GAX Ground Attack Experimental (1920-1923) Program

[Dynoman]

Following WWI, Air Corps planners saw the need for a ground attack aircraft, which was armored and carried a 37 mm cannon and eight .30 caliber machine guns. This resulted in the GA-1. Six aircraft were built:

1. Boeing GA-1 (1920)
2. Orenco IL-1 (1921) (Also known as a Model E)
3. Junkers JL-12 (1921)
4. Gallaudet DB-1 (1921)
5. Boeing GA-2 (1922)
6. Aeromarine PG-1 (1923)

 

[Dynoman]

Boeing GA-1 (GAX-1)

 

[ACResearcher]

The GAX aircraft were apparently absolutely dreadful to fly. Somewhere in my documents I have a note saying that when a pilot at Dayton had gotten on someone's "s... list" he was assigned to fly the GA for a while. That appears to have gotten that pilot back on the straight-and-narrow.

AlanG

 

[Dynoman]

Alan, that is a funny story. Everything I've read about all of the aircraft from the program so far indicated that all of them lack performance, primarily due to the armor and weight of the armament.

Some interesting things resulted from the program, like the J.L.12, which had fittings for 30 Thompson machine guns.

 

[Dynoman]

Gallaudet DB-1 aircraft and cockpit

 

[hesham]

Amazing work my dear Dynoman.

 

[Dynoman]

Thank you Hesham. A few of these aircraft are represented in SPF, however they are not presented in the context of the GAX program where they were conceived and evaluated for their air-to-ground role.

The Boeing GA-2:

 

[Dynoman]

Aeromarine Plane and Motor Co. entry into the GAX program: PG-1

 

[Dynoman]

Orenco IL-1 (Orenco Model E).

The IL-1 was a two-place open cockpit biplane, with a 400 hp Liberty 12 engine, with a span of 46 feet 0 inches and a length of 32 feet 0 inches. They were registered as AS63273/AS63274 and designated P-147 and P-168 as part of the McCook Field GAX program. Picture Courtesy of Jos Heyman's United States Military Aircraft.

 

[Dynoman]

The GAX program began in earnest after the Army recognized that the Germans of WWI (i.e. the special units known as the Schlachstaffeln) had effectively employed aircraft in ground attack roles to assist their infantry. Their effectiveness, particularly against troops fighting from the trenches, resulted in the US Army to conduct an experiment in September of 1919 using a modified Glenn Martin Bomber, known as the Glenn Martin Cannon (GMC) with a 37mm cannon mounted to the forward cockpit. The results of these tests led the Army to issue a circular proposal for industry to develop an armored attack aircraft on October 15, 1919. Unfortunately, no one responded. This led to the Engineering Division of McCook Field to design and develop their own attack aircraft, which was known as the GAX-1.

 

[ACResearcher]

In a February 9, 1924 letter from the Air Service, Engineering Division, Office of the Chief of Division, McCook Field, to the Chief of Air Services, Washington, DC, details on a test of the GA-2 airplane No. P-310 were shared.

More important than the facts and figures of these test results was the following in the body of the letter:

"...in view of the adverse criticism of the pilots who fly this machine and the universal sentiment that it is loggy, hard to control and hard to maneuver, although it is well balanced, it s not thought advisable to spend more time and money in trying to improve this type."

On top of that, the fuel capacity of the aircraft was so low that it was recommended the aircraft be shipped via freight to the Attack Group to use for study of what design aspects were desirable in future attack aircraft.

I've been researching Attack aircraft for a number of years, and the GA-1 and GA-2 are two of my favorite lumbering behemoths.

AlanG

 

[Silencer1]

Nice thread!

Curiously, in the excellent book, covering almost all American attack aircraft - "American Attack Aircraft Since 1926" written by E.R. Johnson, GAX programm' aircraft only mentioned once, and didn't described and illustrated.
https://books.google.fr/books?id=GmFhOCYckfQC&pg=PA3&hl=fr&source=gbs_toc_r&cad=3#v=onepage&q&f=true

In my humble opinion, these aircraft deserve more attention by the author, as first and large-scale programm, aimed to design armoured attacker.

 

[Dynoman]

ACResearcher, it appears that all of the GAX aircraft were poor performers:

In the case of the last GAX aircraft design, the Aeromarine PG-1:

"After a test cannon-engine was produced in July 1920, bids for the PG-l were requested from private firms. Four submitted bids, and Aeromarine, at Keyport, New Jersey, received the order on March 15, 1921, for three prototypes. The first was delivered as a static test airframe on November 28, 1921, for static tests and the second was flown on July 14, 1922, with a Wright H, which failed on takeoff, destroying the aircraft. A 346-hp Packard 1237 was used on the third prototype, tested in 1923. Its top speed of 116 mph at 3,342 pounds gross weight was below that expected of the original configuration, as shown in the accompanying data."
http://www.americancombatplanes.com/biplane_army_3.html

I agree with you Silencer1, the GAX program deserves more attention as the GAX aircraft displayed a shift following the GAX program away from the belief that attack aircraft should be armored and instead a better design would be to use lighter conventional aircraft construction techniques, while armoring various areas of the aircraft (e.g. the cockpit) and redesign systems (e.g. increased system redundancy, later self sealing tanks, etc.) that were particularly vulnerable to gun fire. It would be a few years later until the first US attack aircraft (a modified Curtiss O-1B), the Curtiss A-3 Falcon emerged having won a fly-off competition against the Douglas A-2.

 

[Dynoman]

GAX was also known as the 'Sawmill.' The GAX and GA-1 flew at Kelly Field with the newly formed 3rd Attack Group to prove the concept of ground attack aircraft.

 

[Dynoman]

GAX cartoon from McCook Field's newsletter (Slipstream) 1920. The aircraft that can do anything. They certainly placed a lot of hope in the heavy triplane.