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#1




Cheap Access to Space
There has been lots of interest in Scramjets because of their
potential to lower the cost of access to space, or Single Stage to Orbit as a means of lowering cost of access to space. Back in 1972, it was estimated that the Space Shuttle would cost as little as $455 per kg. In 2007 dollars, this works out to $2,188.05 per kg. And that was considered good. Below, I outline my theory as to how we can achieve $600 per kg today, which would work out to $125 in 2007 dollars or better than the space shuttle was supposed to be. If you can get costs below $600 per kg in today's dollars, you can launch 25,000 kg of payload for $15 million and thus sell 20 tickets to space for $15 million, or tickets are for sale at $750,000 per ticket. That seems reasonable. (The Space Shuttle has a payload of approximately 25,000 kg). I will assume the first stage goes straight up and has an imparted acceleration of 3 g's, e.g. an actual acceleration of 2 g's. I will also assume it takes 9700 m/s to reach orbit from the ground (orbital velocity is somewhat less but we must contribute both kinetic and potential energy to achieve a circular orbit). I will also assume we have a payload of 25,000 kg and the fuels used are liquid hydrogen (LH2) and liquid oxygen (LOX). I assume hydrogen costs $3.00 per kg and oxygen costs $0.20 per kg. These seem reasonable. Finally I make one small blunder: the cost of the vehicle without fuel is just $100 times the weight in kilograms. This seems reasonable if it is made of aluminum alloy, but in practice it takes a lot of energy to machine rocket parts from raw materials, and all this energy costs money. Nevertheless $100/kg is a ballpark figure (note this low cost precludes the use of titanium, baring any new technologies. Also we might need to circulate a fluid throughout the skin of the first stage to keep it from melting). First, let's look at a 3stage throwaway system for comparison with my proposal. A typical rocket is 71% propellant and has 15% payload, e.g. is 14% empty weight. This corresponds with a mass ratio of 3.45 which seems reasonable. Stage 1 : 71% propellant, 15% payload, 14% empty. Imparted delta V is 4330 m/s but only 2881.2 m/s is realized due to gravity losses (we're flying straight up). We assumed an exaust velocity of 3500 m/s which is reasonable for LH2LOX at sea level. Stage 2 : 71% propellant, 15% payload, 14% empty. A deltaV of 5447 m/ s is realized. We assume an exaust velocity of 4400 m/s which is reasonable for LH2LOX in vacuum. Stage 3 :1373 m/s is needed to reach our 9700 m/s figure. This leads to a needed mass ratio of 1.366 e.g. 26.8% propellant, 14% empty, 59.2% payload. Now using this figure as a baseline, we will see how my proposal stands. The payload is 0.15 * 0.15 * 0.592 = 1.332%. Since we state that we have a payload of 25,000 kg, we deduce the vehicle must have a mass of 1,876,877 kg at liftoff. Let's get a minimum estimate of how much it costs, though. To do this, we take the liftoff mass of 1,876,877 kg and multiply by 14% to get the empty weight of just the first stage. At $100 / kg, just the first stage costs $26,276,276. Using this method, we can get to space, but it costs over $25 million to reach orbit. That is, it costs over $1000 per kg to reach orbit. Now for my proposal. I propose, decrease the payload fraction, thus increasing the mass of the vehicle, on purpose. Why you might ask? Because the first stage is not reusable in the above system. But if the first stage is a rocketplane that flies to above 40 km and then deploys a 2stage rocket system that boosts to orbit, instead of a throwaway system, then it is true the weight of the wings adds to the total weight of the system, but the first stage, which is the most massive part of the vehicle, becomes reusable. I assume the first stage is a rocketplane with an empty mass of 42% (including wings, ballpark what the Concord's empty weight is). We still want the rocketplane to have 15% payload, and this leaves us with only 43% rocket propellant. Using an exaust velocity of 3500 m/s again, we see the first stage can impart only a deltaV of 1967 m/s. Now we are taking off vertically (the firststage lands horizontally). 