31 October 2009

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

30 October 2009

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.

29 October 2009

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.

28 October 2009

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.

27 October 2009

The Convair B-58 Hustler's tail cone that enclosed the tail gun was composed of tapered, concentric aluminum rings nested within each other and spring-loaded against each other to form a flexible aerodynamic shell for the gun system.

After looking at various options including rear-firing missiles and twin 30mm cannons, the General Electric T171 (first designation of the M61 Vulcan cannon) 20mm rotary cannon was selected in early 1954. The tail gun of the B-58 boasted many firsts for an aircraft defensive gun including the first fully automatic defensive gun fire control system for a production aircraft, the first aircraft gun unit to use a 3-axis inertially-stabilized platform to increase the gun's accuracy, the first aircraft gun to use a self-contained environmental control unit for the gun and ammunition storage, first aircraft gun to use a solid state analog fire control computer for fire control and the first to use a hinged turret arrangement for maintenance work.

The forward muzzle velocity of the 20mm T171 cannon was lower than the forward velocity of the B-58 when it was flying at Mach 2. So relative to the ground, the cannon round would be moving backwards when leaving the muzzle!

Source: Convair B-58 Hustler: The World's First Supersonic Bomber by Jay Miller. Midland Publishing/Aerofax, 1997, p104-105.

26 October 2009

The introduction of the MAD sensor (magnetic anomaly detection) posed a problem with the current anti-submarine weapon of the day, the depth charge or depth bomb. US Navy squadron VP-63 got its Consolidated PBY-5A Catalina flying boats modified with MAD stingers in 1942. As the Catalina had to fly low over the surface of the water to detect the magnetic signature of a submerged U-boat, by the time the depth bomb was released, the aircraft's forward motion would carry the bomb ahead of the intended target.

As a solution, scientists at CalTech designed the "Retrorocket" which was an air-launched rocket based on the ship-launched Hedgehog antisubmarine rocket. The retrorocket weight 65 lbs with a 35 lb warhead and solid rocket motor in the tail with a ring fin assembly for stability. The retrorocket was mounted under the Catalina's wings pointed aft. Once the MAD sensor detected the U-boat, the rockets fired aft to fall vertically at the point where it had been fired as the forward facing rocket canceled out the forward speed of the launching aircraft.

Flying only 100 feet above the sea, the Catalinas of VP-63 based at Port Lyautey, Morocco, partrolled the Strait of Gibraltar to prevent U-boats from reinforcing the Mediterranean. In 1944 U-761 was the first casualty of the MAD Cats of VP-63. U-618 tried to run the Strait but turned back to France. Then U-392 tried to run the gauntlet and fell to a combined attack by MAD Cats and surface ships. Three U-boats would later sneak in successfully by avoiding the deep water channels altogether. U-731 then was sunk again and following that, one more U-boat made it past the strait, but the German effort proved excessively costly as by this point in the war every U-boat was valuable.

Source: Aeroplane, October 2009. "Mad Cats and Mousetraps" by Dr. Alfred Price, p17-21.

21 October 2009

The Legacy of the Northrop XP-56 "Black Bullet"

The lasting legacy of the Northrop XP-56 "Black Bullet" isn't its configuration but rather how the development of the aircraft changed the way metal alloys were used in aircraft and that in turn, changed the way metal alloys were handled in other industrial applications outside of aircraft manufacturing. At the time Northrop got the contract to develop the XP-56, aluminum alloy production was insufficient to meet forecast demands for just the aircraft industry alone in the 1939-1940 timeframe. Many manufacturers turned to alternative materials such as Duramold, wood, and even stainless steel.

Jack Northrop, however, always had an interest in advanced materials applications besides unconventional aircraft configurations. While working for Douglas in the 1930s, he got interested in the use of magnesium sheet but because it was a relative unknown in the industry of the day, he got little support from Donald Douglas. When he left Douglas to start his own company in 1939, use of magnesium sheet at the time was considered unworkable as it couldn't be riveted with aluminum alloy rivets due to galvanic corrosion and welding was difficult at best.

