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Saab 17#Survivors

{{Short description|Swedish dive bomber}}

{{Use dmy dates|date=September 2016}}

{{Use British English|date=August 2022}}

{{Infobox aircraft

|name=Saab 17

|image=SAAB B17-20 - Flickr - Ragnhild & Neil Crawford.jpg

|type=Reconnaissance-dive bomber

|national_origin=Sweden

|manufacturer=SAAB

|designer =

|first_flight=18 May 1940

|introduction=March 1942Annerfalk, 1999, p.58

|retired=1968 (Ethiopia)

|primary_user=Swedish Air Force

|more_users=Imperial Ethiopian Air Force
Royal Danish Air Force

|produced=1941–1944

|number_built=326 (including 2 prototypes)

}}

The Saab 17 is a Swedish single-engine monoplane reconnaissance dive-bomber aircraft of the 1940s originally developed by ASJA prior to its merger into Saab. It was the first all-metal stressed skin aircraft developed in Sweden.

Design and development

File:Assembly-Halls-with-B17-planes-in-Trollhättan-142370502302.jpg assembly hall in 1944]]

The project was initiated in response to a 1938 request from the Flygvapnet (Swedish Air Force) for a reconnaissance aircraft to replace the obsolete Fokker S 6 (C.Ve) sesquiplane. Design work began at the end of the 1930s as the L 10 by ASJA, but once accepted by the Flygvapnet it was assigned the designations B 17 and S 17 for the bomber and reconnaissance versions respectively, and it became better known as the Saab 17.

The design chosen was a conventional mid-wing cantilever monoplane with a long greenhouse canopy and a single radial engine in the nose. Control surfaces were covered in fabric but the remainder was stressed-skin duraluminum. It could be fitted with wheels or skiis, both of which retracted straight to the rear along the underside of the wing, leaving prominent fairings, and when fitted with wheels the undercarriage doors could be used as dive brakes.Karlström, 1988, p.52 A retractable tailwheel was provided. A floatplane version was built in small numbers for coastal reconnaissance to replace the obsolete Svenska Aero S 5, with massive fairings joining the floats to the wings where the wheels would have been. To maintain stability small vertical fins were added to the horizontal stabilizer. The wings were reinforced so that it could be used as a dive bomber. Bomb racks were provided under the wings, along with a small bomb bay below the cockpit, although some examples used a conventional rack on the centreline. On the bomber versions, a crutch was fitted to swing the bomb clear of the aircraft in vertical diving attacks, when the bomb could otherwise have passed through the propeller. The reconnaissance versions lacked the crutch. Split flaps broken into four segments were fitted to the underside trailing edge of the wing.

Two L 10 prototypes were ordered, the first being powered by a {{cvt|880|hp}} Bristol Mercury XII radial engine built by Nohab in Sweden, and the second with an imported {{cvt|1065|hp}} Pratt & Whitney R-1830 Twin Wasp C radial.

Supplies of suitable engines remained a major problem, and resulted in the aircraft being built in three versions with different engines.

The definitive B 17A used the Swedish-built STWC-3 (Swedish Twin Wasp C-3), an unlicenced copy of the R-1830. The B 17B used a Bristol Mercury XXIV built by Svenska Flygmotor AB (SFA) in Sweden, and the B 17C used an imported {{cvt|1060|hp}} Piaggio P.XI radial from Italy.{{cite web|title= B 17 – Saab 17 (1941–1955) |url= http://www.avrosys.nu/aircraft/Bomb/157-b17/157B17.htm |website= Avrosys |access-date= 3 September 2015|pages= 1–5}} The United States government denied a request to purchase a licence to build the Twin Wasp, so an unlicensed, reverse engineered copy was built instead as the STWC-3 (Swedish Twin Wasp C-3) to supplement and replace the lower powered Mercury radials already being built under licence.Annerfalk, 1999, p.84 Until production caught up with demand, the earliest aircraft being delivered were flown to their destinations, the engines were removed and shipped back, to be used on the next aircraft to be delivered.{{cn|date=December 2020}}

