Grumman F6F Hellcat Color Photographs Part II – Drones

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Grumman produced a total of 12,275 Hellcats. With the end of the war and the dawning of the jet age the F6F quickly became surplus to requirements. Many were transferred to foreign nations or passed on to Naval Reserve units. One of the more interesting uses for the Hellcats was conversion to drones, which allowed the aircraft to be piloted remotely, usually from another aircraft.
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The drones were used for several functions, most commonly for targets. These drones with their colorful tails were used in Operation Crossroads for atmospheric sampling during the 1946 atomic bomb tests.
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A shot of the Operation Crossroads test aircraft with their wings folded on the ramp. The additional antenna wires required for remote operation can be seen at the tops of the vertical tails.
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Another more tactical mission was performed during the Korean War when the Hellcats were converted into flying bombs in the tradition of the WWII TDR and TDN assault drones: https://inchhighguy.wordpress.com/?s=assault+drone This bomb laden F6F-5K drone is seen about to be launched from the USS Boxer (CV-21) off Korea in August of 1952. Douglas Skyraiders were used as controlling aircraft. Note that the bombs lack tail fins as they were not intended to be dropped.
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Another variation of the high-visibility paint scheme is seen on this rather worn F6F-5K, a weathering challenge for an experienced modeler.
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The target drones could also be launched from carriers for live-fire exercises. Here is an F6F-5K of VU-3 aboard the USS Bon Homme Richard (CV-31).
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The Navy operated F6F-5K target drones until the 1960’s. This very clean example is seen set up for public display at an airshow.
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Several Hellcat drones were modified with wingtip pods in a variety of configurations. Some sources identify these as fuel tanks.
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Another variation on the high-visibility drone paint scheme, Orange Yellow with Insignia Red trim. The conversions retained the ability to be directly piloted.  (NASM, Rudy Allen Collection)
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A close-up of the unit insignia, a bee dodging bullets. The landing gear covers and cowling are trimmed in Insignia Red, but the landing gear legs (and likely the wheel wells) are in Orange Yellow. Note the prominent exhaust staining. (NASM, Rudy Allen Collection)

Hunter Killer Book Review

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Hunter Killer: Inside America’s Unmanned Air War

By LCOL T. Mark McCurley with Kevin Maurer

Hardcover in dustjacket, 368 pages, photographs

Published by Dutton, October 2015

Language: English

ISBN-10: 0525954430

ISBN-13: 978-0525954439

Dimensions: 6.25 x 1.13 x 9.25 inches

This book pulls back the curtain on America’s MQ-1 Predator “drone” program and the people who operate it.  LCOL McCurley was a U.S. Air Force instructor pilot who volunteered for transfer to the Predator program after the 9/11 attacks.  The transfer was not a normal request, the program was not a popular assignment within the USAF – “real” pilots flew fighters, and the Predator had become a dumping ground for officers who didn’t qualify for other assignments.

The term “drone”, though widely used in the press, is inaccurate.  A drone is an automatous vehicle, programmed to perform its mission without human intervention.  The U.S. Navy’s XM-47B is an example.   The MQ-1 Predator and its larger cousin, the MQ-9 Reaper, are more accurately described as Remotely Piloted Vehicles (RPV) or Remotely Piloted Aircraft (RPA), flown by a pilot and a sensor operator on the ground.  The crew is linked to the aircraft via satellite and can be physically located anywhere in the world.  RPVs operating over Afghanistan are routinely piloted by crews within the U.S.

One revelation for me was that it takes two separate crews to fly a mission – one where the aircraft is physically based to launch and recover the aircraft and one to fly the mission.   Many missions are flown in shifts due to the duration.  The crews operate under similar rules of engagement as any other U.S. unit.  Strike missions which eliminate high-value terrorist targets grab the headlines, but these are usually supported by weeks of routine 24/7 surveillance missions to establish the target’s patterns and minimize collateral damage.

The book is written from the first-person perspective and follows LCOL McCurley’s career in the RPV community.  It is an interesting insight into one of the USAF’s most-used platforms, and corrects many popular misconceptions.  It is an enjoyable read and an engaging story which I can recommend.

