Cross-range was more critical back before we perfected pin-point re-entries. Today, cross-range capability matters little.
Also, you can make the 2nd stage *any* shape.
Posted on 03/05/2006 7:23:35 PM PST by anymouse
> Lifting capability has no meaningful bearing on recovering a spacecraft.
Sigh. Once again you demonstrate a serious lack of understanding of both military requirements *and* orbital dynamics. Crossrange is *extremely* important for applications such as this. Until you understand that, you will not understand basic launch vehicle/recovery design.
> capsules can be re-used if desired.
True but irrelevant, since you can't make a practical, capsule-shaped, ballistically-recovered low L/D complete second stage. You can only make the *payload* a capsule.
Cross-range was more critical back before we perfected pin-point re-entries. Today, cross-range capability matters little.
Also, you can make the 2nd stage *any* shape.
> Cross-range was more critical back before we perfected pin-point re-entries. Today, cross-range capability matters little.
Ah.... no.
In case anyone *else* is playing along and cares to learn a little something, here's the deal: When you have a spacecraft that is meant to be "operational" in the same way that a jet fighter is, that means that the craft must land someplace where it's not a big deal. Not the ocean, not some desert somewehre, but on a runway or a base, so that it can be scooped up, fixed up, fueled up and sent back out as soon as possible with as little trouble as possible.
The problem here is basic orbital dynamics. Unless you launch from the north or the south poles (or are extravageantly lavish in on-orbit plane change fuel expendature, which so far is beyond the state of the art)... you will *not* be anwhere near your launch site when you've completed your first orbit. The problem is that your first orbit will take about ninety minutes. But in that time, the Earth will have rotated, and your launch site won't be under you anymore. Worse, if your target is high-priority and fast response (say, we found that Iran was fueling up their ICBMs and were about to launch), then you launch from where you can as soon as you can... and that means that there mayb *not* be a decent landing site *anywhere* near your re-entry site. Re-entry could put you a thousand miles from a decent landing site. So, the only two ways to deal with this are to either ditch the spacecraft (there goes a billion dollars plus) or make sure your spacecraft has at least *minimal* cross range capability. Ballistic capsules have very little. Lifting bodies can have many hundreds of miles. Winged vehicles are best, but trade poorly compared to much simpler lifting bodies.
The reason why the Genesis and Stardust capsules were able to land on a dime is because they spent *months* approaching Earth. A very slight cahnge in velocity meant hours or days difference on re-entry timing. It makes things easy. But once-around craft, or craft meant to intercept satellites, do *not* have that opportunity. They have to get up and get down ASAP, and that means they need crossrange.
No. TSTO craft do need to get up ASAP, but they don't have to come *down* ASAP.
And with our current re-entry technology, a single extra orbit (in many cases, just one orbit at all) means that a ballistic recovery can be as precise as were the glide landings of old.
> TSTO craft do need to get up ASAP, but they don't have to come *down* ASAP.
Hogwash. If you have a secret vehicle, you don;t keep it up for days on end when you don't need to... *especially* if you were stupid enough to make it a capsule configuration, just about the least-stealthy spacecraft shape possible.
> And with our current re-entry technology, a single extra orbit (in many cases, just one orbit at all) means that a ballistic recovery can be as precise as were the glide landings of old.
Oy vey. One extra orbit moves you even *further* away from a useful landing site. Yes, you can have a precise landing... but it'll be precisely in the middle fo the friggen' ocean or someoen's back yard... *not* at an airbase.
I gotta hand it to you, you're certainly impervious to facts and logic.
Our technology can descend at the appropriate place and at the appropriate time, as desired, from an orbit.
This means that a ballistic recovery can happen in Utah (e.g. the Stardust mission that you continuously misrepresent, and no doubt will misrepresent further in your inane and unending replies) or anywhere else, as needed.
Wings for such a craft are therefore *not* needed; a simple Apollo-era parachute system will suffice...your uneducated rants to the contrary notwithstanding.
