Mission

The KB-29P aircraft’s primary purpose was to perform in-flight refueling of other planes using the flying boom method. It differed from the standard B-29 plane by eliminating all defensive armament and installing specialized in-flight refueling equipment.

Dimensions and Weights

DIMENSIONS	Imperial	Metric
Wing
Span	141.2 ft	43 m
Incidence	4°	4°
Dihedral	4°29'23"	4°29'23"
Sweepback(LE)	7°1'26"	7°1'26"
Wing Area	1720 ft2	159.8 m2
Aspect Ratio	11.5	11.5
Wing Section	Boeing 117	Boeing 117
M.A.C.	154.41	47.1 m
Length	120.1 ft	36.6 m
Height	27.8 ft	8.5 m
Tread	28.5 ft	8.7 m
Prop. Grd Clearance	1.3 ft	0.4 m
WEIGHTS
Loading
Empty	69,011 lbs (E)	31.303 kg
Basic	70,645 lbs (A)	32.044 kg
Operating	74,705 lbs	33.886 kg
Design	135,000 lbs	61.235 kg
Combat (*)	84,665 lbs	38.403 kg
Max Take Off (1)	138,500 lbs	62.823 kg
Max Landing (2)	135,000 lbs	61.235 kg

(E) Estimated
(A) Actual
(*) For basic mission
(1) Limited by performance
(2) Limited by gear strength

Engines

Attribute	Value
POWER PLANT
No, & Model	(4) R-3350-57 or-57A
Manufacturer	Curtiss - Wright Corp., Wright Aeronautical Corp. Division
Engine Spec	95-28266-5
Turbo	(2) B-31
Turbo Manufacturer	General Electric Co.
Red, Gear Ratio	0.35
PROPELLER
Propeller Manufacturer	Curtiss - Wright Corp.
Blade Design No.	1016-4C4-18
Propeller Type	CS, FF, Reverse,
No. Blades	4
Propeller Diameter	16' 8" (5.1 m)
ENGINE RATINGS
Take Off	2200bhp/2800rpm
Military	2200bhp/2600rpm/2500ft
Normal	2000bhp/2400rpm/4000ft

Electronics

Equipment	US Designation
VHF Command	AN/ARC-3
Command	SCR-274N
Interphone	AN/AIC-2
Liaison	AN/ARC-8
Radio Compass	AN/ARN-7
Marker Beacon	RC-193A
Radar	AN/APQ-13A
Loran	AN/APN-9
IFF	SCR-695B
Rendezvous Radar	AN/APN-2B,AN/APN-68 and AN/APN-11

Crew

The KB-29P had a new crew member in the form of a boom operator who was responsible for operating the boom and connecting it to a receiver aircraft receptacle. This crew member sat in the converted tail turret position of the B-29.

The crew list for the KB-29P was:

1. Pilot
2. Co-pilot
3. Navigator
4. Flight Engineer – Pumping system operator
5. Radio operator
6. Radar operator
7. Flying Boom operator

Fuel

The KB-29P included form-fitting bomb bay tanks, each of which was jettisonable. All fuel tanks in the KB-29P tanker were made up of nylon non-self-sealing cells. The aircraft had a maximum fuel capacity of 11,954 gallons, which was greater than that of the B-29 bomber, which was 9,363 gallons.

Initially, all fuel tanks were serviced with Mil-F-5572 aviation gasoline, which was available in two grades – 100/130 or 115/145. However, when the KB-29Ps were later used to refuel jet aircraft, the fuel servicing strategy was changed. The four main wing tanks and the two bomb bay tanks were restricted to the use of aviation gasoline, while the wing center section tanks were serviced with JP-4 jet fuel.

Location	No. Tanks	Gal	Liters
Wing, outbound *	2	2800	10.599
Wing, inbound *	2	3000	11.356
Wing, center	1	1400	5300
Bomb bay, forward*	1	2573	9740
Bomb bay, afterward*	1	2181	8256
	Total	11,954	45.251

(*) nylon non-self-sealing cells

Refueling Equipment

A maneuverable telescoping boom with an articulated nozzle is attached to the bottom of the fuselage near the tail, serving as a connection and medium for fuel transfer between the tanker and receiver aircraft. The boom operator’s compartment (formerly the tail gunner’s compartment) houses hydraulic and aerodynamic controls for the boom.

The fuel system comprises a manifold system for normal operations and a high-capacity pump system for refueling. With the exception of the hydraulically-operated brakes and boom, all equipment is operated electrically.

The list of refueling equipment is the following:

• Telescopic Flying Boom
• Articulated Boom Nozzle
• Ruddevators for aerodynamic control
• Signal Amplifier
• Radar equipment necessary for rendezvous with receiver:
  • AN/APN-2B
  • AN/APN-68
  • AN/APN-11

Refueling Operation process:

The KB-29P’s refueling operations were carried out with precision, requiring coordinated crew activities and careful formation flying.

1. The KB-29P aircraft would assume a cruising altitude, extending the boom, and positioning the receiver aircraft below and behind the tanker.
2. The boom operator would then guide the boom into the receptacle via ruddevator flight surfaces, which the boom operator manipulates using a conventional control stick. Contact is detected by a signal amplifier that controls equipment based on aircraft positions, rate of position change, and refueling line fuel pressure.
3. Then, the flight engineer and boom operator would work together to transfer fuel into the receiver aircraft. The tanker is equipped to supply fuel to the receiver plane at a selectively controlled rate, up to 600 gallons per minute.
4. During the fuel transfer, the receiver pilot would use the indicator lights, which displayed RIGHT, LEFT, UP, DOWN, FORWARD, and AFT, to make minor attitude adjustments and maintain position. As the weights of the two aircraft changed, and the center of gravity shifted, these adjustments became necessary.
5. If any predetermined limits are exceeded, an involuntary disconnect is automatically triggered. A voluntary disconnect may also occur, initiated either by the boom operator or receiver pilot, resulting in a fuel shut-off and boom disconnect.
6. Once refueling was complete, the receiver aircraft would drop off the boom. The boom operator would purge the refueling manifold with nitrogen to prevent any trapped fuel from causing an explosion.

