WHAT WOULD BECOME AMERICA'S GREATEST TWIN-ENGINE PROPELLER-DRIVEN ATTACK AIRCRAFT WAS DELAYED INTO COMBAT INTRODUCTION by way of UNREASONABLE DEMANDS FROM THE ARMY AIR FORCE AND FROM THE BUILDER During 1940 with a pretty large portion of the world all ready at war.

WHAT WOULD BECOME AMERICA'S GREATEST TWIN-ENGINE PROPELLER-DRIVEN ATTACK AIRCRAFT WAS DELAYED INTO COMBAT INTRODUCTION by way of UNREASONABLE DEMANDS FROM THE ARMY AIR FORCE AND FROM THE BUILDER

During 1940 with a pretty large portion of the world all ready at war, the United States Army Air Corps was able to field the beginnings of a recently made known force of combat aircraft which included the Douglas A-20 Havoc, the Martin B-- 26 Marauder, and the North American B-25 Mitchell. However, it must be remembered that, during this trying time period, aeronautical devel opment was rapidly advancing - not like today where it can be ten years from the start of a combat aircraft's design to the prototype's first flight.

Accordingly, Douglas Aircraft Corporation in southern California, began studies for a more advanced aircraft that could work for as a replacement for all three of the strange aircraft. Lessons were rapidly being learned from the air war above Europe - the Havoc, portrayed by the DB-7 export variant (known as Boston in RAF service), was not really well-suited for this emblem of combat since the single pilot was not reachable in flight by the agency of other members of the company the defensive armament was not adequate against the onslaught of Luftwaffe fighters, and certain structural constituents of the overall design were not suited to combat. However, the application of mind and development of the fresh design would lead to self-same major problems for Douglas including a Congressional investigation.

Douglas designer Edward H Heinemann (whose career with the company was, in the expressions of longevity and creativity, just beginning) traveled to Wright Field in late 1940 to hear Army ideas forward what an ideal replace, ment for the Havoc should be. At the time, the Army was enamored with the idea of an aircraft lugging a excessively heavy cannon - up to 75mm - aloft in this way that it could blast enemy mould targets. Some Army and Douglas personnel felt that the A-20 could be upgraded to carry the imposing weapon yet Heinemann (who held the patent forward the A-20 design) knew that the fuselage was just too narrow to accommodate the weapon, its ammunition, and operator.

Oddly it be seens that the Army did not have any really solid specification for the of recent origin design and they were apparPART I

ently "testing the water" to diocese what Douglas could come up with. A bit of a guideline was issued in a 5 November 1940 message to Douglas from Major Frank Carroll who ran the Air Corps' Experimental Section at Wright Field. The major summ up what was already being learned in Europe:

1) No interchangeability of set This is generally considered the greatest in number serious defect of all.

2) Insufficient defensive armament. fire-arms should be in power minarets for all-around defense. Browning .50-caliber fire-arms preferable, if not mandatory, while ammunition supplies should also be increased.

3) The design solidity of 6 G ultimate - which is reduc to 55 G when the gros weight is increased with modernization - is too little for safety in the maneuvers now contemplated. Shallow glide bombing will be attempted with the A-20, further there is no possibility of accompushing a moderate form of dive bomber attack which the Chief of the Air Corps has repeatedly beseeched for this type.

4) Landing and takeoff distances are considered too great for a finish support design, which is required to operate from relatively unimproved fields within 100 miles of the territory forces.

5) Speed now considered thoroughly good for this size and representation but it will probably have to be increased for airplanes to be produc in 1942-43 particularly the spe at intermediate altitude.

Armed with these suggestions and with the Army's desire for an airborne cannon, Heinemann and his colleagues got busy to create a "paper" airplane that would satisfy the Army. There was often to consider including how to make a fresh aircraft much stronger without it getting frequently heavier. There were also questions as to streamlining and for what cause the aircraft should be configured. However, there was no doubt that from the self-same start the new craft would use the superlative Pratt & Whitney R-- 2800 radial for power.

Heinemann take counseled with friends at the National Advisory Committee for Aeronautics (NACA) for suggestions. NACA, at the time, was instrumental in creating aerodynamic advancements and had done considerable research into the cowling of large radial engines. Efficient cowling would not solitary benefit cooling but would also add to streamlining and an increase in overall performance. NACA had also done in-depth research into airfoils and they make acceptableed that Heinemann utilize a lamroar proceed airfoil which, while offering a greater increase in spe than other airfoils, would also require extremely bring to a period production tolerances in order to achieve the desired meanings

Given that Heinemann knew he would be using the R-2800 and with a cragged idea of the size of the aircraft in his head, he knew particular attention would have to be .paid to the nacelles which would be quite large since they also would house the landing gear. Passing near of his initial concepts to NACA, head mechanical engineer Elton Miller quickly replied, "With relation to the length of the nacelle, it appeared that the duration was determined by the position of the screws with reference to the pilot's cockpit and the personnel quarters in the fuselage and through the space needed for retracting the landing gear. It did not appear possible to make it any shorter for practical reasons and nobody put in mind ofed making it any longer. It was the general opinion that the drag of the nacelle would hang largely on the skin friction and, more especially, onward the number of scoops and protuberances in succession the surface."