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Space Forum / Space Flight / March 2006National Aerospace Plane (X-30) announced 20 years ago
the NASP ~ National Aerospace Plane ~ X-30 which Ronald Reagan called " a new Orient Express" was announced 20 years ago this week during the State Of The Union address Feb 4, 1986. the NASP would've been a single stage to orbit space plane capable of taking off from conventional airport runways - accellerating to supersonic, hypersonic and orbital speeds using a combination of at least three propulsion systems (maybe 4 or 5 systems) that included turbojets, ramjets, scramjets and possibly rockets. It would have to sustain temps of over 1600 degrees over the surface of the airframe and upto 5000 degrees on the outer control surfaces. NASP would be a replacement & supplament for the space shuttle, spy aircraft (NASP was even more advanced than the fabled Aurora-based hypersonic spyplane(s), subsonic and supersonic commercial airliners and military bombers. NASP of course never made it - and all other hypersonic efforts, and SSTO and hypersonic efforts (i.e. X-33 ~ VenturStar and X-43 ~ Hyper-X ) have been lesser efforts that also failed NASP ~ National Aerospace Plane ~ X-30 ~ 'Orient Express' President Reagan's State of the Union 1986: "we are going forward with research on a new Orient Express that could, by the end of the next decade, take off from Dulles Airport, accelerate up to 25 times the speed of sound, attaining low Earth orbit or flying to Tokyo within two hours." NASP ~ National Aerospace Plane ~ X-30 ~ 'Orient Express' http://users.dbscorp.net/jmustain/x30.jpg http://www.materials.qmul.ac.uk/admissions/images/nasp.jpg http://pif.allolespace.com/invites_semaine/p_guillermier/images/nasp_x30.jpg http://www.fas.org/irp/mystery/nasp08.jpg http://www.fas.org/irp/mystery/x-30-AC92-0287-6_a.jpg http://ails.arc.nasa.gov/Images/Space/jpegs/AC86-0699-2_a.jpeg http://www.centennialofflight.gov/essay/Evolution_of_Technology/advanced_reentry /Tech20G5.jpg http://home.earthlink.net/~chadslattery/sitebuildercontent/sitebuilderpictures/x 30nasa.jpg http://history.nasa.gov/centtimeline/images/pict-1990_2.jpg concept video http://redstone.ae.gatech.edu/mm/Miscellaneous/NASP_promo.mov articles: http://fas.org/irp/mystery/nasp.htm http://www.astronautix.com/lvs/x30.htm http://www.geocities.com/CapeCanaveral/Launchpad/8574/X30.html > NASP would be a replacement & supplament for the space shuttle, spy > aircraft [quoted text clipped - 13 lines] > up to 25 times the speed of sound, attaining low Earth orbit or flying > to Tokyo within two hours." We are fully capable of doing the "orient express" today, and within 5 years. Today, we have lighter materials, more knowledge of the hypersonic environment, better computers, more heat resistant materials, and the new 'slush' hydrogen fuel tanks that can hold substantially more hydrogen. Today, a series of engine systems is unnecessary. SSMEs are a tried and proven engine that can do the job from start to finish. And, it won't cost a hundred billion dollars to do it. Maybe, 10 billion for a pair of the SSTOs. Why aren't we doing it? Ask the people in charge. tomcat > Today, we have lighter materials Somewhat, yes. > more knowledge of the hypersonic environment Somewhat, yes. > more heat resistant materials But we don't have much experience using those materials on hypersonic aircraft. The fact that a material has been developed doesn't mean engineers are happy using it for a given application. Qualification of a new material for a novel application can take more than five years. > and the new 'slush' hydrogen fuel tanks that can hold substantially more > hydrogen When were these "new" slush hydrogen tanks invented? As I recall, the slush hydrogen concept was around long before NASP and even figured in some early Shuttle concepts. > Why aren't we doing it? Ask the people in charge. I'm not in charge, but I could speculate. Aircraft that make sustained, atmospheric hypersonic flight just open a whole bunch of problems that aren't really worth dealing with. NASP was interesting, but why bother when there are easier alternatives? Mike Miller, Materials Engineer Assuming that you are asking "why not the NASP"..... What is about aircraft that fly in a atmosphere that make people that they are anygood for a space craft? Wings are not a good thing when there is no air or your going kinda fast, eps if your on a budget and don't need cross range. Non wing based SSTO or any other kind of xxTO will be cheaper and easier than a winged one. We are not flying... we'er orbiting. All IMHO of course (or IMO if you prefer) greg > Assuming that you are asking "why not the NASP"..... > [quoted text clipped - 9 lines] > > All IMHO of course (or IMO if you prefer) Wings use air to gain an advantage on gravity. Therefore, they can reach the airless void using less energy than a vertical tublular rocket. They also enable a spacecraft to 'fly' to a runway and land softly after deorbit. Wings are unnecessary for a spacecraft that is not designed for, and never intended for, planetary takeoff or planetfall. The proof that wings gain an advantage is that a bomber can reach 20,000 feet and stay there for the hours it takes to reach target and return on 1/10th of the thrust to weight ratio that a vertical tubular rocket requires just to slowly leave the launch pad. Air molecules are compressed by gravity and that compression gives lift with a properly designed airfoil. In short, you have to get from here to orbit and the best method is a winged or waverider vehicle. The airfoil vehicle, however, is more difficult to design than a vertical tubular rocket. So, NASA opted for a vertical tubular replacement for the Shuttle which will require a Capsule Parachute landing. Launching such a rocket in the year 2012 may prove embarrassing. Today, however, a waverider design shouldn't be all that difficult with the knowledge and materials base that exists in 2006. Titanium is plentiful and easily worked. The SSME (Space Shuttle Main Engine) has proven to be reliable. The tile problem has been solved (Don't tell NASA -- they haven't found out yet.). And, slush hydrogen tanks have solved the volume problem for hypergolic hydrogen/lox burners like the SSME. tomcat >> Assuming that you are asking "why not the NASP"..... >> [quoted text clipped - 13 lines] > reach the airless void using less energy than a vertical tublular > rocket. By definition wings cannot reach 'the airless void as they need air to function' <snip> > The proof that wings gain an advantage is that a bomber can reach > 20,000 feet and stay there for the hours it