Consolidated Vultee B-32 In Last-Round Action

Design and construction details at AAF's newest superbomber are revealed as craft flies against Japs. Featured are extremely high wing loading and auto-synchronized reversible pitch propellers.

Adding its might to the greatest display of air power ever achieved, Consolidated Vultee's B-32 four-engine superbomber was reported in action before Jap capitulation, permitting revelation of some of its design and construction details.

A high-wing monoplane of 135-ft span, the B-32 is powered by four 2,200-hp. Wright engines turning four-blade Curtiss Electric reversible pitch propellers of 16 ft 8 in dia. The reversible pitch propellers make it possible to reduce landing runs by about one third, a fact expected to permit use of smaller fields than would ordinarily be possible for a plane of this size. just as important, however, is the fact that wear and tear on brakes and tires is materially reduced, thereby cutting down on maintenance and overhaul.

Wing of the B-32 employs a modified Davis foil somewhat like that utilized on Convair's B-24 Liberator, the outer panels especially being quite similar. Following conventional practice, the wing is built up of two spars, metal ribs, and stressed skin. Flush riveting is used throughout the wing.

Fowler type metal flaps, having a maximum deflection of 40°, add approximately 30 percent to wing area when in full extended position. Flaps are built in two sections, the inboard section extending out from the fuselage to between engines, the outer section from there to the ailerons. Both sections travel on three tracks and are extended and retracted by hydraulically-operated cables. Aft tips of the engine nacelles, which extend some 2 ft beyond the trailing edge, extend with the flaps.

The Convair-NACA thermal anti-icing system, first developed for PBY and B-24 types (see Aviation's Sketchbook of Design Detail, Oct 1943), is built into the B-32. Under extreme conditions this system will use 1,500,000 Btu per hr, or enough to heat 25 five-room houses an hour.

Certain sections of the B-32 wing are covered with very heavy gauge dural which serves as armor plating for vital spots. Since the chord of the Davis foil is not as great as that of other wing types, and the gross weight of the B-32 runs up to 120,000 lb, wing loading is believed to be more than 80 lb/diagonal ft, at or near the highest loading yet achieved.

Ailerons are of monospar metal construction, fabric covered. Balanced both statically and dynamically, they require no boost system. Trim tabs are electrically operated from toggle switches in the pilots' cockpit, the actuating motors being located at the tabs.

To facilitate maintenance, all engine nacelles are interchangeable and complete power egg changes can be accomplished in 2 hr. This is made possible by a monocoque nacelle structure which attaches to the wing by five bolts. Normal servicing is also facilitated by the nacelle design through such features, for example, as a large door in the upper surface through which a mechanic may enter the accessory compartment to make adjustments.

Air ducts for oil radiators, intercoolers, and superchargers — two for each engine — are built into nacelles below the engine. Since each engine is equipped with two superchargers, the craft's service ceiling is believed to be well over 30,000 ft. Cowl flaps are electrically operated and jet type exhaust stacks are used, the latter adding 7 to 8 mph to top speed at altitude.

As is the case in the wing, certain sections of the engine nacelle are built of heavy dural to reduce flak and enemy-fire damage.

Engines of the B-32 are synchronized by the Curtiss automatic synchronizer (see Sept 1943 Aviation), which eliminates necessity for constant changing of throttle settings. B-32 is the first craft on which the synchronizer has been a production item.

Main wheels of the tricycle landing gear retract hydraulically up and forward into wells in the inboard nacelles in about 10 sec, with universal-connected tie rods pulling fairing doors closed to completely cover them in retracted position. Main gear uses dual 56-in tires, and two brake systems are provided — normal hydraulic and emergency hydraulic.

Nose gear is a co-rotating Convair-developed type with dual 39-in wheels splined to a common axle, with the axle turning on two bearings in the oleo knuckle. This design prevents shimmy without requiring use of shimmy damper and torque links.

Landing gear can be lowered by any of three systems: Normal hydraulic, emergency motor-driven hydraulic system, or by a hand pump.

Fuselage is 83 ft 1 in long with a circular cross section having a maximum dia of 9 ft 6 in. Approximately 1,000 lb in weight was saved by the use of artificially-aged aluminum. Flush riveting is used on the fore part of the fuselage, conventional brazier-head rivets being employed aft of the pilots' compartment.

Quarters for bombardier, pilots, aerial engineer, avigator, and radio operator are all forward of the leading edge of the wing, and another cabin aft of the dual tandem bomb bays is provided for other crew members. In both cabins, Convair-developed lightweight glass fiber soundproofing is installed.

Bomb bay doors are similar to those developed for the B-24 — aluminum alloy sheet backed by hat-shaped stiffeners rolling up alongside the fuselage on tracks by means of hydraulic jacks. A heavy built-up beam running the full length of the bottom of the bay also serves as a catwalk between cabins.

The full cantilever stabilizer, built as a complete unit, is attached to the fuselage by bolts attaching to built-up channel section formers inside the fuselage. Metal fabric-covered elevators follow conventional construction and have combination trim and servo tabs which are cable operated.

The single vertical fin is of unusual height — its top is 32 ft 2 in above the ground when the plane is in taxi position — giving such stability that it is reported the craft can be kept on course with minimum difficulty even with both engines out on one side. The fabric-covered rudder is mounted on three hinges and has trim and servo tabs.

Armament details may not be re- leased, but it may be assumed that the B-32 is at least as well armed as other American bombers, which would mean a minimum of at least ten 50-cal machine guns. It is understood that no central fire control system is employed.

Production is now concentrated at Convair's Fort Worth, TX, division, with the contract scheduled for completion around the end of this year. Here much the same production system employed for B-24s is being utilized; in fact many of the work stands used on the moving final assembly line have been re-employed with only slight modifications to take care of the difference in size of the two planes. And, as is becoming the rule in American aircraft production, combat-dictated modifications are being made right on the production line.

Nuclei of the flight crews were given streamlined transition training by the AAF Technical Training Command, headed by Lt Gen Barton K Yount, at the Fort Worth Army Air Base, on the opposite side of the field from the Convair plant. Here the Air Commander (new name for the pilot), Pilot (new name for co-pilot), and Aerial Engineer (who used to be called flight engineer) were welded into a team during the 80 hr of flying time given at this base. Since the pilots all average about 1,000 hr of four-engine bomber time before reaching the base, this apparently low time was found sufficient to train them on the new craft.

Upon completion of the flying and ground school transition work, the crew nucleus then proceeded to an advanced training base, where the remaining five men of the crew were brought together for final training.

This article was originally published in the September, 1945, issue of Aviation magazine, vol 44, no 9, pp 168-169.
The original article includes 3 photos.
Photos are not credited.