Flying High This Past Week: 22 February-1 March

So here's what's been getting a lot of page views this past week here at TAILS THROUGH TIME:

• The Boeing PBB Sea Ranger: The Best Flying Boat at the Worst Possible Time: Quite naturally the most recent aviation history article for this blog is going to lead things off on this installment of "Flying High This Past Week". One of the most fascinating areas of aviation history for me are those aircraft that either never went into production like the Sea Ranger or those that never left the drawing boards like the Focke Wulf Ta 183 "Huckebein". Look for more articles in the future from me that cover either unbuilt aircraft designs or aircraft that never went into production. What are often aviation dead-ends often leave a legacy for future designs. In the case of the Boeing PBB Sea Ranger, it left an unexpected legacy with Boeing that still plays a big part of the company today. 
• Tactics Over Technology: The Thach Weave: There's no argument that first six months of the Second World War in the Pacific that the Japanese Mitsubishi A6M Zero was ascendant as one of the aircraft apex predators of the skies. The Battle of Midway wasn't just a turning point in the Pacific War but it also represented a turning point in the fortunes of the Zero even though the stubby Grumman F4F Wildcat was still the main fleet fighter of the Navy and definitely not in the same class as the Zero. At Midway, the skipper of VF-3, Lt. Commander Jimmy Thach, instituted a new tactical maneuver called the "Thach Weave" that gave Wildcat pilots a fighting chance against the Zero.
• The Most Ambitious UAV Ever: Quartz/AARS: In the 1980s over $1 billion was spent on a stealthy UAV called the Advanced Aerial Reconnaissance System which was code named Quartz. It was a flying wing UAV that would penetrate Soviet airspace in times of war and search for the road and rail mobile ICBMs of the Soviet Strategic Rocket Forces. Boeing won the contract for the AARS over Lockheed but in 1992, Quartz was canceled, but it's believed the work that went into the design may bear fruit with a next-generation bomber to succeed the B-2A Spirit should the joint Lockheed/Boeing team be selected over Northrop Grumman. 
• The Ultimate Superfortress: The B/RB-54: This was the ultimate evolution in the Superfortress design lineage as a longer legged, faster, and even bigger version of the B-50 Superfortress which was itself quite an improvement over the wartime-era B-29. While it never flew let alone enter production as it came on the scene just as jet aircraft like the B-47 Stratojet were entering the picture, it did leave the drawing board. The B/RB-54 prototype was 75% complete when the program was canceled with its funding shifted to the Stratojet program. 
• One Powerful Helicopter Gunship: The ACH-74A "Guns A-Go-Go": Only four of these gunship Chinooks were built and flown into combat in Vietnam 1966-1968. To the best of my knowledge, these beast machines are the only helicopter gunships to ever go into combat with an unobstructed 360-degree field of fire.

That's all for this installment of "Flying High This Past Week". Stay tuned to TAILS THROUGH TIME- there will be a new aviation history article posted here every five days. The next one will be going up on 3 March. And don't forget last week's installment of "Flying High This Past Week"!

Operation MARHUK: The Combat Debut of the Marine's AH-1J SeaCobra

Marine SeaCobras took a beating operating at sea

The first US Marine Corps AH-1 Cobra gunships in action were actually AH-1Gs which were ordered by the Marines in 1967- having closely watched the Army development of the Cobra gunship, 72 helicopters were requested for one helicopter attack squadron in each of its three Marine Air Wings. Despite having the approval of the Secretary of the Navy, Defense Secretary McNamara overruled the decision and only allowed the Marines to order 38 of the single-engined AH-1G variant. With the first Marine AH-1Gs going into action in Vietnam in April 1969, reports from the field couldn't have been more salutatory in the effectiveness of the Cobra gunship. Based on that initial experience, the Marines wanted a more powerful Cobra- one with twin engines, Marine avionics, a rotor brake for shipboard operations and a harder-hitting gun in the undernose turret. After overcoming the resistance of an obstinate Secretary McNamara, the AH-1J SeaCobra went into production with the first examples undergoing combat evaluation in South Vietnam in February 1971. With the onset of the Easter invasion by North Vietnam of the south and the American response, Operation Linebacker, the first Marine helicopter attack squadron, HMA-369 based in Okinawa, was called upon shortly after its establishment to conduct offensive operations against North Vietnam. 

