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#21
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Mary Shafer wrote in message . ..
On Tue, 14 Oct 2003 22:41:47 +0100, "José Herculano" wrote: No jet ever made (or that ever will be made) had enough power. Possible exception of the F/A-22 Raptor under current conditions... How about the big black twin two-seater I used to work on? Whatever its limitations, lack of thrust wasn't one. It's not every airplane that can burn 85,000 lb of fuel in just over an hour, you know. Mary Come on, Mary; an F4 on the deck burns at the rate of 1500 a minute, 90,000 an hour, and even goes a lot faster than the 71 down there. Of course, it'll be dry in about 7 minutes (clean), but it's a great ride to bingo. Once I took an F4D up for a test hop for a rudder actuator change. (Fly; if it's ok, land.)The original one had cracked and leaked red fluid all over . . . . the crew chief asked me to get the residual hydraulic fluid out of the aft section. Flat out around 750 KIAS at 100 ASL off shore of Kunsan Korea did a good job of blowing it dry. The fuel state visibly reduces, too. Walt BJ |
#22
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James Woody wrote:
I did not see it listed on the web site. http://www.combatairmuseum.org/aircraft.htm Any other information on this bird? Woody Dug through my photos from the trip. 66-268 looks to be a C/D with a Mig kill on 12 Oct 1972. Left side painted as it was when assigned to SEA, right side painted when assigned to KS ANG. The aircraft is decked out for air defense with drop tanks, 4 x sidewinder, and 4 x sparrow. Don't have access to binary groups through my ISP or I'd post photos. If you are interested in photos, I can email them. (I remove the NOTAT?) MAH |
#23
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On Wed, 15 Oct 2003 15:49:15 -0500, catsrus
wrote: Mary - Is there any sensible reason why your airframe was retired from service when it still seemed to be viable? No agency mission. We didn't have any experiments that justified keeping it going. Was it only a money issue or is there more to it than that? I suspect that money was part of the decision, since it usually is, but it was probably more of an effect than a cause. Mary -- Mary Shafer Retired aerospace research engineer |
#24
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#25
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On Tue, 21 Oct 2003 01:14:57 GMT, "Doug \"Woody\" and Erin Beal"
wrote: On 10/20/03 3:06 PM, in article , "Mary Shafer" wrote: Incidentally, most people know that the SR-71 used the dipsy-doodle to convert potential energy to kinetic energy (altitude to velocity) through the transonic region. Many people think it could only go supersonic if it dipsy-doodled, but that wasn't the case. It could get supersonic flying straight and level, too. However, as soon as it did, it pretty much had to slow down and go look for the tanker. This took a little longer than seven minutes, though. Is the "dipsy doodle" what most fighter pilots refer to as the Ritowski climb? I don't know, as I don't know exactly what the Ritowski climb is. I think it is, though. Essentially, the SR-71 climbs at constant qbar (400 KEAS) to Mach 0.9, then descends at a constant rate to Mach 1.25 (450 KEAS at 30,000 feet), and then climbs again at a different constant qbar (450 KEAS) to cruise. I would assume so since that's the recommended procedure for getting most supersonic aircraft going high and fast quickly and without running out of gas. Seems reasonable to me that it would work generally, not just for the SR-71. Please elaborate. And what were the specifics of the profile for the SR-71 (as long as it's not classified, of course)? Naturally, I'm here and my Dash-1 is there, so I can't produce the exact numbers unless they're in the Researcher's Handbook. Let me go look. OK, I'm wrong, I do have the Dash-1, which was hiding on the wrong shelf. I'll still going to look first in the Researcher's Handbook, except that it doesn't have an index. An index won't help, though, because "dipsy doodle" isn't exactly an official USAF term. Nada. OK, here it is from the Dash-1. It's pretty long, but I thought you'd prefer the exact description, not my briefer version of it. It's "a climb-and-descent maneuver". You'll have to imagine the typography, boxes, and indentation yourself, though. TRANSONIC ACCELERATION PROCEDURE Transonic acceleration is accomplished at either a level altitude or during a climb-and-descent maneuver. NOTE The climb-and-descent acceleration is recommended for best specific range (NM per pound of fuel used). Level Acceleration A level acceleration to intercept the supersonic climb speed schedule can be made at refueling altitude, normally 25,000 feet. When ambient temperatures are near or lower