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I found this anecdote by Keith Cowing of http://nasawatch.com]NASA Watch to be the most telling sign of what we can exect from Mr. Griffin and what kind of integrity he will be bringing to the table:
Editor's personal note: In 1993, during the redesign of Space Station Freedom, many of us felt that the books had been cooked by NASA HQ such that the SS Freedom configuration (Option B) was deliberately handicapped and that the other two options A (MSFC) and C (JSC) were given an unfair advantage. Hardly an apples to apples review. Mike Griffin, who led the Option B effort (headquartered at LaRC) wrote a letter for the record at one point, standing squarely on principle and pointing out the discrepancies and inequities in that review process. That letter received wide circulation - and Mike's NASA career suffered as a result. He was promoted to some pointless job by Dan Goldin and eventually left the agency. I can say from personal experience, that Mike Griffin has demonstrated personal integrity - and did so in a public way that was rather career adverse. I expect he will bring that same integrity to the job of NASA Administrator. As such, yes, at this point, I am biased in this regard.
Griffin sounds like the best guy to be in charge of the VSE, and he is widely respected by both parties in Congress. He's a multitalented engineer and manager who knows what he's talking about.
Has anybody heard what his position is regarding Hubble?
Here is the most relevant part of the space.com article:
Worden, who replaced Griffin as the technology deputy at the Strategic Defense Initiative Organization in the late 1980s, said he does not think Griffin would let his stated preferences for a shuttle-derived heavy-lifter interfere with NASA’s effort to reach an honest conclusion about the best way to go.
“I think he is going to be very open to whatever the best solution is,” Worden said. “He is a superb engineer and he listens to people.”
Let the engineers decide whether SDV or EELV or some combination of both (CEV on EELV, EDS & LSAM on SDV) is the best, most cost-effective solution. Michael Griffin seems like an incredibly able choice for NASA administrator, and I expect him to review all his options when choosing the architecture for VSE.
Boeing designed its Decatur, AL factory to produce 40 CBC's a year. That should be plenty if they plan on fifteen launches per year, even if most of those launches are the heavy variant.
I don't like solids of any size for manned space flights. Even the small solids, like those on the Delta II, are a significant Achillies' Heel. Bear in mind that the last Delta II failure was due to an SRM problem.
For the manned CEV launcher, liquid-only versions of the Atlas V and Delta IV are the only choices. A "heavy" version of the EELV will be expensive, but the safety advantage over solids is appreciable. If Boeing and LockMart can switch to Al-Li tanks and fly a lighter single-core EELV that's capable of launching the CEV, that would be even better. It would probably be cheaper than the Heavy EELV's, and would have 1/3 the chance of a first-stage engine failure.
If the rumors are true about a "down-select" for the EELV, I would say that the victim of the down-select should switch their production line to the uprated model that can launch the manned CEV. That way you're not tasking one company to have two different production lines.
GCNRevenger is right in that we should wait to see the cost estimates before we start taking sides. Can SDV be flown for a significantly lower amount than STS? Will we get economies of scale by making multiple EELV flights? It's hard to say, because we have neither flown an SDV nor pushed the EELV's to their limit (although Boeing and LockMart think they can launch 18 missions per year or so.)
I don't think there's any way of getting around an EELV launch for the CEV. NASA wants a capsule that can blow free of its booster during a launch abort. You could either stick the capsule atop an EELV (or SRB-derived rocket,) or modify the shuttle ET extensively into an in-line launcher (which would be an entirely different animal from the Shuttle-C.)
NASA's modus operandi is safety. The capsule + escape tower setup has a proven record of success (it saved two Soyuz crews.) Yes, it subjects astronauts to high g's, but it's for a tolerably short amount of time. An ejection seat does the same thing.
A side-mount ship, on the other hand, would need to eject perpendicular to the flight path. Clearing the fireball from the booster would be very difficult, perhaps impossible, with current technology. NASA estimates showed that the ejection seats used during STS-1 thru STS-4 would have been incinerated in the plumes from the SRB's. The chances of successful escape would be even lower if the booster exploded like Challenger. The ejection system (whether seats or escape pod) would only be useful in horizontal flight.
The definition of "advanced technology" is very vague. It's unclear if the inflata-habs fall under this restriction.
The "American company" restriction applies only to the 5-man spacecraft that will hopefully be built for the $50 mil prize. Even then, the company need only place its headquarters in the US to qualify.
Latest news from Robert Bigelow is that he's moving his Nautilus inflatable habitat from the Falcon V to the Russian SS-18 Dnepr. Looks like those delays with the Falcon I are starting to hurt Elon & Co.
In response to the most recent comments:
1) Hydrogen engines aren't inherently inefficient at lower altitudes. It's just a matter of what the exhaust pressure is and how closely it matches with the ambient temperature. Extenable nozzles are a solution to the problem.
