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Martin XB-48
- Thread starter Mark Nankivil
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Steve Pace
Aviation History Writer
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I had missed this. Interesting to be sure. Thanks, Mark! -SP
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Steve Pace
Aviation History Writer
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XB-48 Design Patent. -SP
Hi
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Wahubna said:
A particular eBay seller was selling literally TONS of material stamped "Lockheed" over the last couple of years. It seems that Lockheed had quite an extensive data base in the 1950s containing, not just their own reports, but also official military reports and lots of reports from the competition. How these landed in their hands is unsure, but it is likely that the barriers between the companies were not so tightly sealed as today and that each company was given access to the designs of the competition for comparison (perhaps when the tender was over).
archipeppe
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My personal contribution (also available on the next Steve Pace's book on U.S. X airplanes).
Ciao
Giuseppe
Ciao
Giuseppe
foiling
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Giuseppe, this particular aircraft has never really caught my interest much, however your magnificent illustration is so spectacular that i feel like i am looking at the most exquisite diamond ring in an exclusive store. Well done, and thanks for sharing.
Skyblazer said:
I got a *few* of these items. The non-Lockheed items broke out into three kinds:
1) Original brochures & such, obtained who-knows-how.
2) Data collected and collated by Lockheed into their own files, sources unknown
3) Reports printed from microfilm, obtained *from* the USAF. Looks like pretty much everything the USAF got, they photo'ed onto film and put in storage (a collection I'd give someone else's left nut to be able to peruse). How Lockheed got 'em I don;t know, but it might have been as simple as just requesting them.
THE GLENN L. MARTIN COMPANY
PUBLIC RELATION DEPARTMENT
BALTIMORE, MARYLAND
RELEASE # 1479
Within the past few months the mighty XB-48 has been added to the U. S. Air Force’s arsenal of fighting aircraft. The XB-48, built by The Glenn L. Martin Company, Baltimore, Maryland, is the world’s largest high-speed jet-bomber of conventional exterior design — though in some respects it remains highly unconventional.
Rated a lightweight among Air Force bombers, the XB-48 is powered by six General Electric J-35 gas turbine engines capable of delivering a total of 24,000 pounds of thrust. This power potential, when converted into more familiar horsepower, would about equal the combined energy of 290 average passenger automobiles.
With information on its performance characteristics still largely under wraps due to military security regulations, the Air Force has admitted that the XB-48 flies in the "500 mile per hour" class. Because of its speed, which is great, indeed, for a bomber, an entirely new development in landing gear was designed — a tandem type, in which the main wheels like those of a bicycle are located one behind the other.
Tricycle landing gear, found on most aircraft today, was entirely impractical for the XB-48, for with tricycle gear, the main wheels fold into wing wells after the craft becomes airborne. With the XB-48, there is not sufficient room in the wings for large wheel wells because the wings are designed for high speeds and had to be extremely thin. By arranging for the tandem gear to fold into the fuselage of the XB-48, the desired wing design became practical.
Obviously, some wing support is necessary when the new bomber is stationary on the ground. Hence, small wheels are located midway under each wing, and fold into the nacelles of the outboard engines when the craft is in flight.
Viewed directly from the front, there is a noticeable droop to the wings, particularly toward the tips. However, in a fast taxi run, the droop becomes reversed – to a degree where the outrigger wheels are lifted from the ground. From this point on, the XB-48 moves forward on its two "bicycle type" gear, and a strange sight it is, for at a distance the small wheels are not easily visible. In a fast run or actual take-off, with outriggers already off the ground, lateral stability is supplied by the lift of the wings.
So complete a departure from conventional landing gear types required a great deal of advanced planning and testing. Early in design stages, a Martin B-26 Marauder was secured from the Air Force and fitted up with tandem main wheels and outrigger balance wheels. Then dozens of landing and take-off tests were made. Movies and pilot reports were studied thoroughly before the decision was made that the new gear would function in a completely satisfactory manner on the XB-48.
