A kerosene-fueled X-33 as a single stage to orbit vehicle.
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From: Robert Clark on 4 May 2010 13:49 On May 3, 6:31 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > No matter which way you slice it, lifting a mass against gravity > will give it potential energy to fall again. Putting it in orbit means > giving it kinetic energy as well. During re-entry both the KE and > PE are lost as heat, which is why all vehicles designed for re-entry > have heat shields. So at the end of the excursion, with energy > being a conserved quantity, all of the energy in the fuel has been > converted to heat which is then radiated into space. > Your problem isn't to find a trajectory, it is to find how to put > mass into orbit at minimum cost. That is, find joules per dollar > for the type of fuels and oxidants and the technology available, > whether it is kerosene-oxygen, hydrogen-oxygen, old rubber tyres, > nitromethane for "Top Fuel" drag racing or nitro-glycerine! > ... > Nowhere in your analysis above have you considered that. > > The laws of physics and chemistry cannot be defeated, it is only economics > that you can meddle with, joules per dollar. I have to tell you honestly > that you'll never convince an aeronautical engineer of your quick fix, > you've left out far too much reality. The advantage of using kerosene or other dense propellant is that in the same size vehicle you can carry much more propellant. Since the cost of a launch vehicle is strongly dependent on its physical size, by using dense propellants you get more joules per dollar. Note that another key aspect of having a vehicle so weight optimized that it can be SSTO, is that if you do want to get a larger payload to orbit you can use those SSTO vehicles in stages. Since they are so weight optimized, these weight savings can go to carrying greater payload. We'll estimate the payload we can loft to orbit with two X-33's mated in bimese fashion, where two similar vehicles serve as the first and second stages. See for instance the attached image from this report: Simulation and Analyses of Staging Maneuvers of Next Generation Reusable Launch Vehicles. Bandu N. Pamadi1, Thomas A. Neirynck2, Peter F. Covell3 NASA Langley Research Center, Hampton, VA Nathaniel Hotchko4, David Bose5 Analytical Mechanics Associates, Inc., Hampton, VA http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.81.4885&rep=rep1&type=pdf Figs 1-4, Bimese booster and orbiter. http://i42.tinypic.com/14a92y9.jpg Using two similar reusable vehicles for both stages has been estimated to save on development costs. The reconfigured X-33 with three NK-33 engines we calculated to have a dry weight of 21,700 kg, and carry 307,000 kg of kero/LOX propellant. However, to maximize performance we'll use aerospike nozzles on the engines. The NK-33 had a 331 s vacuum Isp. But this is because the engine had a nozzle that was a compromise between optimal sea level and vacuum performance. With an aerospike nozzle it could get the ca. 360 s vacuum Isp of other Russian high performance kerosene engines. We'll also take its sea level Isp as the ca. 331 s of some first stage optimized Russian engines. Since the vehicles will be mated symmetrically instead of one standing vertically atop another, what I'll call the first stage or booster is the one that stops firing first, separates from the second one, does not go to orbit, and returns to the launch site. The second or upper stage, or orbiter, will be the one that goes on to orbit. We'll have all 6 engines firing from both X-33's for the first part of the trip. However, we want to have the upper stage X-33 to be fully fueled for the second stage firing, so we'll use cross-feed fueling to have fuel from the first stage provide the fuel for the upper stage also for the first portion of the trip where they are still connected. Let's calculate the payload that could be carried, taking again the required delta-V as 8,500 m/s. Take as an estimate 35,000 kg for the payload. The gross liftoff mass will then be 2x21,700 + 2x307,000 + 35,000 kg = 692,400 kg. The amount of fuel we'll be using for this first portion of the trip will be the amount stored in the booster, 307,000 kg, then this stage will separate and return to the launch site. The total mass at the end of this first portion will be 385,400 kg. For