28 May 2016

CHECK SIX: The F-4 Phantom's F3H Demon Roots

With yesterday being the 58th anniversary of the F-4 Phantom II's maiden flight, here's some interesting trivia. There is actually a continuous line of evolution from the McDonnell F3H Demon to the F-4 Phantom (which was designated F4H when it first flew). This photo is of the full scale mock up of the main missing link that connects the F3H Demon to the F4H Phantom. In 1953, the McDonnell team headed by Herman Barkey was looking at ways of extending the Demon's viability and expanding its versatility. McDonnell had the in house designation F3H-X for the design as it was considered an evolution of the Demon. 

F3H-C "Super Demon": This design was first, it was powered by a single J67 engine. The J67 was to be have been a license-built version of the Rolls Royce Olympus. No J67s were ever built in the US and the Navy wasn't keen on an unproven engine. 

F3H-E: This was different enough from the Demon that it was given the Model 98A designator. It was also powered by the J67 but had a bigger wing than the Demon and had a level stance on the ground instead of the nose-high stance of the Demon.

Full scale mock up of the F3H-G design

F3H-G (Model 98B): This one had twin J65 engines, a license built British Sapphire engine like that used on the Hawker Hunter. It had lateral intakes that looked more like the Phantoms and exhausts that looked also more like the eventual Phantom design. The Navy was attracted to twin engines for safety. The wing was also further enlarged from the F3H-E. It had four 20mm cannon and had an impressive external stores capability. 

F3H-H: This was was the F3H-G but with two of the then-new and promising GE J79 engines. 

Model 98C: Delta winged version of the F3H-G/98B with J65 engines. 

Model 98D: Delta winged version of the F3H-G/98B with J79 engines. 

F3H-J (Model 98E): Similar to the 98C/D, but with an even larger delta wing. 

Model 98F: Recon version of the 98C. 

Tail section of the F3H-G mockup showing the two different engine sizes-
The J79 was on the right side, the J65 was on the left side.
Barkey's team decided the F3H-G/98B was the most promising of the designs and built a full scale mockup, but one side was sized for the J65 engine and the other side sized for the J79 engine. On 19 September 1953 McDonnell submitted the design as an unsolicited proposal to the Navy. Though impressed with the design, the Navy had already ordered the Grumman F11F Tiger and Vought F8U Crusader for its supersonic fighter needs. The Navy, however, encouraged Herman Barkley's team to refine the design to meet an all-weather attack requirement. This design was submitted to the Navy in 1954 and two prototypes were ordered as the AH-1 which had four 20mm cannon and eleven weapons stations. 

F4H full scale mock up showing the originally
planned trapeze launchers for the Sparrow missiles.
The following year the all-weather attack program was canceled and McDonnell was asked to redesign the AH-1 into a two-seat interceptor with a single centerline station for a 600-gallon fuel tank and AIM-7 Sparrow capability. The J65 engine was dropped from contention when the Chief of Naval Operations selected the J79 engine for the new aircraft which would be designated F4H Phantom II. 

And the rest is history! 

Further reading: 

21 May 2016

CHECK SIX: KLM Becomes the First European Airline Postwar to Serve America

21 MAY 1946: Seventy years ago today, KLM Royal Dutch Airlines was the first European airline postwar to launch scheduled services to the United States with the arrival of a KLM Douglas DC-4 at New York Idlewild Airport (today's JFK Airport). The aircraft was PH-TAR "Rotterdam". After the end of the Second World War, KLM's long-haul fleet consisted of former military Douglas C-54 Skymasters, the military transport derivative of the DC-4. To augment this fleet, right after the war, KLM ordered four DC-4s and PH-TAR was one of these four aircraft. It was delivered to KLM on 12 April 1946 and flew the first US services just five weeks later.

PH-TAR "Rotterdam" arrives in New York City
(KLM Royal Dutch Airlines)
This newsreel clip is in Dutch, but the images are wonderful even for us non-Dutch speakers!

