Sunday, January 18, 2009

Weekend Wings #31: The Last of the Big Bangers

In 1943, the tide had turned in World War II. Germany’s long string of victories in the West and in the East had been decisively halted at Stalingrad in Russia, El Alamein in Egypt, and in North Africa with the Torch landings.

In the Pacific, Japan’s advance had been halted on land in the Guadalcanal campaign. 1943 saw the launch of Operation Cartwheel, a two-pronged assault commanded by General Douglas Macarthur in the New Guinea campaign, and by Admiral Chester Nimitz in the Solomon Islands campaign. Both prongs would eventually meet in the Philippines in late 1944. At sea, the Imperial Japanese Navy had been decisively defeated at the Battle of Midway in June 1942, losing four of its aircraft-carriers and the core of its trained naval aviation corps. It remained a formidable threat, but the US Navy now had its measure, and the growing flood of new-construction aircraft carriers and other warships emerging from US shipyards promised a growing naval supremacy in the Pacific, permitting the island-hopping invasions planned for 1944 and 1945.

Already, US strategists were turning their eyes upon Japan itself, and beginning to plan for its invasion and subjugation. However, there were a number of problems to be resolved before any invasion could succeed; and many of these revolved around air operations against Japan.

The ‘heavy’ bombers of the day, the Boeing B-17 Flying Fortress:

and the Consolidated B-24 Liberator:

had a radius of action (with full bomb load) of less than 1,000 miles (which could be extended if a lighter bomb-load was carried). If they were to be used to bomb Japan, island bases within that radius would be required - but such bases would also be within range of Japanese air raids.

The planned ‘super-heavy’ bomber, the Boeing B-29 Superfortress:

was experiencing inmense difficulties in development. It would prove to be a more expensive weapons system than even the Manhattan Project, consuming billions of dollars to set up brand-new factories, and requiring new technologies never before integrated into a bomber aircraft. If it could be made to work, it would have a much longer range than the B-17 or B-24. This would allow more distant island bases to be used, out of range of Japanese aerial retaliation. However, in 1943, there was no guarantee that this would be the case. Alternatives had to be examined, in case the B-29 program failed to live up to expectations and other solutions had to be found.

(As a matter of historical interest, although the B-29 was made to work under the pressures of war - and at the cost of significantly greater casualties due to mechanical failure, in both aircraft and personnel, than would ever have been accepted in peacetime - it was never fully satisfactory in operational service. Only when further developed, after World War II, first into the B-29D and then into the B-50 Superfortress, did it achieve a satisfactory service record. This will be the subject of a future Weekend Wings article.)

Naval attack aircraft were divided into two classes. Torpedo bombers were intended for use against ships. The Douglas TBD Devastator:

with which the US Navy had started the war, and which had seen such catastrophic losses at the Battle of Midway, was being replaced by the Grumman TBF Avenger.

Dive bombers were used against both naval and land targets. The Douglas SBD Dauntless (shown below over USS Enterprise off Guadalcanal in December 1942):

which had sunk the Japanese carriers at Midway, was being replaced by the Curtiss SB2C Helldiver:

Unfortunately, the Helldiver was not without severe teething problems, causing its crews to award it several derogatory nicknames.

However, even the new torpedo- and dive-bombers were considerably slower than Japanese fighters, and needed fighter escort to take on heavily-defended targets. They also required multiple crew members, which put an additional strain on the already overstretched manpower and training resources of the Navy. Furthermore, their radius of action was relatively short - less than 500 miles for the Helldiver and less than 400 for the Avenger - and their bomb load relatively light (up to 2,000 pounds internally, plus up to a further 500 pounds on each of two hardpoints beneath the Helldiver’s wings).

If the US Navy were to join in the aerial attack on Japan, its aircraft carriers would be dangerously exposed to Japanese counter-attack with such short-ranged aircraft. Ideally, the carriers needed to ‘stand off’ the coast of Japan at a range too great to allow the enemy to locate or attack them. This would require longer-ranged attack aircraft - and they’d have to carry a greater weight of ordnance, too, if they were to compete with USAAF bombers. The latter could deliver three to four tons of bombs per B-17 or B-24, and up to ten tons in the B-29, whereas current US Navy attack planes could manage no more than one to one-and-a-half tons. Clearly, improvements were needed in both range and payload.