takes to reach target and > return on 1/10th of the thrust to weight ratio that a vertical tubular > rocket requires just to slowly leave the launch pad. Of course an ICBM gets to its target in minutes rather than hours which may be rather significant > Air molecules are compressed by gravity and that compression gives lift > with a properly designed airfoil. Oh dear you dont understand aerodynamics do you ? > In short, you have to get from here to orbit and the best method is a > winged or waverider vehicle. Wings dont work in vacuum remember ? The airfoil vehicle, however, is more > difficult to design than a vertical tubular rocket. So, NASA opted for > a vertical tubular replacement for the Shuttle which will require a [quoted text clipped - 3 lines] > Today, however, a waverider design shouldn't be all that difficult with > the knowledge and materials base that exists in 2006. Says someone who clearly has no clue. Keith > Wings use air to gain an advantage on gravity. Therefore, they can > reach the airless void using less energy than a vertical tublular > rocket. The goal isn't getting to orbit using the least energy -- it's getting to orbit the cheapest, safest way. The energy expended by a rocket is often inexpensive LOX and LH2. LOX is virtually free and LH2 is a very low % of operating costs. It makes no sense using a tremendously complicated, very expensive hypersonic airbreathing winged vehicle to save a few dollars of propellant. > The proof that wings gain an advantage is that a bomber can reach > 20,000 feet and stay there for the hours it takes to reach target and > return on 1/10th of the thrust to weight ratio that a vertical tubular > rocket requires just to slowly leave the launch pad. Actually this illustrates jet engines have much better specific fuel consumption than rockets. The B-52H TF33 jet engine has a specific fuel consumption of about 0.56 lb fuel per pound thrust per hr. The shuttle SSME consumes about 9.4 lb propellant per pound thrust per hr. If you replaced the B-52's jet engines with rockets, it couldn't fly for hrs, despite having wings. > In short, you have to get from here to orbit and the best method is a > winged or waverider vehicle. The best way is the cheapest most reliable way. Cheap means a combination of operating costs and development costs. Nobody gives you an award for getting to orbit the most romantic way, or the coolest way. > The airfoil vehicle, however, is more > difficult to design than a vertical tubular rocket. You've got that part right. A winged hypersonic airbreathing orbital launcher is so difficult nobody has figured out how to do it. > a waverider design shouldn't be all that difficult with > the knowledge and materials base that exists in 2006. Add about a hundred years to that and you're closer to correct. > And, slush hydrogen tanks have > solved the volume problem for hypergolic hydrogen/lox burners like the > SSME. Hydrogen/LOX engines are NOT hypergolic. -- Joe D. >>Assuming that you are asking "why not the NASP"..... >> [quoted text clipped - 16 lines] > not designed for, and never intended for, planetary takeoff or > planetfall. Wings do not allow for less energy to be used to orbit a craft- while they provide lift they do not provide any energy. In fact, since they also generate drag, a winged vehicle would almost certainly require more fuel to reach orbit, since the tubular design will have less drag to overcome. The wings are only useful during the descent and landing stage, where they allow you more options for a landing point, such as using a runway or some other point farther from the ground track of your orbit. > The proof that wings gain an advantage is that a bomber can reach > 20,000 feet and stay there for the hours it takes to reach target and > return on 1/10th of the thrust to weight ratio that a vertical tubular > rocket requires just to slowly leave the launch pad. This is totally irrelevant to wings being used on a spacecraft. While they do allow aircraft to fly with lower thrust to weight ratios, that has nothing to do with the fuel required to put a payload in orbit. Heck, in your example, most of that fuel is burned in cruise, during which you aren't even adding speed or altitude (i.e. energy) to the aircraft- you are just replacing that lost to drag. On a vertical launch, as you go higher you have less atmospheric drag to contend with- winged or not. > Air molecules are compressed by gravity and that compression gives lift > with a properly designed airfoil. This is utter nonsense. An airfoil will produce lift through forward motion whether the air is "compressed by gravity" or not. The lift is determined by the density of the fluid (air in this case), not by how it got to be that dense. Mike > Wings do not allow for less energy to be used to orbit a craft- while > they provide lift they do not provide any energy. In fact, since they > also generate drag, a winged vehicle would almost certainly require > more fuel to reach orbit, since the tubular design will have less > drag to overcome. Careful here. Wings do indeed save energy; this is because wings have a lift/drag ratio, the drag is approximately equal to the engine thrust, and so thrust can be reduced- reducing the propellant needed to carry the vehicle whilst within the atmosphere. The root cause of the energy saving is that the vehicle uses wing to throw air downwards relatively slowly; the slow speed represents lower energy needed to carry the vehicle; the high exhaust speed of rocket engines uses more energy (since energy goes as a square law on the exhaust velocity), although it saves propellant mass. Even with Apollo, studies showed that a lifting approach did indeed increase payload (although the payload increase was very marginal.) The big downside of wings is after you leave the atmosphere- wings push up dry mass, and then it is very easy to lose everything that was gained during ascent and then some; a good mass ratio is essential particularly toward the end of the burn. > Mike > The big downside of wings is after you leave the atmosphere- wings push > up dry mass, and then it is very easy to lose everything that was > gained during ascent and then some; a good mass ratio is essential > particularly toward the end of the burn. > >> Mike Which is another excellent reason to look at TSTO rather than STSO with current technology.  