Because of high temperatures necessarily present in the operation of a modern jet aircraft like the XB-48, certain parts had to be designed to withstand unusual heat. Therefore, stainless steel was used for vital components of the jet engines; for anti-icing ducting; for a number of flexible connections, and in other installations where metals must give high performance while being subjected to temperatures of 800° F. and more.
The XB-48 packs a lethal punch — more than 10 tons of bombs, over a combat radius of hundreds of miles, and when necessary it can take its load to 40,000 feet where danger from flak is greatly diminished.
In building the first in the unprecedented time of thirteen months, the Martin Company developed a streamlined production technique which won high praise in the industry and from the Air Force’s top command.
The engineering staff, which at its peak numbered 137, moved right into the plant, adjacent to the shop. A separate accounting section was established, its files and desks almost touching the engineers' drawing boards. Blueprints were made on the spot in "while-you-wait" style and materials ordered at the same time the designs were being drawn.
The XB-48 mock-up was only a few steps away, making possible instant checking of changes of placement of parts. The plane itself was built in the same section of a huge assembly building, a few hundred feet from the project offices. To add even more speed, a separate raw stores was established, stocking only raw materials and parts need on the XB-48.
This streamlined, simplified system boiled the entire project down to its essentials — kept each part moving at maximum speed and efficiency toward its proper place in the finished airplane.
An engineer would sketch a simple plan for a special part. Instead of sending it through channels, he'd walk a few feet to the shop, lean over a machine and discuss it with the man who would make the part.
If no tooling were necessary, work on the part would begin immediately. If a tool were required, both men would walk over to a tool designer, explain their problem, and the three of them would work out the necessary tool. Then tool and drawing would be taken to the shop for manufacture. Then the part was ready, it would be taken immediately to the airplane, where the man who designed it and the man who made it could watch it installed. All of which adds up to one of the most unorthodox airplane production programs ever attempted — and, also, one of the most successful.
Two of these great new bombers have been delivered to the Air Force and are now undergoing advanced testing at Wright-Patterson Field, Ohio. The second is expected to show even more advanced performance then the first.
They have a gross weight of 102,600 pounds; an empty weight of 58,500 pounds; wing area of 1,300 square feet; span of 108'4"; length of 85'9"; and height of 27'6". Crew is 3 men.
PUBLIC RELATION DEPARTMENT
BALTIMORE, MARYLAND
EXCLUSIVE TO STEEL HORIZONS
RELEASE # 1479
Within the past few months the mighty XB-48 has been added to the U. S. Air Force’s arsenal of fighting aircraft. The XB-48, built by The Glenn L. Martin Company, Baltimore, Maryland, is the world’s largest high-speed jet-bomber of conventional exterior design — though in some respects it remains highly unconventional.
Rated a lightweight among Air Force bombers, the XB-48 is powered by six General Electric J-35 gas turbine engines capable of delivering a total of 24,000 pounds of thrust. This power potential, when converted into more familiar horsepower, would about equal the combined energy of 290 average passenger automobiles.
With information on its performance characteristics still largely under wraps due to military security regulations, the Air Force has admitted that the XB-48 flies in the "500 mile per hour" class. Because of its speed, which is great, indeed, for a bomber, an entirely new development in landing gear was designed — a tandem type, in which the main wheels like those of a bicycle are located one behind the other.
Tricycle landing gear, found on most aircraft today, was entirely impractical for the XB-48, for with tricycle gear, the main wheels fold into wing wells after the craft becomes airborne. With the XB-48, there is not sufficient room in the wings for large wheel wells because the wings are designed for high speeds and had to be extremely thin. By arranging for the tandem gear to fold into the fuselage of the XB-48, the desired wing design became practical.
Obviously, some wing support is necessary when the new bomber is stationary on the ground. Hence, small wheels are located midway under each wing, and fold into the nacelles of the outboard engines when the craft is in flight.
