From: skunk-works-digest-owner@mail.orst.edu To: skunk-works-digest@mail.orst.edu Subject: Skunk Works Digest V5 #131 Reply-To: skunk-works-digest@mail.orst.edu Errors-To: skunk-works-digest-owner@mail.orst.edu Precedence: bulk Skunk Works Digest Tuesday, 12 July 1994 Volume 05 : Number 131 In this issue: Blackhorse [1] - Headers etc. Blackhorse [3] - Addendum Re: SR71 Reactivation Re: SR71 Reactivation mirror world Re: SR-71 reactivation SR71 Reposts missing SR-71 articles Re: SR71 Reposts Re: A-12 vs SR-71 dimensions Blackhorse [2] - Text (part 1 of 4) Blackhorse [2] - Text (Part 2 od 4) Blackhorse [2] - Text (Part 3 of 4) Blackhorse [2] - Text (Part 4 of 4) See the end of the digest for information on subscribing to the skunk-works or skunk-works-digest mailing lists and on how to retrieve back issues. ---------------------------------------------------------------------- From: Frank Markus Date: Tue, 12 Jul 1994 05:45:03 -0400 Subject: Blackhorse [1] - Headers etc. REPOST OF MESSAGES RE: BLACK HORSE FROM SCI.SPACE.TECH TO SKUNK_WORKS REPOSTER'S NOTES: While the following messages do not purport to describe current "black" aircraft, it seems to me that there may be a bit more here than meets the eye. I was particuularly taken by the reference to the cockpit of a U-2 and to the KC-135Q which is, I believe, uniquely tasked to the support of the SR-71. Similarities to aspects of the erstwhile "Aurora" are also of interest as are the missions suggested for the "Black Horse" which seem appropriate to an SR- 71 follow-on aircraft. The messages below suffered considerably during posting and reposting on the Usenet. I have reformatted the text to increase clarity but (with the exceptions of capitalized headers separating the several messages) have left the text intact. --Frank Markus-- Because my mailer would not send the entire file as a single unit, I have been forced to chop it up somewhat arbitrarily into three messages consisting of the headers, the report and an addendum. ========== HEADER BY MODERATOR OF SCI.SPACE.TECH ===================== From: clappm@smtpgw1.plk.af.mil Subject: Black Horse and Usenet Date: Thu, 30 Jun 94 09:38:42 MST Organization: CRL Dialup Internet Access [Mod Note: Mitch mailed this to me and we've discussed how to get his messages posted, which probably will be in the same manner. I am looking forwards to more contributions from him and other active professionals in the field -gwh] Hi. It looks like my original posting got onto the bulletin board okay, but unfortunately I had to hand-type it via Bix. Spending any time or uploading any significant data to sci.space.tech would get prohibitively expensive in short order. I'm working here to try to figure out how to get a newsreader program that will work alongside the ftp and telnet I already have on my PC here at Phillips Lab. SO far, no luck. If you have any suggestions I'd be eager to hear them. I gather from the tone of the postings in the thread I read that Black Horse has been discussed previously. Is any of that stuff archived? How can I get it? Last Wednesday Black Horse was briefed to the Chief of Staff of the Air Force. It looks very good for getting a program going. We are trying to target Oct 1997 for first flight. Mitchell Burnside Clapp clappm@plk.af.mil ------------------------------ From: Frank Markus Date: Tue, 12 Jul 1994 05:47:00 -0400 Subject: Blackhorse [3] - Addendum ========== ADDENDUM: CALCULATIONS & CONVERSIONS =========================== From: Bruce_Dunn@mindlink.bc.ca (Bruce Dunn) Subject: Re: Black Horse Date: Sat, 02 Jul 94 17:26:32 -0700 (PDT) Organization: MIND LINK! - British Columbia, Canada Mitchell Burnside Clapp through George Herbert was kind enough to post a short description of the Black Horse vehicle. Here are a few relevant calculations and conversions from American to International units. > Single stage to orbit flight is technically challenging because the *v > necessary to achieve orbit (30,500 ft/s, typically) Equivalent to 9296 m/sec; many people use 9300 m/sec as representing the delta V