26 February 2011

Genesis of the Predator UAV

Leading Systems' Amber UAV, grandfather of the Predator
In the mid-1970s, Abraham Karem, a designer of high-tech weaponry for the Israeli Defense Forces, emigrated to the United States but despite his credentials working with the Israeli military, found himself unable to get employment with any of the major American defense contractors. Karem had some innovative ideas for unmanned aerial vehicles (UAVs), so ended up starting his own company, Leading Systems, in the garage of his home in Irvine, California, to pursue his UAV concepts. In 1982, the Defense Advanced Research Projects Agency, DARPA, was providing seed money to small companies that offered innovative solutions to problems outlined by the US military. One such problem was a need for an advanced UAV that could provide reconnaissance imagery while having a long endurance but be both inexpensive and reliable. The classified DARPA program TEAL RAIN was established to study the technology for long-endurance UAVs. The problem at the time was that previous long endurance UAVs exemplified by the Boeing Condor as well as the Compass Cope program were large and prohibitively expensive. Two years after he founded Leading Systems, Abraham Karem secured seed money from DARPA to develop his concepts and in 1984, he received a contract to develop a classified reconnaissance UAV code-named Amber. While most competing companies adapted existing piston engines from snowmobiles and motorcycles for their designs, Karem used the DARPA seed money to hire engineers willing to design and build engines custom tailored for the Amber program. 

The first Amber UAV flew in 1986 (just two years after Karem got the DARPA contract!). Karem designed Amber to fold up and be fired from a standard torpedo tube- the US Navy was one of the backers of the Amber project- as a result, it had a slender fuselage with a parasol wing and an inverted-V tail with a pusher prop. Two types of Amber UAVs were planned- the "A" version had a pointed nose section carrying a warhead and was to be a low-cost cruise missile- approaching its target, the wing was to be jettisoned, hence the need for a parasol-type wing. The "B" version replaced the warhead section of the "A" version with a slightly bulged nose compartment that housed imaging sensors and datalinks to act as a reconnaissance UAV. The "B" version had a stalky retractable landing gear as well. The use of an inverted-V tail was to protect the pusher prop during landing and takeoff. By 1988, Amber had demonstrated a flight endurance of nearly 40 hours when competing companies were barely getting 12 hours out of their designs. Not only was Karem's design outflying its competitors, it was also proving to be immensely reliable as well. Thirteen Amber UAVs were built by 1990. 

In the same year that Amber was breaking records in 1988, Congress began to get impatient with the Pentagon's slow pace of UAV development. By 1990 the Pentagon was forced by Congressional mandate to consolidate the UAV research efforts of the different armed services into a single Joint Program Office (JPO). The JPO, however, wasn't budgeted any funds for research, which meant that only big defense contractors could stay in the running where internal corporate funding was plentiful. At the same time, and in its infinite wisdom, Congress banned DARPA from supporting UAV projects outside of the jurisdiction of the Pentagon JPO and as a result, Leading Systems' funding dried up overnight and Amber had to be canceled despite its achievements. 

Leading Systems/General Atomics Gnat 750
To try and stay afloat, Abraham Karem and his small team at Leading Systems developed a UAV based on Amber that was less-complex and used a standard Rotax piston engine for propulsion. This UAV was named the Gnat 750. Since the Gnat was planned for the export market, it was larger and didn't have as many of the advanced features of Amber, but it retained the overall layout with the difference that the wing was now directly attached to the fuselage instead of high-mounted on a pylon. The inverted-V tail was still there as well as a pusher prop and the stalky retractable undercarriage. The Gnat 750 first flew in 1989 and despite being "less high-tech" than Amber, boasted a significant number of design improvements. However, the loss of DARPA funding was too much for Leading Systems and Karem was looking at shutting down the company. However, San Diego-based defense contractor General Atomics was looking in 1990 to diversify its holdings outside of its core business of nuclear reactor technologies. One of its corporate directors was a former US Navy rear admiral, Thomas Cassidy, who joined General Atomics in 1987. He thought Karem's operation would be a good fit for what General Atomics was looking for and in 1990, General Atomics acquired Leading Systems and set up Abraham Karem and his team in a subsidiary General Atomics Aeronautical Systems to continue the development of the Gnat 750 UAV. 

