8 ms·

Some say this is an "inevitable" result of pushing boundaries. No. This is the result of a poorly managed program. What they are doing is much easier than th

by marze 12y ago

Some say this is an "inevitable" result of pushing boundaries. No. This is the result of a poorly managed program. What they are doing is much easier than the Apollo program, which was well managed and had no in-flight failures that resulted in loss of life, while accomplishing an infinitely harder task. This is a tragedy, obviously. But the program is about six years behind schedule, been going for 10 years. The most stupid thing they've done is stay with an experimental rubber/nitrous hybrid engine this whole time, instead of switching to liquid/liquid engine, a well proven technology. I know first hand that groups with such engine expertise have approached Virgin and been turned down. Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode. The pilots should have refused to fly until Virgin had 10 consecutive motor qualification tests at full duration, not ride on a ship with a half-baked motor that has seen constant modifications during the last year. In the software development world, a "death march" in a program behind schedule does not result in loss of actual life, not so in manned spaceflight.

DanBC 12y ago
> Apollo program, which was well managed and had no in-flight failures that resulted in loss of life The flaws in Apollo One were so severe the three crew died on the launchpad. Describing that tragedy as "no in-flight deaths" is accurate but misses some important information. http://en.wikipedia.org/wiki/Apollo_1 http://en.wikipedia.org/wiki/Apollo_1
- tdicola 12y ago
  Not to mention there were certainly other problems with Apollo like mission 13, or 11 barely landing before running out of fuel (computer problem forced Armstrong to take manual control and find a new landing spot at the last minute). Ultimately though Apollo was just too big and expensive a program to maintain, for better or worse.
  - cstross 12y ago
    ... Also, there was Neil Armstrong's ejection from the Lunar Landing Research Vehicle in 1966: http://en.wikipedia.org/wiki/Lunar_Landing_Research_Vehicle http://en.wikipedia.org/wiki/Lunar_Landing_Research_Vehicle (And I see another test pilot, Joe Algranti, also had a very close call flying a second-generation LLTV -- ejecting 0.6 seconds before it crashed!) NASA came very close to losing more astronauts during mission prep for Apollo, in addition to the Apollo 1 crew. (Even if we leave aside the four astronauts killed in T-38 crashes in the 1960s.)
  - Luc 12y ago
    > computer problem forced Armstrong to take manual control and find a new landing spot at the last minute The computer kept flying the machine despite the interrupts and reboots due to the radar switch that Buzz had left on. It was really marvelously designed to be able to keep on executing its highest priority tasks. The reason for the (semi) manual control was that the designated landing spot was a boulder field. The computer kept on operating the throttle. Source: Apollo 11 Lunar Surface Journal.
  - wozniacki 12y ago
    For what its worth - and not necessarily to draw parallels with the Cygnus CRS Orb-3 mishap - Russia successfully launched an unmanned Soyuz rocket and Progress 57 cargo ship with supplies for the International Space Station from the Baikonur Cosmodrome in Kazakhstan on Wednesday, hours after the catastrophic explosion destroyed a similar mission in the United States.[1] The cargo ship was expected to and successfully docked with the ISS later in the day.[2] [1] Russia Launches ISS Cargo After US Craft Explodes http://www.voanews.com/content/russia-launches-iss-cargo-mission-after-us-rocket-explodes/2500270.html http://www.voanews.com/content/russia-launches-iss-cargo-mis... Russian supply ship poised for launch Wednesday http://spaceflightnow.com/2014/10/28/russian-supply-ship-poised-for-launch-wednesday/ http://spaceflightnow.com/2014/10/28/russian-supply-ship-poi... [2] Russian Progress M-25M docks with the ISS http://www.nasaspaceflight.com/2014/10/russian-progress-iss-via-soyuz-2-1a-rocket/ http://www.nasaspaceflight.com/2014/10/russian-progress-iss-...
