dollars proving) doesn't even scale to 10 passenger joy-rides, let alone orbit.
sbuttgereit 10y ago
And suborbital space tourism at that. I think the article largely got the situation correct. It would also be interesting to see what capital both teams were working with... for SpaceX at least up to the first contracted launch.

rz2k 10y ago

Would you say that achieving orbit is a problem of achieving velocity more than lifting to a certain altitude, and that wings are a delicate tool for decelerating when coming back to earth?

bmcusick 10y ago
Yes, absolutely. That's why the Apollo capsules and the Dragon spacecraft don't have them. The loads and heat involved are enormous. Even the Space Shuttle had pretty stubby wings, and the special tiles those wings needed to protect themselves were a constant source of high-cost maintenance (and ended up destroying one of the Shuttles and killing all its crew when they failed). The wings on SpaceShipOne were pretty light and flimsy because they didn't need to be any stronger considering how slow SpaceShipOne's top speed was. It topped out at Mach 3, and you need to reach Mach 25 to achieve orbit. Wings strong enough to handle Mach 25 would be too heavy to ever reach Mach 25; Catch 22!
pdonis 10y ago
> achieving orbit is a problem of achieving velocity more than lifting to a certain altitude Yes, and this has been well understood for decades. The basic math is simple: per unit mass, the potential energy change required to get from the Earth's surface to orbital altitude (say 200 km, or 200,000 meters) is gh = 9.8 * 200,000 = about 2 million Joules/kg whereas the kinetic energy change required to get from rest on the rotating Earth, a speed of about 300 m/s at the latitude of the Kennedy Space Center, to orbital speed, 8000 m/s, is 1/2 (v2^2 - v1^2) = 1/2 (8000^2 - 300^2) = about 32 million Joules/kg So the change in velocity dominates the energy requirement, which drives everything else.
taylorexpander 10y ago
There is actually a term used in the field by engineers and scientists: "delta v." You might have heard Musk mention it a few times in his talks. It's a measure of change in velocity (hence the delta… v…, and in mathematical terms is literally written with the symbol delta) required to reach or escape x orbit. For example you need a delta v of approx 9.3 km/s to go from Earth to LEO. From LEO to GEO you'd need a delta v of roughly half of that. Engineers in this sense would talk about a total delta v budget of ~13 km/s and some change to achieve Earth to GEO. The question is then how do you design a rocket that can produce those numbers? Higher delta v requirements means higher mass requirements. You'd need more propellant to produce that thrust, and more structure to house it and hardware to control it. At some point it simply doesn't work anymore because it becomes counter intuitive to keep adding more mass. Enter the concept of staging. Staging allows you to discard your useless mass after it's done it's job. For example you might need 9.3 km/s to achieve LEO, but you might also know it's not a linear relationship so that you need more of that upfront and less of it later. In that case, rocket engineers simply designed around that and created heavy first lift stages to produce the bulk of that delta v, and then discarding the heavy structure and hardware after the propellant has been exhausted.

7b64f0f2 10y ago

I was about to comment on what skunk works did with the U2 and the SR71, but then i saw that virgin wanted to go at 4x the service ceiling of these two planes. These two planes already had several very hard problems to solve (as related in https://www.goodreads.com/book/show/101438.Skunk_Works https://www.goodreads.com/book/show/101438.Skunk_Works ), i can't begin to imagine the bigger problems to get higher.

nkoren 10y ago

This is true. All the space engineers I knew were saying, at the time, that scaling wings is a hell of a lot harder than scaling rockets. And it has been. Plus, air-launch introduces an extra element of operational complexity, and extra manufacturing complexity since you have two lines of hardware with very few synergies between them. These problems could have been overcome, however. They would be left with a more complicated and expensive space-tourism system than is strictly necessary, but there's no reason it can't be done. Overcoming the limitations of their architecture, however, would have required good management. They haven't had that: a quick perusal of glassdoor shows that their management is driven by people whose core competency is back-scratching and accruing seniority, rather than a meritocracy driven by technical and managerial skill. That problem, alone, has been more than sufficient to keep Virgin Galactic grounded. Bad management can kill even the most elegant, viable technology.