this first portion of the trip I'll take the Isp as the midpoint of the sea level and vacuum values so 345 s. Then the delta-V we can reach for this first portion will be 345*9.8ln(1 + 307,000/385,400)=1,981 m/s. For the second portion of the trip with just the upper stage remaining, the propellant mass will again be 307,000 and the mass at the end of this final burn will be 21,700 + 35,000 kg = 56,700 kg. So the delta-V reached here will be 360*9.8ln(1+307,000/56,700) = 6,557 m/ s, for a total delta-V of 8,538 m/s. This is for using kero/LOX as propellant. But this is not the most efficient dense propellant combination to use. Others can result in even greater payload to orbit. For instance as described here some hydrocarbon fuels when also densified by subcooling could result in 50% greater payload than kero/LOX: Alternate Propellants for SSTO Launchers. Dr. Bruce Dunn Adapted from a Presentation at: Space Access 96 Phoenix, Arizona April 25 27, 1996 http://www.dunnspace.com/alternate_ssto_propellants.htm So possibly we could get 52,000 kg payload to orbit. What would be the launch costs? I estimated before a single reconfigured X-33 might cost $4,500,000 per launch: Newsgroups: sci.space.policy, sci.astro, sci.physics, sci.space.history From: Robert Clark <rgregorycl...(a)yahoo.com> Date: Thu, 18 Mar 2010 12:02:10 -0700 (PDT) Subject: Re: A kerosene-fueled X-33 as a single stage to orbit vehicle. http://groups.google.com/group/sci.space.policy/msg/ffdb7503f156553e?hl=en So lets say the bimese launcher would cost twice this to $9,000.000 per launch. Then at a 52,000 kg payload, this would amount to a $9,000,000/52,000kg = $173/kilo cost to orbit, or only $80/lb, a *major* reduction in the costs to orbit. Bob Clark
From: Androcles on 4 May 2010 14:28 "Robert Clark" <rgregoryclark(a)yahoo.com> wrote in message news:01ac8580-fa1e-451b-9c77-2543bb3e163a(a)o11g2000yqj.googlegroups.com... On May 3, 6:31 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > No matter which way you slice it, lifting a mass against gravity > will give it potential energy to fall again. Putting it in orbit means > giving it kinetic energy as well. During re-entry both the KE and > PE are lost as heat, which is why all vehicles designed for re-entry > have heat shields. So at the end of the excursion, with energy > being a conserved quantity, all of the energy in the fuel has been > converted to heat which is then radiated into space. > Your problem isn't to find a trajectory, it is to find how to put > mass into orbit at minimum cost. That is, find joules per dollar > for the type of fuels and oxidants and the technology available, > whether it is kerosene-oxygen, hydrogen-oxygen, old rubber tyres, > nitromethane for "Top Fuel" drag racing or nitro-glycerine! > ... > Nowhere in your analysis above have you considered that. > > The laws of physics and chemistry cannot be defeated, it is only economics > that you can meddle with, joules per dollar. I have to tell you honestly > that you'll never convince an aeronautical engineer of your quick fix, > you've left out far too much reality. The advantage of using kerosene <SNIP> ======================================= You have not addressed the issue, snipping won't make it go away no matter how much you wish it would, and I can snip too. Airliners burn two tons of fuel on take-off and throttle back to cruise. They have the advantage of using atmospheric oxygen up to 50,000 feet (10 miles) and normally cruise economically at 30,000 feet where the air is thin enough to reduce drag and thick enough to breathe (they are pressurised to 8000 feet, compressors force air into the cabin). If you've ever flown you'll know your ears pop. But to reach the ISS an altitude of 200 miles is needed, so an oxidant needs to be lifted along with the fuel for the other 190 miles. http://en.wikipedia.org/wiki/Space_Shuttle_external_tank "A Space Shuttle External Tank (ET) is the component of the Space Shuttle launch vehicle that contains the liquid hydrogen fuel and liquid oxygen oxidizer." Nowhere in your analysis above have you considered that. The laws of physics and chemistry cannot be defeated, it is only economics that you can meddle with, joules per dollar. I have to tell you honestly that you'll never convince an aeronautical engineer of your quick fix, you've left out far too much reality.
