Within the Manhattan Project was a sizable scientific and technical effort to determine the progress of the Nazi atomic bomb program. One of the key scientists in this effort was future Nobel Laureate Luis W. Alvarez who in 1944 was working at Los Alamos in New Mexico when he was asked by General Leslie Groves, the head of the Manhattan Project, if there were a way to detect from the air if the Germans were operating plutonium-fueled reactors. Given only a week by Groves, Alvarez proposed an airborne collection system to detect Xenon-133, a by-production of reactor fission with a five-day half life which had distinctive patterns of gamma and beta radiation making it an ideal marker for German reactor activity.

General Groves' idea was to determine the locations of potential German reactors and then disrupt their atomic bomb effort via airstrikes.

With the help of General Electric, Alvarez designed an activated charcoal-based filter system that would fit in the nose compartment of a Douglas A-26 Invader that would fly several hundred feet above the ground. In the fall of 1944, three A-26s carrying Alvarez's Xenon-133 detector scoured three possible areas where intelligence analysts thought a German reactor might be operating. Fast and agile enough to evade AAA-gunfire but large enough to carry the bulky detector, no Xenon-133 was ever found.

Source: Spying on the Bomb- American Nuclear Intelligence from Nazi Germany to Iran and North Korea by Jeffrey T. Richelson. W.W. Norton, 2007, p40-41, 49-50.

Dr. Forrest Bird, head of a biomedical engineering corporation based in Palm Springs, bought a Consolidated PBY Catalina (specifically it was a Canadian-built PBY-5 Canso) that in 1968 he had modified into a four-engined configuration called the Bird Innovator. Outboard of the existing radial engines were added nacelles accommodating 360-horsepower Lycoming piston engines driving Hartzell three bladed propellers. Though the speed increase from the Lycomings was modest, the real improvement came from the propwash of the new additonal engines which, in effect, acted to energize the airflow across the outer wings of the Catalina which were notorius for being sluggish particularly in engine out situations.

The Bird Innovator also had strengthened wings and a taller fin and rudder as well. The engineer's controls were also moved to the cockpit to allow the aircraft to be operated by a single pilot. After passing through various owners, the aircraft in 1997 was returned back to its original layout.

Source: General Dynamics Aircraft and their Predecessors by John Wegg. Putnam Aeronautical Books/Naval Institute Press, 1990, p78.

On 11 July 1951 the USAF selected Beechcraft to design and build a new high-performance twin-engine transport-trainer aircraft to replace the Beech C-45s then operated by the Air Training Command. The new aircraft was designated the T-36A and would have been powered by two 18-cylinder 2300-horsepower Pratt & Whitney R-2800 radial engines driving three-bladed propellers for a cruising speed over 300 mph. In the training role, the T-36A would have carried three students and an instructor or as a light transport, it would have carried 12 passengers and a crew of 2.

By November 1951 the Air Force Inspection Board reviewed the full-scale mockup at Beech's facilities in Wichita. By that summer Beech began construction of a new production facility at Beech Field for T-36A production. In January 1953 the final details were fixed and production planned to start for the first batch of 195 aircraft for the USAF with Canadair in Montreal as the main subcontractor.

On 10 June 1953 with the maiden flight of the prototype only an hours away the Department of Defense canceled the T-36A contract and ordered all development activities to cease. Two aircraft were complete, the prototype that was being readied for its maiden flight and a complete static test airframe. Both airframes were scrapped on site in major blow to Beechcraft.

Source: Beech Aircraft and their Predecessors by A.J. Pelletier. Putnam Aeronautical Books/Naval Institute Press, 1995, p111.

First flying on 27 May 1970, the Boeing Vertol 347 testbed was a modified CH-47A Chinook (aircraft 65-07992) used for Boeing's HLH (Heavy Lift Helicopter) program. The helicopter featured just over 9 foot extension of the forward fuselage cabin, a raised aft rotor pylon, four bladed rotors that were two feet longer than a standard Chinook blade, fly-by-wire controls and retractable landing gear.

But the most unique feature of the Model 347 was a variable-incidence wing that created extra lift to offload the main rotors. There was also a retractable gondola in the forward fuselage that had a full set of flying controls during flying crane operations. As the twin rotors no longer overlapped, some degree of noise reduction was also achieved. The Model 347's performance was greater than that of the standard Chinook, but flight testing ended in 1975 with the cancellation of the HLH program.

The BV-347 is currently on outdoor static display at the US Army Aviation Museum with sixty other aircraft at Fort Rucker, Alabama.
Source: Air International, October 2009. "Fort Rucker- Home of Army Aviation" by Kees van der Mark and Arnaud Boxman, p80.

