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Lets play a game folks.
Suppose Mr. 'Revenger is flying below a jumbo jet shedding ice. I am flying above it. We both have slipstream--which might fling some mist and small ice particles on both of us--but he has to contend with both gravity and airflow.
Whey he is too stupid to understand this is his problem.
I have a little game here, too.
Let's actually model the orbiter-ET system, rather than making the gross oversimplification of flying above or below a jumbo jet. The ET and orbiter are incredibly close together. The flight angle is fairly close to vertical at the 81 second mark (regardless of whether it's heads-up or heads-down.) The falling foam will have velocity components in both the horizontaland vertical directions. The exact path the foam takes is influenced heavily by the flow field between the orbiter and ET. It's also influenced by the ballistic coefficient of the shape of the piece of foam.
Now it's become a much harder problem. The orientation of the vehicle is seemingly inconsequential when compared to all of the other variables in the equation. The relative trajectories of the foam and orbiter will likely be on a path towards a head-on collision.
Please learn more about physics before you start making inflamatory claims and cutting people down.
If you want to make a military missile, solid or storable liquid propellants are the way to go. Angara just isn't practical for that mission, nor is it designed for it. Besides, South Korea is a fairly peace-loving nation that wants to avoid "rocking the boat" with its nuclear-armed neighbor to the north.
It's pretty safe to say that South Korea, as a technologically advanced nation, is trying to claim its rightful place as a space-capable nation. Is a manned program in the cards? I don't see it happening in the next 20 years aside from perhaps suborbital space tourism. The Angara-based launcher is an important step in the growth of South Korea's tech sector.
We haven't heard much from the VASIMR people in a while. It's a great idea whose time has not yet come. It's worthy of funding, but I don't know if NASA can spare the money as VSE ramps up.
We should view VASIMR as a technology that will probably not reach maturity until after the first Mars landing. Nuclear-ion or nuclear-thermal rockets will fly before VASIMR, but they will open the door to public acceptance of nuclear space propulsion and power. This element, sadly, is a big obstacle between us and exploring the solar system.
The Air Force does want to be able to repalce satellites in a hurry during a space war scenario, but it would rely on smaller launchers like RASCAL to do the job. SDV would take far too long to prepare for launch, and it would need to fill the payload bay with several satellites before it would be ready for launch.
The big unknown quantity with SDV is how much of the shuttle support staff are needed to stay on board to operate the SDV. If this number is high, SDV will not be economical. I do agree that heavy lift will become essential when we reach the colony phase of lunar exploration, but that period may be far enough away that we can design a proper HLLV instead of going "quick and dirty" with SDV.
My thought is that the competing CEV contractor teams should prepare proposals for an SDV. The proposals would be evaluated on the basis of best value, and a decision should be made on whether it will be EELV-only or SDV for cargo and EELV for manned launches.
The irony behind DART, at least according to today's news, is that it may have actually collided with its target spacecraft. This error would be due to noise in the GPS signal. Apparently DART was more successful than first thought.
I quit reading the excerpt after the first paragraph because the bit about the X-38 was a lie. The X-38 was NOT designed to be launched by a medium sized booster, nor would it have made access to space any cheaper. It was a narrowly-defined "point" design for bringing astronauts back to earth from ISS. It would hav been launched by the shuttle. Moreover, the X-38 was designed for astronauts to lie on their backs, and I do not think there was sufficient headroom to install conventional seats.
Sean O'Keefe's role in X-38 was overstated, because the program was effectively cancelled over six months before he came to NASA. The Orbital Space Plane was a more pragmatic outgrowth of the failed Space Launch Initiative, which could have performed both the human launch requirement and the ISS escape mission.
I generally think that OSP would have been a good investment, if not for two things: 1) NASA became enamored with capsules after the loss of Columbia, and 2) Supporting ISS with vehicles like OSP made no sense in the return to the moon and beyond.
