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Aviation History
1954
1954 - 2301.PDF
242 FLIGHT, 20 August 1954 This picture is included to show the upsweep of the wing-tips in flight, and particularly the vortex generators. Briefly, these tiny surfaces take energy from the free airstream and transfer it to the boundary layer. The effect is to reduce turbulence and delay the onset of high speed-stall effects. BOEING B-47E In the Air . . . swept wing has rome well-known characteristics of which the most apparent is the rolling effect resulting from yaw (i.e. the applica tion of rudder). Small changes in lateral trim are made with the aid of conven tional aileron trim-tabs, but a touch of rudder or rudder trim may be the better way of obtaining correct lateral trim. For die same reason, powerful aileron control and big aileron deflections are called for, and at high angles of attack with flap down the "flaperon" effect has therefore been employed. The long, flexible wings are the cause of progressively falling aileron effect as speed increases above that for normal cruise. At medium altitudes and with speeds of more than 400 kt the rate of roll is less than 10 deg/sec. A flutter limitation is also placed on die aircraft, but it is important to get these superficially alarming things into perspective. This aircraft is designed to do a specific bombing job as efficiently as possible, and the limitations referred to could only occur outside its normal operating regime. A parallel would be to complain diat a racing car was too hard-sprung for slow driving over pave. At its operating speeds and altitudes— and diey are bodi very high—the B-47 has light and adequately effective controls, although it is no good expecting to pull a lot of g in turns when it is making straight for an objective with a full load. The vortex generators on die wing outer and upper surfaces to which reference was made in Flight a few weeks ago have helped to delay the onset of buffeting. At die risk of surpassing even a Hollywood epic with the number of credits and build-ups before getting rolling, I must mention one more aspea of performance—namely, that widi engines out. For example, with a take-off weight of 185,000 lb and without water or rockets, the B-47 can lose one engine (and marginally any two) while bodi flaps and gear are down, and get away with it— in both senses. At the lower weights, such as would obtain when returning from an operational sortie, the aircraft will fly on two engines. There are two emergency occasions when correct procedure calls for die stopping of four out of six engines. The first is for maximum endurance when holding at die end of a sortie; the second is for an emergency landing with brakes and tail-chute out of action. In spite of the hurry to get off, a full external check was made by die captain before he entered the aircraft. This took some 20 minutes and followed a complete inspection by ground crew men. Personally, I stopped inspecting after standing up too quickly in a wheel well. Each inspection door—and diere are dozens of them— had a tiny putty seal across it with an impression of die individual inspector's identification marks clearly stamped upon it. The inside check before starting engines was another lengthy business, involving both pilots. Then mere were all the pre-taxi checks and, somewhat shorter, the pre-take-off drill. With the aid of my periscope (provided with power for eleva tion and traverse when die J47s got turning) I could follow all ground movement very well. I had been unable to detect the actual starting-up of engines either by noise or by feel, but could hear the combined noise very remotely when taxying. I had heard die pilots call for starts on 4, 5 and 6, then 3, 2 and 1; they were using die external intercom plug and talking to "ground." When cleared to taxi we moved down the long line of odier B-47Es and RB-47Es, occasionally making surprisingly sharp turns. The brakes when checked were extremely powerful and nearly caused me to get my face wedged in the rubber face-piece of the periscope. I could hear everything very clearly, thanks to the most perfect \ Moving back from the nose position, one crawls "on edge" along a narrow port-side gangway, and has this worm's-eye view of the pilot and co-pilot in their tandem seats above. intercom I have ever used; it was crystal clear, and completely widiout background noise or breadiing. Each man is provided with an effective volume control. The navigator's microphone switch is a foot-operated press-button which I found very con venient and much preferable to a switch on one's mask. The moment to take off finally arrived, and the engines at full bore could then be heard as a distant mighty rushing noise. Initial acceleration felt negligible; and even when the voice of the second pilot came dirough, calling the speeds, we did not seem to be moving very fast. He cut in at 80 kt and, with die very smallest nose-up change of attitude, we unstuck smoothly at about 115 kt. Both sets of wheels must have come off the ground almost simul taneously, and diey took about ten seconds to lock up. Without any conscious effort or pronounced nose-up attitude Looking, Irish-like, at where the internally-stowed take-off assistance rockets are not on the later marks of the B-47. A jettisonable external harness of 33 x 1,0001b bottles is now employed, and the General Electric J47-GE-23 engines have water/methanol injection (6,500 lb thrust). Seen with the author are (left) Rod Randall, the pilot, who is supervisor of production test flying at Boeing, Wichita, and (right) the co-pilot/observer, Maurice Norum.
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