SignatureMalcolm Street Canberra, Australia The nation's capital > *From:* "Ian Woollard" <ian.woollard@gmail.com> > *Date:* Wed, 15 Mar 2006 19:42:39 -0000 [quoted text clipped - 29 lines] > > > Mike So the obvious approach is a two-stage one - fly the wings and atmospheric engines away once they no longer serve a good purpose. Spaceship One on steroids... > So the obvious approach is a two-stage one - fly the wings and > atmospheric engines away once they no longer serve a good purpose. The problem is that the optimum staging speed is about 3km/s. But the wings are normally only good for maybe mach 3 or so (1km/s); after that structural heating problems start to really get interesting. So you're compromising your first stage when you stick wings on in several different ways. > Spaceship One on steroids... Yes, but it might be observed that Spaceship One took two stages to do what one stage can do. Even Rutan admitted that a lot of the tech he used was because it was stuff that *he* knew how to do, rather than because it was inherently better (but he did have some good ideas, the pivoting tail structure seems to be a reasonably good idea.) > Wings use air to gain an advantage on gravity. How much air is there at typical Shuttle altitudes? How much advantage does air provide to wings at that altitude? > Today, however, a waverider design shouldn't be all that difficult with > the knowledge and materials base that exists in 2006. Titanium is [quoted text clipped - 3 lines] > solved the volume problem for hypergolic hydrogen/lox burners like the > SSME. Feel the breeze with all that handwaving. > Wings use air to gain an advantage on gravity. Therefore, they can > reach the airless void using less energy than a vertical tublular > rocket. The goal isn't getting to orbit using the least energy -- it's getting to orbit the cheapest, safest way. The energy expended by a rocket is often inexpensive LOX and LH2. LOX is virtually free and LH2 is a very low % of operating costs. It makes no sense using a tremendously complicated, very expensive hypersonic airbreathing winged vehicle to save a few dollars of propellant. > The proof that wings gain an advantage is that a bomber can reach > 20,000 feet and stay there for the hours it takes to reach target and > return on 1/10th of the thrust to weight ratio that a vertical tubular > rocket requires just to slowly leave the launch pad. This only illustrates that jet engines have much better specific fuel consumption than rockets. The B-52H TF33 jet engine has a specific fuel consumption of about 0.56 lb fuel per pound thrust per hr. The shuttle SSME consumes about 9.4 lb propellant per pound thrust per hr. A rocket can produce lots of thrust, but its specific propellant consumption is poor. It's better to let the rocket do what it does best -- produce lots of thrust and get out of the atmosphere quickly. Wings just slow you down. If you replaced the B-52's jet engines with rockets, it couldn't fly for hrs, despite having wings. It's not the wings that make the difference, it's the engine type. > In short, you have to get from here to orbit and the best method is a > winged or waverider vehicle. The best way is the cheapest, most reliable way. Cheap means a combination of operating costs and development costs. Nobody gives you an award for getting to orbit the most romantic way, or the coolest way. > The airfoil vehicle, however, is more > difficult to design than a vertical tubular rocket. You've got that part right. A winged hypersonic airbreathing orbital launcher is so difficult nobody has figured out how to do it. > a waverider design shouldn't be all that difficult with > the knowledge and materials base that exists in 2006. Add about a hundred years to that and you're closer to correct. > And, slush hydrogen tanks have > solved the volume problem for hypergolic hydrogen/lox burners like the > SSME. Hydrogen/LOX engines are NOT hypergolic. -- Joe D. Various attempts have been made to design hypersonic airbreathing engines. The X-43 is probably the only one to fly, even briefly. The problem with scramjets is that they tend to be efficient only in a narrow range of speeds; great for a cruise missile but not for orbital launch. The liquid air cycle (i.e. hotol) is less speed sensitive but there's no easy way to carry enough cooling capacity to actually liquify all the air you need. Best bet might essentially be a cooled-inlet turbojet. Wings can be useful for thrust-limited designs, but a launch vehicle goes through the speed regiemes quickly and above about 30 KM wings aren't much use. After attacking the SSTO problem for awhile, at some point a two-stage solution begins to look more practical. > Various attempts have been made to design hypersonic airbreathing > engines. The X-43 is probably the only one to fly, even briefly. The [quoted text clipped - 8 lines] > for awhile, at some point a two-stage solution begins to look more > practical. Why bother with air breathing, winged vehicles at all? Why not consider a conventional, rocket powered VTVL TSTO? Such a design wouldn't even need an altitude compensating engine (i.e. aerospike), since the first stage would be optimized for low altitudes and the second stage for vacuum. Jeff SignatureRemove icky phrase from email address to get a valid address. > The liquid air cycle (i.e. hotol) is less speed sensitive but > there's no easy way to carry enough cooling capacity to actually > liquify all the air you need. Best bet might essentially be a > cooled-inlet turbojet. Alternately, there is SABRE. http://en.wikipedia.org/wiki/SABRE Which might be that "cooled inlet turbojet" you mentioned. > After attacking the SSTO problem > for awhile, at some point a two-stage solution begins to look more > practical. Yes, though sometimes the SSTO looks tempting, like when you find a very lightweight dense fuel design. Mike Miller [...] > Wings use air to gain an advantage on gravity. Therefore, they can > reach the airless void using less energy than a vertical tublular > rocket. That last statement is debatable. When you want to reach orbit, height isn't important, and speed is. Since speeds approaching orbital velocities are deeply unhealthy in an atmosphere, you're going to want to do the bulk of your acceleration when you're above it. The usual flight profile of a launching spacecraft is to go vertically up through the bulk of the atmosphere, and then rotate sideways and accelerate sideways once it's above it. All wings will do here is to add on weight and drag, which will eat into your payload. [...] > The proof that wings gain an advantage is that a bomber can reach > 20,000 feet and stay there for the hours it takes to reach target and > return on 1/10th of the thrust to weight ratio that a vertical tubular > rocket requires just to slowly leave the launch pad. Sure, but that bomber isn't in orbit. The fastest jet aircraft ever made was the Lockheed SR-71, which