Further reading: 

18 May 2016

CHECK SIX: The Douglas DC-7


Douglas launched the DC-7 program at the prodding of C.R. Smith of American Airlines who wanted a competitor to TWA's Lockheed Super Constellations for the first transcontinental nonstop services. American's requirement even called for the same engines as the Super Constellation, the Wright R-3350 Turbo Compound (the DC-6 used the Pratt & Whitney R-2800 Double Wasp) radial. Douglas didn't think there was a market for such an aircraft, but Smith ordered 25 of what would become the DC-7 for $40 million which pretty much covered Douglas' development costs. To save time and make the most of the $40 million, the DC-7 was a stretched DC-6 with Wright R-3350 engines. The DC-7 was slightly faster than the Super Consellation and could under *ideal* conditions (which was rare) do a nonstop transcon in under 8 hours. 

The first variant of the DC-7 was good for transcon runs but was no better than the DC-6 for oceanic routes. That first variant went exclusively to US operators- American (34), United (57), Delta (10), and National (4). American Airlines inaugurated its own nonstop "Mercury Service" DC-7 flights between Los Angeles and New York Idlewild on 29 November 1953. As the DC-7 had a higher cruising speed than the Super Constellation, the eastbound LA-New York run was made easily in 7 hours, 15 minutes (a fact not lost upon American's marketing department, hence the name "Mercury Service"), but the westbound run from New York to LA couldn't be made within 8 hours. Despite over a dozen modifications to the DC-7s made by American's engineers which included tweaks of the Wright R-3350 radial engines to squeeze every bit of horsepower out of the engines, the DC-7s still couldn't beat the prevailing winds. American's pilot union repeatedly pointed this fact out, but C.R. Smith's influence in Washington left the issue unaddressed by federal regulators. In the following year, federal regulators adjusted the time limit to allow the flight to be made legally and American's DC-7s blocked in at 8 hours, 15 minutes on a westbound nonstop.

The next DC-7 variant was the DC-7B which had uprated engines and more fuel tanks in the engine nacelles which made oceanic crossings possible. Pan American launched its own transatlantic services in the summer of 1955 and South African Airways was finally able to fly Johannesburg-London nonstop.

The final DC-7 variant had longer wings and a stretched fuselage, the DC-7C "Seven Seas". The fuel capacity of the Seven Seas allowed full westbound nonstop transatlantic capability, something that the DC-7B couldn't routinely perform. 

There was a DC-7D which would have Rolls-Royce Tyne turboprops (same engine as the Vickers Vanguard) and a swept back vertical fin, but it never made it off the drawing board as Donald Douglas decided jets were the way to go and development of the DC-8 was given priority. 

Further reading: 

(Photos: Vintage Ad Browser, California Classic Forums)

14 May 2016

CHECK SIX: The Rollout of the Boeing 367-80

14 May 1954: The rollout at Boeing's Renton Field facility of the aircraft that would change jet transport, the Boeing 367-80. Bill Boeing was 72 at the time and had long since divested his holdings in the company he founded, but he was present at the rollout of the the Dash 80 and Boeing's wife, Bertha, christened the aircraft with champagne while the Renton High School band played "Wild Blue Yonder", the USAF theme. I always thought this Boeing photo was cool- it's the Boeing president at the time, Bill Allen, showing the 367-80 to Bill Boeing. 

Allen bet the company on Dash 80, investing $16 million of the company's money to gear up for production tooling before having an order from either any airline or the US Air Force. 

But then again, taking a bold risk was something the company did three times undeniably in its history. The first time was in 1934. Boeing president Claire Egdtvedt proceeded with the Boeing 299 without any orders or contracts from the US Army Air Corps for a four engined bomber- the 299 is better known as the B-17 Flying Fortress. When Egdtvedt took his gamble on the 299 prototype, he asked his friend for guidance- who happened to be Bill Allen, who at the time was the company lawyer.

Almost twenty years later Bill Allen found himself in the same position when he launched what become both the KC-135 Stratotanker and the Boeing 707 with the Dash 80 prototype. 

And about 10 years later, Bill Allen was fishing in Puget Sound with Pan American chairman Juan Trippe when Trippe pressed Allen on building a jumbo-sized jetliner- legend has it that Trippe asked Allen "Would you build it if I buy it?" and Allen responded "Would you buy it if I build it?" and by the end of the day, the Boeing 747 was launched on a handshake. According to aviation author Robert Gandt, Allen thought to himself the 747 "would be the perfect swan song if he could step down knowing that he had launched the world’s mightiest ship of the sky. It would secure Boeing’s future well into the century. Or it could ruin Boeing".

