From: skunk-works-digest-owner@mail.orst.edu To: skunk-works-digest@mail.orst.edu Subject: Skunk Works Digest V5 #627 Reply-To: skunk-works-digest@mail.orst.edu Errors-To: skunk-works-digest-owner@mail.orst.edu Precedence: Skunk Works Digest Thursday, 29 February 1996 Volume 05 : Number 627 In this issue: Yehudi Operational Details Re: YF-22 and YF-23 Re: YF-22/YF-23 Selection (Long [again]) Re: YF-22 and YF-23 Re: YF-22 and YF-23 Re: YF-22/YF-23 Selection (Long [again]) Re: Wired on UAVs Press Release from Hughes Aircraft RE: YF-22 and YF-23 Re: Wired on UAVs Re: Press Release from Hughes Aircraft Re: YF-22 and YF-23 Re: YF-22 and YF-23 Re: YF-22/YF-23 Selection (Long [again]) 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: "I am the NRA." Date: Wed, 28 Feb 96 10:59:31 EST Subject: Yehudi Operational Details (or rather: operational details unknown) I have never seen the Operational; details discussed. The sky is a relatively constant (over the 5 minutes or so involved) brightness, so my GUESS is it was just set by experience, probably based on a few hours testing in various conditions, against ground or water borne friendly observers. (It is interesting to note that one problem with the 'tank' application is that a tank (or a surface vessel) is seen against wider varierty of backgrounds, and so NEEDS better matching.) ========================================= >Maybe this sounds simplistic but ... how would someone in an aircraft know >the location of the observer? Radar, for one. For another, if the a/c was not 'closing' on the target neither a/c nor Uboot cared. If the a/c was going another way, it was not attacking. If so, the a/c did not care if it was spotted, and the Uboot would gamble on some more surface time. >I assume that if one knew the angle from which he was being observed, then he >could match the background as seen from the observer's point of view. How >does one determine that crucial factor? Only a fairly narrow angle of frontal zones of the a/c were of interest. If A/C seen from the side, at range, the Uboot would not attack the a/c. >Worse, wouldn't adjusting one's brightness for one observer tend to make one >more visisble to other observers? In the general case, true. In the specific, yehudi, case, there were no other observers, mostly. (yes. Even using wolf pack tactics....) Yehudi was an evolution to a specific tactical situation: A/C needs to get in close to bomb. U-boot can crash dive before a/c arrives IF it 'sees' the a/c. A/C, while fast, takes time to close the range. >Another thought: In color photography, one adjusts the color of the sky by >use of a polarization filter which is highly sensitive to the angle of the >incident light (the sun). Wouldn't disguise scheme of the sort being >discussed by very suseptible to the use of simple polarised (sun)glasses? Did the Germans have any? US had them, becasue Dr Land invented 'cheap' (easily manufacturable) polarizers. Before that polarizing filters were exotics. I do not know if the WWII Germans had 'simple polarised sunglasses'. And they had to think to try them... regards dwp ------------------------------ From: ahanley@usace.mil Date: Wed, 28 Feb 96 13:33:50  Subject: Re: YF-22 and YF-23 The unusual thing about the streamers or condensation that would come off the YF-23's wing in a tight turn is that it would only come off one wingtip. I believe it was which ever tip was up in a given turn. Art Hanley "My employer has nothing to do with this" (keeps the lawyers happy) ------------------------------ From: ahanley@usace.mil Date: Wed, 28 Feb 96 12:11:08  Subject: Re: YF-22/YF-23 Selection (Long [again]) This is in answer to Tom Gorman's question on the YF-22/YF-23 selection. It was written at home but transmitted here because parts of my PC are still in pieces. Next to the F/A-18E/F vs. F-14D controversy, this was probably the most controversial aircraft selection in a long time. I am not commenting on the selection process from here nor do I mean to imply that the USAF made the "right" or "wrong" choice in choosing the YF-22. I'm just offering an historical explanation on what was reported to have transpired. I've probably gone on too long again... What kind of "tainted" the YF-22's selection was that the ATF competition was not a flyoff in the classical sense. In this particular selection, the decision was not made by operational personnel favoring the characteristics of one plane over the other. The competition was specifically structured so that the two aircraft could not be compared with each other, and in fact their relative performance to each other remains classified. This was one of the aspects of the competition that caused some (possibly undeserved) cynicism at the time. Another was the delay in the program USAF put in towards the end. Northrop was clearly well ahead of Lockheed in getting their bird in the air. This was reportedly due to three factors. One was that it was said the Lockheed team had to perform a heroic effort to perform a major redesign to their submission, which ended up in the excellent aircraft that eventually flew. It has been