From: Robert Clark on 4 May 2010 14:52 On May 4, 2:28 pm, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "Robert Clark" <rgregorycl...(a)yahoo.com> wrote in message > > news:01ac8580-fa1e-451b-9c77-2543bb3e163a(a)o11g2000yqj.googlegroups.com... > On May 3, 6:31 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > > > > > No matter which way you slice it, lifting a mass against gravity > > will give it potential energy to fall again. Putting it in orbit means > > giving it kinetic energy as well. During re-entry both the KE and > > PE are lost as heat, which is why all vehicles designed for re-entry > > have heat shields. So at the end of the excursion, with energy > > being a conserved quantity, all of the energy in the fuel has been > > converted to heat which is then radiated into space. > > Your problem isn't to find a trajectory, it is to find how to put > > mass into orbit at minimum cost. That is, find joules per dollar > > for the type of fuels and oxidants and the technology available, > > whether it is kerosene-oxygen, hydrogen-oxygen, old rubber tyres, > > nitromethane for "Top Fuel" drag racing or nitro-glycerine! > > ... > > Nowhere in your analysis above have you considered that. > > > The laws of physics and chemistry cannot be defeated, it is only economics > > that you can meddle with, joules per dollar. I have to tell you honestly > > that you'll never convince an aeronautical engineer of your quick fix, > > you've left out far too much reality. > > The advantage of using kerosene <SNIP> > ======================================= > You have not addressed the issue, snipping won't make it go away > no matter how much you wish it would, and I can snip too. > > Airliners burn two tons of fuel on take-off and throttle back to > cruise. They have the advantage of using atmospheric oxygen > up to 50,000 feet (10 miles) and normally cruise economically > at 30,000 feet where the air is thin enough to reduce drag and > thick enough to breathe (they are pressurised to 8000 feet, > compressors force air into the cabin). If you've ever flown > you'll know your ears pop. > But to reach the ISS an altitude of 200 miles is needed, so an > oxidant needs to be lifted along with the fuel for the other 190 > miles. > http://en.wikipedia.org/wiki/Space_Shuttle_external_tank > "A Space Shuttle External Tank (ET) is the component of the Space Shuttle > launch vehicle that contains the liquid hydrogen fuel and liquid oxygen > oxidizer." > > Nowhere in your analysis above have you considered that. > > The laws of physics and chemistry cannot be defeated, it is only economics > that you can meddle with, joules per dollar. I have to tell you honestly > that you'll never convince an aeronautical engineer of your quick fix, > you've left out far too much reality. What are you arguing? That a SSTO only can be accomplished by using an airbeathing method? Bob Clark
From: Androcles on 4 May 2010 14:58 "Robert Clark" <rgregoryclark(a)yahoo.com> wrote in message news:dd0fe185-f5ab-43ae-90f5-d094332fdf3f(a)q32g2000yqb.googlegroups.com... On May 4, 2:28 pm, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "Robert Clark" <rgregorycl...(a)yahoo.com> wrote in message > > news:01ac8580-fa1e-451b-9c77-2543bb3e163a(a)o11g2000yqj.googlegroups.com... > On May 3, 6:31 am, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > > > > > No matter which way you slice it, lifting a mass against gravity > > will give it potential energy to fall again. Putting it in orbit means > > giving it kinetic energy as well. During re-entry both the KE and > > PE are lost as heat, which is why all vehicles designed for re-entry > > have heat shields. So at the end of the excursion, with energy > > being a conserved quantity, all of the energy in the fuel has been > > converted to heat which is then radiated into space. > > Your problem isn't to find a trajectory, it is to find how to put > > mass into orbit at minimum cost. That is, find joules per dollar > > for the type of fuels and oxidants and the technology available, > > whether it is kerosene-oxygen, hydrogen-oxygen, old rubber tyres, > > nitromethane for "Top Fuel" drag racing or nitro-glycerine! > > ... > > Nowhere in your analysis above have you considered that. > > > The laws of physics and chemistry cannot be