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#20
by
akula2
on 15 Dec, 2012 06:27
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I really don't know how many here are Engineers/Scientists. Briz-M is not unique just because it happens to be Soviet technology. Such things are quite common in other industries (west) too.
#1 Anyone remember how Air France 447 (Airbus A-330 happens to be most advanced in its design that time) vanished out of trace from Brazil?
#2 How about brand new Ferrari 458 Italia infamous hot fires (friend of mine lost one)
#3 Then there are Airbus A-380 engine problems (remember Qantas grounded them)
#4 If we go back to the US Air Force, anyone remembers how many SR-71s they lost (that too in non-combat accidents)?
Progress has impressive record but it's unfortunate that Briz-M problems are recurring, rather say becoming so predictable! IMO Mr. Putin should take charge of the Russian Space Agency.
Soviet technology still good enough, Soyuz/Progress proves this very much. In my experience, there is increased accuracy of GLONASS over GPS on some parameters.
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#21
by
Jim
on 15 Dec, 2012 13:47
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#1 Anyone remember how Air France 447 (Airbus A-330 happens to be most advanced in its design that time) vanished out of trace from Brazil?
#4 If we go back to the US Air Force, anyone remembers how many SR-71s they lost (that too in non-combat accidents)?
Pilot errors
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#22
by
akula2
on 15 Dec, 2012 16:51
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Pilot errors
Not all were/are pilot errors. There was a design deficiency in that illfated A-330 control system (side stick etc), complemented with a few complicated instruments/sensors (say Pitot Tube nightmare at high altitude).
Lockheed Martin knows very well dealing with numerous design errors/deficiencies in Systems/Software be it in F-22 or F-35
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#23
by
Stephan
on 15 Dec, 2012 17:13
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Not all were/are pilot errors. There was a design deficiency in that illfated A-330 control system (side stick etc), complemented with a few complicated instruments/sensors (say Pitot Tube nightmare at high altitude).
It had nothing to do with the sidesticks.
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#24
by
Jim
on 15 Dec, 2012 17:38
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Pilot errors
Not all were/are pilot errors. There was a design deficiency in that illfated A-330 control system (side stick etc), complemented with a few complicated instruments/sensors (say Pitot Tube nightmare at high altitude).
Those examples were pilot errors and training deficiencies, especially the A-330. Anyways, your examples were not applicable to Breeze.
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#25
by
Galactic Penguin SST
on 15 Dec, 2012 17:42
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#26
by
kevin-rf
on 16 Dec, 2012 12:07
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If true, does that mean it still has four minutes of propellants on board and at some point in the future we will again see a violent debris producing event?
Considering the perigee is 3000 km, any debris will be up for a very, very long time.
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#27
by
Danderman
on 17 Dec, 2012 02:19
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If true, does that mean it still has four minutes of propellants on board and at some point in the future we will again see a violent debris producing event?
Considering the perigee is 3000 km, any debris will be up for a very, very long time.
All the more reason to plumb the settling thrusters into the main prop tanks; apart from being able to continue the mission, burning prop is the best way to empty a prop tank.
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#28
by
kevin-rf
on 17 Dec, 2012 03:32
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Maybe not, the settling thrusters are usually pressure fed, meaning they most likely have much lower ISP. Also, with the exception on the final (be it fourth,fifth, or 100th burn), what orbit do you shoot for? Unless the failure happens (like the latest failure) near the end of the final burn, the mission will require the satellite saving itself to some degree. Remember two of the Briz failures where guidance issues and not engine/pressurization failures
Don't pressure fed systems usually operate ay higher pressure? Heavier dry mass then...
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#29
by
Jim
on 17 Dec, 2012 03:42
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If true, does that mean it still has four minutes of propellants on board and at some point in the future we will again see a violent debris producing event?
Considering the perigee is 3000 km, any debris will be up for a very, very long time.