I've cited American ballistic recovery efforts that have nailed their parachute landings; you've cited...well...nothing.
Your argument basically consists of attacking me and claiming that we can't do precisely what we've been doing publicly for years. You have no examples to support your baseless accusations, so you are left with criticizing me as your only, repeat, *only* option other than fleeing from a debate that you lost long ago.
Had you put as much effort into your aeronautical education as into this rant, you'd be taking a much different position...one that others in the field could actually find some level of agreement with, no doubt.
> Our technology can descend at the appropriate place and at the appropriate time, as desired, from an orbit.
No, *it* *can't*. You've been watching WAY too much Star Trek. Explain how a non-lifting ballistic capsule on a 15 degree inclination orbit can land in Utah. Or, in fact, anywhere in the continental United States. How soon can a non-lifting ballistic capsule currently 100 miles west of Los Angeles heading due south land within the continental United States? You've just launched your non-lifting ballistic capsule on a low-altitude mission to recon or bomb a target halway around the world. Oops, information just came in that the target is on the move, and will be fifty miles south of where you thought it would be. How do you adjust your course to still get over the target? Now that you've adjusted your course, where do you plan to land in your non-lifitng vehicle that is incapable of aerodyanmic maneuvering?
> This means that a ballistic recovery can happen in Utah
How would a ballistic capsule over, say, the middle east on a polar orbit, with 50 miles crossrange, launched *from* Utah on a polar orbit get *back* to Utah in anything less than half a dozen orbits???
And you conveniently keep forgetting the propulsion system for this capsule. Where is it? What happened to it?
> I've cited American ballistic recovery efforts that have nailed their parachute landings...
You cited *irrelevant* efforts. If you knew anything about orbital mechanics, you'd know why.
> Your argument basically consists of attacking me and claiming that we can't do precisely what we've been doing publicly for years.
What we've been doing publicly for years is landing the Space Shuttle where we want to, precisely because it has wings and a decent cross-range. And even then it can't land whenever the hell they might want to. You miss a wnindow, and you're screwed.
> You have no examples to support your baseless accusations,
What, you mean like the Space Shuttle? Buran? Pioneer Rocketplane? HYWARDS? Brass Bell? BoMi? RoBo? Dyna Soar? HGV? CAV? OSP? X-35? These are actually relevant to the discussion in a way that Stardust is not.
> Had you put as much effort into your aeronautical education as into this rant
Please. Is this your little way of announcing that you have no idea what the hell you're jabbering about?
Yes, I have an aeroSPACE degree (not aeronautical). I've spent the past decade working with ballistic trajectories and hypersonic gliding. What have you been doing? Your profile says you're a private pilot. OK, here's a little excercise for you: you're at 12,000 feet in an unpowered craft. The nearest safe landing spot is 15 miles away. What do you want to have... a lifting vehicle, or a capsule with a parachute? THIS is the arguement you keep losing.
Answer the simple excercises I pose here, if you care to have your opinion respected.
On August 18, 1960, Discoverer XIV was launched with a CORONA camera on board. The launch vehicle, satellite, and camera all performed flawlessly, and all 20 pounds of exposed film were successfully recovered in mid-air.
Yes, that's right. We caught a 40 pound bucket filled with 20 pounds of film in mid-air...in 1960!
Oh, my goodness. Who woulda thunk that the *wings* for the capsule recovery could be flown to meet the descending film capsule?!
What a shocker. A C-17 caught a ballistic recovery capsule in mid-air, parachute and all.
Oh, and there were 101 more such successful Corona film recovery missions after Discoverer XIV's success.
So you see, even with 1960 tech, the U.S. has been able to do ballistic recoveries wherever we please, sans wings.
>> A C-17 caught a ballistic recovery capsule in mid-air, parachute and all.
Don't you think a smaller aircraft would have been more appropriate? Also, in 1960 they must have been flying the C-17 prototype.