1967 m/s is the vertical velocity we'd achieve if there were no gravity losses. It's mach 5.73 at sea level, but we'll be over 40 km in altitude by this point, so "hypersonic" stage separation is a non issue. Again we assume an imparted acceleration of 3 g's (29.4 m/s^2). The first stage boost thus lasts only 66.9 seconds. Actual velocity achieved will be 1311.24 m/s (2 g's times 66.9 seconds). We achieve an altitude of 0.5 * 2g * t * t = 43861 m or just over 40 km. We are cruising upwords at 1311.24 m/s  say 1300 m/s  at 43,861 m altitude. That is 143,901 ft. Way high up. Now to achieve orbit, we need a deltaV of 9700 m/s. 9700  1300 = 8400 m/s. That's where the space plane deploys its 2stage rocket system. In 2 stages we must achieve a deltaV of 8400 m/s. Stage 2 : 71% propellant, 15% payload, 14% empty weight. Using an exaust velocity of 4400 m/s (in vacuum), we can achieve a deltaV 5447 m/s via Stage 2.. Stage 3 : to reach 9700 m/s we need a deltaV of 2953 m/s. That is, a mass ratio of 1.96 or 49%. If it's 14% empty weight, we can have a payload of 37%. Putting it all together: 0.37 * 0.15 * 0.15 = 0.008325. That is to say, we now have a payload fraction that has been reduced, to only 0.8325%. That sounds low, it's certainly lower than the payload fraction of the disposable 3stage rocket described above. 3,003,003 kg is the takeoff weight needed for 25,000 kg to reach orbit. It's considerably more than the weight of the 3stage throw away (disposable) rocket system, but, let's see how the cost compares! 3.003003e6 * 0.42 = 1261261.26 x $100/kg = $126,126,126 (Not bad! E.g. $ 504,505 / flight at 250 flights) That is to say, the first stage "reusable" space plane costs $126 million. We amortize it over 250 flights, assuming it is good for that many flights. Dividing $126 million by 250, we find the cost of the first stage is only about $500,000 per flight. Compare that to the $25 million cost of the disposable first stage! 3.003003e6 * 0.15 * 0.14 = 63063.063 x $100/kg = $ 6,306,306.3 3.003003e6 * 0.15 * 0.15 * 0.14 = 9459.45945 x $100/kg = $ 945,945.945 Total SHIP cost per flight: 504505 + 6306306.3 + 945945.945 = $7,756,757.245 Dividing by 25,000 kg we find the ship cost is $310/kg Propellant cost. 3.003003e6 * 0.43 = 1 291 291.29 kg 3.003003e6 * 0.15 * 0.71 = 319 819.8195 kg 3.003003e6 * 0.15 * 0.15 * 0.49 = 33 108.108075 kg Total propellant: 1291291.29 + 319819.8195 + 33108.108075 = 1 644 219 kg LH2 : 1644219 * 11800 / 81614 = 237726 * 3.00 USD = $ 713178.0 LOX : 1644219 * 69814 / 81614 = 1406493 * 0.20 USD = $ 281298.6 Total propellant cost: $994476.6 Total mission cost: 994476.6 + 7756757.245 = $ 8 751 233.845 E.g. $350 / kg Thus, if amortizing over 250 flights is reasonable, e.g. if we can actually find 250 customers that need to launch 25,000 kg into space for a mission cost of $15,000,000 (e.g. ticket price of $750,000 for 20 tourists on a 3day mission to space), then including fuel and the cost of the disposable vehicle, we arrive at a total mission cost of around $9.0 million. But there are other costs like human salaries and so on, and providing the payload itself, and profit, so we will round this figure up to $15.0 million per mission. Compare this cost to the firststage cost of $25.0 million for a throw away system. Thus, I have shown that a reusable firststage, despite having a heavy wing weight, can substantially reduce the permission and perkg payload cost. Even though the payload fraction is substantially reduced, and  without using singlestagetoorbit or scramjets, we have found a way to lower the cost of access to space, within the model used (e.g. $100/ kg empty cost etc.), to just $600 / kg which is marketable. Anyone care to comment or check my numbers? Your feedback is appreciated! 
Ads 
#2