managed to get to Mach 3.3. Orbital velocity is about equivalent to Mach 25. I think you might be confusing being in orbit with being high up. There is some benefit for being high up when you launch a spacecraft; but it's got nothing to do with speed. Instead it's all about being able to avoid having to fly your very energy-expensive rocket through a thick atmosphere and having to have to use rocket nozzles optimised for sea-level air. So, basically: on the way up, wings are a drag. (Literally.) They're heavy and get in the way. On the way down, they're definitely useful, but there are other approaches that are lighter and more effective, such as a inflatable parasail: it's a fraction of the weight of a fixed wing, and doesn't impose drag on launch. SSTOs are so marginal anyway that the cost of adding a wing, with undercarriage, reinforced stress structure etc may well put you completely out of business. - -- +- David Given --McQ-+ | dg@cowlark.com | "Never attribute to malice what can be adequately | (dg@tao-group.com) | explained by stupidity." --- Nick Diamos +- www.cowlark.com --+ > Wings use air to gain an advantage on gravity. Therefore, they can > reach the airless void using less energy than a vertical tublular > rocket. The goal isn't getting to orbit using the least energy -- it's getting to orbit the cheapest, safest way. The energy expended by a rocket is often inexpensive LOX and LH2. LOX is virtually free and LH2 is a very low % of operating costs. I think you made that point before; I'm not saying you disagree with it. It makes no sense using a tremendously complicated, very expensive hypersonic airbreathing winged vehicle to save a few dollars of propellant. > The proof that wings gain an advantage is that a bomber can reach > 20,000 feet and stay there for the hours it takes to reach target and > return on 1/10th of the thrust to weight ratio that a vertical tubular > rocket requires just to slowly leave the launch pad. This only illustrates that jet engines have much better specific fuel consumption than rockets. The B-52H TF33 jet engine has a specific fuel consumption of about 0.56 lb fuel per pound thrust per hr. The shuttle SSME consumes about 9.4 lb propellant per pound thrust per hr. A rocket can produce lots of thrust, but its specific propellant consumption is poor. It's better to let the rocket do what it does best -- produce lots of thrust and get out of the atmosphere quickly. Wings just slow you down. If you replaced the B-52's jet engines with rockets, it couldn't fly for hrs, despite having wings. It's not the wings that make the big difference, it's the engine type. > In short, you have to get from here to orbit and the best method is a > winged or waverider vehicle. The best way is the cheapest, most reliable way. Cheap means a combination of operating costs and development costs. Nobody gives you an award for getting to orbit the most romantic way, or the coolest way. > The airfoil vehicle, however, is more > difficult to design than a vertical tubular rocket. Boy, is that right.. A winged hypersonic airbreathing orbital launcher is so difficult nobody has figured out how to do it. > a waverider design shouldn't be all that difficult with > the knowledge and materials base that exists in 2006. Add about a hundred years to that and you're closer to correct. > And, slush hydrogen tanks have > solved the volume problem for hypergolic hydrogen/lox burners like the > SSME. Hydrogen/LOX engines are NOT hypergolic. -- Joe D. > Wings use air to gain an advantage on gravity. Therefore, they can > reach the airless void using less energy than a vertical tublular > rocket. Not necessarily. A winged vehicle necessarily spends more time in the atmosphere; and hence spends more fuel on atmospheric drag. In addition, because it spends more time to reach orbit, the gravity losses are higher; although they are offset by the higher efficiencies of wings at supporting the vehicle. Finally, winged vehicles are much less efficient on the final orbital insertion burn; the dry mass is very significantly increased by the presence of wings- this makes the final insertion burn require multiple times more fuel. Unless you are using an airbreathing engine it's all at best a wash or only very modest improvements indeed. > They also enable a spacecraft to 'fly' to a runway and land > softly after deorbit. Yes, although landing speeds can be very high. > The proof that wings gain an advantage is that a bomber can reach > 20,000 feet and stay there for the hours it takes to reach target and > return on 1/10th of the thrust to weight ratio that a vertical tubular > rocket requires just to slowly leave the launch pad. Yes, although that is more to do with high ISP of airbreathing engines and the high lift/drag ratio that is achievable only at low speeds. > Today, however, a waverider design shouldn't be all that difficult with > the knowledge and materials base that exists in 2006. Titanium is [quoted text clipped - 3 lines] > solved the volume problem for hypergolic hydrogen/lox burners like the > SSME. All those things were known about when the Shuttle was built. It's not that simple. > tomcat > > Wings use air to gain an advantage on gravity. Therefore, they can > > reach the airless void using less energy than a vertical tublular > > rocket. > > Not necessarily. A winged vehicle necessarily spends more time in the > atmosphere; and hence spends more fuel on atmospheric drag. Not necessarily: NASA Helios Prototype flew to 96,863 feet in 2001 using propellers shovelling air powered by 28 horsepower motors fueled by sunlight from solar cells on it's wings. Helios was designed as proof of concept for "atmospheric satellites" intended to stay aloft for weeks, or months at a time, refuling daily from solar power above the clouds. The issue with wings is wingloading. Helios had 13 ounces loading per square foot of wing. The Piper Cub has 6.7 pounds. The Concorde had 12 pounds. You don't mind thinking big about fuel expendatures and thinking big about money expendatures -- try thinking BIG about wings. The SKYLON is being designed to mine oxidizer from the atmosphere. http://en.wikipedia.org/wiki/Skylon http://www.reactionengines.co.uk/main.php?content=index Up to 5.5 mach it is airbreathing. The ratio of H2 to O2 is 1:8 by weight. 