Page 3 of 11 FirstFirst 12345 ... LastLast
Results 61 to 90 of 319

Thread: Some proposals for low cost heavy lift launchers.

  1. #61
    Join Date
    Oct 2006
    Posts
    3,767
    Quote Originally Posted by RGClark View Post
    if ....and assuming.....could
    You're not talking about the F9 anymore. Not even slightly. It's yet more of your powerpoint engineering that has very very little to do with reality.

  2. #62
    Join Date
    Feb 2004
    Posts
    1,605
    Quote Originally Posted by Garrison View Post
    And one more thing occurred to me Bob, given the overall weight of a two stage Falcon 9 are you sure you aren't including the upper stage fuel in your calculation?
    No, the upper stage fuel is not included. If you look at the first post in the thread I'm estimating the total mass of the first stage as 300,000 kg with the original Merlin engines. I then give an estimate for what the empty mass and fueled mass would be when the Merlins are exchanged for NK-33's.

    Bob Clark

  3. #63
    Join Date
    Sep 2009
    Posts
    4,138
    Quote Originally Posted by RGClark View Post
    If you let Mp be the mass of the propellant, Me be the mass of the unfueled rocket, which includes both the vehicle itself and the payload, and Mt be the total mass, then since Mt = Me + Mp, you see the mass ratio is Mt/Me = (Me + Mp)/Me = 1 + (Mp/Me). Expressing the mass ratio this way makes it easier to do quick changes on the calculator when you are changing for example the payload and seeing how this changes your delta-V, since you don't have to recalculate the total mass and the propellant mass is staying the same.
    Note also in the calculation I used the NK-33 engine which has a better sea level and vacuum Isp than the Merlin.

    Bob Clark
    So in other words it's no vehicle that has ever existed. You've claimed that the Titan and F9 could serve as expendable SSTO's are you now accepting that isn't so using the actual hardware of those vehicles?

  4. #64
    Join Date
    Sep 2009
    Posts
    4,138
    Couple of other things about your fantasy rocket. The Merlin has been designed to be potentially reusable, has the NK-33? How are you planning to cope with the greatly increased amount of space junk your fantasy rocket would create?
    Also. and this may be a small point but it's been bugging me. The title of this thread is 'Some Proposals For Low Cost Heavy Launchers'. All you've been describing so far are some medium lift options, are we going to see an actual heavy lift proposal?

  5. #65
    Join Date
    Jul 2006
    Posts
    887
    Quote Originally Posted by Garrison View Post
    The title of this thread is 'Some Proposals For Low Cost Heavy Launchers'.
    Maybe by "Heavy Launchers" he means rockets that are heavier than other existing vehicles which provide the same payloads to LEO.

  6. #66
    Join Date
    Sep 2009
    Posts
    754
    Just another thread where Clarke is wasting his and other people's time by posting non viable ideas. This thread is no different than the RP-1, re engined shuttle orbiter. Worse than power point engineering, it is photoshop engineering. Over the years, he has yet come up with a viable, feasible or even physically possible concept.

    The most laughable one was an electric powered launch vehicle that relied on a conductor being strung out to high altitudes supported by balloons. The launch vehicle was to treat this wire like a third rail and use a pantograph device to draw power from it.

    Another inane idea, or was it part of the same as above, was to make a tube with an inflatable structure to hold a vacuum and fly a launch vehicle through the middle of it.

    We aren't dealing with rational here.

  7. #67
    Join Date
    Feb 2004
    Posts
    1,605
    Quote Originally Posted by Garrison View Post
    Couple of other things about your fantasy rocket. The Merlin has been designed to be potentially reusable, has the NK-33? How are you planning to cope with the greatly increased amount of space junk your fantasy rocket would create?
    Also. and this may be a small point but it's been bugging me. The title of this thread is 'Some Proposals For Low Cost Heavy Launchers'. All you've been describing so far are some medium lift options, are we going to see an actual heavy lift proposal?
    The answer to your last question is yes. Actually "heavy lift" as described for example by the Augustine Commision could be taken as 50,000 kg and above. Some have defined "heavy lift" as what the shuttle can lift ca. 25,000 kg. I suppose though you're thinking of heavy lift in regards to what the Ares V could have lifted ca. 100,000 kg and above. I'll give some examples where this is possible as well.