The USMC had the AH-1J built from the start to operate from ships

At the time, Army Cobra gunship were operating in South Vietnam against the invasion thrusts of the North Vietnamese Army. Despite having just received its new AH-1J SeaCobras, Admiral John McCain, Jr, head of the US Pacific Command, wanted to make sure that the blockade of North Vietnam was complete. Even though carrier aircraft had sown mines closing Haiphong Harbor, the North's main port, the North Vietnamese had resorted to having Chinese and Soviet cargo ships anchor offshore various locations and cargo would be offloaded into smaller sampans for transfer to the shore. This way the mined sea lanes could be avoided. Because fixed wing carrier aircraft were urgently needed for Operation Linebacker attacks on North Vietnam, it was decided that the AH-1J SeaCobra would be ideal for the role of maritime interdiction off the coast of North Vietnam. In the entire Pacific theatre, only HMA-369 in Okinawa had suitable helicopters for the job and Operation MARHUK (Marine Hunter-Killer) was born. It would be the Bell AH-1J SeaCobra's baptism of fire and off the coast of the heavily defended North Vietnamese coast, no less. 

HMA-369's "Marhuker" patch

 HMA-369 originally wanted a helicopter carrier to be based on for Operation MARHUK, but the Navy's LPHs were heavily committed else where and the 18 officers, 99 men and seven AH-1J SeaCobras of HMA-369 that were ready to deploy in June 1972 were shoehorned into the amphibious transport ship USS Denver (LPD-9). Marine brass give the squadron officers a blank check to do what ever was necessary to get HMA-369 to the war zone and the nickname "Marhukers" was given to the officers who improvised and bent and possibly broke many rules to make their SeaCobras combat ready. Even 5-inch Zuni rockets were procured, a weapon that had not yet been cleared for use from the AH-1J. The ship and its escorts would be positioned near the Hong La anchorage further south down the coast from Haiphong. Here Chinese and Soviet merchant ships anchored offshore and North Vietnamese sampans offloaded cargo offshore to bring into Hong La. Since the rules of engagement forbade hitting the merchant ships, the SeaCobras stayed at least 500 yards away from the ships and remained overwater the whole time as the North Vietnamese had heavy AAA guns on  the shoreline. The SeaCobras operated in pairs and would sink the sampans with their Zuni rockets and 20mm undernose cannon. The pilots were also trained to call in naval gunfire and air strikes while the gunners in front seats of the AH-1Js focused on the sampans. After several weeks, the shore-based heavy AAA guns learned not to fire on the SeaCobras thanks to the naval fire support and air strikes the pilots would call in. 

In August 1972 HMA-369 moved to the USS Cleveland (LPD 7) and then again to the USS Dubuque (LPD 8). Over the course of Operation MARHUK, the AH-1J SeaCobras were called on to provide air cover for downed aviators in the North as well as functioning as forward air controllers for Navy strike aircraft. Missions ranged from 80 miles north of the DMZ to as far north as 80 miles south of Hanoi inland! When Operation MARHUK ended on 26 January 1973 with the end of Operation Linebacker II, nearly 1,000 sorties had been flown with 123 sampans sunk, further straining the logistics of North Vietnam that eventually drove them to the bargaining table. It was quite a stunning debut for the AH-1J SeaCobra. 

Source: Helicopter Gunships: Deadly Combat Weapon Systems by Wayne Mutza. Specialty Press, 2010, p72-76.