In 1993, the Pentagon issued a requirement to rapidly field a surveillance UAV to support UN peacekeeping forces in the former Yugoslavia. The Gnat 750 was selected, but because the need was immediate and existing military acquisition procedures were too slow, the program was transferred to the CIA under the code name LOFTY VIEW. Since the CIA would be operating the Gnat 750 in secret, it fell outside of the purview of the Congressional mandate the created the UAV JPO that inadvertently killed off the Amber program. By 1994 the first Gnat 750s were deployed to a CIA operating base in Albania for operations throughout the Balkans. The UAVs provided overhead surveillance for UN convoys as well as spotting artillery emplacements and the operating locations of the various belligerents in the wars that wracked the region through the latter half of the 1990s. The bad weather of the Balkans and the limited range of the Gnat's datalink proved to be the main issues that affected operations. 

While the CIA was getting the Gnat 750 operational over the Balkans, General Atomics Aeronautical Systems had secured funding under an advanced concept technology program. At the time, UAV development had been stratified into "Tier" levels based on endurance and performance. I had reviewed these Tiers a year ago in a previous blog posting that covered the development of top-secret stealthy Quartz UAV
In the 1990s, there were three "tiers" of UAV development based on operational capability. "Tier I" was for a low-altitude system that became the Gnat-750 UAV. "Tier II" was for a more capable medium altitude system based on the Tier I craft and that became the current Predator UAV family. The specification for "Tier III" would have been filled by the Quartz project, but with its cancellation, Tier III was split into two- Tier II+ was for the Quartz's performance without stealth and this became the RQ-4 Global Hawk UAV. Tier III- ("Tier III Minus") was stealthy but without the performance and payload of Tier II+. This design became the RQ-3 DarkStar. DarkStar, a joint effort between Boeing and Lockheed, had little in common with Quartz and itself would be canceled in 1999 in favor of further development of the Global Hawk.
General Atomics RQ-1/MQ-1 Predator
The Pentagon was issuing contracts for UAVs at each Tier. General Atomics's funding was for development of a Tier II UAV. The new design took the Gnat 750 and stretched the fuselage and lengthened the wings. The inverted-V tail, stalky retractable undercarriage, and pusher prop were retained (though with a more powerful Rotax piston engine). Since one of the weaknesses of the Gnat 750 was the limited range of its datalink, the new UAV had an enlarged nose section that had the imaging payload on the underside of the nose similar to what the Gnat 750's layout, but incorporated a satellite communications dish in a bulged radome as the new datalink. Use of a satcom datalink now meant that the UAV operators and pilots didn't even have to be in the same region as the UAV's area of operations. It was now possible for the crews to fly the UAVs from stateside bases using the satcom datalinks to fly the Tier II UAV anywhere in the world it was needed. 

Named Predator, the new Tier II UAV made its first flight in June 1994. Less than a year later during the Roving Sands 95 exercise at Fort Bliss, Texas, the Predators were used for the first time in an operational demonstration. They were so successful at Roving Sands that year that the USAF established its first UAV squadron, the 11th Reconnaissance Squadron at Indian Springs Auxillary Airfield in Nevada (later renamed Creech AFB in 2005) shortly after the exercise in Texas and just one month after Roving Sands, the first Predators were deployed to the Balkans under Operation Nomad Vigil. From July to November that year the 11th RS operated its Predators out of Gjader in Albania in support of Operation Deliberate Force, the NATO air campaign against Bosnian Serb forces. While more capable than the Gnat 750s operated by the CIA, the need for overhead surveillance was so great in the Balkans that both the Predator and the Gnat 750s operated simultaneously in theater. 

By 2001, the USAF had taken delivery of 68 Predator UAVs. Due to the steep learning curve in operating such a radically different type of aircraft, 19 were lost, but only 4 were confirmed to have been shot down over the Balkans. But it was only the beginning of how the Predator began to change the way air campaigns were fought. And that is subject matter for a future posting on this blog!
Sources: Birds of Prey: Predators, Reapers and America's Newest UAVs in Combat by Bill Yenne. Specialty Press, 2010, p37-40.
 Popular Science, September 1994. "Drones: Invented and Forgotten" by Bill Sweetman, p34.
Designation-Systems.net by Andreas Parsch. "Leading Systems Amber" and "General Atomics Gnat".
Photos: Federation of American Scientists, United States Air Force.

