If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#151
|
|||
|
|||
Add a global communications system, smaller faster computers,
new construction material, medical technology, fuel cells, and scands of other details. But most of all? A sense of assurance that, working together, we can do anything. "Dream not small dreams, for they have not the power to fire men's souls" Johann Wolfgang von Goethe |
#153
|
|||
|
|||
ChuckSlusarczyk wrote in message ...
In article , pacplyer says... Yes, I believe you are correct Rich. Was listening to the 104.9 disk jockey that was claiming this was the ten million dollar x-prize attempt. But I believe you are correct on the plan. But if I was Burt: I would have stuck in a couple of sand-filled mannequins and claimed this was attempt #1 since it is so dangerous. pac If he did that he probably would not have made the altitude required. They barely made it as it was due to a minor mechanical glitch.This flight proved the systems and what adjustments must be made. JMHO See ya Chuck Yes I think you're right Chuck. You've probably done a little testing along those lines in new ships, right? You test pilots are brave Mo Fo's. Us cowardly cargo dogs just want to get the mission done in as few trips as possible. Same thing with the Casinos. Reduce the wife's trips to Vegas and you improve the odds of buying yourself a new Hawk someday.... ;-) pac |
#154
|
|||
|
|||
anonymous coward wrote in message e...
On Fri, 25 Jun 2004 04:14:25 -0700, ChuckSlusarczyk wrote: In article , pacplyer says... Yes, I believe you are correct Rich. Was listening to the 104.9 disk jockey that was claiming this was the ten million dollar x-prize attempt. But I believe you are correct on the plan. But if I was Burt: I would have stuck in a couple of sand-filled mannequins and claimed this was attempt #1 since it is so dangerous. pac If he did that he probably would not have made the altitude required. They barely made it as it was due to a minor mechanical glitch.This flight proved the systems and what adjustments must be made. JMHO Has anybody made a guess as to how high spaceship 1 will be able to go when it has passengers + a full rocket engine? AC I would think it is a matter of simply increasing the fuel load. The burn was billed for 90 seconds, but they only got seventy some seconds before burnout. Greater Burn time = higher Altitude. The designed gross weight should be able to attain 62.5 miles. But ask Dr. "A"-o.k. Evil ). He claims to have secret hardware on the moon and mars! ;^D ROTFOL! pacplyer |
#155
|
|||
|
|||
wrote in message . ..
On 25 Jun 2004 19:14:42 GMT, (B2431) wrote: Remember the "space plane" NASA was working on that would get you from NYC to Tokyo in a couple of hours? I think a spin off might just be the commuter equivillent between Lost Angeles, Peoples' Republic of California and NYC, NY. I know it took about an hour just to get to launch altitude, but SS1 is essentially a proof of concept. Maybe Rutan has a 200 passenger version in the back of his mind. Dan, U.S. Air Force, retired I can remember two things that the public got their hands on that were developed for the Space Program: Tang and a pen that works upside down. I recall someone mentioning that the Russians also realised that a normal pen would not work in outer space, they gave their astronauts a pencil.... Corky Scott Don't forget the little thing you're typing on right now or the thing you GPS around with; the mobile computer (VLSI, which you are using now) was developed specifically for the Space Program (Guidance and Nav.) Without that, your entire house would be full of electronic componants right now (or more likely, you'd send letters to us with your Royal (pain) typerwriter and carbon paper.) pacplyer |
#156
|
|||
|
|||
anonymous coward wrote in message e...