X-38, on the other hand, was a cheap-and-dirty effort from the start. Instead of starting with the aerodynamically-superior HL-20, NASA picked the X-24. To make up for the craft's poor low-speed handling, they had to add a complex and heavy parafoil. Even with the parafoil, the landing speed was quite high. The X-38's batteries and consumables were designed to last for only a few hours (after a year or more of storage.) The TPS was the same type of fragile tiles used on the belly of the shuttle. This is not very good when you consider the chances of a debris strike when the X-38 is docked to the ISS for a year or more.
Even if the Russians get the money to build Kliper, the issue of a launch vehicle has yet to be resolved. The Zenit is currently the preferred launcher, but Onega (upgraded Soyuz) is also a candidate.
As the Russians try to move away from the Ukranian-built Zenit, one has to wonder how firmly they are committed to Zenit as a Kliper booster. Of course, delays with Angara will delay or perhaps cancel any decision to phase out Zenit.
My guess is that the Russians are putting all of their efforts into bringing Soyuz to Kourou. Once that's done, they'll ask the Europeans for the money to build Onega. After Onega is built, they'll ask for money to build Kliper.
Regardless of whether the orbiter's belly is facing the earth or facing the sky, it is still vulnerable to debris impacts. Buran is no exception. The relative proximity between the orbiter and the falling foam is the important factor to consider.
Columbia was flying so fast that it ran into the foam--in other words, the foam's velocity relative to the orbiter is what's important. A piece of foam falling off during a rocket's ascent will decelerate so quickly relative to the rocket that an impact becomes probable. Also worth considering is the airflow around the vehicle, and whether the pressure gradient will set the foam on a collision course with the orbiter.
Physics can be dangerous to those who fail to understand it.
Angara's best hope is South Korea, as they have announced plans to license Angara technology for a domestic launcher. Only time will tell if this ever gets off the drawing boards.
For every competitive flyoff that has produced a superior aircraft, there have been great combat planes built without flyoffs. The F-15 and F-14 come to mind. However, the F-14 is not the best example, as it was designed to make up for the deficiencies of the F-111B "Sea Pig." If there had been a competitive flyoff between the General Dynamics and Boeing proposals for the F-111, the controversial and scandalous nature of that acquisition program could have been avoided.
There are good and bad points to the flyoff. My hope is that the losing capsule will still see prodction, perhaps for space tourism. It will be interesting to see a space flyoff because we're entering uncharted territory here.
I think Griffin is right to expect CEV to be developed in a shorter time span than currently budgeted. The only way to cough up the money, though, is to retire the shuttle in the next 2-3 years, not waiting until 2010. I support this move, and I suspect Griffin does too. He has expressed his doubts about the usefulness of ISS in the past, and I suspect he will scale the station back and turn it over to the international partners on a quicker schedule than planned.
I also think we can do without the CEV flyoff in 2008. Some have suggested this is a good way to test TPS and landing technologies, but I feel that these are understood well enough to the point where they can be tested on the full-scale unmanned CEV rather than a boilerplate CEV. We'll save money if the downselect is based on paper proposals rather than expensive hardware. We've never done a spacecraft flyoff before, but I suspect that it will not have as much benefit as an aircraft flyoff.
Griffin is an engineer, so his instinct is to trust his engineers the most. I've found many of the advisory panel's recommendations to be impractical or worthless. If I were a shuttle astronaut I would put zero faith in any of the repair techniques being developed for the shuttle TPS, yet that was part of the CAIB recommendations.
Of course, if they'd have listened to the engineers in Jan '86, Challenger would never have been launched on that cold Tuesday morning. Engineers have a knack for knowing if something is safe to fly. It's part of their job, and NASA engineers are no slouches.
The sad fact is that nobody cares enough about space to let it influence their votes. Just look at Keith Cowing of NASA Watch (an excellent site, IMHO.) He stated flatly that he agrees with VSE and was very critical of John Kerry's vague space plans. Nevertheless, he voted for Kerry anyway for a number of other reasons.