8/9ths of the weight of the fuel mixture is not airlifted until the air is very much thinner than sea level. THEN, getting up to speed the O2 is brought onboard, AFTER the air density is far less than one tenth as thick. Skylon has stubby little wings, which is why its projected payload is so low. Try thinking 20 pounds or less per square feet of wing and you come up with a biplane that looks more like the Concorde riding piggyback on the B2-Spirit (with 8,000+ square feet of wings). > In > addition, because it spends more time to reach orbit, the gravity > losses are higher; although they are offset by the higher efficiencies > of wings at supporting the vehicle. There is no such thing as "gravity losses" as long as a vehicle is ascending. Gravity losses kick in when you can't go higher and you are still burning fuel. Using one 50th of the Shuttle's fuel to go to 100,000 feet is no loss if you still have enough fuel at 100,000 feet to get your air-launched vehicle to orbit > Finally, winged vehicles are much > less efficient on the final orbital insertion burn; the dry mass is > very significantly increased by the presence of wings- this makes the > final insertion burn require multiple times more fuel. Dry mass just "is". It is not more or less detrimental for it to be wings than it is to be anvils in the cargo bay. Wings are only significant help or hinderence where there is air. Where there is no air it doesn't matter what shape of appendages are sticking out. Thin air continues to provide lift if the speed is high enough, and the speed gets higher the thinner the air because of less air drag, so that works out splendidly all the way around. As the air gets too thin for lift it gets too thin for appreciable drag also. The fuel is not the problem. The oxidizer is the problem because it weighs so much. Oxygen weighs 16 atomic weight units for ever 1 of Hydrogen. NASA's Shuttle expends a million pounds of fuel and oxidizer to get the first 100,000 feet, the same altitude they got with 28 horsepower of electric motors turning propellers shovelling air, powered by solar cells. http://en.wikipedia.org/wiki/Earth%27s_atmosphere "An altitude of 120 km (75 mi or 400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry. The Karman line, at 100 km (62 mi), is also frequently used as the boundary between atmosphere and space." One can assume the reverse is true: if atmosphere friction becomes noticeable at 120 km, than wings are still providing some lift so long as the speed is high enough to invoke Newton's Law of equal and opposite reactions. > Unless you are using an airbreathing engine it's all at best a wash or > only very modest improvements indeed. [quoted text clipped - 3 lines] > > Yes, although landing speeds can be very high. Because the wings are too small. More wings mean slower descent. Yes it's hot at first by there's soon a cold high strata which can shed that heat by flying around in it for a while in a mostly empty spaceplane with lot's of glide lift. They soft land capsules with parafoils made of cloth, and they do it on Mars where the air is as thin as it is at 100,000 feet. There's no reason a big like kite-like spaceplane can't soft-land on it's airport of choice. > > The proof that wings gain an advantage is that a bomber can reach > > 20,000 feet and stay there for the hours it takes to reach target and [quoted text clipped - 3 lines] > Yes, although that is more to do with high ISP of airbreathing engines > and the high lift/drag ratio that is achievable only at low speeds. Again, jets don't have to carry their oxidizer. High lift is proportional to Newton's law, not speed. It has to do with collisions of air molecules from the surfaces of the travelling aircraft. When there is significantly more lift on the undersurfaces than above, the craft flies, otherwise it sinks. Waverider vehicles are intended to ride on hypersonic compression lift and do it above mach 8. http://en.wikipedia.org/wiki/Waverider Where there is not enough air to collide with the undersurfaces there is no lift and likewise no drag either. Then the only force is Newton's law applying to propellent exhaust. > > Today, however, a waverider design shouldn't be all that difficult with > > the knowledge and materials base that exists in 2006. Titanium is [quoted text clipped - 6 lines] > All those things were known about when the Shuttle was built. It's not > that simple. Right. It's not simple. Nobody, not the superpowers, not the second tier nations, not the biggest corporations nor the smallest, has ever launched a SSTO to LEO and back. SpaceShipOne only got 1/3rd the way there and that wasn't SSTO, it was two staged, carried on White Knight. Wings are cheaper than fuel. Before last year's oil price gouging carbon-fiber fabric was down to $0.94 square foot for 6kx6k 2,000,000 psi, wholesale in volume lots. The cost of 10,000 square feet of wings in material costs was less than buying a Piper Cub used. Now Exxon got their price raise and it costs a NEW Piper Cub. There's a lot of pnoney baloney on the internet about how cheap H2 and O2 is. Some say NASA pays $0.08 a kilogram for LOX, but that doesn't add up. Just trucking it from Mississippi to KSC in 4,000 gallon tankers has to cost $1/gallon for shipping, or do you believe in the "fuel fairy" giving away fuel below costs? Somebody needs to do a price breakdown on the price of a Shuttle launch: prices from $1.2 billion to $55 million are tossed around, with $500 million per launch being the favorite of more people. NASA themselves says that the cost of payload is $10,000 per pound. Five kilos of drinking water for the ISS would buy 10,000 square feet of wing material. There's probably more than 10,000 square feet of wing material in that big External Tank they throw away each launch. More Wings, Less Fuel. If you have to think BIG, think BIG about stuff you don't throw away every launch instead of big fuel bills and big disposible tanks. > The fuel is not the problem. The oxidizer is the problem because it > weighs so much. No, that's not really a problem. After all, you're throwing it away during flight, and rocket engines are light for the thrust they deliver. Much lighter than propellers, wings, and jet engines. > Wings are cheaper than fuel. Before last year's oil price gouging > carbon-fiber fabric was down to $0.94 square foot for 6kx6k 2,000,000 [quoted text clipped - 4 lines] > There's a lot of pnoney baloney on the internet about how cheap H2 and > O2 is. Funny, you also just used some very dubious accounting. Have you looked at the price it takes to build a wing once you factor in research and development, labor, and all other costs that go into the final price tag? The material cost of the space shuttle, or 747, or F22, is a trivial cost component. I assure you, the F22 isn't $130 million because of the materials costs. In fact, it's noteworthy how the F22's price drops as the production quantities go up. Carbon material prices... I recently (2004) priced out a custom-made carbon-epoxy case for some electronics. The prototype would've run about $3000, with $100 of that being off-the-shelf materials the composite firm had in stock (and trust me, they were marking up the materials prices.) Get some carbon-epoxy board from the warehouse, cut to shape, glue together - simple, fast, and $3000 once you got done paying for the engineering and assembly labor. It was a crude demonstrator unfit for service, just something to show to the client. Incidentally, I settled on a modified off-the-shelf aluminum case. Thin, stamped sheet aluminum using existing molds and, actually, fewer cutting operations than the basic case. Price: $8000, and it wasn't for the cost of the sheet aluminum ($20). I've made carbon-carbon composites, simple shapes that would be suitable for brake pads. The cost of the carbon fiber was, as you noted, cheap. In 3 hours of running the CVD furnace, we burned $500 in electricity to produce a hocky puck-sized piece of carbon-carbon, nevermind the hours of labor spent setting up the furnace, making the carbon fiber preforms, paying the bureaucracy that supported the research lab. (All those extra expenses were worked into the overall labor cost - I only wish I made $100/hour like we billed.) In fact, most C-C production can take a couple of weeks in a furnace, not 3 hours, with interruptions for machinists to carve off crusts. $0.94 per square foot of material is a number that has NOTHING to do with the cost of a wing. It's a footnote some junior clerk will scribble in under labor, overhead, and tooling costs. > Some say NASA pays $0.08 a kilogram for LOX, but that doesn't > add up. Just trucking it from Mississippi to KSC in 4,000 gallon > tankers has to cost $1/gallon for shipping, or do you believe in the > "fuel fairy" giving away fuel below costs? Why don't you send Praxair or Air Liquide an email and ask what a 4000-gallon LOX delivery to your front door costs? I really doubt the LOX will be shipped from Mississippi, though. Most major industrial gas distributers have production facilities in every state, and will offer to hook you up with an on-site LOX production unit if your demand is high enough. > Somebody needs to do a price breakdown on the price of a Shuttle > launch: prices from $1.2 billion to $55 million are tossed around, with > $500 million per launch being the favorite of more people. $55 million is about the cost of direct expenses for launching the shuttle - including the fuel. $500 million is about the cost when NASA gets done billing for labor for its army of workers. > More Wings, Less Fuel. If you have to think BIG, think BIG about stuff > you don't throw away every launch instead of big fuel bills and big > disposible tanks. If you launch the same vehicle over and over, perhaps several dozen times per year, yeah, the fuel might get to be an issue. Until then, it's still an inexpensive component of operating a spacecraft. Adding several billion dollars to the expense of engineering a vehicle to have wings is another issue. Mike Miller, Materials Engineer [...] > Not necessarily: NASA Helios Prototype flew to 96,863 feet in 2001 > using propellers shovelling air powered by 28 horsepower motors fueled > by sunlight from solar cells on it's wings. Yes; *very slowly*, which makes it entirely irrelevant when dealing with orbital vehicles. The thing is... [...] > You don't mind thinking big about fuel expendatures and thinking big > about money expendatures -- try thinking BIG about wings. [...] > Skylon has stubby little wings, which is why its > projected payload is so low. ..big wings mean big drag. For the kind of velocities you need to get into orbit, big drag is fatal. Not only will you have to burn fuel in order to counter the drag, but as soon as you get above the point where the wings help give you lift, you end up having to carry them by sheer rocket power - --- which is a waste. And since you reach that point very quickly, it's generally not considered worth the effort. Forgive me for saying so, I think you're still under the impression that going high is sufficient to get into orbit. It's not, and in fact it's largely irrelevant. Orbit's all about going *fast*. You can't go fast in an atmosphere. [...] > There is no such thing as "gravity losses" as long as a vehicle is > ascending. Gravity losses kick in when you can't go higher and you are > still burning fuel. I'm sorry, but this is simply incorrect. Gravity losses apply all the time your vehicle is in the air. Gravity is continuously trying to accelerate your vehicle downwards at 9.8 m/s/s; you have to apply, at minimum, enough force to counter that. If your rocket is sufficient to accelerate your vehicle in at 10 m/s/s in flat space, then under gravity you're only going to accelerate upwards at 0.2 m/s/s --- most of your thrust is being wasted. Those are gravity losses. [...] > Dry mass just "is". It is not more or less detrimental for it to be > wings than it is to be anvils in the cargo bay. Wings are only > significant help or hinderence where there is air. Where there is no > air it doesn't matter what shape of appendages are sticking out. On the contrary --- customers are paying you to lift those anvils, but they're not paying you to lift the wings. Every kilo of unnecessary structure is one kilo of cargo you can't carry. Wings are unavoidably heavy; they're a crucial part of your vehicle's stress structure. [...] > One can assume the reverse is true: if atmosphere friction becomes > noticeable at 120 km, than wings are still providing some lift so long > as the speed is high enough to invoke Newton's Law of equal and > opposite reactions. *nods* ..except, wings *only* work if they're interacting with the atmosphere, which means drag. That's how they work. If your wings didn't have any drag, they wouldn't give you any lift, by definition. So, you're going to have to burn fuel to counter that drag. Wings are only useful if: (fuel needed to power wings when in atmosphere) + (fuel needed to lift wings when above atmosphere) is less then: (fuel saved by having wings) With current state-of-the art, this is not the case, and given that most spacecraft are in the atmosphere for a very brief amount of time --- for the space shuttle, this is about two minutes --- it's not considered worth the hassle. [...] > Waverider vehicles are intended to ride on hypersonic compression lift > and do it above mach 8. You should look into what engines are available that will breathe air at mach 8; currently the total number is 0. Air-breathing hypersonic engines are very, very hard, largely due to the fact that you have to slow the