A kerosene-fueled X-33 as a single stage to orbit vehicle.
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From: Androcles on 9 Apr 2010 09:39 "Richard Casady" <richardcasady(a)earthlink.net> wrote in message news:v43ur5t95hngsqbsj3o2pcbufae805456o(a)4ax.com... > On Thu, 08 Apr 2010 13:41:45 -0800, Pat Flannery <flanner(a)daktel.com> > wrote: > >>and there's a nanotechnology radio receiver > > THat will only work with nano tech waves of energy.You can't seriously > expect to nano the antenna down to where it is tuned to hard hard > gammas and get anything worth while out of the system. > > Casady How about this one getting something worthwhile out of the system? http://www.msfc.nasa.gov/NEWSROOM/news/photos/2002/2002images/retina_m.jpg It seems to work with nano tech waves of energy and no hard hard gammas.
From: Pat Flannery on 9 Apr 2010 13:02 On 4/9/2010 3:20 AM, Richard Casady wrote: > On Thu, 08 Apr 2010 13:41:45 -0800, Pat Flannery<flanner(a)daktel.com> > wrote: > >> and there's a nanotechnology radio receiver > > THat will only work with nano tech waves of energy.You can't seriously > expect to nano the antenna down to where it is tuned to hard hard > gammas and get anything worth while out of the system. Well, a little DARK ENERGY in the system will certainly fix that problem. Like Dr. Who's TARDIS, the impactor may appear very small in our universe, but gigantic internally, with room for plenty of car batteries and a short wave radio station to receive telegraphed commands on what it's supposed to do next. We must learn to think outside of the box with this system, and indeed outside the foolish bounds of sanity when considering its revolutionary capabilities. Pat
From: Robert Clark on 10 Apr 2010 11:29 On Apr 6, 10:38 am, Robert Clark <rgregorycl...(a)yahoo.com> wrote: > On Apr 5, 3:29 pm, Robert Clark <rgregorycl...(a)yahoo.com> wrote: > ... > > Now if we only require an altitude considered space of 100 km and the > > carrier craft already gives us 20 km altitude this could just barely > > give us sufficient delta-V for orbit. This delta-V would also be > > helped by using a "lifting ascent trajectory" mentioned in Day's > > articles: > > > Fire in the sky: the Air Launched Sortie Vehicle of the early 1980s > > (part 1) > > by Dwayne Day > > Monday, February 22, 2010 > >http://www.thespacereview.com/article/1569/1 > > > However, there is a question of the max take-off weight of the B-1, > > and how much of that could be fuel compared to payload. For this > > application used only for a short dash to high altitude at high speed > > were long range would not be needed, so therefore much less fuel load, > > could we strengthen the airframe as done for the 747 carrier craft for > > the shuttle so that B-1A could carry the ca. 270,000 lbs loaded weight > > of the X-33? > > As I mentioned in the section on lifting trajectories in the first > post of this thread, you need a good lift/drag ratio at hypersonic > speeds to get significant propellant savings using a lifting > trajectory. See section IV here: > > Newsgroups: sci.space.policy, sci.astro, sci.physics > From: Robert Clark <rgregorycl...(a)yahoo.com> > Date: Sun, 1 Nov 2009 05:20:13 -0800 (PST) > Subject: A kerosene-fueled X-33 as a single stage to orbit vehicle.http://groups.google.com/group/sci.space.policy/msg/0b8b04a58b08278e?... > > The "Air Launched Sortie" vehicles discussed in Day's articles had > such good ratios. However, for the X-33 it's as poor as for the space > shuttle, only around 1 at hypersonic velocities. Then it's doubtful > the lifting trajectory could make up for the delta-V shortfall for > this air-launched X-33. > But perhaps we could increase the propellant load. By reducing their > respective temperatures down to near their freezing points, it's known > you can increase the density of the LH2/LOX combination by about 10%. > So let's say the propellant load is now 231,000 lbs. Using still the > 45,800 lbs dry weight, and 453 s vacuum Isp, we get a delta-V of > 453*9.8*ln(1+231,000/45800) = 7,987 m/s. Adding on the 600 m/s we get > from the Mach 2 carrier craft and the 462 m/s we get from the Earth's > rotation at the equator we have a total of 9,049 m/s delta-V. > This is about right when you consider that for either the single SSME > or dual J-2 engine option, the initial launch thrust/weight ratio will > be high at nearly 2 to 1, which will result in lower gravity losses. > However, in any case you would be able to carry only minimal payload. > You might be able to carry 2 crew members with environmental systems. > > However, a problem still is the weight the B-1A would have to carry > compared to its max takeoff weight. See the specifications here: > > B-1 Lancer.http://en.wikipedia.org/wiki/B-1_Lancer#Specifications_.28B-1B..29 > > The max takeoff weight of the B-1B is given as 477,000 lbs. If you > subtract off the 231,000 lbs X-33 propellant load and 45,800 lbs X-33 > dry weight that leaves 200,200 lbs. But the empty weight of the B-1B > is 192,000 lbs, so only 8,000 lbs is left over for the B-1B fuel, and > that does not even include the extra weight that would need to be > added to add strength to the airframe to support the much higher > payload. > One possible way you could reduce the strengthening mass is an idea > used with rockets: the propellant tank being pressurized can help to > support both compressive and bending loads that normally would require > extra strengthening mass. Then by placing the fuel tank for the B-1A > in the fuselage rather than the wings, which is possible because you > no longer need bomb bays, you might be able to solve the problem of > extra strengthening mass. > However, another problem is that the B-1A actually had a lower max > takeoff weight than the B-1B, while also a lower empty weight. You > would need to find a way to give the B-1A the same max takeoff weight > as the B-1B while maintaining its Mach 2+ top speed. > Another solution would not be as