But magnesium was abundant in land deposits and seawater and its 2/3 lighter weight than comparable thickness aluminum alloy sheet allowed thicker skins and parts for an equivalent weight. With welding seen as the only viable way of working with magnesium sheet in an aircraft, Northrop hired an associate from Douglas, Vladimir Pavlecka, to develop a way of efficiently and cleanly welding magnesium. The end result of Pavlecka's work resulted in Heliarc welding and the patenting of the Heliarc welding torch which quickly found industrial applications outside of aircraft manufacturing. Northrop and Pavlecka's Heliarc welding eliminated the use of flux or a flux-based electrode as in conventional welding- use of flux on magnesium caused a weak and porous weld seam. Using a tungsten electrode, a stream of helium was used to eliminate atmospheric oxygen from the local environment at the tip of the torch, resulting in a high quality magnesium weld.

On the XP-56, the assembly jigs were used to hold magnesium sheet in place and then the interior was welded to the sheet's inside. So quite literally, the aircraft was built from the outside to the inside! With no rivets, the skin of the XP-56 was very smooth and so stiff that the aircraft didn't even need main wing spars in its design.

In someways developing Heliarc welding was the easiest problem to solve- Northrop's engineers devoted considerable effort into getting good quality magnesium sheet that was flat and the stout assembly jigs and welding fixtures were a first in any industry.

American Secret Pusher Fighters of World War II: XP-54, XP-55, XP-56 by Gerald Balzer. Specialty Press, 2008, p111-126.

20 October 2009

Based on the layout and delta configuration of the Avro Vulcan, the Avro Type 722 Atlantic was first proposed in June 1953. The original configuration of the Atlantic had the four engines next to the fuselage as in the Avro Vulcan, but as engineering and design work proceeded, by the time of the Farnborough Air Show in 1953 the engine pairs were moved outward halfway on the wings.

Engines were to have been in the same class as either the Olympus engines used on the Vulcan or the new Rolls-Royce Conway turbofan. The fuselage of the Atlantic was circular in cross-section with a diameter of 12.5 feet which allowed five-abreast seating for up to 120 passengers in rear-facing seats. The cabin was divided in two by a centrally-located galley which could be augmented by a bar/lounge area as well. With a length of 143 feet and a wingspan of approximately 119 feet, the Avro Atlantic would have been able to carry its passengers at a range of nearly 6,000 miles at 40,000+ feet at speeds like that of the Avro Vulcan.

Despite the publicity efforts of Avro, no interest was forthcoming in the Atlantic.
Source: Avro Vulcan: Britain's Famous Delta-Wing V-Bomber by Phil Butler and Tony Buttler. Aerofax/Midland Publishing, 2007, p55.

19 October 2009

At the end of the first year of active service of the Convair F-106 Delta Dart, the USAF used it to set a world's absolute speed record. On 15 December 1959 Major Joseph Rogers flew aircraft 56-0467 to 1,525.695 mph on an 11-mile straight line course at Edwards AFB, beating the existing world record of 1,483.84 mph set in 1956 by a specially-modified Mikoyan-Gurevich Ye-166.

Major Joseph Rogers (known as "Whistlin' Joe") was a Korean War veteran and was at the time the project officer for F-106 integration at the Air Defense Command's HQ. He later would command the 317th Fighter Interceptor Squadron at Elmendorf AFB and after that, headed the SR-71A/YF-12A Test Force. His final assignment with the USAF would be as Chief of Staff for Operations at the ADC HQ.

A placard was placed in the cockpit of 56-0467 when it was assigned to the 329th Fighter Interceptor Wing. The placard read "This F-106 - number 60467 - set a world's speed record of 1525.95 mph over a 15/25 kilometer course Dec. 15, 1959, at Edwards AFB, Calif. Pilot was Major Joseph W. Rogers." Unfortunately 56-0467 was lost at George AFB, California, when the right main tire blew out on takeoff, causing the main gear to collapse. The aircraft was destroyed in the ensuing fire but the pilot, Ken Robken, safely escaped.