Greg Zsidisn, a Kerry supporter, went so far as to compare his situation to that of von Braun, having to work on space development but only at the whims of the Nazis. The conclusion he drew at the end of his extremist screed is that it's better to sacrifice our space dreams along with our 'mad furher' and to cross our fingers, hoping that the private sector will give us a decent space program.
I find it ironic that the "Angara 100" looks like a redux of Energia, except that it's an in-line launcher now, and it uses kerosene in the core (hydrogen fuel is only used in the upper stage.)
The design looks good on paper but it's highly unlikely to be built. Even the baseline Angara, which was promised for flight by 2004, has been delayed to the 2008-9 time period and may never fly at all.
Buran flew heads up -out of the foam-which would fall down--
And before you get started on the Energiya bankrupted the USSR myth--remember this. N-1 cost as much--and that did not bankrupt the USSR. Instead, the Soviets grew in power--beyond parity in fact.
Please explain your "heads up" assertion. You've said it many times but it makes less and less sense each time you say it. Buran flies in the same position the US orbiter does--on the back of its launch stack, nose pointed in the direction of flight.
And the logical assumption "N-1 didn't bankrupt the USSR, so Energia couldn't have" is quite flawed. You have to consider the strength of the Soviet system at the time of each rocket's development. Many factors unrelated to Energia led to the USSR's decline since the end of N-1. Had Energia been developed in the mid 60's like N-1, it wouldn't have had the same impact that it did in the 80's.
At risk of straying off-topic, I have to say that the fall of the USSR was an accumulation of many factors over the years, not the least of which was the inherently flawed nature of Russian Communism. To say that Afghanistan or Energia or Ronald Reagan (or any other singular explanation) primarily defeated the USSR is a fallacy, but the convergence of these events during the same decade was too much for the USSR to handle.
The EELV proponents seem to be making the same argument von Braun made before 1962, while the SDV supporters are taking the Houbolt route.
For Apollo, Houbolt won out because his approach was feasable with the current technology and it offered the shortest development time. Money was no object back then. Roll the clock forward 43 years, and the world is turned on its head. Money is the limiting factor, while the time it takes is not really an issue. If the return to the moon is a marathon rather than a sprint, an earth-orbit rendezvous approach will likely win out.
We shouldn't feel bad that this debate is still going on. Even though NASa made a choice in 1962, it had to revisit the decision in 1989 for SEI. Originally, EOR won out, but direct landing (using the Saturn-derived "Comet") was the preferred mission mode by 1990. The question was never really settled back then, and that's why it's still festering today.
A side-mounted vehicle only makes sense if the vehicle can be made so safe that crew escape need not be considered. This is a legitimate design philosophy (after all, airliners are so safe that they have no means of passenger emergency egress during flight emergencies,) but for space vehicles we lack the technological maturity to implement it.
It would be foolish to come up with a direct repalcement for Shuttle/Buran. I have no problem with an RLV for hauling heavy cargoes as long as you don't expect to put people in it. I have no problem with a manned spaceplane as long as it's optimized to carry people.
It's important to note that Jeff Bel''s background is indeed in space sciences and astronomy, not in any branch of engineering. The frequent theme in his screeds is that manned spaceflight is too hard, so let's just not do it anymore. It's a very provocative position, but it's not too far away from that of The Planetary Society (robots yes, humans no.) Jeff Bell makes just enough insightful points to win people's attention (especially with his criticism of the OSP when that program was dying down,) but he takes too many logical leaps of faith that are untenable.
Musk reminds me of Andrew Beal, another self-made millionaire who got into the "alt-space" business. Beal's company built an H2O2 / Kerosene engine that could produce 3600 kN of thrust, and he had plans for a similar engine in the F1 class. Yet his business folded in 2000.
Elon Musk has already gotten farther than Beal, but that doesn't mean he's immune to the same fate. His people need to focus on lighting the candle that is the Falcon I. Only then should they start talking about Falcon V and beyond. Otherwise he will be a laughingstock and a flash-in-the-pan.
Unless the pitch loads tear off Dyna-Soar before it can abort.