Cheap Access to Space
On Fri, 14 Dec 2007 23:23:55 0800 (PST), in a place far, far away,
made the phosphor on my monitor glow in such a way as to indicate that: There has been lots of interest in Scramjets because of their potential to lower the cost of access to space, or Single Stage to Orbit as a means of lowering cost of access to space. Yes, a lot of mistaken interest in them. Scramjets, or any other airbreather, are unlikely to be the solution to lowcost launch. 
#3




Cheap Access to Space
On 15 Dec, 07:23, wrote:
There has been lots of interest in Scramjets because of their potential to lower the cost of access to space, or Single Stage to Orbit as a means of lowering cost of access to space. Back in 1972, it was estimated that the Space Shuttle would cost as little as $455 per kg. In 2007 dollars, this works out to $2,188.05 per kg. And that was considered good. Below, I outline my theory as to how we can achieve $600 per kg today, which would work out to $125 in 2007 dollars or better than the space shuttle was supposed to be. If you can get costs below $600 per kg in today's dollars, you can launch 25,000 kg of payload for $15 million and thus sell 20 tickets to space for $15 million, or tickets are for sale at $750,000 per ticket. That seems reasonable. (The Space Shuttle has a payload of approximately 25,000 kg). I will assume the first stage goes straight up and has an imparted acceleration of 3 g's, e.g. an actual acceleration of 2 g's. I will also assume it takes 9700 m/s to reach orbit from the ground (orbital velocity is somewhat less but we must contribute both kinetic and potential energy to achieve a circular orbit). I will also assume we have a payload of 25,000 kg and the fuels used are liquid hydrogen (LH2) and liquid oxygen (LOX). I assume hydrogen costs $3.00 per kg and oxygen costs $0.20 per kg. These seem reasonable. Finally I make one small blunder: the cost of the vehicle without fuel is just $100 times the weight in kilograms. This seems reasonable if it is made of aluminum alloy, but in practice it takes a lot of energy to machine rocket parts from raw materials, and all this energy costs money. Nevertheless $100/kg is a ballpark figure (note this low cost precludes the use of titanium, baring any new technologies. Also we might need to circulate a fluid throughout the skin of the first stage to keep it from melting). First, let's look at a 3stage throwaway system for comparison with my proposal. A typical rocket is 71% propellant and has 15% payload, e.g. is 14% empty weight. This corresponds with a mass ratio of 3.45 which seems reasonable. Stage 1 : 71% propellant, 15% payload, 14% empty. Imparted delta V is 4330 m/s but only 2881.2 m/s is realized due to gravity losses (we're flying straight up). We assumed an exaust velocity of 3500 m/s which is reasonable for LH2LOX at sea level. Stage 2 : 71% propellant, 15% payload, 14% empty. A deltaV of 5447 m/ s is realized. We assume an exaust velocity of 4400 m/s which is reasonable for LH2LOX in vacuum. Stage 3 :1373 m/s is needed to reach our 9700 m/s figure. This leads to a needed mass ratio of 1.366 e.g. 26.8% propellant, 14% empty, 59.2% payload. Now using this figure as a baseline, we will see how my proposal stands. The payload is 0.15 * 0.15 * 0.592 = 1.332%. Since we state that we have a payload of 25,000 kg, we deduce the vehicle must have a mass of 1,876,877 kg at liftoff. Let's get a minimum estimate of how much it costs, though. To do this, we take the liftoff mass of 1,876,877 kg and multiply by 14% to get the empty weight of just the first stage. At $100 / kg, just the first stage costs $26,276,276. Using this method, we can get to space, but it costs over $25 million to reach orbit. That is, it costs over $1000 per kg to reach orbit. Now for my proposal. I propose, decrease the payload fraction, thus increasing the mass of the vehicle, on purpose. Why you might ask? Because the first stage is not reusable in the above system. But if the first stage is a rocketplane that flies to above 40 km and then deploys a 2stage rocket system that boosts to orbit, instead of a throwaway system, then it is true the weight of the wings adds to the total weight of the system, but the first stage, which is the most massive part of the vehicle, becomes reusable. I assume the first stage is a rocketplane with an empty mass of 42% (including wings, ballpark what the Concord's empty weight is). We still want the rocketplane to have 15% payload, and this leaves us with only 43% rocket propellant. Using an exaust velocity of 3500 m/s again, we see the first stage can impart only a deltaV of 1967 m/s. Now we are taking off vertically (the firststage lands horizontally). 