One Powerful Helicopter Gunship- the ACH-47A "Guns A-Go-Go"

The weapons loadout of the ACH-47A Chinook gunship

After years of experimentation with armed helicopters, the US Army finally sent armed Bell UH-1B Huey gunships into combat in October 1962 with the rocket/gun armed Hueys acting as escort for Piasecki CH-21 Shawnee transports out of Tan Son Nhut Air Base in Saigon. Despite the growing success of the armed Hueys in the growing conflict in Vietnam, the Army sought a helicopter that offered even more firepower to replace the Huey gunships. Initial evaluations began in 1964 and even despite the selection of the Bell AH-1 Cobra (the world's first dedicated helicopter gunship design) in 1966, the general staff wanted something with even more firepower than the Cobra gunship as it was felt to only be an interim design pending what the Army felt was the ultimate gunship, the Lockheed AH-56 Cheyenne. While the Army pushed for a large gunship based on experiences in Vietnam, it found itself running into opposition from the USAF which felt its traditional domain of fixed wing close-air support being infringed upon by more capable helicopter gunships. Regardless, combat experience proved to be a powerful argument and the existing Hueys were felt in certain situations lacking in firepower. With the Army due to deploy the Boeing Vertol CH-47 Chinook transport helicopter to Southeast Asia in November 1965, Boeing Vertol submitted a formal proposal to the Army to modify eleven Chinooks into heavy gunships and on 2 July 1965 the first test Chinook was diverted from the production line in Philadelphia for conversion into the prototype ACH-47A. 

The heavy lift capability offered by the twin turbine-powered Chinook allowed for many choices of possible armament systems, weapons loads, and self-protection. No concept was considered too outlandish as even manned turrets and stub wings for mounting weapons were considered. The eventual weapons fit of the ACH-47A became the XM5 40mm grenade launcher in a turret in the nose fed by a flexible belt that ran through the cockpit to the forward cabin where a container holding 500 rounds was located; a 30-inch stub wing on each side of the forward sponsons that at the end mounted an M24A1 20mm cannon, each fed by an 800-round container in the middle cabin; under each stub wing was a pylon that could mount either a 19-round 2.75-inch rocket launcher or a pod-mounted 7.62mm rotary Minigun. In addition to these permanently mounted systems, there were five crew-operated 50-caliber gun stations- forward right side, forward left side, right and left waist, and cargo ramp. The waist and forward stations had enlarged openings to allow a wider field of fire and the top half of the cargo ramp was removed to expand the rearward field of fire. Each 50-caliber gun had its own 1,000 round supply. With the five gunner stations, the ACH-47A would be the only helicopter gunship to fly into combat with a full 360-degree field of fire. 

Two ACH-47As during the flight test program. Note the gloss paint scheme.

Despite the removal of items not needed for the gunship mission (items like the troop seats, cargo handling gear, even soundproofing), over 2,500 lbs went back into the ACH-47A for armor plating for the crew, rotor pylons, and vital systems. The standard Lycoming T55 turboshaft engines were uprated to 2,850 hp each compared to 2,200 hp for the standard CH-47A transport. This meant that a fully-loaded ACH-47A had the same performance as a operationally-loaded CH-47A. The first ACH-47A made its maiden flight at the Boeing Vertol plant in Philadelphia on 6 November 1965, only four months after the work began! After flight testing, the first ACH-47A was delivered to the Army for weapons trials at Aberdeen Proving Ground in Maryland and then to Fort Benning, Georgia for operational training in March 1966. At Fort Benning, the 53rd Aviation Detachment, Field Evaluation (Provisional) was formed for the training and operation of the ACH-47A and in April 1966 three more ACH-47As arrived, but due to budgetary constraints, only four ACH-47As could be built and delivered. The first one, 64-13145, was initially named "Crazy 8" but was renamed "Cost of Living". 64-12149 became "Easy Money", 64-13151 was named "Stump Jumper" and the last one, 64-13154, was named "Birth Control". The last three shipped out to Vietnam in May 1966 while "Cost of Living" remained at Edwards AFB for more testing. 