Furthermore, such operations would mean that more fighter aircraft would have to be carried aboard the carriers, both to defend their mobile ‘airfields at sea’ and to escort attacking aircraft to and from their targets. That would mean a reduction in the number of attack aircraft aboard the carriers: so the smaller number of attack planes would have to make up for this by carrying more ordnance per aircraft. This was complicated by the division of US Navy attack aircraft into either torpedo- or dive-bombing squadrons. Already the exigencies of war meant that torpedo-bombers were being used on conventional bombing missions, while dive-bombers were being used for level bombing and close air support. It would be of great benefit to the Navy if a single strike aircraft could replace both types, capable of carrying bombs or torpedoes at need, and fulfilling both missions. Furthermore, if the number of crew required for each aircraft could be reduced, this would save on already-scarce manpower, and would also simplify training requirements.

The carrier fighters, too, would need greater range. The USAAF had long-range fighters under development, particularly the superb P-51 Mustang:

This fighter was to transform the bomber offensive over Europe in 1944, and would undoubtedly be introduced in the Pacific theater as soon as suitable bases were available. (It was eventually based in the Philippines and on Iwo Jima and Okinawa, flying escort missions for B-29's based in the Marianas Islands.) However, the US Navy’s fighters, principally the Grumman F6F Hellcat:

and (initially operated by the US Marine Corps from shore bases, and later also from carriers) the Chance Vought F4U Corsair:

were not as long-ranged as the Mustang, so that their ‘parent’ aircraft-carriers would have to operate closer to the enemy if they were to provide escort to strike aircraft.

In reality, of course, as events unfolded, many of these concerns proved to be unfounded. The Japanese air defenses were so eviscerated by US fighters that they proved unable to defend their country effectively against air strikes by both the USAAF (with B-29's) and the US Navy (with Avengers and Helldivers). They were also unable to operate effectively against US Navy aircraft-carriers in the conventional sense, although their kamikaze attacks off the Philippines and Okinawa caused grievous damage and loss of life. However, in 1943, none of this could be anticipated: so planners had to think of alternatives, and ways to meet the demands they foresaw.

The US Navy put its best minds to addressing these problems. They adopted a two-pronged approach. One would be to develop an ‘all-in-one’ aircraft, that could fight, bomb, and do anything and everything demanded of any current carrier-based aircraft. The other would be to develop a better strike aircraft, with longer range, carrying more ordnance, and requiring less crew than existing aircraft, and capable of fulfilling the torpedo-, dive- and conventional bombing functions, as well as providing close air support.

These efforts would produce the ‘last of the big bangers’, the biggest, most powerful and most complex single-engined, piston-engined aircraft ever designed for use aboard aircraft carriers, and the last of their kind in the world. We’ll examine each approach in turn.

The Boeing XF8B-1: The great all-rounder.

On May 4th, 1943, Boeing was given a contract to develop and build three prototypes of a single-seat fighter-bomber aircraft that could ‘do it all’. It would serve as an interceptor for fleet defense; a long-range escort fighter; and a dive-bomber, torpedo-bomber and level bomber as well. It was to carry up to 7,200 pounds (well over three tons) of bombs or aerial torpedoes, and be armed with six .50-caliber machine-guns in the wings. The latter specification was later upgraded to six 20mm. cannon. It was to have a radius of action, with warload, of at least 1,000 miles, and performance sufficient to defeat any likely Japanese opponent.

Boeing’s response was a technological marvel of its time. The XF8B-1 (which was never given a name) was a very big plane for its day, having a wingspan of 54 feet, length of almost 44 feet and a loaded weight of over 20,000 pounds. To give it sufficient power, Boeing selected the brand-new Pratt & Whitney R-4360 Wasp Major engine, which would later be used to power the B-50 Superfortress, Convair B-36 (colloquially known as the ‘Peacemaker’), and other leviathans of the air. The early version of this 28-cylinder, four-row radial engine developed a genuine 3,000 horsepower, rising to 4,300 horsepower in later models, far greater than any competitor at the time.

