A.T.C. #335 (7-10-30) STINSON "AIR LINER", SM-6000

Fortified with liberal financing that came about through a merger with the huge Cord Corp., "Stinson" launched an ambitious program of aircraft manufacture for 1930-31 and utterly amazed those in the industry with its many bargain offerings. Of course Stinson's prices were geared to volume selling and it was not long before manufactured units reached a total large enough to justify the nearly ridiculous prices.
With a handful of different "Junior" models now available and older "Detroiter" models still on the available list, Stinson looked eagerly to the possibility of developing a relatively low cost trimotored airplane for use by the nation's air-lines. Careful studies dictated a certain course to take in the design of a cheaper trimotor and the SM-6000 "Air Liner", as shown and described here, was the end result. Introduced early in 1930 as a 10 place craft with 3 "Lycoming" engines for $23,900, the new "Air Liner" immediately classed itself as a bargain buy, with interested and unbelieving inquiries coming from all sides. After receiving certification later in 1930, Stinson announced a price reduction on the new SM-6000 to the ridiculously low figure of $18,000, mostly to entice the air-lines into buying, since several of them were known to be about ready for some new or larger equipment anyhow. This move had no immediate effect on any of the established carriers but it did prompt the formation of some new lines that could now offer a specialized service. One of the first of these was the New York-Philadelphia-Washington Airways which was popularly known as the "Ludington Line," a million-dollar company headed by C. T. Ludington. The line, buying the first batch to come off the production line, operated 7 of the SM-6000 liners between New York and Washington, D. C., giving one hour service on a schedule of 11 round trips daily. "Every hour on the hour" became their operating slogan. Business soon flourished to the rate of 150 passengers daily, and in the space of a few months, thousands of round trips had been recorded. One would certainly think that a hi-motored airplane in this price range would necessarily be a stripped- down vehicle devoid of normal comforts and conveniences but surprisingly this was not the case with the Stinson "Air Liner"; it was well arranged and well appointed in coach-style comfort for the shorter trips. Because of the nature of this frequent service to New York and Washington, the crew was limited to a pilot only and he was required to do everything. He would take tickets at the plane's door, see that passengers were seated properly and comfortably, fly the ship to its destination, supervise the unloading, and repeat this routine for the return trip. "Ludington Line" pilots were surely kept busy but none seemed to mind being glorified aerial bus-drivers. With increasing business the line added more equipment and the operating fleet soon comprised 10 of the Stinson (SM-6000) "Air Liner".
Though shrouded in some mystery because of the span of time involved, it has been generally conceded that the Stinson "Tri-Motor" was a redesigned development of the "Corman" Tri-Motor. The Corman company was a trade-name arrived at by mating the names of E. L. Cord and L. B. Manning who were president and V. P. of the Cord Corp. As the Corman Aircraft Corp. of Dayton, 0., the company built one or two examples of the "Corman 3000" and "Corman 6000", then turned over the task of redesigning this craft for quantity production to the engineers at Stinson Aircraft. The basic "Corman" as a 7 pla6e craft was powered with three Wright "Whirlwind" J5 engines of 220 h.p. each, but Stinson had better access to Lycoming engines now so these were used in the SM-6000 series. Regardless of the fact that the SM-6000 was supposed to be a development of the earlier "Corman" design, it shows clearly that many great changes took place in the redesigning, and the new "fri-motor" configuration came out looking just as "Stinson as Stinson could be".
The Stinson "Air Liner" model SM-6000 was a large high-winged cabin monoplane of the tri- motored type with seating for eleven in its spacious interior. As developed in the first batch of this series, the "Air Liner" was arranged for coach-type service on the shorter routes; later versions (SM-6000-A and SM-6000-B) in this series were available in several arrangements, including a "Custom Club" special. Early examples of the SM-6000 had bare engines but low drag "Townend-ring" fairings were soon available, as were wheel streamlines over the large wheels to boost cruising speeds a little higher. Powered with 3 nine cyl. Lycoming R-680 engines of 215 h.p. each, the big SM-6000 delivered a performance that belied its well apparent bulk; a fully loaded take off required only some 700 feet and the landing roll hardly ever exceeded 400 feet. It is this short-field performance plus the ability to carry a sizeable payload that prolonged its useful life, so we find it not surprising that at least 25 of the high-wing "Stinson Tn-Motors" were still flying in active service up to 10 years later. The typ.e certificate number for the 11 place model SM-6000 was issued 7-10-30 and at least 10 examples of this particular version were manufactured by the Stinson Aircraft Corp. at Wayne, Mich. "Eddie" Stinson, master pilot, was the president of the company but he was rather hard to catch at his desk because he spent most of his time in the shop or flying around the countryside promoting "Stinson" airplanes.
Listed below are specifications and performance data for the Stinson "Air Liner" model SM- 6000, as powered with 3 Lycoming R-680 engines of 215 h.p. each: length overall 42'10"; height overall 12'0"; wing span 60'0"; wing chord 105"; total wing area 490 sq. ft.; airfoil Goettingen 398; wt. empty 5575 [5625] lbs.; useful load 2825 [2875] lbs.; payload with 120 gal. fuel was 1815 [1865) lbs.; baggage 165 [215] lbs.; gross wt. 8400 [8500] lbs.; figures in brackets as eligible with radio installation; max. speed 138; cruising speed 115; landing speed 60; climb 1000 ft. first mm. at sea level; climb to 10,000 ft, was 25 mm.; ceiling 15,000 & 14,500 ft.; gas cap. 120 gal.; oil cap. 15 gal.; cruising range at 36 gal. per hour was 345 miles; normal price at the factory was $23,900 with special price announced at $18,000 for short time only.
The fuselage framework was built up of welded chrome-moly steel tubing, faired to shape with formers and fairing strips then fabric covered; the whole forward section to a point just behind the pilot's station was covered in dural metal sheet panels. The pilot's compartment had seating for two side by side and the main cabin was arranged for the seating of ten; a large entry door to the main cabin was on the right side to the rear. The wing framework, in two halves, was built up of chrome-moly steel tube spar beams that were welded into Warren truss girders with wing ribs riveted together of square duralumin tubing; the leading edges were covered with dural metal sheet and the completed framework was covered in fabric. Gravity-feed fuel tanks were mounted in the root ends of each wing half. The wing was braced by two parallel struts on each side and the engine nacelles were mounted to a truss connected to the wing braces; from this extended the landing gear which was of unusually wide tread. The husky landing gear used "Aerol" (air-oil) shock absorbing struts, wheels were 36x8 and Bendix brakes were standard equipment; a swivel-type tail wheel was mounted far aft for better ground maneuvering. The fabric covered tail-group was built up of welded chrome-moly and 1025 steel tubing; the rudder was aerodynamically balanced and the horizontal stabilizer was adjustable in flight. Metal propellers, exhaust collector-rings, electric inertia-type engine starters, wheel brakes and a tail wheel were standard equipment. The next development in the Stinson "Tri-Motor" series was the improved model SM-6000-A as described in the chapter for ATC # 367 in this volume.
Listed below are Stinson model SM-6000 entries as gleaned from registration records:
NC-974W; SM-6000 (# 5005)3 Lyc. R-680
NO.975W; " (#5006)
NC-976W; " (#5007)
NG-977W; " (#5008)
NC-978W; " (#5009)
NG-979W; " (#5010)
NG-429Y; " (#5011)
NC-429Y; " (#5012)
NC-497Y; " (#5013)
NC-498Y; " (# 5014)
This certificate for serial #5005 through #5014; approval expired 7-1-32.

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