Operational history

File:Saab B 17B on ground.jpg

File:Saab B17B in the air.jpg

The first flight was on 18 May 1940 and first deliveries of dive bombers to the Flygvapnet began in March 1942, while deliveries of reconnaissance versions began in June 1942, and the type was operational by September 1942 when the first exercises were carried out. Problems immediately arose with wing failures, and additional modifications were needed before it could be cleared for dive bombing, which remained limited to shallow attacks thereafter. The final aircraft was delivered on 31 August 1944.{{cite magazine|title=Fpl 17 – Saabs första konstruktion|magazine=Svensk Flyghistorisk Tidskrift |publisher=Svensk Flyghistorisk Tidskrift (Swedish Aviation History Journal)|date=June 2020|language=sv|page=8|issn=1100-9837}}

A B 17 was used to test the ejection seat Saab had developed for use in the Saab 21 pusher fighter, which was first successfully fired on 27 February 1944 with a dummy.Annerfalk, 1999, p.95

Stig Wennerström gained some fame in Sweden for successfully bailing out from a B 17 from low altitude, with his gunner, but would later become a spy for the Soviet Union.Annerfalk, 1999, p.144

For several months in late 1944 and early 1945 fifteen B 17As were operated by the Danish Brigade in Sweden (Danforce) a unit of 5000 men (including 50 airmen) in Sweden which had been formed to assist in liberating occupied Denmark from the Nazis, and preventing the retreating German soldiers from using civilians as human shields, and carrying out scorched earth tactics as they had done elsewhere. However, due to the German surrender on 7 May 1945, the aircraft were no longer needed and were returned to Flygvapnet control a couple of months later.Annerfalk, 1999, p.100

Rapid advances in aviation related to improved aerodynamics, higher engine power and finally the introduction of jet engines, resulted in it having a short career, and it was gradually withdrawn from frontline service between 1948 and 1950, while the last examples were retired from secondary roles by 1954. Over the next few years, examples would be sold off to various operators.

Due to the efforts of Carl Gustaf von Rosen, the Ethiopian Air Force bought 47 which were operated from 1947 until 1968.

From 1951, 19 B 17s were loaned to Svensk Flygtjanst AB and AVIA for use as target tugs and painted yellow with civilian markings. One of these, a B 17A SE-BYF was sold to the Austrian Österreichische Luftstreitkräfte in 1957, where it continued to be used as a target tug until retired in 1963. Two B 17As were also sold to the Finnish Ilmavoimat in 1959 and 1960, also as target tugs. Neither of the Finnish aircraft lasted long before being destroyed in accidents.{{cite magazine|title=Saab 17 i flygvapnet, Spaningsplan och dykbombflygplan – S17, B17 |magazine=Svensk Flyghistorisk Tidskrift |publisher=Svensk Flyghistorisk Tidskrift (Swedish Aviation History Journal)|date=June 2020|language=sv|issn=1100-9837|page=14}}

Variants

=Company designations=

;L 10

:internal ASJA/Saab designation; two produced

File:Saab S 17BS.jpg

;L 10A

:internal ASJA/Saab designation for 17A, B, and C

;L 10BL

:internal ASJA/Saab designation for S17BL

;L 10BS

:internal ASJA/Saab designation for S17BS

=Flygvapnet designations=

;P 7

:L 10 development prototypes

;B 8

:Preliminary designation for bomber version of L 10, not used

File:Saab B 17C.png along with a prominent exhaust on the same side, and the 17C had two intakes on either side of the top]]

;B 17A

:Bomber with {{cvt|1065|hp}} Svenska Flygmotor Aktiebolaget (SFA)-built STWC-3 (Pratt & Whitney R-1830-S1C3G Twin Wasp) radial engine; 132 built

;B 17B

:Bomber with {{cvt|980|hp}} SFA-built Bristol Mercury XXIV radial engine; 55 built

;B 17C

:Bomber with {{cvt|1060|hp}} Piaggio P.XIbis R.C.40D radial engine; 77 built

;S 15

:Preliminary designation for reconnaissance version of the L 10, not used

;S 17BL

:Reconnaissance version of B 17B with wheeled or ski landing gear; 21 built

;S 17BS

:Reconnaissance version of B 17B with floats, powered by a Bristol Mercury XXIV engine; 38 built

A total of 326 Saab 17 aircraft of all types were produced, and some bombers were converted into reconnaissance aircraft.

Operators

File:17320 Danmarks Tekniske Museum.jpg in Danish markings]]

;{{AUT}}

;{{DEN}}

;{{flag|Ethiopia|1897}}

;{{FIN}}

;{{SWE}}

Surviving aircraft

File:Saab B17A Fv17239 1.jpg. A second B 17 is displayed in the museum.]]