23 February 2011

Aviation Trivia of the Day is now Tails Through Time

I suppose this was a long time in coming. When I started out this blog nearly two years ago (it will be two years in March), the daily posts were fairly short and took me no more than five to ten minutes to put together. But as time went on, I wasn't satisfied with just some short aviation factoid or bit of trivia and each post became a bit longer and pretty soon I was adding a picture or two...or three...maybe four...and pretty soon each post became a bit more involved and required more of my time than when I first started this blog. Time constraints and real world obligations prevent me from devoting a full daily post of the depth and quality that I can only dream of doing on a daily basis in the spirit of "Aviation Trivia of the Day". 

After taking a week to mull things over, I decided to reorient this blog more along the lines of what I had once done for Airlinebuzz as well as my own aviation art blog, The Chicken Works. Back then I used to put together more involved posts for both the forum that started out under the heading "Aviation Postcards" and with the advice of some good friends on Airlinebuzz, soon evolved into "Tails Through Time" for my aviation art blog. I had also thrown in some daily aviation trivia on that blog, but found that many folks were finding that my own artwork was getting buried under my aviation trivia. So I started this blog as a spin off but found that over the last two years I've more or less migrated to the format that resembled my more in-depth posts "Tails Through Time". The picture above is the original header I made for those posts and it inspired the newer version that's at the top of each page of this blog.

I'm still a consumptive reader of aviation books and have every intent of sharing what I come across here in this blog- just not on a daily format as I'd been struggling to maintain since the birth of my fourth child this past August. Rest assured to the regular readers that there will be regular postings here and I will guarantee you at least some of what shows up here will resonate with your inner avgeek child! The web address will stay the same, though.

Stay tuned !

16 February 2011

The Ground-Breaking Boeing Condor UAV

The Condor in flight
In the 1960s as the technology for unmanned aerial vehicles (UAVs) progressed, the USAF initiated two programs that would provide unmanned analogues to the premier airborne reconnaissance aircraft of the day, the Lockheed SR-71 Blackbird and the U-2. Both aircraft had their strengths and weaknesses and the USAF hoped to expand upon their capabilities with adjunct UAV reconnaissance aircraft. The companion program to the SR-71 Blackbird originated from the Lockheed Skunk Works as the D-21/Tagboard reconnaissance drone for the CIA. Possessing the same Mach 3 performance as the Blackbird, the D-21 was originally launched from the back of a modified A-12 Cygnus. However, after a disastrous fourth airborne launch that cost the launching aircraft and one of its crew, the D-21/Tagboard was moved over to the Boeing B-52 Stratofortress as the launching aircraft. After four failed operational missions in which the D-21 was lost, the program was canceled in 1971, at which time the second program which would have been a companion to the Lockheed U-2 was getting under way. Being a large jet-powered glider-like aircraft not too dissimilar in performance to the U-2, in 1971 the USAF initiated the Compass Cope program with Boeing and Teledyne Ryan producing prototypes- Boeing's design being the YQM-94 Gull (Compass Cope B) and Ryan's competing design being the YQM-98 Tern (Compass Cope R). After a competitive evaluation, Boeing's Gull was chosen in August 1976, to which Ryan lodged a protest. It was pointless at that juncture as the USAF canceled Compass Cope in 1977 before any production Gulls were built. 

But it wasn't the end of the story for Boeing's work for a high-altitude, long-endurance (HALE) UAV. The Defense Advanced Research Projects Agency (DARPA) was still interested in the idea of a HALE UAV for strategic reconnaissance. DARPA wanted to go one step further than the Compass Cope program, though. A contract was issued to Boeing for a HALE UAV that could operate for days at high altitudes carrying reconnaissance payloads that ranged for optical camera systems to electronic intelligence collection arrays to even an airborne synthetic aperture radar for all-weather/day-night surveillance. Boeing contracted with Burt Rutan who was using an all-composite structure in his record-breaking long-distance aircraft, Voyager. Boeing's design, aptly named Condor, used a predominantly composite structure with a wingspan of 200 feet, the same as that of the Boeing 747. The fuselage was only 68 feet long but was slab sided to facilitate the mounting of either an ELINT or SAR antenna array. Designed to be disassembled into sections and transported by a Lockheed C-5 Galaxy, the Condor's fully loaded weight was 60% fuel. 