Although the F-106's speed record bested by the Lockheed SR-71 just a few years later, the F-106's record still stands to this day as the fastest speed ever attained by a single-engined jet aircraft in the world while in level flight.

Source: Convair Deltas: From SeaDart to Hustler by Bill Yenne. Specialty Press, 2009, p133-135.

17 October 2009

The first electric-powered two seat airplane to fly at AirVenture 2009 at Oshkosh, the Yuneec E430 is an LSA (light sport aircraft) class aircraft that is the first commercially produced electric-powered aircraft. Manufactured by a Chinese company, Yuneec International, headed by Asian entrepreneur Tian Yu, the company already has the first phase of its factory outside of Shanghai operating with 250 workers. The proof-of-concept aircraft first flew just before Oshkosh and by the time of the show had accumulated 40 hours of flight time as part of its FAA certification.

With long span wings and a glide ratio of 25:1, the E430 is more like a motor glider with an empty weight of only 550 lbs and a maximum weight of 1050 lbs. It has a 40 kilowatt electric motor (equivalent to 50 horsepower) spinning a three-bladed prop. Three rechargeable lithium-ion battery packs provide 1.5 to 2 hours of flying time and there is an option for a five battery pack with just over 2.5 hours of flying time.

The E430 is already available for order with a quoted cost of $89,000 ready to fly with a complete electric power package.

Source: Flying, November 2009. "Electrics Emerge" by Robert Goyer, p62-64.

16 October 2009

Noted aviation author Walter Boyne once recounted how the Curtis XP-55 Ascender got its name from a Curtiss employee naming contest. Curtiss had already had one such contest that resulted in the C-46 transport getting the name "Commando". Two of the lead engineers on the XP-55 project, George Page and Edward "Bud" Flesh (Flesh would go on and lead the team that designed the McDonnell XF-88 that became the F-101 Voodoo) were one day lamenting the numerous technical problems facing the project and Bud Flesh finally said out of frustration "George, I know one thing; if they ever have a contest for this bird, I'm going to call it 'Ascender'." Not realizing the double-entendre intended by the tail-first design, the XP-55 ended getting that very name suggested originally in jest.

American Secret Pusher Fighters of World War II: XP-54, XP-55, XP-56 by Gerald Balzer. Specialty Press, 2008, p103.

15 October 2009

The 34th Air Division of the People's Liberation Army Air Force (PLAAF) of China operates 8 Boeing 737-300s and two 737-700s for VIP transport of government and military officials. Delivered between 1988 and 2003, the Boeing twins replaced a mixed fleet of Ilyushin Il-18 turboprops and Hawker Siddeley HS.121 Trident 2B jetliners that had been using in the VIP role since the early 1970s. The fleet operates in a quasi-civil red and blue scheme.

Two of the 737s, however, that were purchased from Garuda Indonesia in 2000, serve in the airborne command post role. The two aircraft were registered as B-4052 (ex PK-GWI, MSN 24701/LN 1957) and B-4053 (ex PK-GWJ, MSN 24702/LN 1994) and were converted by Xian Aircraft Co. with a dorsal-mounted teardrop fairing ahead of the wings (presumably a SATCOM antenna) and two smaller ventral teardrop fairings for and aft of the wings that likely serve the specialized communications suite. The two airborne command posts also wear a gray low-visibility finish with a Chinese flag on the tail.

Some controversy exists as to whether the modification of these aircraft constituted a violation of Sino-American trade agreements and export laws.

Source: Chinese Aircraft: China's Aviation Industry since 1951 by Yefim Gordon and Dmitriy Komissarov. Hikoki Publications Ltd, 2008, p251.

14 October 2009

In cooperation with the CEV (Centre d'Essais en Vol), the government flight test center and ONERA (Office National d’Etudes et de Recherches Aérospatiales), the French aerospace lab, Aérospatiale modified a Canadair/Lockheed T-33AN into a supercritical wing research testbed. Since 1972 Aérospatiale had been engaged in the study of a subsonic supercritical wing for civilian use (ostensibly for the nascent Airbus Industrie). The T-33 which was used by the Armée de l'Air at the time for flight training was dubbed the Pégase which was itself an acronym that stood for Programme d'Etude Générale d'une Aile Supercritique Epaisse, or "Thick Supercritical Wing General Study Program".

