The Douglas F6D Missileer

The F6D Missileer's resemblance to the F3D Skyknight is apparent

In 1957 the US Navy issued a specification for carrier-based fleet defense fighter that could loiter for long periods of time at long distances from the carrier. In addition, the aircraft had to be able to engage enemy aircraft at 100 nautical miles with a powerful onboard radar and long-range air-to-air missiles. Under the assumption that enemy aircraft were to be destroyed at well beyond visual range, dogfighting capability was not necessary and the need for long endurance dictated a subsonic design. Six hours was the specified endurance for this fighter and in turn this meant a large fuel load. The complex radar systems planned called for a three-man crew, with the pilot and co-pilot on each side of the radar intercept officer, this way both of the flying crew man could share some of the same displays with the radar intercept officer (RIO). 

There were four components to 1957 concept for fleet air defense that would be issued to industry for submissions. The first, of course, was for the aircraft itself, which was awarded to Douglas Aircraft Company in 1959 for what was designated the F6D Missileer. But in addition, a contract was awarded to Westinghouse for the AN/APQ-81 radar that would be used by the F6D to track and engage enemy aircraft. The third component was a contract awarded to the Bendix Corporation for the large AAM-N-10 Eagle missile. What is little-known about the F6D program was the fourth component, for an advanced airborne early warning aircraft to search out targets for patrolling Missileers. This contract would go to Grumman Aircraft which resulted in the W2F Hawkeye (later redesignated E-2 Hawkeye) with its advanced AN/APS-125 radar which could scan an area 400 miles in diameter and cue several F6D Missileers. 

Overall configuration of the F6D Missileer

The F6D itself resembled a scaled-up version of the Douglas F3D Skyknight twin-seat all-weather/night fighter. The nose section was quite bulbous to house the Westinghouse AN/APQ-81 radar and the three man crew were seated side-by-side in a cockpit that resembled that of the Grumman A-6 Intruder. Two non-afterburning Pratt & Whitney TF30 turbofans were mounted on each side of the fuselage just under the unswept wings. At the time, the use of a turbofan engine in a combat aircraft was a new concept and the TF30 was selected for its fuel economy. Since the Missileer didn't have to be supersonic, there was no need for a heavy and fuel-hungry afterburner. 

The Westinghouse AN/APQ-81 radar would have been the most advanced radar of its day using pulsed-Doppler technology years before the first production pulse-Doppler radars would enter service. The radar had a maximum range against large aircraft of 120 miles and could track as many as eight targets at once. The radar could also send mid-course corrections to the Eagle missiles. 

Overall configuration of the AAM-N-10 Eagle missile

The Bendix AAM-N-10 Eagle was the first of the four components from the 1957 fleet defense concept to be awarded. A large solid rocket booster would boost the Eagle to Mach 3.5 after launch on a loft trajectory for maximum range. After the booster was jettisoned, the Eagle's own sustainer motor ignited and further accelerated the missile to Mach 4.5. The use of a loft trajectory gave the Eagle missile a range of 160 miles and on final approach to the target, the missile's own onboard radar system (based on the radar used on the Bomarc surface-to-air missile) switched on. The Eagle could be armed with either a conventional or nuclear warhead.

Despite the advanced nature of the technology used in the F6D Missileer program, many quarters in the Navy fundamentally opposed the concept, arguing that once the Missileer had fired its six Eagle missiles, it was left vulnerable and unable to defend itself as it lacked any other armament and its large subsonic size precluded any evasive maneuvers. Once firing its missiles, the Missileer faced a long return flight to the carrier to refuel and re-arm. In 1960, the building opposition within the US Navy won out and the F6D Missileer program was canceled along with the Westinghouse AN/APQ-81 radar and what was becoming an enormously complex AAM-N-10 Eagle missile. The cost of developing the missile itself was estimated to be more than the aircraft development cost. 

However, the development of the Grumman W2F/E-2 Hawkeye continued and the aircraft is still in production today, albeit with more advanced radar systems, and is perhaps sole remaining legacy of the ambitious, but flawed, F6D Missileer program. 

Source: American X & Y Planes: Volume 2; Experimental Aircraft Since 1945 (Crowood Aviation Series) by Kev Darling. The Crowood Press, 2010, p60-61. Photos: Wikipedia, various internet forums.

Two Paperclips and an Eraser Contribute to Victory in WW2

The first variants of the Navy's premier carrier-borne fighter of the first half of the Second World War, the Grumman F4F Wildcat, were hampered by one weakness even before they took off from their aircraft carriers- lacking a folding wing, the first versions of the Wildcat took up quite a bit of space on the carrier and, by extension, that limited the number of Wildcats that could carried aboard. Given combat losses that would inevitably occur, having as many aircraft on the carrier as possible conferred tactical advantages in battle. The current production version of the Wildcat at the time was the F4F-3. 