noted that the early depictions of the Lockheed ATF looked substantially different from the final form, while Northrop's design essentially showed few changes from the early depictions to the final one. Second, there were press reports that General Dynamics was late in delivering its sections of the YF-22. Third, Northrop had made as one of its goals that it would get into the air well ahead of its competition, so that it could rack up more hours. Of course, flying around for months while "the other guys" were still working on getting in the air is not a minor advantage in perception during a competition. When USAF "restructured" the program, putting in a six month delay for "refinement", a number of eyebrows were raised. This delay corresponded to the amount of time Lockheed was behind. Rightly or wrongly, this was perceived in many quarters as penalizing Northrop by delaying the program until Lockheed could catch up. Another action that may have been taken the wrong way was USAF's statement that, unlike the F-16-F/A-18 case, the Navy would not be allowed to buy a variant of the aircraft not selected for its NATF. It was already known by this time that the naval model from either team was going to be so different from the landbased model that little money would actually be saved by getting it from the same team--the major common features by this time were going to be some of the avionics and engines. The naval F-22 would have been a variable sweep design, while I have been told that the naval F-23 would have been a canard equipped delta. It wouldn't hurt to get it from the same team, it just wouldn't help that much because a massive R&D effort and a second production line were still going to be needed. Remember, this was based on the situation at the time of the selection. Now, years later, it would be far more expensive to develop, say, a naval F-23 than a naval F-22. The third thing that possibly unfairly put the F-22 selection "under a cloud" was what little we know about the relative performance of the two aircraft. USAF in the RFP repeatedly stressed speed (especially in supercruise) and stealth. Most reports say that the YF-23 was clearly superior in these areas. In fact, the YF-23's supercruise speed with the GE engine (both aircraft showed better performance with the YF120) was so high that it was classified. It also was reported to accelerate better. Some reports indicated that the F-23 could carry two more missiles internally than the F-22. The YF-23, even though somewhat larger, was lighter. This disparity would have grown in the production versions (assuming both competitors actually met their weight targets). The reason revolves around how close the YF-23 was to the production configuration and how far it was ahead of the YF-22 in getting built. Originally USAF set stringent airfield requirements for the ATF. In order to meet the landing distance requirement (with the thrust the ATF would have, meeting the takeoff requirement was easy) both competitors planned the use of thrust reversers. Convincing itself once again that airfields are invulnerable, USAF dropped the stringent landing distance requirement. As a result, for cost reasons both competitors dropped thrust reversers from their designs. Lockheed was still far enough away from cutting metal (or composite) that they could eliminate all remnants of it from their design. Northrop, though, had already locked their design and were too far along to completely eliminate that part of their design. As a result, while the YF-23 did not have thrust reversers, the engine nacelles were still sized and shaped for them and some of the internal structure for them was still there. On the production version, this extra structure would have been eliminated, further saving weight. The production F-23 reportedly would incorporate only minor changes from the YF-23. The nacelles were to be refined, as previously mentioned. USAF had expressed a realistic reservation about Northrop's use of a single launching arm in their missile bay. The concern was that a single failure here would mean the fighter couldn't launch weapons. The production version would have had two arms, according to reports. Reports also indicate that the wing roots would have been extended forward into chines. This increased stealth a bit more and would have also allowed production versions to carry an additional two AIM-9 types internally. The YF-22 was said to be superior in low speed maneuverability and in at maneuvers at extremely high angles of attack, due in large part to its use of vectored thrust. However, the RFP did not call for dramatic maneuverability enhancements in these areas over the F-16. The F-22 was also thought to be easier to produce and had more control surfaces, it's rear empennage not having to perform double duty as did the F-23's. An interesting thing about the F-23 design's rear empennage-- Although unusual looking, it served to mask the engine exhaust, and more importantly the surrounding metal, from IR sensors. Only from directly behind or from the upper rear quarter could they be "seen". Also, the