needed for low earth orbit (good enough for first order calculations). > The probe and drogue system requires the pilot of the receiver aircraft > to do all the work, and transfers about 250 gallons per minute. The boom > system requires some cooperation between the boom operator and the > receiver aircraft pilot, and can transfer 1200 gallons per minute. [and > later in the article] ... the capability of transferring up to 155,000 > pounds of hydrogen peroxide from the tanker to the receiver. Total peroxide to be transferred is 70,454 kg. A probe and drogue system transfers 945 liters = 1352 kg peroxide per minute, giving transfer times of up to 52 minutes. The boom system transfers 4542 liters = 6495 kg per minute for a transfer time of about 11 minutes. > Table 1 Hydrogen peroxide/jet fuel engine performance > > Ideal Isp (shifting equilibrium), 354, 340, sec > > Losses due to:, , , > geometry, 2.4, 2.4, sec > finite rate chemistry, 1.8, 1.0, sec > viscous drag, 7.8, 6.6, sec > energy release efficiency, 6.7, 7.3, sec > > > Delivered Isp (in vacuum), 335.3, 323.1, sec Its nice to see calculations of delivered Isp. The calculations give real Isp at about 95 % of theortical - this makes me happy, as I have been assuming 95% for the purposes of estimating delivered Isp for pressure fed peroxide/hydrocarbon engines for expendable pressure fed vehicles. There is no term for peroxide used for turbopump gas generators, so the engines presumably must be a closed cycle system (this is also implied by the very high chamber pressure). No such engines currently exist but there is a good potential for a rather straight forward cycle somewhat resembling staged combusion, in which the peroxide: 1) cools the nozzle and chamber 2) is decomposed via a catalyst into superheated steam and oxygen 3) powers the turbopump 4) is injected into the engine, where fuel is added The pumps don't have to handle cryogens (no cooldown needed), and the propellants are dense which lessens the power needed. Nevertheless, I expect that engine development will be the pacing item in Black Horse development (as was true for some of the X-planes). - -- Bruce Dunn Vancouver, Canada Bruce_Dunn@mindlink.bc.ca ------------------------------ From: mangan@Kodak.COM (Paul Mangan) Date: Tue, 12 Jul 94 08:32:02 EDT Subject: Re: SR71 Reactivation SR71.......Idoubt if they are really going to reactivate it. I believe that this is a cover so they can fly the Aurora and get results but still say it is the SR71 if anyone happens to notice it or if they have to say it where they get the pics from. Paul Mangan > From skunk-works-owner@gaia.ucs.orst.edu Wed Jul 6 14:19:24 1994 > Subject: SR71 Reactivation > To: skunk-works@gaia.ucs.orst.edu > X-Mailer: ELM [version 2.3 PL11] > Sender: skunk-works-owner@gaia.ucs.orst.edu > Content-Length: 649 > X-Lines: 10 > > >From what I gather I am much less knowledgable about these things than most > of the contributors on this list but I would like to say that enjoy skunk-works > for the informative and courteous manner which is observed here. Compared with > most other net groups the information/ego ratio is very high! > > Now my question. Is it possible that the SR71 is being considered for > reactivation because Aurora or whatever has been grounded? The probability for > technical difficulties in a mach 4-6 craft would seem high. It could be that a > major problem has Aurora grounded (if it exists) or that overall "down-time" is > unacceptable. Any thoughts on this? > ------------------------------ From: megazone@world.std.com (MegaZone) Date: Tue, 12 Jul 1994 09:48:56 -0400 (EDT) Subject: Re: SR71 Reactivation Once upon a time Paul Mangan shaped the electrons to say... >results but still say it is the SR71 if anyone happens to notice it >or if they have to say it where they get the pics from. That wouldn't work. The SR-71 is too visible, it would be known if they fly them or not. - -- megazone@wpi.wpi.edu megazone@world.std.com megazone@hotblack.gweep.net "I have one prejudice, and that is against stupidity. Use your