On Fri, 25 Jun 2004 04:14:25 -0700, ChuckSlusarczyk wrote: In article , pacplyer says... Yes, I believe you are correct Rich. Was listening to the 104.9 disk jockey that was claiming this was the ten million dollar x-prize attempt. But I believe you are correct on the plan. But if I was Burt: I would have stuck in a couple of sand-filled mannequins and claimed this was attempt #1 since it is so dangerous. pac If he did that he probably would not have made the altitude required. They barely made it as it was due to a minor mechanical glitch.This flight proved the systems and what adjustments must be made. JMHO Has anybody made a guess as to how high spaceship 1 will be able to go when it has passengers + a full rocket engine? AC I would think it is a matter of simply increasing the fuel load. The burn was billed for 90 seconds, but they only got seventy some seconds before burnout. Greater Burn time = higher Altitude. The designed gross weight should be able to attain 62.5 miles. But ask Dr. "A"-o.k. Evil ). He claims to have secret hardware on the moon and mars! ;^D ROTFOL! pacplyer |
#157
|
|||
|
|||
In article , pacplyer says...
Yes I think you're right Chuck. You've probably done a little testing along those lines in new ships, right? You test pilots are brave Mo Fo's. Hi Pac While it true I've personally tested every Hang glider I ever designed and did all the test flying for all my reduction drive testing I am not a "real" test pilot nor do I claim to be. The "real" test pilots are the brave MO FO's not me. I was just testing my designs. There are some people who like to be called "test pilot" because they went to a 1 week course but that's not me. "Real" test pilot's all have a wheel barrow to transport their gonads to the airplane and my hats off to those guys:-) Us cowardly cargo dogs just want to get the mission done in as few trips as possible. Same thing with the Casinos. Reduce the wife's trips to Vegas and you improve the odds of buying yourself a new Hawk someday.... ;-) I went to Vegas once for a UL convention and lost $25.00 to the slot machines and that cured me from gambling forever LOL!! See ya Chuck (test pile it ) S |
#158
|
|||
|
|||
On Wed, 23 Jun 2004 23:08:49 +0000, Richard Lamb wrote:
Steve VanSickle wrote: Yes, it is more difficult. Yes, much hotter, much more energy. But I have heard many people claim that the "shuttlecock" method Burt developed "won't work" from orbit, and no one says *why*. If shuttle wings can be protected (most of the time) from the heat, why can't Burt's wings? That seems like a reasonable question. Wish I knew a reasonable answer. Taking a not so scientific wild assed guess(?) it might have to do with the amount of area exposed to the plasma stream. On the Orbiter, only (mostly?) the leading edges are exposed to that level of heating. Actually, the Space Shuttle comes into the atmosphere at about 30 deg angle of attack, so spread the heat load over the whole bottom of the vehicle. http://www.nasa.gov/audience/forstudents/9-12/features/F_Aeronautics_of_Space_Shuttle.html -- Kevin Horton RV-8 (finishing kit) Ottawa, Canada http://go.phpwebhosting.com/~khorton/rv8/ e-mail: khorton02(_at_)rogers(_dot_)com |
#159
|
|||
|
|||
Thinking about all the postings I've made on this subject in the past week,
I realize that I've never really spelled out the difficulties involved in evolving SpaceShipOne into a vehicle capable of orbit. Several of us have mentioned the difference in the speed required for Monday's sub-orbital vs an orbital mission, and the problems of re-entry, but those without a space or physics background may not grasp the impact of some of the factors so casually thrown about. This is an attempt to describe some of the engineering problems that must be faced, and some typical solutions, when evolving a Scaled SpaceShipOne (SS1) class of sub-orbital homebuilt spacecraft into one capable of at least one orbit of the Earth. REVERSE ENGINEERING SS1 The first thing we have to do is figure out the characteristics of the vehicle we're starting with. Scaled hasn't released many of the technical details needed for an in-depth analysis...after all, it *is* a private rocket, and not a government one where the information is public domain. Basically, we need two numbers to start with: The launch weight and the rocket motor's Specific Impulse, or "ISP". How heavy is SS1? According to Scaled's info sheet, the White Knight can carry and launch payloads up to 8,000 pounds. Is 8,000 