  - codewritinfool 12y ago
    Not exactly. The computer worked as designed. If they hadn't left the docking radar on, it would not have had any 1201 or 1202 alarms. A bunch of big rocks is why Armstrong took over.
- scott_s 12y ago
  Yes, and to bolster your point, they halted the program to re-evaluate safety. I think it's a human fault that we have to learn from our mistakes - unless we make them, people just don't believe the risks are real.
- marze 12y ago
  True. But it is almost pointless to compare these two programs since Apollo was so much more complex. To put it in perspective, Apollo flew on a rocket with five engines producing 1,500,000 lbf thrust each, on the first stage alone. By contrast, the Virgin motor produces 60,000 lbf thrust for 70 seconds. The Apollo program had a safety culture configured so that if anyone identified a safety issue, they became responsible for the problem and responsible to sign off that it was corrected.
  - vacri 12y ago
    Speaking of perspective, the Apollo was fully-backed by the government of the most powerful economy in the world at the time - 4% of the federal budget was directed towards it, with 34,000 NASA employees and 375,000 third-party employees, with a cost of ~$140B of today's dollars. How the hell is a private company supposed to compete? Not even Apple's famed $100B in cash could pay that bill. http://en.wikipedia.org/wiki/Budget_of_NASA#Cost_of_Apollo_program http://en.wikipedia.org/wiki/Budget_of_NASA#Cost_of_Apollo_p... Edit: It's also worth noting that the same entity that ran the Apollo missions currently has no way of putting people into space, and the last system they had also looked like a plane... and had problems with exploding and killing people.
    - marze 12y ago
      Another difference, the Apollo astronauts carried slide rules to do calculations during the mission.
      - exDM69 12y ago
        They had slide rules in addition to the most sophisticated digital computers of the time. Both, in the spacecraft and on the ground.
  - aptwebapps 12y ago
    "True. But it is almost pointless to compare these two programs since Apollo was so much more complex." That's funny, because you were the one who compared them first.
seanflyon 12y ago
> Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode. Does this same concern apply to plastic-based fuel? It does seem like a terrible idea to have people in the rocket the first time you try a new fuel mixture. "During the nine months since the previous rocket-powered test in January, Virgin Galactic switched SpaceShipTwo's fuel mixture from a rubber-based compound to a plastic-based mix — in hopes that the new formulation would boost the hybrid rocket engine's performance."
- termain 12y ago
  They tested the polyamide/nitrous engine back in May, I believe.
- deleted 12y ago
  [deleted]
- Florin_Andrei 12y ago
  A hybrid has a few other failure modes too. One is called hard start: http://en.wikipedia.org/wiki/Hard_start http://en.wikipedia.org/wiki/Hard_start Another - nitrous oxide can become explosive in gaseous phase. If enough of it became gas, the oxidizer tank may have exploded. There are also inherent instabilities of hybrids - higher pressure accelerates the burn, which increases pressure, which... We'll know more after they finish the investigation.
  - TrevorJ 12y ago
    Based on eye witness accounts saying that the engine appeared to fire once more after a flameout, the hard start scenario may indeed be at play here.
sliverstorm 12y ago
Some say this is an "inevitable" result of pushing boundaries. No. This is the result of a poorly managed program. Some of the boundaries that are being pushed are how much oversight, how meticulous, etc you have to be. In other words, how well you have to manage the program, how tight a ship you keep. Keeping a tight ship raises costs, and isn't the big emphasis of all this privatized space travel on reducing costs?
