? Photo jpg B47 Approach DRAG CHUTE ?
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? Photo jpg B47 Approach DRAG CHUTE ?
This is about Boeing's first problems with the TURBOJET's "spooled-up" requirement during approach. Can anyone provide the photo /link to a jpeg to the old photo's of the USAF's B47, in flight during approach, with the Approach Drag Chute DEPLOYED.
Photos are published in the following magazine and book (but I can't locate the same images on the web):
_Flying Safety Magazine_, August, 1955; pg 25:
[Photographs show four images of the B-47 in flight with the approach drag-chute deployed.]
Photos are published in the following magazine and book (but I can't locate the same images on the web):
_Flying Safety Magazine_, August, 1955; pg 25:
[Photographs show four images of the B-47 in flight with the approach drag-chute deployed.]
“Approach Chute -- The landing speed of the B-47 jet bomber has been considerably reduced through the use of an approach drag chute…. The ’47 has used a parachute for braking purposes [after landing] for six years. The new parachute will not take the place of the 32-foot landing deceleration chute, but will be additional equipment, deployed in the air to permit a steeper descent for landing approach.
“The new parachute is approximately 16 feet in diameter … Using this approach control device ... makes for better control on landing approaches ... The use of parachutes permits pilots to maintain engine power during landing, thus assuring engine response ...”
Bill Cook, _Road to the 707_, pg 189, shows four earlier images with the caption “The new parachute is approximately 16 feet in diameter … Using this approach control device ... makes for better control on landing approaches ... The use of parachutes permits pilots to maintain engine power during landing, thus assuring engine response ...”
"XB-47 Drag Chute Landing Sequence -- Moses Lake, 1948"
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Having a few friends who actually flew the 'ole B47, the drag 'chute in flight, (on approach) was a regular occurance, early on.
Later on, ops were changed, and the 'chute was used after landing only.
Later on, ops were changed, and the 'chute was used after landing only.
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In the old days, when Brize Norton was a sea of silver B.47's, they appeared to use the chute all the time on the approach. I never saw one landing without, although that's only what I saw.
Yes, someone has told me how to do it thanks, but it seems the photos have to be on the Internet somewhere first, so I'm afraid it's in the "too difficult" box for me.
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Photobucket images help concept of "Spooled-Up"
From slot #2, BEagle shows the Approach Drag Chute, and has put that jpg on the web at Photobucket's link:
http://i14.photobucket.com/albums/a341/nw969/B47.jpg
THANKS BEagle, that photo adds to the background on the TURBOJET's "engines Spooled-Up" concept. I had earlier put the turbojet's Engine Acceleration Curves on the web at Photobucket,
http://s675.photobucket.com/albums/vv118/IGhhGI/
but the B47 photo helps teach the importance of DRAG during turbojet's approach (to ensure "spooled-up").
Here's Bill Cook's recollection of this solution to the weaknesses discovered during Boeing's first Turbojet project:
_The Road to the 707_, pgs 186-90:
“Following the company tests, the Air Force was to fly the XB-47 to determine its military ... suitability and ... performance, stability and control, bad characteristics.... During the course of this testing several design defects were discovered. The most obvious deficiency ... was in making landings with precision in stopping distance. The ability to make corrections to the glide path was poor. The drag of the airplane was inherently low because of the high span slender wing. The flaps were designed to have low drag in order to facilitate taking off with a maximum load. The placement of the bicycle landing gear necessitated full flaps on take-off. But what was useful and beneficial to take-off was detrimental to landing when high drag was preferred to steepen the descent without increasing speed. On approach the glide angle was fairly flat even with the added drag of the landing gear. The engines required a long time to accelerate to high thrust from idle rpm, as the engine fuel control would increase the fuel flow only slowly to protect the engine compressor from surging, when the thrust momentarily quits with a loud bang. Correcting for a low approach by adding thrust was therefore slow. Carrying extra airspeed was not advisable, as the airplane would be nose down and the front gear would touch first, causing a bounce back up into the air. Once on the runway the brakes could not be applied until there was some weight on the wheels. The air drag on the runway was low, and therefore the distance before heavy braking could be applied was long....
