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Topic: Soyuz Vs Shuttle?
Username: Mt99
Posted 2006-09-20 20:30:45 and read 17137 times.

Enough of A vs B..

As the first woman space tourist docks with the space station, i am wondering on which ship would u much rather travel to space.

For me.. id probably go with the Soyuz.. Seems safer.

Seems like you cant trust the shuttle fleet anymore. It Losses more part than Steve Guttenmberg.

Topic: RE: Soyuz Vs Shuttle?
Username: RichardPrice
Posted 2006-09-20 20:50:58 and read 17145 times.

Remember that Soyuz is more than the capsule, its a complete system used for manned, unmanned and satellite launches. To date -

97 manned missions (Soyuz-1 to Soyuz TMA-8)

106 supply missions (Progress space craft)

A total of over 850 launches (Soyuz launcher vehicle) with very few failures.

Im going to go with Soyuz.

Topic: RE: Soyuz Vs Shuttle?
Username: DfwRevolution
Posted 2006-09-20 21:15:56 and read 17129 times.

Quoting Mt99 (Thread starter):
For me.. id probably go with the Soyuz.. Seems safer.

Statistically, both have a 2% rate of Loss of Crew.

If you're given the option to be a space tourist on either vehicle, it's Shuttle hands down. It has the greatest internal volume of any spacecraft and more window space than Soyuz. Crew comforts are noteably superior.

Quoting Mt99 (Thread starter):
Seems like you cant trust the shuttle fleet anymore.

That's because the Shuttle is given an almost unlimited degree of scrutiny to insure it is opperating properly. Everything about the Shuttle makes the news lately because STS-115 is only the 3rd post-Columbia flight.

And really, there has never been a better time to fly the Shuttle. It's the safest it has ever been.

Had you passed your assumption in November 2002 when Endeavour flew the last mission before Columbia was lost, you would have likely said that the Shuttle was a safe vehicle with no losses since Challenger in 1986. Likewise, just prior to Challenger STS-51L, the Shuttle had flown 24 successful missions.

Would you rather have flown before those incidents marred the Shuttle's safety record, or would you rather fly now that they have been fixed? Believe me when I say Soyuz has had some very close calls over the years as well.

Topic: RE: Soyuz Vs Shuttle?
Username: Chksix
Posted 2006-09-20 21:38:11 and read 17112 times.

I'd rather go on the shuttle aswell. Specially on re-entry and landing up on the flightdeck.

Agree that it's safer than ever now.

Topic: RE: Soyuz Vs Shuttle?
Username: Thorny
Posted 2006-09-21 00:58:36 and read 17081 times.

Here are the statistics. I went ahead and counted both STS-115 and Soyuz TMA-8 although both are still in flight.

Soyuz (1967-Present)
------------------------------
Flights: 95
Failures: 4 (2 non-fatal)
Failure Rate: 4.21%

Cosmonauts Flown: 228
Fatalities: 4
Fatality Rate: 1.75%

Shuttle (1981-Present)
------------------------------
Flights: 116
Failures: 3 (1 non-fatal)
Failure Rate: 2.59%

Astronauts Flown: 692
Fatalities: 14
Fatality Rate: 2.02%

Soyuz Failures:
Soyuz 1 (1967), Soyuz 11 (1971), Soyuz 18A (1975, Non-Fatal), Soyuz T-10A (1983, Non-Fatal)

Shuttle Failures:
STS-51L (1986), STS-83 (1997, Non-Fatal), STS-107 (2003)

Topic: RE: Soyuz Vs Shuttle?
Username: Ptrjong
Posted 2006-09-21 01:40:07 and read 17069 times.

Which one comes with better IFE and PTVs and a free can of Coke?
(Typical a.net forum 'aviation enthousiast' question) biggrin 

Peter

Topic: RE: Soyuz Vs Shuttle?
Username: Mke717spotter
Posted 2006-09-21 01:51:23 and read 17063 times.

Quoting Thorny (Reply 4):
STS-83 (1997, Non-Fatal),

What happened in that one?

Topic: RE: Soyuz Vs Shuttle?
Username: DfwRevolution
Posted 2006-09-21 01:58:12 and read 17061 times.

