|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
Greg D. Moore (Strider) wrote: "Rusty" wrote in message oups.com... At one time they could design and build the Saturn V and land on the moon in 8-years. Now they have trouble designing a rocket that can carry a capsule to orbit. True, but money was no object then. I don't think money is the thing stopping them now. They can't even design a rocket that works on paper. Rusty |
#12
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
Pat Flannery wrote: Is the problem the second stage coming in too heavy, or is there a ISP problem with it? Yes and yes. The problem arose when the powerful and efficient SSME was droipped in favor of the lower-thrust, lower-Isp J-2X. Somethign to do about SSME's exploding when you try to air-start them (ou'd think that would have been brought up sooner...). With the lower-performing J-2, there is a need for more propellant for the same delta-V, and more propellant needed to overcome greater gravity losses due to lower T/W. So the 4-segment RSRM had to grow to 5 segments in order to put the upper stage at roughly the same point on the launch curve. This should have never gotten to this point, and if they have this sort of problems with Ares I, God knows how Ares V is going to go wrong, as that has a lot more variables in its design. It also has a lot more margin for growth, and was meant to have J-2X's from the get-go. |
#13
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
Pat Flannery wrote: They know the thing won't meet specifications even as they propose it, The Stick as proposed would almost certainly have worked, if the SSME could have been made air startable. Wasn't ATK that decided to go with a relatively weeny upper stage engine. |
#14
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
In article ,
Pat Flannery wrote: This turkey is now adding an albabtross to its own body. This one throws me. The extended SRB should have been a easily calculated quantity based on Shuttle experience. Is the problem the second stage coming in too heavy, or is there a ISP problem with it? The fundamental problem is simply that a single SRB is a lousy first stage. Lots of thrust, but not great Isp, so the second stage has to do a lot of the work. Heavy but skinny, so the second stage has to be skinny too -- a problem for a stage that needs lots of bulky LH2, and also it limits your engine options because there's no *room* for a multi-engine cluster in such a narrow stage. Short of resorting to seriously unconventional configurations, I suspect the only way to save this turkey would be to ditch the idea of getting to orbit with two stages -- a perfectly reasonable idea, but not if the first is a shuttle SRB -- and concede that the Porklauncher IB has to have three stages, and the second has to be LOX/kerosene rather than LOX/LH2. But my guess would be that the hydrogen religion is too deeply entrenched by now for MSFC to swallow that. I don't think they're going to make this one work without rethinking at least one major past decision -- something they've never been good at. So they've got a choice between using an EELV variant for crew launches, or biting the bullet and going straight to the Porklauncher V. I'd guess they will do the latter, just because the former smacks much too much of admitting defeat. -- spsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | |
#15
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
wrote in message oups.com... Greg D. Moore (Strider) wrote: True, but money was no object then. I think that it's more to the point that there was a well-defined goal to meet, and a timescale to follow; that's about the only situation where government ever gets anything useful done. Without such a goal you could give them an infinite amount of money and they'd still waste it all. Oh, there's a well-defined goal, just no one wants to admit it. It's to spend the pork evenly. If NASA were serious about access to space, they'd continue to fly the Shuttle as old and unsafe as it is and support more private efforts. |
#16
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
"Rusty" wrote in message oups.com... Greg D. Moore (Strider) wrote: "Rusty" wrote in message oups.com... At one time they could design and build the Saturn V and land on the moon in 8-years. Now they have trouble designing a rocket that can carry a capsule to orbit. True, but money was no object then. I don't think money is the thing stopping them now. They can't even design a rocket that works on paper. Sure it is. Enough money and you can make a pig fly. :-) As Scott points out, some of this appears to stem from the descision to not pursue the SSME air-startable version (money doncha know). But going back even further it goes back because they want to "save money" and decided to go with "shuttle derived". Rusty |
#17
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
Greg D. Moore (Strider) wrote: As Scott points out, some of this appears to stem from the descision to not pursue the SSME air-startable version (money doncha know). But going back even further it goes back because they want to "save money" and decided to go with "shuttle derived". And by saving money, we have started down the Shuttle path again....you know, it'll be so safe, that maybe it doesn't really _need_ that escape tower. Pat |
#18
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
Greg D. Moore (Strider) wrote: "Rusty" wrote in message oups.com... Greg D. Moore (Strider) wrote: "Rusty" wrote in message oups.com... At one time they could design and build the Saturn V and land on the moon in 8-years. Now they have trouble designing a rocket that can carry a capsule to orbit. True, but money was no object then. I don't think money is the thing stopping them now. They can't even design a rocket that works on paper. Sure it is. Enough money and you can make a pig fly. :-) As Scott points out, some of this appears to stem from the descision to not pursue the SSME air-startable version (money doncha know). But going back even further it goes back because they want to "save money" and decided to go with "shuttle derived". There may be better ways to put together a launch vehicle using "shuttle derived". Take a look at Nasaspaceflight.com, it's called the "Direct Shuttle Derivative": http://forum.nasaspaceflight.com/for...ts=399&start=1 Rusty |
#19
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
Greg D. Moore (Strider) wrote: But going back even further it goes back because they want to "save money" and decided to go with "shuttle derived". People often think that if a Completely Free launch Vehicle appeared, launched, say, from a runway, that NASA could simply shut down their other launch ops and have cheap space flight. Not so. Closing down the VAB, the Shuttle pads, the processing facilities and all the rest will cost *vast* sums of money. You can't simply turn off the lights and padlock the doors. And further down the road, if "shuttle derived" is completely scrapped, America's ICBM/SLBM fleet is screwed. No RSRM = no ATK-Thiokol = No Minuteman/Trident missiles. |
#20
|
|||
|
|||
NASA Encounters Problems With Ares 1 Launch Vehicle Design
Henry Spencer wrote: Heavy but skinny, so the second stage has to be skinny too -- a problem for a stage that needs lots of bulky LH2, and also it limits your engine options because there's no *room* for a multi-engine cluster in such a narrow stage. Ahem: aerospike or plug cluster. Would fit great. they've got a choice between using an EELV variant for crew launches... Which? The Putinsky or the Fireball? |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Thumbs Down On Ares Vehicle Name | Joe Delphi | History | 40 | July 6th 06 03:10 AM |
NASA Encounters Possible Problems With Crew Launch Vehicle Design | Space Cadet | Space Shuttle | 45 | February 7th 06 03:51 PM |
NASA Encounters Possible Problems With Crew Launch Vehicle Design | Space Cadet | Space Station | 45 | February 7th 06 03:51 PM |
NASA Encounters Possible Problems With Crew Launch Vehicle Design | Space Cadet | Policy | 45 | February 7th 06 03:51 PM |
NASA REFINES DESIGN FOR CREW EXPLORATION VEHICLE | Jacques van Oene | Space Shuttle | 0 | January 11th 06 09:32 PM |