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Platz Northrop Grumman X-47B Drone in 1/72 Scale

The US media likes to run stories about “drones”, but they are almost always talking about a Remotely Piloted Vehicle (RPV) instead.  The Northrop Grumman X-47B is a true drone, it can be programmed to fly a mission and return.  It looks like something from a sci-fi movie but it’s real.  The prototypes passed their carrier qualifications easily and exceeded expectations, but the type was not adopted for service.  At least it was not adopted by the U.S. Navy, both the Russians and the Chinese have either reverse engineered or stolen the plans to make copies of their own.

Platz has released a kit in The One True Scale, and I just had to build it.  This is an excellent kit, well engineered and goes together without any surprises.  Not complicated at all, it is an easy build and a nice addition to the display case.

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The Kettering Aerial Torpedo

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Precision guided munitions have become a staple of modern aerial warfare.  Cruise missiles are high-tech vehicles which can fly hundreds of miles and hit their targets with pin-point accuracy.  While the common perception is that these are recent developments, the roots of these weapons go all the way back to the First World War.  One of the first “cruise missiles” was the Kettering Aerial Torpedo, designed by the famous American inventor Charles F. Kettering in 1917.
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Kettering’s reputation as an engineer lead to a request from the U.S. Army for a flying bomb with a 40 mile range.  Orville Wright was the aerodynamics consultant, Elmer Sperry designed the controls.  The “Bug”, as the design was to become known, was produced by the Dayton-Wright Company of Dayton, Ohio, which also produced DH-4s and Standard SJ-1 trainers.  Film here:  https://www.youtube.com/watch?v=gNO84yh2ZxY
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The Bug was powered by a Ford De Palma four cylinder engine rated at 40 HP.  Flight speed was a modest 50 miles per hour (80 kph).  Kettering exceeded the design requirement with a range of 75 miles (119 km).  Payload was 180 pounds (82 kg) of explosives.  Each Bug cost $400.
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The Aerial Torpedo was guided by a bearing and range system.  Bearing was maintained by a simple gyroscope.  Range was determined by calculating the number of engine revolutions required to cover the distance to the target, allowing for wind.  When the set point was reached, the engine was shut off and the wings were released, turning the Bug into a bomb.
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The Bug was launched using a wheeled cradle which rolled on a set of rails.  The rails were portable, and could be quickly erected in the field.  The launch dolly fell away from the aircraft upon take off.
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Wingspan of the Bug was 15 feet (4.6 m), length was 12 feet 6 inches (3.8 m).  Total weight was 530 pounds (241 kg).
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The Bugs were first flight tested in October 1918.  Approximately fifty were produced before the war ended and the remaining units were canceled.  The Army continued to test the Bug into the early 1920s.  Army film of 1919 testing here: https://www.youtube.com/watch?v=LQAi0_lN4FQ
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No original Kettering Aerial Torpedos exist today.  However, a reproduction is on display at the National Museum of the United States Air Force in Dayton, Ohio.

Interstate TDR US Navy Assault Drone

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The Interstate TDR was an unmanned “assault drone” developed for the U.S. Navy during World War II.  Like the parallel TDN drone, the TDR was designed to carry an aerial torpedo or a 2,000 pound bomb, the ordnance could either be dropped conventionally or carried directly to the target by the drone.  Here is an early TDR in flight carrying a torpedo.  Markings are standard for early 1942.
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Although it was equipped with a conventional cockpit for ferrying and testing, the drone was designed to be piloted by a remote operator flying in a TBM Avenger.  The operator controlled the drone using a television camera mounted in the nose.  The drone was gyro stabilized and carried a radar altimeter.  Effective range of the electronics was eight miles.
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The aircraft was constructed of non-strategic materials.  The airframe was made of steel tube by the Schwinn Bicycle Company.  The outer skin was formed plywood fabricated by Wurlitzer Musical Instrument Company.
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The production TDR-1 was powered by two Lycoming O-435 engines of 230 hp each giving a top speed of 140 mph.  450 hp Wright R-975 radial engines were also tested on the XTD3R-1 version shown here.  Three prototypes of this version were produced.
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The drones were deployed to the Pacific with Special Air Task Group One (STAG-1).  On 30JUL44 they were tested in the Solomon Islands under operational conditions against a beached Japanese freighter, the Yamazuki Maru at Cape Esperance, Guadalcanal.  Video of these tests can be seen here:  https://www.youtube.com/watch?v=CwS669Ipgwc
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The Interstate TDRs saw operational use in the Bougainville area and Rabaul where they were used against Japanese shipping and ground targets.  Of the 50 drones used in combat, 31 hit their intended targets.  The Japanese assumed these were manned aircraft and American pilots were deliberately crashing into their targets.
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STAG-1 used TDRs in combat from 27SEP44 to 27OCT44. While somewhat successful, the drones were still experiencing technical difficulties and the decision was made to terminate the program in favor of more conventional aircraft.   A total of 189 were produced.
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One Interstate TDR has been restored and is on display at the National Naval Aviation Museum at Pensacola Florida.