One of the unique features of the Mikoyan MiG-23/27 Flogger fighter aircraft is that compressed air for the pneumatic systems is stored inside the main undercarriage legs and axles. The main pneumatic system fed off a 12.1 liter "bottle" inside the right undercarriage leg to operate the cabin pressurization, canopy operation, moving the sliding panels that cover the gaps on the variable-geometry wings, the main wheel brakes, main fuel valve, braking parachute deployment, activating the emergency drive for hydraulic system and closing the air vents in the avionics bays. A smaller 1.75 liter "bottle" inside the right wheel axle supplied compressed air to the radar bay and avionics heat exchanger which used fuel as coolant.

A 12.1 liter "bottle" in the left main undercarriage leg supplied compressed air for emergency lowering of the landing gear, folding of the ventral fin and operation of the brakes. A smaller 1.75 liter "bottle" in the left wheel axle supplemented the emergency systems on the Flogger. The main valve to fill the compressed air circuits in both main landing gears was located in the left main wheel well.

Source: MiG-23/27 Flogger- Soviet Swing Wing Fighter/Strike Aircraft by Yefim Gordon and Keith Dexter. Midland Publishing/Aerofax, 2005, p52.

The most numerous aircraft in the US Army's fixed-wing aircraft fleet is the Hawker Beechcraft King Air which is used in over 165 aircraft over 13 different version from utility transport (such as the C-12 Huron) to special mission aircraft (like the RC-12 Guardrail). By mid-2009 the utilization of this diverse fleet of King Air variants had already reached approximately 173,000 flight hours.

Approximately 113 C-12s are in use operationally and fly an average of 48.2 hours monthly with an operational readiness rate of 91.1%. The more complex RC-12s fly 38.6 hours monthly and have an average readiness rate of 89.9%. Both fleets of aircraft have an average age just over 20 years old.

The Army's first King Air was delivered on 16 May 1967 in the form of the U-21A Ute that was an unpressurized hybrid of the Beech Queen Air fuselage with the wings and tail of the newer King Air 90 series. The newer C-12A based on the Super King Air 200 was first deployed by the Army in July 1975. The newest Army King Airs are modified C-12C/D/V aircraft for Task Force ODIN (TF ODIN- Observe, Detect, Identify, and Neutralize) created at Fort Hood, Texas in August 2006 to conduct airborne intelligence and surveillance in support of anti-IED efforts in Iraq. The TF ODIN aircraft have an underfuselage Lynx hi-resolution SAR, EO/IR sensor turrets and other communications/sensor equipment to assist in the counter-insurgency efforts.

Source: Air Forces Monthly, November 2009. "US Army King Airs" by Tom Kaminski, p84-89.

In 1957 the last of the Auster liason aircraft were retired from the Royal Air Force with great reluctance. The British Army, however, keen to replace the unique capabilities of the Auster with the de Havilland Beaver, came up against a government limit on the size of aircraft the Army Air Corps could operate- 4000 lbs. Anything larger was to be operated by the RAF. However, the AAC wasn't deterred by this regulation and managed to get a waiver to allow them to order 46 DHC-2 Beavers delivered from 1960-1967. No other type of aircraft was even considered.

However, as early as 1952 de Havilland Canada was considering a British-built Beaver. The 550 horsepower Alvis Leonides radial, already in use with the Percival Provost and Percival Pembroke twin engine communications aircraft, offered 100 more horsepower for an additional weight of 98 lbs. One of the engines was shipped to de Havilland's plant in Downsview (Toronto) for testing on a Beaver. Aircraft CF-GOE-X was fitted with a longer nose cowling to accommodate the Leonides engine which drove a larger three-bladed propeller. The vertical fin required redesign with a taller design with straight leading and trailing edges and more dorsal fin fillet area.

The Leonides Beaver (also known as the Beaver Mk.2) first flew at Downsview on 10 March 1953 and demonstrated improvements in top speeds and time-to-climb. However, the cost of the conversion outweighed the additional performance and the British Army Air Corps ended up ordering standard Wasp Junior-powered Beavers. During flight testing in Britain, the AAC even landed one of their Beavers on a Royal Navy carrier deck.

Source: The Immortal Beaver- The World's Greatest Bush Plane by Sean Rossiter. Douglas & McIntyre, 1996, p104-106

During the development of the Boeing 757, once it was decided that both the 757 and 767 flight decks were to be common, the original design for the 757's cockpit that was based on the 727 now faced the challenge of having to fit the widebody cockpit of the 767 onto the single-aisle design of the 757. In a rare move for Boeing, the design of the 757's nose was reconfigured after program launch in an effort to achieve a common rating for both aircraft.

Using the same forward windshield, related structures and cab geometry as the 767, the design was then altered to suit the narrower fuselage of the Boeing 757 with the goal of having the same visual and ergonomic geometry for the flight crew as that of the larger 767. The 757's nose section curves upward more dramatically than past Boeing jets as the point of nose is actually below the fuselage centerline with the flight deck floor a step down from the main deck.

The result was a cockpit with more visibility than past Boeing designs and aerodynamic noise also improved, with a 6 dB drop over the aerodynamic noise of the 727. The wider cockpit improved storage space with more room as well as improved air conditioning circulation patterns and the by providing a wider space at the front of the aircraft, there was more space for the forward lavatory and galley.