A supercritical wing would have allowed an increase in flight performance across a wide range of subsonic speeds and despite being a thicker wing, it would have allowed for a higher Mach cruising speed. In jetliners, a supercritical wing holds more fuel due to its thickness without sacrificing high speed cruising speeds yet low speed performance will also be enhanced.

Using balsa, textiles, and resins, engineers reshaped the Pégase's wings into various supercritical profiles. It made its first flight on 13 April 1977 with Alain Guillard at the controls and it would go on to make 74 test flights with its last flight on 2 May 1978. During flight testing, the straight-winged Pégase was able to cruise in level flight at Mach 0.8. The Pégase was never returned to its original configuration and is presently in storage at Le Bourget in Paris awaiting restoration for display.

Source: Wings of Fame, Volume 16. AIRtime Publishing/Aerospace Publishing, 1999, "T-Birds and Silver Stars: Lockheed T-33/T2V Variants by Robert F. Dorr, p123.

13 October 2009

During the definition phase for the Lockheed T2V-1 SeaStar carrier-based trainer version of the T-33 Shooting Star, one T-33 was modified with twin vertical tails as part of program to see if the post-stall stability of the T-33 could be improved. The Navy had concerns about the stability in the carrier landing pattern of a naval adaptation of the T-33.

Aircraft 51-4263 was modified with an enlarged horizontal tailplane with rounded end vertical fins. The rear fuselage tailpipe was also modified and some accounts also note a rudimentary arresting system added to the underside of the fuselage as well. Various shapes and materials were also trialled on this particular aircraft before it was returned to stock T-33 configuration.

The project was never publicized by Lockheed and Naval History Office has no records of this aircraft. Sometimes called NT-33, according to two individuals who worked on it it had no formal designation. The twin tail configuration was never adopted for the SeaStar as Lockheed elected to enlarge the vertical fin and move the horizontal tailplane further up the fin on the production T2V-1.

Source: Wings of Fame, Volume 16. AIRtime Publishing/Aerospace Publishing, 1999, "T-Birds and Silver Stars: Lockheed T-33/T2V Variants by Robert F. Dorr, p111-112.

12 October 2009

In October 1952 the US Air Force initiated the development of SAGE (Semi-Automatic Ground Environment), an integrated set of radar, SAMs, and interceptor aircraft all tied together by digital computers and long distance telephone links. At the time of the inception of SAGE, there was only one digital computer in existence, the Whirlwind at MIT. Very quickly the SAGE project would eclipse the Manhattan Project in terms of size and complexity as much of the technology had to be developed to develop the world's first integrated air defense system. IBM would win the contract in April 1953 to develop the computers that would be the core of SAGE.

Called Whirlwind II by IBM but AN/FSQ-7 by the USAF, the FSQ-7 was the world's first production digital computer weighing 275 tons with 919 miles of cable, 50,000 vacuum tubes, 7,300 pluggable units and 170,000 diodes. The computer consumed 3 megawatts of power and required 100 operators.

The magnetic core of the FSQ-7 had 256 kilobytes of memory and was supported by 150 kilobyte magnetic drum as well as 4 tape drives each holding 100 kilobytes of data. One-hundred fifty consoles displayed data on circular CRT screens that used light pens to interact with the screen information. With the light pens, operators could tag radar tracks and issue commands to air defense units. Each of the 24 SAGE director centers built had a large multistory hardened concrete structure housing two FSQ-7 computers- one running and the other one operating as back up to the first. Each of the director centers were then linked not only to each other but to also as many as 100 air defense units by long distance telephone lines.

SAGE was the single most expensive defense project until the development of the ICBM. The first direction center went online at McGuire AFB in New Jersey in November 1956 with the last one completed in 1962. SAGE ran continuously for the Air Defense Command and NORAD until it was decommissioned in 1983.