The sheer power of this engine posed headaches of its own. All single-engined aircraft using a single propeller experience the effect of engine torque when power is applied. This normally manifests itself as a swinging of the aircraft in the direction of rotation of the propeller. On lower-powered aircraft, this can be easily controlled by the pilot, sometimes with the aid of trim tabs that apply a set amount of rudder correction. However, the enormous power of the Wasp Major made its torque almost unmanageable at low speed (something that was to doom another aircraft developed in response to the US Navy’s 1943 requirements - more about that later). To overcome this problem, and to harness all of the available power, Boeing introduced the first contra-rotating propeller designed for a US combat aircraft from its inception. In effect, this was two three-bladed propellers, mounted one behind the other. One turned to the left, the other to the right. They thus canceled out each others’ torque, and made the aircraft very stable and easy to handle, despite its huge engine’s power.

To meet the warload and range requirements, Boeing adopted an innovative solution. An internal bomb bay could handle up to 6 500-pound bombs, or two 1,600-pound bombs, for a total load of up to 3,200 pounds. Large internal fuel tanks were also provided. Two external hardpoints were placed beneath the wings. They could carry either external fuel tanks, or one 1,600-pound bomb each, or one 2,000-pound torpedo each. This gave either a very long range of almost 2,500 miles with a 3,200-pound internal bomb load, or a range of about 1,500 miles (on internal fuel alone) with an internal and external warload of up to 7,200 pounds.

Development of the XF8 was slowed by Boeing’s commitment to the B-29 program, including the massive effort required to overcome that bomber’s teething troubles. However, the B-29 program also assisted the XF8: the latter’s tail design shows clear signs of the B-29's influence. In addition, the experience Boeing gained with the P&W Wasp Major engine in the XF8 program would help lead to that engine’s selection to replace the Wright R-3350 engines of the B-29 in the post-war B-29D/B-50 program.

The first prototype of the XF8 flew in November 1944.

In order to speed up development, a second seat was installed in the spacious cockpit, allowing a flight engineer to accompany the test pilot and record engine settings. The huge size of the aircraft made this easy. Two more prototypes followed, but their production was delayed by Boeing’s commitment to the B-29 program, and they only arrived after the end of the war. The final prototype is shown below in the only color photograph of the XF8 known to survive.

The XF8 was an immediate success, delivering everything the Navy had asked for. Its performance was so superb that one of the prototypes was even tested by the USAAF, to see whether it might be suitable for land-based air forces as well. However, by the end of 1944, when it first flew, the predictions of mid-1943 had been shown to be unfounded. The US Navy’s current aircraft proved able to handle combat operations against Japan, and to defend the fleet against Japanese counter-attacks. The long-range stand-off attacks envisioned in 1943 never became necessary. Furthermore, the advent of jet engines promised a whole new era of aircraft performance, and piston-engined aircraft rapidly lost their priority for development. Finally, the US armed forces needed Boeing to concentrate on the development of advanced bombers, tankers and transport aircraft, building on the success of the B-29 program.

As a result of all these factors, the US Navy decided not to place the XF8 into large-scale production. Despite the advent of the jet age, Boeing was offered a small production contract, as the aircraft was simply so good that the aviation powers that be didn’t want to do without it altogether. Unfortunately, Boeing’s assembly lines in 1946/47 were filled with B-50 bombers and C-97 Stratofreighter transports. The company was also preparing to produce the Boeing 377 Stratocruiser (a civilian airliner based on the C-97), the KC-97 Stratotanker (another C-97 derivative) and the B-47 Stratojet strategic bomber. It could not afford to divert its production resources to a short run of fighter-bombers, from which little profit could be expected. Reluctantly, therefore, the XF-8 contract was declined.

However, the fact that the XF8 never entered production is not to imply that it was in any sense a failure. Quite the contrary - it was a spectacular achievement.

As a bomber, the single-engined XF8 could carry a heavier bomb load, at a higher speed, over a comparable (sometimes longer) range, than any twin-engined medium bomber of World War II, including the British Vickers Wellington and de Havilland Mosquito; the German Junkers Ju-88; and the US Douglas A-20 Havoc, Douglas A-26 Invader, Martin B-26 Marauder, and North American B-25 Mitchell.

