米格25的重心位置

我大米格25. 我只知道不锈钢加电子管牛逼完了
米格25大马赫数飞行的时候配平就够喝一壶的了，应该不至于到灵敏这份上？

接近最高速度的时候基本等同火箭来自: iPhone客户端

比起火箭弹来说 还是很灵敏地

这段话？

首先，米格-25 虽然强调高空高速，但其起飞离地速度仅为 330 公里/小时，由此，我们可以发现，米格-25 的机翼升力系数是相当高的，其在起飞翼载达到 500 公斤/㎡的情况下仍旧可以做到如此小的起飞速度就是佐证，另外，据 1993 年美国空军上校盖瑞•L•阿德里奇在朱可夫斯基机场试飞米格-25PU 的经历来看，米格-25 起飞时操纵杆位移很大，这说明，米格-25 为了能够实现高空高速条件下的稳定飞行，在整体气动设计中选取了相当大的静安定度，其重心位置相当靠前，导致在低速（马赫数小于 1.5）时需要平尾提供相当大的力矩才能够顺利抬头。这一设计对飞机在中低速度段的机动性能影响相当的巨大，我们知道，当飞机的飞行速度超过音速以后，其气动中心会大大的前移，而气动中心的位置对改变飞机俯仰飞行姿态来说至关重要，米格-25 这种设计显然是为了使飞机在高速度段时不致出现气动中心前移至重心之前，导致飞机出现较大的低头力矩，从而导致危害飞机安全性而做出的。但如此靠后的重心设计，会使得飞机在中低速度段时的飞行品质变得极其呆板—在电传飞控还没有出现的年代，这种呆板显然不可能通过飞控的优化设计来改善，这使得米格-25 在中低速度段下俯仰方向的机动性能相当的低下。

　　同样的问题也出现在飞机的水平机动性能上，为了保障在高速状态下的航向安定性，米格-25 的平尾配平能力相当的强，强到了在低速状态下出现了相当程度的配平过剩现象，最终使得飞机在中低速度段的操纵响应迟缓。同样是出于保障高速状态下的航向安定性的考虑，米格-25 的垂直安定面面积十分的巨大，两个高耸的双垂尾和巨大的腹鳍设计使得飞机在高速时拥有足够的航向安定性，但在中低速度段，这样高的航向安定性显然是对飞机的机动性能有着相当的妨害的，这一系列为了保障飞机高速状态下飞行性能的设计，最终使得米格-25 在中低速度段上变成了一块飞行的砖头，稳态飞行有余，机动飞行不足。

这段话？

这有什么不能理解的。mig-25是专门为2马赫以上高速设计的，受当时的机械飞控技术所限必须牺牲低速时的操作性，也就是高速时机动性反倒好。这与为亚音速机动性优化的飞机正好相反。某些人认为Mig-25高速时是砖头是火箭完全的军盲认知，mig-25的2马赫动性完爆一切三代机。

LantianYY 发表于 2013-3-12 12:35
这段话？

这有什么不能理解的。mig-25是专门为2马赫以上高速设计的，受当时的机械飞控技术所限必须牺牲低速时的操作性，也就是高速时机动性反倒好。这与为亚音速机动性优化的飞机正好相反。某些人认为Mig-25高速时是砖头是火箭完全的军盲认知，mig-25的2马赫动性完爆一切三代机。

这有什么不能理解的。mig-25是专门为2马赫以上高速设计的，受当时的机械飞控技术所限必须牺牲低速时的操 ...
为高速飞行而优化当然明白，就是文章说得太模糊，你看一下我发的，一楼

注意，超音速后压力中心和焦点是要大范围后移的。在mig25没有电传的时代，超音速后焦点后移安定性超强只能用做小的机动，不存在什么超音速机动性完爆谁谁。

pl18 发表于 2013-3-12 13:45
注意，超音速后压力中心和焦点是要大范围后移的。在mig25没有电传的时代，超音速后焦点后移安定性超强只能用 ...
人家就是按照后移后最优设计的。反倒亚音速时机动性极差

fxwxjsj555 发表于 2013-3-12 15:24
人家就是按照后移后最优设计的。反倒亚音速时机动性极差
亚音速机动性差多半要归功于重量过大。气动中心后移，需要更大的配平能力，飞机俯仰操作会更加迟缓。