shape and location of the empennage was particularly ingenious. With most aircraft, operating at high angle of attack results in the wings or fuselage blocking airflow over the vertical stabilizers. Look at a model of the YF-23. There is virtually no flight attitude where the rear empennage will not be in clear air, especially when the flaperons were drooped. The YF-22's vertical control surface may be masked at higher angles, but it uses thrust vectoring to compensate. The two competitors also tended to demonstrate different things in their flight evaluations. Lockheed worked on demonstrating high angle of attack performance and fired an AIM-9 and an AIM-120. Northrop fired no weapons and concentrated on demonstrating rapid turnaround and ease of handling. Wind tunnel tests indicated that like the F-22 the F-23 had no angle of attack limitations. It could do tailslides and the like and was expected to self-recover from any spin except when the weapons doors were open. In past competitions, the capability and performance reasons why one aircraft was selected over another were clearly stated and usually forestalled much controversy. For example, when the F-4H Phantom II was selected over F-8U III, it was acknowledged that the F-8U III was faster, more agile, had longer range and was cheaper. However, the Phantom had more versatility and potential for air-to-ground and was two crew, which was superior in multi-bogey and ECM environments. It also appeared that it would come aboard the carrier better. Those were the reasons it was selected. History has shown that the correct choice was made. Similarly, the superiorities that Grumman's proposal for the F-14 over the other proposals were clearly enumerated. Same thing for McDonnell's F-15 submission over its competitors (trivia note: Some reports indicated that North American's proposal was actually judged to have superior performance, but was too risky). The F-16 versus the F-17 choice was clearly explained, as was the F/A-18 over the navalized F-16. In the ATF case, though, once it was established that the proposals met the USAF's minimum requirements and would do what the bidders claimed, relative performance and capability did not seem to be a major factor in the selection. The evaluation teams were not allowed to fly both aircraft. They were not to compare notes or report on relative performance. The evaluation was not in terms of relative performance but rather in a series of red, yellow, green and blue indicators for each area of the requirement. These indicators were designed so that they could not be added up to produce an overall score. Further the System Program Office was specifically directed not to make a recommendation for either aircraft. The announced reason given for the USAF Secretary's selection was a superior management plan and greater confidence in the team. Macair (Northrop's partner) later stated that they blamed themselves for not insisting on better documentation of their plan from their team. This is different from previous selections and the continued lack of data on the two aircraft's relative performance has led to continued low key cynicism, justified or not. Art "Blabberfinger" Hanley Gosh! He wrote all that and not one word, not one shred, not even an iota of the above represents anything to do with his employers, nor any positions they may have (which they wouldn't reveal anyway). ------------------------------ From: BaDge Date: Wed, 28 Feb 1996 17:15:37 -0500 (EST) Subject: Re: YF-22 and YF-23 So has anyone had an advance look at the X-36, RPV, due for roll-out the second week in March (3/19)? We've seen the PR, so we know it's a 'Wing', no tail, but that's about it. I'm shocked that Testors missed this one, heh. regards, ________ BaDge ------------------------------ From: Jack Gibbons Date: Wed, 28 Feb 1996 14:01:38 -0800 Subject: Re: YF-22 and YF-23 Actually, I've heard the contrail item mentioned in several different articles and programs concerning the 22 / 23 competition.. One show, I think it was Wings, showed the 23 leaving a very distinctive contrail where the 22 did not. Although many times this can just be atmospheric conditions. At 03:34 AM 2/28/96 PST, you wrote: >If you mean the vapor trail (I`m not familiar with a "vector trail") - don`t >be so quick to blame the airframe. Its more likely the weather. >Why was the `22 chosen? >My guess is it was a F17-type decision. Good plane, just not all there yet. > >Chuck > > Lumber >:-[ - "I've done it over and over.. You see, I kill breeders." - "God is dead." -Nietzche Here thar be monsters! - "Nietzche is dead." -God "Hey ho! Let's go!" ******************************************************************* * E-mail: lumber@zoom.com * jackg@holobyte.com * ******************************************************************* - -----BEGIN PGP PUBLIC KEY BLOCK----- Version: 2.6.2 mQCNAzABlKkAAAEEAMMmxB7oaUnMLfPqBFW0dOzJUlQqeejtmKXuGhGG4k2IhoD+ Mg9zrHuzW6s+pvM3kNswfpd7iyA4JnEmZxdDQYNc+ww5TZBoZJPr7h/dqjG5Ju4V B7OhADv35JyP0N68Q0qM3zynSbLTIAC7O6nRSfBHe08GrDIPLAyeSckdMkAZAAUR tB5KYWNrIEdpYmJvbnMgPGx1bWJlckB6b29tLmNvbT4= =hsJL - -----END PGP PUBLIC KEY BLOCK----- ------------------------------ From: Wei-Jen Su Date: Wed, 28 Feb 1996 20:52:19 -0500 (EST) Subject: Re: YF-22/YF-23 Selection (Long [again]) On Wed, 28 Feb 1996 ahanley@usace.mil wrote: > maneuverability enhancements in these areas over the F-16. The F-22 was > also thought to be easier to produce and had more control surfaces, it's So, one of the reason of chosing the F-22 was because of its simplicity, same as the case of the choose of its engine (the YF-119). Well... as the Skunk Works slogan: KISS (Keep It Simple Stupid) May the Force be with you Su Wei-Jen E-mail: wsu02@barney.poly.edu ------------------------------ From: Kathryn & Andreas Gehrs-Pahl Date: Wed, 28 Feb 1996 21:50:07 -0500 (EST) Subject: Re: Wired on UAVs Rafal Rohozinski wrote: >Just as an aside, the latest issue of Wired magazine (UK version) has an >extended peice on UAV's including Predator, Hunter and Darkstar. I am not >sure if the US version of the magazine carries the same peice. Yes, the US version carries the same article, and because they actually called me up to verify some things, I want to review it here. The article does not include many errors, and is not written for the aircraft enthusiast, rather for the internet/computer user (somehow), but it promulgates a strange misconception, which I noted in several places before, in print media, as well as on the internet. This misconception is: UAVs/RPVs appeared suddenly in the late 1980s or early 1990s. This is not true! RPVs (Remotely Piloted Vehicles), Drones, and PTA (Piloted Target Aircraft) existed (and were used by the US military in many roles) since before even the Second World War. They were used as targets as well as for surveillance and reconnaissance, and even armed versions existed. The RAPTOR/TALON project or armed DarkStar or Global Hawk UAVs would be new concepts only in their greater autonomy and their envisioned specific targets: Theater Ballistic Missiles during their Boost-Phase (Take-Off). Also Long-Endurance, High-Altitude or even Stealth characteristics are not really new for UAVs. What is new, is the proposed ability to fly missions "autonomously" (hence the new UAV (Unmanned Aerial Vehicle) nomenclature), and the ability to relay near-real-time data, even though these technologies are not really new either (e.g. Cruise Missiles, dating back to the German V-1, which all employ some sort of preprogrammed, autonomous flight, and "Senior Span" U-2Rs which employ satellite data-links). All in all, the technical and historical accuracy does not even approach Popular Mechanics/Science standards. - -- Andreas [a little picky today] - --- --- Andreas & Kathryn Gehrs-Pahl E-Mail: schnars@ais.org 313 West Court St. #305 or: gpahl@raptor.csc.flint.umich.edu Flint, MI 48502-1239 Tel: (810) 238-8469 WWW URL: http://www.umcc.umich.edu/~schnars/ - --- --- ------------------------------ From: Kathryn & Andreas Gehrs-Pahl Date: Wed, 28 Feb 1996 22:08:47 -0500 (EST) Subject: Press Release from Hughes Aircraft Hughes Aircraft awarded $54.6 million contract for Joint Strike Fighter System. EL SEGUNDO, Calif. -- Feb. 28, 1996 -- Hughes Aircraft Company recently received a $54.6 million contract to develop affordable advanced multifunction active array technology that is the gateway to the next generation of tactical avionics systems. "This contract, awarded by the Joint Advanced Strike Technology (JAST) Program Office, is the first step toward the development of a truly Multi- functional Integrated Radio Frequency System (MIRFS) that could become the standard for Joint Strike Fighter (JSF) family of aircraft," said Louis M. Bogdanovic, president of Hughes Aircraft's Radar & Communications Systems segment. He said the MIRFS program involves building a cost effective system that integrates radar, electronic warfare features, and communications functions into multifunction apertures for the next generation Joint Strike Fighter aircraft that will complement the Navy's F/A-18E/F and replace the Air Force F-16, and the Marine Corps AV-8B and F/A-18 aircraft. Technologies developed during this contract can also be incorporated into upgrades for other aircraft, such as the F/A-18E/F, the F-15, and possibly the F-22. "Now, the really tough challenge begins," Bogdanovic continued. "Once again, the integrated product teams are working and will have to use their creative powers to come up with solutions to problems that have never been solved before. But building on research and development as we have done in processors, active array, low observable radar, and other technologies, I am confident we will succeed." Under terms of the contract, Hughes Aircraft's Radar & Communications Systems segment will undertake a three-stage program to design, build, integrate, and flight test an active array radar by the year 2001. The first task which begins immediately and runs through the fall of 1996, is the concept development phase. Upon its completion, work will begin on the second stage, expected to last about two and a half years, during which Hughes will design and produce a state