As a fighter, the XF8 had a comparable practical (as opposed to theoretical) service ceiling, was more heavily armed (in its 20mm. cannon-equipped version), and was as fast or faster than, any piston-engined fighter of any World War II power, Allied or Axis. Furthermore, its contra-rotating propellers removed engine torque from the sighting equation, making it a more stable gun platform than most other fighters, and allowing for much more accurate shooting. Its only deficiencies as a fighter were its slightly slower rate of climb and its slightly lesser maneuverability, both due to its size and weight: but the right tactics could have ensured that these minor shortcomings would not have presented problems operationally, just as pilots of the F6F Hellcat and F4U Corsair (both less maneuverable than their Japanese opponents) were able to develop tactics to overcome this problem.

(Speaking of rate of climb, the champion ‘climber’ of World War II was the Grumman F8F Bearcat:

This was designed as an interceptor to stop Japanese kamikaze attacks on US aircraft carriers. It arrived too late to see combat service, but its climbing performance blew away all other aircraft of the era. In 1946 an F8F-1 set a time-to-climb record of 10,000 feet in 94 seconds, starting from standstill on the runway. This record stood for a full 10 years before jet aircraft developed sufficiently to break it.)

When fitted with external fuel tanks instead of bombs, the XF8 could carry up to 3,200 pounds of ordnance internally, and function as a fighter-bomber on a ‘search-and-destroy’ mission over a longer range than any other fighter aircraft of World War II. Its range was 70% greater than its nearest rival in this respect, the North American P-51 Mustang, even when the latter also carried external fuel tanks.

If the Boeing XF8 had been requested in 1942 and first flown in 1943 (instead of in 1943 and 1944, respectively, as was the case in reality), there’s little doubt that it would have been ordered in the thousands, and would probably have played an important part in the final year of the war against Japan (not to mention the Korean War in due course). It might have proved as versatile in its day as the McDonnell Douglas F-4 Phantom II did in the 1960's and 1970's. Sadly, this was not to be.

Regrettably, none of the three prototypes have survived. The last was scrapped in 1950. That’s a great pity, as the Boeing XF8 represented the pinnacle of piston-engined multi-role naval aircraft development. There has never been another aircraft quite like it.

Martin and Douglas: The ‘do-it-all’ strike aircraft

While leaving Boeing to develop a ‘do-everything’ solution to their naval aircraft needs, the US Navy planners also launched a competition to design a new strike aircraft. It was more narrowly focused than the requirement issued to Boeing, concentrating on the torpedo- and bomb-carrying functions only. The winner would be required to replace both the TBM Avenger and SB2C Helldiver in the torpedo-bombing, dive-bombing and level bombing roles, and also provide close air support.

Four companies were selected to develop prototypes. The overall program received the designation XBT, for Experimental Bomber Torpedo. A fourth letter would designate the manufacturer in each case, followed by ‘-1’ to indicate the model number. We’ll examine the two unsuccessful competitors briefly, then go on to consider those that reached production.

The Curtiss XBTC-1 was a single-engined, low-wing monoplane with retractable tail wheel. Like the Boeing XF8, it used the Pratt & Whitney Wasp Major engine. However, in late 1944 the Navy decided to proceed with the Douglas and Martin entries, so the XBTC-1 was not developed further. No photographs of this version appear to have survived.

Undaunted, Curtiss developed a lower-powered, two-seat version, the XBT2C-1, using a Wright R-3350 engine, which first flew in 1946.

This had reduced armament and was fitted with radar. It was intended for use as a carrier-based night fighter and intruder aircraft. The US Navy ordered ten pre-production aircraft, of which nine were built, but the program was not developed to full production status.

The other unsuccessful entrant was from a little-known aircraft company. Fleetwings was founded in the 1920's, and began manufacturing stainless steel aircraft structures and components in the 1930's, taking over the factory of the defunct Keystone Aircraft Corporation in 1934. In March 1943, Henry J. Kaiser bought the company, which was renamed Kaiser-Fleetwings. Almost immediately the new company was selected by the US Navy as one of four competitors to develop its new strike aircraft.

Kaiser-Fleetwings designed the XBTK-1 in response to the Navy’s requirement.