Comparing the Condor and the 747
The wing's airfoil section was extremely efficient and provided natural laminar flow at altitudes in excess of 50,000 feet. Since the Condor was to be autonomously controlled, the wing had to have benign stall characteristics to simplify the control of the UAV. The wing was so efficient that it had twice the lift-drag ratio of the U-2- 40:1 compared to 20:1 for the spyplane. Since the wing would be highly flexible, a fuel transfer system was used to move fuel between wing tanks to reduce flexing in flight. The use of composites resulted in a wing that weighed only 2 lbs/square foot- an impressive feat considering that a commercial jetliner's wing comes in at approximately 30 lbs/square foot. 

The Condor was powered by two Teledyne Continental 175-horsepower six-cylinder piston engines that were superturbocharged for operation at very high altitudes. Each wing-mounted engine drove a three-bladed propeller 16 feet in diameter. Since the propellers were optimized for high-altitude cruise, at lower altitudes they would cause a significant amount of fuel burn and drag- as a result, a two-speed gearbox was used- one gear ratio for low-altitude flight and a different gearing for high altitude cruise. 

The flight control computer of the Condor was groundbreaking in that the Condor was the first UAV designed and flown autonomously without external control input from a remote pilot. Two Delco Magic 3 series computers were used as the brains of the Condor- the Magic 3 series computers were also used in the guidance systems for the Titan II ballistic missiles and the Delta family of rocket launchers. One computer acts as the primary computer with the second one operating in standby and ready to takeover should the primary computer fail. The control software consisted of only 60,000 lines of Fortran code- minuscule when one considers that today's RQ-4 Global Hawk reconnaissance UAV uses several million lines of software code! The Condor's computers were responsible for vehicle functions, flight control, and navigation using inputs from an inertial navigation system (this was in the days before GPS). The computer system was even designed to not only handle inflight emergencies but also prevent an enemy from taking electronic control of the UAV. Should that happen, the system was designed to recognize it was being taken over and immediately direct the Condor back to friendly territory. 

A microwave landing system was adopted to provide control of the Condor during takeoff as well as landing. Using a dolly, once the Condor reached 65 knots, it lifted off the ground and left its takeoff dolly behind. It would take anywhere from two to three hours for the Condor to reach its cruising altitude of over 50,000 feet. At cruise altitude, the Condor cruised at 200 kts, but its all composite construction made it a very small radar target and its piston engines had a very low infra-red signature- so despite its size and apparent leisurely cruise speed, it was a difficult target to track on most radars of the day. Descent for landing took two to three hours as well, and an extendable nosewheel and landing skids were used for landing. To save weight, instead of doors covering the skids and wheel, a replaceable Mylar sheet was used that the skids and nosewheel broke through on landing.

The Boeing Condor today at the Hiller Aviation Museum 
The Condor was developed in secret and its rollout in March 1986 was its unveiling to the world. It made its first flight on 9 October 1988 from Boeing's test facility at Moses Lake, Washington (the former Larson AFB). Since the rules on UAV operations in controlled airspace had yet to be fully written, a manned chase plane had to accompany the Condor during its transit through any controlled airspace. Only eight test flights were made with the last one on 28 November 1989, but the Condor set two world records- one for record altitude for a piston-engined aircraft at 67,028 feet on the fourth test flight and one for unmanned aircraft endurance at an impressive 58 hours, 11 minutes on the final test flight. Given that the test flights occurred over eastern Washington state, it's unlikely any operational reconnaissance payloads were carried, but to this day the exact nature of the payloads to have been carried- or even if they were carried- on the Condor remain classified. With a cost of $300 million, the Condor program did prove the viability of autonomous UAV flight as well as advanced composite construction and ultra-lightweight structures, but it lacking in military flexibility as well as its slow speed resulted in its cancellation after the final test flight. Only one Condor was built and flown, and in 1998 it was acquired by the Hiller Aviation Museum in the Bay Area where it can be seen on display today. It's the largest aircraft to be suspended in an interior museum display in the world. Not bad, even just sitting in the museum it still sets a record!

Sources: Birds of Prey: Predators, Reapers and America's Newest UAVs in Combat by Bill Yenne. Specialty Press, 2010, p20-32. 
Condor photo in the Hiller Museum by Joe May @ Travel for Aircraft- "Photo Funday- Boeing's Condor"

14 February 2011

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.

