The recent resurgence of questions about the mysterious "gap" in the the post-1962 attack plane designation scheme (at A-11) leads me to repost this summary of American attack planes. Some of the confusion is due to the fact that there were TWO separate and distinct A-for-attack series of aircraft, one used by the Army in the years 1926-1948, and the other used by all the services in the years after 1962.
The Army introduced the A designation category in 1926. It applied to attack and light bombardment categories of combat aircraft.
This is the original A-series, which covered the years 1926-1948:
A-1 Not assigned, since it clashed with th
Cox-Klemm XA-1, an ambulance plane still in service.
Douglas XA-2 Conversion of O-2 two-seat observation biplane
to attack configuration. Lost out to Curtiss A-3
in attack plane competition. Only one built.
Curtiss A-3 Falcon O-1B observation plane adapted to attack role
by addition of bomb racks and additional 0.30
cal gun in each lower wing. 144 built.
Curtiss XA-4 Falcon A-3 modified to test 440hp P & W R-1340 Wasp
radial engine. Only one built.
Curtiss XA-5 Attack counterpart of XO-16 two-seat observation
biplane. Canceled before any could be
delivered.
Curtiss XA-6 Attack counterpart of XO-18 two-seat observation
biplane. Cancelled before any could be
delivered.
General Aviation Two-seat low-wing monoplane ground attack plane.
(Fokker) XA-7 Lost out to Curtiss A-8 for production orders.
Curtiss YA-8 Two-seat monoplane ground attack aircraft. One
8 built.
Lockheed YA-9 Two-seat monoplane attack aircraft. Attack
version of Lockheed YP-24 experimental pursuit
aircraft. Parent company (Detroit Aircraft) went belly-up and
none were produced.
Curtiss YA-10 First YA-8 reequipped with a 625 hp P&W Hornet
radial engine. 175 mph. Proved that radial
engine was preferable to liquid-cooled engine
for attack role, and convinced Army to have A-8B
aircraft on order be produced as A-12.
Consolidated A-11 Development of Lockheed YA-9. Two-seat
monoplane attack aircraft. Performance was
well advanced over its contemporaries, but the
Army disliked liquid-cooled engines for ground
attack planes. Pursuit versions were P-30 and
PB-2A.
Curtiss A-12 Shrike Two-seat monoplane attack aircraft. Adaptation
of A-8 design to 690 hp Wright R-1820 Cyclone
radial engine. Forty-six A-12s built for
U. S. Army. 20 export versions sent to China.
Northrop XA-13 Two-seat monoplane attack aircraft.
Extensively modified version of Gamma 2C
commercial monoplane.
Curtiss XA-14 Two-seat, twin-engined ground attack aircraft.
Only one built.
Martin XA-15 Attack version of Martin YB-10 bomber.
Abandoned in design stage in favor of Curtiss
XA-14.
Northrop XA-16 XA-13 fitted with 950 hp P&W R-1830-7 radial.
Only one built. Test results indicated that the
aircraft was overpowered and that production
aircraft should have either a smaller engine
or larger tail.
Northrop A-17 Two-seat, single-engine attack aircraft. One
P&W R-1535 radial engine. A-17 had fixed
landing gear, A-17A had retractable landing
gear. Numerous exports.
Curtiss Y1A-18 Shrike Two-seat, twin-engined ground attack aircraft.
Same armament as XA-1, but bombs were
carried in wing bays rather than in fuselage.
13 built. Used primarily for operational
training.
Vultee YA-19 Two-seat attack aircraft. Evolved from V-11GB
export attack aircraft. Five built.
Douglas A-20 Havoc Twin engine, three-seat attack bomber
Most widely-used aircraft in the A series.
Produced in many different versions with many
different armament schemes. 7478 built.
F-3 was photo recon version.
P-70 was night-fighter adaptation equipped with
radar.
Stearman XA-21 Three-seat, twin-engine light bomber. No production orders.
Only one built.
Martin A-22 Maryland Twin engine, three-seat attack aircraft.
Lost out to Douglas A-20 for Army production
orders, but ordered by French. Flew in combat
during German invasion. After French collapse,
remaining Marylands were taken over by British.