It was powered by a Pratt & Whitney R-2800 radial engine, the same as used in the F6F and F4U fighters, developing some 2,000 horsepower.

Five prototypes were built, and the aircraft’s innovative dive brakes (shown deployed in the top and bottom pictures of the sequence below) attracted some interest: but its lower power, smaller ordnance capacity and lower range than its competitors meant that it was not approved for development to production status.

The Martin XBTM-1 (known within the company as the Model 210) was an aircraft with awesome potential, but was crippled by design flaws. It was powered by the same 3,000 horsepower Pratt & Whitney Wasp Major engine as the Boeing XF8, but Martin decided to stick with a traditional single four-bladed propeller. This immediately produced immense handling problems at low speed, where the torque of the massive engine could make the aircraft almost uncontrollable. (Boeing, you will recall, overcame this completely by installing a contra-rotating propeller on the XF-8. One can only wonder why Martin didn’t learn from Boeing and move to this solution in subsequent prototypes. It would almost certainly have transformed the XBTM-1 from a lemon into a superstar.)

The XBTM-1 had four 20mm. cannon in its wings, and fifteen hardpoints for external ordnance beneath wings and fuselage, capable of carrying up to 10,698 pounds - the heaviest underwing load of any single-engined piston-engined aircraft in history. The prototype first flew on August 26th, 1944, and immediately exhibited the handling problems that were to plague it for its entire service life. Engine torque was so strong that the aircraft was almost uncontrollable on take-off and during landing - if full power were applied at too low a speed, when the control surfaces did not have adequate airflow to exert their normal pressure, the aircraft could go out of control in a heartbeat.

These problems caused long delays in getting the XTBM-1 to production status. It would be December 1946 before the first flight of the production AM Mauler (as the aircraft was known in US Navy service). In the interim, the Pratt & Whitney Wasp Major engine had been replaced by the smaller and lighter Wright 3350 Cyclone, which was deliberately angled off-center by two degrees to the right, to assist in controlling its torque. Hydraulic flight controls had also been developed, as unassisted controls had proved incapable of handling the demands of so heavy an aircraft.

The initial production aircraft proved to be unsuitable for carrier operation, with many suffering damage to their rear fuselages from their tail hooks, so that modifications had to be carried out before they could be assigned to carrier-based squadrons in early 1948. Unfortunately, the delays caused by the Mauler’s many teething troubles meant that Douglas had been able to get its aircraft (of which more later) into carrier service a full year earlier. Furthermore, fleet pilots found the Mauler very difficult to control, and it proved to be a maintenance nightmare. Its inadequate low-speed handling proved very difficult aboard an aircraft carrier, with more than one Mauler simply ‘waltzing’ over the side when the throttle was rammed full open at too low a speed. In an emergency, pilots wanted to be able to use all the power at their disposal - but in the Mauler, this could kill them. In consequence, some pilots cynically joked that the AM designation actually stood for ‘Awful Monster’.

Despite its problems, the Mauler could carry an enormous bombload. One (shown below) flew carrying three 2,200-pound torpedoes, twelve 500-pound bombs, and a full load of 20mm. ammunition, for a total ordnance lift of 12,648 pounds, a record for a single-engined aircraft at the time.

The aircraft in the background is carrying a 1,600-pound bomb beneath the fuselage, two 11.75" 1,250-pound ‘Tiny Tim’ air-to-ground rockets, and twelve 5" 140-pound HVAR ‘Holy Moses’ air-to-ground rockets. Some pilots were very impressed by such ordnance-carrying capability, despite the Mauler’s handling problems, and in order to counteract the ‘Awful Monster’ label applied to the aircraft by many, insisted that its ‘AM’ designation actually stood for ‘Able Mabel’. However, few were convinced.

Although the Douglas competitor to the Mauler (of which more in a moment) was smaller and carried fewer bombs, it was much more reliable in service, far easier to handle, and very much more popular with its pilots. In 1950, the US Navy decided to standardize on the Douglas aircraft for carrier use, and the Mauler was assigned only to land-based units. Within a few months, even they switched over to the Douglas aircraft. The Mauler soldiered on with Reserve units for a few years, but was finally retired in 1953, just five years after entering carrier service. Only 151 were built.