The most obvious answer would be hinge the wings' outer sections and folding them upward as was done on most carrier aircraft (even to this day). However, to Leroy Grumman and his engineering team, that wasn't an optimal answer as that increased the height of the stowed aircraft- if the wing could be folded in a way that didn't increase the height of the aircraft, then extra aircraft could be winched up and stowed up near the ceiling of the hangar deck. Grumman reasoned that the optimum geometry would be to somehow fold the wing back not unlike the way a bird folded its wings back along its body. Grumman drew upon his engineering intuition and reasoned that the wing had to rotate about a pivot point. He took a draftsman's eraser and two paperclips; he bent one end of the paperclips and began to stick them into the eraser. The eraser was the body of the Wildcat and the paperclips were the wings. By trying different angles, Grumman managed to figure out the angle needed to that when the clip was rotated, it folded back flat against the eraser. This was known in engineering parlance as a skewed axis. 

In the Wildcat, this axis was a pivot set into the wing root that pointed outward and backward at angle into the moving portion of the wing. As the wing rotated about this pivot, it folded back against fuselage, making the F4F a compact package- so compact, that six F4Fs with what Grumman called the "Sto-Wing" could fit into a deck or hangar space normally occupied by two F4Fs that had nonfolding wings. At first it was planned to use hydraulics to fold the wings, but it was found this added excessive weight, so the wings would have to be folded manually by the deck crew. A large master pin would lock the wing in position either extended or folded.

The Sto-Wing was immediately placed into the production line- with the current Wildcat model being the F4F-3, those with the Sto-Wing became the F4F-4. From a tactical standpoint, an aircraft carrier could now carry twice as many F4Fs as before with the wingspan of the Wildcat going from 39 feet to just over 14 feet folded. Deck handling improved as it was easier to move an F4F with the wings folded on a crowded flight deck or in a packed hangar deck. The Sto-Wing concept was applied as well to the TBF Avenger and the F4F Wildcat's successor, the F6F Hellcat. And it's seen today on carrier decks with the Northrop Grumman E-2 Hawkeye- since the E-2 had the dish-like radome above the fusleage, the wings couldn't be folded up and over each other as was done on other long-span carrier aircraft like the Lockheed S-2 Viking. So E-2 Hawkeye's wings use the Grumman Sto-Wing principle to fold back towards the tail.

Source: The Grumman Story by Richard Thruelsen. Praeger Publishers, 1976, p124-125.

The Drug-Busting Night Wolves of VAW-77

I had earlier featured US Navy E-2 Hawkeye squadron VAW-77 "Night Wolves" and the crucial role they played during the rescue efforts in New Orleans during Hurricane Katrina. It turns out that VAW-77 is a very unique squadron within the US Navy on several counts. Though a Reserve unit no different than many of the reserve air units of the different branches of the US military, VAW-77's primary mission is Counter-Illicit Trafficking (CIT) and as such, they are not required to operate from aircraft carriers and therefore its pilots do not have to go through carrier qualifications.

Eighty percent of the squadron's flight hours are devoted to CIT operations and when operating from several locations in the Caribbean and Latin America, fall under the jurisdiction of US Naval Forces Southern Command as part of the Joint Inter-Agency Task Force South (JIATF SOUTH). Deployments depend upon intelligence received from a variety of sources. During CIT missions, the E-2 is paired up with another air asset that acts as the "low bird" while the Hawkeye operates as the "high bird" cueing the "low bird" to targets of interest. In most circumstances, the "low bird" is a Navy P-3 Orion or a US Coast Guard HC-130 Hercules. Other times the "low bird" role may be filled by aircraft of cooperating nations in the Caribbean and Latin America. At times, the E-2 has to act in both roles, dropping down to low altitude to make visual contact, but this is done as little as possible as it's a less than ideal tactical arrangement.

In 2009, VAW-77 flew over 2,000 hours of CIT missions that aided in the seizure of 17.2 metric tons of cocaine and also assisted in the rescue of 15 individuals.

The other 20% of the squadron's flying time is devoted to Fleet Support and Homeland Defense. The Fleet Support mission usually entails area surveillance for the missile ranges of the Gulf of Mexico while Homeland Defense missions can include border surveillance and airborne control of air defense assets. In addition, VAW-77's E-2 Hawkeyes have been tasked with providing surveillance for Air Force One and range control during Space Shuttle and rocket launches from Kennedy Space Center/Cape Canaveral. When other E-2 squadrons have downtime between deployments, junior personnel are often sent to VAW-77 to gain experience and flight hours.

Source: Combat Aircraft Monthly, July 2010, Vol. 11, No. 7. "Drug Busting Night Wolves" by Ted Carlson, p26-31. 

