RYAN SPORT TRAINER ST-1 STM ST-3
ST-4 USAAC NETHERLANDS AUSTRALIA PT-20 PT-21 PT-22 NR-1 YPT-25
SOFTBOUND BOOK BY DORR B. CARPENTER (82 PAGES)
--------------------------------------------------------------------------------------------------------
Additional Information from Internet Encyclopedia
The Ryan STs were a series of two seat, low-wing
monoplane aircraft built by the Ryan Aeronautical Company. They were used as
sport aircraft, as well as trainers by flying schools and the military of
several countries.
T. Claude Ryan was the founder of the Ryan Aeronautical
Company, the second incarnation of a company with this name, and the fourth
company with which he had been involved to bear his name (the first, Ryan
Airlines, was the manufacturer of the Ryan NYP, more famously known as the
Spirit of St. Louis). He began the development of the ST (for "Sport
Trainer", and also known as S-T), the first design of the company, in
1933.
The ST featured two open cockpits in tandem in a metal
semi-monocoque fuselage of two main frames - one steel, the other half of steel
and half of aluminium alloy (alclad) - to take the loads from the wing spars
and six more alclad frames; and alclad skin. It had wings in three sections of hybrid
construction; the center section integral with the fuselage had tubular steel
spars, the front spar a simple tube with an external brace to the upper
fuselage, and the rear spar in the form of a parallel chord truss. The two
outer wing panels had wooden spars and alclad ribs, with diagonal rods bracing
the wings internally. Alclad sheet was used to form the leading edges, and
fabric covered the whole structure. When attached, the outer wings were braced
with flying wires to the fixed conventional landing gear and landing wires to
the upper fuselage.
Five STs were built before the follow-on ST-A (A for
Aerobatic) was developed with a more powerful engine. A single ST-B was
produced, this being an ST-A with only one seat and an extra fuel tank where
the front cockpit normally was; this aircraft was subsequently converted back
to ST-A standard. The ST-A was further
developed as the ST-A Special, with an engine of increased power.
In 1937 the ST-A Special was developed into a military
version, the STM (also ST-M) series. Changes included wider cockpits to enable
military pilots to enter and exit while wearing parachutes, and provision for a
machine gun on some examples. Variants in the series included the STM-2P
single-seat version armed with a machine gun delivered to Nationalist China;
and the STM-S2, which could be fitted with landing gear or with EDO Model 1965
floats.
After the ST-M came the ST-3, a substantial redesign in
1941 partly brought about by the unreliability of the Menasco engines fitted to
STs to that point. The United States Army Air Corps (USAAC) had purchased
several dozen ST-M variants under various designations and had Ryan
Aeronautical re-engine most with Kinner R-440 radial engines. The USAAC found
the modification to be beneficial and asked Ryan Aeronautical to design a
variant with this engine as standard, and with airframe modifications
considered desirable from in-service experience. The ST-3 that resulted
featured a longer and more circular wider fuselage, this being suggested by the
circular radial engine. Other changes included a revised rudder, balanced
ailerons and elevators, and strengthened main landing gear with the legs spaced
further apart. The streamlining spats covering the mainwheels, found on ST
series aircraft to that point, were deleted as well. The ST-3 served as the
basis for military versions ordered by the USAAC and the United States Navy
(USN).
The ST-3 gave rise to another model developed in 1941 and
early 1942, this was the ST-3KR (for Kinner Radial). The ST-3KR had a more
powerful Kinner R-5 engine fitted and became the definitive model; more than
1,000 military versions were built during World War II as PT-22 Recruits. The
final variant was the ST-4, which was a version of the ST-3 with a wooden
fuselage, developed in case a shortage of "strategic materials" (i.e.
of metal) developed. Such a shortage did not eventuate and the ST-4 was not put
into mass-production.
Some U.S. Navy versions of the ST-3, the NR-1, were
converted to specialized ground trainers to teach cadets how to taxi aircraft
when on the ground or after landing, and especially in crosswinds. The main
wing was clipped back to the landing gear; a small nose wheel added to prevent
ground loops; a roll cage between cockpits to protect the pilot and cadet; and
the throttle modified so the engine could not go over a certain RPM.