than standard, less time and distance are required to intercept the climb speed schedule than the climb-and-descent procedure. The total range penalty is small under these conditions. Start the acceleration with minimum afterburner. Complete course changes while subsonic so that the additional power required for turning will not diminish the power available for transonic acceleration. Set maximum power at Mach 0.9. Gently increase pitch to climb attitude near 430 KEAS. A smooth technique is required, as 450 KEAS is only slightly more than Mach 1.1 at 25,000 feet and is still within the critical thrust/drag speed range which begins near Mach 1.05. WARNING Airspeed may increase rapidly after Mach 1.1 is reached. Reduce power (below Military, if necessary) to avoid high airspeeds. Do not use excessive load factors to prevent exceeding 450 KEAS, The procedure can be used at another altitude; however, when lower, the transition to 450 KEAS climb attitude must be made in the unfavorable speed range from Mach 1.05 to 1.10. At higher altitudes, the transition through this speed range can be completed before starting the climb, but less thrust is available. If ambient temperature increases, thrust decreases and the time, fuel, and distance penalty for using the level acceleration procedure is greater. Climb-And-Descent Acceleration The climb-and-descent procedure requires less fuel to intercept the climb speed schedule than the level acceleration when ambient temperatures are warmer than standard. NOTE The climb-and-descent procedure is recommended for best specific range (NM per pound of fuel used) at all temperatures. WARNING Although angle of attack increases during the subsonic climb, pitch attitude must decrease to avoid dangerous flight conditions. Failure to monitor and control attitude, speed, and angle of attack can result in approach to pitch-up conditions. Start the acceleration with minimum afterburner power. Intercept Mach 0.9. Set maximum afterburner at 30,000 feet for the remainder of the acceleration, observing the 300 KEAS restriction. At 33,000 feet, increase speed to at least Mach 0.95. This speed is slightly above the start of the drag rise region. Make a smooth transition to establish a 2500 to 3000 fpm rate of descent. NOTE Engine stalls during the subsonic climb may indicate a potentially dangerous flight situation. Stalls can result from low CIP or high distortion in the inlet associated with aircraft operating beyond established flight limits. Refer to Subsonic Compressor Stalls, Section III. After establishing the descent rate, maintain attitude until initiating climb. Avoid higher rates of descent since the usual result is altitude penetration below 29,000 feet and high fuel consumption. When using the climb-and-descent procedure, it is important to exceed Mach 1.05 early in the descent, and to avoid turning until the climb is established. Begin the transition to climb near 435 KEAS so as to intercept 450 KEAS while climbing. WARNING - Airspeed may increase rapidly after Mach 1.1 is reached. Reduce power (below Military, if necessary) to avoid high airspeeds. Do not use excessive load factors to prevent exceeding 450 KEAS. - In turbulence, reduce climb speed as specified in Section VII, Operation in Turbulence. This is just over a page, but the SUPERSONIC ACCELERATION PROCEDURE is two and a third pages. Mary -- Mary Shafer Retired aerospace research engineer |
#26
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I'm curious why the 450 limit is such an issue ... your quote implies bad
things happen if it's exceeded. I realize the SR had a relatively low q-limit, but I didn't believe it that low. Was another factor the issue? R / John |
#28
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Just out of curiosity, Woody, what is the fastest you've had the Hornet in
KIAS and IMN? I had a TPS guy claim 800/1.8 for the C, but I think he was feeding me pure unadulterated BS. In my brief exposure, I was astounded by its LACK of speed. R / John |
#29
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#30
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Re the 'Rutowski' climb path. We got the word from Eglin AFB around
1965 and used it in the 104A with the old J79-3b engine. It worked nicely but had to be flown precisely to avoid wasting fuel. When we got the J79-19 it was such a thrust improvement (17900 vice 13850) we didn't bother. One nifty climb profile was to accelerate to 600 KIAS at say 1000 AGL after T/O (height optional as long as you didn't get caught) about a mile or so off the end of the runway and then maintain 600 to crossover to M2.0. Made for quick intercepts and was quite exhilirating! This was a real case of a new engine (F4E/S)in an old (1956) airframe. Walt BJ |
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