    Bob Clark

  8. #68
    Join Date
    Sep 2009
    Posts
    4,138
    Quote Originally Posted by RGClark View Post
    The answer to your last question is yes. Actually "heavy lift" as described for example by the Augustine Commision could be taken as 50,000 kg and above. Some have defined "heavy lift" as what the shuttle can lift ca. 25,000 kg. I suppose though you're thinking of heavy lift in regards to what the Ares V could have lifted ca. 100,000 kg and above. I'll give some examples where this is possible as well.

    Bob Clark
    First even taking the lowest of the three figures you quote there none of your schemes apply. Second please cite these sources that define heavy lift as 25000kg, and thirdly in your examples please stick to hardware that has actually been used in the configuration you describe, no more mixing and matching of specs from different vehicles to try and make the numbers come out right.
    Last edited by Garrison; 2010-Jul-11 at 05:39 PM. Reason: missing word

  9. #69
    Join Date
    Feb 2004
    Posts
    1,605
    Quote Originally Posted by Garrison View Post
    First even taking the lowest of the three figures you quote there none of your schemes apply. Second please cite these sources that define heavy lift as 25000kg, and thirdly in your examples please stick to hardware that has actually been used in the configuration you describe, no more mixing and matching of specs from different vehicles to try and make the numbers come out right.
    Sorry, but the purpose of this was to describe low cost systems that can do what is desired of heavy lift systems. The lowest cost way of doing that is by combining already existing components. Some later ones I'll show probably will be cheaper than the multi-billion dollar proposals under consideration but will require new hardware.
    In the first post of this thread using two Falcon 9 first stages mated bimese fashion using the most high performance engines available instead of the Merlins, could loft ca. 40,000 kg to orbit. Higher energy density hydrocarbon fuels instead of kerosene could loft 50,000+ kg to LEO using this configuration.
    Small, medium, and heavy lift launch systems had been defined in accordance to the type of launchers that were currently existing. Since the heaviest lift existing launchers such as the Space Shuttle, Ariane 5 and Delta IV Heavy could launch in the range of 25,000 kg to LEO this was regarded as "heavy lift":

    Comparison of heavy lift launch systems.
    http://en.wikipedia.org/wiki/Compari...launch_systems

    What we are really interested in now is the debate on creating what I guess would be more accurately described as "Super Heavy Lift". The Augustine Commission described this as 50,000 kg and above, though most proposals being discussed are focusing on launching 100,000 kg and above.

    I discussed also in this thread the payload capacity of a single Falcon 9 first stage using more high performance engines rather than the Merlins to indicate this could be a true SSTO with quite significant payload, not to indicate this one, single stage would qualify as a heavy lift launcher.


    Bob Clark

  10. #70
    Join Date
    Mar 2006
    Posts
    4,031
    In the first post of this thread using two Falcon 9 first stages mated bimese fashion using the most high performance engines available instead of the Merlins, could loft ca. 40,000 kg to orbit.

    You just don't get it. If you start mixing and throwing together pieces of equipment at random like you're proposing, you won't have a Falcon 9 first stage any more. About all you'll have from the Falcon 9 are the propellant tanks. Second, you've never provided the math to back up your performance claims. They're bogus.

  11. #71
    Join Date
    Feb 2004
    Posts
    1,605
    Quote Originally Posted by Larry Jacks View Post
    In the first post of this thread using two Falcon 9 first stages mated bimese fashion using the most high performance engines available instead of the Merlins, could loft ca. 40,000 kg to orbit.

    You just don't get it. If you start mixing and throwing together pieces of equipment at random like you're proposing, you won't have a Falcon 9 first stage any more. About all you'll have from the Falcon 9 are the propellant tanks. Second, you've never provided the math to back up your performance claims. They're bogus.
    Who cares if it's called the Falcon 9 anymore? The obvious point is that by using more efficient engines than the Merlins you can increase the payload. To maximize your payload to orbit obviously you want the best weight-optimized structures, which the Falcon launchers are good at, AND the most efficient engines, which the Russian engines are the best at.
    For the calculation of the payload in post #1, I was using numbers from this report for the first stage Isp that we might be able to achieve:

    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

    In table 2, it gives some trajectory averaged Isp's assuming that altitude-compensation methods are used. For kerolox, it gives it as 338.3 s. I took a little more conservative value in my calculation and took it as 335 s. For the upper stage Isp I used the fact that high performance vacuum optimized Russian kerolox engines have achieved a vacuum Isp of 360 s. Since I was assuming altitude-compensation I took this value of 360 s for the upper stage, vacuum Isp.