Further reading: 

10 May 2016

CHECK SIX: The Vought V-173 "Flying Pancake"

In the 1930s while at Vought, aeronautical engineer Charles Zimmerman advocated a unique discoid aircraft layout that was a form of a lifting body that became known as a “flying pancake”- such an aircraft would have low drag and high structural strength. The Vought V-173 was built as a proof of concept aircraft that first flew 23 November 1942. The large 16-foot props turned opposite each other, driven by Continental A-80 four-cylinder 80-horsepower engines on each side of the cockpit. The props turned in the opposite direction of the wing vortices, in effect nearly canceling them out which resulted in a significant drag reduction. The low aspect ratio wing-fuselage was rigid and generated a lot of lift that made the V-173 very maneuverable and gave it excellent low speed handling characteristics. High-speed, maneuverability and good low speed handling got the US Navy’s attention and Vought got the contract for a fighter version called the XF5U. Though the XF5U never flew (it was five times the weight of the V-173 and would have been an impressive carrier fighter), the V-173 made 190 test flights with its last flight on 31 March 1947. It resided in long term storage with the Smithsonian before it was restored by Vought volunteers here in North Texas and is now on display at the Frontiers of Flight Museum at Love Field. 

Further reading: 

Photo: JP Santiago

09 May 2016

CHECK SIX: The Area Ruling of the Cessna Citation X

If you look closely at the aft fuselage by the engine nacelles of the Cessna Citation X, it’s pinched in quite considerably to conform with supersonic area ruling, the same reason supersonic fighter jets have “coke bottle waist” mid-fuselages- If you were to plot the cross sectional area of an aircraft from nose to tail, the ideal curve on such a graph would be a smooth elliptical curve. But in most aircraft, the wings, tail, or engine nacelles make that curve “bumpy”- so you can take away some fuselage area by the wings. In the Citation X, the fuselage is pinched in to compensate for the engine nacelles increasing the cross-sectional surface area which is what transonic area ruling- if you didn’t there would be a big increase in drag. The pinching also creates a more constant width channel between the nacelle and fuselage- this keeps air from speeding up locally and then slowing down, which would cause it to become turbulent, also increasing drag (that kind of drag is called interference drag). If you’re going to cruise at Mach 0.92, you’ll need every trick in the aerodynamics book!

Further reading: 

Photo: JP Santiago

04 May 2016

A Giant Ahead of Its Time: The Lockheed R6V Constitution

Before the start of the Second World War, Pan American Airways was the world's biggest operator of large ocean-going flying boats with the Boeing 314, Martin M-130 and Sikorsky S-42 in the fleet that spanned Pan American's worldwide network. However, the airline recognized that the pace of development in aviation technology meant that landplanes would be the dominant airline aircraft of the future. Pan Am worked with Boeing to bring the Boeing 307 Stratoliner to fruition (the world's first pressurized airliner). But with the start of the war for the United States in 1941, Pan American's operations were shifted to support the war effort and in this capacity the airline solicited the US Navy for the construction of a true heavy-lift landplane transport. This was finalized with the US Navy, Lockheed, and Pan American in November 1942 with what became the Lockheed Model 49 Constitution. 

The R6V Constitution on final approach at Moffett Field in California
(Wikipedia/US Navy)
The requirements issued by the Navy as suggested by Pan American were for a range of 5,000 miles, 17,500 lb payload at 255 mph at 25,000 feet cruising altitude. A year later on 1 November 1943 the contract was formally issued to Lockheed. Pan American's engineers led by their head engineer, Andre Priester, worked alongside Lockheed's engineers and their head, Willis Hawkins (he also designed the Constellation and later on would work on the F-80 Shooting Star, F-104 Starfighter, and the C-130 Hercules). The fuselage of the Constitution was a double deck, double lobed cross-section design with the large wing passing through the mid-fuselage between decks. With a fully-pressurized double-deck, the Constitution could carry up to 204 military passengers but the normal complement would be 168 passengers. Pan American's plans were for 51 passengers on the lower deck and 58 passengers on the top deck. Cargo doors were installed on the lower deck and the wings were deep enough to allow mechanics to access the four radial engines in flight for maintenance. The Constitution was also the first large transport aircraft to have multi wheel main landing gear bogies (four wheels to each main landing gear). 