08 February 2011

How the USS Wasp Helped Defeat Rommel's Afrika Corps

Spitfire Mk.V makes its takeoff run on the USS Wasp
From 1940 to 1942 the Italian Regia Aeronautica and the Luftwaffe mounted over 3,000 sorties against the British fortress island of Malta in the Mediterranean in an effort to secure their supply lines to Field Marshall Erwin Rommel's Afrika Korps in North Africa. Despite repeated attacks, the Allies managed to keep Malta supplied, even with Axis airfields only sixty miles to the north in Sicily. With the coming of the harsh Russian winter in 1941, poor flying conditions put a temporary hold on most air operations over the Eastern Front and Hitler decided once and for all to deal with Malta. Aircraft idled on the Eastern Front were temporarily moved to airfields in Sicily and southern Italy to begin an intensive aerial bombardment as a prelude to an invasion of the outpost. By the end of January 1942, Malta's defenses had been reduced only a few dozen Hawker Hurricanes which were far outclassed by the Messerschmitt Bf 109s that routinely prowled the skies around the British garrisons. The Hurricanes were delivered to Malta by a Royal Navy aircraft carrier- launching from a point 600 miles west of Malta off the coast of Algeria for the long flight to Malta. Now the British planned to send Supermarine Spitfires the same way to bolster the defenses of the island. Supermarine's engineers devised a 90 gallon external belly tank to extend the range of the Spitfire as well as the addition of a dust filter under the nose to keep the carburetor air relatively grit-free.

On 7 March 1942 the HMS Eagle delivered fifteen Spitfire Mk.Vs to the island and by the end of the month, the Eagle made two more deliveries. But the Luftwaffe and the Regia Aeronautica stepped up the pace of their attacks on the beleaguered island fortress and the bombers and torpedo bombers that were based on the island to harass Axis shipping had to be withdrawn, providing a much needed respite for the Afrika Korps who could now be supplied unmolested. The small Spitfire force suffered heavy attrition both in combat and due to air attacks on the island airfields and by the end of the month, the only carrier available to deliver Spitfires to the island, the HMS Eagle, had developed steering problems that would lay her up for four weeks in the dockyard at Gibraltar. As a result, on 1 April 2942 Prime Minster Winston Churchill contacted President Franklin D. Roosevelt for assistance in getting more Spitfires to Malta. No Spitfires were available in Egypt to be spared, and the other two available Royal Navy carriers weren't suitable- the HMS Argus was too small and the HMS Victorious' lifts were too small for Spitfires. The Luftwaffe hoped to knock Malta out before the late spring thaw in on the Eastern Front. 
Spitfires being craned aboard the USS Wasp

On 10 April 1942 President Roosevelt ordered Operation Calendar- on that day the USS Wasp docked in Glasgow and loaded forty-seven Spitfires while retaining twelve Grumman F4F Wildcats for self-defense. Nine days later the Wasp and her escorting force of British warships entered the Mediterranean. On 20 April 1942 at sunrise off the coast of Algeria, the Wasp launched her Wildcat combat air patrol first followed by the twelve Spitfires on the deck and then the thirty-five Spitfires that were brought up from the hangar deck. Alll but one of the Spitfires made it to Malta, greatly bolstering the defenses. Unfortunately the following day the Luftwaffe struck back at the island's airfields and by the end of the day, only seventeen Spitfires were left operational. RAF repair crews labored under constant air attack to cannibalize battle damaged Spitfires that were beyond repair to get the others operational to fight off the next attack. Once again, Churchill contacted Roosevelt and on 29 April the USS Wasp arrived back in Glasgow for Operation Bowery. This time not only did the Wasp take aboard forty-seven Spitfires, but she was joined by the newly-repaired HMS Eagle which took seventeen Spitfires. At dawn on 9 May 1942 a force of sixty-four Spitfires departed; one crashed on takeoff, killing its pilot and a second Spitfire flown by Royal Canadian Air Force pilot Jerry Smith found once airborne that he couldn't draw fuel from the 90-gallon drop tank. Once the deck of the Wasp was clear, he managed to land safely back aboard the carrier despite never having landed on a carrier and his Spitfire not having an arresting hook! No barriers were engaged either, and as result, the US Navy pilots aboard the Wasp "unofficially" awarded him a set of gold Navy pilot's wings. 