of the art multi-function RF aperture, develop an extensive suite of air-to-surface software modes, and will demonstrate the system in a laboratory environment. The final task leading to a down select is to demonstrate the system in flight in a platform yet to be determined. "One key to the success of the program will be in our integrated product team relationships with the three teams developing the candidate aircraft for the Joint Strike Fighter program," Bogdanovic said, "and our coordination with the other members of the Hughes Aircraft team including HE Microwave in Tucson, Ariz., our microelectronics division and Hughes Gallium Arsenide operations in Torrance, Calif. "Equally important are the great contributions that our subcontractors, which will include TRW, ITT, the British Defense Research Agency, and the Environmental Research Institute of Michigan (ERIM), bring to the IPT process," Bogdanovic said. Hughes Aircraft is a unit of Hughes Electronics Corp. The earnings of Hughes Electronics are used to calculate earnings per share attributable to GMH (NYSE symbol) common stock. - -- Andreas - --- --- Andreas & Kathryn Gehrs-Pahl E-Mail: schnars@ais.org 313 West Court St. #305 or: gpahl@raptor.csc.flint.umich.edu Flint, MI 48502-1239 Tel: (810) 238-8469 WWW URL: http://www.umcc.umich.edu/~schnars/ - --- --- ------------------------------ From: "Mark E. Schmidt" Date: Thu, 29 Feb 96 07:00:29 UT Subject: RE: YF-22 and YF-23 yes, the upward moving (more lift creating) wing - ---------- From: owner-skunk-works@mail.orst.edu on behalf of ahanley@usace.mil Sent: Wednesday, February 28, 1996 5:42 PM To: skunk-works@mail.orst.edu Subject: Re: YF-22 and YF-23 The unusual thing about the streamers or condensation that would come off the YF-23's wing in a tight turn is that it would only come off one wingtip. I believe it was which ever tip was up in a given turn. Art Hanley "My employer has nothing to do with this" (keeps the lawyers happy) ------------------------------ From: dadams@netcom.com (Dean Adams) Date: Thu, 29 Feb 1996 01:33:09 -0800 (PST) Subject: Re: Wired on UAVs > The article does not include many errors, and is not written for the aircraft > enthusiast, rather for the internet/computer user (somehow), but it > promulgates a strange misconception, which I noted in several places before, > in print media, as well as on the internet. > > This misconception is: UAVs/RPVs appeared suddenly in the late 1980s or early > 1990s. > > This is not true! That's for sure! One of the more glaringly obvious examples is the extensive use of drones/RPVs in Vietnam. And of course everyone's favorite high-speed, stealthy UAV is none other than the Lockheed D-21, a product of over 30 years ago. ------------------------------ From: fmarkus@pipeline.com (Frank Markus) Date: Thu, 29 Feb 1996 11:09:49 -0500 Subject: Re: Press Release from Hughes Aircraft On Feb 28, 1996 22:08:47, 'Kathryn & Andreas Gehrs-Pahl ' wrote: >Hughes Aircraft awarded $54.6 million contract for Joint Strike Fighter >System. [Much omitted] But building on research and development as we have done in >processors, active array, low observable radar, and other technologies, I am >confident we will succeed." [Much more omitted] Question: What is low observable radar? It sounds like an oxymoron. All that I can think of is some sort of spread spectrum or low power emitter -- and both seem quite detectable. What is this technology? ------------------------------ From: erebenti@MIT.EDU (Eric Rebentisch) Date: Thu, 29 Feb 96 10:41:26 Subject: Re: YF-22 and YF-23 > Considering all of this, it seems to me that the 23 is a superior plane, > what with its manueverability, stealth, and armament. This leads me to > ask, why was th YF-22 chosen? Is there something I missed? Any answers? > One thing that is missing in all the speculation I've seen on the YF-22/YF-23 decision is reference to actual data. One of the benefits of having a prototype competition is that the Air Force could actually test the various characteristics of each aircraft and collect *real* data on which to base their source selection decision. I've seen the public releases of pictures of the two aircraft in flight (pretty cool!), and some very limited point-condition flight performance characteristics, but nothing that would qualify one to say that one aircraft was categorically better than the other. On the other hand, people in the SPO (system program office) and the source selection committee did have access to all the test data, such as flight performance, reliability, maintainability, acquisition cost, O&M costs, design maturity, and things like that. Given that this program was one of (if not THE) top priority programs for the Air Force at the time, perhaps we can assume that hand-picked, rational, highly motivated people with complete access to a full set of data were able to make the best tradeoff of all the relevant factors and select the best airplane. BTW, I've spoken with a few people in the F-22 SPO (including the program manager and chief engineer), and they're all professional, competent people who are trying to