它快的不是引擎，是整條管路The speed is in the duct, not the engine
八個機制，每個都附一個可以拿去跟人爭論的數字。Eight mechanisms, each with one number you can argue with.
A推力分配：54 / 28.4 / 17.6Thrust split: 54 / 28.4 / 17.6
Mach 3, full afterburner
這張圖是這一頁最重要的一張：多數人以為黑鳥的祕密在 J58，其實一半以上的推力來自把超音速空氣「先壓成靜壓」的進氣道。This is the page's most important chart: most people think the secret is the J58. Over half the thrust comes from the inlet slowing supersonic air before it reaches the engine. [wiki]
B八個機制Eight mechanisms
術語都當場定義Terms defined in place
推力不是全部來自引擎Most of the thrust is not from the engine
在 3 馬赫全後燃器狀態下，推力分配是：進氣道 54%、噴嘴 28.4%、引擎本體只有 17.6%。換句話說，黑鳥的性能是「整組進氣—引擎—噴嘴」一起算出來的，引擎只是這條管路裡的一個零件。At Mach 3 in full afterburner the thrust splits like this: inlet 54%, ejector nozzle 28.4%, engine 17.6%. The Blackbird's performance came from the whole inlet-engine-nozzle system; the engine was one component in the duct.
錐體與「不啟動」The spike and the 'unstart'
進氣錐前後移動，把斜震波固定在該在的位置，讓超音速空氣在進入引擎前就被壓縮。控制沒跟上時，震波會突然彈到進氣口外——這叫 unstart，推力瞬間消失、機身猛偏，座艙裡會像被撞了一下。1980 年代換成數位控制（DAFICS）才把這件事壓下來。A translating spike holds the shock wave where it belongs so supersonic air is compressed before it reaches the engine. When the control lagged, the shock would jump out of the inlet — an 'unstart' — killing thrust and yawing the aircraft violently. Digital inlet control (DAFICS) in the 1980s largely fixed it.
JP-7：點不著的燃料JP-7: fuel that will not light
JP-7 的閃點高、幾乎不揮發，所以在高溫油箱裡不會自己燒起來；代價是很難點火，起動時要打進三乙基硼（TEB）這種一接觸空氣就自燃的液體。燃油同時是冷卻劑：先流過機身與引擎帶走熱，才進燃燒室。JP-7 has a high flash point and barely evaporates, so it will not ignite in a hot tank — at the cost of being hard to light: starting requires triethylborane (TEB), which burns on contact with air. The fuel doubles as coolant, soaking up heat from the airframe and engine before it is burned.
85% 鈦合金，還有蘇聯的鈦85% titanium — some of it Soviet
機體 85% 是鈦。鈦難焊、難加工，洛克希德一度有 80% 進料被判定污染退貨；焊接要用蒸餾水，工具不能鍍鎘。更諷刺的是，CIA 透過第三國的空殼公司，從蘇聯買進部分鈦材——用對手的金屬造對手的偵察機。85% of the structure is titanium. It was hard to weld and machine — at one point 80% of delivered titanium was rejected as contaminated; welding needed distilled water and no cadmium-plated tools. The CIA also bought part of that titanium from the Soviet Union through front companies: the enemy's metal in the aircraft built to spy on them.
在地面漏油，在空中密合It leaks on the ground and seals in flight
機身蒙皮在 3 馬赫會加熱到數百度、膨脹好幾公分，所以面板在地面只能鬆配。結果就是起飛前會滴油——但滴的量不足以讓你必須立刻加油。真正的原因是起飛只帶部分燃油，保護輪胎與煞車，並且確保單發失效還能離地。Skin temperatures of several hundred degrees expand the airframe by inches, so panels are fitted loose on the ground. Hence the famous fuel drips — but not enough to require immediate refuelling. The real reason for the early tanker rendezvous is a partial fuel load: to protect tyres and brakes and to guarantee a take-off on one engine.
看星星導航Navigating by the stars
星光慣性導航（ANS）透過機背一塊石英窗追蹤星體，修正慣性漂移，還能自動指向相機、控制感測器。前黑鳥飛行員說，在 3 馬赫時它的橫向誤差可以壓在 300 公尺等級。The astro-inertial navigation system tracked stars through a quartz window in the spine, correcting inertial drift and driving the cameras and sensors automatically. Former crews put its drift at roughly 1,000 ft at Mach 3.
黑色是散熱，不是隱形Black is for heat, not stealth
黑漆的用途是提高輻射散熱效率，讓蒙皮溫度低一點。雷達截面積大約 10 平方公尺，是一架小飛機的等級，跟 B-2 差好幾個數量級。它的生存靠的是高度＋速度＋短到來不及反應的攔截窗口。The black paint radiates heat away, lowering skin temperature. Radar cross-section was around 10 m² — a small aircraft, orders of magnitude worse than a B-2. It survived on altitude, speed and an intercept window too short to exploit.
輪胎與減速傘Tyres and a drag chute
輪胎含鋁、充氮氣，一個 2,300 美元，大約 20 個架次就要換。落地速度超過 170 節，所以落地後要放減速傘——這不是表演，是煞車與輪胎的壽命問題。Aluminium-alloy tyres inflated with nitrogen cost $2,300 each and lasted about 20 sorties. Landing speed exceeded 170 knots, so a drag chute was standard — not for show, but for brake and tyre life.
C規格表Specifications
SR-71A
| 機長Length | 32.74 m (107 ft 5 in) |
| 翼展Wingspan | 16.94 m (55 ft 7 in) |
| 機高Height | 5.64 m (18 ft 6 in) |
| 翼面積Wing area | 167 m² (1,800 sq ft) |
| 空重Empty weight | 30,600 kg (67,500 lb) |
| 最大起飛重Max take-off | 78,000 kg (172,000 lb) |
| 發動機Engines | 2 × Pratt & Whitney J58, 145 kN each |
| 巡航Cruise | Mach 3.2, 24,000–26,000 m |
| 作戰半徑Combat radius | 約 5,400 km（含空中加油） |
| 機組Crew | 2（飛行員 + RSO） |
作戰半徑隨任務剖面與加油次數變化很大，這裡給的是含空中加油的常用說法。Combat radius varies heavily with profile and tanking; the figure given is the usual with-refuelling case.