The wing itself was based on the layout and structure of the wings used on the Constellation and the P-38 Lightning. Four 3,000 horsepower Pratt & Whitney R-4360 28-cylinder Wasp Major engines drove four bladed props. Unusually, the upper surface trailing edge root of the wings could hold RATO units to shorten takeoff runs. There were three units in each wing- they were fired when the landing gear retraction sequence started. As the landing gears took 14 seconds to retract, the RATO units burned for 15 seconds.

Takeoff using the overwing integral RATO units
(San Diego Air & Space Museum)
Since the Constitution was a low-priority project during the war, it wasn't until well after the war ended in August 1945 that the aircraft was completed. Though standard for today's design work on modern airliners, Lockheed used a full-scale hydraulic and electrical systems test rig that today would be known as an "iron bird". The system was loaded so the hydraulics and flight control systems would "experience" loads similar to what would be found inflight and were invaluable in letting the Constitution's test pilots get familiar with the large aircraft. The first flight came on 9 November 1946 and after the first 44 flight hours of testing the Constitution was found to be significantly underpowered. More powerful versions of the R-4360 Wasp Major were installed that theoretically produced 3,500 horsepower, but in practice even these engines could only garner 2,900 to 3,300 horsepower and that was with water injection and bypassing the superchargers on takeoff. As a result, use of the integral RATO units was commonplace. 

To keep Pan American interested in the project, Lockheed proposed the civilian version of the Constitution be powered by Wright 5,500 horsepower Typhoon turboprop under development, but by this point Pan American had thrown its lot with the Boeing Stratocruiser and bowed out of the Constitution program. Designated XR6O-1 by the US Navy, the first Constitution underwent a full year of flight testing at NAS Patuxent River, Maryland. The second XR6O-1 made its first flight on 9 June 1948 and unlike the first aircraft, the upper deck was fitted out for VIP passenger service with 92 seats while the lower deck was fitted out to carry as much as 40,000 lbs of cargo. Dual spiral staircases at each end of the cabin provided access to the upper deck from the lower deck and passenger entry was via the nose gear well which was large enough to allow airstairs to be pulled up just in front of the nose gear. 

The Constitution on static display during an open house at San Francisco Airport
(San Francisco International Airport/FlySFO.com)
In February 1949 the second R6O (the X prefix was dropped) was commissioned into service at NAS Moffett Field, California, with the fleet logistics support squadron VR-44. Soon joined by the first R6O, the Navy embarked on a series of publicity flights across the country, using the Constitution to not only transport personnel and materiel, but also to stimulate interest in naval aviation. The R6O carried one and a half times more cargo than the next biggest Navy transport, the Douglas R5D (C-54 Skymaster/DC-4). In 1950, the two R6Os were redesigned R6V; in the Navy's aircraft designation system used prior to 1962, "V" stood for the Vega Division of Lockheed that had built the PV-1 Ventura and PV-2 Harpoon in the Second World War- the "O" of Lockheed was dropped as it could be confused with the number zero and "V" took it's place as the Lockheed designator code. They were reassigned to VR-5 for expanded operational duties that included flights to Hawaii and Alaska. With a total of 3,760 flight hours between the two aircraft, in 1953 the R6O Constitutions were retired and placed in storage at NAF Lichtfield Park, Arizona. The aircraft were offered to the airlines on a proposed five-year lease, but no interest came about. 

The first Constitution ended up in Las Vegas as a promotional billboard for Alamo Airways at McCarran Airport and plans were floated to move the aircraft to the Strip to be part of a casino. However, the plans were never materialized and when Howard Hughes acquired the property that the aircraft sat on, he also gained ownership of the aircraft and had it scrapped in 1970. The second Constitution ended up in Opa Locka, Florida, where it was to be sold to a German businessman who wanted to use it for a restaurant in Barcelona, Spain. The deal fell through and the aircraft mysteriously caught fire which gutted the interior but spared the exterior. After several years of legal wrangling, the aircraft was scrapped in 1979.

Further reading: 

The Convair Model 6: A Jumbo Jet Before Its Time
Pan American and the Boeing 314 Toilet Scandal
The Cadillac of the Constellation Line

Source: Lockheed R6O/R6V Constitution (Naval Fighers No. 83) by Steve Ginter. Ginter Books, 2009.