mind, think!" Moderator: WPI anime FTP site, 130.215.24.1 /anime, the anime FanFic archive; rec.arts.anime.stories, questions to anime-dojinshi-request@wpi.wpi.edu GTW/HU d-- -p+ c++(++++) l u+ e+ m+(*)@ s++/+ !n h- f+ !g w+ t+@ r+@ y+(*) ------------------------------ From: I am the NRA Date: Tue, 12 Jul 94 11:41:34 EDT Subject: mirror world >>results but still say it is the SR71 if anyone happens to notice it >>or if they have to say it where they get the pics from. >That wouldn't work. The SR-71 is too visible, it would be known if they fly >them or not. So they fly the SR71. And they get pictures. Doesn't mean the pictures come from the '71. Or that they don't. The opposition is left guessing. More important _future_ oppositions are left guessing. Its an old magicians trick: Grand gestures with one hand, while the other.... Not that i am saying thats what is/will happen. And if it did it would be expensive... regards dwp ------------------------------ From: Geoff.Miller@Corp.Sun.COM (Geoff Miller) Date: Tue, 12 Jul 1994 09:05:56 +0800 Subject: Re: SR-71 reactivation megazone@world.std.com writes: > The Blackbird first flew for the CIA as the A-12, which was a slightly > smaller single seat recon platrom. (The back cockpit was there, but > was used for equipment.) If the back cockpit was there, then in what dimension was the A-12 smaller than the SR-71? - --Geoff ------------------------------ From: Mark Rogers Date: Tue, 12 Jul 94 10:27:18 PAC Subject: SR71 Reposts Hey ! I seemed to have missed parts 3, 6, and 7 of that interesting article. Did anyone get them, that can forward them to me ?? Thanks +---------------------------------------+++---------------------------+ º MARK S. ROGERS RRT,RCP,BSRT º - BITNET - º º º RSPMRO@LLUVM º º LOMA LINDA UNIVERSITY MEDICAL CENTER º º º DEPARTMENT OF RESPIRATORY CARE º ;-) º º LOMA LINDA, CALIFORNIA 92350 º º +---------------------------------------+++---------------------------+ ------------------------------ From: ron@habu.stortek.com (Ron Schweikert) Date: Tue, 12 Jul 94 11:56:32 MDT Subject: missing SR-71 articles Mary, thanks for posting the articles, looked like some of them didn't make it out of the hanger! :-) >Hey ! > >I seemed to have missed parts 3, 6, and 7 of that interesting article. > >Did anyone get them, that can forward them to me ?? > > >Thanks > >+---------------------------------------+++---------------------------+ >: MARK S. ROGERS RRT,RCP,BSRT : - BITNET - : >: : RSPMRO@LLUVM : >: LOMA LINDA UNIVERSITY MEDICAL CENTER : : >: DEPARTMENT OF RESPIRATORY CARE : ;-) : >: LOMA LINDA, CALIFORNIA 92350 : : >+---------------------------------------+++---------------------------+ Ditto. Thanks! Ron ------------------------------ From: Steve Birmingham Date: Tue, 12 Jul 1994 11:39:40 -0700 (PDT) Subject: Re: SR71 Reposts Interesting. I am missing the same parts. I thought it might have been=20 on my end, but apparently, it may not have been. =20 Could someone please re-post the missing parts? =20 Thanks in advance! Steve Birmingham smb@odo.cypress.ca.us On Tue, 12 Jul 1994, Mark Rogers wrote: > Hey ! >=20 > I seemed to have missed parts 3, 6, and 7 of that interesting article. >=20 > Did anyone get them, that can forward them to me ?? >=20 >=20 > Thanks >=20 > +---------------------------------------+++---------------------------+ > =BA MARK S. ROGERS RRT,RCP,BSRT =BA - BITNET - = =BA > =BA =BA RSPMRO@LLUVM = =BA > =BA LOMA LINDA UNIVERSITY MEDICAL CENTER =BA = =BA > =BA DEPARTMENT OF RESPIRATORY CARE =BA ;-) = =BA > =BA LOMA LINDA, CALIFORNIA 92350 =BA = =BA > +---------------------------------------+++---------------------------+ >=20 ------------------------------ From: larry@ichips.intel.com Date: Tue, 12 Jul 1994 12:08:29 -0700 Subject: Re: A-12 vs SR-71 dimensions megazone writes: >> The Blackbird first flew for the CIA as the A-12, which was a slightly >> smaller single seat recon platrom. (The back cockpit was there, but >> was used for equipment.) Geoff.Miller responds: >If the back cockpit was there, then in what dimension was the A-12 >smaller