Quoting Mke717spotter (Reply 6):
What happened in that one?

#2 Fuel cell malfunction required premature landing only 3 days into a 15 day mission. Reflown as STS-94

There was also an SSME failure on STS-51F that caused an Abort-To-Orbit

Topic: RE: Soyuz Vs Shuttle?
Username: Thorny
Posted 2006-09-21 02:17:37 and read 17055 times.

Quoting DfwRevolution (Reply 7):
There was also an SSME failure on STS-51F that caused an Abort-To-Orbit

Yes, STS-2 and STS-44 both returned early, but the lion's share of the mission's objectives were accomplished nevertheless, as were STS-51F's, so they aren't considered failures. STS-83 however, was a Spacelab flight that accomplished very little and really must be considered a failure.

Topic: RE: Soyuz Vs Shuttle?
Username: Lnglive1011yyz
Posted 2006-09-21 02:17:58 and read 17055 times.

While the logic says to go with the Soyuz, simply due to the number of flights, and the low-mortality rate when compared with the Shuttle, I must say that the Shuttle looks like it's much more 'fun' going into orbit on..

I'd probably go with the Shuttle.

1011yyz

Topic: RE: Soyuz Vs Shuttle?
Username: BEG2IAH
Posted 2006-09-21 04:07:33 and read 17028 times.

I would go with both, but chances are zero.  Smile

While on a (9th level) tour in NASA this summer, I asked them if they accepted volunteers. The answer was: nay.

BEG2IAH

Topic: RE: Soyuz Vs Shuttle?
Username: Bobster2
Posted 2006-09-21 04:54:45 and read 17012 times.

Quoting Thorny (Reply 4):
Failures: 3 (1 non-fatal)
Failure Rate: 2.59%

There were five aborts within three seconds of launch. If you count those as failures the statistics get worse.

Topic: RE: Soyuz Vs Shuttle?
Username: DfwRevolution
Posted 2006-09-21 05:57:34 and read 16996 times.

Quoting Bobster2 (Reply 11):
There were five aborts within three seconds of launch. If you count those as failures the statistics get worse.

But how does a count-down abort in any way contribute to mission failure numbers?

Topic: RE: Soyuz Vs Shuttle?
Username: Centrair
Posted 2006-09-21 07:55:52 and read 16982 times.

Hmmm

Shuttle for roomyness, bigger windows, better waste management system, required piloting skills and a front view landing.

Soyuz for unique ingress, egress, one heck of drop from the sky and seeing how small the body can get when cramed into a seat. (my knees don't bend that much for very long).

Soyuz has a lot of exoticness to me. But sitting in a Shuttle means you can sit where some legends have sat.

I will take C: The Enterprise only problem is 1 bathroom for so many crew members.

Topic: RE: Soyuz Vs Shuttle?
Username: CURLYHEADBOY
Posted 2006-09-21 14:52:51 and read 16952 times.

One of the two fatal Soyuz accidents was due to human error, I'm talking about the one that got depressurized on re-entry, am I right?

Topic: RE: Soyuz Vs Shuttle?
Username: Thorny
Posted 2006-09-21 14:52:54 and read 16952 times.

Quoting Bobster2 (Reply 11):
There were five aborts within three seconds of launch. If you count those as failures the statistics get worse.

Yes they would, but why on earth would you count a launch scrub as a mission failure? That's not the mainstream definition of a mission failure.

Generally, a mission failure is when a vehicle flies but does not complete its mission. The only exception I know of, and even that is often argued, is Apollo 1, destroyed during a Plugs-Out Test a few weeks before scheduled launch. In all the other cases of a post-ignition abort (Gemini 6, STS-41D, etc.) the mission did eventually launch and was successful.

I should point out that Soyuz 15, Soyuz 33, and Soyuz T-8 should probably also be classified as mission failures, since all three failed to dock with a Salyut space station as intended.

Topic: RE: Soyuz Vs Shuttle?
Username: TheSonntag
Posted 2006-09-21 15:37:38 and read 16939 times.

