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#31
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Yama wrote:
"Scott Ferrin" wrote in message ... He also seems to have left out the ESM system which is quite elaborate in the F-22. It can take an AMRAAM shot with it without even using it's main radar. Also he was incorrect on the F-22's speed. The mach 1.7 he lists in in dry thrust and it wasn't even max military power. Paul Metz stated on a Discovery special that the maximum speed of the F-22 is classified but that it will go Mach 2.5. To quote him ". . .it's fast, I mean it's REALLY fast. It's top speed is classifed but it will do Mach 2.5" This suggests that the top speed in afterburner is over Mach 2.5. Paul Metz is the chief test pilot of the F-22 program. I am sceptical. Doesn't F-22 have fixed intakes? Speeds over mach 2.0 are pretty much impossible to attain with fixed intakes. Besides, such speeds require some special materials in radome, canopy etc. which tend to be more expensive, may not be compatible with stealth requirements etc. The radomes of many mach 2+ aircraft are exactly the same sort of construction (materials, etc.) as that on aircraft from the 1950s. The fiberglass form is essentially transparent to RF - but nothing which a special coating (to replace the normal rubber) can't make stealthy and concealing. Besides - the F-22 is reputed to be using a large number of small active arrays (part of the skin) - in place of a conventional mechanical or electronically-steered antenna. It's liable to be a mess of cabling (or waveguide and ferrites) beneath the skin - but an amazing advance. |
#32
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On Sun, 30 Nov 2003 11:01:04 -0700, "Tex Houston"
wrote: "Scott Ferrin" wrote in message .. . Despite what much of the media would have you believe fixed inlets mean zippo. The XF8-U Crusader III's inlet was fixed and it was good up to Mach three. The highest it got was 2.3 because of the plasic windshield and they planned to replace it with a glass one shortly there after but the program ended up getting cancelled. The test pilots were confident it would have reached 2.9 as it was still rapidly accelerating at 2.3. It all depends on what speed the inlets are optimized for. IIRC the Bomarc had fixed inlets too and the B model was good for well over Mach 3. Come to think of it I'm pretty sure ASALM had a fixed inlet too and it went well over Mach 5. March AFB used to have an LGM-30B mounted outside 15th Air Force Headquarters Operations Center and the plaque displayed under speed...Mach 16+. Well yeah, most ICBMs do :-) |
#33
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On Mon, 01 Dec 2003 05:32:03 GMT, Chad Irby wrote:
In article , ess (phil hunt) wrote: On Sun, 30 Nov 2003 18:06:01 -0500, Paul F Austin wrote: There've been a lot of religious arguments here about what "true supercruise" is and what airplanes can do it and it plainly has to mean "with ordnance aboard" or it means nothing at all. The F-22 is certainly the fastest airplane in the world with anything more than a tank full of cannon ammunition and possibly a pair of wing-tip missiles. SR-71? Not a lot of guns in SR-71s, and the YF-12s aren't even in existence any more, right? I don't believe an airplane needs ordnance aboard to supercruise, but the SR-71s have, like the YF-12s, been retired to museums. Mary -- Mary Shafer Retired aerospace research engineer |
#34
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Mary Shafer wrote:
I don't believe an airplane needs ordnance aboard to supercruise, but the SR-71s have, like the YF-12s, been retired to museums. Mary Well, one would think not, if one can think at all that is... -- -Gord. |
#35
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"Gord Beaman" wrote Mary Shafer wrote: I don't believe an airplane needs ordnance aboard to supercruise, but the SR-71s have, like the YF-12s, been retired to museums. Mary Well, one would think not, if one can think at all that is... The presence of ordnance is of some importance when comparing fighters, as we are in this thread. |
#36
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"Paul F Austin" wrote:
"Gord Beaman" wrote Mary Shafer wrote: I don't believe an airplane needs ordnance aboard to supercruise, but the SR-71s have, like the YF-12s, been retired to museums. Mary Well, one would think not, if one can think at all that is... The presence of ordnance is of some importance when comparing fighters, as we are in this thread. In the thread, yes, in that post, no. It might have been a poor choice of words on her part but she's a big girl who makes no bones about telling anyone else where the bear shat in the buckwheat so quit making excuses for her. -- -Gord. |
#38
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Yeah,someone ought to ask Paul Metz how fast the F-120 powered YF-23 would go
:-) M1.8 dry ain't too shabby.. |
#39
