Author Topic: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.  (Read 426336 times)

Offline veblen

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1060 on: 06/03/2014 03:51 pm »
Not true, what dead zones will  Dream Chaser will have? Its abort system is used as an orbital insertion and deorbit system, since the wings will cover landing.

Not the dead zones you are thinking of, but DC gives you only one shot at the LZ and no ability to go around so zero margin for error and no backup plan.  The video was cut short, but we are already aware of one significant DC failure mode.  If you have any control surface issue during reentry, even Oscar Goldman can't put you back together.  Columbia was a lifting body, and whether an ice strike or debris impact, a capsule is safer and stronger than a system that relies on exposed flight control surfaces.   Challenger would have been survivable with an LAS, but due to design, weight, complexity, cost & delays of adding an escape capsule to a lifting body, this wasn't done, but when you start with a capsule, you are already ahead of the curve.  Now combine parachutes, the system with the greatest proven safety record, and add propulsive landing and you are again ahead.  Add the ability to land safely on both land and water save the issues with required emergency landing sites and TAL.  When looking at dead zones, these must be included as well.

I'll save Jim the time with the following:

Wrong!

Unsubstantiated!

Emotional response!

Irrelevant!

That part about "any control surface issues during re-entry" applies to all s/c. Including capsules. I just read about it wrt to Soyuz and a bolt that kept a service module connected to the crew capsule which screwed up the re-entry trajectory (went ballistic).
You just proved his point since that flight was non-fatal.

It was a close call according to the cosmo's account. Lets be frank the DC crash was survivable too, but instead it is mocked above with references to "The 6 Million Dollar Man".

New gloss, same as the old gloss.
« Last Edit: 06/03/2014 06:52 pm by veblen »

Offline AJW

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1061 on: 06/03/2014 06:20 pm »

Secondly because "propulsive-flight-control" (focusing on the whole flight envelope rather than any one "phase" here) is by its nature a safer, more reliable system from end-to-end. Why? Parachutes and wing (lifting) flight both have unavoidable "dead-zones" where they will not function properly. Specifically they have an altitude and minimum-speed requirement respectivly below which they can't function. Propulsive is a "zero-to-maximum" system at any point. If it works at all, as long as it has propellant there are no "dead-zone" restrictions

Not true, what dead zones will  Dream Chaser will have? Its abort system is used as an orbital insertion and deorbit system, since the wings will cover landing.


It was a close call according to the cosmo's account. Lets be frank the DC crash was survivable too, but instead it is mocked above with references to "The Bionic Man".

New gloss, same as the old gloss.

The reference was relevant and intentional based on this thread's title.   DC is subject to the same issues as the M-2/F2 which lost airspeed, was unable to raise the nose of the craft and missed the runway.  Gliders will always be subject to dependencies of trading altitude for distance and/or speed.  When you run out of altitude, you have nothing left to trade.  Jim stated that DC had no dead zones, and the M-2/F2 demonstrated multiple issues.  Inability to go around, inability to reach a runway, inability to recover from low-altitude stall, and the DC will be subject to these same issues.  DV2 uses parachutes as a backup and I haven't spotted this on DC.  Water landings are also a concern, so to me a dead zone includes any circumstance when you are unable to make a safe landing which is why I mentioned Shuttle ELS & TAL.

Offline Jim

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1062 on: 06/03/2014 06:48 pm »

The reference was relevant and intentional based on this thread's title.   DC is subject to the same issues as the M-2/F2 which lost airspeed, was unable to raise the nose of the craft and missed the runway.  Gliders will always be subject to dependencies of trading altitude for distance and/or speed.  When you run out of altitude, you have nothing left to trade.  Jim stated that DC had no dead zones, and the M-2/F2 demonstrated multiple issues.  Inability to go around, inability to reach a runway, inability to recover from low-altitude stall, and the DC will be subject to these same issues.

Did the shuttle every miss the runway?  Energy management is not an issue.

Offline Lee Jay

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1063 on: 06/03/2014 07:09 pm »
Did the shuttle every miss the runway?  Energy management is not an issue.

STS-37 landed short, but the lessons learned from that event made that far less likely in the future.

Offline Prober

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1064 on: 06/03/2014 07:13 pm »
huh?  where's the video on the  V2 parachute drop test ?
NASA released the video a couple of months ago.  But that V2 was boilerplate, without the new shape and SD pods.  But it did have the new nose cap, which confused many people at the time.

thx for the memory jog
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Offline pagheca

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1065 on: 06/03/2014 07:16 pm »
there may be ANY concession to aesthetic in Dragon V2 design?
« Last Edit: 06/03/2014 07:25 pm by pagheca »

Offline cscott

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1066 on: 06/03/2014 07:20 pm »
there may be ANY concession to aesthetic in D-V2 design?

There are some nifty logos!  And the seats look pretty sharp.

But the white/black coloring is functional, and the moldline is functional (probably tested in a hypersonic wind tunnel already), etc.  Pretty much everything on the outside is dictated by functional concerns.

Offline Lee Jay

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1067 on: 06/03/2014 07:25 pm »
The video was cut short, but we are already aware of one significant DC failure mode.  If you have any control surface issue during reentry, even Oscar Goldman can't put you back together.

That's false.  DC has control surface redundancy, and triple redundancy for each surface.