U.S. Naval Aircraft Factory TDN-1 Assault Drone

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During the Second World War the U.S. Navy issued a specification for an “assault drone”.  This was a secret project at the time, and remains largely unknown today.  The aircraft were built with an option for manned flight, but for operational use they were intended to be piloted remotely by a controller in an Avenger torpedo bomber or a PB4Y patrol bomber.
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By the early 1940s television technology had progressed to the point where it was feasible for use as a guidance system.  The aircraft also featured a radar altimeter.  Payload would consist of a 2,000 pound bomb load or a torpedo.  The operator could drop the payload in a conventional manner or crash the drone into the target.  Range of the guidance system was eight miles.
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The TDN-1 was designed to be simple to produce and to use non-strategic materials wherever possible.  The airframe was made of wood, and was powered by two 250 hp Lycoming 0-435-2 engines.  Wingspan was 45 feet with a length of 37 feet.  Brunswick, of bowling ball fame, produced the final 30 units of the 100 total production units built.
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The USS Sable (IX-81) was selected for the first carrier trials of the TDN drone.  The Sable was the former Greater Buffalo, a Great Lakes passenger steamer.  She was purchased by the Navy and equipped with a flight deck for the purpose of training Naval Aviators in carrier landings and take offs.  She and her sister ship, USS Wolverine (IX-64) were unique in having side-wheel propulsion.  They operated exclusively in the safety of the Great Lakes, training carrier aviators throughout the war.
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Three drones were hoisted aboard Sable from a barge at Traverse City, Michigan.  This would be the first time drones would be launched from a U.S. aircraft carrier, although the British had launched their first drones in 1937 from HMS Pegasus.
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Here are two drones secured to Sable’s flight deck.  The landing gear could be jettisoned after launch.  The weapons bay under the fuselage is clearly visible.  The television camera is located in the nose.
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This is one of the TDNs during her launch.  Note the empty cockpit.  For operational missions the windscreen and headrest would be removed and a fairing was installed over the cockpit opening.
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Sable launched the TDNs while steaming astern – note the canvas LSO platform screen to the left, the arresting wires on the flight deck, and the smoke from her coal-fired boilers drifting over her bow.  The day shape of two black balls hoisted above her island signal “not under command” which usually indicates a steering casualty.  In this case it may be intended to encourage other mariners to give the ship a wide berth.
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A rather steep launch!  Note the Grumman Duck in the background.  These tests were conducted on 10 August 1943.  Video of TDN tests can be seen here:  https://www.youtube.com/watch?v=-MzxIkr5JO0
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The launch of the second aircraft was not successful.  It stalled just after getting airborne and crashed into Lake Michigan.  This picture captures it just before impact.
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Testing included dropping inert bombs against a towed target sled.  Here two bombs are seen just after release, with the Grumman Duck again in the background.
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In this case the bombs fell just short of the target.
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The TDN was also tested against a stationary target.  In this case the aircraft carried the ordinance directly to the target, a precursor to the television-guided missiles of today.
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A hit!  Even though these tests validated the concept, the TDN was never used operationally.  The USN did field a similar competing design, the TDR, which I will cover in a future post.