Served with British units in Mediterranean and
North Africa. Some service with Vichy French.
Martin A-23 Proposal for twin-engine attack aircraft powered
by Wright R-3350 radials. Project was dropped.
Douglas A-24 Dauntless Army version of SDB Dauntless carrier-based
dive bomber. A-24 was similar to Navy SBD except for
removal of deck landing gear and a new tail
wheel. 953 built. First examples entered
Army service in 1941. Most A-24s remained
Stateside, where they were used primarily for
training, but some did see combat.
Curtiss A-25 Shrike Army version of SB2C-1 Helldiver carrier-
based dive bomber. 900 delivered to US Army.
Army eventually decided that it didn't need
dive bombers, and A-25 never entered combat.
Most used as trainers and target tugs. Ten were
delivered to Australia. 410 were turned over
to the US Marine Corps, which used them as
operational trainers under the designation
SB2C-1A.
Douglas A-26 Invader Three-seat, twin-engine light bomber.
Regarded as USAAF's best twin-engine bomber at
end of WW2, and plans were under way to convert
all A-20, B-25, and B-26 units to the A-26 at
war's end.
B-26 saw lots of action in Korean War in armed
reconnaissance and interdiction role.
Withdrawn from front-line service with USAF
in mid-1950s and replaced by B-57 and R/B-66.
Many Invaders were sold as surplus on the
civilian market, and converted to executive
transports.
Many were exported to foreign air forces. Some
are still in service.
North American A-27 Designation for 10 NA-69 export attack planes
ordered by Thailand, but siezed by Army lest
they fall into Japanese hands.
Used only for training.
Lockheed A-28 Hudson Hudson was military adaptation of Model 14
commercial airliner designed to British
requirements. Nearly 2000 Hudsons were
acquired by British, either by direct purchase
or via Lend-Lease. After Lend-Lease was
approved in 1941, outstanding British contracts
for Hudsons (and other aircraft as well) were
taken over under Army contracts and produced
under USAAF designations and serial numbers.
Most went directly to British Commonwealth air
forces, and never served with USAAF.
Lockheed A-29 Hudson Designation given to Hudson light bomber ordered
under Lend-Lease for service with British
Commonwealth forces. Differed from A-28 in
being powered by two Wright R-1820 Cyclone
radials. Most went directly to Commonwealth
air forces and never served with USAAF.
Martin A-30 Baltimore Twin-engine attack bomber built for British use
under Lend-Lease. Served exclusively in the
Mediterranean area with British, South African,
Greek and Italian Co-belligerent air forces.
None used operationally by USAAF. 1575 built.
Vultee A-31 Vengeance Two-seat, single-engined dive bomber. One
Most were sent to the British under Lend-Lease.
Vengeances in US service used
primarily for training and never saw combat.
Brewster XA-32 Single-seat attack bomber. Speed and range performance fell
below expectation. Project cancelled.
Douglas A-33 Designation for 31 Douglas 8A-5 attack planes
taken over from Peruvian order.
Used for general utility service. Never saw
any combat.
Brewster A-34 Bermuda Designation assigned for Lend-Lease
documentation to SB2A Buccaneer naval dive
bomber. None ever served with AAF.
Vultee A-35 Vengeance Two-seat, single-engined dive bomber.
Modification of A-31 with four fixed 0.50 cal
guns in wing, one 0.50 cal gun in rear cockpit.
Most sent to the British and the
Australians. Some given to Free French.
Never saw combat in USAAF service, serving only
in training and target-towing roles.
North American A-36 Mustang Dive bomber version of P-51 Mustang fighter.
First version of Mustang to see action in USAAF
service.
Saw action primarily on Italian front and in
India.
Hughes XA-37 Twin-boom, twin-engined light bomber project.
Most of airframe constructed of Duramold, a
material made of heat-bonded wood and plastic.
Carried no armament.
USAAF considered it as a bomber escort, as a
fighter, and as an attack aircraft. In its
fighter incarnation, it seems to have had the
designation "XP-73" reserved for it. The
designation "XA-37" refers to its attack
incarnation.
Beechcraft XA-38 Destroyer Two-seat attack bomber. Two Wright R-3350
radials. Delayed by lack of
availability of engines, which were needed by
B-29. Never reached production.
Kaiser-Fleetwings XA-39 Single seat, single-engined light bomber.
One P&W R-2800 radial.
Never got past the mockup stage.
Curtiss XA-40 Single seat, single-engined light bomber.
One Wright R-3350 radial.
Never got past the mockup stage.
Convair XA-41 Single seat, single engine close-support
aircraft. One P&W R-4360 radial. Four 37-mm
cannon and four 0.50 cal guns in the wings.
Internal bomb bay could carry 3000 lbs of
bombs. Flight tests showed promise, but
Army close support was well provided for by P-47
Thunderbolt and A-26 Invader. No production
orders. Only one built.
Douglas XA-42 Proposal for twin-engine attack aircraft powered
by two Allison V-1710 liquid cooled engines
mounted in fuselage and driving two contra-
rotating props in tail. Design
showed greater potential as a medium bomber and
was redesignated XB-42
Curtiss XA-43 Proposal for two seat, four jet attack plane.
Project cancelled in early design stage. Funds
and serial numbers transferred to similarly-
configured XP-87 Blackhawk night fighter.
Convair XA-44 Tactical bomber with three 4000 lb. st. General
Electric J-35 turbojets buried in the fuselage
and fed by two lateral intakes. 30-degree
swept-forward wing. Redesignated XB-53 in 1948.
Cancelled before any could be built.
Martin XA-45 Three-jet light tactical bomber. Redesignated
XB-51 in 1948.
[The original A series ends at this point.]
In 1948, the separate A category was eliminated from the Air Force designation scheme. Henceforth, all future Air Force planes that fell under the attack category were to be classified under B (for bomber). At that time, only two aircraft from the original attack series still remained in service with the Air Force--the Douglas A-26 Invader and the Douglas A-24 Dauntless. The Invader was redesignated B-26. There was no danger of confusion with the Martin B-26 Marauder, since all Marauders had been removed from active service by that time. So there were TWO airplanes that carried the B-26 designation, but they didn't both serve at the same time! In addition, the few Douglas A-24s still serving with the USAF in 1948 were redesignated F-24, a fighter category. Again, there was no possibility of confusion, because the prior P-24 designation had been carried by a Lockeed design of the early 1930s which never attained quantity production.
1962 Unified Designation Scheme
Prior to 1962, the US Navy had its own separate designation scheme for its attack aircraft. In 1962, Secretary of Defense Robert McNamara decided to unify the aircraft designation schemes of all the services under one umbrella. In addition, the A for attack category (which had been eliminated in 1948) was reintroduced. The Air Force initially had no aircraft that fell into the A category, but the Navy did have some and all of these were duly redesignated. In later years, the Air Force did acquire some attack aircraft, and these were assigned numbers in the A series in the sequence in which they were ordered into service.
The attack planes in the post-1962 A-category are:
Douglas A-1 Skyraider Formerly designated AD. Single-engine,
carrier-based attack aircraft. One Wright
R-3350 radial. 322 mph at 15,000 ft.
Four 20-mm cannon in wings, underwing load of
up to 10,000 pounds of bombs. Night-attack,
antisubmarine warfare, ambulance, cargo,
and radar picket versions built. Also served
with USAF, Royal Navy, France, Vietnam.
Served in Korean, Algerian, and Vietnam wars.
Total of 3180 built.
North American A-2 Savage Formerly designated AJ. Three-engined carrier-
based strategic bomber. Two 2300 hp P&W
R-2800-44W radials in underwing nacelles,
one Allison J33-A-10 turbojet of 4600 lb. st
in rear fuselage.
Most Savages did not serve in their intended
roles as strategic bombers, but were converted
as flight-refuelling tankers.
Douglas A-3 Skywarrior Formerly designated A3D. Twin-jet, swept-wing
carrier-based strategic bombing aircraft. Two
P&W J57-P-6A turbojets. Many converted to
aerial tankers, electronic countermeasures
planes, and trainers. Total of 284 built.
Douglas A-4 Skyhawk Formerly designated A4D. Single-engine carrier-
based attack aircraft. Versions A through D
powered by Wright J-65 jet. E version powered
by P & W J-52 jet.
Extensive service with US Navy during Vietnam
War. Served with IAF during "War of Attrition"
and Yom Kippur War. Served with Argentina
during Falklands/Malvinas campaign. Also
delivered to New Zealand, Singapore, and Kuwait.
2960 built.
North American A-5 Vigilante Formerly designated A3J. Twin-engine, two seat
carrier-based supersonic strategic bomber and
reconnaissance aircraft.
In 1964, it was decided that Navy strategic role
would in the future be pursued exclusively by
Polaris-armed nuclear submarines and not by
aircraft. Remaining A-5s were all converted
to RA-5C reconnaissance configuration.
Total of 156 Vigilantes built.
Grumman A-6 Intruder Formerly designated A2F. Twin engine, two seat
carrier-based all-weather attack aircraft.
Two P&W J-52 turbojets mounted below wing roots.
Ling/Temco/Vought A-7 Single seat attack and close support aircraft.
Corsair II Looks much like a snub nose F-8 Crusader.
A, B versions are Navy carrier-based attack
planes powered by P&W TF-30 turbofans and
armed with two 20 cannon. D is Air Force land-
based version with one Allison TF-41 turbofan
and armed with one 20-mm rotary cannon.
McDonnell-Douglas AV-8 Single-seat V/STOL close support and tactical
Harrier reconnaissance aircraft. License-built
British Aerospace Harrier.
Northrop A-9 Twin-engine, single-seat close air support
aircraft. Two Lycoming YF102 turbofans under
the wing roots of a high wing. Lost out to
Fairchild Republic A-10 for production orders.
Fairchild Republic A-10 Twin-engine, single-seat close air support
Thunderbolt II aircraft. Two General Electric TF34 turbofans
in pods above and behind low-mounted wings.
Primary armament is seven-barrel GAU-8/A
30-mm antitank cannon.
A-11 This one appears never to have been assigned.
The reasons are obscure. One possibility is
that the A-11 designation was not used because
someone might "confuse" it with the "A-11"
designation which LBJ applied deceptively
to the supersecret Lockheed A-12 spyplane.
Another possibility is that A-11 is the
designation given to an as-yet-unannounced
"black" project. Noone seems to know for
sure. Anyone who knows isn't talking.
McDonnell Douglas/General Two-seat low-observable medium attack aircraft.
Dynamics A-12 Extensive use of composites. Designed as
Avenger II replacement for Grumman A-6. Large flying
wing. Typical A-6 weapons load internally.
Additional ordinance can be carried externally
when stealth is not important. Range and
speed supposedly exceed those of A-6. Project was cancelled
in early 1991 due to cost overruns and schedule
slippages.
From this point on, there are "gaps", since these later A- aircraft were attack planes that had been converted from other roles.
General Dynamics A-16 Proposed close air support version of F-16 Fighting Falcon fighter. Not built. McDonnell Douglas A-18 Designation given to attack version of F-18 Hornet twin-engined, single-seat carrier-based fighter. Initially, the F-18 and A-18 were envisaged as separate and distinct aircraft fulfilling different requirements. However, during the design phase the two aircraft evolved in such a manner that they differed from each other only in minor details, and the Navy decided to combine both planes under the joint designation F/A-18. Douglas A-26A Counter Invader Originally designated B-26K. Conversion of existing B-26 airframe to counter-insurgency role. While operating in Thailand, the aircraft were redesignated A-26A, since a treaty between that government and the USA forbidded the basing of "bombers" in Thailand. Phased out of service in 1969. Cessna A-37 Dragonfly Initially designated YAT-37D. Attack version of T-37 tandem, two-seat primary jet trainer.
Sources:
-
American Combat Planes, Third Enlarged Edition, Ray Wagner, Doubleday,
1982.
-
McDonnell Douglas Aircraft, Rene J. Francillon, Naval Institute
Press, 1988.
-
Curtiss Aircraft, 1907-1947, Peter Bowers, Naval Institute Press,
1979.
-
Lockheed Aircraft since 1913, Rene J. Francillon, Naval Institute
Press, 1987.
-
Boeing Aircraft since 1916, Peter M. Bowers, Naval Institute
Press, 1989.
- United States Military Aircraft Since 1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.