defeated, it is only > > economics > > that you can meddle with, joules per dollar. I have to tell you honestly > > that you'll never convince an aeronautical engineer of your quick fix, > > you've left out far too much reality. > > The advantage of using kerosene <SNIP> > ======================================= > You have not addressed the issue, snipping won't make it go away > no matter how much you wish it would, and I can snip too. > > Airliners burn two tons of fuel on take-off and throttle back to > cruise. They have the advantage of using atmospheric oxygen > up to 50,000 feet (10 miles) and normally cruise economically > at 30,000 feet where the air is thin enough to reduce drag and > thick enough to breathe (they are pressurised to 8000 feet, > compressors force air into the cabin). If you've ever flown > you'll know your ears pop. > But to reach the ISS an altitude of 200 miles is needed, so an > oxidant needs to be lifted along with the fuel for the other 190 > miles. > http://en.wikipedia.org/wiki/Space_Shuttle_external_tank > "A Space Shuttle External Tank (ET) is the component of the Space Shuttle > launch vehicle that contains the liquid hydrogen fuel and liquid oxygen > oxidizer." > > Nowhere in your analysis above have you considered that. > > The laws of physics and chemistry cannot be defeated, it is only economics > that you can meddle with, joules per dollar. I have to tell you honestly > that you'll never convince an aeronautical engineer of your quick fix, > you've left out far too much reality. What are you arguing? ============================================= I've just explained what I'm arguing, do you want me to paste it again? Ok, I'll paste it again. Airliners burn two tons of fuel on take-off and throttle back to cruise. They have the advantage of using atmospheric oxygen up to 50,000 feet (10 miles) and normally cruise economically at 30,000 feet where the air is thin enough to reduce drag and thick enough to breathe (they are pressurised to 8000 feet, compressors force air into the cabin). If you've ever flown you'll know your ears pop. But to reach the ISS an altitude of 200 miles is needed, so an oxidant needs to be lifted along with the fuel for the other 190 miles. http://en.wikipedia.org/wiki/Space_Shuttle_external_tank "A Space Shuttle External Tank (ET) is the component of the Space Shuttle launch vehicle that contains the liquid hydrogen fuel and liquid oxygen oxidizer." Nowhere in your analysis above have you considered that. The laws of physics and chemistry cannot be defeated, it is only economics that you can meddle with, joules per dollar. I have to tell you honestly that you'll never convince an aeronautical engineer of your quick fix, you've left out far too much reality.
From: Robert Clark on 4 May 2010 15:07
On May 4, 2:58 pm, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > > ============================================= > I've just explained what I'm arguing, do you want me to paste it again? > Ok, I'll paste it again. > > Airliners burn two tons of fuel on take-off and throttle back to > cruise. They have the advantage of using atmospheric oxygen > up to 50,000 feet (10 miles) and normally cruise economically > at 30,000 feet where the air is thin enough to reduce drag and > thick enough to breathe (they are pressurised to 8000 feet, > compressors force air into the cabin). If you've ever flown > you'll know your ears pop. > But to reach the ISS an altitude of 200 miles is needed, so an > oxidant needs to be lifted along with the fuel for the other 190 > miles. > http://en.wikipedia.org/wiki/Space_Shuttle_external_tank > "A Space Shuttle External Tank (ET) is the component of the Space Shuttle > launch vehicle that contains the liquid hydrogen fuel and liquid oxygen > oxidizer." > > Nowhere in your analysis above have you considered that. > > The laws of physics and chemistry cannot be defeated, it is only economics > that you can meddle with, joules per dollar. I have to tell you honestly > that you'll never convince an aeronautical engineer of your quick fix, > you've left out far too much reality. What is the point of your argument? You're clearly not saying no rocket whether singly or multistaged can reach orbit. So are saying a single stage rocket can not reach orbit? Bob Clark |