    Bob Clark
    Last edited by RGClark; 2010-Jul-13 at 09:29 AM. Reason: added the fact that the 360 s is for vacuum optimized engines, so altitude-compensation would be needed for ground launch use

  12. #72
    Join Date
    Sep 2009
    Posts
    4,138
    Quote Originally Posted by RGClark View Post
    Sorry, but the purpose of this was to describe low cost systems that can do what is desired of heavy lift systems. The lowest cost way of doing that is by combining already existing components. Some later ones I'll show probably will be cheaper than the multi-billion dollar proposals under consideration but will require new hardware.
    In the first post of this thread using two Falcon 9 first stages mated bimese fashion using the most high performance engines available instead of the Merlins, could loft ca. 40,000 kg to orbit. Higher energy density hydrocarbon fuels instead of kerosene could loft 50,000+ kg to LEO using this configuration.
    Small, medium, and heavy lift launch systems had been defined in accordance to the type of launchers that were currently existing. Since the heaviest lift existing launchers such as the Space Shuttle, Ariane 5 and Delta IV Heavy could launch in the range of 25,000 kg to LEO this was regarded as "heavy lift":

    Comparison of heavy lift launch systems.
    http://en.wikipedia.org/wiki/Compari...launch_systems

    What we are really interested in now is the debate on creating what I guess would be more accurately described as "Super Heavy Lift". The Augustine Commission described this as 50,000 kg and above, though most proposals being discussed are focusing on launching 100,000 kg and above.

    I discussed also in this thread the payload capacity of a single Falcon 9 first stage using more high performance engines rather than the Merlins to indicate this could be a true SSTO with quite significant payload, not to indicate this one, single stage would qualify as a heavy lift launcher.


    Bob Clark
    How about you quote some performance figures from a vehicle that actually uses the NK-33 so we can make a real comparison? Also I have to ask again please explain why no one in the rocket industry, not even SpaceX for whom every dollar counts, have followed your SSTO scheme? Could it just be that when you look at a real rocket rather than a cut and paste of different parts from different vehicles, it just doesn't work? Are you even willing to consider the possibility that SpaceX, Boeing, Lockheed Martin, et al are right and you are wrong?

  13. #73
    Join Date
    Jul 2006
    Posts
    887
    Quote Originally Posted by Garrison View Post
    Could it just be that when you look at a real rocket rather than a cut and paste of different parts from different vehicles, it just doesn't work?
    No, no, that can't be it - keep thinking.

  14. #74
    Join Date
    Jun 2010
    Posts
    652
    Quote Originally Posted by Larry Jacks View Post
    Key fact to remember is that SSTO capable stages imply you can lift more payload to orbit than for multistage rockets not so weight-optimized because the weight savings can go to more payload. In fact it can be multiples times more.

    That is so wrong it isn't even funny. You really need to read up on the ramifications of the rocket equation. No amount of handwaving or "physics of wishful thinking" can get around it. From Wikipedia:

    Examples:

    Assume an exhaust velocity of 4.5 km/s and a Δv of 9.7 km/s (Earth to LEO).

    Single stage to orbit rocket: 1 − e − 9.7 / 4.5 = 0.884, therefore 88.4 % of the initial total mass has to be propellant. The remaining 11.6 % is for the engines, the tank, and the payload. In the case of a space shuttle, it would also include the orbiter.

    Two stage to orbit: suppose that the first stage should provide a Δv of 5.0 km/s; 1 − e − 5.0 / 4.5 = 0.671, therefore 67.1% of the initial total mass has to be propellant. The remaining mass is 32.9 %. After disposing of the first stage, a mass remains equal to this 32.9 %, minus the mass of the tank and engines of the first stage. Assume that this is 8 % of the initial total mass, then 24.9 % remains. The second stage should provide a Δv of 4.7 km/s; 1 − e − 4.7 / 4.5 = 0.648, therefore 64.8% of the remaining mass has to be propellant, which is 16.2 %, and 8.7 % remains for the tank and engines of the second stage, the payload, and in the case of a space shuttle, also the orbiter. Thus together 16.7 % is available for all engines, the tanks, the payload, and the possible orbiter.


