Branson admits Virgin space mission was going the wrong direction(thememo.com)
thememo.com
Branson admits Virgin space mission was going the wrong direction
http://www.thememo.com/2017/03/03/branson-quietly-admits-20-year-space-mission-was-going-the-wrong-way/
23 comments
> 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.
Rutan won the X-Prize, I don't believe you can call that wrong. This was always space tourism, nothing more.
"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.
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.
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.
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.
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.
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 ), i can't begin to imagine the bigger problems to get higher.
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?
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.
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.
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!
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!
> 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.
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.
I must say - both physically compelled by the pun and because that it is a pun makes it no less true - that SpaceX has been a rousing success for the "launch and iterate" mantra so often pushed on HN. Having a product, that works, that people can pay you for, as soon as possible makes a huge difference, even if what you push out first is no where near what you want your finished product to be. The contrast to Virgin Galactic is startling.
SpaceX looks like a software company that has had success with their product so far but is in the process of a major refactoring to a new technology base.
Basically if they want to fly reusable rockets with high reliability and low refurbishment time and cost, they have to redesign and rebuild quite a lot. And they need new philosophies and processes.
You can for example look at their current Merlin gas generator technology engines. The chosen cycle results in high temperatures for the turbine, something which works against reliability and reusability. They have the staged combustion Raptor engine coming up, but they are too big to be used as landing engines, so they have to do that in another way.
Gas generator as a first engine (and pressure fed upper stage) makes a lot of sense though.
On the other hand, Virgin Galactic chose an unconventional and hard to scale technology: hybrid rockets, which has proved even more problematic.
As a fairly technical person, you look at these companies and organizations (NASA) and feel how they just simply can't make technically informed decisions higher up. SpaceX has improved a lot historically though.
Do you know if there are companies with technical leadership?
Basically if they want to fly reusable rockets with high reliability and low refurbishment time and cost, they have to redesign and rebuild quite a lot. And they need new philosophies and processes.
You can for example look at their current Merlin gas generator technology engines. The chosen cycle results in high temperatures for the turbine, something which works against reliability and reusability. They have the staged combustion Raptor engine coming up, but they are too big to be used as landing engines, so they have to do that in another way.
Gas generator as a first engine (and pressure fed upper stage) makes a lot of sense though.
On the other hand, Virgin Galactic chose an unconventional and hard to scale technology: hybrid rockets, which has proved even more problematic.
As a fairly technical person, you look at these companies and organizations (NASA) and feel how they just simply can't make technically informed decisions higher up. SpaceX has improved a lot historically though.
Do you know if there are companies with technical leadership?
Projects are never going to pick the perfect solution out of the gate. But, tested compromises also have value.
I would suggest SpaceX freeze a design every 5-7 years that's good enough to scale while cheaper than it's completion and then have a more experimental path. If option A costs 20 million more, but has a 98+% success rate and option B saves 20 million then the market can chose which to focus on.
The real 'problem' spaceX is facing is humans simply don't send all that much stuff into space, so they are never get enough data get the experimental path stable.
I would suggest SpaceX freeze a design every 5-7 years that's good enough to scale while cheaper than it's completion and then have a more experimental path. If option A costs 20 million more, but has a 98+% success rate and option B saves 20 million then the market can chose which to focus on.
The real 'problem' spaceX is facing is humans simply don't send all that much stuff into space, so they are never get enough data get the experimental path stable.
A sensible shift, but comes a bit late. The success india, spacex, ula, are having will lead to kepler syndrome before he gets operational if I had to bet on it. Still, I support every dollar spent on space tech. I only hope the tech developed for dead end projects is released if unused.
>Kepler syndrome
Do you mean Kessler Syndrome? https://en.wikipedia.org/wiki/Kessler_syndrome
Do you mean Kessler Syndrome? https://en.wikipedia.org/wiki/Kessler_syndrome
I like "Kepler Syndrome".
The runaway proliferation of humans on nearby habitable planets.
The runaway proliferation of humans on nearby habitable planets.
Too early for space tourism.
Musk announced couple of days ago a plan to send tourists on a sightseeing trip around Moon. And not as some hypothetical plan, but in a sense that the said tourists have bought the tickets.
Now, with their track record it looks like it's probably going to take 2x more time than the announced schedule says, but on the other hand, 2x is quite much sooner than 'never'.
Now, with their track record it looks like it's probably going to take 2x more time than the announced schedule says, but on the other hand, 2x is quite much sooner than 'never'.
There have already been tourist flights to space (eg ISS), plus Virgin already has deposits on suborbital flights. So I would argue the door is open and there's money to be made.
Perhaps the winged approach is not optimal for orbital missions, like to the Virgin hotel, but I can't see why they would turn down scores of paying suborbital trips, for which wings probably make a lot more sense. They might as well keep up the SS2 path to finance the higher goals.
Perhaps the winged approach is not optimal for orbital missions, like to the Virgin hotel, but I can't see why they would turn down scores of paying suborbital trips, for which wings probably make a lot more sense. They might as well keep up the SS2 path to finance the higher goals.
yes, diagonal not vertical how it should be.
down?
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)
They at least understand the mass trade-offs being made and are trying to develop new technology that helps skirt around them.