All the more reason to plumb the settling thrusters into the main prop tanks; apart from being able to continue the mission, burning prop is the best way to empty a prop tank.
Not feasible with current propellant combination. UDMH is not monoprop
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#30
by
Danderman
on 17 Dec, 2012 03:46
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Maybe not, the settling thrusters are usually pressure fed, meaning they most likely have much lower ISP. Also, with the exception on the final (be it fourth,fifth, or 100th burn), what orbit do you shoot for? Unless the failure happens (like the latest failure) near the end of the final burn, the mission will require the satellite saving itself to some degree. Remember two of the Briz failures where guidance issues and not engine/pressurization failures
Don't pressure fed systems usually operate ay higher pressure? Heavier dry mass then...
First off, I am not suggesting that use of the settling thrusters by themselves should be able to achieve the final orbit, the goals would be to achieve some extra delta-V (as compared with the current off-nominal procedure), and to burn off the remaining prop. Using the avail tank pressure in the main prop tanks to feed the settling thrusters, especially once there is some acceleration, should be enough to accomplish the two goals.
As for the guidance failures, remember that these failures had the effect of shutting down the system. A simple uplink command channel could be used to mitigate the impact of the system dying because of guidance failures (not to stop the failure in process, but to recover some delta-V after the system were shut down from guidance problems).
Usually, the best practice is: if it ain't broke, don't fix it. However Briz IS broken. It needs to be fixed.
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#31
by
Jim
on 17 Dec, 2012 04:09
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Maybe not, the settling thrusters are usually pressure fed, meaning they most likely have much lower ISP. Also, with the exception on the final (be it fourth,fifth, or 100th burn), what orbit do you shoot for? Unless the failure happens (like the latest failure) near the end of the final burn, the mission will require the satellite saving itself to some degree. Remember two of the Briz failures where guidance issues and not engine/pressurization failures
Don't pressure fed systems usually operate ay higher pressure? Heavier dry mass then...
First off, I am not suggesting that use of the settling thrusters by themselves should be able to achieve the final orbit, the goals would be to achieve some extra delta-V (as compared with the current off-nominal procedure), and to burn off the remaining prop. Using the avail tank pressure in the main prop tanks to feed the settling thrusters, especially once there is some acceleration, should be enough to accomplish the two goals.
As for the guidance failures, remember that these failures had the effect of shutting down the system. A simple uplink command channel could be used to mitigate the impact of the system dying because of guidance failures (not to stop the failure in process, but to recover some delta-V after the system were shut down from guidance problems).
Usually, the best practice is: if it ain't broke, don't fix it. However Briz IS broken. It needs to be fixed.
An uplink command channel is far from simple.
A. It is a major avionics change. It is more than just adding a receiver. The guidance system has to be able to accept the command. That means computer changes and code changes
B. having a receiver doesn't mean there is a transmitter in line of sight or in range to send the command
B. still is a major conop change and it has to be planned and practiced and real time tools have to be developed to determine the course of action
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#32
by
hop
on 17 Dec, 2012 04:25
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All the more reason to plumb the settling thrusters into the main prop tanks; apart from being able to continue the mission, burning prop is the best way to empty a prop tank.
If preventing the tanks from popping is the goal, vent valves timed to open N hours after the nominal end of mission would seem like a much more practical approach. Or depending on the details, something completely passive like a rupture disk might do the trick.
This entire premise of this thread seems rather silly to me. The response to a failure should be based on the results of the failure investigation. Given the number of recent failures, it's certainly fair to suggest the investigation should go beyond the immediate cause of the current failure and look at broader organizational and design issues.
If the root cause is poor quality control, adding more complexity to the vehicle seems unlikely to improve the overall success rate much. You might get more recovery options, but you also get more places to mess up.
While there might be merit to making a stage like Briz more recoverable, there would also be considerable cost in engineering, complexity, and possibly mass. If you have those resources to expend, the correct course would be to do trades to determine where you get the most value. I don't see an justification for assuming your proposal would automatically be the best choice.