    If SSTO were as easy as you imagine, why do you think every booster manufacturer in the world makes multistage rockets? Do you believe they want to make their rockets as expensive as possible? If so, for what reason? You seriously don't know what you're talking about.
    That's a good answer. SSTO is something that seems to obsess some people. I don't understand why. I'm a fan of space guns which would fire an SSTO, but in that case the gun is effectively acting as a 4km/s or so first stage.

  15. #75
    Join Date
    Mar 2006
    Posts
    4,031
    That's a good answer. SSTO is something that seems to obsess some people. I don't understand why. I'm a fan of space guns which would fire an SSTO, but in that case the gun is effectively acting as a 4km/s or so first stage.

    Just like some people obsess over HLVs without first determining whether or not they're needed.

  16. #76
    Join Date
    Sep 2009
    Posts
    4,138
    Quote Originally Posted by whimsyfree View Post
    That's a good answer. SSTO is something that seems to obsess some people. I don't understand why. I'm a fan of space guns which would fire an SSTO, but in that case the gun is effectively acting as a 4km/s or so first stage.
    The two major theoretical advantages to an SSTO are easy of operation, especially if takes off and lands on a runway, and reusability; the idea being that a single SSTO can make enough flights that the saving in build costs offsets the lower payload fraction. Also don't forget that the equations Larry Jacksis quoting there only applies to a conventional chemical rocket system. The only SSTO actually under development uses a different approach:

    Skylon

    As you can see it bears exactly zero resemblance to anything RGClark has been talking about.

  17. #77
    Join Date
    Jul 2002
    Posts
    1,564
    Well. only RGclarc is obsessed with SSTO. the rest of us just wants an RLV.
    Preferably a HOTOL RLV instead of the VTOL variety. or the VTHOL (shuttle style) variety.
    There are no set rule that say an RLV needs to be a SSTO. but it being a SSTO eases the operation of the vehicle. (no re-mating of stages and other issues related to staged vehicles)
    The shuttle successfully demonstrated that a staged RLV is quite possible, but no good economically.
    You only need some basic knowledge about how aircraft is built to realize why the shuttle is somewhat of a kludge.
    A rocket is comparable to a tower, and an aircraft is comparable to a bridge load wise. (Very very simplified explanation. so don't nitpick)
    Demanding that the same structure should act as both a tower and a bridge entails adding mass in different sections of the craft to allow it to cope with two disparate forces at different times. Just like a suspension bridge cannot stand on it's end a high rise building cannot lie on it's side over a chasm without breaking. Adding mass like that eat's into your payload fraction.
    the second item that eat's into your payload fraction is the need to carry all the stuff needed for a horizontal landing. (wings and landing gear)
    if you are going to spend mass on those items you get a better bang for your mass by using them on both ends of the trip. hence the push for HOTOL type of craft. a VTOL may also work feasibly, but it would have a lower payload fraction since landing a VTOL is very propellant intensive. while the HOTOL type can glide in for an un-powered landing.

    The tradespace looks somewhat like this:
    HOTOL trade..jpg


    There are probably loads of other items one could add to either cell on the trade space grid.

  18. #78
    Join Date
    Oct 2006
    Posts
    3,767
    Quote Originally Posted by Antice View Post
    Well. only RGclarc is obsessed with SSTO. the rest of us just wants an RLV.
    I don't care if it's an RLV. I just want access to space to become cheaper, by whatever means necessary.

  19. #79
    Join Date
    Jul 2002
    Posts
    1,564
    Quote Originally Posted by djellison View Post
    I don't care if it's an RLV. I just want access to space to become cheaper, by whatever means necessary.
    There is that. We are still a ways off from making ELV's as cheap as they can theoretically be made. but even at current launch rates a true SSTO RLV has the capability of becoming cheaper than current ELV's can ever hope of being able to.
    ELV's will always be dominated by at least fuel + vehicle construction on cost, while an RLV may actually approach a fuel dominated cost level.

