Flying High This Past Week: 5 April-12 April

A continued thank you to all my readers and visitors with a special shout out to those who have added comments. When I first started this blog in 2009, the articles were really just short paragraphs on some part of aviation history I had come across in my reading that I wanted to share. Those posts were daily- a trip through the archives shows that to be the case- but as my family grew, there was less time to do daily posts, so I shifted over to more detailed articles that were posted every several days which is the current format. I have been considering adding shorter articles that would be on a more frequent basis or as a filler in between the five day interval of my longer articles. I certainly don't think it will be daily, but I'd like to have more frequent additions to the blog that at least dovetail with my current work and family obligations. We'll see, stay tuned for what I come up with. In the meantime, my more in-depth articles will continue to be posted here every five days. Without further ado, here's what's been getting a lot of hits in the past week here at TAILS THROUGH TIME:

• The Development of the Boeing Flying Boom: Quite obviously the most recent article usually tops our weekly round up and my most recent posting on how Boeing came up with the flying boom for aerial refueling certainly continues that trend. What I found most fascinating out of my reading for that posting was not just Boeing's process for determining the best positioning for aerial refueling, but that at one point Boeing considered for commercial jetliners as well.  
•  The Early History of the Air Line Pilots Association, ALPA: The previous article to the one on the Boeing flying boom still continues to get plenty of hits! The early history of Northwest Airlines is weaved into the early history of ALPA as the founder of the union, Dave Behncke, was Northwest's first pilot and flew its first passengers in 1927. The early history of ALPA gives us a good look at the state of the airline industry in the 1920s which was just on the cusp of making the leap into greater technologies led off by the Boeing 247 and Douglas DC-3. Despite the landmark in aviation history those aircraft were, flying for many professional pilots was still a hazardous profession in the years prior and many airline heads of the day tried to do what they could to stamp out ALPA in its early days. Fortunately a strike at a small airline that ran between St. Louis and Chicago thrust ALPA into the national spotlight and won it friends in high places.
• Vought's Not-So-Fearsome F6U Pirate: The Pirate was the first of setbacks that put Vought on the ropes as a fighter manufacturer for the US Navy. A series of misfortunes, the significant of which was its weak Westinghouse J34 engine, hit the program and by the time the F6U was ready for service, it was quickly overshadowed by superior aircraft like the McDonnell F2H Banshee and the Grumman F9F Panther. Some believe Vought over-compensated for the failures of the F6U Pirate with its next fighter, the F7U Cutlass. But they most certainly hit it out of the park with their third try that resulted in the F8U Crusader. 
• The A-6E TRAM: Making the Grumman Intruder More Lethal: The A-6E was the first major design upgrade of the Intruder over the A-6A that was introduced into combat in Vietnam. Many of the advances of the A-6E were in the miniaturization of its electronics and that created an opportunity to utilize the space created to add full all-weather/night attack capability in the form of TRAM- Target Recognition Attack Multi-Sensor.
• Lockheed's Own L-1000 Jet Engine: Believe it or not in the waning days of the Second World War, Lockheed was developing its own jet engine that, when compared with the current state of the art in jet turbines of the day, was quite advanced. The L-1000 would have had the service designation J37 had it been launched into production in 1947. 

The next article goes up later tonight, it will cover the origins and history of the barrier airborne early warning patrols over the Pacific and Atlantic that extended out the US radar fence from the continental United States to try and provide as much lead time as possible for a Russian bomber attack. Stay tuned! 

The Grumman A-6E TRAM: Making the Intruder More Lethal

The patch worn by A-6 Intruder crews. Note the radar and TRAM sensor symbolism

The main variant of the Grumman A-6 Intruder to fight in the Vietnam War was the first production version, the A-6A. The next two variants, the defense-suppression A-6B and the night attack-optimized A-6C, were just modifications of the basic A-6A variant and both the B and C versions served in only small numbers given their specialized roles. The next variant was actually the tanker version, the KA-6D. With the experience of combat, the Navy went ahead with the A-6E variant in 1968 which improved upon the deficiencies of the A-6A and replaced many of the 1950s-era systems with more modern equipment. With combat experience in the skies of Southeast Asia and over ten years of technological advancements, the A-6E was a major upgrade in capability, reliability and maintainability over the A-6A, with newer engines, a digital nav/attack system, a single multi-mode radar (the A-6A had two radars, which is why the Intruder had such a portly nose), and built-in test equipment that allowed the bombardier/navigator (B/N) to test the avionics before takeoff. On 22 September 1972, VA-85 "Black Falcons" embarked aboard the USS Forrestal were the first unit to take the new A-6E on an operational cruise. 