I’ve sometimes wondered what the Mauler’s fate might have been if Martin had adopted Boeing’s solution of a contra-rotating propeller to handle the enormous power of the Pratt & Whitney Wasp Major engine. That would have solved most of its handling problems, and with its huge bomb-load, the aircraft might have proved itself very successful in the Korean War, ensuring its future. Sadly, we’ll never know.

The last of the four companies competing for the US Navy contract was Douglas Aircraft Corporation. It was already working on the design of the XSB2D-1 Destroyer for the US Navy. This tricycle-landing-gear, gull-winged aircraft first flew in April 1943, and Douglas was awarded a contract to produce 358 of them.

Originally intended as a replacement for the SBD Dauntless dive-bomber, Douglas re-worked the SB2D into a single-seat version. However, Ed Heinemann, chief engineer of Douglas’ El Segundo division, was uncertain whether the SB2D would be successful. In particular, it did not meet the requirements of the XBT competition in terms of bomb load and range.

Douglas was also designing the TB2D Skypirate heavy torpedo bomber (also known as the Devastator II), intended for operation from the proposed Midway-class aircraft carriers.

This enormous aircraft also used the Pratt & Whitney Wasp Major engine, and adopted a contra-rotating propeller, as Boeing had done with the XF8. It weighed almost 35,000 pounds at full load, and was so large and heavy that it would not have been suitable for general carrier operation. A prototype flew in 1945, but the aircraft never went into production.

Heinemann and a team of designers flew to Washington in June 1944 to discuss progress on the SB2D and TB2D with Navy officials. He proposed that the Navy cancel the contract for the SB2D and allocate the funds to an entirely new BT2D development, more in line with the XBT competition requirements, which he offered to present to them in thirty days’ time. To his astonishment, the Navy representatives directed him to present the new design to them the following morning! Since it was not even in blueprint form yet, this would take some doing. However, as one author has noted:

In truth, Heinemann wasn’t wholly unprepared. He and his top staff members, Leo Devlin and Gene Root, had for several weeks been sketching out ideas for a totally new design. Their latest conception had virtually nothing in common with the earlier BTD. Though using the same Wright R-3350 power plant, it was a far simpler design, featuring a conventional tailwheel layout and straight-tapered, low-mounted wings beneath which all ordnance would be carried on external racks. For dive-bombing, rather than the common split-flap arrangement, the design called for three board-type speed brakes, which extended from the fuselage sides and belly. Gun armament consisted of two wing-mounted 20mm cannons.

After only a few hours’ sleep, Heinemann, Devlin and Root left the hotel early, giving themselves extra time to have blueprints made from the drawings. The presentation was over by late morning, and the three men were told to keep their seats and wait. By noon they got an answer: Douglas was authorized to cancel the BTD program and fund construction of 25 preproduction examples of the proposed model, the XBT2D-1. BuAer gave them exactly nine months to get the plane in the air. When Heinemann returned to the El Segundo plant, his instructions to his staff and employees were terse: “Nothing must interfere with the completion of this aircraft on schedule.”

Despite the successful conclusion of the BuAer meeting, Heinemann was conscious of the fact that he had committed his company to a risky game of catch-up. The Curtiss and Kaiser-Fleetwings prototypes were falling behind schedule, but Martin, with B-26 production winding down, was moving fast, and, indeed, got its R-4360-powered XBTM-1 flying by late August 1944. Martin’s plane, named the Mauler, had thus far achieved impressive performance—a maximum speed of 367 mph combined with the ability to lift a phenomenal payload of 8,500 pounds—but also exhibited unacceptable handling characteristics that would oblige the company to return it to the factory for time-consuming modifications. Even with its flaws, BuAer gave Martin a war-time order for 750 BTM-1s in hopes the major problems could be resolved before the plane was actually tooled for production.

The Mauler’s delays gave Douglas exactly what it needed most—a little more time. On March 19, 1945—almost nine months to the day from Heinemann’s meeting in Washington—the first XBT2D-1 (shown below) lifted off the runway at El Segundo.