你们可真是死脑筋，看问题就是背一条定律就完事的？说白了没理解透。所谓的超音速气动中心后移是超音速的普遍规律这个没错。但是尾翼配平偏转加剧那是针对普通飞机说的。因为一般的非电传时代机飞机体重心都是靠前，也就是始终是低头的。速度高了之后气动中心后移造成低头力矩进一步增大所以配平力大了造成可用于机动的余量减少。而mig-25重心本身就是相对靠后的。亚音速飞行的时候反倒需要尾翼较大的偏转抑制抬头力矩，造成可用于机动的余量很小，机动性很差。而高速后气动中心后移与重心接近反倒不需要大的配平力了，尾翼控制余量增大，反而机动性变好了。

ericcui1 发表于 2013-3-12 15:35
亚音速机动性差多半要归功于重量过大。气动中心后移，需要更大的配平能力，飞机俯仰操作会更加迟缓。

你们可真是死脑筋，看问题就是背一条定律就完事的？说白了没理解透。所谓的超音速气动中心后移是超音速的普遍规律这个没错。但是尾翼配平偏转加剧那是针对普通飞机说的。因为一般的非电传时代机飞机体重心都是靠前，也就是始终是低头的。速度高了之后气动中心后移造成低头力矩进一步增大所以配平力大了造成可用于机动的余量减少。而mig-25重心本身就是相对靠后的。亚音速飞行的时候反倒需要尾翼较大的偏转抑制抬头力矩，造成可用于机动的余量很小，机动性很差。而高速后气动中心后移与重心接近反倒不需要大的配平力了，尾翼控制余量增大，反而机动性变好了。

fxwxjsj555 发表于 2013-3-12 15:46
你们可真是死脑筋，看问题就是背一条定律就完事的？说白了没理解透。所谓的超音速气动中心后移是超音速 ...

重心都在气动重心之前，这种情况下，重心越靠后所需的俯仰力矩越小，俯仰操作越灵敏。
如果重心在升力中心之后，你这飞机没有电传系统根本就没办法飞{:soso_e127:}

看了半天，应该是说米格25低速飞行是块板砖，高速飞行是火箭？那不还是板砖么？

ericcui1 发表于 2013-3-12 15:56
重心都在气动重心之前，这种情况下，重心越靠后所需的俯仰力矩越小，俯仰操作越灵敏。
如果重心在升力 ...
咋没发飞，平尾上翘，压住机头。只要受力平衡就可以飞。

静稳定度为负数……，这个时候要达到受力平衡，操作是相当复杂的，一点轻微的扰动都有可能导致失去稳定，没有计算机辅助主动控制技术，靠人根本就保持不了稳定飞行。

fxwxjsj555 发表于 2013-3-12 16:12
咋没发飞，平尾上翘，压住机头。只要受力平衡就可以飞。

静稳定度为负数……，这个时候要达到受力平衡，操作是相当复杂的，一点轻微的扰动都有可能导致失去稳定，没有计算机辅助主动控制技术，靠人根本就保持不了稳定飞行。

mig-25应该采用了比较原始的继电器之类的飞控，但是这方面的介绍很少。但是mig-25升限达到3万米以上，也就是说他在2马赫以上高速、在一般战斗机能够达到的2万米极限高度时仍然有很大的升力。也就是此时它的平尾还有富裕余量提供它抬头。这是一般战斗机达不到的。

ericcui1 发表于 2013-3-12 16:13
静稳定度为负数……，这个时候要达到受力平衡，操作是相当复杂的，一点轻微的扰动都有可能导致失去稳定 ...

mig-25应该采用了比较原始的继电器之类的飞控，但是这方面的介绍很少。但是mig-25升限达到3万米以上，也就是说他在2马赫以上高速、在一般战斗机能够达到的2万米极限高度时仍然有很大的升力。也就是此时它的平尾还有富裕余量提供它抬头。这是一般战斗机达不到的。

张俊 发表于 2013-3-12 11:53
接近最高速度的时候基本等同火箭
能做3g的机动，还能等同于火箭么？

Parasing 发表于 2013-3-12 12:02
比起火箭弹来说 还是很灵敏地
不仅比火箭灵活，机动性还超过SR-71。

fxwxjsj555 发表于 2013-3-12 15:46
你们可真是死脑筋，看问题就是背一条定律就完事的？说白了没理解透。所谓的超音速气动中心后移是超音速 ...
重心在气动前这是静不稳定的标志啊 ～～