palatable to the Air Force. The > Russians currently have in actual operation a Mach 2 bomber that is > larger than the B-1: > > Tupolev Tu-160.http://en.wikipedia.org/wiki/Tupolev_Tu-160 > > It has a max takeoff weight of 606,000 lbs and an empty weight of > 242,000 lbs. That leaves 364,000 lbs left over. That would be well in > excess of what's needed to carry the X-33 and even give it a > significant payload, and for the Tupolev to still have a significant > fuel load. > > The design of the X-33 lifting body airframe was not particularly > advanced once you get by the problem of lightweighting the tanks, > which I have given some methods to solve. The most advanced > characteristic of the vehicles design were the aerospike engines, and > these would not even be needed for this air launched application. Note > also the other competing proposals for the X-33 suborbital > demonstrator by Rockwell and McDonnell-Douglas were about the same in > size and capabilities as the selected Lockheed version, but these > would offer no complications at all in getting the tanks to have the > needed lightweight character since they were of circular cross- > section. > Then it would not be difficult at all for the Russians to make such a > X-33 class spaceplane. And they already have the carrier craft to > serve as its launch platform to orbit. > > Bob Clark The maximum takeoff weight is effected by two factors: the wing area, for the amount of lift they can generate for the heavier weight, and the thrust, for generating sufficient speed for takeoff at the heavier weight. Use of the X-33 as the orbital craft could resolve both of these issues. Most versions of such air launched systems have the orbital craft quite small with respect to the carrier craft. However, an X-33 class spaceplane with an B-1 class carrier craft would have a significant proportion of the carrier crafts wing area. Then why not use this additional wing area to provide additional lift at takeoff? The problem is for biplanes, as this in effect would be, the lift is reduced when the wings are close together. However, the lift can be a large proportion of that due to the total wing area when the gap between the wings is about a chord length: BIPLANE AND TRIPLANE WING LIFT AND EFFICIENCY. http://tpbweb.com/media/catalog/781.pdf By this data the lift can be upwards of 80% of that expected from the separate wing areas, for a gap of wing chord distance. For delta- wings, it would be the mean chord length. But would it be that of the upper wing or lower wing? If the B-1's mean chord is used it might be 40 feet. But if the X-33 means chord is used if might be 30 feet. The X-33 suspended this distance away from the carrier craft would make for a quite ungainly looking vehicle but it would work, at least for takeoff and low speed, where this biplane data is available. A question that would need to be answered is how effective is the biplane lift at supersonic speeds. A disadvantage of biplanes is that they have higher drag compared to a single wing of the same wing area. This is where the high thrust of the X-33 would come in. Using a SSME or 2 J-2 engines would give about 400,000 lbs thrust at sea level. This is multiple times greater thrust than the B-1 and would be sufficient for takeoff of the combined vehicle using aerodynamic lift. So both the B-1's jets and X-33's rocket engines would be used. In fact using both the lift and the thrust of the X-33 gives you more leeway in your carrier craft. You could use the Concorde for example. Note also that use of the rocket thrust from the X-33 would also allow you to reach higher speeds say Mach 3+ before release. This would allow greater payload, since less delta-V would need to be supplied by the X-33 after release. The extra rocket propellant for the X-33 required for firing during the linked portion of the trip would be carried in the carrier craft fuselage. Bob Clark
From: hcobb on 11 Apr 2010 13:28 On Apr 10, 8:29 am, Robert Clark <rgregorycl...(a)yahoo.com> wrote: > Note also that use of the rocket thrust from the X-33 would also allow > you to reach higher speeds say Mach 3+ before release. This would > allow greater payload, since less delta-V would need to be supplied by > the X-33 after release. The extra rocket propellant for the X-33 > required for firing during the linked portion of the trip would be > carried in the carrier craft fuselage. > > Bob Clark Since you need to reach Mach 25+ to orbit this saves you only 12% of the speed requirement while imposing a requirement for an airframe that can at least sustain that ground velocity while climbing. A much better result can be had from a balloon-assisted launch system where the objective is to start the rocket with as much altitude as possible rather than speed. http://academy.grc.nasa.gov/y2008/group-project/proposal-for-a-balloon-assisted-launch-system -HJC
From: Matt on 11 Apr 2010 13:59
On Sun, 11 Apr 2010 10:28:48 -0700 (PDT), hcobb wrote: >On Apr 10, 8:29�am, Robert Clark <rgregorycl...(a)yahoo.com> wrote: >> Note also that use of the rocket thrust from the X-33 would also allow >> you to reach higher speeds say Mach 3+ before release. This would >> allow greater payload, since less delta-V would need to be supplied by >> the X-33 after release. The extra rocket propellant for the X-33 >> required for firing during the linked portion of the trip would be >> carried in the carrier craft fuselage. >> >> � Bob Clark > >Since you need to reach Mach 25+ to orbit this saves you only 12% of >the speed requirement while imposing a requirement for an airframe >that can at least sustain that ground velocity while climbing. > >A much better result can be had from a balloon-assisted launch system >where the objective is to start the rocket with as much altitude as >possible rather than speed. > >http://academy.grc.nasa.gov/y2008/group-project/proposal-for-a-balloon-assisted-launch-system This is a proposal from 2008. Was it approved? |