Monday, December 19, 2011


B-47 Stratojet


B-47 Stratojet

The B-47 was the first American all jet bomber.  German wartime research contributed to the swept wing design of both the F-86 Sabre and this medium range bomber.  It was truly a revolutionary aircraft when first flown in December, 1947 and its experience would heavily influence the design of the legendary B-52 introduced a few short years later.  

B - 47E

Crew:                    3 - Pilot, copilot, navigator-bombardier

Power:                  6 - General Electric 3269 kg / 7200 lb thrust J47-GE-25 turbojets

Max. Speed:         975 kph / 606 mph
Ceiling:                 12,352 m / 40,500 ft plus
Range:                  5794 km / 3600 miles
Climb:                  1326 m / 4350 ft per minute at maximum power

Weight -
Empty:                 36,663 kg / 80,756 lb
Max. Take Off:    89,973 kg / 198,180 lb

Size -
Wingspan:           35.36 m / 116 ft
Wing Area:         132.66 sq m / 1428 sq ft
Length:                33.48 m / 109 ft 10 in
Height:                8.51 m / 27 ft 11 in

                          2 - 20 mm / 0.78 in cannon in remote controlled tail turret
                               9080 kg / 20,000 lb max. bomb load




The B-47 had limited internal fuel capacity and was not a true intercontinental bomber without IFR (In Flight Refueling).  This capability was added to the B-47B model along with two 1500 gallon drop tanks attached to the wings.  Each wing of 45 bombers was expected to also have 20 KC-135 tankers to extend its range.  The KC-135s had incompatible piston engines making air refueling difficult for the born for speed Stratojet.  

1,500 B-47s deployed in 1956

The Strategic Air Command had 28 B-47 wings by the mid-1950s, not including the over 200 Stratojets used for reconnaissance missions.  The first B-52s began supplanting this force after 1955.  By 1960 the Air Force was phasing out the remaining B-47s with the new B-58 Hustler but numerous other factors including ICBMs and Polaris submarines made the medium range B-47 an expendable weapons system.  

Labeled Diagram

The 35 degree swept back wing was too thin to house landing gear which led to the bicycle arrangement along the center line of the fuselage.  Landings required concentration and could be particularly treacherous in a crosswind.  The B-47 was a demanding aircraft to fly and left pilots worn out after long flights.  

 Copilot Instrument Panel

The B-47 was a challenging plane to fly and tandem seating meant the two pilots could not see what the other was doing thus making crew coordination, rigorous checklist communication, all the more critical.  The large Plexiglas clamshell canopy provided an excellent view but made daylight flying extremely hot unless the navigator, buried in the nose, was left to freeze from air conditioning.  Little thought was given to crew comfort but as an aircraft it had the reputation for handling like a fighter. 

Tail Drag Chute

There were two chutes deployed on landing, an approach chute as seen above and a brake chute once landed.  This landing photo is from Lincoln Air Force Base Museum.

Rocket Assisted Take Off

Engines of the early jet age lacked power output and several were required.  Take offs with heavy payload were assisted by the additional boost of 18 solid fueled rockets located aft of the bomb bay.  Rocket assisted take off and parachute deceleration enabled B-47s to be more diversely stationed at air bases with shorter runways.  The image is at John Weeks.

Eielson AFB, Alaska

Range was the primary limitation of the B-47 and many were based in England, Spain, North Africa and Alaska in order to be in striking distance of the Soviet Union.  

B-47 with claimed fighter performance

For the first couple of years following its introduction the B-47 could fly faster and higher than contemporary fighters.  It had an agility in handling unexpected for a bomber.  Its qualities made it the choice for highly dangerous reconnaissance missions into Soviet airspace prior to the U-2 during the early years of the Cold War.  



1 comment:

  1. The B-47 was not the first American "all jet" bomber. Think B45 Tornado, B43?