重心在气动前这是静不稳定的标志啊 ～～
兄弟，推荐你去看看空气动力学，重心在焦点之前是俯仰静安定的好不好

mig-25应该采用了比较原始的继电器之类的飞控，但是这方面的介绍很少。但是mig-25升限达到3万米以上，也 ...
我也怀疑米格25的飞控，如果他静稳定度很大的话，高速的时候平尾配平的负担会很大，哪还能提供抬头力矩做3G的动作或是做到“响应灵敏”？这飞机太诡异了。我来试下召唤@lizyu

mig-25应该采用了比较原始的继电器之类的飞控，但是这方面的介绍很少。但是mig-25升限达到3万米以上，也 ...
帮忙@一下版主或是离子鱼什么的吧

LantianYY 发表于 2013-3-12 12:35
这段话？
1993年美国空军上校盖瑞•L•阿德里奇在朱可夫斯基机场试飞米格-25PU
-----------------------------------------------------------------------------
是美国空军中校盖瑞•L•阿德里奇，试飞的是米格25Up（教练机）
原报告如下：

FLIGHT TEST REPORT - MiG-25UP

Gary Aldrich and Stephen Henry

Originally published May 1995

30 June 93
Zhukovsky, Russia
Aldrich/Sultanov
Henry/Sultanov
Fuel Load: 8 metric tons (17,600 lb)

This is a composite flight report combining the evaluations of both Lt Col Aldrich and Lt Col Henry who flew the aircraft the same day.

FLIGHT BRIEFING:

Maximum G limits: 2.8 > 6 metric tons of fuel, 3.0 < 6 metric tons
Maximum Mach: 2.8 for this trainer version
Gear limit speed: 500 Km/Hr
Prohibited maneuvers: all "over the top" maneuvers, stalls, tailslides
Rotate speed: 250-270 Km/Hr
Liftoff speed: 310-330 Km/Hr
Briefed Profile:

Max A/B takeoff
Climb at 600 Km/Hr to 8-10 Km
Transfer trim to front cockpit for aileron rolls, level turns, minor maneuvering in pitch and possible "shallow loop" (low-G oblique loop).
Transfer trim to rear cockpit for "Buran" approach setup
Climb to 13-14 Km and accelerate to target velocity
Buran approach to Zhukovsky main runway, full stop


GENERAL OBSERVATIONS, GROUND OPERATIONS, STRAP-IN:

The aircraft is an "interceptor pilot training" variant with the instructor cockpit mounted below, and about five feet in front of, the normal cockpit. The RADAR is removed to make room for the instructor cockpit. Both evaluation crewmembers flew in this cockpit. The rear "normal" cockpit is configured as a standard MiG-25. Front cockpit canopy actuation is manual, hinged on the right side. The front cockpit occupant locks the canopy with a lever under the left sill after the crew chief lowers it to the rail. Both crewmembers received a thorough brief by a crew chief, accompanied by another maintenance person that spoke passable English. This was in contrast to the minimal brief for the previous day's flying and was probably driven by the near emergency Lt Col Aldrich experienced in the SU-17 high speed abort. Strap in to the MiG was straightforward as the harness is integrated with the seat. Shoulder straps and crotch straps met over the sternum where they were locked into a sturdy, but functional quick release buckle. After all connections are made, a ratcheting handle on the right side of the seat is actuated that tightens the harness. The shoulder straps can then be released from the locked position by pressing the lever on the left side of the seat to the right and aft. Oxygen and comm leads were identical to the SU-17, consisting of quick disconnect fittings secured to the harness with a small snap strap. As data would be collected for the Buran program, each crewmember was instructed in operation of the installed flight test data system. Cockpit controls for the system were mounted in a 2.5 in (h) x 10 in (w) panel mounted atop the glare shield, partially obscuring forward visibility. The controls consisted of ten toggle switches and four indicator lights. We were tasked to turn on the flight data recorder with the far left switch before taxi. The recording media for the system was contained in a large (10 in diameter) canister located below the main cockpit in a fuselage panel. The other switches we were allowed to touch were the trim transfer switch located in the center right of the main panel along with several other switches allowing instructor access to various systems; and the seat height adjust switch on the left cockpit sidewall. Engine start was conventional, using air pressure. The huge engines started quickly, with peak temperatures about 650 deg C. After receiving taxi clearance ("data on") we moved to the runway. Taxi did not appear to require unusual pilot skill and no rapid pedal inputs or wandering were noted. Just prior to runway entry we were held by a ground crewman with a red and white flag who did a cursory "last chance" inspection before waving us on to the runway for departure. One side note, Lt Col Henry shut down engines just after start because the alternate airfield was closed. This is very conservative since they had two runways and weather was only scattered clouds.