1967 m/s is the vertical velocity we'd achieve if there were no gravity losses. It's mach 5.73 at sea level, but we'll be over 40 km in altitude by this point, so "hypersonic" stage separation is a non issue. Again we assume an imparted acceleration of 3 g's (29.4 m/s^2). The first stage boost thus lasts only 66.9 seconds. Actual velocity achieved will be 1311.24 m/s (2 g's times 66.9 seconds). We achieve an altitude of 0.5 * 2g * t * t = 43861 m or just over 40 km. We are cruising upwords at 1311.24 m/s  say 1300 m/s  at 43,861 m altitude. That is 143,901 ft. Way high up. Now to achieve orbit, we need a deltaV of 9700 m/s. 9700  1300 = 8400 m/s. That's where the space plane deploys its 2stage rocket system. In 2 stages we must achieve a deltaV of 8400 m/s. Stage 2 : 71% propellant, 15% payload, 14% empty weight. Using an exaust velocity of 4400 m/s (in vacuum), we can achieve a deltaV 5447 m/s via Stage 2.. Stage 3 : to reach 9700 m/s we need a deltaV of 2953 m/s. That is, a mass ratio of 1.96 or 49%. If it's 14% empty weight, we can have a payload of 37%. Putting it all together: 0.37 * 0.15 * 0.15 = 0.008325. That is to say, we now have a payload fraction that has been reduced, to only 0.8325%. That sounds low, it's certainly lower than the payload fraction of the disposable 3stage rocket described above. 3,003,003 kg is the takeoff weight needed for 25,000 kg to reach orbit. It's considerably more than the weight of the 3stage throw away (disposable) rocket system, but, let's see how the cost compares! 3.003003e6 * 0.42 = 1261261.26 x $100/kg = $126,126,126 (Not bad! E.g. $ 504,505 / flight at 250 flights) That is to say, the first stage "reusable" space plane costs $126 million. We amortize it over 250 flights, assuming it is good for that many flights. Dividing $126 million by 250, we find the cost of the first stage is only about $500,000 per flight. Compare that to the $25 million cost of the disposable first stage! 3.003003e6 * 0.15 * 0.14 = 63063.063 x $100/kg = $ 6,306,306.3 3.003003e6 * 0.15 * 0.15 * 0.14 = 9459.45945 x $100/kg = $ 945,945.945 Total SHIP cost per flight: 504505 + 6306306.3 + 945945.945 = $7,756,757.245 Dividing by 25,000 kg we find the ship cost is $310/kg Propellant cost. 3.003003e6 * 0.43 = 1 291 291.29 kg 3.003003e6 * 0.15 * 0.71 = 319 819.8195 kg 3.003003e6 * 0.15 * 0.15 * 0.49 = 33 108.108075 kg Total propellant: 1291291.29 + 319819.8195 + 33108.108075 = 1 644 219 kg LH2 : 1644219 * 11800 / 81614 = 237726 * 3.00 USD = $ 713178.0 LOX : 1644219 * 69814 / 81614 = 1406493 * 0.20 USD = $ 281298.6 Total propellant cost: $994476.6 Total mission cost: 994476.6 + 7756757.245 = $ 8 751 233.845 E.g. $350 / kg Thus, if amortizing over 250 flights is reasonable, e.g. if we can actually find 250 customers that need to launch 25,000 kg into space for a mission cost of $15,000,000 (e.g. ticket price of $750,000 for 20 tourists on a 3day mission to space), then including fuel and the cost of the disposable vehicle, we arrive at a total mission cost of around $9.0 million. But there are other costs like human salaries and so on, and providing the payload itself, and profit, so we will round this figure up to $15.0 million per mission. Compare this cost to the firststage cost of $25.0 million for a throw away system. Thus, I have shown that a reusable firststage, despite having a heavy wing weight, can substantially reduce the permission and perkg payload cost. Even though the payload fraction is substantially reduced, and  without using singlestagetoorbit or scramjets, we have found a way to lower the cost of access to space, within the model used (e.g. $100/ kg empty cost etc.), to just $600 / kg which is marketable. Anyone care to comment or check my numbers? Your feedback is appreciated! The number of flights you amorize something over depends on the demand there is in the system. We have two possibilities : Hypersonic aircraft or 2STO. Neither is proven as an answer to low cost access. Costs for anything are a function of supply and demand. Put the demand up and unit costs tend to fall. Henry Ford proved this with car construction. It could well be that the answer to low cost space access is simply to mass produce expendables  in short make them as cheap Kg for Kg as cars and not worry about any alternative technology. It is not intuitively obvious that either route (hypersonics or reusable rockets) will produce a lower cost than the "Ford" route. In point of fact the energy cost of fabricating rockets is small ,as is the fuel cost. The main cost is in the highly skilled precision engineering required + checking and testing. The fundamental reason why costs are high is that demand is low. Costs will therefore be high regardless of the technology. Rand does not seem to appreciate this. I would still like to ask him what technology he would prefer, but all I get is abuse.  Ian Parker 
#4