than the SR-71? The A-12 is shorter in nose and boattail length. If you look at a good picture of both, you can see what I mean. The A-12 also carried less reconnaissance gear that the SR, and had less range (oh so says popular theory). However, because of this, the A-12 was lighter and could achieve greater altitudes and somewhat higher speeds. Larry ------------------------------ From: Frank Markus Date: Tue, 12 Jul 1994 16:23:55 -0400 Subject: Blackhorse [2] - Text (part 1 of 4) ========== REPORT ON BLACK HORSE POSTED ON SCI.SPACE.TECH ========== Here's a copy of the short paper Aerial Propellant Transfer to Augment the Performance of Spaceplanes Captain Mitchell Burnside Clapp Phillips Laboratory, Kirtland AFB, NM 87117 William Nurick, Frank Kirby, Ed Nielsen, Robert O'Leary, and Ray Walsh W. J. Schafer Associates, Inc., Calabasas, CA 91302 and Daniel P. Raymer Conceptual Research Corp., Sylmar, CA 91392 Abstract In-flight propellant transfer to a rocket-powered aircraft permits it to achieve orbit with relatively little propellant compared to taking off fully loaded from a runway. The weight of many key components, such as wings and landing gear, is substantially reduced. The vehicle takes off like a conventional aircraft under rocket power from two of its seven engines, using jetfuel (JP-5) and a non-cryogenic oxidizer (H2O2) After rendezvous with and propellant transfer from a tanker aircraft, the vehicle lights all its engines, accelerates to high speed, and pulls up into a steady climb intoorbit. Non-cryogenic, non-toxic propellants permit the propellant transfer to use existing tankers, and a small aircraft similar in size toan F-16 could demonstrate the capability and achieve orbit. Many important military missions could be performed by such an aircraft. The concept is sufficiently simple that relatively little in the way of new facilities or support equipment is required. Introduction The mass of a single stage rocket vehicle at the beginning of its mission Mo is related to the mass at the end of the mission Me by the rocket equation: Mo/Me = exp(Dv/Isp g) where the symbol Dv represents the required mission velocity change, including losses due to aerodynamic drag, gravity, back pressure on the engines, steering, and so forth. Isp is the specific impulse of th e engine in a vacuum, (defined as the number of pounds of thrust per pound per second of mass flow through the engine), and g is the acceleration ofgravity at Earth's surface, which appears in the equation to convert mass to force so that the argument of the exponential is dimensionless. Single stage to orbit flight is technically challenging because the *v necessary to achieve orbit (30,500 ft/s, typically) imposes mass ratios that are difficult to achieve with current structural technology. The usual approach is to seek more energetic propellants with high Isp values. Airbreathing approaches are also an attempt to achieve large Isp. This tends to involve propellants that are not very dense and difficult to handle,such as liquid hydrogen, or impose surpassingly difficult design and operations problems such as those that have afflicted the National Aerospace Plane program. Single stage rocket vehicles fall into three principal configuration categories: vertical takeoff/horizontal landing, such asthe SSTO/R vehicle proposed by the NASA Access to Space Study, vertical takeoff/vertical landing, such as the McDonnell Douglas Delta Clipperdesign, and horizontal takeoff/horizontal landing, such as the Boeing RASV or British HOTOL designs. Between the first two of these, there is no obviousdistinction in terms of empty weight. Credible design studies appear to givesimilar weight estimates for similar vehicles. Horizontal takeoff and landing vehicles, however, tend to be much heavier for a given payload because of the unique requirements imposed by runway takeoff. Wing loads at rotation and the weight of landing gear are of particular concern. Generally horizontal takeoff and landing vehicle designs tend not to be pure single stage to orbit, but