... the German inventor of the ribbon chute, Professor Theodore Kanake, who was one of the German scientists brought to the U.S. shortly after the war. The ribbon chute was designed to be strong at very high speeds....
... The Air Force later added another small chute that was deployed on approach so that higher engine rpm could be maintained. This unorthodox means of inducing drag saved the XB-47 program, for attempts to train operational pilots without the chutes would have resulted in severe problems....
“... From this experience a lot was learned about landing a jet airplane. The reason why it had been easy to land previous airplanes that relied on piston engines and propellers was that the propeller with a closed throttle produced high drag, enabling a steeper glide path. The piston engine was quick to accelerate, and the blast of the slipstream on the flaps added high lift, both of which helped the pilot correct for a low and slow approach.... [Page 189 shows four photographs of the B47 with the chute deployed: during approach, flare, landing, and rollout on the runway.]
“... at the time there were no readily available alternatives to address the landing problem, and the program might have died on the vine. Although the parachute saved the day, at the start of the program no one would have bet money on such an unorthodox solution....” [Excerpt ended on page 190.]
http://i14.photobucket.com/albums/a341/nw969/B47.jpg
THANKS BEagle, that photo adds to the background on the TURBOJET's "engines Spooled-Up" concept. I had earlier put the turbojet's Engine Acceleration Curves on the web at Photobucket,
http://s675.photobucket.com/albums/vv118/IGhhGI/
but the B47 photo helps teach the importance of DRAG during turbojet's approach (to ensure "spooled-up").
Here's Bill Cook's recollection of this solution to the weaknesses discovered during Boeing's first Turbojet project:
_The Road to the 707_, pgs 186-90:
“Following the company tests, the Air Force was to fly the XB-47 to determine its military ... suitability and ... performance, stability and control, bad characteristics.... During the course of this testing several design defects were discovered. The most obvious deficiency ... was in making landings with precision in stopping distance. The ability to make corrections to the glide path was poor. The drag of the airplane was inherently low because of the high span slender wing. The flaps were designed to have low drag in order to facilitate taking off with a maximum load. The placement of the bicycle landing gear necessitated full flaps on take-off. But what was useful and beneficial to take-off was detrimental to landing when high drag was preferred to steepen the descent without increasing speed. On approach the glide angle was fairly flat even with the added drag of the landing gear. The engines required a long time to accelerate to high thrust from idle rpm, as the engine fuel control would increase the fuel flow only slowly to protect the engine compressor from surging, when the thrust momentarily quits with a loud bang. Correcting for a low approach by adding thrust was therefore slow. Carrying extra airspeed was not advisable, as the airplane would be nose down and the front gear would touch first, causing a bounce back up into the air. Once on the runway the brakes could not be applied until there was some weight on the wheels. The air drag on the runway was low, and therefore the distance before heavy braking could be applied was long....
... the German inventor of the ribbon chute, Professor Theodore Kanake, who was one of the German scientists brought to the U.S. shortly after the war. The ribbon chute was designed to be strong at very high speeds....
... The Air Force later added another small chute that was deployed on approach so that higher engine rpm could be maintained. This unorthodox means of inducing drag saved the XB-47 program, for attempts to train operational pilots without the chutes would have resulted in severe problems....
“... From this experience a lot was learned about landing a jet airplane. The reason why it had been easy to land previous airplanes that relied on piston engines and propellers was that the propeller with a closed throttle produced high drag, enabling a steeper glide path. The piston engine was quick to accelerate, and the blast of the slipstream on the flaps added high lift, both of which helped the pilot correct for a low and slow approach.... [Page 189 shows four photographs of the B47 with the chute deployed: during approach, flare, landing, and rollout on the runway.]
“... at the time there were no readily available alternatives to address the landing problem, and the program might have died on the vine. Although the parachute saved the day, at the start of the program no one would have bet money on such an unorthodox solution....” [Excerpt ended on page 190.]