Cheap Access to Space

#5




Cheap Access to Space
On Sat, 15 Dec 2007 09:00:37 0800, in a place far, far away, John
Schilling made the phosphor on my monitor glow in such a way as to indicate that: On Fri, 14 Dec 2007 23:23:55 0800 (PST), wrote: There has been lots of interest in Scramjets because of their potential to lower the cost of access to space, or Single Stage to Orbit as a means of lowering cost of access to space. "Has been", past tense. That interest went away when everyone realized that the hypersonics people didn't have a clue how to build a scramjet that would be useful for space launch. As John Hare put it, there's an extra "r" in scramjet. Anyone care to comment or check my numbers? Your feedback is appreciated! I didn't see anything wrong with them on a quick look, but your numbers are based on the assumption that someone comes up with a useful scramjet. Actually, it looked to me like he was proposing an allrocket system. 
#6




Cheap Access to Space
Your numbers are good enough, but China already offers "Cheap Access
to Space", and at not costing ten cents on our badly inflated dollar, especially CATS worthy if China is officially in charge of doing our moon and of controlling the moon's L1 usage. Of course we could always use those fully prooftested and 100% reliable methods of using our extremely LEO efficient Saturn, such as for otherwise having gotten nearly 50 tonnes into a close orbit of our moon within 3 days, and all of such accomplished with a mere 60:1 ratio of rocket per payload, as well as for having to deal with a nearly 30% inert GLOW at that. As far as we know, there's still nothing of such flybyrocket capability available that's hardly half as good.  Brad Guth wrote: There has been lots of interest in Scramjets because of their potential to lower the cost of access to space, or Single Stage to Orbit as a means of lowering cost of access to space. Back in 1972, it was estimated that the Space Shuttle would cost as little as $455 per kg. In 2007 dollars, this works out to $2,188.05 per kg. And that was considered good. Below, I outline my theory as to how we can achieve $600 per kg today, which would work out to $125 in 2007 dollars or better than the space shuttle was supposed to be. If you can get costs below $600 per kg in today's dollars, you can launch 25,000 kg of payload for $15 million and thus sell 20 tickets to space for $15 million, or tickets are for sale at $750,000 per ticket. That seems reasonable. (The Space Shuttle has a payload of approximately 25,000 kg). I will assume the first stage goes straight up and has an imparted acceleration of 3 g's, e.g. an actual acceleration of 2 g's. I will also assume it takes 9700 m/s to reach orbit from the ground (orbital velocity is somewhat less but we must contribute both kinetic and potential energy to achieve a circular orbit). I will also assume we have a payload of 25,000 kg and the fuels used are liquid hydrogen (LH2) and liquid oxygen (LOX). I assume hydrogen costs $3.00 per kg and oxygen costs $0.20 per kg. These seem reasonable. Finally I make one small blunder: the cost of the vehicle without fuel is just $100 times the weight in kilograms. This seems reasonable if it is made of aluminum alloy, but in practice it takes a lot of energy to machine rocket parts from raw materials, and all this energy costs money. Nevertheless $100/kg is a ballpark figure (note this low cost precludes the use of titanium, baring any new technologies. Also we might need to circulate a fluid throughout the skin of the first stage to keep it from melting). First, let's look at a 3stage throwaway system for comparison with my proposal. A typical rocket is 71% propellant and has 15% payload, e.g. is 14% empty weight. This corresponds with a mass ratio of 3.45 which seems reasonable. Stage 1 : 71% propellant, 15% payload, 14% empty. Imparted delta V is 4330 m/s but only 2881.2 m/s is realized due to gravity losses (we're flying straight up). We assumed an exaust velocity of 3500 m/s which is reasonable for LH2LOX at sea level. Stage 2 : 71% propellant, 15% payload, 14% empty. A deltaV of 5447 m/ s is realized. We assume an exaust velocity of 4400 m/s which is reasonable for LH2LOX in vacuum. Stage 3 :1373 m/s is needed to reach our 9700 m/s figure. This leads to a needed mass ratio of 1.366 e.g. 26.8% propellant, 14% empty, 59.2% payload. Now using this figure as a baseline, we will see how my proposal stands. The payload is 0.15 * 0.15 * 0.592 = 1.332%. Since we state that we have a payload of 25,000 kg, we deduce the vehicle must have a mass of 1,876,877 kg at liftoff. Let's get a minimum estimate of how much it costs, though. To do this, we take the liftoff mass of 1,876,877 kg and multiply by 14% to get the empty weight of just the first stage. At $100 / kg, just the first stage costs $26,276,276. Using this method, we can get to space, but it costs over $25 million to reach orbit. That is, it costs over $1000 per kg to reach orbit. Now for my proposal. I propose, decrease the payload fraction, thus increasing the mass of the vehicle, on purpose. Why you might ask? Because the first stage is not reusable in the above system. But if the first stage is a rocketplane that flies to above 40 km and then deploys a 2stage rocket system that boosts to orbit, instead of a throwaway system, then it is true the weight of the wings adds to the total weight of the system, but the first stage, which is the most massive part of the vehicle, becomes reusable. I assume the first stage is a rocketplane with an empty mass of 42% (including wings, ballpark what the Concord's empty weight is). We still want the rocketplane to have 15% payload, and this leaves us with only 43% rocket propellant. Using an exaust velocity of 3500 m/s again, we see the first stage can impart only a deltaV of 1967 m/s. Now we are taking off vertically (the firststage lands horizontally). 1967 m/s is the vertical velocity we'd achieve if there were no gravity losses. It's mach 5.73 at sea level, but we'll be over 40 km in altitude by this point, so "hypersonic" stage separation is a non issue. Again we assume an imparted acceleration of 3 g's (29.4 m/s^2). The first stage boost thus lasts only 66.9 seconds. Actual velocity achieved will be 1311.24 m/s (2 g's times 66.9 seconds). We achieve an altitude of 0.5 * 2g * t * t = 43861 m or just over 40 km. We are cruising upwords at 1311.24 m/s  say 1300 m/s  at 43,861 m altitude. That is 143,901 ft. Way high up. Now to achieve orbit, we need a deltaV of 9700 m/s. 9700  1300 = 8400 m/s. That's where the space plane deploys its 2stage rocket system. In 2 stages we must achieve a deltaV of 8400 m/s. Stage 2 : 71% propellant, 15% payload, 14% empty weight. Using an exaust velocity of 4400 m/s (in vacuum), we can achieve a deltaV 5447 m/s via Stage 2.. Stage 3 : to reach 9700 m/s we need a deltaV of 2953 m/s. That is, a mass ratio of 1.96 or 49%. If it's 14% empty weight, we can have a payload of 37%. Putting it all together: 0.37 * 0.15 * 0.15 = 0.008325. That is to say, we now have a payload fraction that has been reduced, to only 0.8325%. That sounds low, it's certainly lower than the payload fraction of the disposable 3stage rocket described above. 3,003,003 kg is the takeoff weight needed for 25,000 kg to reach orbit. It's considerably more than the weight of the 3stage throw away (disposable) rocket system, but, let's see how the cost compares! 3.003003e6 * 0.42 = 1261261.26 x $100/kg = $126,126,126 (Not bad! E.g. $ 504,505 / flight at 250 flights) That is to say, the first stage "reusable" space plane costs $126 million. We amortize it over 250 flights, assuming it is good for that many flights. Dividing $126 million by 250, we find the cost of the first stage is only about $500,000 per flight. Compare that to the $25 million cost of the disposable first stage! 3.003003e6 * 0.15 * 0.14 = 63063.063 x $100/kg = $ 6,306,306.3 3.003003e6 * 0.15 * 0.15 * 0.14 = 9459.45945 x $100/kg = $ 945,945.945 Total SHIP cost per flight: 504505 + 6306306.3 + 945945.945 = $7,756,757.245 Dividing by 25,000 kg we find the ship cost is $310/kg Propellant cost. 3.003003e6 * 0.43 = 1 291 291.29 kg 3.003003e6 * 0.15 * 0.71 = 319 819.8195 kg 3.003003e6 * 0.15 * 0.15 * 0.49 = 33 108.108075 kg Total propellant: 1291291.29 + 319819.8195 + 33108.108075 = 1 644 219 kg LH2 : 1644219 * 11800 / 81614 = 237726 * 3.00 USD = $ 713178.0 LOX : 1644219 * 69814 / 81614 = 1406493 * 0.20 USD = $ 281298.6 Total propellant cost: $994476.6 Total mission cost: 994476.6 + 7756757.245 = $ 8 751 233.845 E.g. $350 / kg Thus, if amortizing over 250 flights is reasonable, e.g. if we can actually find 250 customers that need to launch 25,000 kg into space for a mission cost of $15,000,000 (e.g. ticket price of $750,000 for 20 tourists on a 3day mission to space), then including fuel and the cost of the disposable vehicle, we arrive at a total mission cost of around $9.0 million. But there are other costs like human salaries and so on, and providing the payload itself, and profit, so we will round this figure up to $15.0 million per mission. Compare this cost to the firststage cost of $25.0 million for a throw away system. Thus, I have shown that a reusable firststage, despite having a heavy wing weight, can substantially reduce the permission and perkg payload cost. Even though the payload fraction is substantially reduced, and  without using singlestagetoorbit or scramjets, we have found a way to lower the cost of access to space, within the model used (e.g. $100/ kg empty cost etc.), to just $600 / kg which is marketable. Anyone care to comment or check my numbers? Your feedback is appreciated! 
#7