"Easy Money" resting between missions at An Khe

The six-month period of operational testing would be split between Vung Tau in the southern coast one hour downriver from Saigon and at An Khe in the centeral highlands of South Vietnam. At Vung Tau the ACH-47As would operate not just with American units fighting the Viet Cong but also the Royal Australian Task Force. At An Khe, the ACH-47As operated with the 1st Cavalry Division. At both locations the 53rd Aviation Detachment remained the operator and acquired the nickname "Guns A-Go-Go" as a result of the heavy firepower of the Chinook gunships. Troops in contact with enemy forces favored the ACH-47As for their firepower and 360-degree field of fire. On 5 August 1966, "Stump Jumper" was destroyed in a freak accident at Vung Tau when it collided while taxiing with a transport CH-47A. The ACH-47A that was still at Edwards AFB "Cost of Living" conducting advanced testing was then prepared for deployment to replace the destroyed "Stump Jumper". One of the missions assigned exclusively to the ACH-47As was to go into an area that had just been carpet bombed by a B-52 Arc Light strike and finish off any enemy positions that survived the bombing. It was considered heavily armed enough and heavily protected enough to be able to finish off the job left by an Arc Light strike!

At the end of the test period in December 1966, "Cost of Living" arrived in Vietnam and the 53rd was redesignated the 1st Aviation Detachment (Provisional) attached to the 1st Cavalry Division at An Khe. Enemy forces became reluctant to fire upon any Chinook after a while because at a distance, the ACH-47A was hard to distinguish from a standard CH-47A transport Chinook. On 5 May 1967 while on an attack run, a retention pin on the stub wing of "Cost of Living" came loose and allowed the gun to elevate and fire into the forward rotors, causing the gunship to crash with the loss of all onboard. The two remaining ACH-47As, "Easy Money" and "Birth Control", however, kept flying as the need for their firepower was highly desired by troops in contact. The end of the Chinook gunship program came during the 1968 Tet Offensive at the Battle of Hue. On 22 February 1968, "Birth Control" was forced down due to multiple hits after an attack run in low ceiling conditions. Autorotating into a rice paddy near the walls of the Citadel in the ancient city of Hue, the crew started taking heavy fire from the Citadel area. "Easy Money" made several attempts to land and rescue the crew of "Birth Control", but the ground fire was too intense. "Easy Money" finally landed, but overshot and found itself between the Citadel and "Birth Control". Two UH-1 Huey gunships unleashed 76 2.75-inch rockets into the source of the enemy fire, allowing "Easy Money" to struggle airborne with the crew from "Birth Control". Before the downed ACH-47A could be recovered, it was destroyed by enemy mortars. Since the tactics called for the ACH-47As to operate in pairs, "Easy Money" never flew into combat again as no Chinooks were available for conversion as every one was needed for transport duties in Vietnam. With the number of Bell AH-1 Cobra gunships increasing in Vietnam, "Easy Money" sat out the rest of the war as a maintenance trainer at Vung Tau.

The logo of "Guns A-Go-Go

"Easy Money" ended up in the boneyard at Savannah Army Depot. Boeing had evaluated the airframe for possible conversion to the prototype CH-47D, but it was found to be too corroded to be of any use. It was moved to Fort Eustis where it was used as a sheet metal trainer before it was moved to the base scrapyard. It's historical identity was discovered in 1997 when the "Easy Money" name was uncovered under layers of paint. The aircraft was duly restored and is now on display at Redstone Arsenal, in Alabama. In 2006, the 160th Special Operations Aviation Regiment "Nightstalkers" at Fort Campbell, Kentucky, set up a new battalion at Fort Lewis, Washington, to serve special operations units based on the West Coast for operations in the Pacific. Equipped with the advanced MH-47G Chinook, the unit approached the veterans of the 53rd "Guns A-Go-Go" for permission to resurrect the unit designation, patch, and "Guns A-Go-Go" call sign- which of course was agreed to with enthusiasm!