We should also add reliability in the equation. I would say the following:

Safety: Both are equal, but the Soyuz accidents happened a long time ago. 1:1

Capabilities: Shuttle wins this one easily. However, Soyuz could land on soil many years before any US technology did that. 3:1 (2 points because of the payload and comfort difference)

Cost: I cannot say whether Soyuz is more cost effective, but it seems so. 3:2

Reliability: Soyuz wins obviously, even if we do not have completely reliable figures here compared to the Shuttle. 3:3

So the result is 3:3 A fair draw if you ask me. Both systems are needed for the ISS, and they both have their drawbacks.

Topic: RE: Soyuz Vs Shuttle?
Username: Thorny
Posted 2006-09-21 15:49:17 and read 16935 times.

Quoting TheSonntag (Reply 16):
Safety: Both are equal, but the Soyuz accidents happened a long time ago. 1:1

Until STS-107, you could say the same for Shuttle. It had been 17 years and 88 flights since the last Shuttle accident.

Soyuz has only flown 85 flights since the Soyuz 11 disaster.

Topic: RE: Soyuz Vs Shuttle?
Username: Bobster2
Posted 2006-09-21 23:21:55 and read 16857 times.

Quoting Thorny (Reply 15):
why on earth would you count a launch scrub as a mission failure?

Technically, anytime the SSME's are ignited is counted as a launch. So an abort after ignition means a return to the VAB for engine re-inspection, same as any other launch.

I agree it's not a mission failure, it's only a launch failure. But it's still a distinction that abort is more serious than a hold or simple rescheduling.

Topic: RE: Soyuz Vs Shuttle?
Username: Thorny
Posted 2006-09-22 00:25:12 and read 16840 times.

Quoting Bobster2 (Reply 18):
Technically, anytime the SSME's are ignited is counted as a launch.

No it isn't, as demonstrated by the six Flight Readiness Firings.

Launch is motion off the pad, not engine ignition. Note that firing up the SSMEs 6.6 seconds before liftoff is done for the express purpose of making sure everything is working right before committing to launch. At the very least, I would say launch begins with Hold-Down Post release, not SSME ignition. The RSLS computer makes sure the three SSMEs are burning properly and if they are, they command SRB ignition and Hold-Down Post release. If they're not, the RSLS halts the launch attempt (the narrowest abort was at T-1.8 seconds.)

And they didn't always roll back to the VAB after the post-ignition aborts. STS-51F didn't. STS-55 didn't.

Quoting Bobster2 (Reply 18):
I agree it's not a mission failure, it's only a launch failure.

No, it's a launch scrub, albeit more dramatic than most.

Topic: RE: Soyuz Vs Shuttle?
Username: Bobster2
Posted 2006-09-22 01:45:33 and read 16824 times.

Quoting Thorny (Reply 19):
Launch is motion off the pad, not engine ignition.

My reference is the NASA web site. They say: "The procedure that has been used on previous aborts treats an RSLS abort after SSME ignition as a launch and to require a complete engine reinspection."

http://science.ksc.nasa.gov/shuttle/...issions/sts-68/mission-sts-68.html

I was wrong about the rollback being required. STS-55 had its engines replaced on the launch pad, a rollback was not needed, but the abort was treated like a launch.

The FRF's are also counted as launches. My reference on that is William Harwoods launch chronology:

http://www.cbsnews.com/network/news/space/stschrono.html

Topic: RE: Soyuz Vs Shuttle?
Username: Bobster2
Posted 2006-09-22 03:03:27 and read 16812 times.

Let me clarify what I've been arguing. My objective is to have a meaningful statistic for the reliability of the shuttle. So my argument is based on the somewhat arbitrary definition that the SSME's should be 100% reliable when they ignite, and I want a statistic that measures how much less than 100% reliable they actually are. I forgive them statistically for problems detected before ignition (scrubs), but I penalize them for problems detected after ignition.

I realize that an abort before the hold-down posts release is not a launch, but for the purpose of keeping meaningful statistics I propose counting the abort after ignition as a launch failure, because it indicates a serious reliability issue.

So NASA gets credit for successful FRF's, but they also get penalized for aborts at T-2 seconds. It's just statistics.

We can also count the STS-51F abort to orbit as a launch failure for statistical purposes even thought the mission was 100% succesful. I hope that doesn't sound totally insane.  

