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A kerosene-fueled X-33 as a single stage to orbit vehicle.
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#2
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A kerosene-fueled X-33 as a single stage to orbit vehicle.
On 7/14/2011 6:30 AM, Jeff Findley wrote:
All of this silliness is in pursuit of SSTO. Fully reusable TSTO would be far easier to implement than this because it would require no new technologies (i.e. fundamentally new engine) to be developed. I can't see why Lockheed didn't just take their VentureStar design and stick a "V" shaped drop tank on it like there 1960's Star Clipper design was going to use. Since the VentureStar design was only failing marginally as a SSTO, the external tankage wouldn't need be that large, and you would have just eliminated the need for the Shuttle's large SRB's, and would only be losing the fairly cheap drop tank on each mission. Pat |
#3
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A kerosene-fueled X-33 as a single stage to orbit vehicle.
On Jul 14, 12:57*pm, Pat Flannery wrote:
On 7/14/2011 6:30 AM, Jeff Findley wrote: All of this silliness is in pursuit of SSTO. *Fully reusable TSTO would be far easier to implement than this because it would require no new technologies (i.e. fundamentally new engine) to be developed. I can't see why Lockheed didn't just take their VentureStar design and stick a "V" shaped drop tank on it like there 1960's Star Clipper design was going to use. Since the VentureStar design was only failing marginally as a SSTO, the external tankage wouldn't need be that large, and you would have just eliminated the need for the Shuttle's large SRB's, and would only be losing the fairly cheap drop tank on each mission. |
#4
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A kerosene-fueled X-33 as a single stage to orbit vehicle.
On Jul 14, 3:57*pm, Pat Flannery wrote:
On 7/14/2011 6:30 AM, Jeff Findley wrote: All of this silliness is in pursuit of SSTO. *Fully reusable TSTO would be far easier to implement than this because it would require no new technologies (i.e. fundamentally new engine) to be developed. I can't see why Lockheed didn't just take their VentureStar design and stick a "V" shaped drop tank on it like there 1960's Star Clipper design was going to use. Since the VentureStar design was only failing marginally as a SSTO, the external tankage wouldn't need be that large, and you would have just eliminated the need for the Shuttle's large SRB's, and would only be losing the fairly cheap drop tank on each mission. |
#5
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A kerosene-fueled X-33 as a single stage to orbit vehicle.
On 15/07/2011 12:30 AM, Jeff Findley wrote:
In , lid says... sigh It's not a rocket in airbreathing mode. It's some ******* engine that does nothing well. It's not as efficient as a turbofan (likely even a turbojet) aircraft engine when in air- breathing mode and it's not as efficient as a liquid fueled rocket engine when operating in pure rocket mode (LOX from internal tanks). I fail to see how an engine which operates worse than the state of the art in either mode is better than having two separate stages with two separate types of engines on each. All of this silliness is in pursuit of SSTO. Fully reusable TSTO would be far easier to implement than this because it would require no new technologies (i.e. fundamentally new engine) to be developed. It's all about cost per kg payload in orbit. An SSTO, particularly one that takes off and lands horizontally presents considerable operational advantages. While the SABRE engine is more complex than a standard rocket, complexity is removed in other areas - there's no stage separation, for example. It also eliminates a whole class of risks associated with separation, such as collisions between the two parts of the vehicle, partial separation, etc. In any case, it's far from clear that a fully reusable TSTO is so easy to achieve. Getting Skylon to work in practice may prove more difficult than RE think. It may prove impossible. But I don't understand the sheer antagonism towards it evidenced by some in this group. Unless it's a manifestation of a fear that RE will achieve a disruptive technology. http://en.wikipedia.org/wiki/Disruptive_technology Sylvia. |
#7
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A kerosene-fueled X-33 as a single stage to orbit vehicle.