The arguments against top-mounting a small spaceplane like the X-20 are pretty weak. Yes, these craft would create significant bending moments and stability issues. But all of these can be overcome through smart design.
The Titan III would have been perfectly capable of launching the X-20, and the Titan IV or either heavy EELV could have launched the HL-20. The large strap-on boosters would move the center of pressure aft, compensating for the forward CP shift created by the spacecraft. The manned vehicle's weight would also move the center of gravity forward to the desired position. The pitch moments should not be a problem for a properly-designed rocket's stucture.
The Dyna-Soar / Titan III combo may not look like our preconceived notion of a rocket, but it presents no show-stoppers. It could and should have worked, and it would have given the engineers of the late 60's a realistic idea of how difficult it would be to build, fly, and refurbish a manned spaceplane. Because we skipped over this evolutionary step, we ended up with today's shuttle monstrosity.
Sending two or three military helecopters with medical and security teams is a job small enough for national guard units, and won't be a signifigant expense. Certainly no where near the expense of actually flying or developing the thing... you've got your priorities all wrong.
Of course, NASA would never send out the National Guard to rescue its media-darling astronauts. Bet on NASA to find some pricey, high-profile way to bring the crew back home.
GCNR: In trying to go along with you (shocked disbelief), I still need to know where routine--repeat, routine--crew return capsule landings would take place?
Ask the Russians where their capsules land: in vast patches of open wilderness, on the land. There's no need for US Navy recovery flotillas as long as you have braking rockets and airbags on your capsule.
Check LockMart's press releases and you'll see that they have indeed been working on the systems to enable a landing on terra firma. The Nevada Test Site, where the Genesis capsule was supposed to land, would be an ideal landing zone.
This talk about Apollo 13 makes me think a big tank of hypergolic fuel isn't a good idea. LOX/Methane would be safer than Monomethylhydrazine (MMH).
The explosion occurred not in the propellant tanks for the main engine, but in the oxygen used for the fuel cell. Supposedly NASA has said that the CEV will use solar arrays, not fuel cells, for electrical power.
As for Delta Clipper, the original concept was to launch small "Brilliant Pebbles" interceptors. As the project was transferred from SDIO to NASA, the focus shifted. McDonnell Douglas wanted to use DC-Y / SX-1 to launch commercial satellites in the 10 MT range. The plan never materialized, and McDD tried to use DC-X as a stepping stone to the X-33. McDD lost that contract to LockMart's riskier lifting body approach. The result was two completely wasted programs, the DC-X and X-33.
What is Kliper? A lifting body/capsule hybrid?
Kliper is a class of vehicle known as the "lifting capsule," like the LockMart OSP design. They generate some lift but are not capable of a runway landing like a lifting / winged body. All capsules are capable of generating some lift, but the lifting capsules are optimized for it.
Regarding Hermes, it's really a winged body, not a lifting body like the X-38. It has more in common with Dyna-Soar and the shuttle. Hermes was a promising project, but like so many aerospace efforts was doomed by weight growth, cost growth, and changing mission requirements. It was proposed again for the OSP but was again dropped when NASA started looking at capsules again.
Obviously, lifting bodies fall in between winged vehicles and capsules in terms of their capabilities. Capsules have better volumetric efficiency and heat rejection properties, while winged bodies have lower-stress reentries and better handling capabilities at low speed.
The lifting bodies were supposed to bridge the gap between the two; the point John Becker tried to make is that the heat-rejection and volume advantages claimed by lifting body proponents were greatly exaggerated. He much preferred winged bodies for LEO to earth transportation.
Many of the claimed drawbacks of capsules are just plain incorrect. Capsules can be reusable, as Gemini II proved, and Super Soyuz (Zarya) tried to validate. They can also be optimized for in-space transportation. You want a lighter capsule for transferring people between LEO and the moon? Build your basic earth-to-LEO capsule, but take off the heat shield and substitute lighter components wherever possible. You'd have to launch it unmanned and transfer to it from your earth-to-LEO capsule, but you'd save mass nonetheless.