I highly recommend you visit a tribute website to the ACH-47A and "Guns A-Go-Go"!

Source: Helicopter Gunships: Deadly Combat Weapon Systems by Wayne Mutza. Specialty Press, 2010, p41-55.

The Complicated Path to Nighttime Interdiction in Vietnam

Project Black Spot NC-123K

When it was realized that interdiction of the nighttime movement of supplies along the Ho Chi Minh Trail was the best way to stop the flow of materiel to the Vietcong in the South, the USAF in February 1966 established Operation Shed Light to pool together research efforts and various subprojects into improving the night fighting capabilities of the USAF in Vietnam. Projects Red Sea and Lonesome Tiger belonged to a series of experiments using Douglas AC-47s and Douglas B-26K Invaders equipped with FLIR. Tropic Moon I concerned the use of a low-light television camera (LLTV) to seek out targets at night. A Douglas A-1E Skyraider flew with the Tropic Moon I package, becoming the first aircraft to use a self-contained night attack system in combat.

Tropic Moon II was the modification of three Martin B-57 Canberras into night attack configuration and Tropic Moon III was a further development that involved the modification of 16 Martin B-57Gs with more sophisticated attack avionics.

Briteye was a new battlefield flare that could be used to illuminate the target area and that led to the BIAS (Battlefield Illumination Airborne System) that used 28 xenon arc lamps in a Fairchild C-123K's cargo compartment to produce daylight conditions in an area 2 miles wide from 12,000 feet. Also used on the Lockheed C-130 Hercules, unfortunately BIAS gave enemy anti-aircraft gunners a nice bright target at night.

Operation Shed Light identified the need that a night attack aircraft be completely self-contained and autonomous but had to be large enough to carry the heavy electronics of the day. Initial aircraft candidates were the McDonnell F-4 Phantom, Martin B-57 and Grumman OV-1 Mohawk. There were too few B-57s to spare, the F-4s were already heavily committed and the Air Force didn't want to stoke interservice rivalries by selecting the Army's OV-1 Mohawk. The General Dynamic F-111 was considered the most ideal, but at the time the aircraft wasn't yet operational so the study group next looked at the North American OV-10 Bronco, but it didn't have the load carrying capability.

The most ideal aircraft at the time was considered to the be the Navy's Grumman S-2 Tracker ASW aircraft- it already had a large weapons bay, it was twin-engined, could operate at low level as that was its natural regime when hunting submarines, and it also had good endurance and had a built-in search light. The aircraft was to have been designated the AS-2D and eventually the AS-2D had to be cancelled in 1968 due to difficulties with funding the modifications and problems in getting S-2 Trackers from the US Navy.

Desperate for a platform the Shed Light group turned to a low-level project initiated in 1965 called Project Black Spot which was to use a modified Fairchild C-123K as a self-contained night attack aircraft that instead of bombs or guns, dropped cluster submunitions from chutes in the fuselage. The first Black Spot aircraft, designated NC-123K, began evaluations at Eglin AFB in Florida in 1968 and after some initial trials in Korea to see if its night vision equipment could spot North Korean infiltration teams using boats, debuted in Vietnam operationally in November 1968.

Source: Gunships: The Story of Spooky, Shadow, Stinger and Spectre by Wayne Mutza. Specialty Press, 2009, p161-165.

By mid-1971, the Royal Laotian Air Force had thirteen AC-47 "Spooky" gunships on strength and were conducting approximately 50 missions per month in support of government ground units as well as the Hmong tribesmen in the highlands. Though superstitious, the Laotion gunship crews readily adopted the Spooky call sign but would not operate the AC-47s seven crew members as Buddhist tradition regarded the number seven as an unlucky number. As a result, RLAF AC-47s went into combat either with one man short (six crew) or one man extra (eight).

Source: Gunships: The Story of Spooky, Shadow, Stinger and Spectre by Wayne Mutza. Specialty Press, 2009, p183.