"Pat Flannery" wrote: -- Jeff Findley wrote: Jeff wrote: No, it's mostly the acknowledgment that SABRE is a bleeding edge technology in much the same way as a hypersonic air breathing engine (e.g. NASP and more recent technology demonstrators). We've been down this road more than once, and it's burned us each and every time. Pat wrote: In the case of the NASP/Copper Canyon, the scramjet technology may have been at least partially a chimera, to mislead the Soviets and drive them to the bargaining table. hanson wrote: http://www.physorg.com/news/2011-03-experimental-scramjet-aircraft-flight.html There is this X-51 thing that superceded the Aurora stuff SR-91 (Not 71), http://www.fas.org/irp/mystery/aurora.htm which back in July 1998 stirred up controversy when it went over LA to land at Edwards, producing 2 sonicbooms and showing a pearl-chain-like exhaust vapor trail. These are all apparently descendants and supersonic versions of the 1944 Nazi version of the Buzz bomb http://en.wikipedia.org/wiki/V-1_flying_bomb Price tag for $/Speed though, is not exactly linear... ahahaha... Also, whether that did or not intermesh with Soviet technology or their intents is another story, but it certainly creates great lore and lure... ahahahaha... |
#8
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A kerosene-fueled X-33 as a single stage to orbit vehicle.
In sci.space.history Jeff Findley wrote:
Stage separation is an existing technology that's been in place on the very first orbital launch vehicle. It's at least a fairly well known quantity, especially if you do your stage separation above the bulk of the atmosphere. I'll simply toss some shells from the peanut gallery not meant to suggest favoring one side of the other... And yet even in 2010 (or was it 2009) SpaceX still had their stages bump rick jones -- No need to believe in either side, or any side. There is no cause. There's only yourself. The belief is in your own precision. - Joubert these opinions are mine, all mine; HP might not want them anyway... feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |
#9
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A kerosene-fueled X-33 as a single stage to orbit vehicle.
On 7/15/2011 6:23 AM, Jeff Findley wrote:
No, it's mostly the acknowledgment that SABRE is a bleeding edge technology in much the same way as a hypersonic air breathing engine (e.g. NASP and more recent technology demonstrators). We've been down this road more than once, and it's burned us each and every time. In the case of the NASP/Copper Canyon, the scramjet technology may have been at least partially a chimera, to mislead the Soviets and drive them to the bargaining table. Pat |
#10
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A kerosene-fueled X-33 as a single stage to orbit vehicle.
On 16/07/2011 12:23 AM, Jeff Findley wrote:
In , lid says... On 15/07/2011 12:30 AM, Jeff Findley wrote: In , lid says... sigh It's not a rocket in airbreathing mode. It's some ******* engine that does nothing well. It's not as efficient as a turbofan (likely even a turbojet) aircraft engine when in air- breathing mode and it's not as efficient as a liquid fueled rocket engine when operating in pure rocket mode (LOX from internal tanks). I fail to see how an engine which operates worse than the state of the art in either mode is better than having two separate stages with two separate types of engines on each. All of this silliness is in pursuit of SSTO. Fully reusable TSTO would be far easier to implement than this because it would require no new technologies (i.e. fundamentally new engine) to be developed. It's all about cost per kg payload in orbit. An SSTO, particularly one that takes off and lands horizontally presents considerable operational advantages. Please enumerate the advantages of HTHL over VTVL as they apply to SSTO. At this point in time, I'm simply not convinced that the advantages are worth the cost, especially for intact abort scenarios. With VTVL you have to carry fuel for landing. Of course, you don't have to carry wings, so there's an element of swings and roundabouts. With vertical takeoff you have a period during which the rocket exhaust is impacting a launch pad, which thus has to be protected both from the temperature thereof and the shockwaves therein. In a horizontal takeoff the direction of the exhaust is different, and the time of exposure for any given section of runway is much reduced. A horizontally landing vehicle necessarily has wheels, so after it stops, it can be towed away from the landing area without further complication. A vertically landing vehicle either has to carry wheels as dead-weight, or additional ground equipment is required to allow the landed vehicle to be moved from the landing