Much of what IBM learned in the development of SAGE went into its next major computer network project, an airline reservations and booking system for American Airlines that went online in 1960 called SABRE (Semi-Automatic Business Research Environment). Many of the developers of SAGE also went on to establish the ARPANET, the military predecessor of today's Internet.

Source: Valkyrie: North American's Mach 3 Superbomber by Dennis Jenkins and Tony Landis. Specialty Press, 2005, p53-54.

11 October 2009

In Vietnam most Martin B-57 Canberra combat operations were carried out by two squadrons, the 13th and 8th Bomb Squadrons. With a rear echelon base at Clark AB in the Philippines, in 1965 B-57 operations set up shop at Da Nang AB in the northern part of South Vietnam. The two squadrons alternated 60-day deployments to Da Nang, with one squadron in combat while the other squadron rested and trained at Clark. The first missions out of Da Nang were flak suppression sorties to protect the Ranch Hand defoliant spraying flights of C-123 Providers. Going into 1966, missions expanded to include sorties over the Ho Chi Minh Trail as well as night missions over North Vietnam.

The missions over North Vietnam were the most dangerous for the B-57 crews and only the most experienced crews were assigned missions "up north". These missions became known as "Doom Pussy" missions- crews that flew them were entitled to wear a special patch on their flight suits of the "Doom Pussy"- a yellow and orange cat with an eye patch eating a B-57 with the Vietnamese phrase "Trong Mieng Cua Con Meo Cua Tham Phan" which translated as "I have flown into the jaws of the cat of death". Returning crews to Da Nang, after experiencing the abundant AAA fire up north would simply say "I have seen the Doom Pussy".

The cat got its name from the Da Nang Officers Open Mess ("DOOM"). In the bar was a wooden sculpture of a cat that was present before the B-57s arrived at Da Nang in 1965 and when there was a B-57 mission into North Vietnam that night, the cat sculpture was turned to face the wall until the crews returned safely from that night's Doom Pussy missions.

Source: Martin B-57 Canberra: The Complete Record by Robert Mikesh. Schiffer Publishing, 1995, p90-93.

10 October 2009

During the development of the Antonov An-124 Ruslan, studies were done on how best to transport the large wing panels and wing center section from their place of manufacture in Tashkent to the Antonov final assembly plant in Kiev. Air transport was found to be the most efficient solution and to this end, Antonov modified the An-22 prototype to carry the wing sections externally on the aircraft's back.

Two forward attachment points were mounted on the An-22's wing center section and two rear attachment points were mounted just aft of the wing. The attachment points were then connected to internal bracing inside the cargo compartment that in turn mounted to the cargo deck floor. The whole external structure was then faired. Additional attachment points were mounted just above and aft of the flight deck. To provide additional directional stability, a stock An-26 vertical fin with the rudder locked was fixed to the aft fuselage to supplement the An-22's twin vertical fins.

"Special Cargo No. 1" referred to the An-124 wing center section and "Special Cargo No. 2" referred to the An-124 wing panel assembly. On 15 July 1980 the now-designated An-22PZ took off for the first time from Tashkent with the wing center section attached to its back. Though a brief preliminary flight was made the day prior, this was the first delivery flight to Kiev and soon into the flight significant vibrations and buffeting set in caused by a failure of one of the forward attachment points. Though the flight made it safely to Kiev, it led to a redesign of the fairings used on the cargo itself as well as the attachment points. The opportunity was also taken to add a 1000-liter alcohol deicing system for the cargo.

The first flight with the wing panel assembly took place in February 1982 and by 1983 regular An-22PZ flights were now taking place from Tashkent to assembly plants both in Kiev and Ul'yanovsk. These special flights lasted until 1988 but six additional flights took place between 1987 and 1994 to deliver wing sections for the An-225 Myria.

In 14 years of operation, over 100 flights took place safely.