rely instead on sled launch or auxiliary boosters to reduce gross weight. ------------------------------ From: Frank Markus Date: Tue, 12 Jul 1994 16:24:50 -0400 Subject: Blackhorse [2] - Text (Part 2 od 4) The purpose of this paper is to discuss another approach for operating spaceplanes off conventional runways with conventional facilities: using in-flight propellant transfer to reduce the takeoff gross weight of a rocketpowered aircraft, and hence its size, weight, and cost. This is not an attempt to solve the rocket equation problem by means of increasing Isp, but by decreasing Dv. Beginning the mission to space from tanker altitude and airspeed reduces the amount of propellant that must be expended overcoming drag and gravity losses. The emphasis is on maximizing theuse of existing components and keeping the design as simple as possible. Hence, we will use existing tankers, landing gear, and conventional technology as much as possible and examine the resulting size of the vehicle. A contracted six-week study between Phillips Laboratory, WJ Schafer Associates, and Conceptual Research Corporation developed this concept further. The ground rules for the study were: Horizontal takeoff like an aircraft Two engines firing at takeoff Propellant transfer at 40,000-43,000 ft Hydrogen peroxide and jet fuel propellants Power-off landing LEO mission Throttling during propellant transfer Maximize use of existing facilities and support equipment Conservative design assumptions Tanker aircraft selection In-flight refueling is commonplace in the US Air Force and Navy today. Two systems are used: the Navy's probe and drogue system and the Air Force's boom refueling system. The probe and drogue system requires the pilot of the receiver aircraft to do all the work, and transfers about 250 gallons per minute. The boom system requires some cooperation between the boom operator and the receiver aircraft pilot, and can transfer 1200 gallons per minute. The boom refueling system was selected for this design because of its high rate of propellant transfer. Two types of tankers use the boom system today: the KC-10 and KC-135. Of these, the KC-135 is smaller, less expensive, and more readily available. Of particular interest is the KC-135Q and KC-135T. These aircraft have an isolated fuel system, from which the tanker's own engines cannot draw. This will allow dedicated rocket propellant tankers to operate with only minor impact on the tanker's own systems. To avoid a costly development program, and the need to completely re-engineer the transfer system, the propellant carried by the tanker should be non-cryogenic and non-toxic. Propellant Selection There are only a few non-cryogenic oxidizers available: red fuming nitric acid, nitrogen tetroxide, and hydrogen peroxide are the obvious choices. Of these, only hydrogen peroxide is non-toxic. It has other advantages as well. It is very dense (1.432 g/cc in 98% concentration). It has a vapor pressure about one-ninth that of water. It is relatively inexpensive because it is an ordinary industrial chemical rather than a dedicated rocket propellant. Because it is a good coolant, ordinary JP-5 rather than expensive RP-1 can be used as the fuel. Although some special precautions must be taken to prevent it from decomposing in the presence of impurities, it is a stable molecule, and once those precautions have been taken it essentially handles like water. Detailed analysis of a hydrogen peroxide/jet fuel engine indicates the following performance figures at a mass mixture ratio of 7.30:1 (oxidizer:fuel). The two columns in Table 1 are for the two versions of the engine. The first version is operable at sea level and permits the aircraft to take off, rendezvous with the tanker, and transfer propellant. The second version is only operable at tanker altitude or above,and is optimized for the climb to space. Table 1 Hydrogen peroxide/jet fuel engine performance, , , Climb Engine, Takeoff Engine, Chamber pressure, 3000, 3000, psia Exit plane pressure, 1.0, 5.7, psia Expansion ratio, 240, 