2) I never proposed reusing the RD-180; I was just making the point that it was possible in theory. Bringing the engine back might make sense if it was part of a winged flyback booster. Otherwise, you can forget about it.
3) When I say that we shouldn't modify existing boosters, I mean that we should not cobble rockets together out of existing stages. For example, we shouldn't make a Delta IV-Atlas V Frankenstein or anything like that. The parts may start off as "off the shelf," but they will evolve into totally different systems by the time the vehicle is integrated. The Saturn I was originally a cluster of Redstone and Jupier missiles, but it looks totally different.
The best way to go about building a clean-sheet HLLV is to mate existing engines with new tankage. The rocket should be designed around the available engines, not vice-versa.
I believe that an all-new modular rocket is the best way to attempt a clean-sheet HLLV. Hypothetically, it would resemble a beefier Delta IV or Atlas V that could launch 20+ MT in its single-core version or 100+ MT in a triple-core form.
The reason for this is economics. An HLLV may not make economic sense. But if it can be built from components used in commercially-available (and commercially-successful) rockets, the costs can be shared with an economically-viable vehicle.
It's possible that SDV could actually make use of this modular approach. The SRB could be the first stage for a smaller rocket, with the SDV and SRB-based rocket sharing a common LH2 upper stage. If the ET engines are put on the bottom of the tank, the tank could be used without SRBs to launch lighter payloads.
I do believe it would be a mistake to use current boosters to make an HLLV. The rocket would eventually become an entirely different animal, and would require new launch facilities.
The RD-180 is also said to be reusable, but only for about four flights. This is still better than the RS-68, which ablates and cannot be reused. The industry has been building reusable rocket engines since the days of the X-15 and NF-104. The difficult part will be re-flying the engine with a minimum of inspection between flights. If we had to pull the jets off an airliner and swap them out after every flight, the airlines would be out of business.
My bad on messing up the details. Still, it's important to know if the RD-0120 manufacturer has started producing mundane consumer and medical products like Energia has. I haven't seriously considered the RD-0120 before, but I will compare it with the SSME and RS-68 in my SDV paper study.
RS-68 is cheaper; I don't know the cost of RD-0120 but I imagine they're also cheaper. They're expendable and Russia tends to make good stuff at a lower price.
I assume that RD-0120 is even cheaper than RS-68 because the labor and certain raw materials (like titanium) are cheaper in Russia.
The two factors which would make the RD-0120 more expensive are the cooling jacket (which adds complexity, versus the simple ablative RS-68) and the cost of resuming production and refurbishing the tooling and assembly lines. I have heard that the Energia plant is now used to make items like syringes and baby strollers. They'll have to either find a new plant or kick the strollers and needles out. Most likely, they'd sign an agreement with Pratt & Whitney to build the engines in the US (which negates the inherent cost advantages of doing business in Russia.)
Every plan to recover liquid fuel rockets from the ocean has involved a retractable metal shield that would deploy over the engine bells. This would add some weight and some complexity to the recoverable engine pod, but it's not an insurmountable challenge.
IF they build an SDV, I was thinking about the idea of recovering the avionics. It's been said that over 90% of the cost of a military aircraft is its avionics. While a rocket has higher non-avionics costs and less sophisticated avionics than combat aircraft do, the cost benefits of recovering the avionics might be justified.
I have reservations about a regenerative "RS-68R." The RS-68, while heavier than the SSME, can get away with a lower parts count because it uses an ablative nozzle instead of a regeneratively-cooled one. This is consistent with the "big dumb booster" philosophy of sacrificing performance and taking on more weight in exchange for simplicity and lower cost.
A regeneratively-cooled RS-68 would be a very different animal than the original RS-68. It would have about 2x the parts and would probably be more expensive by a similar factor. If you plan on building a lot of these engines and throwing them away on expendable rokets, I would rather go with the lower performance and find a way to lighten my payload instead.
The Request For Proposals came out today. I think GCNRevenger will be vindicated by a detail made clear in the RFP: the Earth Departure Stage will be used for lunar orbit insertion. The delta-V requirement on the CEV will be lower, enabling the 20 tonne launch weight.
I totally agree that the engineers of the time (late 60's, early 70's) had unrealistic expectations for how difficult it would be to build and operate a reusable spaceship. While I think the Faget DC-3 would have been safer and cheaper than the shuttle, I'm certain that the flight rate would have been similar. Without building the X-20 Dyna-Soar, there's no way we could have ever known how difficult it would be to inspect, repair and turn around a used spaceship.
Assuming that CEV will be expendable, future RLV's should take an incremental aproach. An X-20 style vehicle is a must for demonstrating RLV technologies. The next step is an HL-20 sized vehicle launched by reusable boosters. After that we might be ready for a shuttle-sized TSTO or perhaps even an SSTO.