Five Saab 17s are known to be in existence today, three of which are on public display.

The Swedish Air Force Museum in Linköping has two aircraft in their collection, a S 17BL '5', serial 17005 which is on static display in the museum, and a B 17A '7', serial 17239, the latter being kept in airworthy condition and which is periodically flown.{{cite web|last=Poelstra|first=Jack|url=http://avia-dejavu.net/photo%20SE-BYH.htm|title=SE-BYH Saab B 17A c/n 17239 - Swedish Air Force Museum - Groningen Airport Eelde in Holland - 7 July 2005|access-date=27 December 2020}}

Another B 17A 'E', serial 17320 which was donated by the Flygvapnet after having served as a target tug is on display at the Danish Museum of Science and Technology in Helsingør/Elsinore.

Two former Ethiopian B 17As were recovered in the 1990s and purchased by a South African collector as a part of a large batch of ex-Ethiopian aircraft. These were shipped to Lithuania but their current status and location is unknown following the collapse of the collector's business interests.{{cite web|title=Baltbound Bombers – 2|url=http://lae.blogg.se/2013/february/baltbound-bombers-2.html|website=Lae – inte bara en stad på Nya Guinea|access-date=3 September 2015|language=sv}}

Specifications (B 17C)

{{Aircraft specs

|ref=Saab Aircraft since 1937Andersson, 1989, pages 59–65

|prime units?=met

|crew= Two

|capacity=

|length m=10

|span m=13.7

|height m=4.5

|wing area sqm=28.5

|airfoil=

|empty weight kg=2680

|gross weight kg=3870

|eng1 number=1

|eng1 name=Piaggio P.XIbis R.C.40D

|eng1 type=14 cylinder air-cooled radial piston engine

|eng1 hp=1060

|prop blade number=3

|prop name=Piaggio P.1001 variable pitch propeller

|prop dia m=

|max speed kmh=435

|cruise speed kmh=370

|minimum control speed kmh=125

|range km=1700

|ceiling m=9800

|climb rate ms=10

|wing loading kg/m2=139

|power/mass={{cvt|0.220|kW/kg}}

|guns=

|bombs=

  • {{cvt|700|kg}} of bombs could be carried. Racks were provided under the wings, in an internal bomb bay and externally on the fuselage centreline.

}}

See also

{{Aircontent

|related=

|similar aircraft=

|lists=

|see also=

}}

References

{{Commons category}}

=Citations=

{{reflist}}

=Bibliography=

  • {{cite book|last=Annerfalk|first=Anders|title=Flygvapnet An Illustrated History of the Swedish Air Force|publisher=Aviatic Förlag|location=Ljungsbro, Sweden|year=1999|isbn=91-86642-049}}
  • {{cite book |last=Andersson|date=1989 |first=Hans G. |title=Saab Aircraft since 1937 |publisher=Smithsonian Institution Press / Putnam|location=Washington, D.C. / London, UK|isbn=0874743141|pages=59–65}}
  • {{cite book|last=Karlström|first=Björn|title=Flygplans - Ritningar 3 Svenska Flygvapnets Bombflygplan 1926-1986|publisher=Allt om Hobby|location=Stockholm|year=1988|isbn=9789185496259}}

=Further reading=

  • {{cite book|editor=Bill Gunston|title=Jane's Fighting Aircraft of World War II |year=1989|edition=2001 |publisher=Military Press & Crescent Books |location=New York & London |isbn=1851704930}}
  • {{cite book|last1=Widfeldt|first1=Bo|last2=Hall|first2=Åke |title=SAAB 17; Den Forsta Egna Konstruktionen|publisher=Air Historic Research|year=1997|isbn=9789197160582|language=sv}}
  • {{cite magazine|last1=Edlund|first1=Ulf|last2=Andersson|first2=Lennart|last3=Berns|first3=Lennart|last4=Stridsberg|first4=Sven|title=Svensk flyghistoria under 1900-talet|magazine=Svensk Flyghistorisk Tidskrift |location=Stockholm|publisher=Svensk Flyghistorisk Förening|year=2003|issn=1100-9837}}

{{Saab aircraft}}

{{ASJA aircraft}}

{{Swedish military aircraft designations}}

17

Category:1940s Swedish bomber aircraft

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Category:Mid-wing aircraft

Category:Aircraft first flown in 1940

Category:Aircraft with retractable conventional landing gear

Category:Single-engined piston aircraft