I highly suggest you read the seven volumes of The Army Air Forces in World War II.

I wrote an extremely extensive post about how the draft worked in the United States during World War II here, and I’ll reproduce the relevant parts below.

The formation of the independent military service known today as the United States Air Force is complicated, and requires further examination. During the majority of World War I, aviation units in the U.S. Army operated under the Aviation Section of the Signal Corps, which was disbanded on May 20, 1918 and replaced on May 24 with the United States Army Air Service. On July 2, 1926, the Army Air Service was renamed the Air Corps. On March 1, 1935, General Headquarters Air Force was activated. On paper, it was an equal entity to the Air Corps. GHQ Air Force controlled the tactical elements of the Air Corps and reported to the Adjutant General, while members of the tactical units served in the Air Corps, which was responsible for a large number of procurement and supply functions.

On June 20, 1941, the Army Air Forces were established; GHQ Air Force became the Air Force Combat Command. The Marshall Reorganizations of March 1942 (paced by Executive Order 9082 of February 28, 1942) united the Army and created three separate major commands, preserving the integrity of the Army Air Forces. The Air Corps ceased to be a command and control element on March 9, 1942, and reverted to combat arm status; in May 1945, 88% of officers and 82% of enlisted men serving in the Army Air Forces were assigned to the Air Corps.

• Army Ground Forces

• Antiaircraft Command (pseudo-arm)

• Armored Force (pseudo-arm)

• Cavalry

• Coast Artillery

• Field Artillery

• Infantry

• Tank Destroyer Force (pseudo-arm)

• Army Air Forces

• Air Corps

• Army Service Forces

• Chemical Warfare Service

• Corps of Engineers

• Medical Department

• Ordnance Department

• Quartermaster Corps

• Signal Corps

• Transportation Corps

By the end of the war, the Army Air Forces had grown independent from the rest of the Army, and the National Security Act of 1947 created a separate Department of the Air Force. The modern-day United States Air Force traces its formation to September 18, 1947, when its first Secretary, W. Stuart Symington, was sworn in.

Before the re-establishment of the draft in the United States in September 1940, the Air Corps received prospective pilot candidates through voluntary enlistment. Many had previously flown planes or had knowledge of the principles of flight. For appointment as a flying cadet, a man was

required to submit to the recruiting officer...a properly filled out application form, supported by three letters of recommendation from citizens of prominence in his place of domicile, legal evidence of his place and date of birth, and a registrar's certificate of college or university credits. Those who did not have the two-year college background had to pass a difficult examination prepared and graded by the department of ground training at Randolph Field....grading the papers was slow and delays were inevitable. When these details were out of the way, the next step was for the candidate to appear before a[n]...examining board. The applications...were then forwarded through recruiting channels to the OCAC [Office, Chief of the Air Corps] which made a recommendation to The Adjutant General. Those applicants favorably recommended were appointed flying cadets by the War Department. Those who received appointments were then ordered by their corps area commander to report at the Air Corps Training Center on a given date to start training.

Men had to also have demonstrated proof of citizenship 10 years before the date of application and be between the ages of 20 and 26. Physical standards were also strict; 73.2% of volunteers failed the medical exam in 1939, but an increase in the granting of waivers (the standards themselves were not reduced) meant that the failure rate was only 50.3% in 1941.

In peacetime, the order of precedence for appointment as a flying cadet was as follows;

• a. (1) Graduates of the United States Military Academy, the United States Naval Academy, and the United States Coast Guard Academy who apply for appointment as flying cadets within year from date of graduation, who fail to receive commissions because of lack of vacancies and are recommended for appointment as flying cadets by the respective superintendents of those academies.

• a. (2) Enlisted men of the Air Corps of the Regular Army who at time of appointment have served at least 11 months.

• b. Other enlisted men of the Regular Army who at time of appointment have served at least 11 months.

• c. Officers and enlisted men of the National Guard who at time of appointment have been assigned to Air Corps units for at least 11 months and who are favorably recommended by their commanding officers.

• d. College graduates who are graduates of the Air Corps Reserve Officers' Training Corps units.

• e. College graduates who are graduates of Reserve Officers' Training Corps units of other arms or services.

• f. Graduates of recognized colleges and universities.

• g. Other officers and enlisted men of the National Guard who at time of appointment have had at least 11 months' service.

• h. Students in Air Corps Reserve Officers' Training Corps units who have completed their junior year.

• i.Reserve officers and members of the Enlisted Reserve Corps who at time of appointment have served at least 11 months.

• j. Students in good standing of recognized universities who have completed their sophomore year.

• k Others.

Men who were eliminated along the way could also apply for training in ground specialties of the Air Corps. Education requirements were even stricter;

In engineering, the requirement was a degree...or senior standing in an engineering school; in communications, a...degree with credits in electricity or radio; in armament, where eliminees were to be the exclusive source, a...degree and a special recommendation...by the commanding officer of the previous training detachment; and in photography, a...degree with course work in either geology or chemistry.

In summer 1940, legislation that limited the number of flying cadets trained in any one year to 2,500 was suspended. On June 3, 1941, the name "aviation cadet" was substituted for "flying cadet," and this rank was brought equal in pay, allowances, and insurance with the one already existing in the Navy and Marine Corps. The Air Corps initially refused to abandon the two-year college requirement when pressured. On June 3, other legislation allowed the training of pilots who were qualified as sergeants; 20% of all pilots were to be so trained. The requirements were less than that of aviation cadets; “aviation students” had to have graduated in the top half of their class in high school with at least 1 1/2 credits of mathematics, and be between the ages of 18 and 22. An aviation cadet qualifying exam replaced the two-year college requirement in January 1942. Also in January, the age bracket for aviation cadets was lowered to 18 years old; 18 year olds were not liable to be drafted until November 1942, and had to be acquired via voluntary enlistment until then.

With the draft in effect, men could choose to volunteer for service in the Air Corps both before or after induction. Men earmarked for the Air Corps were sent to such facilities from assigned reception centers generally closest to their place of residence or induction. The Air Corps, as a result, began to receive a large number of its aviation cadets from purely military sources. An Air Corps class graduating on December 20, 1941, broke down as follows:

Men	Percentage
Aviation cadets assigned directly from civilian life	63%
Enlisted men assigned to training as aviation cadets	27%
Enlisted men assigned to training as aviation students	8%
Regular Army officers and officers of the Army of the United States assigned to flying training	2%

To the advantage of the service, draft boards often gave lists of men classified as I-A to the Air Corps, who then targeted them for recruitment. The Air Corps also promoted itself as a glamorous assignment, especially on college campuses, and a large number of men who voluntarily enlisted or chose their branch of service after being drafted picked it; in 1943, 41% of men who fell into the top two classes in the Army General Classification Test chose at some point to volunteer for the Air Corps.

Both the draft and voluntary enlistment caused the Air Corps to construct large numbers of new facilities. Replacement training centers (later called basic training centers) and classification centers were established at various locations throughout the United States, principally where the weather allowed year-round flying. The locations of these facilities can be found throughout volume VI of The Army Air Forces in World War II.

Source:

Cate, James L., Wesley Frank Craven The Army Air Forces in World War II Vol. VI: Men and Planes. Chicago: University of Chicago Press, 1955.

First thing you'll need to know is that the USAF didn't exist in 1941. In fact, it didn't become an independent service until 1947. It was known as the US Army Air Corps from July 1926 until June 1941, then US Army Air Forces from June 1941 to 1947.