In the early morning hours of 29 August 2005, Hurricane Katrina made landfall near New Orleans as a Category 4 storm. In addition to the widespread flooding and destruction, the storm also destroyed much of the area's communications infrastructure from cellular towers to air traffic control systems. As an integral part of Joint Task Force-Katrina (JTF-Katrina), the US military, civilian agencies, and those nations who came to assist needed airspace coordination with as many as 80 helicopters alone airborne throughout the area rescuing survivors and inbound relief flights and outbound evacuation flights.

Two Navy E-2 Hawkeye squadrons provided air traffic control and coordination as well as a detachment of P-3 AWACS aircraft from the US Customs Service. The two Hawkeye squadrons involved were the reserve unit VAW-77 "Nightwolves" (call sign WOLF) from NAS Atlanta and VAW-126 "Seahawks" (call signs SEAHAWK and CLOSEOUT) from Carrier Air Wing Three embarked on the USS Harry S Truman which was sailing in the Gulf of Mexico assisting with relief efforts. In addition, the US Customs P-3 AWACS (which use a similar radar system as the E-2) from their home base in Corpus Christi (call sign OMAHA) also assisted the Navy Hawkeyes.

The E-2's radar and extensive communications suite allowed the crews to monitor the airspace, assist in location of stranded survivors, direct rescues, air traffic control and even identify with the radar safe landing areas and locations of tall obstructions. The two squadrons adopted the same system used for directing close air support for the New Orleans environment, using a grid and keypad system overlaying the area to coordinate and direct rescue aircraft and deconflict the airspace much in the same way fighters and strike aircraft might be directed to targets. At times a single E-2 might be controlling as many as 80-90 helicopters operating over the metropolitan area.

The E-2 Hawkeye has a crew of five- two pilots up front and three NFOs (naval flight officers) in the back who provide the airborne control and communication. The center seat is usually occupied by the commander or combat information officer who directs the efforts of the two NFOs on each side. Many of the helicopter pilots involved in the relief preferred working with the E-2 Hawkeyes as the smaller number of crew aboard made decision-making quick compared to the larger platforms like the P-3 AWACs. All one of the NFOs would have to do to direct a rescue effort was to turn to his commander and ask for clearance.

Source: Flying the World's Greatest Aircraft: Superlative Military Machines from Sabre to Raptor, James Bennett, editor. Fall River Press, 2009, p81.

Some planes are like the Rodney Dangerfields of aviation- they just don't get any respect. If there's one plane that I think of in that regard, it has to be the Grumman E-2 Hawkeye. Development began on the Hawkeye in 1956 as a replacement of the Grumman WF/E-1 Tracer as the "eyes" of the carrier battle group. The first E-2A Hawkeyes entered fleet service in 1964 and were a quantum leap over the early E-1 Tracer. Since then, Grumman (and now Northrop Grumman) have made continual refinements to the E-2 Hawkeye's systems that while the external appearance of the aircraft hasn't changed significantly, the radar systems are far more advanced than what went to sea in 1964.

The latest version of the E-2 is the E-2D Advanced Hawkeye. While the distinctive eight bladed propellers on each engine are new, they're not unique to the E-2D Advanced Hawkeye as they have been retrofitted to current E-2Cs in the fleet. The heart of the changes to the E-2D are all internal, as have most of the significant changes to the Hawkeye over the years.

The needs for both overland/littoral as well as oceanic surveillance have resulted in the AN/APY-9 radar being a unique hybrid of an electronically-scanned unit inside the rotodome that also was mechanically scanned by rotating the entire unit as well. The radar couldn't be a true AESA (active electronically scanned array) due to weight and space limitations for a carrier-borne aircraft. The transmit and receive equipment for the new radar are located in the fuselage and connect to the antenna in the rotodome via a high power RF coupler. As a result, the rotodome can rotate and be locked down to focus on a specific threat sector as the Navy's primary requirement for the new system was for theater ballistic/cruise missile defense. The new radar compared to the AN/APS-145 of the E-2C has a staggering 300% increase in the volume of sky it can search.

Interestingly the data systems on the new version of the Hawkeye are based on commercial off-the shelf (COTS) technology with a fiber optic local area network (LAN) using commercial Ethernet standards and a mission computer running Linux. This was done to facilitate future upgrades which, in essence, could be done with the ease of computer infrastructure upgrades in the consumer world.

The external appearance of the E-2D Advanced Hawkeye is essentially unchanged from the current E-2C, but the aircraft is 1,500 lbs heavier and as a result, a white triangle is painted on the nose ("delta" for the E-2D) as a recognition for the carrier LSOs that the arresting gear has to be set for a higher weight than other E-2 versions.

When the last E-2D Advanced Hawkeye is delivered to the fleet in 2021, it will have been an astounding fifty-seven years since the Hawkeye first went to sea in 1964! Maybe it doesn't get a lot of the attention and glory that the fast jets of the carrier air wing gets, but what might end up being 70+ years of service sure as hell gets my respect!

Source: Air International, March 2010, Vol. 78, No. 3. "Twenty-First Century Hawkeye" by Dave Majumadar, p38-47.