70, -- Ideal Isp (shifting equilibrium), 354, 340, sec Losses due to:, , , geometry, 2.4, 2.4, sec finite rate chemistry, 1.8, 1.0, sec viscous drag, 7.8, 6.6, sec energy release efficiency, 6.7, 7.3, sec Delivered Isp (in vacuum), 335.3, 323.1, sec Thrust, 19930, 19210, lb Weight, 280, 310, lb ------------------------------ From: Frank Markus Date: Tue, 12 Jul 1994 16:26:52 -0400 Subject: Blackhorse [2] - Text (Part 3 of 4) The advantages of the aerial propellant transfer concept are threefold. First, the propellants are at a very high density -- 1.32 g/cc of propellant at the mixture ratio given. This leads to a smaller vehicle and the capability of transferring up to 155,000 pounds of hydrogen peroxide from the tanker to the receiver. Second, they are non-cryogenic, so that the modifications to the KC-135Q or KC-135T model tanker will be minimal. Finally, the mixture ratio is unusually high. At a mixture ratio of 7.30 to 1, 88 per cent of the benefit of aerial propellant transfer is available if one propellant only is transferred. This helps with keeping the operation simple and removes some safety concerns with simultaneous propellant transfer. Mission Profile The mission profile begins with a takeoff from a conventional runway using the two takeoff rocket engines for thrust. The aircraft is 1loaded with all the fuel it needs for the climb from the tanker to orbit. It also has fuel and oxidizer aboard sufficient for 15 minutes of atmospheric flight. The total weight of the vehicle at takeoff is about 50,000 pounds, but by the time it achieves tanker rendezvous at 43,000 feet and 0.85 Mach number its weight has dropped to about 38,000 pounds. When the aircraft meets the tanker it takes on about 147,000 pounds of hydrogen peroxide. It then disconnects from the tanker and climbs to space. As it inserts into orbit, its weight has dropped to about 16,500 pounds. After performing its orbital mission, the aircraft reenters and glides to a normal landing at a runway. Weights The weight buildup of the vehicle will determine whether it is possible to enclose the required volume of propellant in an aircraft that weighs little enough to permit that propellant to launch it into space. The table below indicates the assumptions for each of the major weight components and the total weight of the system. The basic assumptions made for the vehicle are to apply conventional structural technology by forming the blended wing/body of the aircraft from ordinary aluminum alloy. The thermal protection system technology deemed suitable for this application is carbon/silica carbide for the nose cap, DuraTABI for acreage areas on the lower surface, and a lightweight blanket insulation for the upper surface. The crew cabin accommodations are austere, as in the U-2 reconnaissance aircraft. Table 2 Weight Breakdown (pounds), Structures Group, 6,686 Wing, 1,572 Vertical tail, 739 Fuselage, 2,924 Main landing gear, 916 Nose landing gear, 243 Engine mounts, 292 Propulsion Group, 3,091 Engines, 2,120 Fuel system, 971 Equipment Group, 1,181 Flight controls, 372 Instruments, 142 Avionics, 567 Furnishings, 100 Mission-specific Group, 4,000 Reaction controls, 400 Life support, 800 Thermal protection system, 2,800 Total Empty Weight, 14,958 Load Group, 33,494 Payload, 1,000 Crew, 440 Propellant, 32,054 Takeoff gross weight, 48,452 Tanker rendezvous weight, 37,380 Oxidizer transfer, 146,870 Gross light-off weight, 184,250 ------------------------------ From: Frank Markus Date: Tue, 12 Jul 1994 16:27:52 -0400 Subject: Blackhorse [2] - Text (Part 4 of 4) Design Considerations Unlike most spaceplane designs, this vehicle needs to have a particularly high subsonic lift to drag ratio. This is necessary for two reasons. First, the requirement to fly in the atmosphere on the rocket engine impels the designer to minimize thrust required, so that the rocket propellant load at takeoff remains small. Second, the vehicle's gross weight changes by a factor of about 4.5 during propellant transfer. The maneuver will be very difficult for the pilot to fly if the