Stinson L-5

Stinson L-5
Type:	Liaison aircraft, search and rescue , artillery observation and reconnaissance
Design country:	United States
Manufacturer:	Stinson Aircraft Corporation
First flight:	June 28, 1941
Production time:	October 1942 - November 1945
Number of pieces:	3590 (3896)

The Stinson L-5 "Sentinel" (factory name Vultee Model 76) was a light liaison and reconnaissance aircraft for the US armed forces, which was derived from the Stinson 105 light aircraft developed by the Stinson Aircraft Corporation in the late 1930s . From November 1939 Stinson was part of Vultee Aircraft Inc., so that the model number 76 joins the Vultee sequence.

The L-5 was one of the most important American aircraft of World War II, although outnumbered and in popularity by the Piper L-4 . Nearly 3,600 were made in Wayne, Michigan between 1942 and 1945, with a few hundred still in existence today. As a true workhorse of the US Army Air Forces, the L-5 completed a variety of different missions, such as the transport of officers between the bases (liaison aircraft), search and rescue services , photo reconnaissance , courier service, supply missions and artillery observation. The short take-off and landing distance made it possible to use it under simple conditions outside of paved runways. The aircraft and its crews were given appreciative nicknames such as “Flying Jeep” (German: “Fliegender Jeep”) or “Jungle Angel” (German: “Jungle Angel”) by the ground troops.

history

prehistory

In March 1940, the USAAC held a comparison flight at Wright Field , in which an inexpensive successor to the expensive to produce Stinson L-1 (Vultee Model 74) was to be found. Stinson participated with a modified Model 10 (HW-80) of the Stinson 105, which had received a plexiglass roof. The assessment was good, but the rolling properties in difficult ground conditions were assessed as unsatisfactory, just like with the other six competitors. As a consequence of the test results, A. P. Fontaine, who had also designed the L-1, constructed the Model 75B (in the Vultee naming sequence) with two seats in tandem and a 100 HP Lycoming O-235 . The first flight of the machine ( registration number NX27711), which can be regarded as the first prototype of the Stinson L-5, was on June 19, 1940. In August the engine was replaced by a Franklin 6AC-264-F2 with 120 hp. The Model 75B, which was only built once, was the forefather of the L-5, which became known as the Flying Jeep during World War II .

development

Fontaine developed the Model 75B further to the Model 76, which had a larger body and a higher weight. However, it kept the original wooden wing of the Stinson 105. The cabin received enlarged glazing, which now also included the rear area, with the side windows sloping outwards to improve visibility. In contrast to the Model 10 of the Stinson 105, which only had a tank in the right wing root, a second tank was also installed on the left.

The prototype of the Model 76 (NX27772), equipped with a 175 hp Lycoming engine, flew for the first time on June 28, 1941. A spin test that almost ended in a crash showed that the fixed slat, which spanned the entire span, caused an asymmetrical lift distribution and thus can lead to a no longer controllable flat spin. This was remedied by shortening the slat to half the span, as with the Model 10, and slightly larger tail surfaces. With the STOL properties achieved in this way, a take-off distance of 200 m was sufficient to fly over an obstacle 15 m high.

The breakthrough for the Army to order 275 aircraft came with the use of the 185 hp Lycoming O-435-1 , which was built into a prototype with enlarged vertical stabilizers and other improvements. By 1942, 1700 L-5 "Sentinels" were ordered by the army, and with additional funds from Congress a further 2400 by 1945. Improved versions such as the L-5B, L-5C, L-5E and the L-5G were created in the course of production .

Production ended in November 1945 after 3590 copies were delivered to the USAAF. Orders for 900 more machines had been canceled. In 1948, the NACA in Langley Field equipped an L-5E with a silencer and a five-blade propeller, whereby the speed was reduced to 1000 min ⁻¹ via a gearbox. Despite the reduction of the noise level from 99 to 66 decibels (which corresponds to a reduction of 90%), the conversion could not be used as a low-flying stealth aircraft due to the higher weight .

commitment

The L-5 was in service in all theaters of war during World War II. In addition to the USAAF and US Navy, the US Marines (USMC) also used the OY Sentinel in the Pacific War with the VMO-3, VMO-4 and VMO-5 observer squadrons, including from Jeep carriers such as the USS White Plains . In September 1943, an L-5 took part in tests with the Brodie system . The Marines also equipped individual machines with temporarily attached bazookas .