Source: Antonov's Heavy Transports: The An-22, An-124/An-225, and An-70 by Yelfim Gordon, Dmitriy Komissarov and Sergey Komissarov (Red Star Volume 18). Midland Publishing, 2004, p27-31.

08 October 2009

In 1960 the British aircraft manufacturer Vickers gave an extensive contract proposal to Pan American World Airways on a custom-tailored version of the VC-10 airliner for the airline's centerpiece trans-Atlantic routes. Pan American was in need of a prestige jetliner for its transcontinental and Pacific routes as well. What was needed was a 200-seat jetliner with nonstop capability across the Atlantic in all but the most severe winter conditions.

With an American-designed interior (by Butler of New York), the Pan American VC-10 featured a developed version of the Rolls-Royce Conway engine with 24,000 lbs of thrust designated the Conway 7 as well as prominent leading edge root extensions on the wings that housed more fuel as well as increasing the wing area. Wingtip fuel tanks were also a part of the design for a total fuel capacity of over 24,000 US gallons. An underfloor compartment could be used as a passenger lounge or a crew rest area and, in a prescient move, Vickers developed a two-crew flight deck using cathode-ray tube displays in one of the first proposals for a glass cockpit. There was a third crew member in the flight deck referred to in Vickers' proposal as an "engineering and systems manager".

Also part of the proposal was an all-cargo version of the VC-10 that featured straight-in loading via a swing nose developed for the unbuilt VC-10 F4 freighter. A roller-bearing loading floor would ease the loading of palletized cargo long before palletized cargo became a reality.

Although the negotiations never bore fruit, it was considered very serious business by Vickers as a copy of the proposed contract is in the Vickers archive at the Brooklands. It was a proposal ahead of its time, a fleet of highly efficient passenger and cargo variants that would have provided a common fleet without having two totally different aircraft types.

Source: Vickers VC-10 by Lance Cole (Crowood Aviation Series). The Crowood Press, 2000, p93-95.

07 October 2009

The first production version of the Vought F7U Cutlass, the F7U-1, had many shortcomings that were to be rectified in the next version, the F7U-2. Only 19 F7U-1s were built by Vought at their Grand Prairie, Texas, facility. Nearly all were used exclusively for Vought flight testing and evaluation by US Navy test pilots. The exception came when when two F7U-1s were forced upon the Blue Angels in 1952 as an adjunct to the team's existing Grumman F9F-5 Panthers.

Vought had successfully lobbied its supporters within the Navy's BuAer and OpNav to assign the two F7U-1s to the Blue Angels for the 1952 season as a publicity exercise to drum up more support for the mediocre fighter aircraft. In the early part of the 1952 season, the team's Panthers were grounded temporarily due to fuel control problems and when the F7U-1 Cutlass worked, it performed to astonished crowds as it demonstrated its afterburners (the Cutlass was the first Navy jet to designed from the outset to have afterburners), its 540-degree per second roll rate as well as its exotic tailless configuration.

However the Cutlass was a maintenance headache and the pilots frequently encountered a serious of design problems and inflight emergencies and when the grounding of the F9F-5 Panther ended later in the show season, the Blue's maintenance officer and the two Cutlass pilots wanted the aircraft grounded permanently. After a final demonstration at NAS Memphis (home of the Navy's Technical Training Center), the F7U-1s were left behind to become, ironically, maintenance ground trainers.

Source: US Naval Air Superiority: Development of Shipborne Jet Fighters 1943-1962 by Tommy H. Thomason. Specialty Press, 2007, 112-114.

06 October 2009

Probably the first attempt at an all-in-one hunter-killer aircraft to hunt down and destroy enemy radars came in 1944 with the Royal Air Force's Project Abdullah. Unlike US efforts that focused on radar-finding aircraft to cue attacking aircraft, Project Abdullah consisted of an electronic radar hunting device fitted to three Hawker Typhoons of the No. 1320 Special Duty Flight in May 1944.

In the cockpit of the Typhoon was a CRT display connected to a radar homing receiver. The receiver was tuned to the known operating frequencies of the German radar. Once in the vicinity of a suspected radar site, the pilot turned on the Abdullah equipment and once alerted to an active radar site, he would try to visually locate the site and either attack it or fire smoke marker rockets to mark it for further attack by waiting aircraft.