  20. #80
    Join Date
    Sep 2009
    Posts
    754
    Quote Originally Posted by Antice View Post
    There is that. We are still a ways off from making ELV's as cheap as they can theoretically be made. but even at current launch rates a true SSTO RLV has the capability of becoming cheaper than current ELV's can ever hope of being able to.
    ELV's will always be dominated by at least fuel + vehicle construction on cost, while an RLV may actually approach a fuel dominated cost level.
    Fuel doesn't even enter the picture for ELV costs. It is labor and not in the construction but in the operations

  21. #81
    Join Date
    Feb 2004
    Posts
    1,605
    Quote Originally Posted by Garrison View Post
    How about you quote some performance figures from a vehicle that actually uses the NK-33 so we can make a real comparison? Also I have to ask again please explain why no one in the rocket industry, not even SpaceX for whom every dollar counts, have followed your SSTO scheme? Could it just be that when you look at a real rocket rather than a cut and paste of different parts from different vehicles, it just doesn't work? Are you even willing to consider the possibility that SpaceX, Boeing, Lockheed Martin, et al are right and you are wrong?
    Aerojet bought the rights to adapt several of the NK-33's for American use. Orbital Sciences plans to use them on their Taurus 2 launcher. Since NASA gave Orbital a billion dollar contract they must have good confidence the Taurus with the NK-33 engines will work.

    The NK-33 has such good performance it can still deliver good payload to orbit with the Falcon 9 first stage bimese configuration even without the altitude-compensation modifications. See the images below to illustrate how cross-feed fueling will work with the bimese configuration. The first shows both filled with propellant indicated in red. At launch all the engines on both Falcon's will be firing but the propellant will be coming only from the one on the right. The second image shows the right tank being half full since it is supplying all the propellant for this first portion of the flight while the Falcons are mated together. The third image shows all the propellant in the right Falcon expended. After this the right Falcon will be jettisoned. Now the left Falcon will continue on to orbit beginning the second portion of the flight with a full propellant load.
    This illustrates the advantage of the bimese with cross-fueling configuration. You get the high propellant load of using the two Falcon first stages but rather than carrying both dry masses to orbit, you do staging that only requires you to carry one of those dry masses to orbit. That saving in dry mass that has to be carried to orbit can go to carrying more payload.
    We'll calculate now the payload to orbit using the NK-33's instead of the Merlins on the bimese-mated Falcon 9's but using the NK-33's in their standard form, not with aerospike nozzles. Again take the dry mass of the single reconfigured Falcon 9 first stage as 12,726 kg and the propellant load as 285,000 kg for each Falcon. Estimate the payload capacity as 29,000 kg.
    The standard NK-33 has sea level Isp of 297 s, and vacuum Isp of 331 s. For the mated together portion we'll take the average Isp as the midpoint of the sea level and vacuum values, so at 314 s. Actually, it will be higher than this since most of the time is spent at high altitude. At the end of this mated-together portion the total mass of the vehicle will be 2*12,726+285,000+29,000 so the delta-V will be 314*9.8ln(1 + 285,000/(2*12,726+285,000+29,000)) = 1,876 m/s. Then for the upper stage portion of the trip with just one of the Falcon 9's, the mass remaining at the end of this will be 12,726 + 29,000 so the delta-V for this will be 331*9.8ln(1 + 285,000/(12,726 + 29,000)) = 6,676 m/s, for a total delta-V of 8,552 m/s, sufficient for orbit with the 8,500 m/s delta-V requirement I'm taking as required for orbit.
    The 29,000 kg payload would be about the same as the SpaceX Falcon 9 Heavy but would be cheaper in only needing two Falcon 9 first stages instead of three and not requiring the upper stage of the Falcon 9.

    Bob Clark
    Attached Images Attached Images

  22. #82
    Join Date
    Sep 2009
    Posts
    4,138
    Quote Originally Posted by RGClark View Post
    Aerojet bought the rights to adapt several of the NK-33's for American use. Orbital Sciences plans to use them on their Taurus 2 launcher. Since NASA gave Orbital a billion dollar contract they must have good confidence the Taurus with the NK-33 engines will work.
    Bob Clark
    That would be the two stage Taurus II? No one is saying the NK-33 doesn't work, they are saying your belief that you can launch heavier payloads by using the lower stage of a two stage rocket won't work. It's not some technical issue to be worked around, it's the basic physics of rocket flight.