Cheap Access to Space

#8




Cheap Access to Space

#9




Cheap Access to Space
On Dec 15, 12:14 pm, (Rand Simberg)
wrote: On Sat, 15 Dec 2007 09:00:37 0800, in a place far, far away, John Schilling made the phosphor on my monitor glow in such a way as to indicate that: On Fri, 14 Dec 2007 23:23:55 0800 (PST), wrote: There has been lots of interest in Scramjets because of their potential to lower the cost of access to space, or Single Stage to Orbit as a means of lowering cost of access to space. "Has been", past tense. That interest went away when everyone realized that the hypersonics people didn't have a clue how to build a scramjet that would be useful for space launch. As John Hare put it, there's an extra "r" in scramjet. Anyone care to comment or check my numbers? Your feedback is appreciated! I didn't see anything wrong with them on a quick look, but your numbers are based on the assumption that someone comes up with a useful scramjet. Actually, it looked to me like he was proposing an allrocket system. Yes, it does look like an allrocket system. However, I saw the word scramjet and didn't bother reading further until your post. There is a lot of potential range for the numbers within the context of an allrocket systemsome better and some worse, IMO. Our approach "wastes" a lot more delta vee, but much more than makes up for this waste in other structural, performance and cost improvements. As a net result of our particular approach, II think the bottomline, overall goal is actually quite modest and achievable, including the "forgotten" factors pointed out by Sylvia. Nothing makes much sense at low traffic levels below 200 flight per year. At higher traffic levels, I think that $500/kg is a quite achievable price, not cost, goal. I think failure to take proper account of traffic level is probably the main factor between the "pessimistic" and "optimistic" posters on this news group. And, as Fred points out, the chickenand egg nature has to be addressed. However, this just makes this problem a problem, not an unsurmountable barrier. Len 
#10




Cheap Access to Space
On Dec 15, 8:34 pm, Sylvia Else wrote:
wrote: That is to say, the first stage "reusable" space plane costs $126 million. We amortize it over 250 flights, assuming it is good for that many flights. Dividing $126 million by 250, we find the cost of the first stage is only about $500,000 per flight. Compare that to the $25 million cost of the disposable first stage! What's the minimum time to perform those 250 missions using a single reusable launcher? You cannot just divide the initial capital cost by the number of flights to get the cost per flight, because you're incurring an opportunity cost on the capital tied up in the launcher. The cost per flight also has to include a component that reflects the risk that the launcher will be lost before completing its 250 missions. This might be covered by insurance, but either way it's a cost that has to be included. Sylvia. Yes these are important cost factors not to be overlookedand we have not overlooked them. As I indicate in my reply to Rand's post elsewhere in this thread, I think the bottomline, overall goal of $500 to $600/kg to LEO in 2007 dolllars is quite modest and achievableincluding your "forgotten" factors. There may be several approaches capable of achieving this goal with an allrocket system; we know of one, at least. Len 
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