COCKPIT EVALUATION:

The front, or instructor cockpit was generally comfortable and allowed excellent visibility in all directions except the four to eight o'clock positions which were blocked by the large headrest on the K-36 ejection seat. Both curved forward windscreen panels caused significant distortion when compared to the view through the oval center forward panel. This did not seem objectionable during the landing phase. Instrument arrangement was standard for the aircraft evaluated on this trip. Flight instruments were grouped on the left side of the forward instrument panel with engine and fuel instruments to the right. A combined VVI and turn/bank indicator enjoyed a central location immediately in front of the pilot with the standard Russian "outside-in" ADI located to its left. A large drum-digital DME readout was installed above the VVI and to the left of a telelight panel with about 15 indicators. A small (0.75 in dia.) red master caution light was located below and left of the telelight and was unmarked. The Mach meter on the lower left of the panel read from zero to 3.0. A navigation instrument similar to our HSI was situated below the ADI and provided course and bank steering bars. A "standby" airspeed indicator was provided on the bottom left of the panel that was plumbed directly to the pitot tube, apparently bypassing any air data computation. It is not known whether this feature was production representative. Pitch trim was accomplished by fore/aft actuation of a rocker switch atop the tall control stick (if trim "control" was in your cockpit). Roll and yaw trim switches were located on the left forward instrument panel. A button on the right throttle actuated an intercom of excellent audio quality. There was no provision for "hot mike". Another button aft of the intercom switch was for transmitting over the radio. There was a speed brake slide switch located below the communication buttons. The throttles could be locked in the afterburner (AB) range by separate finger lifts similar to the mechanism that provided protection from inadvertent engine shutdown. The gear handle was located under a set of indicator lights on the lower left sub panel and was not mechanically connected to the rear cockpit handle, remaining in the "down" position the whole flight.

FLIGHT EVALUATION:

The pilot ran the engines up to 80% then moved the throttles to the AB range. There was no discernable AB lightoff and acceleration was not spectacular. Rotation (to about 10 degrees nose up) occurred around 250 Km/Hr with a large aft stick deflection with liftoff about 330 Km/Hr. We accelerated with a rapidly pulsating tone in our headsets to about 500 Km/Hr for climb. The tone is apparently analogous to the F4 AOA tone and is the only AOA indication available. The tone ceases as the gear were raised. Once in the work area the pilot told us to "take the trim" and we flew for about 5 minutes making 2g turns and aileron rolls in each direction. Aileron rolls were done at 500 and 750 Km/Hr. Stick forces and deflections were high. Maximum deflection rolls at 750 Km/Hr required about 60 lbs of lateral stick force (like pushing through molasses) and 8-10 inches deflection. The roll took 5 seconds at the lower airspeed and 6-7 seconds at the higher speed with no adverse yaw detected, though the nose did drop about 5-10 degrees below the horizon. Pitch forces were lighter, with 15-20 lb required for a 10 deg pitch change at the same airspeed. Turn performance was not evaluated due to the limited time available. The pitch damping was high and rates were comfortable with little overshoot. When asked to do a "shallow loop", the pilot said we did not have enough visibility with the clouds. Sultanov then took control to set up for the Buran approach. He lit the AB and accelerated in a 20 degree climb through the Mach and started a climb. He accelerated and S-turned to 1.3-1.5M while climbing to approximately 13.5 Km (very impressive climb performance). Initial climb rate was 5000 meters per minute. Fuel flow at this condition was about 15 metric tons per hour. The stick was held at nearly full aft travel all the while we were supersonic. Earlier, we were told that extended periods of supersonic flight are very tiring and are done on autopilot operationally. About 27 Km from the base, he retarded the throttles to idle and started down at about 1.2M. Initial VVI reading in the descent was 5000 meters per minute. He slowly bled this Mach number off until roughly 600 Km/Hr (subsonic) IAS then shutdown the left engine and descended on a 10-13 deg glidepath. Engine shutdown occurred at about 8 Km altitude. His aimpoint appeared to be the end of the runway and he made several adjustments with S-turns to lose energy. We began a flare at about 2000 meters and completed it just below 1000 meters and 500 Km/Hr. Below 500 Km/Hr the gear were extended. The rest of the flare and landing was normal, with touchdown at about 250 Km/Hr. Fuel remaining after the 0.5 Hr sortie was about 1 metric ton.

