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Airborne Aircraft Carriers: Wing tip coupling giving a “free ride” to Fighters.

By 23/12/2018Blog

In this DAKOTA HUNTER BLOG,  you will read about the concept of the Post-War Airborne Aircraft Carriers. During WWII, the flight range of the USAF  long-distance bombers made huge leaps forward with every new model that came out. Rapid technological development in Aero Engine Power output allowed upscaling to unprecedented dimensions of the airframe, wings, and internal fuel tanks. All that extra fuel stretched the flight range to well over 10.000 miles!

While the mid-war (1943) launched B-29 Flying Fortress had a max flight range of almost 6000 miles, the post-war B-36 Peacemaker (operational from 1948-1958) could perform with a max flight range of 10.000 miles/ 16.000 kms.
In contrast to that development, the first generations of (post-war) Jet Fighters were reputed as “Gas-Guzzlers” and therefore had extremely short flight ranges. Even the mounting of wing-tip and/or belly tanks did hardly bring any relief that could help those fighters to escort the strategic Bombers during the Cold War on their long intercontinental flights (read to Russia and back).
C-47A wingtip coupled 3 Q-14B
The photo above shows history’s first in-air coupling of two separately flying aircraft and subsequently, the switch-off of the smaller aircraft’s engine.
This novel concept was tested with the good old Douglas C-47 Skytrain.  As from Aug 1949, Major Clarence E. “Bud” Anderson did remarkable experiments with a system of wing tip coupling of 2 aircraft while in flight. The smaller single-seater airplane Culver Q-14 Cadet had a pointed lance mounted on its wingtip and flew that into a ring, mounted on the C-47 wing tip, as such making a coupled pair (see photos on top and below).
 Tom Tom coupling left front wing tip lance ring l
This photo above shows the Middle Ages Game-style Lance and Ring, both were used on the Q-14 Cadet and the C-47 wing tips, to ease the coupling in flight.
The basic idea behind the in-air coupling was to increase the aspect ratio of a wing with more wing surface from another plane, offsetting the additional drag of the smaller plane. I.e. the smaller plane could fly  ‘for free’ with its engine shut-off, as a parasite, coupled with the larger plane.
  C-47A wingtip coupled Q-14B tom tom
If one would extend this inventive plan to a Long Distance Bomber, such plane could tow 2 fighters on both wingtips, flying as “freewheeling” escorts with their own engines shut off and only “awakening to action” when needed with an imminent enemy threat. The mothership hardly sacrificed on its max range and speed with the towing, while it had two fighters in direct close support, just in case hell might break loose with Migs showing up at the horizon. The “bodyguard” Jets would simply start their engines, uncouple from the Master, execute the interception and beat the Iwans out of their airspace. After the pounding, they could return to hook on again for a drink or two, a free refill of their tanks (and oxygen) via the mothership.
 B-29 wingtip coupled to F-84
The photo above: the idea of the flying Aircraft Carrier was born and developed into a steady program of testing and upscaling of aircraft.
While the C-47/ Q-14 experiments were successfully continued into 1949, the more serious tests came with Project Tip-Tow, involving the much larger EB-29 Superfortress that was coupled to two EF-84 D’s Thunderjets in April 1950. The coupling mechanism became more complex, an electronic autopilot was added and the coupling lance could transfer jet fuel and oxygen to the ‘slave’ Fighters, keeping their pilots in high alert and their fuel tanks fully topped-off at any time.
A very serious accident hampered the development when a left wingtip coupling was made between an EB-29A and an F-84D. Right after the autopilot was switched on, the nose pitched up and the F-84D Thunderjet rolled suddenly to the right over its fixed coupling or “hinge” with the mothership. In that flip, the F-84 turned upside down and hit the outer wing panel of the B-29. Explosive bolts for jettisoning the F-84 went off but too late to release the Fighter in time and prevent her from slamming into the Bomber’s outer wing.
The Superfortress’ left wing folded due to the impact and the combo crashed. Fighter pilot John Davis and 5 crew members in the B-29 were killed in this fatal accident.
 B-36 wingtip coupling
Nevertheless, the experiments were to be continued as Project Tom-Tom in 1955/56, this time using the much larger Convair B-36 Peacemaker as the mothership, with the RF-84 F Thunderflashes as slaves (see photo above).

But in the end, all wingtip-coupling tests came to no avail, as the larger long-distance Airborne Tankers based on the modern heavy Bomber designs arrived on the scene. It was this Tanker-converted Bomber aircraft that could provide in a simpler way the much-wanted flight-range extension to the thirsty escorting Jet Fighters, by means of a much less risky coupling and refueling system with a basket-shaped ‘nipple’ that flies behind the Tanker aircraft on a long tube or boom.

Nowadays in Aerial refueling, also referred to as air refuelingin-flight refueling (IFR), air-to-air refueling (AAR), there are two main refueling systems: The probe-and-drogue, which is simpler to adapt to existing aircraft, and the flying boom, which offers faster fuel transfer, but requires a boom operator’s supervision.

As from 1950, the KC-97 Stratofreighter was the first large-scale operated strategic aerial refueling Tanker, a variant of the Military Cargo transport C-97. In the passenger transport role also known as the mighty Boeing Stratocruiser B-377, that was developed straight from the B-29 Superfortress of WW II fame.
Below, you’ll see a 1947 advertisement of the Boeing Factory, comparing the legendary Boeing B-29 Superfortress with its post-war offspring, the Boeing B-377 Stratocruiser that came in the Miltary version as the C-97 Stratofreighter and the KC-97 Stratotanker. It was this long-distance Tanker aircraft KC-97  that would indirectly lead to the demise of the Flying Aircraft Carrier concept with the coupling system of two Jet fighters on every wing tip.
(Photo & Info courtesy: Clarence “Bud” Andersen, Goleta Air & Space Museum)
  Boeing B-377 ad
This concept of the airborne Fuel Gas Station is still operational and widely used by most Air Forces all over the World, in order to extend the flight range of their Jet fighters. There are now more advanced Jet engines, with way better fuel economy than what they used to have in the 1950s, but that edge has been traded in for more speed with afterburners and way more payload with awesome weapons systems. With the (still) relatively short flight range of any interceptor Jet, the Airborne Tanker is by now an indispensable tool in modern air-superiority strategies.
 
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 .Review DH Air Classics July 2015
Enjoy,  Hans Wiesman
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