aircraft does not have a good cruise lift-to-drag ratio. The aircraft features a highly blended design to maximize volume. The double-delta planform is adopted to provide minimal change of the aerodynamic center over a broad speed range, and also to provide a large strake to hold fuel and oxidizer so that the center of gravity does not move as the propellant is consumed. The overall wing area is 780 square feet. The wing loading is sufficiently low that no lift devices such as flaps or slats should be needed for takeoff or landing, especially with the enormous thrust available from the rocket engine. Low wing loading may also moderate the thermal environment during reentry. Flight test Unlike most space vehicles, it will be possible to test the aircraft proposed here in a conventional flight test environment. No special range requirements beyond what is conventionally available at, for example, Edwards AFB should be required. Because there are aviators aboard the vehicle, no requirement for a destruct package exists. Aside from storage areas for the new propellant, it should not prove necessary to construct any new facilities for any phase of this program. The flight test program could begin in a conventional build-up fashion, starting with taxi and ground tests, first flight, performance, and flying qualities testing. This phase of the program would emphasize handling qualities while connected to the tanker boom, because the oxidizer transfer will quadruple the weight of the aircraft when it takes place. Once the flight control system has been qualified, transfer of steadily increasing amounts of oxidizer would support envelope expansion and flight to increased altitudes and airspeeds. Exoatmospheric flight and reentry could be investigated, and the operational envelope of the thermal protection system could be determined.The capability of the system to perform ballistic transfers to anywhere on earth within one hour could be demonstrated. Loading the aircraft with fuel and oxidizer at 7.30:1, up to the maximum takeoff weight, could also permit exoatmospheric flight without propellant transfer. The ballistic ferry range of the aircraft under these conditions is about 3200 nautical miles, allowing for some aerodynamic range extension at the end of the trajectory. An orbital flight attempt would follow the envelope expansion phase. Investigation of on-orbit flying qualities could proceed at this point, as well as an experimental determination of reentry cross range. One sub-phase of the orbital flight test program of particular interest would be on-orbit propellant transfer. If the aircraft were completely refueled in low earth orbit, it would have enough Dv to visit anywhere in cislunar space, such as geostationary orbits, or to perform multiple plane changes and visit many different points on a single mission. Reentry from increased altitudes and entry speeds could be tested, yielding an assessment of the capability of a high temperature reentry capability in realistic conditions. Conclusions Using in flight propellant transfer to reduce the Dv needed to fly to space makes it possible for a fighter-sized aircraft to achieve orbit. The enabling technology to do this is non-cryogenic, non-toxic rocket propulsion based on H2O2 and JP-5. Developing this capability permits a variety of militarily significant capabilities to be demonstrated. ------------------------------ End of Skunk Works Digest V5 #131 ********************************* To subscribe to skunk-works-digest, send the command: subscribe skunk-works-digest in the body of a message to "majordomo@mail.orst.edu". If you want to subscribe something other than the account the mail is coming from, such as a local redistribution list, then append that address to the "subscribe" command; for example, to subscribe "local-skunk-works": subscribe skunk-works-digest local-skunk-works@your.domain.net To unsubscribe, send mail to the same address, with the command: unsubscribe skunk-works-digest in the body. 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