make the best aircraft they can for the money they have available. I doubt they were playing games when it came time to pick the winner. Now, if you still subscribe to the political conspiracy theory (which seems to hang around a striking number of competitions that Northrop lost), then consider this. Assume that the two aircraft were close enough in performance that the Air Force would willingly allow the decision to be made on "political" grounds (if there were significant differences in aircraft performance, then we could assume that USAF would have chosen the superior aircraft, given the program's importance). Now, on what political basis do you make that decision? Congressional districts? If that is the basis, then the program is probably already headed for disaster because it doesn't have enough intrinsic merit going for it on the basis of threat and capabilities to justify its cost. More likely, the "political" decision would probably only rise to the level of SAF, or OSD at most, so the likely basis for the "political" decision would be the preservation of the defense industrial base. That's shaky, given that the industrial base was in pretty good (-looking, at least) shape back in 1990, but let's go with that anyway. If the two planes were equivalent, and industrial base diversity was preserved by going with the YF-22, then it was still a good decision, because having 2 dominant fighter design houses is still better than having just one. This is a critical issue because we now have essentially 2 fighter shops and 1 upcoming program (JSF) for the next 20 years or so. Who's going to get that award? What will the "loser" do? Despite the logic of a political decision on the ATF selection, I have yet to see any basis to claim that Northrop got screwed yet another time because of politics. Maybe the armchair generals should have a little more faith in the engineers and program managers who actually made the decision (and had the information available on which to make that decision). Maybe the YF-22 really was the better airplane. Eric ------------------------------ From: Wei-Jen Su Date: Thu, 29 Feb 1996 16:11:29 -0500 (EST) Subject: Re: YF-22 and YF-23 On Thu, 29 Feb 1996, Eric Rebentisch wrote: > Now, on what political basis do you make that decision? Congressional > districts? If that is the basis, then the program is probably already > headed for disaster because it doesn't have enough intrinsic merit going > for it on the basis of threat and capabilities to justify its cost. More > likely, the "political" decision would probably only rise to the level of > SAF, or OSD at most, so the likely basis for the "political" decision > would be the preservation of the defense industrial base. That's shaky, Sometimes when we are talking about "political" problem, we are talking about the mafia from the industry trying to get their airplane accepted from the goverment... May the Force be with you Su Wei-Jen E-mail: wsu02@barney.poly.edu ------------------------------ From: Date: Thu, 29 Feb 96 14:28:10 PST Subject: Re: YF-22/YF-23 Selection (Long [again]) Comments by : Art Hanley@IM@SPK Date : Thursday, February 29, 1996 14:28:13 Forwarded to : internet[skunk-works@mail.orst.edu] ======================================================================= Reply by : Art Hanley@IM@SPK Date : Thursday, February 29, 1996 14:26:58 Reply to : smtp@SPKSYS12@Servers[wsu02@barney.poly.edu] Reply: Actually, it appears that the YF-23 was the simpler of the two airframe designs. That's one of the reasons it weighed less. There was some thought that it might be somewhat harder to produce, though, because of the larger single composite structures. Regarding the YF120, it's big "complication" was a valve which changed internal airflow to optimize it for the regime it was operating in at the time. Should the valve fail, the engine would still be operational, it would just lose efficiency and may not be able to generate full power at all points in the envelope. On the other hand, it was apparently a somewhat more powerful engine. Art Hanley These views are only my own and do not represent my employer's (Whew! Stayed out of jail again!) -------------------------- [Original Message] ------------------------- To : Cc : From : Wei-Jen Su Subject : Re: YF-22/YF-23 Selection (Long [again]) Date : Wednesday, February 28, 1996 at 12:52:19 pm PST - ------------------------------------------------------------------------------ On Wed, 28 Feb 1996 ahanley@usace.mil wrote: > maneuverability enhancements in these areas over the F-16. The F-22 was > also thought to be easier to produce and had more control surfaces, it's So, one of the reason of chosing the F-22 was because of its simplicity, same as the case of the choose of its engine (the YF-119). Well... as the Skunk Works slogan: KISS (Keep It Simple Stupid) May the Force be with you Su Wei-Jen E-mail: wsu02@barney.poly.edu ------------------------------ End of Skunk Works Digest V5 #627 ********************************* 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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