- x0054 12y ago
  That's a really grate way to sell tickets: "We now know just how careless we can be to limit in flight explosions to just one per year!" You can't use the same attitude that's now common in software startups with space vehicles, or any vehicles for that matter. "Ship now and fix problems later" does not work with real world products, and to be honest, should be avoided in software as well.
  - sliverstorm 12y ago
    That's one of the big ways the private sector cuts costs! Where do you imagine the "fat" that the private sector trims (relative to gov't) comes from? The private sector isn't somehow just better at stuff. It has different motives and different priorities, and makes different compromises.
    - icebraining 12y ago
      That's one of the big ways the private sector cuts costs! Is it? Is there evidence that the private sector is consistently more accident prone that public entities when doing similar activities?
- venomsnake 12y ago
  Costs are fixed. It is up to the culture to choose whether to pay in blood or treasure.
  - deleted 12y ago
    [deleted]
kashkhan 12y ago
there's no need not in this day and age to have test pilots. If they use computers, they can debug the engine in flight conditions by running maybe ten times as many test flights. Delays of months between flights are dangerous. Until you have a 1000-10,000 flights to build up operational data and envelope, this is a death trap causing unnecessary deaths.
- fnordfnordfnord 12y ago
  >there's no need not in this day and age to have test pilots. Good point. What does the FAA say about unmanned rocket powered flight tests?
  - learc83 12y ago
    Not sure, but SpaceX has performed plenty of them.
    - termain 12y ago
      Not so much over the US, though.
      - krisoft 12y ago
        I would beg to differ. SpaceX certainly flown unmanned, rocket powered test flights both from McGregor[1], and Cape Canaveral[2]. Those were in the US last time I checked. 1:http://en.wikipedia.org/wiki/Grasshopper_(rocket)#Flight_tests http://en.wikipedia.org/wiki/Grasshopper_(rocket)#Flight_tes... 2: http://en.wikipedia.org/wiki/Falcon_9#Launch_history http://en.wikipedia.org/wiki/Falcon_9#Launch_history
  - spiritplumber 12y ago
    If a regulation is putting human lives at risks, the regulation has to go.
  - kashkhan 12y ago
    plenty of companies do them. Ask Elon Musk.
termain 12y ago
"The most stupid thing they've done is stay with an experimental rubber/nitrous hybrid engine this whole time, instead of switching to liquid/liquid engine, a well proven technology." 1. They didn't stay with rubber/nitrous. 2. Like the sort used on Antares? "Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode." But what you know is wrong, they weren't using rubber. I think a good case can be made that they didn't do enough ground testing, but your post mixing disdain and falsity doesn't advance that case.
- dandelany 12y ago
  Point 1 is a good one, point 2 is not. Yes, liquid engines like the sort used on Antares, Soyuz (most reliable rocket ever built), Falcon, Proton, Atlas, Shuttle, Delta, Ariane, Saturn, and nearly every other orbital launch platform ever. Liquid/liquid engines, by any measure, are orders of magnitude more stable and well proven than hybrid rocket engines.
  - deleted 12y ago
    [deleted]
  - termain 12y ago
    My point is that they still fail. Both liquid and solid boosters are a lot more mature than hybrids, no doubt. But I'm not so sure that either is fundamentally more reliable. And for hybrids to mature, somebody has to use them. "Liquid/liquid engines, by any measure, are orders of magnitude more stable." What do you mean by stable? A reason to go with hybrids, at least on paper, is that they are mechanically simple but throttlable, hopefully combining the simplicity of a solid booster with the ability to throttle and shutdown of a liquid. Of course, much of that also applies to blowdown liquid systems, and I personally find a blowdown methane/lox system particularly compelling. I figure Virgin wanted to avoid cryogens, though.