Despite an impressive step forward in the suppression of enemy air defenses (SEAD), the German countermeasures were as simple as either turning off the radar knowing the Abdullah aircraft were in the area to changing the radar frequency as the homing equipment on the Typhoon had to be preset before takeoff.

Source: Wild Weasel Fighter Attack: The Story of the Suppression of Enemy Air Defenses by Thomas Withington. Pen & Sword Books, 2008, p23.

05 October 2009

During the development of the Boeing 747SP, a combination passenger-cargo version called the SP Combi was proposed. With a large main deck cargo door in the aft fuselage, the SP Combi was billed as the ideal replacement for the aging fleet of Boeing 707 and Douglas DC-8 aircraft as it could fly 186 passengers and nearly 65,000 lbs of cargo farther and with better economics than a 707-320C with 147 passengers/6,800 lbs of cargo or a 707-320C freighter with 58,000 lbs of cargo.

The SP Combi's 328 seat all-passenger configuration could be quickly converted over to either a 242-passenger/four-pallet arrangement or a 186-passenger/eight-pallet arrangement. To test the idea, a China Airlines 747SP was used to test the accessibility of the main deck cargo door with standard main deck loading equipment given that the 747SP's wing trailing edge was much closer to the aft fuselage location of the proposed door than on the full size 747 Combi aircraft. Black tape was used to outline the door location and tests were successful. However, the airlines showed little interest and no SP Combis were produced.

Source: Boeing 747SP by Brian Baum, Great Airliners Series, Volume 3. World Transport Press, 1997, p41.

04 October 2009

In October 1961 NORAD mounted its largest-ever air defense test, Exercise Skyshield. In order to be as fully realistic as possible, the Strategic Air Command's Boeing B-47 Stratojet and B-52 Stratofortress units would try to penetrate NORAD's radar and fighter defenses. In addition, No. 27 and No. 83 Squadrons of the Royal Air Force's Bomber Command each sent four Avro Vulcans to participate in Skyshield. No. 27 Squadron's four Vulcans were deployed to Kindley AFB, Bermuda, to penetrate the defense net from the south and No. 83 Squadron's four Vulcans were deployed to RAF Lossiemouth in Scotland to penetrate from the north.

On 14 October Exercise Skyshield began in earnest with the incoming bombers taking off. The northern attack began with the B-47s coming in as low as 500 feet to jam out the ground radars. Behind the Stratojets came the B-52s at 35,000 to 42,000 feet supported by jamming by EB-57 Canberras. And behind the Stratofortresses came the Vulcans at 56,000 feet. The heavy jamming was so effective that only the first Vulcan detected the radar of an F-101 Voodoo. Although NORAD scrambled many fighters, they concentrated on the B-52s and by the time the Vulcans arrived, they lacked the fuel to climb to 56,000 feet. No. 83 Squadron's Vulcans reached their target points all unscathed (which was to land at a base in Newfoundland).

The southern wave followed and used similar tactics only this time the four Vulcans from No. 27 Squadron were on their own. The four Vulcans approached the US Northeast on a broad front with their systems in full ECM and jamming. Fifty miles from the coast as defending F-102 Delta Daggers were scrambling, the southernmost Vulcan turned north and flew behind the other three Vulcans and was effectively masked by the onboard jamming of those three bombers. While the Delta Daggers swarmed the other three Vulcans, the fourth Vulcan penetrated unscathed and undetected to reach its target (which was to land at Plattsburgh AFB in upstate New York).

Source: Vulcan Units of the Cold War by Andrew Brookes, Osprey Combat Aircraft #72. Osprey Publishing, 2009, p21.

03 October 2009

An act of Congress signed on 12 July 1921 officially created the Naval Aviation Observer to partner with naval aviators on multi-crew aircraft. The same act created the US Navy Bureau of Aeronautics (BuAer) and specified that BuAer's chief must be a qualified pilot or as the newly-created naval aviation observer. As a result, the first Chief of BuAer, RADM William A. Moffett, entered flight training and in June 1922 became Naval Aviation Observer No. 1.