The first Ryan ST flew for the first time on 8 June 1934 and
production began the following year, when nine aircraft were delivered. Except
for 1937 (when 46 aircraft were built), production rates remained low for
several years, at about one aircraft every two weeks. This changed in 1940 when
deliveries to military forces began in earnest; production that year was just under
three aircraft per week. Total production of civil and military aircraft prior
to the entry of the United States into World War II amounted to 315. Another
1,253 military versions were produced in 1942 and 1943, for a total of 1,568
aircraft of all models.
Most civil aircraft in the ST series were delivered in
the United States, although a few were exported to South Africa, Australia and
various countries in Latin America. An example of the ST-A was procured by the
USAAC in 1939 for evaluation as the XPT-16. This was followed by 15 YPT-16s,
the first time the USAAC had ordered a monoplane trainer. These were the first
of more than 1,000 Ryan STs to serve the USAAC, its successor, the United
States Army Air Forces (USAAF) and the USN.
A large number of STMs were exported in the 1930s and
early 1940s (prior to the entry of the United States into World War II) to
various Air forces, with the biggest customer being the military of the
Netherlands East Indies (NEI, now Indonesia). The NEI Army and Navy took
delivery of 84 STM-2s and 24 STM-S2s in 1940 and early 1941. Another 50 STM-2Es
and STM-2Ps were exported to Nationalist China, while others were exported to
Bolivia, Ecuador, Guatemala, Honduras, Mexico and Nicaragua.
After the Japanese invasion of the NEI many Ryans in that
country were pressed into combat, especially in reconnaissance roles, and large
numbers were shot down or destroyed on the ground. Surviving STM-2s and STM-S2s that were not
captured by the Japanese were shipped to Australia, where 34 entered service in
the Royal Australian Air Force as trainers. Many of those that survived until
the end of World War II were then placed on the civil register in Australia and
elsewhere, and some are still flying almost 70 years after they were built.
ST Prototype and first model, fitted with a Menasco B4
engine of 95 hp; five built.
ST-A Improved ST designed for aerobatics, fitted with a
Menasco C4 engine of 125 hp;[17] 73 built.
ST-A Special Improved ST-A, fitted with a Menasco C4S
engine of 150 hp;[18] 10 built.
ST-B Single-seat variant of ST-A with extra fuel tank in
place of front cockpit; one built, later converted to ST-A.
STM Military version of ST-A Special with wider cockpits,
some with provision for a machine gun; 22 built.
STM-2 Variant of STM for Netherlands East Indies Army and
Navy; 95 built.
STM-2E Variant of STM delivered to China, fitted with a
Menasco C4S2 engine of 165 hp; 48 built.
STM-2P Single-seat variant of the STM-2E with provision
for a machine gun, also delivered to China; 2 built.
STM-S2 Variant of STM-2 with interchangeable wheel landing
gear or floats for Netherlands East Indies Navy; 13 built.
ST-W Experimental conversions, with a Warner Scarab
radial engine; one converted from USAAC YPT-16 with Scarab of 125 hp; one
converted from USAAC PT-20A with Super Scarab of 160 hp.
ST-3 Variant with new fuselage shape and a Kinner B-5
radial engine of 125 hp; one built.
ST-3KR Variant of ST-3 with a Kinner R-5 radial engine of
160 hp, one built.
ST-4 Variant of ST-3 manufactured with wooden fuselage;
one built.
US military designations
USAAC/USAAF
PT-16
XPT-16: A single ST-A bought by the USAAC for evaluation.
XPT-16A: XPT-16 re-engined with Kinner R-440 radial
engine of 125 hp.
YPT-16: A total of 15 aircraft similar to the ST-M
ordered for service trials.
PT-16A: 14 YPT-16s re-engined with Kinner R-440 engine.
PT-20 Production version of PT-16; 30 built.
PT-20A: Designation of PT-20s that were re-engined with
Kinner R-440 engines.
PT-21 Military production version of ST-3; 100 built.
PT-22 Recruit: Military production version of ST-3KR with
Kinner R-540-1 engine; 1,048 built, including PT-22As.
PT-22A: Designation for 25 examples of ST-3KR built for
the Royal Netherlands Air Force but not delivered, aircraft subsequently taken
by the USAAF.
PT-22C: Aircraft re-engined with Kinner R-540-3 engines,
250 aircraft modified.[1][20]
YPT-25 Military version of ST-4, ordered for evaluation;
five built.
USN
NR-1 Naval production version of ST-3; 100 built