The extensive changes to the 757's nose and cockpit were all driven by the need for a common type rating for both aircraft and as the 767's cockpit had been designed first, it was adopted for the 757 with modifications. But with an identical windshield and instrument panel, much of the associated structure was also nearly identical in many ways.

Source: Boeing 757 and 767 (Crowood Aviation Series) by Thomas Becher. The Crowood Press, 1999, p33-35.

In August 1948 the US Navy's Bureau of Aeronautics sent out a request for proposals (RFP) for a carrier-based long range heavy attack aircraft ("Class VA") as part of Outline Specification 111 (OS-111). The primary mission of the Class VA design was the high altitude delivery of a nuclear weapon no less than 1,700 nm from the carrier which at the time was to be the CVA-58, the USS United States but it was also implied that operation of the design from smaller vessels like the Midway class would also be beneficial. The Navy would get 8 proposals from 7 manufacturers.

Uniquely among the companies that submitted proposals for the Class VA competition, Douglas Aircraft submitted two proposals from two different teams- one from the Santa Monica Division and one from the El Segundo Division. The El Segundo Division's design was designated the Model 593 and rather unusually featured a tail dragger layout for an advanced twin jet design. The rationale for what seemed like an archaic landing gear layout was that on USS United States, the lowered tail meant that the Model 593 could be stowed in the hangar deck without folding the vertical fin. On the Midway class, only a portion of the vertical fin would have to folded instead of the entire fin. The tailwheel layout also offered ease of handing on the carrier elevators as well.

Throughout the Model 593's design process, emphasis was placed uniquely amongst the Class VA submissions to allow operations from as many types of aircraft carriers as possible from the supercarrier USS United States to the Midway class and even the smaller Essex class carriers. The twin jet design that resulted offered more flexibility and as a smaller design was lower in cost.

In March 1949 the Douglas El Segundo design and the Curtiss-Wright proposal were selected for further development. The following month, however, the USS United States was cancelled and the Navy instructed BuAer to modify the Class VA project for operation from the Midway class. As the Midway class vessels were smaller, this gave the lighter and smaller Douglas El Segundo Model 593 a strong advantage over the Curtiss-Wright design. By July of 1949 the Douglas Model 593 was selected as the winner by which point the design had been refined further and the tail dragger layout replaced with a tricycle undercarriage. The Model 593 would go into production as the A3D Skywarrior, vindicating the El Segundo team's gamble.

Source: Secret Aerospace Projects of the U.S. Navy: The Incredible Attack Aircraft of the USS United States, 1948-1949 by Jared A. Zichek. Schiffer Publishing, 2009, p9-10, 46-56, 207-211.

In the early 1950s as the McDonnell F2H Banshee was being deployed by the US Navy, one of its roles was that of a nuclear weapons delivery platform using a special pylon under the left engine. But the weight and asymmetry of a full fuel load and the nuclear bomb meant the Banshee couldn't be catapulted off the carriers of the day. The solution was for the Banshee to take off from the carrier with a light fuel load and once at higher speeds and altitudes, the safety margin increased for such an asymmetric load.

Air refueling was settled upon as the solution to the problem, with special refueling packages being developed for the North American AJ Savage bomber to carry in the bomb bay- the booster jet engine was removed from the lower aft fuselage and the refueling hose and drogue passed through what was the jetpipe. On the Banshee, a refueling probe replaced one of the 20mm cannons in the nose so the aircraft could top off its tanks from a Savage tanker after takeoff. By the end of 1953 AJ Savage tankers were deployed with Banshee squadrons giving the Navy its first jet nuclear strike capability.

It became immediately obvious to the Navy that air refueling could increase safety margins during carrier operations as before, jets could only land with enough fuel for a few attempts at landing before having to divert to a land airfield, or worse, ditch, due to maximum landing weight restrictions. Having a tanker in the carrier pattern allowed aircraft to make multiple attempts at carrier landings. By 1955 the US Navy ordered all carrier based aircraft to be capable of inflight refueling.

Not long after Douglas developed the buddy store which contained not only additional fuel but the refueling hose and drogue in a self-contained package that could be attached to any compatible aircraft in the carrier air wing from the venerable AD Skyraider to the latest tactical jets. In 1957 the first AD-6 Skyraider tanker became operational with the Navy- with the buddy store in the centerline and two wing tanks, the Skyraider tanker could remain airborne during a complete carrier landing cycle to refuel any aircraft that needed additional fuel to make another carrier landing attempt.

Designer Ed Heinemann of Douglas stated that keeping two Navy jets from ditching during carrier landing cycles "roughly paid for the development costs for the entire buddy store program."

Source: US Naval Air Superiority: Development of Shipborne Jet Fighters 1943-1962 by Tommy H. Thomason. Specialty Press, 2007, 196-199.