pounds the maximum gross weight of SS1? I'd like to think that Rutan carries some margin...considerable margin, in fact. Lets assume the max launch weight of SS1 is 6000 pounds; a 25% margin for the White Knight. How much of that is fuel? There are two ways of working this. First, we can take the known performance parameters (e.g., at least 62 NM altitude on a ballistic trajectory, with a launch at 8 NM) and compute how much propellant is required. Or...we can eyeball the photos and drawings on the Scaled web pages, estimate the capacity of the fuel tanks, and compute the fuel weight from that. Let's look at the second method. SS1 uses a hybrid rocket motor, with a combination of liquid oxidizer (carried in a tank) and solid propellant (cast into motor housing). The external dimension of the oxidizer tank is the same as the fuselage (five feet) and about 75% long as its diameter. It's listed as liquid nitrous oxide, which, converting some data found online, has a density of about 76 lbs per cubic foot (which seems high, to me). Given insulation, wall thicknesses, etc. for the tank, I'm guessing SS1 can carry about 2500 lbs of oxidizer. The fuel is apparently cast into the motor housing, which, eyeballing, is about 1.5 feet in diameter and six feet long. With wall thicknesses, etc, and using the density of "normal" solid fuel (which admittedly could be quite different from the rubber-based fuel SS1 uses), I get a fuel weight of 650 lbs. Total propellant load, then, is about 3150 lbs, leaving a no-fuel weight of 2850 lbs. Subtract another 510 pounds for three FAA-standard commonauts aboard, we get an SS1 empty weight of around 2340 pounds. Making the calculation the OTHER way (by mission parameters) gets a quite-different answer... needing only 1500 pounds of propellant, with a 6000-pound launch weight. This gives an empty weight of about 4000 pounds; a bit closer to my eyeball engineering estimate. But let's use the lighter weight...and the larger propellant load. The second parameter is the Specific Impulse ("ISP") of the motor. The ISP is a measure of how much ooomppph a rocket has; it is defined as the length of time (in seconds) a motor can produce one pound of thrust from one pound of fuel. ISPs can range from a few tens to in the thousands. But the very high numbers are the provinces of electrical propulsion systems that produce a few micropounds of thrust. LOX/Hydrogen comes in about the mid-300s, the LOX-JP4 yields around 250 seconds, and typical solids are a tad less than 300. What to use for Scaled's hybrid system? My personal guess is in the 250 range, but let's use 300 seconds so we don't short-change the hybrid system. HEADING FOR ORBIT So: We're assuming SS1, empty with three commonauts aboard, weighs 2850 pounds. The engine has an ISP of 300 seconds, and the stock SS1 carries 3150 pounds of fuel. We'll say the White Knight launches at eight nautical miles at a speed of 700 feet per second (fps) horizontal velocity. With the wings, SS1 can convert that to vertical velocity. Back from my distance past, I remember that the characteristic velocity for Low Earth Orbit (LEO) is about 27,000 fps. That includes drag makeup from the lower atmosphere, which White Knight takes care of by hauling SS1 so high. For simplicity's sake, let's assume that SS1 has to just accelerate to the orbital velocity required for a 100 NM orbit...about 25,500 FPS. Actual increase in speed (Delta-V, or "DV") after we factor in White Knight is about 24,800. I'll use a flat 24,000 FPS in case I've been too conservative...but remember, this speed is the DV needed to not only orbit at 100 NM, but to climb to that altitude as well. (For those non-US readers, a nautical mile is about 1.8 KM.) How much fuel will we need? The equation is: Fuel = Burnout mass * e^(dv/(isp *g)) - Burnout Mass Burnout Mass: 2840 lbs DV: 24,000 fps ISP: 300 sec G: 32 f/s^2 How much fuel does SS1 need to go orbital? About 31,460 pounds...almost ten times more than its current capacity. FILL 'ER UP, RON OK, how we gonna carry that much fuel? Internal loading is out, of course, if we're keeping the basic SS1 design. The obvious answer is a strap-on external tank, like the Shuttle uses. But...remember, SS1 uses a *hybrid* rocket, with cast fuel. The external tank could be used for the liquid nitrous oxide oxidizer, but the fuel itself is solid. An external tank could be used for the oxidizer, but we'd still need to load about 5,000 pounds into the motor casting