My concern with these HTOL spaceplane systems is the separation of the orbiter from the mothership. While it might be possible to build a Mach-6 mothership, the ability to separate the orbiter for staging appears sporty at best. The closest we've ever come towards trying was the D-21 launched by the Blackbird. The D-21 was launched at Mach 2, and even still there was an instance where the D-21's control surfaces failed and the drone crashed into its mothership.
I don't know if mounting the orbiter on top of the mothership or below it will make a big difference in ensuring a safe separation. Perhaps the best approach is to accelerate to Mach 3 with turbojets, get above Mach 5 with ramjets, then ignite a rocket engine and enter a steep climb. The orbiter would be released just before apogee, so it's in the proper attitude whe its own engines ignite.
TSTO shouldn't have been too hard to pull off, as long as the payload and cross-range requirements were reasonable. To this end, the Faget-designed DC-3 would have been a perfectly good space shuttle.
As soon as the Air Force and NASA were forced to cooperate, the shuttle was doomed. Placing a 20-ton spy sat in polar orbit and coming back to base one orbit later is a challenging task that necessitated the shuttle configuration we all recognize today. The shame of it all is that the shuttle was never used for this mission.
SRB's aren't necessarily bad--if NASA had gone with monolithic solids instead of segmented ones. Aerojet could have built these monolithic boosters from its plant near Cape Canaveral, but NASA felt this was unfair because other potential contractors didn't have the facilities near the cape to build large solid motors.
Dook, I'd suggest you pick up a book like "Fundamentals of Aerodynamics" by John D. Anderson for the answers to these complicated questions that are too lengthy to be answered on this forum.
If you want a short answer, why don't you look at the specs for aircraft with similar dimensions and performance profiles? There aren't too many planes like that out there, but the SR-71 and B-58 should at least steer you in the right direction. Also keep in mind that thrust is almost directly proportional to atmospheric density, so get the standard atmospheric tables out and be prepared to adjust your thrust levels for that altitude.
How do you determine the maximum altitude an aircraft can fly at?
I know weight vs thrust are the main factors, then wing surface area, and to some degree the wings shape.
It's complicated, but it boils down to the balance of forces. As altitude changes, the air density changes. This has the effect of decreasing your thrust, drag, and lift. Of the four basic forces acting on the aircraft, the only one that doesn't change is the force of weight.
For your maximum altitude, your lift force has to match the weight of the aircraft. Then the engine thrust has to match the drag force.
There are many things you can do to increase the value of the lift force. The 2D lift coefficient is determined by your airfoil cross section. The 3D lift coefficient takes the 2D coefficient into account but also has the wing's planform shape as a variable. Wings with high aspect ratio (like sailplane wings) create higher lift, while swept and delta wings create less lift. Wing area is also important.
With Columbia they knew there was a problem with foam hitting the orbiter. This happened on the first launch (STS-1 April 12, 1981) and they used a military telescope in Hawaii to determine which tiles were missing. The military got upset when NASA released the pictures. This time they knew there was a problem again, but a manager chose not to ask the military to use the same telescope again. His gamble lost.
STS-1 lost tiles because of a pressure wave at ignition rather than a debris strike. I'm also skeptical about the military telescope story (but then again, I was not around to witness STS-1.)
The reason NASA gave for not getting better imagery of Columbia is one of resolution. An attempt to use spy sats to examine potential damage during STS-95 proved to be useless. NASA managers had no reason to expect any better if they asked the NRO to point its sats on Columbia.
The point I was trying to make about the X-20 is that it was supposed to be both manned and reusable (unlike the BOR-4 and BOR-5.) X-20 would have taught us that launching, recovering, and turning around a manned spacecraft would be more difficult than we believed at the time. The shuttle never achieved a launch rate greater than nine flights per year, although NASA had hoped for over twenty per year when the program started.
In regards to my conviction that a shuttle accident was inevitable in 1986, I suggest you read books like "The Challenger Launch Decision" or talk to the shuttle personnel who worked during that period. Challenger was the product of the NASA culture at the time, which put its schedule ahead of the well-being of the astronauts. Look at STS-61C, launched just 16 days before Challenger (which was almost launched after somebody started to accidentally drain the LOX tank,) or STS-51F in 1985 (where a main engine shut down early after a sensor problem, and the mission was aborted to a lower orbit.)
Regardless of what technology is available, accidents will happen when you insist on pushing too hard and ignoring the concerns of your engineers.
My big question is what the astronauts will do if Discovery's TPS is damaged. Will they wait for the rescue shuttle, or will they risk it with the repair kits? I get the impression that the astronauts don't put a lot of faith in the repair methods.
If NASA could fully automate the orbiter, the potential exists for rescuing the crew and saving the orbiter at the same time. That way, the astronauts could patch the damage and fly it back unmanned in case the patch isn't good enough. The astronauts, better safe than sorry, stay holed up in the ISS until their rescue shuttle arrives.