Spitfires share the deck with Wildcats with the HMS Eagle following
Of the sixty-two Spitfires that set out for Malta that day, two were lost along the way. As each Spitfire landed, it was immediately refueled and rearmed while a Malta-based pilot replaced the ferry pilot, all while the engine remained running. RAF ground crews had each Spitfire airborne and ready to meet the next Luftwaffe attack in only 15 minutes! Over the next two days, the Spitfires and remaining Hurricanes on Malta exacted a harsh price from the Luftwaffe attackers, but by this point, the weather was improving over the Eastern Front and Hitler ordered the aircraft transferred to the Mediterranean for the Malta operation moved back to Russia. The Regia Aeronautica was given responsibility for knocking out Malta's defenses but never came close to achieving the near-defeat of the fighter defenses of April and May of that year. Between 18 May and 8 June another seventy-six Spitfires were delivered to Malta, this time by Royal Navy carriers, but it never matched the effect of the USS Wasp making just two deliveries, leading Churchill to quip "Who says a wasp can't sting twice?"

The overall effect of having Malta as a base of operations against Axis shipping in the Mediterranean cannot be understated- of the Axis merchant ships that provided the lifeline to Erwin Rommel's Afrika Korps, 70% of Italian merchant shipping was sunk by Malta-based aircraft and 23% of German merchant shipping was sent to the bottom of the Mediterranean by the RAF on Malta. Had the British lost Malta, the outcome of the war in North Africa might have been very different.

Source: Military Aircraft Monthly International, Volume 10, Issue 1. "Air Wars: Spitfires to Malta" by Dr. Alfred Price, p4-11.

05 February 2011

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.

04 February 2011

Dr. Hans Multhopp's Raven and Its Legacy

Dr. Hans Multhopp and a model of his Ta 183 fighter
By 1942 both Messerschmitt and Heinkel had flown jet fighter prototypes but other great fighter aircraft manufacturer of Germany at the time, Focke-Wulf, was lagging behind in jet aircraft development with the technical director of the company, Kurt Tank, still working on preliminary ideas for a jet fighter aircraft. Tank's first designs resembled the Heinkel He 162 with a single, dorsal-mounted engine. As Tank refined the design further, the engine moved into the fuselage with a nose intake, then it got lateral intakes, twin fins and finally ended up as a single-engine twin-boom fighter that resembled the De Havilland Vampire and was named the "Flitzer" (Dasher). However, Tank's protege in the company, Hans Multhopp, had been working on something even more spectacular than the Flitzer. Multhopp joined Focke-Wulf in 1938, having been recruited by Tank himself from the University of Gottingen where he worked under the famed aerodynamicist Ludwig Prandtl. By 1940 Multhopp was second-in-charge of the company's aerodynamics department and by 1943 Tank had promoted him to head the company's advanced design bureau. It was here that Multhopp developed what was called Project V. Multhopp had christened his design "Huckebein" after a mischievous raven in a children's cartoon of the day. The Huckebein had sharply swept wings and a raked back T-tail that gave it an appearance that was nothing like any design in the works anywhere at the time. 

Kurt Tank's Flitzer design
Tank was dubious about the features of the Huckebein and had scale models of both the Flitzer and the Huckebein built and tested. Despite the tests not uncovering any flaws with the Huckebein, Tank continued work on his own Flitzer but by 1944 it was quite apparent that it couldn't deliver the performance the Luftwaffe desired, which was for a jet fighter aircraft that could outperform the Messerschmitt Me 262. Even though the Me 262 was quite capable in many respects, the German air ministry, the RLM, had overstated the progress of the Allies in jet fighter aircraft development. In addition, by 1944 it was apparent that the Boeing B-29 Superfortress could outperform the B-17 and B-24 bombers that were hitting the Reich regularly. The main drawback of the Me 262 was that in using two engines, it used up per aircraft twice the scarce materials than a single-engined aircraft. Because of this, the RLM and the Luftwaffe exercised even tighter control over fighter aircraft development that in hindsight, were excessively bureaucratic. 