itself...which, in no way, would fit inside the SS1's shell. If we're keeping the basic SS1 vehicle, there are only two solutions: Strap-ons (like the shuttle SRMs) or adding a stage (or stages) *behind* SS1 (like Saturn). Strap ons...well, they're going to increase drag immensely. SS1 is only five feet in diameter, and for the amount of fuel they'll have to carry, I can't see the strap-ons being any less than that. Even with two of them (ignoring the needed length for a moment) this vehicle is getting incredibly blunt. So...the classic staged approach seems the only answer. One or two stages behind SS1, probably a bit wider than the Space Vehicle itself. CARRYING THE FIRE Which gets us back to White Knight. It's got an 8,000-pound carrying capacity, and SS1 and its launch stages are probably well over 40,000 pounds. To quote Roy Schieder: "We're going to need a bigger boat!" Will White Knight scale up that far? And what about the extra length of the initial launch stages? Plus, this long rocket will have to be carried *horizontally*, and would have to be designed to withstand landing loads as well, in case a launch is aborted. Back in the early 90s, Orbital Sciences Corporation developed an air-launched space booster called "Pegasus." It was carried aloft on the same B-52 that carried the X-15, and launched exactly the same way. It carried about 600 pounds to LEO, and the payload could be up to ~4 feet in diameter and ~7 feet long. It's really rather clever, three off-the-shelf solid rocket motors stacked in conventional stages, with a wing atop the first stage and a conventional-style aircraft tail. Life being what it is, customers immediately wanted more performance. Orbital came up with the Pegasus XL, which lengthened the first stage rocket. It was too big for the B-52, so Orbital converted an L-1011 to carry the XL. But customers *still* wanted more. Orbital looked at the Pegasus design...then they ripped the wing and tail off, added yet another solid motor to the stack, and ended up with the ground-launched "Taurus." I think we'll end up with ground-launch for our orbital SS1 evolution. Fortunately, Rutan's operation at Mojave isn't all that far from the launch facility at Vandenberg Air Force Base (VAFB). White Knight could be used for carrying components to VAFB. Scaled would have to design the appropriate gantries to assemble the launch vehicle on the pad, but that's just ordinary engineering. Several companies already produce small launch vehicles that require only quite basic pad services (A trailer, a "milkstool", a concrete pad, and a cherry-picker, in one case). UP SHIP! OK, we've got the commonauts on board, the range is clear, and the countdown has reached zero. OrbitalOne soars into the California skies. Since it's operating from VAFB, the flight path has conform to Vandenberg range safety limitations. Conventional launch vehicles drop stages behind them, and the Air Force insists they not overfly any population centers. Since there are population centers the entire western coast of the US, Mexico, Latin America, and South America, this really restricts the inclination of the orbits that you launch into. The "inclination" of the orbit is the orbit's "tilt" relative to the equator. The inclination also indicates the maximum latitude that the spacecraft reaches during its orbit. A 15-degree inclined orbit, for instance, would mean the spacecraft never crosses over the United States, mid- or southern-Australia, or Europe. Basically, OrbitOne is going to have to launch into a polar orbit...about a 90-degree inclination. From the Space Tourist's point of view, this is great, as the spacecraft will fly over the poles as well. The orbit itself isn't much of a bother, though performance is actually less since you don't pick up ~600 miles per hour of boost due to the Earth's spin. The stages drop behind. Finally, OrbitOne cranks up its trusty hybrid rocket motor to give it the last bit of push into space. ON ORBIT OrbitOne flies down the open reaches of the South Pacific, crosses over Antarctica, then heads northward again. It reaches apogee as it passes over Mozambique. (Quick primer: apogee is the highest point of an Earth orbit, perigee is the lowest...to remember which is which, think "perigee is perilous.") If OrbitOne intends to perform more than a single orbit, it will have to perform a short "circularization" burn here. Without an apogee burn, it'll reenter back on the other side of the Earth, where the