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Stinson SM-2 / SM-7 / SM-8 / Junior
 
Stinson-Junior-01
 
Stinson Aircraft had introduced their large high-winged six-seat SM-1 Detroiter in 1927. The SM-1 was sold successfully to airlines and other commercial operators, but it was too large to appeal to private owners.
 
 
Stinson-Junior-02
 1928 Stinson SM-2 Junior
 
Stinson introduced its revo­lutionary Detroiter in February 1926. The first ever enclosed passenger aircraft used by an airline (Northwest on 5 July 1927), and designed by Eddie Stinson. The Detroiter was named after the group of Detroit motor moguls who financed their building.
 
The Jr-S has solid spruce plank wing spars, routed to I‑section, and a total of 36 wooden ribs. The wing also con­tains mild carbon steel drag tubes and steel drag wires. The ailerons span 9ft 8in and have a chord of 15.75in. They have steel frames, a 4130 tubular spar and nine metal ribs. The wing is braced by gin‑chord lift struts. The struts have a streamlined shape formed with a 4130 steel tube and 11 mild steel stamped ribs in the for­ward struts, and 14 in the rear struts.
 
 detroiter-jr-s
Jr-S

 

The fuselage is a conventional welded chromoly structure and has a nicely‑upholstered cabin which is 8ft 3in long from the instrument panel to the rear bulkhead, and 40in wide across the front and rear seats. The height at the forward seats is 48in, and 46in at the rear. A 69 lb capacity baggage area is located aft of the rear seats. Dual con­trol wheels are fitted, and the instrument panel layout is close to the original, although it now contains mostly modern instru­ments.
 
The tail surfaces have 4130 tubular steel frames with tubu­lar ribs, and the tailplane spans 13ft. The 31.5in‑high fin, which has a maximum chord of 34in, has two ribs. The rudder is 67in high, and has a 28in maximum chord and seven ribs. The tailplane's maximum chord is 31in, the elevator's 23.25in, and each has ten ribs. Ailerons and rudder are cable controlled, and push‑pull tubes are used in the elevator. The tailplane can be adjusted by a centrally posi­tioned lever in the cabin which activates push‑pull tubes connected to a crank in the aft end of the fuselage.
The strut‑braced main land­ing gear is made from chromoly tubes and employs a Stinson ­designed oleo and spring hydraulic strut with 7in travel. The main tubular vees are streamlined with pine fairings and covered with Ceconite. Original Autofan wheels, with mechanical brakes, carry McCreary 8.50 x 10in tyres. Track is 9ft 6in. The tailwheel is again an Autofan, with a 5.00 x 4in tyre, and its wheel is installed on a fully castoring oleo strut. A small brake is attached to the outer cylinder to prevent shimmy.
 
The Jr‑S has a span of 41ft l in and a chord of 6ft 3in. Its over­ all length is 26ft 1lin, and height 8ft 9in. It weighs 2,300 lb empty and 3,265 lb fully loaded. Its original fuel capacity was 60 US gal. The Jr‑S's performance was similar to that of many other four‑seaters of the early 1930s, but the type saw heavy service with small airlines, charter operators, and private owners.
 
The take‑off run is 570 to 600ft at 50 mph with two aboard, or 1,000ft with four passengers. It climbs at 600ft/min at 65 mph with two, and cruises at 90 mph at 1,850 rpm (engine redline is 2,200 rpm). At cruis­ing speed its fuel consumption is 13‑14 US gal/hr, permit­ting a 5hr range with reserves.
 
In 1931 a Stinson Jr‑S was factory priced at $5,775.

 

Stinson therefore redesigned the aircraft with shorter span wings, shorter fuselage and a choice of less powerful engines as the SM-2 Junior. The aircraft was a strut-braced high-wing monoplane with a sturdy outrigger undercarriage which was braced against the wing support struts and the initial 110 h.p. Warner Scarab engine was normally left uncowled. The first SM-2 flew in mid-1928 and deliveries commenced that year. Later versions of the SM-2 had higher-powered engines of between 165 h.p. and 225 h.p.
 