- marze 12y ago
  "1. They didn't stay with rubber/nitrous." This you believe so strongly because a news story stated it? Wait for the accident report. It will say "rubber".
anentropic 12y ago
well, I don't think it can have been the rubber because it says in the article: "During the nine months since the previous rocket-powered test in January, Virgin Galactic switched SpaceShipTwo's fuel mixture from a rubber-based compound to a plastic-based mix"
jacquesm 12y ago
> Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode. Let's hope they won't ask you to run the inevitable investigation then.
abandonliberty 12y ago
You are certainly very good at finding evidence to validate your prejudice.
prof_hobart 12y ago
>Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode. Can I ask how? What is in there that tells you that?
- marze 12y ago
  Sure: intuition, not anything in that paragraph besides the simple fact that the vehicle destroyed itself during rocket powered flight. You've got a hybrid motor, it's flown a number of times. You have a program that has been going for years but still hasn't got the motor design finalized due to unknown (to us) problems. Failure modes that could destroy the vehicle include things like pressurized oxidizer tank failure, burn-through of the nozzle, burn-through of the main combustion pressure vessel, blocking of the nozzle by unburned solid fuel chunks causing over-pressure failure, and the like. The last one seems most likely, since it's likelihood is modified by modifications to the fuel (which is what they are probably changing, as opposed to the nitrous system or structure or nozzle). Obviously no one knows for sure yet. I'd love to see civilian spaceflight become a reality, so this is an unfortunate setback. I hope Virgin will be able to take the time to get it right. I hope they will look back at this accident the same way the Apollo program viewed the Apollo 1 fire, as a much needed chance to fix a lot of potential issues that needed fixing that were thought to have contributed in a fundamental way to the lack of subsequent in-flight failures.
rbanffy 12y ago
The hybrid rocket they are using is simpler and cheaper than a liquid/liquid design would be. I agree that, for all we know, it was the catastrophic failure of a rocket engine that was not tested enough that killed a pilot and that they should have tested the engine for much longer than they appear to have. I imagine they switched to this design because it's supposed to be a better one.
TrevorJ 12y ago
Even under the best circumstances, space travel is risky business. It may well be that this program didn't do all it should have done to mitigate those risks, but both facts can be true it's not mutually exclusive.
chris_wot 12y ago
You seem to have some sort of inside knowledge none of the rest of us have? Seriously, to say that this is a poorly managed program is something you can't provide any concrete evidence of - there has been a tragedy, but you cannot say that it was poorly managed because you don't know. In fact, you don't even know that rubber in the hybrid engine blocked the nozzle. You can't know that - you aren't part of the investigating team. And they don't even know yet.
stefanix 12y ago
Software development fuckups can be just as fatal as manned space flight. Software is actually the cause of many space flight accidents. To think of software as some isolated system that does not affect peoples' lives is absurd. It's critical in many areas and can fail with fatalities. https://en.wikipedia.org/wiki/List_of_software_bugs https://en.wikipedia.org/wiki/List_of_software_bugs - radiation therapy machine kills 5 - clock drift in Patriot system caused 28 killed - Chinook helicopter killed 29 due to bug in engine control - Toyota's electronic throttle control system caused dozens of fatalities
JabavuAdams 12y ago
This is two fatal accidents, so far. There was widespread speculation in the space community over Scaled Composite's seemingly blasé attitude to Nitrous Oxide, after their cold-flow test fatalities.