Viewed directly from the front, there is a noticeable droop to the wings, particularly toward the tips. However, in a fast taxi run, the droop becomes reversed – to a degree where the outrigger wheels are lifted from the ground. From this point on, the XB-48 moves forward on its two "bicycle type" gear, and a strange sight it is, for at a distance the small wheels are not easily visible. In a fast run or actual take-off, with outriggers already off the ground, lateral stability is supplied by the lift of the wings.
So complete a departure from conventional landing gear types required a great deal of advanced planning and testing. Early in design stages, a Martin B-26 Marauder was secured from the Air Force and fitted up with tandem main wheels and outrigger balance wheels. Then dozens of landing and take-off tests were made. Movies and pilot reports were studied thoroughly before the decision was made that the new gear would function in a completely satisfactory manner on the XB-48.
Because of high temperatures necessarily present in the operation of a modern jet aircraft like the XB-48, certain parts had to be designed to withstand unusual heat. Therefore, stainless steel was used for vital components of the jet engines; for anti-icing ducting; for a number of flexible connections, and in other installations where metals must give high performance while being subjected to temperatures of 800° F. and more.
The XB-48 packs a lethal punch — more than 10 tons of bombs, over a combat radius of hundreds of miles, and when necessary it can take its load to 40,000 feet where danger from flak is greatly diminished.
In building the first in the unprecedented time of thirteen months, the Martin Company developed a streamlined production technique which won high praise in the industry and from the Air Force’s top command.
The engineering staff, which at its peak numbered 137, moved right into the plant, adjacent to the shop. A separate accounting section was established, its files and desks almost touching the engineers' drawing boards. Blueprints were made on the spot in "while-you-wait" style and materials ordered at the same time the designs were being drawn.
The XB-48 mock-up was only a few steps away, making possible instant checking of changes of placement of parts. The plane itself was built in the same section of a huge assembly building, a few hundred feet from the project offices. To add even more speed, a separate raw stores was established, stocking only raw materials and parts need on the XB-48.
This streamlined, simplified system boiled the entire project down to its essentials — kept each part moving at maximum speed and efficiency toward its proper place in the finished airplane.
An engineer would sketch a simple plan for a special part. Instead of sending it through channels, he'd walk a few feet to the shop, lean over a machine and discuss it with the man who would make the part.
If no tooling were necessary, work on the part would begin immediately. If a tool were required, both men would walk over to a tool designer, explain their problem, and the three of them would work out the necessary tool. Then tool and drawing would be taken to the shop for manufacture. Then the part was ready, it would be taken immediately to the airplane, where the man who designed it and the man who made it could watch it installed. All of which adds up to one of the most unorthodox airplane production programs ever attempted — and, also, one of the most successful.
Two of these great new bombers have been delivered to the Air Force and are now undergoing advanced testing at Wright-Patterson Field, Ohio. The second is expected to show even more advanced performance then the first.
They have a gross weight of 102,600 pounds; an empty weight of 58,500 pounds; wing area of 1,300 square feet; span of 108'4"; length of 85'9"; and height of 27'6". Crew is 3 men.
National Archives II, College Park, MD
Record Group 342: Records of U.S. Air Force Commands, Activities, and Organizations, 1900 – 2003
Series: Central Decimal Correspondence Files, 1919 – 1950
HMS/MLR Entry Number: P 26
Declassified via NND 917647
Also filed in XB-51
AFMRD/Col Sessums/slb/71385
14 Feb. 49. Rewritten from attached
copies prepared by Capt. Strathy
MEMORANDUM FOR THE UNDER SECRETARY OF THE AIR FORCE
SUBJECT: Consideration of Various Martin Company Aircraft
1. Martin AM-1: Air Force interest in the ground support fighter has recently been revived and characteristics are at present being prepared as a result of a meeting of all interested agencies. At the present time there are two aircraft in production which may meet the requirement for the ground support fighter. These are the Martin AM-1 and the Douglas AD-2. A letter was prepared this date to the Chief of Naval Operations requesting two each of the latest Martin AM series and latest Douglas AD series be made available to the Air Force for evaluation at the Air Force Proving Ground, Eglin Air Force Base, Florida, as possible support fighters. From discussion with Naval officers, it appears that of the two, the Douglas AD-2 will prove to be the more suitable of the Navy attack type aircraft, but in order to show no favoritism, a full evaluation should be run at the Air Proving Ground.