[Edited 2006-09-22 03:14:57]

Topic: RE: Soyuz Vs Shuttle?
Username: DfwRevolution
Posted 2006-09-22 03:52:46 and read 16802 times.

Quoting Bobster2 (Reply 20):
I was wrong about the rollback being required. STS-55 had its engines replaced on the launch pad, a rollback was not needed, but the abort was treated like a launch.

That's because any ignition of the SSME requries certain turn-around procedures before the vehicle can attempt another countdown.

Quoting Bobster2 (Reply 21):
So NASA gets credit for successful FRF's, but they also get penalized for aborts at T-2 seconds. It's just statistics.

Arbitrary statistics that you chose and represent nothing meaningful.

Quoting Bobster2 (Reply 21):
I forgive them statistically for problems detected before ignition (scrubs), but I penalize them for problems detected after ignition.

Many of the relevant engine parameters required for safe opperation of the vehicle can't be measured until the engine fires.

It isn't practical to perform a 20 second FRF before each flight if performance can be verified in 8 seconds and the auto-sequence controller can perform an RSLS abort if necessary.

Topic: RE: Soyuz Vs Shuttle?
Username: Thorny
Posted 2006-09-22 04:13:01 and read 16794 times.

Quoting Bobster2 (Reply 20):
My reference is the NASA web site. They say: "The procedure that has been used on previous aborts treats an RSLS abort after SSME ignition as a launch and to require a complete engine reinspection."

Nonsense. If NASA considered the FRF flights, they would today have announced the safe landing of the 122nd Shuttle mission, not the 116th. But all NASA references say this week's mission was No.116.

Quoting Bobster2 (Reply 21):
I realize that an abort before the hold-down posts release is not a launch, but for the purpose of keeping meaningful statistics I propose counting the abort after ignition as a launch failure, because it indicates a serious reliability issue.

Of what? The Shuttle system? The system did exactly what it was intended to do... when an engine isn't meeting parameters, it safely aborted the launch sequence. It is a mystery to me how you can lump this in the same category as the Falcon 1 launch, which left the pad with a leaky propulsion system because its brains didn't know any better.

Quoting Bobster2 (Reply 21):
Let me clarify what I've been arguing. My objective is to have a meaningful statistic for the reliability of the shuttle. So my argument is based on the somewhat arbitrary definition that the SSME's should be 100% reliable when they ignite, and I want a statistic that measures how much less than 100% reliable they actually are.

Then failures in flight is the logical measure. The failure rate is 1 in 348.

Quoting Bobster2 (Reply 21):
Let me clarify what I've been arguing. My objective is to have a meaningful statistic for the reliability of the shuttle. So my argument is based on the somewhat arbitrary definition

Very arbitrary. So abitrary that it is used to describe the success rate of absolutely no other launchers in the world. NASA and nearly all historians consider both Gemini and Apollo to have been 100% successful from a launch standpoint. But Gemini 6 aborted on the pad after engine ignition and rising a few inches off the pad. Apollo had engines out on Apollo 6 and Apollo 13. Many launch vehicles use multiple engines precisely to give them engine-out performance and improve the odds of a successful launch. However, your definition penalizes vehicles which have multiple engines for redundancy and other vehicles which bring up the engines to full thrust before committing to flight.

Cutting off engines before committing to flight is not a launch failure or a mission failure, it is a pre-flight launch abort.

Topic: RE: Soyuz Vs Shuttle?
Username: Alessandro
Posted 2006-09-22 09:36:47 and read 16759 times.

Start I would prefer the Sojuz and landing the Shuttle, one Sojuz capsule drifted and landed on a cliff, a close call.

Topic: RE: Soyuz Vs Shuttle?
Username: Thorny
Posted 2006-09-22 20:20:43 and read 16694 times.

Quoting CURLYHEADBOY (Reply 14):
One of the two fatal Soyuz accidents was due to human error, I'm talking about the one that got depressurized on re-entry, am I right?

No, Soyuz 11 was mechanical failure, not human error. A vent valve opened accidentally when the Soyuz's Orbital Module was jettisoned prior to re-entry. The crew tried to save themselves by closing the vent valve, but didn't have enough time to get to it before they lost consciousness. They were not wearing spacesuits and died of decompression/asphyxiation.


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