OVERALL EVALUATION:

The MiG-25 is a classic "point design" interceptor. Developed to counter the threat from the American XB-70 (the Russians say its target was the SR-71) it is a prime example of brute force engineering. The huge Tumansky engines provide impressive speed and altitude performance and overcome crude aerodynamics. The flying qualities and maneuver performance are terrible by today's standards, but are not objectionable when evaluated against the design mission. It is interesting to note that Sultanov said the MiG-31 flying qualities have not been changed from the MiG-25. Likewise, limited all-aspect pilot visibility is not a drawback when the requirement is to do high-speed, high-altitude, ground-controlled intercepts. For a purely defensive role, the short legs of the aircraft would be adequate for a dash-shoot-return profile. The fact that this aircraft is used to develop their space shuttle landing profile provides an insight to the aerodynamic performance of that vehicle.

STEPHEN A. HENRY, Lt Col, USAF
Deputy Commandant
Flight Test Navigator

GARY L. ALDRICH, Lt Col, USAF
Director of Technical Support
Flight Test Engineer

这样说法好象也不对吧

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LantianYY 发表于 2013-3-12 12:35
这段话？

这样说法好象也不对吧

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2013-3-13 10:57 上传

1993年美国空军上校盖瑞L阿德里奇在朱可夫斯基机场试飞米格-25PU  ---------------------- ...
帮忙@一下对米格25有研究的吧

这段话？
前面说重心靠前，后面又说靠后？？？？？

东线的幽灵 发表于 2013-3-13 09:53
帮忙@一下对米格25有研究的吧
说实在的，我过去对航空不是特感兴趣，对很多术语不懂。

我只出资料，请各位专家大侠给翻1下

fxwxjsj555 发表于 2013-3-12 15:46
你们可真是死脑筋，看问题就是背一条定律就完事的？说白了没理解透。所谓的超音速气动中心后移是超音速 ...
重心靠后，低速需要抬头力矩，这米格25岂不是成立放宽静稳定度的机机啦？是我理解错了吗？

fxwxjsj555 发表于 2013-3-12 16:12
咋没发飞，平尾上翘，压住机头。只要受力平衡就可以飞。
因为气动焦点在重心之前，气动扰动都是发散的，很容易就失控。这就是放宽静稳定度的飞机都要有电传操纵系统 的原因。

2013-3-13 10:56 上传

说实在的，我过去对航空不是特感兴趣，对很多术语不懂。   我只出资料，请各位专家大侠给翻1下
大概看懂了些，说是打开后燃室，推力加到80%，抬头保持10度迎角，然后在时速达到250的时候飞机离地。我词汇有限

说实在的，我过去对航空不是特感兴趣，对很多术语不懂。   我只出资料，请各位专家大侠给翻1下
大概看懂了些，说是打开后燃室，推力加到80%，抬头保持10度迎角，然后在时速达到250的时候飞机离地。我词汇有限

大概看懂了些，说是打开后燃室，推力加到80%，抬头保持10度迎角，然后在时速达到250的时候飞机离地。我词 ...
是先转速80，然后就打开加力，到时候速度250抬起机头保持10迎角，330离地。

是先转速80，然后就打开加力，到时候速度250抬起机头保持10迎角，330离地。
我凭印象翻的……

东线的幽灵 发表于 2013-3-13 21:17
我凭印象翻的……
正常，我也是拿金山词霸跟着凑合着看

自己顶吧，坐等大神