In 1944 with Tank having to accept that the company would have to focus its development resources on the Huckebein, the RLM issued a specification for a high performance fighter powered by a single Heinkel HeS 011 jet engine. Messerschmitt submitted what was to become the P.1011 fighter. Focke Wulf submitted Multhopp's Huckebein and even seaplane builder Blohm und Voss submitted a fighter design. Through the winter of 1944-1945 RLM officials and Luftwaffe staff endlessly deliberated the merits of each design and even discussed revamping the specification- as Allied armies were approaching the Rhine in the West and the Soviet Red Army was continuing its relentless push on the Eastern Front. Junkers was then invited to submit their design as well. With no progress being made, the Luftwaffe High Command called an emergency meeting in February 1945 to resolve the matter and the Focke Wulf Huckebein was selected as the Ta 183 ("Ta" in reference to Kurt Tank) to be the interim design while the Messerschmitt design was regarded as the optimal design for further development to supplant the Ta 183 in service. Plans were drawn up sixteen test Ta 183 aircraft with a maiden flight planned for May or June 1945 with the first production fighters being delivered to the Luftwaffe in October 1945. 
Ta 183 Design III, this influenced the Saab J29 Tunnan

The Ta 183 was aerodynamically very advanced with a 40 degree, thin, swept wing that had low wing loading for high altitude performance and maneuverability. The sharply raked back vertical fin mounted a T-tail unit that was used only for trimming purposes with pitch and roll to be handled only by the wing surfaces. The cockpit was pressurized and aircraft was armed with hard-hitting 30mm cannon. An alternate variation of the Ta 183 was also envisioned with a less sharply swept wing, a conventional tail unit and longer fuselage- this was the Design III which Tank worked on while Multhopp refined the original Ta 183 which was designated Design II. 

The Ta 183 is a popular subject of "What-If" modeling
Work proceeded quickly after that February meeting, but the following month the Allies crossed the Rhine into Germany and work on the Ta 183 under Hans Multhopp and Kurt Tank ground to a halt when the British Army captured Bad Eilsen, the location of Focke-Wulf's design department. The fall of Nazi Germany left the Allies an impressive treasure trove of aeronautical progress. The British initially failed to realize the technological leap the Ta 183 represented when they sifted through the captured material at Bad Eilsen. The Soviets, however, were quick to realize the Ta 183's potential, having found a complete set of plans on microfilm when they captured the RLM headquarters in Berlin. While the plans were examined by Artyom Mikoyan and Mikhail Gurevich of the MiG design bureau, it would be fallacy to say that the MiG-15 is a copy of the Ta 183 as Mikoyan and Gurevich were talented designers in the their own right. Perhaps their examination of the Ta 183 plans confirmed their own intuitions on how best to proceed with the MiG-15. There is no doubt, though, that Sweden managed to get a hold of the Ta 183 plans and data and that it is believed to have influenced their own design work on the Saab J 29 Tunnan fighter. 

Following the end of the Second World War, Kurt Tank and Hans Multhopp parted ways, with Tank moving on to work on projects in Argentina and India (subject for future blog posts, stay tuned!). Multhopp and a team of his assistants went to work at Farnborough in the UK and developed plans for a transonic research aircraft powered by an Rolls-Royce Avon turbojet with 60-degree swept wings and a T-tail with the pilot sitting prone in the shock cone of the nose intake. However, Britain was economically spent after the war and Multhopp's design never got built. In 1949 he moved to the United States and went to work with the Glenn L. Martin Company where he worked on two designs that also had T-tails- the XB-51 tactical bomber and the P6M Seamaster jet flying boat. He would later become the chief scientist for Martin Aircraft and his career would culminate with Martin's pioneering work on lifting body spaceplane designs like the X-23/PRIME and the X-24 which provided much data for the NASA Space Shuttle program. 

While the Ta 183 was only one of many advanced designs being worked on in Germany during the Second World War, it is probably the most emblematic of Germany's influence on postwar aircraft design. Many designs that were considered ground breaking in the 1940s like the Boeing B-47 Stratojet and the North American F-86 Sabre, originally began as less-than-spectacular straight wing designs that were reworked to incorporate what was being learned from the analysis of captured German aeronautical research.

Source: Aircraft, January 2011, Volume 44, Number 1. "The Luftwaffe's Last Hope" by Bruce Hales-Dutton, p46-50.