Performance

The basic performance of the KB-29P was the following:

Loading and Performance – Typical mission

Conditions	Basic Mission		High Alt Refuel		Ferry range
TAKE-OFF WEIGHT	138,500 lbs	62.823 kg	138,500 lbs	62.823 kg	138,500 lbs	62.823 kg
Fuel at 6. 0 lb/gal (grade 100/130)	28,795 lbs	13.061 kg	35,271 lbs	15.999 kg	63,795 lbs	28.937 kg
Military load (transfer fuel)	35,000 lbs	15.876 kg	28,524 lbs	12.938 kg	None
Wing loading	80.5 lb/sq ft	393 kg/m2	80.5 lb/sq ft	393 kg/m2	80.5 lb/sq ft	393 kg/m2
Stall speed (power off, landing configuration)	103 kn	191 km/h	103 kn	191 km/h	103 kn	191 km/h
Take-off ground run at SL (1)	5,075 ft	1.547 m	5,075 ft	1.547 m	5,075 ft	1.547 m
Take-off to clear 50 ft (1)	7,570 ft	2.307 m	7,570 ft	2.307 m	7,570 ft	2.307 m
Rate of climb at SL (3)	500 fpm	152,4 m/min	500 fpm	152,4 m/min	fpm	152,4 m/min
Time: SL to 10,000 ft (3)	23. 8 min		23. 8 min		23. 8 min
Time: SL to 20, 000 ft (3)	61.8 min		61.8 min		61. 8 min
Service Ceiling (100 fpm) (3)	23,500 ft	7.163 m	23,500 ft	7.163 m	23,500 ft	7.163 m
Service Ceiling (one engine out)	19,000 ft	5.791 m	19,000 ft	5.791 m	19,000 ft	5.791 m
COMBAT RANGE (4)	1594 n.mi.	2952 km	1957 n.mi.	3624 km/h	4987 n.mi.	9236 km/h
Average speed	204 kn	378 km/h	204 kn	378 km/h	192 kn	356 km/h
Initial cruising altitude	10,000 ft	3.048 m	10,000 ft	3.048 m	10,000 ft	3.048 m
Final cruising altitude	10,000 ft	3.048 m	25,000 ft	7.620 m	10,000 ft	3.048 m
Total mission time	9.00 hrs		10.74 hrs		26.13 hrs
COMBAT RADIUS (4)	1000 n.mi.	1852 km	1154 n.mi	2137 km
Average speed	190 kn	352 km/h	211 kn	391 km/h
Initial cruising altitude	10,000 ft	3.048 m	10,000 ft	3.048 m
Refueling altitude	10,000 ft	3.048 m	25,000 ft	7.620 m
Refuel speed (6)	248 kn	459 km/h	311 kn	576 km/h
Final cruising altitude	10,000 ft	3.048 m	25,000 ft	7.620 m
Total mission time	11.71 hrs		12.08 hrs
COMBAT WEIGHT (5)	84,665 lbs	38.403 kg	86,120 lbs	39.063 kg	81,085 lbs	36.780 kg
Combat altitude	10,000 ft	3.048 m	25,000	7.620 m	10,000 ft	3.048 m
Combat speed (2)	288 kn	533 km/h	332 kn	615 km/h	290 kn	537 km/h
Combat climb (2)	2,025 fpm	617.2 m/min	1,735 fpm	529 m/min	2,160 fpm	658.3 m/min
Combat ceiling (500 fpm) (2)	39,500 ft	12.040 m	39,200 ft	11.948 m	40,450 ft	12.329 m
Service ceiling (100 fpm) (3)	42,900 ft	13.076 m	42,500 ft	12.954 m	43,800 ft	13.350 m
Service ceiling (one engine out) (3)	38,800 ft	11.826 m	38,450 ft	11.720 m	39,700 ft	12.101 m
Max rate of climb at SL (2)	2,135 fpm	650,7 m/min	2,080 fpm	634 m/min	2,275 fpm	693,4 m/min
Max speed at 30,000 ft (2)	349 kn	646 km/h	348 kn	644 km/h	350 kn	648 km/h
LANDING WEIGHT (5)	76,145 lbs	34.539 kg	76,469 lbs	34.686 kg	81,085 lbs	36.780 kg
Ground roll at SL	2,060 ft	628 m	2,075 ft	1.547 m	2,175 ft	663 m
Total from 50 ft	2,750 ft	838 m	2,760 ft	841 m	2,890 ft	881 m

(1)Take-off power
(2) Max power
(3) Normal power
(4) Detailed descriptions of RADIUS and RANGE missions are given on page 6.
(5) For Radius Mission if the radius is shown
(6) At normal rated power but not exceeding 250 MPH (EAS) as per T. O. AN 01-20EJAB-1 NOTES 1

Further reading

• Boeing B-29 Superfortress Specifications (1950)
• Boeing B-29A Superfortress Specifications (1950)
• Boeing B-29B Superfortress Specifications (1950)
• Boeing SB-29 Superfortress Specifications (1954)
• Tupolev Tu-4 Standard Specification & Performance
• Boeing B-29 Superfortress Facts: 11 things to know

Bibliography

• B-29 Superfortress in detail & scale, Part 2: Derivatives by Alwyn T. Lloyd
• KB-29P Superfortress SAC 8-MAR-1951, Air Materiel Command, U.S. Air Force