Following the creation of the NAO, duly-qualified crew served in a wide variety of aircraft that required specialized, non-pilot crew. By the postwar period in the 1950s, both officers and enlisted personnel filled roles from bombardiers and radar operators to navigators and flight engineers. Most, however, were enlisted men. For instance, nearly all of the radar operators on the Douglas F3D Skyknight were enlisted or warrant officers. In the heavy attack squadrons, the bombardiers were all uniformly enlisted.

However, with the arrival of advanced aircraft in the 1960s like the Grumman A-6 Intruder and the McDonnell F-4 Phantom II, the NAOs became indispensable in the operation of the new generation of aircraft. In the A-6 community, the bombardier/navigator (B/N) was considered so vital to the employment of the Intruder that the early B/Ns who were enlisted were converted over to Limited Duty Officer status.

As a result, on 8 February 1965 the Navy's Bureau of Personnel replaced the designation "Naval Aviation Observer" with "Naval Flight Officer" and by 1968, newly-minted NFOs received wings like the aviators only the NFO wings had two crossed anchors.

Source: Intruder: The Operational History of Grumman's A-6 by Mark Morgan and Rick Morgan. Schiffer Publishing, 2004, p21-22.

02 October 2009

One of the unique features of the Ilyushin Il-62 jetliner was the twin wheel telescoping strut that retracted vertically into the aft fuselage to keep the aircraft from tipping on its tail when parked or taxiing in an unloaded condition.

The reason that the Il-62 can tip on its tail easily was done for aerodynamic reasons. Unlike most aircraft that have the main landing gears aft of the empty and loaded center of gravity, the Il-62's main landing gears are behind the aircraft's loaded center of gravity but ahead of the unloaded center of gravity. This results in the need for a lower nose up pitching moment at takeoff when the aircraft is loaded as the pivot point at rotation (the main landing gears) are closer to the loaded center of gravity than what would normally be the case for most aircraft.

As a result, the horizontal tail area could be reduced which resulted in weight savings and reduced drag in cruise flight. The Vickers VC-10 by comparison had a large horizontal tail area of 645.9 square feet compared to the Ilyushin Il-62's at 430.6 square feet.

Source: OKB Ilyushin: A History of the Design Bureau and Its Aircraft by Yefim Gordon, Dmitriy Komissarov and Sergey Komissarov. Midland Publishing, 2004, p255.

01 October 2009

After the end of hostilities in the Korean peninsula in 1953, the Douglas F3D Skyknights of Marine Corps squadron VMF(N)-513 continued to fly night patrols to stop North Korean Polikarpov Po-2 biplanes from crossing the DMZ. On some nights, even North Korean MiG-15 would test the waters by making runs across the DMZ and dashing back north before they could be intercepted by the F3D patrols.

The Marine Corps came up with a joint tactic with the USAF to stop the intruding flights by the MiG-15s which in some cases were too fast for the F3Ds. At South Korean air base K-55, the USAF had some F-86 Sabre units in residence. But the Sabres lacked nocturnal capability as they didn't have an air intercept radar. So in a tactic called "Mad Dog", an F3D would radio K-55 when five miles out with an F-86 at the end of K-55's runway ready to roll. The Skyknight then radio in again when one mile out and that was the F-86's signal to begin its takeoff roll.

As the F3D passed low over the runway, the F-86 pilot would lift off and follow the glow from the twin engine tailpipes of the Skyknight. If the F3D Skyknight couldn't catch up with the MiG-15, they "launched" the F-86 and used their air intercept radar to guide the Sabre pilot to the intercept, much like a miniature AWACS system.

After several Mad Dog sorties, the North Korean MiGs stopped their noctural provocation flights across the DMZ.

Source: Combat Aircraft, October 2009. "US Navy Fighters of the Fifties- Skyknight" by LCDR Rick Burgess USN (Ret), p87.