air down enough so that your engine can interact with it. This involves drag, and lots of it, which means your engine has to produce enough thrust to counter the drag, and frankly the added weight and complexity mean that again, it's not worth the hassle. Particularly since once you're above the atmosphere you're going to have to lift all that dead weight with your conventional rockets, which you're going to have to carry anyway. [...] > SpaceShipOne only got 1/3rd the way there and that wasn't SSTO, it was > two staged, carried on White Knight. No. No, it didn't. SS1 reached Mach 3. Orbit is about the equivalent of Mach 25. That's 1/8 of the way. - -- +- David Given --McQ-+ "Hydrogen fusion, the sun makes shine | dg@cowlark.com | Vascular pressure makes the ivy twine. | (dg@tao-group.com) | Because of Rayleigh, the sky's so blue. +- www.cowlark.com --+ Hormonal fixation is why I love you." --- Zarf </pre> > [...] > > SpaceShipOne only got 1/3rd the way there and that wasn't SSTO, it was > > two staged, carried on White Knight. > > No. No, it didn't. SS1 reached Mach 3. Orbit is about the equivalent of Mach > 25. That's 1/8 of the way. Actually it much worse than 1/8 of the way. In terms of energy that eight to one velocity increase takes 128 times more energy. As you can see SpaceShipOne was far from getting to orbit. SignatureMike Swift Two things only the people anxiously desire‹bread and circuses. Decimus Junius Juvenalls >> [...] >> > SpaceShipOne only got 1/3rd the way there and that wasn't SSTO, it was [quoted text clipped - 7 lines] > eight to one velocity increase takes 128 times more energy. As you can > see SpaceShipOne was far from getting to orbit. The intention was never to get it into orbit. The question to ask yourself, is if NASA were given the task to create a reusable vehicle to carry three people to 50 miles altitude and back, what would *that* have cost? Ask the same question only substitute any large aerospace contractor for NASA. Jeff SignatureRemove icky phrase from email address to get a valid address. >> In >> addition, because it spends more time to reach orbit, the gravity [quoted text clipped - 6 lines] > 100,000 feet is no loss if you still have enough fuel at 100,000 feet > to get your air-launched vehicle to orbit You're showing your ignorance here and are handwaving away a very basic part of the equation. There most certainly are gravity losses even if the vehicle is ascending. Essentially, the slower you accellerate to orbital altitude *and* velocity, the higher your gravity losses will be. > The fuel is not the problem. The oxidizer is the problem because it > weighs so much. Oxygen weighs 16 atomic weight units for ever 1 of > Hydrogen. NASA's Shuttle expends a million pounds of fuel and oxidizer > to get the first 100,000 feet, the same altitude they got with 28 > horsepower of electric motors turning propellers shovelling air, > powered by solar cells. But the shuttle is moving at considerably higher velocity at 100k feet. More importantly, spending time in the atmosphere to "save" on the mass of LOX is silly if your goal is to get to LEO, especially considering that LOX is one of the cheapest fluids on the planet since it's literally made from air. > Wings are cheaper than fuel. Before last year's oil price gouging > carbon-fiber fabric was down to $0.94 square foot for 6kx6k 2,000,000 > psi, wholesale in volume lots. The cost of 10,000 square feet of wings > in material costs was less than buying a Piper Cub used. Now Exxon got > their price raise and it costs a NEW Piper Cub. You're showing your ignorance again. $0.94 per square foot for carbon fiber fabric isn't what's expensive. It's the cost of the machines, labor, and time it takes to turn that into a wing that kills you. More than one friend of mine used to work for a US company that makes carbon fiber tape laying machines. Just writing the programs to lay the tape isn't easy... > There's a lot of pnoney baloney on the internet about how cheap H2 and > O2 is. Some say NASA pays $0.08 a kilogram for LOX, but that doesn't > add up. Just trucking it from Mississippi to KSC in 4,000 gallon > tankers has to cost $1/gallon for shipping, or do you believe in the > "fuel fairy" giving away fuel below costs? Look again at launch prices (i.e. $ per lb to LEO) and compare them to the price of fuel ($ for fuel to get 1 lb to LEO). It's not the high price of fuel that is keeping launch costs so high. > Somebody needs to do a price breakdown on the price of a Shuttle > launch: prices from $1.2 billion to $55 million are tossed around, with [quoted text clipped - 3 lines] > wing material. There's probably more than 10,000 square feet of wing > material in that big External Tank they throw away each launch. The ET's LOX tank holds about 20,000 cubic feet of LOX. A quick search says LOX weighs 64 lb per cubic foot, giving you 1,280,000 lbs of LOX in the ET. If a shuttle launch costs $500 million, LOX would need to cost you about $4 per lb to make up just 1% of the total cost to launch the shuttle. Actual cost for LOX production (minus transportation costs) is reportedly pennies per pound. Even rocket grade kerosene costs you less than $4 per lb. Here's part of an old (1996) posting from Henry Spencer: <begin old posting> If using LOX/kerosene, you need about 20 pounds of mix to lift a pound into orbit, and maybe, oh, a fifth of those pounds are payload, so you need 100 pounds of fuel+oxidizer. Now, LOX costs about 4c/pound, and is about 3/4 of the mix. Kerosene costs depend on grade, but expensive rocket-grade stuff is maybe 25c/pound. So the average mix cost is circa 10c/pound, and total propellant costs are about $10 per pound of payload. Figuring me at 200 pounds, that's $2000. Not quite as cheap as London to New York, agreed, but not much more than what I paid for a round trip from Toronto to Australia some years ago. <end old posting> In other words, the high cost of fuel isn't what makes spaceflight expensive when launch costs fare more than the cost of fuel for the launch. Now tell us again how the high price of LOX is making launch costs so high. :-) Jeff SignatureRemove icky phrase from email address to get a valid address. >>In other words, the high cost of fuel isn't what makes spaceflight expensive when launch costs fare more than the cost of fuel for the launch. Exactly. Almost all the cost for the Shuttle is the maintenance needed between flights. Some parts, like the SRBs, are completely disassembled, stripped to bare metal (even the nuts and bolts), inspected for cracks, and remanufactured. The Orbiter requires months of inspections and maintenance. But these aren't