Such was the rush that the plane had flown with landing gear struts and wheels borrowed from a Vought Corsair and an older version of the R-3350 engine that didn’t produce the specified power. Even so, the XBT2D-1’s basic design proved to be excellent in every way: Empty weight was 10,093 pounds (4,200 pounds less than Martin’s XBTM-1), maximum payload was 7,400 pounds (73 percent of empty weight compared to the XBTM-1’s 59 percent) and flight trials indicated above-average handling qualities. Its 374 mph top speed was similar, but more notably, the XBT2D-1 was less complex overall, and thus cheaper to build and easier to maintain. Two months after the plane flew, BuAer was sufficiently impressed with Douglas’ efforts to award a wartime order for 548 BT2D-1s. The Curtiss XBTC-1 and the Kaiser-Fleetwings XBTK-1 both flew in the spring of 1945, but no orders were forthcoming. Heinemann’s gambit had so far paid off.

The XBT2D-1 was to become world-famous as the Douglas A-1 Skyraider. It would remain in production until 1957, with well over 3,000 being built, and would see active service into the 1970's - long after all other propeller-driven strike aircraft had been retired. Not bad for a World War II-vintage design!

The Skyraider could carry up to 8,000 pounds of ordnance on 15 external hardpoints, including bombs, torpedoes and rockets, and had four 20mm. cannon mounted in the wings. Its maximum speed of 320 mph was slow in the jet age, but proved a real advantage in close air support, where it could get ‘low and slow’ to survey the battlefield in a way that faster jets simply could not. In addition, its well-armored structure proved able to absorb damage that would have destroyed many jet aircraft. It became beloved of its pilots in every war in which it fought.

As US Marine Corps Captain William C. Smith (who flew the AD-1 Skyraider in Korea) later observed:

When you fly combat, you need to have confidence in your airplane, and after that first week there was no question in my mind that our AD’s were the best planes in the world for the job expected of us, whether we were told to take out targets like rail yards or bridges or to provide close air support right down on the deck in front of the battle lines . . . Even after all these years of progress, I believe the AD is still the best airplane ever made for [the] close-in attack option - better, in fact, than anything flying today.

Skyraider with extended fuselage dive brakes

The story of the Skyraider is well-known, and I won’t repeat it in detail here. More information can be found in the Wikipedia entry on the aircraft, and in this very informative article. Suffice it to say that the Skyraider served the US Navy in Korea and Vietnam, where it also flew with the USAF; flew with the South Vietnamese Air Force; served France in the Algerian war, the surviving French aircraft subsequently being passed to Gabon and Chad; and proved very successful in every theater of operation.

The base aircraft was developed into the AD-4W airborne early warning radar aircraft for the US Navy:

and into the EA-1F electronic warfare platform:

Some Skyraiders were even equipped with ‘buddy store’ refueling packs, to offer fuel to other aircraft in the tanker role.

A turboprop version of the A-1 was developed by Douglas, the A2D Skyshark.

However, the changes required were so drastic that the Skyshark turned into a completely different aircraft. Twelve pre-production models were built, but the program was canceled in 1954.

Perhaps the greatest compliment paid to the A-1 Skyraider was the subsequent development of the A-10 Thunderbolt II attack aircraft.

Pierre Sprey, who developed the specifications for the A-10, spoke with many pilots with experience in Vietnam. From this, he understood that an effective close support aircraft had to be well-protected against ground fire, and slow-moving, so that its pilot could see his targets clearly and have time to maneuver his aircraft to hit them. The jet 'fast-movers' in Vietnam had all too often been unable to do so. In a very real sense, therefore, the A-10 is the Skyraider's ultimate progeny.

Although long withdrawn from service, some Skyraiders fly on in civilian ownership, such as this one operated by the Museum of Flying in Santa Monica, CA (shown here accompanied by a North American T-28 Trojan trainer).

So, the 1943 cogitation of US Navy planners produced what was probably the finest propeller-driven strike aircraft of all time in the Douglas A-1 Skyraider; a flawed but nevertheless impressive heavy strike aircraft, the Martin AM-1 Mauler; and the best-performing do-it-all propeller-driven fighter-bomber of all time, the Boeing XF8, even though, through no fault of its own, this was never taken into production. Not a bad effort!



Anonymous said...