site. Skylon also uses its own wheels for takeoff, so it can be towed to the takeoff point. Compare with the equipment and time required to get a vertically launched vehicle like the shuttle to the launch site. Both systems would need the ability to abort intact at any point, but I don't see any particular benefit to a VTVL system in that regard. While the SABRE engine is more complex than a standard rocket, complexity is removed in other areas - there's no stage separation, for example. Stage separation is an existing technology that's been in place on the very first orbital launch vehicle. It's at least a fairly well known quantity, especially if you do your stage separation above the bulk of the atmosphere. Stage separation is an existing technology as regards disposable rockets, and for some reusable components of the shuttle. Impact by separation debry is a not-insignificant hazard for the shuttle. Avoiding explosive bolts would perhaps reduce the debry hazard, but would increase the chance of an incomplete separation, which would likely cause loss of vehicle. Stage separation above most of the atmosphere, but with the first stage then returning to the launch site seems a questionable proposition. If the first stage lands somewhere else, then provision has to be made for returning it to the launch site, which increases the operating cost. It also eliminates a whole class of risks associated with separation, such as collisions between the two parts of the vehicle, partial separation, etc. A VTVL SSTO would have the same advantages without the high cost of SABRE development. Perhaps, but who has a VTVL SSTO? In any case, it's far from clear that a fully reusable TSTO is so easy to achieve. Possibly, but so far, no one has tried to build and fly such a vehicle. That's not entirely true. The shuttle was orignally meant to be a fully reusable TSTO. The tank and SRBs were substituted for the first stage due to cost. Now, that was NASA, with intereference being run by the USAF for good measure, so I'll concede that perhaps it could be done for substantially less in the hands of private industry. It's at least on firmer technological ground than SABRE and Skylon, so I'd say the chance of success would be much higher for the reusable TSTO. Getting Skylon to work in practice may prove more difficult than RE think. It may prove impossible. But I don't understand the sheer antagonism towards it evidenced by some in this group. Unless it's a manifestation of a fear that RE will achieve a disruptive technology. No, it's mostly the acknowledgment that SABRE is a bleeding edge technology in much the same way as a hypersonic air breathing engine (e.g. NASP and more recent technology demonstrators). We've been down this road more than once, and it's burned us each and every time. Hypersonic air breathing engines are horribly expensive to test, typically requiring a rocket launch. By contrast, and awful lot of SABRE's development can be done on the ground. Don't get me wrong, I'd really *like* to see Reaction Engines succeed and produce a working, economically viable, launch vehicle. I'm just extremely skeptical due to the inclusion of an engine design which has never been fully tested *and* has not been successfully integrated into an actual vehicle. Aerodynamics is a p.i.t.a. and it will rear its ugly head during the design phase where the engine is integrated into a *real* vehicle. So far, I find the "artist's concept" type drawings of Skylon to be lacking in sufficient aerodynamic detail. In order to provide enough air for the engines at flight conditions, the engine will need to be *much* more integrated into the vehicle aerodynamics than current drawings and renderings suggest. I can't see any reason for thinking that integration is required for there to be enough air. The intakes have a particular size. The airflow speed is known. The design deliberately does NOT integrate the engines with the airframe, because that hugely simplifies development. This should come as no surprise since Reaction Engines is focusing on building a working engine first. The problem is still that of the chicken and egg. Without an engine fully integrated into an actual vehicle, it's awfully hard to test either the engine or the vehicle. Due to the nature of the engine (and the aerodynamics needed for the inlet), the two designs are almost inseparable. The inlets are behind the nose shock. I have to wonder a bit about the shock from the canard, but otherwise I can't see that there'll will be any interaction between the airframe and the intakes when the vehicle is supersonic. The subsonic regime will persumably require some attention, but it's one that's well understood. Sylvia. |
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