However, the navigation system of the new A-6E proved to be a weak spot and a few short years after the A-6E deployed with the fleet, CAINS (Carrier Airborne Inertial Navigation System) was added to the Intruder. Using the Litton AN/ASN-92 which was the same INS system used on the Grumman F-14 Tomcat and Lockheed S-3 Viking, an Intruder B/N literally plugged the aircraft's INS into the aircraft carrier's navigation systems to get a quick and very accurate initial fix before departing on a mission. But the most dramatic improvement to the capabilities of the Intruder came about at the same time as CAINS. At the time, there were a number of Intruder combat veterans assigned to the Office of the Chief of Naval Operations (OpNav) and with the Naval Air Systems Command. They spent their time getting upgrades and improvements pushed out to the Intruder fleet like CAINS.

A-6C TRIM. Note the prominent ventral gondola for the sensor.

One of the officers, Lieutenant Commander Lyle Bull, was working in the Aircraft Requirements Directorate of OpNav and decided to see what he could do to make the Intruder a full-capability all-weather/night attack aircraft that they had always dreamed about in Vietnam. During the war twelve A-6As were converted into the A-6C which had a large ventral gondola that housed the TRIM (Trails/Roads Interdiction Multi-Sensor) unit that had a FLIR and low-light TV (LLTV) unit for night attack missions over the Ho Chi Minh Trail. Large and aerodynamically bulky, TRIM also suffered from the relatively primitive state of the art in sensor technology at the time. Bull decided that TRIM was a good starting point for an improved system for the A-6E. This improved system became TRAM- Target Recognition Attack Multi-Sensor. In his position with OpNav, Bull had seen the state of the art in infrared technology and made the astute observation that there was space in the Intruder for an internal installation- because, as he put it, "Pods and sailors are not compatible". In the A-6A there was a separate search radar and a track radar in the portly nose- with the A-6E, a new Norden unit combined the functions into one radar and there was now space where the track radar used to be in the lower portion of the nose section. Bull had figured out that a 400-pound installation would fit perfectly into the space. 

In briefing his superiors on what TRAM could do for the A-6E, he pointed out that unlike TRIM which could only search and identify targets, TRAM would also incorporate an internal laser designator to mark targets for the new generation of laser guided bombs under development. Combined with the advances in sensor technology, an A-6E TRAM had a drastically improved bombing accuracy with miss distances of less than 10 feet, while today routine, such accuracy was stunning in the 1970s. However, in the lean funding environment following Vietnam, money for the R&D for TRAM had to be raided from other Naval Air Systems Command programs. Bull's superior, Rear Admiral Donald Davis, authorized $15 million in initial funding with the warning that the funding came from other programs which mean Bull wouldn't be liked- "They'll be after your ass, so watch yourself", he warned. 

A-6E TRAM prototype. Note the compactness of the installation.

Both Hughes and Texas Instruments agreed to develop competing designs for TRAM and Grumman readily agreed to handle testing and integration. Both systems were broadly similar differing in sensor details. TI had the advantage having developed the TRIM sensor during Vietnam- however, Hughes' design proved to better in testing and it was selected for the TRAM contract. As part of the TRAM integration, Grumman took the opportunity to upgrade the radar so it was better integrated with the TRAM sensor along with a new intertial navigation system. TRAM B/Ns would remark on the ease and simplicity of operating the laser designator. 

The A-6E TRAM prototype made its first flight at Grumman's Calverton facility on Long Island on 22 March 1974. With only a year of systems integration testing, Bull's system proved to be winner and the Navy began to procure TRAM units for the A-6E fleet. The first production A-6E TRAM flew on 29 November 1975 with VA-42 "Green Pawns" at NAS Oceana getting the first examples on 1 December 1975. Combined with CAINS, by the early 1980s the entire A-6E fleet was flying the most lethal Intruder variant yet and by that time, a Direction and Ranging Set (DRS) and Airborne Moving Target Indicator (AMTI) were added to the aircraft. This all made the A-6E TRAM Intruder the most accurate all-weather attack aircraft in the fleet if not all of the US forces. It would culminate with the A-6E TRAM being responsible for 85 percent of all the laser designations and LGB drops during Desert Storm. 

Source: Intruder: The Operational History of Grumman's A-6 by Mark Morgan & Rick Morgan. Schiffer Publishing, 2004, p131-133.

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.

The US Marine Corps had initially required the Grumman A-6 Intruder to meet an STOL requirement to take off in 1500 feet over a 50 foot obstacle. To accomplish this, the first seven A-6 Intruders had tilting tailpipes in which the exhaust of the twin J52 engines was vectored downward 23 degrees on takeoff and landing. There was a knurled knob on the outboard throttle that the pilot used to activate the feature. During testing, the Navy evaluation team set out to see if the feature worked as advertised and found the tilting tailpipes only marginally effective in meeting the USMC requirements- in fact, in many configurations the approach speeds were actually lower than they had been in propeller-driven aircraft.

The Navy team recommended deleting the feature at a cost savings of $25,000 per aircraft. After some back and forth arguing between the Marines and the Navy, the tailpipes and the associated actuation mechanisms were deleted beginning with aircraft number 8.

Source: Intruder: The Operational History of Grumman's A-6 by Mark Morgan and Rick Morgan. Schiffer Publishing, 2004, p16-17.