01 February 2011

The Messerschmitt Me 163 Komet Takes to the Air Again

The all-red scheme is striking on the Me 163 replica glider
Towards the end of the Second World War, Luftwaffe pilot Jozef Kurz went through pilot training for the Messerschmitt Me 163 Komet rocket interceptor but the war ended before he was able to make a powered flight in the aircraft. Years after the end of the war, Kurz had become an avid glider pilot and decided to build an airworthy replica of the Komet. Using hundreds of original microfilm drawings to create the needed building plans, Kurz had to make certain compromises in the design but remained as faithful as possible as he wanted his replica Komet to be as externally accurate as possible. The biggest difference was the use of wood in the replica instead of metal as was used on the original design. This resulted in some changes in the internal structure which also had the vertical fin as integrated structure instead of a separate structure on the original aircraft. But Kurz was able to keep the external appearance nearly faithful to the original, even using the Gottingen 765 wing profile. Like the original, Kurz's replica glider had two wing spars and the wings were removable reduce its hangar footprint and facilitate road transport. Because the replica was made of wood, it had a weight of 868 pounds compared to the empty weight of the original Me 163 Komet of nearly 4,200 lbs. 

The control surface arrangement of the replica glider was also faithful to the original, with fabric-covered coupled elevator/ailerons on the outboard wings and large trim tabs on the inner wings. Fixed slats were also built into the outer wings similarly to the original. Aside from using wood in the construction (and the obvious lack of the Walter HWK 109 rocket motor), the other main change from the original was using a single central wheel integrated into the central landing skid instead of using the jettisonable twin-wheel dolly.

Kurz painted his replica Komet in the markings of the most famous Me 163- the Me 163B flown by Erprobungskommando 16 (EK16- an operational test unit) commander Wolfgang Späte on the Komet's first operational combat mission in 1944. Though no pictures exist of the red Komet, Späte had written two books about his experiences in the Komet and described the plane he flew on the first operational mission- he had no knowledge beforehand that his ground crew painted the Komet in homage to the Red Baron- his accounts indicate the paint added about 40 pounds to the Komet and while it was audacious move and reflected confidence in the rocket interceptor's performance, Späte ordered the aircraft repainted in standard camouflage on his return. Kurz first flew his own Komet replica on 18 June 1996 with the registration D-ESJK. Designating his glider the Me 163BS, Kurz made numerous short test flights before unveiling it at a vintage aircraft fly-in in September 1997. Its last flight in Kurz's hands was at the Berlin ILA 2000 air show. With only five flight hours logged, Kurz sold the replica to EADS (which then had just been formed as the parent to Airbus Industrie and Eurocopter) for display in the Flugmuseum Messerschmitt at Manching, Bavaria. 

Note the EADS logo under the cockpit
German aircraft historian Werner Blasel, who had been the main driving force behind the establishment of a heritage flight at Manching as part of the museum, felt that it would have been a waste for the replica glider to remain as a museum display given that it had already proven its airworthiness. Work to return the glider to flying status began in 2004 and was completed in 2006. The most apparent changes were the addition of triangular side windows behind the cockpit, a new canopy, and external aerials that more closely resembled the original Komet. Since there were no longer plans to fit any sort of engine in the fuselage, structural rework was carried out to better integrate the wings with the fuselage structure to allow the aircraft to take the stresses of higher forces. Modifications were made to the undercarriage to facilitate ground handling and the slats were reprofiled to improve the glider's handling characteristics. Lead ballast was also added to better balance the aircraft in flight. The aircraft was re-registered as a one-off glider with the civilian registration of D-1636. Historical markings were added (sans Swastika, which is prohibited from display in Germany) and it made its second maiden flight on 20 June 2006 after which it joined the EADS Heritage Flight fleet at the Flugmuseum Messerschmitt. 

At the end of 2010 the replica Komet had flown forty hours. Two pilots with the EADS Heritage Flight are rated in the glider, using a Dornier Do 27 tow plane to get to altitude. Taking 10 minutes to reach 4,000 feet, the Komet is said to be most demanding on the tow line and is much easier to handle in free flight. As the aircraft was optimized for high speed flight, its gliding performance wasn't on par of purpose-built sport gliders but has nonetheless been a hit at air shows in Europe. 

Source: Aircraft, January 2011, Volume 44, Number 1. "Red Alert" by Marc Frattini and Dr. Andreas Zeitler, p38-45.