launch point had been. "Had been"? Because in the 90 minutes the orbit will take, the Earth's rotation will have taken the coast of California about 1300 miles to the East. OrbitOne is destined to re-enter about 600 miles East of Hawaii, unless it performs a circularization burn at Apogee or lands in Alaska (for which it'll probably have to perform some sort of deorbit burn, to bring it in that much earlier than normal orbit physics). Unlike launch, though, the apogee burn doesn't have to be very strong...just a hundred FPS or so. The question is, what does it perform the burn with? Will its hybrid rocket have restart capability? Normal solid rockets are neither throttleable or stoppable. They burn until all the fuel is consumed, just like a bottle rocket. Since SS1's hybrid rocket has a liquid oxidizer, we can anticipate that they can, at least, turn off the oxidizer and shut down the rocket (unless the solid fuel contains just enough oxygen in it to keep a low flame going in a vacuum). But...will it really support a restart? The solid fuel actually burns away inside the motor casing as the hybrid runs. You can't just fire the same igniter...it'd be like dropping a match into the burned-out remains of a campfire. You have to strike the fire where tinder (intact fuel) still exists. And... shutting down the oxidizer as the hybrid is running might coat the fuel with incomplete combustion products, inhibiting a start. They'll prove or disprove this during Earth testing, of course, but we really may want to assume that the Hybrid won't really be suited as a circularization motor. Which means we have to have another propulsion system, one capable of zero-G restarts. It probably doesn't make sense to include both the hybrid and the new system, so we'll chuck the hybrid and use a restartable liquid-fueled system for both initial orbit insertion and circularization. After the circularization burn, OrbitOne flies over Saudi Arabia, the Caspian Sea, and central Russia. On the next orbit, the commonauts will view Central Africa, Italy, Greece, Finland, and Sweden, The pass after *that*, it's western Africa, Portugal, Spain, and the UK. OrbitOne will probably want to talk to ground control during this. SS1 used aircraft VHF, but that's line of sight and won't work for OrbitOne. The early US manned missions used low-inclination orbits, which allowed the US to sprinkle a few ground stations along the equator and get good comm coverage all through the orbits. But they're no help to OrbitOne's polar orbit The Shuttle and the Space Station use NASA's on-orbit Tracking and Data Relay System (TDRS) satellites. TDRS has plenty of excess capacity, and Scaled can probably lease bandwidth. I believe TDRS uses S-band, so not much of an antenna will be required...though you'll have to put several over the exterior of the spacecraft to maintain coverage no matter what the attitude. SpaceShipOne used a compressed-air system for attitude control. IIRC, they used one quarter of their total system capacity for Monday's flight lasting just a few minutes. Obviously, a *lot* more is going to be required on OrbitOne. This is a tourist flight, and the paying customers will want the pilot to rotate and pitch and yaw the spacecraft to give people the best view out the window. Then again, maybe they won't. Have you ever noticed, that when the Space Shuttle takes off on a mission to the Space Station, that it doesn't actually rendezvous for two days? That's not the time it takes to get there...that's time to allow the crew to get over "Space Adaptation Syndrome" (SAS), a nice NASA term for the motion sickness brought on by microgravity (My favorite term was coined by SF author Alan Steele: "Star Whoops"). About half the people exposed experience it to some degree, and there's no real way to tell who is susceptible. Watch the videos from space, someone who keeps their upper body, neck, and head stiff is probably suffering from it. OrbitOne will undoubtedly carry zero-gee barf bags, and Scaled will no doubt maintain the appropriate discretion to NOT reveal whom of its millionaire passengers spent their entire orbital time doing power-yawns into a sack.. And if OrbitOne performs the circularization delta-V, they'll have plenty of time to practice: If the ship does NOT land in Alaska prior to completion of the first orbit, it does not travel over the US for another eight hours...and it'll take two more orbits (~3 hours) beyond that for a pass that'll let OrbitOne