the inevitable result of the vehicle being reusable; they're with us because the Shuttle was designed before we had any actual flight experience with many of the critical systems, particularly the TPS and SRBs. Analysis is not equivalent to experience; the predictions of operating cost and reliability were off by a factor of at least 10. The technology demonstrators (X-33, X-34, DC-X, X-37) would have provided the flight experience to do it better next time. But we are about to learn the wrong lesson. Instead of taking what we've learned and designing a reusable launch vehicle that is practical and safe, we have decided that reusable spacecraft are by nature expensive and unreliable. >>>In other words, the high cost of fuel isn't what makes spaceflight >>>expensive [quoted text clipped - 8 lines] > designed before we had any actual flight experience with many of the > critical systems, particularly the TPS and SRBs. Actually, the problem really was with the SRB's themselves. As with many orbiter systems, they were chosen because of their low development costs, not because NASA thought they would have low per flight costs. Also, the TPS on the orbiter isn't the only labor intensive system. There are also the SSME's (their high chamber pressure drove them to a design that's bleeding edge), the APU's (toxic propellants), the RCS/OMS systems (which use toxic propellants), and etc. Jeff SignatureRemove icky phrase from email address to get a valid address. > Exactly. Almost all the cost for the Shuttle is the maintenance needed > between flights. Some parts, like the SRBs, are completely > disassembled, stripped to bare metal (even the nuts and bolts), > inspected for cracks, and remanufactured. Could you please give an example of an SRB segment that has been reused, including the flight on which it was first used, and the flight on which it was reused. SignatureBruce | 41.1670S | \ spoken | -+- Hoult | 174.8263E | /\ here. | ----------O---------- > Could you please give an example of an SRB segment that has been reused, > including the flight on which it was first used, and the flight on which > it was reused. Odd request, considering that SRB segment reuse is the norm, not the exception. One bit of trivia. The parachutes for the SRB's have to be washed between flights, due to their being dunked in salt water at the end of every flight. That task must require the world's largest washing machine. ;-) Jeff SignatureRemove icky phrase from email address to get a valid address. >> Could you please give an example of an SRB segment that has been reused, >> including the flight on which it was first used, and the flight on which [quoted text clipped - 7 lines] > flight. > That task must require the world's largest washing machine. ;-) There are pictures of it on the net, but I forget where. Jeff Findley included: > > Could you please give an example of an SRB segment that has been reused, > > including the flight on which it was first used, and the flight on which > > it was reused. > > Odd request, considering that SRB segment reuse is the norm, not the > exception. So give the requested example. I'm curious too. The norm is not established by zero examples, nor by NASA statements that say reuse is possible but nowhere that it has happened. --- Graham Cowan, former hydrogen fan Boron: internal combustion, nuclear cachet http://tinyurl.com/4xt8g > > Wings are cheaper than fuel. Before last year's oil price gouging > > carbon-fiber fabric was down to $0.94 square foot for 6kx6k 2,000,000 > > psi, wholesale in volume lots. The cost of 10,000 square feet of wings > > in material costs was less than buying a Piper Cub used. Now Exxon got > > their price raise and it costs a NEW Piper Cub. Comparing an air breathing winged vehicle to a VTVL all rocket vehicle the VTVL has the following advantages. Low landing speed of about 3 mph, vs 220 mph for a winged lander. The vehicle has about 10% less hardware (no wings or wheels). Because there are no wings or wheels they can't fail (Shuttle). Hardware costs are in the neighborhood of $1000 per kilogram, and propellents $0.50 per kilogram. With these numbers the break even point for cost is at 250 flights per year for a vehicle designed for a ten year life, and it will be a long time before we have shuttles running that schedule. No specialized runways required to land. In an emergency it can land on any firm level ground (DC-X). Wings are of use only for the first two minutes of a mission, and the last one minute. Wheels are used only the last 30 seconds of the flight. Many engineers and managers like wings and wheels because they are a known quantity. They don't like the Buck Rogers stuff, at least until someone else does it, then it will be all the rage. SignatureMike Swift Two things only the people anxiously desire, bread and circuses. Decimus Junius Juvenalls > *From:* Mike Swift <tomswift@cruzio.com> > *Date:* Wed, 15 Mar 2006 19:42:27 -0000 [quoted text clipped - 24 lines] > like the Buck Rogers stuff, at least until someone else does it, then > it will be all the rage. The DC-X approach still needs the mass equivalent of the wheels unless you plan to use an aerospike engine and land on the plug... As for the wings, can someone with the knowledge of the right maths do some for us? Surely the critical factor is whether the mass of extra fuel required to get down safely on engine thrust is less than the mass of the wings? In both cases you have to carry that mass into orbit and back again. Obviously I'm assuming a Shuttle-like gliding approach rather than a powered return for the winged vehicle. Personally I incline towards a two-stage vehicle with the first stage being winged and capable of returning to base. It may even be economic, albeit somewhat dangerous, to use an air rendezvous approach on return so the air-breathing first stage does the landing too and so can land anywhere. > The DC-X approach still needs the mass equivalent of the wheels unless > you plan to use an aerospike engine and land on the plug... But in the vertical landing approach, the "wheels" don't have to roll, and the landing gear can be sized for a touchdown at a few m/s rather than 100 m/s. As others have said, the mass tradeoff is between (wings plus wheels) for horizontal landing versus (propellant plus parachute plus landing skids) for vertical. I don't think it's entirely obvious how this tradeoff comes out, though I'd guess it probably favors vertical landing. To make things even more complicated, there are other tradeoffs to be made besides mass. One example is required cross-range capability. |
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