by marze 12y ago

DanBC 12y ago

> Apollo program, which was well managed and had no in-flight failures that resulted in loss of life The flaws in Apollo One were so severe the three crew died on the launchpad. Describing that tragedy as "no in-flight deaths" is accurate but misses some important information. http://en.wikipedia.org/wiki/Apollo_1 http://en.wikipedia.org/wiki/Apollo_1

tdicola 12y ago
Not to mention there were certainly other problems with Apollo like mission 13, or 11 barely landing before running out of fuel (computer problem forced Armstrong to take manual control and find a new landing spot at the last minute). Ultimately though Apollo was just too big and expensive a program to maintain, for better or worse.
- cstross 12y ago
  ... Also, there was Neil Armstrong's ejection from the Lunar Landing Research Vehicle in 1966: http://en.wikipedia.org/wiki/Lunar_Landing_Research_Vehicle http://en.wikipedia.org/wiki/Lunar_Landing_Research_Vehicle (And I see another test pilot, Joe Algranti, also had a very close call flying a second-generation LLTV -- ejecting 0.6 seconds before it crashed!) NASA came very close to losing more astronauts during mission prep for Apollo, in addition to the Apollo 1 crew. (Even if we leave aside the four astronauts killed in T-38 crashes in the 1960s.)
- Luc 12y ago
  > computer problem forced Armstrong to take manual control and find a new landing spot at the last minute The computer kept flying the machine despite the interrupts and reboots due to the radar switch that Buzz had left on. It was really marvelously designed to be able to keep on executing its highest priority tasks. The reason for the (semi) manual control was that the designated landing spot was a boulder field. The computer kept on operating the throttle. Source: Apollo 11 Lunar Surface Journal.
- wozniacki 12y ago
  For what its worth - and not necessarily to draw parallels with the Cygnus CRS Orb-3 mishap - Russia successfully launched an unmanned Soyuz rocket and Progress 57 cargo ship with supplies for the International Space Station from the Baikonur Cosmodrome in Kazakhstan on Wednesday, hours after the catastrophic explosion destroyed a similar mission in the United States.[1] The cargo ship was expected to and successfully docked with the ISS later in the day.[2] [1] Russia Launches ISS Cargo After US Craft Explodes http://www.voanews.com/content/russia-launches-iss-cargo-mission-after-us-rocket-explodes/2500270.html http://www.voanews.com/content/russia-launches-iss-cargo-mis... Russian supply ship poised for launch Wednesday http://spaceflightnow.com/2014/10/28/russian-supply-ship-poised-for-launch-wednesday/ http://spaceflightnow.com/2014/10/28/russian-supply-ship-poi... [2] Russian Progress M-25M docks with the ISS http://www.nasaspaceflight.com/2014/10/russian-progress-iss-via-soyuz-2-1a-rocket/ http://www.nasaspaceflight.com/2014/10/russian-progress-iss-...
- codewritinfool 12y ago
  Not exactly. The computer worked as designed. If they hadn't left the docking radar on, it would not have had any 1201 or 1202 alarms. A bunch of big rocks is why Armstrong took over.
scott_s 12y ago
Yes, and to bolster your point, they halted the program to re-evaluate safety. I think it's a human fault that we have to learn from our mistakes - unless we make them, people just don't believe the risks are real.
marze 12y ago
True. But it is almost pointless to compare these two programs since Apollo was so much more complex. To put it in perspective, Apollo flew on a rocket with five engines producing 1,500,000 lbf thrust each, on the first stage alone. By contrast, the Virgin motor produces 60,000 lbf thrust for 70 seconds. The Apollo program had a safety culture configured so that if anyone identified a safety issue, they became responsible for the problem and responsible to sign off that it was corrected.
- vacri 12y ago
  Speaking of perspective, the Apollo was fully-backed by the government of the most powerful economy in the world at the time - 4% of the federal budget was directed towards it, with 34,000 NASA employees and 375,000 third-party employees, with a cost of ~$140B of today's dollars. How the hell is a private company supposed to compete? Not even Apple's famed $100B in cash could pay that bill. http://en.wikipedia.org/wiki/Budget_of_NASA#Cost_of_Apollo_program http://en.wikipedia.org/wiki/Budget_of_NASA#Cost_of_Apollo_p... Edit: It's also worth noting that the same entity that ran the Apollo missions currently has no way of putting people into space, and the last system they had also looked like a plane... and had problems with exploding and killing people.
  - marze 12y ago
    Another difference, the Apollo astronauts carried slide rules to do calculations during the mission.
    - exDM69 12y ago
      They had slide rules in addition to the most sophisticated digital computers of the time. Both, in the spacecraft and on the ground.
- aptwebapps 12y ago
  "True. But it is almost pointless to compare these two programs since Apollo was so much more complex." That's funny, because you were the one who compared them first.

seanflyon 12y ago

> Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode. Does this same concern apply to plastic-based fuel? It does seem like a terrible idea to have people in the rocket the first time you try a new fuel mixture. "During the nine months since the previous rocket-powered test in January, Virgin Galactic switched SpaceShipTwo's fuel mixture from a rubber-based compound to a plastic-based mix — in hopes that the new formulation would boost the hybrid rocket engine's performance."