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#33
by
kevin-rf
on 17 Dec, 2012 13:20
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One thing I have never understood about the fuel choices here, how quickly do they boil off in vacuum. Some fluids do not immediately flash to gas when exposed to a vacuum. So does depressurizing the tanks and venting to vacuum result in the spent stage being coated with two different caustic sludges that burn on contact?
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#34
by
Prober
on 17 Dec, 2012 13:40
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Maybe not, the settling thrusters are usually pressure fed, meaning they most likely have much lower ISP. Also, with the exception on the final (be it fourth,fifth, or 100th burn), what orbit do you shoot for? Unless the failure happens (like the latest failure) near the end of the final burn, the mission will require the satellite saving itself to some degree. Remember two of the Briz failures where guidance issues and not engine/pressurization failures
Don't pressure fed systems usually operate ay higher pressure? Heavier dry mass then...
First off, I am not suggesting that use of the settling thrusters by themselves should be able to achieve the final orbit, the goals would be to achieve some extra delta-V (as compared with the current off-nominal procedure), and to burn off the remaining prop. Using the avail tank pressure in the main prop tanks to feed the settling thrusters, especially once there is some acceleration, should be enough to accomplish the two goals.
As for the guidance failures, remember that these failures had the effect of shutting down the system. A simple uplink command channel could be used to mitigate the impact of the system dying because of guidance failures (not to stop the failure in process, but to recover some delta-V after the system were shut down from guidance problems).
Usually, the best practice is: if it ain't broke, don't fix it. However Briz IS broken. It needs to be fixed.
Danderman is right, Britz is broken. Britz IMHO, needs to default to release payload, and deorbit. Mitigating more space trash should be an issue at this point.
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#35
by
hop
on 17 Dec, 2012 20:15
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Britz IMHO, needs to default to release payload, and deorbit. Mitigating more space trash should be an issue at this point.
Huh? De-orbit requires the stage to be pretty much fully functional, in which case it should complete the mission. Briz would not have the dV to de-orbit late in the mission.
Passivating the things that create large debris clouds is a much more realistic (i.e. possible in the real world) option.
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#36
by
woods170
on 17 Dec, 2012 20:38
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Usually, the best practice is: if it ain't broke, don't fix it. However Briz IS broken. It needs to be fixed.
Danderman is right, Britz is broken.
No, Briz is not broken. What is much more likely is that the QA chain around Briz is broken. The design itself is sound, as proven by the fact that over 80 percent of the Briz missions had no failures whatsoever. The current failure rate of 18 percent is consistent with flaws in quality assurence.
Other indicator pointing to quality issues is random failures on other launch systems, such as the fairly recent failure of a Soyuz-U launcher, carrying a Progress spacecraft. That failure was a quality issue as well.
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#37
by
Prober
on 17 Dec, 2012 20:44
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#38
by
kevin-rf
on 18 Dec, 2012 01:09
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From Prober's article
Palme and Kramer said that despite its premature shutdown, the Breeze-M stage that failed Dec. 9 completed the passivation procedures that the stage performs on all its missions and is not at risk of exploding in orbit.
Didn't they also make that claim with the recently RUD'd previous failure? Now saying, well this one dropped the drop tank, so it won't RUD... Glad the author took them to task with the claims.
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#39
by
Danderman
on 27 Feb, 2013 23:23
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If the problems with Briz-M are due to the long burn time of the engine required to go through the 15 tons of prop (it's a very small engine, so it has to burn for a long time to get satellites to GTO), then another approach would be to somehow affix small engines to the large auxiliary propellant tank (APT). Even a series of 100 kg engines would significantly reduce Briz-M engine burn time.
Huh? De-orbit requires the stage to be pretty much fully functional, in which case it should complete the mission. Briz would not have the dV to de-orbit late in the mission.