DETLEF BILLIG COLLECTION
No. 10880. North American NA-16-4M Sk 14 (610) Swedish Air Force
Photographed at Flygvapenmuseum, Linköping, Sweden, July 27, 2008, by Detlef Billig

North American NA-16-4M Sk 14

10/31/2011. The last prototype built in the General Aviation plant at Dundalk, Maryland, emerged as the NA-16, a basic trainer to USAAC requirements and sire of an enormous family of related designs which placed North American firmly on the map. Over 17,000 examples of the various derivatives of the
NA-16 were built in North American's Los Angeles and Dallas plants in the next ten years or so, and over 4,500 more were built under license in four other countries.

As the AT-6 Texan or Harvard, a derivative of the basic NA-16 was used as an advanced pilot trainer in America, Britain and several other Allied countries throughout the war, and subsequently became almost as widely known and used throughout the world as the Douglas C-47 Dakota. The NA-16 as first flown was an all-metal (with partial fabric covering) low-wing monoplane with open cockpits in tandem, a fixed, unfaired undercarriage and a cowled 400 hp Wright R-975 Whirlwind radial engine. With the civil registration X-2080, it first flew at Dundalk in April 1935 and was submitted in the USAAC contest for evaluation at Wright Field in the same month.

The design was selected for production as a basic trainer, although the USAAC requested several modifications including an enclosure over the cockpits. The prototype was modified, as NA-18, to have this feature plus faired undercarriage legs and a 600 hp Pratt & Whitney R-1340 engine, in which guise it was eventually sold to Argentina. Other modifications introduced on various later models included a retractable undercarriage, changes in the wing tip and tail unit shape, changes in engine installation and introduction of armament.

In all, 63 different NA charge numbers were applied to members of the NA-16 family, including those built for the USAAC/USAAF/USAF, US Navy and for export. Most of these variants were intended primarily as trainers, but they also included single-seat fighters and two-seat light bombers. Many of the trainer variants also carried, or had provision for, guns and bombs.

The export of NA-16 variants represented a significant part of North American's business between 1935 and 1939. Although many of the export aircraft carried NA-16 designations, they were also covered by separate charge numbers. The NA-31 charge number covered a single NA-16-4M (c/n 31-386) basic trainer for Sweden, similar to the BT-9 with a 450hp Wright
R-975-E3 engine. Built at Inglewood, it was sold to AB Svenska Järnvägsverkstädernas Aeroplanavdelning (ASJA, Swedish Railway Workshops Aircraft Department) together with a manufacturing license.

ASJA delivered the sole NA-31 to the Swedish AF and it was designated
Sk 14 and received the s/n 671. The Sk 14 was Swedish first trainer with enclosed cockpit. It was entirely built of metal, while the fuselage and the control surfaces were covered in fabric, and it was fitted with a fixed tailwheel landing gear.

In 1938, the Swedish AF signed a contract with ASJA for the delivery of 35 aircraft. Under the batch number NA-38, a second NA-16-4M (c/n 38-540) was bought unassembled from North American to be used as a pattern aircraft and allotted s/n 609 it was delivered to the Swedish AF as the last aircraft in the first batch. The remaining 34 Sk 14s were allotted the s/n 672 to 699 and 603 to 608, and those were delivered to the Air Force Flight Academy (F 5) at Ljungbyhed between 1939 and 1940. A second batch of 18 aircraft was ordered by the Swedish AF at the end of 1939, these aircraft were delivered in the first half of 1941 with s/n 5810 to 5827.

ASJA merged into SAAB in 1939, and the third batch of 23 aircraft (s/n 5824 to 5850) ordered was produced by the SAAB factory at Linköping. As delivery of the Wright engines suffered an American embargo, these 23 aircraft were instead equipped with the Italian 500 hp Piaggio P VIIRC16 engine, and designated Sk 14A; deliveries took place in the first half of 1942. A fourth batch of 60 Sk 14As (s/n 14001 to 14060) were ordered in 1942, these aircraft were built at the SAAB plant at Trollhättan, and were delivered between 1943 and 1946. Some aircraft, designated Sk 14N (site files), were later fitted with a nosewheel landing gear to familiarize pilots with the tri-gear of the J 21A.

The pictured aircraft is a hybrid as it has been rebuilt to authentic Sk 14 status using parts of the ex-RAAF CAC Wirraway (s/n A20-223) and an ex-RCAF North American NA-64 Yale.

Created October 31, 2011