Offline veblen

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1068 on: 06/03/2014 07:34 pm »

Secondly because "propulsive-flight-control" (focusing on the whole flight envelope rather than any one "phase" here) is by its nature a safer, more reliable system from end-to-end. Why? Parachutes and wing (lifting) flight both have unavoidable "dead-zones" where they will not function properly. Specifically they have an altitude and minimum-speed requirement respectivly below which they can't function. Propulsive is a "zero-to-maximum" system at any point. If it works at all, as long as it has propellant there are no "dead-zone" restrictions

Not true, what dead zones will  Dream Chaser will have? Its abort system is used as an orbital insertion and deorbit system, since the wings will cover landing.


It was a close call according to the cosmo's account. Lets be frank the DC crash was survivable too, but instead it is mocked above with references to "The Bionic Man".

New gloss, same as the old gloss.

The reference was relevant and intentional based on this thread's title.   DC is subject to the same issues as the M-2/F2 which lost airspeed, was unable to raise the nose of the craft and missed the runway.  Gliders will always be subject to dependencies of trading altitude for distance and/or speed.  When you run out of altitude, you have nothing left to trade.  Jim stated that DC had no dead zones, and the M-2/F2 demonstrated multiple issues.  Inability to go around, inability to reach a runway, inability to recover from low-altitude stall, and the DC will be subject to these same issues.  DV2 uses parachutes as a backup and I haven't spotted this on DC.  Water landings are also a concern, so to me a dead zone includes any circumstance when you are unable to make a safe landing which is why I mentioned Shuttle ELS & TAL.

Okay 30 years of successful shuttle landings (some blown tires) and anyway ever heard of the Gimli Glider? How about the AirTransat airbus flight landing in the Canaries? These are big commercial airliners that are supposed to do powered landings, but they ran out of fuel and had to glide to safety. Which they did, successfully. Plus I just find it amusing that concerns over hpl are kind of dismissed but gliding to a landing is bad. This is the EM effect in action. He didn't like/select/develop a s/c that glides unpowered to a landing, so therefore it is to be poo-poohed.

Offline Elmar Moelzer

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1069 on: 06/03/2014 07:52 pm »
Okay 30 years of successful shuttle landings (some blown tires) and anyway ever heard of the Gimli Glider? How about the AirTransat airbus flight landing in the Canaries? These are big commercial airliners that are supposed to do powered landings, but they ran out of fuel and had to glide to safety. Which they did, successfully. Plus I just find it amusing that concerns over hpl are kind of dismissed but gliding to a landing is bad. This is the EM effect in action. He didn't like/select/develop a s/c that glides unpowered to a landing, so therefore it is to be poo-poohed.
No, I think the whole thing came up as a response to a poster who stated that SpaceX method of propulsive landing was inferior to others like the DC... So it was not intended to bash DC but to defend Dragon.
Personally, I cant understand why some people seem to have a problem with powered landing. We used it successfully (every time) to land Astronauts on the moon decades ago. Technology has only improved since then.
« Last Edit: 06/03/2014 07:54 pm by Elmar Moelzer »

Offline cscott

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1070 on: 06/03/2014 07:56 pm »
This is the EM effect in action. He didn't like/select/develop a s/c that glides unpowered to a landing, so therefore it is to be poo-poohed.

No, it's just the result of a rather tedious flame war where each side is selectively quoting and then shifting their argument so that nothing actually makes sense in isolation any more.

I *think* the original point was something about how hauling SuperDracos to orbit and then reusing them for propulsive landing had the nice benefit that they could be used to recover from second-stage failures.  Then we got into a tedious discussion of whether second-stage failures were common, or if they happened whether you needed the thrust of a superdraco to escape for them or whether ordinary RCS was enough, then some people generalized to talking about dead zones, then people felt compelled to stretch their argument by saying that Dragon V2 was the *only* vehicle without dead zones, and now we've circled round to the old rockets-vs-wings argument.

Sigh.

Offline veblen

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1071 on: 06/03/2014 08:21 pm »
Okay 30 years of successful shuttle landings (some blown tires) and anyway ever heard of the Gimli Glider? How about the AirTransat airbus flight landing in the Canaries? These are big commercial airliners that are supposed to do powered landings, but they ran out of fuel and had to glide to safety. Which they did, successfully. Plus I just find it amusing that concerns over hpl are kind of dismissed but gliding to a landing is bad. This is the EM effect in action. He didn't like/select/develop a s/c that glides unpowered to a landing, so therefore it is to be poo-poohed.
No, I think the whole thing came up as a response to a poster who stated that SpaceX method of propulsive landing was inferior to others like the DC... So it was not intended to bash DC but to defend Dragon.
Personally, I cant understand why some people seem to have a problem with powered landing. We used it successfully (every time) to land Astronauts on the moon decades ago. Technology has only improved since then.

That will need to be the case because Dragon2 will land in earth's much stronger (6x?) gravity and thick oxygen/nitrogen atmosphere, unlike the moon's vacuum.

Offline Rocket Science

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1072 on: 06/03/2014 08:40 pm »
The Moon argument is a bit of a red herring... how else are you going to land on it, not many options...? Carry on... ;D
"The laws of physics are unforgiving"
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Offline veblen

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Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1073 on: 06/03/2014 08:41 pm »
A Canadian band, out of Montreal, I prefer Saga or The Box. MWH were okay.
« Last Edit: 06/03/2014 08:43 pm by veblen »

Offline Chris Bergin

Re: SpaceX: Dragon V2 Unveil - Discussion/Party Thread.
« Reply #1074 on: 06/03/2014 09:09 pm »
Right, that locked this thread.

We have the update thread, the video thread and the Garrett thread to use.

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