  23. #83
    Join Date
    Mar 2006
    Posts
    4,031
    From Orbital's own factsheet, the Taurus II will be a two or three stage medium lift booster in the Delta II class. It was never designed or intended to be anything more.

    Medium-Class Launch Servic es for the 21st Century

    Taurus II is a two-stage launch vehicle designed to provide responsive, cost-effective, and reliable access to orbit and Earth escape for medium-class payloads weighing up to 7,200 kg. Taurus II is designed to be a highly reliable launcher to meet NASA Category 3 and similar DoD mission success standards, and incorporates flight-proven subsystems to reduce development cost, schedule and risk.

    Low Risk Design
    Taurus II incorporates flight-proven components from leading global suppliers and subsystems already successfully deployed on other Orbital launch vehicles.

    Affordable
    Projected launch services rates represent significant savings over existing medium- and heavy-class launchers, reducing total mission cost.

    Leverages Flight-Proven Technologies
    The Taurus II first stage is powered by dual AJ26-62 engines, with second stage propulsion provided by a Castor 30 solid motor (Castor 120 heritage). An optional N2H4/NTO-fueled orbit raising/trim kit is available and a higher performance 2nd Stage for more mass to orbit is also available.

    Fills Medium-Class Launch Services Gap
    Taurus II fills the service gap between medium-light Minotaur IV-class launch vehicles and heavy-lift Delta IV and Atlas 5 offerings.

  24. #84
    Join Date
    Feb 2004
    Posts
    1,605
    Quote Originally Posted by Garrison View Post
    How about you quote some performance figures from a vehicle that actually uses the NK-33 so we can make a real comparison? Also I have to ask again please explain why no one in the rocket industry, not even SpaceX for whom every dollar counts, have followed your SSTO scheme? Could it just be that when you look at a real rocket rather than a cut and paste of different parts from different vehicles, it just doesn't work? Are you even willing to consider the possibility that SpaceX, Boeing, Lockheed Martin, et al are right and you are wrong?
    Also, it doesn't have to be the NK-33 to use to replace the nine Merlins on the Falcon 9. You could also use the RD-180 which is used on the Atlas V. One would suffice in this case. It is about the same weight as the nine Merlins so you wouldn't get any weight saving, but it does have a slightly better Isp than the NK-33's. So the overall performance might be about the same as when using the NK-33's.


    Bob Clark

  25. #85
    Join Date
    May 2005
    Location
    N.E.Ohio
    Posts
    22,006
    Quote Originally Posted by RGClark View Post
    Also, it doesn't have to be the NK-33 to use to replace the nine Merlins on the Falcon 9. You could also use the RD-180 which is used on the Atlas V. One would suffice in this case.
    And by the time you redesign the Falcon 9 to use an RD-180, you would basically be left with an Atlas V. So; what's the point?

  26. #86
    Join Date
    Feb 2004
    Posts
    1,605
    Quote Originally Posted by Garrison View Post
    How about you quote some performance figures from a vehicle that actually uses the NK-33 so we can make a real comparison? Also I have to ask again please explain why no one in the rocket industry, not even SpaceX for whom every dollar counts, have followed your SSTO scheme? Could it just be that when you look at a real rocket rather than a cut and paste of different parts from different vehicles, it just doesn't work? Are you even willing to consider the possibility that SpaceX, Boeing, Lockheed Martin, et al are right and you are wrong?
    On the Space Show aired on April 22nd there was an interview of Gwynne Shotwell, President of SpaceX where she addressed the question of attempting a SSTO. She said Elon decided to go for their two-stage design because they wanted to get to an operational vehicle quickly and there was more technical and, most importantly, financial risk in attempting an SSTO:

    Broadcast 1348 (Special Edition)
    Aired on April 22nd, 2010
    Guest: Gwynne Shotwell
    http://thespaceshow.com/detail.asp?q=1348