2. XB-51 Light Bombardment Airplane: This plane represents Air Force exploration in the jet ground support field. It is presently approximately 30% complete, the first flight being scheduled for October, 1949. The value of a jet airplane for ground support purposes is still very debatable. General opinion seems to favor flexibility which can be obtained by using a turbo-prop type ground support aircraft. Production orders for this airplane should definitely not be considered pending flight tests and full evaluation of the aircraft against tactical requirements.
3. Martin Model 247-1 (XB-48 Equipped with Four (4) T-40 Turbo-Prop Engines): The above Martin proposal parallels a similar one submitted by North American Aviation Company wherein only two (2) T-40 turbo-prop engines are installed on the B-45C. It would be most uneconomical to procure production tooling and the Martin airplanes using four (4) T-40 engines when aircraft presently in production equipped with only two (2) of these engines can produce similar or superior performance to that proposed by Martin. Present funding limitations indicate that the Air Force cannot finance another production order in this category and that at the present time current plans for the B-54 and B-47 aircraft adequately meets the Air Force's needs.
D. L. PUTT
COPY COPY
Record Group 342: Records of U.S. Air Force Commands, Activities, and Organizations, 1900 – 2003
Series: Central Decimal Correspondence Files, 1919 – 1950
HMS/MLR Entry Number: P 26
Declassified via NND 917647
Also filed in XB-51
AFMRD/Col Sessums/slb/71385
14 Feb. 49. Rewritten from attached
copies prepared by Capt. Strathy
MEMORANDUM FOR THE UNDER SECRETARY OF THE AIR FORCE
SUBJECT: Consideration of Various Martin Company Aircraft
1. Martin AM-1: Air Force interest in the ground support fighter has recently been revived and characteristics are at present being prepared as a result of a meeting of all interested agencies. At the present time there are two aircraft in production which may meet the requirement for the ground support fighter. These are the Martin AM-1 and the Douglas AD-2. A letter was prepared this date to the Chief of Naval Operations requesting two each of the latest Martin AM series and latest Douglas AD series be made available to the Air Force for evaluation at the Air Force Proving Ground, Eglin Air Force Base, Florida, as possible support fighters. From discussion with Naval officers, it appears that of the two, the Douglas AD-2 will prove to be the more suitable of the Navy attack type aircraft, but in order to show no favoritism, a full evaluation should be run at the Air Proving Ground.
2. XB-51 Light Bombardment Airplane: This plane represents Air Force exploration in the jet ground support field. It is presently approximately 30% complete, the first flight being scheduled for October, 1949. The value of a jet airplane for ground support purposes is still very debatable. General opinion seems to favor flexibility which can be obtained by using a turbo-prop type ground support aircraft. Production orders for this airplane should definitely not be considered pending flight tests and full evaluation of the aircraft against tactical requirements.
3. Martin Model 247-1 (XB-48 Equipped with Four (4) T-40 Turbo-Prop Engines): The above Martin proposal parallels a similar one submitted by North American Aviation Company wherein only two (2) T-40 turbo-prop engines are installed on the B-45C. It would be most uneconomical to procure production tooling and the Martin airplanes using four (4) T-40 engines when aircraft presently in production equipped with only two (2) of these engines can produce similar or superior performance to that proposed by Martin. Present funding limitations indicate that the Air Force cannot finance another production order in this category and that at the present time current plans for the B-54 and B-47 aircraft adequately meets the Air Force's needs.
D. L. PUTT
COPY COPY