Excellent writing. My father-in-law flew SBD's for the Marine Corp in WWII. He liked the fact you could dive almost vertically on target; this made it a very small target. His only problem was in warm South Pacific air they would fly away from the target if it was less than 50 miles away to gain enough altitude and then reverse course to attack. The poor old SBD couldn't climb with much of a bomb load.

The Helldiver was a bit faster but could not dive at the same steep angle of attack. In his mind, the SBD was a much better aircraft.

Many of the folks in his squadron, including him, transitioned into FU-8 Corsairs. The Corsair was a very stable platform but did not have the same bomb release mechanism that swung the bomb out and under the prop.

My father in law said many of the pilots came back to base after bombing runs at steep angles with bent propellers.


Wayne Conrad said...

Outstanding bit of writing, but now I have to work later to make up for it--I forgot where I was and just kept reading, oblivious of the time and place. Beautiful plane to end on. Thanks.

Shell said...

I've been a fan of the Spad since I first read of it as a boy while the Vietnam War was still going on. Imagine, a prop-driven aircraft kicking ass and taking names in the Jet Age!

I've been a fan of the Warthog since my high school days when I read of it while a student in AFJROTC. A jet that flies "low and slow" in direct contravention of the jet-jockey mantra "Speed Is Life"? Who'd'a thunk it? I first saw it fly during REFORGER in 1981, while I was toiling as a grunt for Uncle's Army. Some Warthog pilots put on a little maneuverability airshow over us after their part in the exercise was done.

So ugly it was beautiful, a machine perfectly designed for the job it was required to do, but just not sexy enough for the Air Force to keep it despite its success. Too bad the perception and prejudice of a few stars beats the reality known to and appreciated by stripes (and slick sleeves).

Shell said...

Meant to say that the, Commemorative Air Force has a Wing nearby with an AT-6 Texan they offer rides in. I plan to take one of those rides and pretend that I'm in a Skyraider.

Anonymous said...

Peter, excellent story. Thanks for putting it together.

Throughout my flying years, I strove to fly an AD (Skyraider). Never quite made it. I did get a couple hundred hours in the T-28, but I never got to fly the tail-dragger.

I suggest to you that a better follow-on for the AD is the A-4 Skyhawk rather than the A-10, made by a different company. Heineman's Skyhawk carried many of the attributes of the AD, but was polluted by the need to carry nukes. Nonetheless, the A-4 was an excellent light attack aircraft for the jet age. It also was not a bad jet in a dogfight, even though it lacked the pedigree for such.

Bottom line: Thanks for the memories.


Brandon said...

Excellent article, Peter. Well done, indeed.

Anonymous said...

An absolutely excellent posting. Thanks for the effort. I watched Spads work out in 'Nam. Awesome planes and pilots.

Anonymous said...

Everything I have ever seen or read about the Martin AM-1 Mauler listed the 4360 as the powerplant never the 3350.

Unknown said...


It is remiss of me to have left this article unread for so long but I am glad I did. I do have to correct you on one comment though, namely:

"As a fighter, the XF8 had a comparable practical (as opposed to theoretical) service ceiling, was more heavily armed (in its 20mm. cannon-equipped version), and was as fast or faster than, any piston-engined fighter of any World War II power,"

Using Wikipedia as a reference, the XF8B-1 has a quoted maximum speed of 376knots (432mph / 695km/h).

Compare that speed to the Dornier Do 335A1 fighter, employed in very limited numbers by the Luftwaffe at the end of World War II which had a quoted maximum speed of 474mph (765km/h).

The 'Pfeil' (Arrow) as the Do 335 was known is probably one of the most revolutionary non-jet propelled designs to come out of WW2 and one that could have made a potentially significant difference to the outcome or, at a minimum, the duration of the war had it not become yet another victim of Germany's overbloated, contradictory and often politically influenced military procurement system.

Peter said...

@Sven: Yes, the Do 335 was the fastest piston-engined fighter of the war: but it served in extraordinarily limited numbers for a very limited time, and only in Europe. It can't really be considered an operational aircraft, in that sense. The XF8B-1 was comparable or superior to any other US or Japanese fighter in the Pacific theater of operations, which was its focus: hence my claim for it. Perhaps I should have specified the theater.