> We caught a 40 pound bucket filled with 20 pounds of film in mid-air...in 1960!
And what relevance does that have here? Once again, you failed to answer the question about the propulsion system. Where is it?
And you further embarass yourself with this gem: "A C-17 caught a ballistic recovery capsule in mid-air, parachute and all."
A C-17. In 1960. And you expect your opinion regarding advanced launch systems to be taken seriously?
> So you see, even with 1960 tech, the U.S. has been able to do ballistic recoveries wherever we please, sans wings.
*snort*
Hardly. These were multi-orbit vehicles, not once-arounds; maneuver capability was non-existent, and the recovered weight was *40* pounds. Where's the propulsion system? How many crew could you pack intoa 40-pound alotment So you see, even with 1960 tech, the U.S. has been able to do ballistic recoveries wherever we please, sans wings.?
Bah.
> Don't you think a smaller aircraft would have been more appropriate?
Keep in mind what came down: a tiny little capsule. These capsules stayed up for many orbits, which allowed program planers a wide range of optional re-entry and recovery zones. In wartime, neither of these aspects woudl be useful: instead of a tiny capsule, it would be an *entire* manned vehcile, including the propulsion system. Instead of 40 pounds, think something more like 20,000 pounds. Plus, in wartime, you can't stay up for days or weeks waiting for a re-entry window; you come down ASAP. The only way to make this work is with crossrange capability.
The relevance is that the Corona and Stardust missions landed ballistic capsules at precise locations in the U.S., just as I pointed out could be done and would be done with any fast-tracked TSTO system.
The needed propulsion systems primarily reside on the carrier aircraft for the initial launch phase, as well as in the capturing aircraft on the final stage of the descent phase.
By having a carrying and capturing aircraft for the spacecraft, the spacecraft itself has no need for its own wings. Thus, the designers can eliminate those wings to save weight (and drag, if desired).
But you are stuck in a world of thought where spacecraft have to have wings for re-entry; that line of thinking has been obsolete since August of 1960.
The TSTO described in the article for this thread need not have wings. Those looking for winged spacecraft will no doubt fail to recognize the actual Blackstar spacecraft...because that space capsule didn't have wings.
And the spacecraft itself doesn't need to have its own wings because we have carrier and capture aircraft (when needed) that *do* have wings.
> The relevance is that the Corona and Stardust missions landed ballistic capsules at precise locations in the U.S.,
Not relevant to this discussion, as the trajectories are of a wholly different class.
> The needed propulsion systems primarily reside on the carrier aircraft for the initial launch phase
OK, so you *do* want winged, hypersonic manned spaceplanes then? Drop your capsule from a C-17, and you'll go nowhere. You need to get your capsule to Mach 17 or better. But if your aircraft is so capable, why do you want a capsule? What does it buy you that the hypersonic aircraft doesn't? Waste of mass.
> But you are stuck in a world of thought where spacecraft have to have wings for re-entry
Incorrect. Only those which are to have military utility as operational vehicles.
> The TSTO described in the article for this thread need not have wings.
Correct. It's a lifting body. A good hypersonic L/D, capable of decent cross-range.
> No, wings or a lifting body add weight and complexity to the process...something that you
> would forego if you were in a hurry or on a budget...simply because you don't
> need to glide, you just need a parachute (which can land precisely where you want it).
>> Stardust capsule headed for Utah landing
>> Capsule parachutes back filled with with particles of comet dust
The Stardust capsule carried no passengers or crew, nor was the capsule expected to survive in flyable condition.
Capsule landings are hard landings. Capsules can't absorb impacts the way parachutists do. The Air Force spent considerable time and money experimenting with escape capsules, and the results were not promising.
The Russian Soyuz capsules have to use rocket engines to brake at the last minute before landing. It's not as simple as you imply. They land in a big vacant patch of Siberia and have helicopter search teams, because they cannot land precisely where they want.