land back at Mojave. This problem would be alleviated by a launch from the East coast of the US, rather than from California. With a 40-degree inclination out of Cape Canaveral, OrbitOne will cross over Mojave at the end of the third orbit. Whether Burt will be willing to move his launch operation 3,000 miles away is a question. In any case, the design will have to include hours of life-support for the personnel onboard. Plus carry the batteries or other power generating equipment required for running it, and for powering all the other systems. Power limitations alone may prevent OrbitOne from flying more an a couple of 90-minute orbits. RE-ENTRY We've already had a lot of discussion relative to re-entry...that SpaceShipOne's ballistic flight at Mach 3 maximum doesn't compare to the amount of energy converted into heat as OrbitOne slows from Mach 25. I've already posted my worries about exposing a deployable structure (e.g. the shuttlecock mode) to the re-entry plasma, especially since it'll be necessary to retract it for landing. Also as far as I know, if the SS1 planform were re-used, it would be the first time a discontinuous shape has been used for re-entry. SS1 is a high-wing design, with a fuselage below. Everything else used in space presented a smooth, continuous surface to the re-entry plasma... the Shuttle presents its low-wing delta planform, and non-re-usable systems had curved re-entry shields. At a full-blown re-entry, I'm worried about turbulence in the plasma causing hot spots on the structure. The solutions? Well, like I previously posted, the glider planform could be eliminated and a capsule-type system with a heat shield could be used instead. Since OrbitOne will probably have to be ground launched, we've eliminated one reason for re-using SS1's glider planform. SS1's winged shape does allow cross-range capability like the Shuttle (use aerodynamics to offset your final trajectory from a mere ballistic one) but a disk shape can probably be tilted and steered as well. They experimented with Rogallo wings for Gemini; using one on a capsule-type OrbitOne would give some ability to pick the spot for landing. Soft touchdowns may be a problem, though...the Russians actually have solid rockets on their capsule that fire just before touchdown to reduce the shock. Or...heck, combine the approaches. Since OrbitOne doesn't have to "Fly" during launch, add a heat shield to the design. Stick the spacecraft on something form-fitting with the bottom shaped like a snowboard (Kowabunga, dude!), with explosive bolts, etc. to eject it when OrbitOne has shed all the re-entry heat. This is the system used in Mercury (though I believe the shield was actually retained). But then...we get into the problems involved with object release at high speeds. You'd *really* want to reassure yourself that the shield won't flip over and belt you on the way past. Whichever solution you like, don't forget weight. Our 3,000-pound spacecraft needed ten times its weight in fuel to launch. Every pound that your re-entry shielding or deceleration system adds will require at least ten more pounds of propellant at launch. And that includes the additional communications gear, the new engine, the life support systems, and batteries that we've added since my initial determination of propellant requirements. Personally, if Rutan does go orbital, I think we'll see a whole new shape. Probably a large lifting body. Well, that was fun... but it's a nice day outside, and I've already killed two hours of it at the computer. Time to go fly WoodChipOne! :-) Ron Wanttaja |
#160
|
|||
|
|||
Ron Wanttaja wrote:
Thinking about all the postings I've made on this subject in the past week, I realize that I've never really spelled out the difficulties involved in evolving SpaceShipOne into a vehicle capable of orbit. Several of us have mentioned the difference in the speed required for Monday's sub-orbital vs an orbital mission, and the problems of re-entry, but those without a space or physics background may not grasp the impact of some of the factors so casually thrown about. This is an attempt to describe some of the engineering problems that must be faced, and some typical solutions, when evolving a Scaled SpaceShipOne (SS1) class of sub-orbital homebuilt spacecraft into one capable of at least one orbit of the Earth. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Spaceship 1 hits 212,000 feet!!!!!! | BlakeleyTB | Home Built | 10 | May 20th 04 10:12 PM |