termain 12y ago
They tested the polyamide/nitrous engine back in May, I believe.
deleted 12y ago
[deleted]
Florin_Andrei 12y ago
A hybrid has a few other failure modes too. One is called hard start: http://en.wikipedia.org/wiki/Hard_start http://en.wikipedia.org/wiki/Hard_start Another - nitrous oxide can become explosive in gaseous phase. If enough of it became gas, the oxidizer tank may have exploded. There are also inherent instabilities of hybrids - higher pressure accelerates the burn, which increases pressure, which... We'll know more after they finish the investigation.
- TrevorJ 12y ago
  Based on eye witness accounts saying that the engine appeared to fire once more after a flameout, the hard start scenario may indeed be at play here.

sliverstorm 12y ago

Some say this is an "inevitable" result of pushing boundaries. No. This is the result of a poorly managed program. Some of the boundaries that are being pushed are how much oversight, how meticulous, etc you have to be. In other words, how well you have to manage the program, how tight a ship you keep. Keeping a tight ship raises costs, and isn't the big emphasis of all this privatized space travel on reducing costs?

x0054 12y ago
That's a really grate way to sell tickets: "We now know just how careless we can be to limit in flight explosions to just one per year!" You can't use the same attitude that's now common in software startups with space vehicles, or any vehicles for that matter. "Ship now and fix problems later" does not work with real world products, and to be honest, should be avoided in software as well.
- sliverstorm 12y ago
  That's one of the big ways the private sector cuts costs! Where do you imagine the "fat" that the private sector trims (relative to gov't) comes from? The private sector isn't somehow just better at stuff. It has different motives and different priorities, and makes different compromises.
  - icebraining 12y ago
    That's one of the big ways the private sector cuts costs! Is it? Is there evidence that the private sector is consistently more accident prone that public entities when doing similar activities?
venomsnake 12y ago
Costs are fixed. It is up to the culture to choose whether to pay in blood or treasure.
- deleted 12y ago
  [deleted]

kashkhan 12y ago

there's no need not in this day and age to have test pilots. If they use computers, they can debug the engine in flight conditions by running maybe ten times as many test flights. Delays of months between flights are dangerous. Until you have a 1000-10,000 flights to build up operational data and envelope, this is a death trap causing unnecessary deaths.

fnordfnordfnord 12y ago
>there's no need not in this day and age to have test pilots. Good point. What does the FAA say about unmanned rocket powered flight tests?
- learc83 12y ago
  Not sure, but SpaceX has performed plenty of them.
  - termain 12y ago
    Not so much over the US, though.
    - krisoft 12y ago
      I would beg to differ. SpaceX certainly flown unmanned, rocket powered test flights both from McGregor[1], and Cape Canaveral[2]. Those were in the US last time I checked. 1:http://en.wikipedia.org/wiki/Grasshopper_(rocket)#Flight_tests http://en.wikipedia.org/wiki/Grasshopper_(rocket)#Flight_tes... 2: http://en.wikipedia.org/wiki/Falcon_9#Launch_history http://en.wikipedia.org/wiki/Falcon_9#Launch_history
- spiritplumber 12y ago
  If a regulation is putting human lives at risks, the regulation has to go.
- kashkhan 12y ago
  plenty of companies do them. Ask Elon Musk.

termain 12y ago

"The most stupid thing they've done is stay with an experimental rubber/nitrous hybrid engine this whole time, instead of switching to liquid/liquid engine, a well proven technology." 1. They didn't stay with rubber/nitrous. 2. Like the sort used on Antares? "Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode." But what you know is wrong, they weren't using rubber. I think a good case can be made that they didn't do enough ground testing, but your post mixing disdain and falsity doesn't advance that case.