If you're in a hurry or on a budget, you need to fly test missions, evaluate the results, and fly again, in quick succession. You need a robust landing system than can return the crew and equipment and flying condition. You can't afford to spend months building a new vehicle -- or weeks repairing one --after every landing, nor can you afford to lose crews just because a capsule crashes in a bad location.
We don't even like to use the drag chute on landing, because repacking it limits our time between sorties.
You must have missed that entire "Apollo" moonshot era...
> You must have missed that entire "Apollo" moonshot era...
No, I didn't. You must have missed the fact that Apollo made spaceflight so expensive that no one's been back to the Moon more than 30 years.
Each Apollo mission required a carrier battle group to locate and rescue the capsule after "splashdown." If you think that's cheap, I suggest you talk to the Navy.
No Apollo capsule was ever reused. A Gemini capsule was, but only after extensive refurbishment. The Apollo program cost as much as a small war. It does not support your claim that capsules are cheap and easy.
This story is obviously false, for several reasons, but the concept of a highly operable space vehicle is sound. Operational vehicles, when they are built, won't look like NASA circus stunts.
You've posted a series of inane and irrelevant comments that obviously have no bearing on the conversational points made in this thread.
If you have an agenda, speak it clearly. If you don't, then stay on topic. The cost of a carrier task force has no bearing on whether a film capsule can be recovered from space, for instance (even if the film bucket has no wings).
> If you have an agenda, speak it clearly. If you don't, then stay on topic. The cost
> of a carrier task force has no bearing on whether a film capsule can be recovered from
> space, for instance
My comments are on topic. We were not discussing whether it was possible to recover a film capsule from space.
We were discussing your view that capsules are somehow superior to controlled landing "if you were in a hurry or on a budget."
If you don't understand how recovery costs like carrier task forces run up a budget, you need to think again.
The fact that a film capsule was recovered from space does not prove that developing such recovery systems was fast or cheap. The Air Force spent a lot of time and money developing that system. The fact that it worked for 20-pound film capsules does not mean it will work for human beings.
The extensive history of aircraft development shows that the way to develop hardware quickly and cheaply is to fly early and fly often. That means controlled landing, so you can fly again the next day. Not crashing equipment in the desert or the ocean and spending weeks or months repairing it before the next flight.
Catching a film capsule in mid air as it parachutes back from re-entry *is* an example of controlled flight. That's Corona, U.S. technology from 1960.
Ditto for Stardust landing in Utah, U.S. technology from the 1990's.
Safe capsule recovery for humans was demonstrated on Gemini and Apollo missions, again, U.S. technology from the 1960's.
What do all of these things have in common? The space vehicles themselves had no wings. By dropping the wings, weight was saved during the critical ascent phase.
Thus, these four examples: Gemini, Apollo, Stardust, and Corona (102 successful mid-air film captures from orbit) point toward a Blackstar program that used space vehicles sans wings.
> Catching a film capsule in mid air as it parachutes back from re-entry *is* an example of controlled flight
Parachutes are at the mercy of the winds. The only controlled flight is on the part of the aircraft doing the "catching."
You also overlook the obvious difference between a 20-pound film cannister and a several-thousand-pound crew capsule.
> Ditto for Stardust landing in Utah, U.S. technology from the 1990's.
Ditto for every airplane crash -- calling a crash landing "controlled" does not make it controlled.
> Safe capsule recovery for humans was demonstrated on Gemini and Apollo missions
> What do all of these things have in common?
All of them were extremely expensive -- many millions of dollars per flight.
All of them took a lot time to develop and test.
None support your claim that capsules are cheap or quick to develop.
None could sustain any significant flight rate.
All were unreliable and dangerous, with failure rates thousands of times higher than aircraft operations.
> Thus, these four examples: Gemini, Apollo, Stardust, and Corona (102 successful mid-air film captures from orbit)
> point toward a Blackstar program that used space vehicles sans wings.
They point to nothing of the sort. "Blackstar" is fiction.
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