With the outbreak of the Korean War , the US forces returned the L-5 to its original role. The USAF decommissioned the L-5 in 1953, but four years later bought an L-5G (57-6278), which they fitted out as a tow plane for the Air Force Academy . This aircraft was renamed the U-19B in 1962 . The few L-5s still available in the US Army were given the new designation U-19A

The last USMC sentinels were OY-2 of VMO-6, which were stationed from August 1950 to April 1952 until the arrival of the Cessna L-19 "Bird Dog" in Korea.

Until 1957, the L-5 remained in service in the US, Japan and Europe armed forces. After that, many aircraft continued to be operated by civilian owners, including as a sail tug in clubs, for banner towing and surveying.

The Royal Air Force took over 40 L-5s as Sentinel I and 60 L-5B (Sentinel II), which were used in Burma at No. 194 Squ. were used. The USAAF loaned one machine (42-99129) to the Australian Air Force (RAAF) and another (42-99186) was interned in Switzerland, where it received the service registration number A-96.

Other operators and civil use

At least one copy was also used by the Indonesian Air Force . The air forces of Ethiopia , Greece , Japan , the Republic of Korea , Mexico , the Philippines , Thailand and Italy received larger numbers . The largest civilian user of the L-5 outside of the US is India, where over 200 copies were still registered in the late 1980s. In the US, L-5 in December 1945 was awarded type certification, after which the entire remaining inventory of aircraft and spare parts from the Sentinel Aircraft Inc. was acquired. The company may still have manufactured individual machines from spare parts. Several hundred military L-5s were adapted for civil use. In the US, around 150 L-5s were still airworthy in the late 1980s.

variants

All variants were given a USAAF serial number, which was only changed to serial numbers of the respective operator after they were sold to the US Navy, US Marine Corps and Royal Air Force.

O-62

185-PS-O-435-1, 12 V electrical system, 275 aircraft built and renamed the L-5 during production. 1538 more copies were built directly as L-5. The approximately five machines still in existence in 1962 were renamed U-19A .

L-5A

Variant with 24-volt electrical system, order was canceled

L-5B

with flap on the right-hand side behind the observer's seat for transporting a carrier or a load of 90 kg, the hull has greater depth, a device for attaching a float, 730 units built

L-5C

similar to L-5B with K-20 camera installed, 200 built

L-5D

L-5B converted to L-5C standard during service

L-5E

like L-5C, but with improved STOL capabilities due to ailerons inclined by 15 degrees, plus larger brakes, 750 built

XL-5F

a machine converted from L-5B, with a 24-volt electrical system and other radio equipment

L-5G

like XL-5F, with 190-PS-O-435-11, controllable pitch propeller, higher takeoff weight, 115 built, 785 canceled

OY-1

306 L-5 / B / E have been transferred to the US Navy and US Marine Corps with new bureau numbers . 152 other machines did not receive new service serial numbers.

OY-2

Renaming in December 1948 for all OY-1 with a 24-volt electrical system

production

Acceptance of the L-5 by the USAAF:

version	1942	1943	1944	1945	TOTAL
O-62 / L-5	10	956	847		1,813
L-5B		160		552	712
L-5C			200		200
L-5E			314	436	750
L-5G				115	115
total	10	1,116	1,361	1.103	3,590

Technical specifications

Three-sided view of the L-5

Parameter	L-5 data	OY-2 data
crew	1 pilot + 1 observer
length	7.32 m
span	10.37 m
height	2.41 m
Wing area	14.40 m 2
Empty mass	668 kg	726 kg
Takeoff mass	992 kg	1028 kg
Top speed	206 km / h	202 km / h
Marching speed	185 km / h
Service ceiling	4800 m	4760 m
Max. Rate of climb	975 ft / min	900 ft / min
Range	620 km	571 km
Engines	1 × Lycoming O-435 -A with 190 hp	1 × Lycoming O-435-11 with 190 hp

See also

• List of aircraft types

literature

• John Wegg: General Dynamics Aircraft and their Predecessors , Putnam Aeronautical, 1990, ISBN 0-85177-833-X , pp. 141-143

Web links

Commons : Stinson L-5 Sentinel  - collection of images, videos and audio files

• L-5 at "Warbird Alley"
• Stinson on aerofiles.com

Individual evidence

1. ↑ Frank B. Mormillo: Combat survivors reunited . In: Airplane Monthly January 2013, pp. 42–46
2. ^ Nick Stroud: Arrested development . In: Airplane Monthly November 2005, pp. 30–33
3. ^ ER Johnson: American Military Transport Aircraft , McFarland and Co., 2013, p. 433
4. ↑ Photos and history of the Swiss A-96 (accessed on January 15, 2017)
5. ↑ L-5 production list
6. ↑ Statistical Digest of the USAF 1946, p. 100 ff.