Quote from: veblen on 06/02/2014 11:31 pmQuote from: AJW on 06/02/2014 10:54 pmQuote from: Jim on 05/30/2014 08:00 pmNot 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.
Quote from: AJW on 06/02/2014 10:54 pmQuote from: Jim on 05/30/2014 08:00 pmNot 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).
Quote from: Jim on 05/30/2014 08:00 pmNot 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!
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.
Quote from: RanulfC on 05/30/2014 07:53 pmSecondly 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" restrictionsNot 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.
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
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.
Did the shuttle every miss the runway? Energy management is not an issue.
Quote from: Prober on 06/02/2014 11:51 amhuh? 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.
huh? where's the video on the V2 parachute drop test ?
there may be ANY concession to aesthetic in D-V2 design?
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.
Quote from: Jim on 05/30/2014 08:00 pmQuote from: RanulfC on 05/30/2014 07:53 pmSecondly 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" restrictionsNot 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. Quote from: veblen on 06/03/2014 03:51 pmIt 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.
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.
Quote from: veblen on 06/03/2014 07:34 pmOkay 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.
936
Author
Topic: SpaceX: Dragon V2 Unveil - Discussion/Party Thread. (Read 426336 times)