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"Scott Ferrin" wrote in message ... Maybe you missed that last line. Paul Metz is the chief test pilot, I think he'd know. I'd also think that he is not allowed to distribute still unreleased flight performance data. Which is why he said the maximum speed is classified. Did you even read what he said? So why hasn't Air Force or manufacturer released this information? And if Metz is allowed to release number 2.5, this would mean that real speed is considerably (at least M0.2) greater, which stretches the boundaries of belief even more. Despite what much of the media would have you believe fixed inlets mean zippo. No, they mean very much. It is certainly POSSIBLE to make a mach2+ plane with fixed intake, but this will do very bad things to inlet performance in other speeds (which are considerably more important). All your cited examples are such cases. Actually the Crusader III was excellent at low speeds as is the F-22. Excellent, as compared to what? Certainly inferior to even basic F8U, and massively inferior to any modern fighter. See above. It comes down to what is possible and what is sensible. If solving problems of Mach2+ flight regarding *serviceable combat aircraft* was so trivial as you make it sound, each and every modern fighter plane would go Mach3 or more. Where did I say that or even hint at it? For example he Despite what much of the media would have you believe fixed inlets mean zippo. Why haven't other manufacturers put these fixed "do-it-all" intakes to their fighters? Why they even bother putting variable intakes, even to planes which can't reach Mach 2.5? Engine thrust has not been a limiting factor in fighter top speed in like 40 years. Dry thrust certainly has been. Fighters don't reach their max speeds on dry thrust. Besides, though F-22 thrust-to-weight ratio is truly excellent, it's not unique. In addition to that, F-22 also has considerable stealth requirements. Radar-absorbing paints for example may not be very tolerant to high speeds. You mean like the stuff that was on the Blackbird? SR-71 was a maintenance nightmare, and large part of it was it's skin. It's hit 1.7 that they've released. In what load configuration? No external stores. They didn't say what they had inside. Could be they had a full load of fuel and test shapes for missiles or they could have had minimal fuel and nothing in the missile bays. Could be. IIRC, YF-22 with F119 engines went something like Mach 1.4 on supercruise (at least what was initially released). Remember, that combination was slowest of all 4 candidates. |
#40
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Which is why he said the maximum speed is classified. Did you even read what he said? So why hasn't Air Force or manufacturer released this information? Do you know what "classified" means? And if Metz is allowed to release number 2.5, this would mean that real speed is considerably (at least M0.2) greater, which stretches the boundaries of belief even more. Like I said- he's the test pilot and presumably gone 2.5 and knows. Why don't you ask *him* why he appears to be full of it in your opinion? Despite what much of the media would have you believe fixed inlets mean zippo. No, they mean very much. It is certainly POSSIBLE to make a mach2+ plane with fixed intake, but this will do very bad things to inlet performance in other speeds (which are considerably more important). All your cited examples are such cases. Actually the Crusader III was excellent at low speeds as is the F-22. Excellent, as compared to what? Excellent as compared to the fighters of the day. According to the test pilots it was far superior to the F-4 in air combat and if we'd have had it in Vietnam it would have "eaten them alive". Certainly inferior to even basic F8U, And that is based on what? Your opinion? and massively inferior to any modern fighter. I certainly hope so. See above. It comes down to what is possible and what is sensible. If solving problems of Mach2+ flight regarding *serviceable combat aircraft* was so trivial as you make it sound, each and every modern fighter plane would go Mach3 or more. Where did I say that or even hint at it? For example he Despite what much of the media would have you believe fixed inlets mean zippo. And what has that got to do with going Mach 3 or more? Do you think the inlet is the only thing that prevents an aircraft from reaching or sustaining Mach 3? Why haven't other manufacturers put these fixed "do-it-all" intakes to their fighters? Why they even bother putting variable intakes, even to planes which can't reach Mach 2.5? 2+ seems to be the magic number. They have to look at where the aircraft is going to spend most of it's time and then design it as such. For example pretty much every current fighter spends 95% of it's time below Mach one so to optimize the intake for Mach 2+ would be a bad idea. Aircraft that spend most of their time below Mach 1 or 2 but need but have the need to exceed Mach 2 more than a little bit need intakes that can do it but are still optimized for the lower speeds Thus the variable intake. An aircraft that is going to spend a significant amount of time about Mach 1 would have it's intake optimized for the higher speeds but still needs to account for the lower speeds. This is just based on observation but the two aircraft that I know of that fit the bill both have blow out doors to dump excess air. Not only that why would the F-22 have these blow out doors on the back AND those little spoilers right above the intake if it was just fixed like an F-16 or F-18? Engine thrust has not been a limiting factor in fighter top speed in like 40 years. Dry thrust certainly has been. Fighters don't reach their max speeds on dry thrust. My point exactly. Besides, though F-22 thrust-to-weight ratio is truly excellent, it's not unique. In addition to that, F-22 also has considerable stealth requirements. Radar-absorbing paints for example may not be very tolerant to high speeds. You mean like the stuff that was on the Blackbird? SR-71 was a maintenance nightmare, and large part of it was it's skin. Do you have any cites that mention the paint being a problem? I've never seen it written that it was. Could be. IIRC, YF-22 with F119 engines went something like Mach 1.4 on supercruise (at least what was initially released). Remember, that combination was slowest of all 4 candidates. I know. In my opinion they should have went with the F-23 with the F120s. But then maybe they felt the F-22 was more versitile. Why knows? |
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