dandelany 12y ago
Point 1 is a good one, point 2 is not. Yes, liquid engines like the sort used on Antares, Soyuz (most reliable rocket ever built), Falcon, Proton, Atlas, Shuttle, Delta, Ariane, Saturn, and nearly every other orbital launch platform ever. Liquid/liquid engines, by any measure, are orders of magnitude more stable and well proven than hybrid rocket engines.
- deleted 12y ago
  [deleted]
- termain 12y ago
  My point is that they still fail. Both liquid and solid boosters are a lot more mature than hybrids, no doubt. But I'm not so sure that either is fundamentally more reliable. And for hybrids to mature, somebody has to use them. "Liquid/liquid engines, by any measure, are orders of magnitude more stable." What do you mean by stable? A reason to go with hybrids, at least on paper, is that they are mechanically simple but throttlable, hopefully combining the simplicity of a solid booster with the ability to throttle and shutdown of a liquid. Of course, much of that also applies to blowdown liquid systems, and I personally find a blowdown methane/lox system particularly compelling. I figure Virgin wanted to avoid cryogens, though.
marze 12y ago
"1. They didn't stay with rubber/nitrous." This you believe so strongly because a news story stated it? Wait for the accident report. It will say "rubber".

anentropic 12y ago

well, I don't think it can have been the rubber because it says in the article: "During the nine months since the previous rocket-powered test in January, Virgin Galactic switched SpaceShipTwo's fuel mixture from a rubber-based compound to a plastic-based mix"

jacquesm 12y ago

> Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode. Let's hope they won't ask you to run the inevitable investigation then.

abandonliberty 12y ago

You are certainly very good at finding evidence to validate your prejudice.

prof_hobart 12y ago

>Seeing only the first paragraph, I already know that some rubber in the hybrid engine detached blocking the nozzle and causing the whole engine to explode. Can I ask how? What is in there that tells you that?

marze 12y ago
Sure: intuition, not anything in that paragraph besides the simple fact that the vehicle destroyed itself during rocket powered flight. You've got a hybrid motor, it's flown a number of times. You have a program that has been going for years but still hasn't got the motor design finalized due to unknown (to us) problems. Failure modes that could destroy the vehicle include things like pressurized oxidizer tank failure, burn-through of the nozzle, burn-through of the main combustion pressure vessel, blocking of the nozzle by unburned solid fuel chunks causing over-pressure failure, and the like. The last one seems most likely, since it's likelihood is modified by modifications to the fuel (which is what they are probably changing, as opposed to the nitrous system or structure or nozzle). Obviously no one knows for sure yet. I'd love to see civilian spaceflight become a reality, so this is an unfortunate setback. I hope Virgin will be able to take the time to get it right. I hope they will look back at this accident the same way the Apollo program viewed the Apollo 1 fire, as a much needed chance to fix a lot of potential issues that needed fixing that were thought to have contributed in a fundamental way to the lack of subsequent in-flight failures.

rbanffy 12y ago

The hybrid rocket they are using is simpler and cheaper than a liquid/liquid design would be. I agree that, for all we know, it was the catastrophic failure of a rocket engine that was not tested enough that killed a pilot and that they should have tested the engine for much longer than they appear to have. I imagine they switched to this design because it's supposed to be a better one.

TrevorJ 12y ago

Even under the best circumstances, space travel is risky business. It may well be that this program didn't do all it should have done to mitigate those risks, but both facts can be true it's not mutually exclusive.

chris_wot 12y ago

You seem to have some sort of inside knowledge none of the rest of us have? Seriously, to say that this is a poorly managed program is something you can't provide any concrete evidence of - there has been a tragedy, but you cannot say that it was poorly managed because you don't know. In fact, you don't even know that rubber in the hybrid engine blocked the nozzle. You can't know that - you aren't part of the investigating team. And they don't even know yet.

stefanix 12y ago

Software development fuckups can be just as fatal as manned space flight. Software is actually the cause of many space flight accidents. To think of software as some isolated system that does not affect peoples' lives is absurd. It's critical in many areas and can fail with fatalities. https://en.wikipedia.org/wiki/List_of_software_bugs https://en.wikipedia.org/wiki/List_of_software_bugs - radiation therapy machine kills 5 - clock drift in Patriot system caused 28 killed - Chinook helicopter killed 29 due to bug in engine control - Toyota's electronic throttle control system caused dozens of fatalities

JabavuAdams 12y ago

This is two fatal accidents, so far. There was widespread speculation in the space community over Scaled Composite's seemingly blasé attitude to Nitrous Oxide, after their cold-flow test fatalities.