    Keep in mind also they couldn't even be sure they could get the high mass ratio they wound up with on the Falcon 9 first stage until it was actually built.
    There is also the fact they needed an engine for their small launcher the Falcon 1. The NK-33 would have been too heavy and overpowered for the Falcon 1. Since they needed to produce an engine anyway for the Falcon 1, they are able to get the best return on their investment by using it as well on the Falcon 9. They are able to make quite a bit more profit over development and construction costs on the 10 Merlins on the Falcon 9 than on the 1 Merlin on the Falcon 1.
    Also SpaceX wanted to get to operational vehicles quickly. The version of the NK-33's from Aerojet won't be ready until 2011 to be used on Orbital Sciences' Taurus 2 launcher.
    Another interesting fact about the engines chosen for these launchers. SpaceX wanted to get to an operational launcher quickly. Necessarily they didn't have the time and probably not the knowledge to get the highest performance from these engines they were building. Then they needed to optimize their vehicle weight to get acceptable performance from their launcher.
    On the other hand Orbital Sciences did choose the Russian high performance engines, but they also chose Russian manufacturers for the vehicle tanks for their Taurus 2 launcher. These tanks though do not have the good weight optimization as the SpaceX launchers.
    So SpaceX has the good weight optimization for their vehicles, but not the best performance from their engines. And Orbital Sciences has the best performance from their engines but not the best weight optimization for their vehicles.
    To get good SSTO performance you have to use the best weight-optimized vehicles and the best performance engines.


    Bob Clark

  27. #87
    Join Date
    Sep 2009
    Posts
    4,138
    Quote Originally Posted by NEOWatcher View Post
    And by the time you redesign the Falcon 9 to use an RD-180, you would basically be left with an Atlas V. So; what's the point?
    In fact doing Bob's favourite equation for the Atlas V, using the data from here:

    Atlas V 500 Series

    I get

    311*9.8ln(305262/(21173+0))=8132.88m/s

    So despite having an engine with a higher sea level ISP the Atlas V first stage would perform worse than the Falcon 9 as an 'SSTO'. It's almost like ISP was just one factor in the design of a complex machine but that can't be it, I mean we're not talking rocket science here are we? Oh wait...

  28. #88
    Join Date
    Feb 2004
    Posts
    1,605
    Quote Originally Posted by Garrison View Post
    That would be the two stage Taurus II? No one is saying the NK-33 doesn't work, they are saying your belief that you can launch heavier payloads by using the lower stage of a two stage rocket won't work. It's not some technical issue to be worked around, it's the basic physics of rocket flight.
    Remember the method I'm suggesting to launch these large payloads *is* using staging. It's just staging of a different type. It is also a special case of parallel staging, a method quite commonly used to launch large payloads. Parallel staging for example is used on the Shuttle, the Delta IV Heavy, Ariane 5, the proposed Falcon 9 Heavy, etc.
    Several studies have concluded parallel staging using cross-feed fueling can increase your payload to orbit.

    Bob Clark

  29. #89
    Join Date
    Sep 2009
    Posts
    4,138
    Quote Originally Posted by RGClark View Post
    Remember the method I'm suggesting to launch these large payloads *is* using staging. It's just staging of a different type. It is also a special case of parallel staging, a method quite commonly used to launch large payloads. Parallel staging for example is used on the Shuttle, the Delta IV Heavy, Ariane 5, the proposed Falcon 9 Heavy, etc.
    Several studies have concluded parallel staging using cross-feed fueling can increase your payload to orbit.

    Bob Clark
    So after all the nonsense you've moved onto staged rockets, may we take this as a concession that your SSTO plan was unworkable? And your new proposal uses a Falcon 9 first stage as the equivalent of the upper stage so it is still going to be less efficient as a launcher.

  30. #90
    Join Date
    May 2005
    Location
    N.E.Ohio
    Posts
    22,006
    Quote Originally Posted by RGClark View Post
    Several studies have concluded parallel staging using cross-feed fueling can increase your payload to orbit.
    You mean after all the flotsam that you have presented in this thread, it boils down to this?
    What was all that SSTO, and ship redesigning options for?

    So; how about you not waste our time about different engine and rocket design options, and give us an apples to apples comparison of something like an Atlas-V heavy, with and without cross-feeds, and balance that against the modifications necessary to do it?

Similar Threads

  1. Replies: 64
    Last Post: 2017-Jan-28, 06:28 PM
  2. Replies: 2
    Last Post: 2011-Jan-17, 09:28 PM
  3. We should have heavy-lift NOW, and Congressmen support this...
    By Zvezdichko in forum Space Exploration
    Replies: 250
    Last Post: 2010-Aug-20, 08:14 PM
  4. Replies: 0
    Last Post: 2010-Feb-06, 06:50 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •