SPL WW2 USAAF NORTH AMERICAN P-51A MUSTANG A-36 APACHE INVADER ALLISON V-1710
DIVE BRAKES
SOFTBOUND BOOK in POLISH
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Additional
Information from Internet Encyclopedia
The North American A-36 Apache (listed in
some sources as "Invader",
but also called Mustang) was the
ground-attack/dive bomber version of the North American P-51 Mustang, from
which it could be distinguished by the presence of rectangular, slatted dive
brakes above and below the wings. A total of 500 A-36 dive bombers served in
North Africa, the Mediterranean, Italy and the China-Burma-India theater during
World War II before being withdrawn from operational use in 1944.
With the
introduction of the North American Mustang I with the RAF Army Co-operation
Squadrons in February 1942, the new fighter began combat missions as a
low-altitude reconnaissance and ground-support aircraft. Supplementing the
Curtiss P-40 Tomahawks already in service, Mustang Is were first supplied to
No. 26 Squadron RAF, then rapidly deployed to 10 additional squadrons by June 1942.
First used in combat over the Dieppe Raid on 19 August 1942, a Mustang of No.
414 (RCAF) Squadron downed one of the formidable Focke-Wulf Fw 190, the first
victory for a Mustang. Despite the limited high-altitude performance of the
Allison V-1710 engine, the RAF was enthusiastic about its new mount which
"performed magnificently
During the Mustang
I's successful combat initiation, North American's president Howard
"Dutch" Kindelberger pressed the newly redesignated U.S. Army Air
Forces (USAAF) for a fighter contract for the essentially similar P-51, 93 of
which had passed into the USAAF when the Lend-Lease contract with Britain ran
out of funds. The Mustang IA/P-51 used four 20 mm Hispano wing cannon in place
of the original four .30 in (7.62 mm) M1919 Browning machine guns and
two .50 in (12.7 mm) M2 Browning machine guns mounted in the wings
and two .50 in (12.7 mm) "chin" machine guns. No funds were
available for new fighter contracts in fiscal year 1942, but General Oliver P.
Echols and Fighter Project Officer Benjamin S. Kelsey wanted to ensure the P-51
remained in production.
Since
appropriations were available for an attack aircraft, Echols specified
modifications to the P-51 to turn it into a dive bomber. The contract for 500
A-36A aircraft fitted with bomb racks, dive brakes, and heavier-duty wing, was
signed by Kelsey on 16 April 1942, even before the first flight of the first
production P-51 in May 1942. With orders on the books, North American Aviation
(NAA) began modifying the P-51 to accept the bomb shackles which had already
been tested in a "long-range ferry" program RAF had stipulated.
Engineering studies totaling 40,000 hours and wind tunnel testing with a
⅛-scale model was completed in June 1942. Utilizing the basic P-51 airframe and
Allison engine, structural reinforcing "beefed up" several high
stress areas and "a set of hydraulically operated dive brakes were
installed in each main wing plane." Due to the slightly inboard placement
of the bomb racks and unique installation of four cast aluminum dive brakes, a
complete redesign of the P-51 wing was required.
The first A-36A (42-83663) was rolled out of the NAA
Inglewood plant in September 1942, rapidly going through flight testing with
the first flight in October, with deliveries commencing soon after of the first
production machines emerged. The A-36A continued the use of nose-mounted
.50 in (12.7 mm) machine guns along with wing armament of four
.50 in (12.7 mm) caliber machine guns (this was the heaviest armament
package of all the Allison-power Mustangs). The USAAF envisaged that the dive
bomber would operate mainly at altitudes below 12,000 ft (3,658 m)
and specified the use of a sea level-rated Allison V-1710-87, driving a
10 ft 9 in (3.28 m)-diameter three bladed Curtiss-Electric propeller
and delivering 1,325 hp (988 kW) at 3,000 ft (914 m). The
main air scoop inlet was redesigned to become a fixed unit with a larger
opening, replacing the earlier scoop which could be lowered into the airstream.
In addition the A-36 carburetor air intake was later fitted with a tropical air
filter to stop sand and grit being ingested into the engine.
The A-36A-1-NA
"Apache" (although Apache was the A-36A's official name, it was
rarely used) joined the 27th Fighter Bomber Group composed of four squadrons
based at Rasel Ma in French Morocco in April 1943 during the campaign in North
Africa. The 27th had a mixed component of Douglas A-20 Havocs and A-36As while
the second operational unit, the 86th Fighter Bomber Group (Dive) arrived in
March 1943 with the first pilots trained and qualified on the A-36A. On 6 June
1943, both of these A-36A units flew combat missions directed against the
island of Pantelleria. The island fell to Allied attack and became the home
base for the two A-36A groups during the invasion of Sicily. The A-36A proved
to be a potent weapon; it could be put into a vertical dive at 12,000 ft
(3,658 m)with deployed dive brakes, thus, limiting the dive speed to
390 mph (628 km/h)("A36A-1 Flight Manual requires deployment
before starting a dive"). Pilots soon recognized that extending the dive
brakes after "peel-off" led to some unequal extension of the brakes
due to varying hydraulic pressure, setting up an invariable slight roll which
impeded aiming. Proper technique soon cured this anomaly and, subsequently,
pilots achieved extremely consistent results. Depending on the target and
defenses, the bomb release took place between 2,000 ft and 4,000 ft
(610 and 1,219 m), followed by an immediate sharp "pull up."
Dive brakes in the
wings gave the A-36A greater stability in a dive; however, a myth has arisen
that they were useless due to malfunctions or because of the danger of
deploying them and that they should be wired closed. Capt. Charles E. Dills,
27th Fighter-Bomber Group, 522d Fighter Squadron, XIIth Air Force emphatically
stated in a postwar interview: "I flew the A-36 for 39 of my 94 missions,
from 11/43 to 3/44. They were never wired shut in Italy in combat. This 'wired
shut' story apparently came from the training group at Harding Field, Baton
Rouge, LA."
However, tactical
reconnaissance training with P-51 and A-36 aircraft had delivered some
disquieting accident rates. At one time, A-36 training had resulted in the type
having "the highest accident rate per hour's flying time" of any
USAAF aircraft. The most serious incident involved an A-36A shedding both wings
when its pilot tried to pull out from a 450 mph (724 km/h) dive.
Combat units flying the A-36A were ordered to restrict their approach to a 70�
"glide" attack and refrain from using dive brakes. This order was
generally ignored by experienced pilots but some units did wire dive brakes
shut until modifications were made to the hydraulic actuators. Nevertheless,
the A-36 was used with great success as a dive-bomber, acquiring a reputation
for precision, sturdiness and silence.
By late May 1943,
300 A-36As had been deployed to the Mediterranean Theater, with many of the
first batch sent to the 27th to re-build the group following losses as well as
completing the final transition to an all-A-36A unit. Both groups were actively
involved in air support during the Sicilian campaign, becoming especially adept
at "mopping" up enemy gun positions and other strong points as the
Allies advanced. During this operation, the 27th Group circulated a petition to
adopt the name "Invader" for their rugged little bomber, receiving
unofficial recognition of the more fitting name. Despite the name change, most
combat reports preferred the name "Mustang" for all of the variants.
The Germans gave it a flattering, if fearsome, accolade, calling the A-36As:
"screaming helldivers."
Besides dive
bombing, the A-36A racked up aerial victories, totaling 84 enemy aircraft
downed and creating an "ace", Lieutenant Michael T. Russo from the
27th Fighter Bomber Group (ultimately, the only ace using the Allison-engined
Mustang). As fighting intensified in all theaters where the A-36A operated, the
dive bomber began to suffer an alarming loss rate with 177 falling to enemy
action. The main reason for the attrition was the hazardous missions that
placed the A-36A "on the deck" facing murderous ground fire. German
defenses in southern Italy included placing cables across hill tops to snare
the attacking A-36As. Despite establishing a "reputation for reliability
and performance, "the one "Achilles' heel" of the A-36A (and the
entire Mustang series) remained its vulnerable cooling system leading to many
of the losses. By June 1944, A-36As in Europe were replaced by Curtiss P-40s
and Republic P-47 Thunderbolts
A-36As had also
served with the 311th Fighter Bomber Group in the China-Burma-India theater.
The 311th had arrived in Dinjan, India by late summer 1943 after being shipped
across the Pacific via Australia. Two squadrons were equipped with the A-36A
while the third flew P-51As. Tasked with reconnaissance, dive bombing, attack
and fighter missions, the A-36A was outclassed by its main opposition, the
Nakajima Ki-43 "Oscar." The light and highly agile Japanese fighter
could outmaneuver the A-36A at all altitudes but did have some weak points: it
was lightly armed and offered little protection for pilot or fuel tanks.
However, the A-36A fought at a significant disadvantage, having to carry out
long-range missions often at altitudes above the "Hump" that meant
its Allison engine was below peak performance. In a fighter escort mission over
Burma, three A-36As were lost without scoring a single victory. The A-36A CBI
missions continued throughout 1943�1944 with indifferent results. The A-36A remained
in service in small numbers throughout the remaining year of the war, some
being retained in the US as training aircraft.
"The type's
relatively brief service life should not camouflage the fact that it made a
major contribution to the Allied war effort" especially in the
Mediterranean and it amounted to the first USAAF combat use of a Mustang
variant. The effectiveness of the A-36 as a ground attack aircraft was
demonstrated on 5 June 1944. In a well planned attack on the large, well
defended rail depot and ammo dump at Orte, Italy, Lieutenant Ross C. Watson led
a flight of four A-36s through a heavy overcast on the approach to the target.
Watson's A-36s scored several hits under intense anti-aircraft fire while Lt.
Watson's aircraft was hit and damaged by ground fire. Under continuing heavy
ground fire. Lt. Watson pressed home his attack and destroyed the ammo dump
before making an emergency landing at an advanced Allied airfield.
The USAAF later
ordered 310 P-51As which were essentially A-36s without the dive-brakes and
nose mounted weapons, leaving an armament of four wing-mounted 0.50 in
(12.7 mm) Browning machine guns. An Allison V-1710-81 1,200 hp
(895 kW) was fitted and used the same radiator and air intake as the
A-36A. The P-51A was still fitted with bomb racks although it was not intended
to be used primarily as a fighter-bomber and the racks were mainly used to
carry drop tanks.
Designated
NA-99, the P-51A Mustang was ordered in numbers of 1,200 by the U.S. Army in
August 1942. No ground attack here, no dive brakes, just pure fighter. This was
the best fighter the U.S. had below 22,000 feet. This according to the AAF
School of Applied Tactics at Orlando, FL.
The
P-51A was powered by the Allison V-1710-81 which had automatic boost control
and rated at 1,200 horsepower. This Allison had increased performance at
altitude over the V-1710-39 used in the P-51. The propeller was a 3-blade, 10
feet 6 inch Curtiss electric. Top speed was 390 mph at 20,000 feet and the
service ceiling was 31,500 feet. There were two underwing mounts for bombs or
drop tanks. Gross weight increased to 10,600 lbs. max with an average load of
8,600 lbs.
Range was 750 miles at 300 mph on internal fuel. Add two 125 gallon drop tanks
and you go 2,000 miles at reduced power (not that anyone want to go that far
inside the P-51A, but you could if you needed to).
First flights were in February 1943 and deliveries began in March. The Mustang
was delivered to the AAF in olive drab on top and a grey on bottom.
Serials for the P-51 were 43-6003 to 43-6312 starting with the P-51A-1NA and
ending with the P-51A-10NA. 35 were used as recon F-6B and 50 were sent to the
RAF to replace the NA-91 models earlier held back.
The P-51A served mainly as a fighter and escort
in the China/Burma/India theatre (CBI). Modified versions called the F-6B, were
fitted with camera equipment for recon and served in the ETO. The P-51A would
see service into 1945, long after replacement models were in service.
Production would be cut far short of the 1,200 ordered. As soon as the Rolls
Royce Merlin modifications to the P-51 were deemed worthy, production was
shifted to the new models. In all, 310 P-51As were produced by NAA.