 
The first of the Stinson “Junior” line, the SM-2, rolled off the Northville, Michigan factory floor in 1928. The airplane fuselage was welded chrome-moly steel tubing construction attached to a wooden wing structure with an overall fabric cover. Although designed to be used extensively for private use, with successive power increases, the aircraft became too big and heavy for the light plane class. They were put into service as air taxis and flight demonstrators. One of the early SM-2 models participated in the 1928 National Air Tour. Piloted by Randolph Page, the plane placed third in the tour. Later models of the Junior series would see many engine and dimensional changes.
 
 
Stinson-Junior-03
 1932 Stinson SM-8A Junior N408Y
 
The design was further developed to produce the more powerful and heavier SM-7 and SM-8 models which were full four-seaters and these were also used by commercial firms. The Junior R of 1932 had a deeper fuselage and a low-set stub wing to mount the undercarriage and wing struts.
 
The SM-8A, A.T. C. #295, equipped with a Lycoming R-680 9-cyclinder radial engine was introduced in April of 1930. The price was $5775. The low price tag paid off and by the end of 1930 there were more SM-8As sold then all other cabin airplanes put together. The airplane could cruise comfortably at 105 mph with a ceiling of 14,000 feet and a range of about 500 miles.
 
Stins-Jun-ad
 
 A total of 321 Stinson Juniors were built between 1928 and 1933, of which 27 survived in 2001 and several of these were airworthy in private hands.
 
 
 1929 Stinson SM-8A Junior

 

 
 
Variants:
 
SM-2 
Engine: Warner Scarab 110 h.p.
 
SM-2AA 
Engine: Wright J6-5 165 h.p.
 
SM-2AB 
Engine: Wright J5 220 h.p.
 
SM-2AC 
Engine: Wright J6-7 225 h.p.
Length: 29 ft 0 in
Wingspan: 41 ft 8 in
Height: 8 ft 3 in
Wing area: 236 ft2
Empty weight: 2,169 lb
Gross weight: 3,229 lb
Maximum speed: 135 mph
Cruise speed: 113 mph
Range: 450 miles
Service ceiling: 22,000 ft
Rate of climb: 1,200 ft/min
Crew: 1
Capacity: 3 passengers
 
SM-2ACS
floatplane version of the SM-2AC
Engine: Wright J6-7 225 h.p.
Length: 29 ft 0 in
Wingspan: 41 ft 8 in
Height: 8 ft 3 in
Wing area: 236 ft2
Crew: 1
Capacity: 3 passengers
 
SM-7A 
Engine: Wright J6-9 300 h.p.
 
SM-7B 
Engine: Wasp Junior 300 h.p.
 
SM-8A 
Engine: Lycoming R-680 215 h.p.
Wing Span: 41 ft. 6 in
Wing Area: 234 sq. ft
Airfoil: Clark Y
Length: 28 ft. 11 in
Height: 8 ft. 9 in
Empty Weight: 2061 lb
Gross Weight: 3195 lb
Useful Load: 1134 lb
Cruising Speed: 105 mph
Maximum Speed: 125 mph
Ceiling: 14,000 ft
Cruising Range: 500 mi
Price April 1930: $5775 at factory
 
SM-8B 
Engine: Wright J6-7 225 h.p.
 
SM-8D 
Engine: Packard DR-980 diesel 225 h.p.
 
Junior R 
deeper fuselage.
28 Units built
Engine: Lycoming R-680 215 h.p.
 
Junior R-2 
Engine: Lycomong R-680-BA 240 h.p. 3 Built.
 
Junior R-3 
as R-2 with retractable undercarriage 3 built.
Engine: Lycomong R-680-BA 240 h.p.
 
Junior R-3-S 
Engine: Lycoming R-680-6 245 h.p.
 
Jr‑S De­troiter
Engine: Lycoming R‑680 radial, 215 hp
Cruise: 85 mph
Seats: 4.
 
 
Junior W 
generally similar to the SM-7B
Engine: Wasp Junior
 
 
 
 
 
 
 


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