The partners involved with Inland Aviation Company began to dissolve when George Willet split for Lemoore and began his own business at the old USAAC base 9-miles southwest of the city. A portion of the old base is still there and located off highway 198 just west of the main entrance to NAS Lemoore. Willet had several ag modified Stearman aircraft along with a Spartan 7W. I recall seeing a complete but disassembled stock Stearman still in original AAC colors of blue and yellow in a side room off the main hangar.
Willet was the first person to successfully equip a Stearman with a complete electrical system with high intensity lights to fly at night. He used a 24 volt electrical system with a 50-amp engine driven generator and large landing lights mounted on the interplane struts, one on each side point forward and one on each side pointing outboard at a 45 degree angle to light up the ground when making turns.
Inland Aircraft Company dissolved around 1950. George Willet had already left and Tom Jergenson went to the Bakersfield area to establish a company he called Inland Crop Dusters. Barney Negra stayed at Inland and continued to operate the business. Stearman eventually gravitated back to the Lockheed Aircraft Corporation in Burbank, rejoining the firm in 1955 as a Senior Design Specialist working on a design for switchblade winged airplanes, vertical take-off and landing projects and re-entry space vehicles.
The story goes that a middle-aged man walked into the employment office one day in June 1955 and made an application to join the company. That man filled out the form and left. After receiving the form and reviewing it, the person behind the counter was startled to see the name Stear-man and immediately called Hall Hibbard, senior vice president. Lloyd Stearman was immediately hired.
Stearman retired from Lockheed in 1968 but reformed the Stearman Aircraft Corporation in the Los Angeles area still determined to develop a new turboprop powered agricultural airplane he designated the MP-1. It is possible that this new airplane was similar to his original SA-1 design, but there is no data to confirm this hypothesis. But surely he had retained the original pencil drawings of the SA-1 that were on vellum drawing paper after leaving the first copy blueprints in Dos Palos. Stearman’s health began to fail which ultimately forced Lloyd to stop design work on the MP-1 and, just like the previous SA- 1 design, none were ever built. Stearman lost his battle with cancer and died on April 3, 1975 in Northridge, California. His career spanned more than 50-years and during that time he earned the respect and admiration of the aviation community that he helped to create.
In the box of drawings was a single page with the Stearman Engineering Company identified in the title block and signed by Walter C. Clayton that was a complete list of drawings and numbers revised April 27, 1945. It shows drawing numbers C-012 through C-025 and drawings D-022, sheet 1 and 2. Other pages are missing except for this page 3. Drawing list was contained in Report No. 8.
It is interesting to note that Lloyd Stearman had planned to use “off the shelf” and proven components for his SA-1 design, such as Aerol shock struts manufactured by the Cleveland Pneumatic Company, the Pratt and Whitney R-985AN-1, AN-3 or – 14B engine, wheels and brakes from Cleveland Tire and Rubber Company and Hayes Industries.
All Stearman Aircraft drawings pertain to the model 75 series from the A75N1 to the E75N1. The Boeing Airplane Company, Wichita Division pertain mostly to the model 75 aircraft, however drawing 120-3001 pertains to the model AT-15 and is an oil tank of 12-gallon capacity, obviously a large multi-engine aircraft with two tanks required per airplane.
In Fig.1, we see a side view of the ship as photo is taken above the blueprint. Creases are where drawing has been carefully folded for almost 80-years. The drawing is to scale – note how the large airplane makes the Pratt Whitney R-985 look very small. Stearman also considered the Continental GR- 975-A engine that produced 525 take-off Brake Horse Power (BHP) at 2500 rpm for five minutes and 500 BHP normal rated power at 2500 rpm at 5,000 feet. In Fig.2, we see a front view of SA-1 showing outrigger landing gear. Dihedral in lower wings is 4- degrees. In this drawing the lower wingspan looks to be slighter greater than the upper wingspan. Lloyd Stearman chose the NACA 4415 airfoil for the SA-1, a very nice forgiving high lift airfoil. When Grumman designed the G-164 Ag Cat in 1955 they chose a NACA 4412 airfoil, the difference being mainly thickness. Obviously Lloyd knew something about high lift airfoils back in 1944.
Title block for Stearman Engineering Company’s drawing C-007 showing the signature of Lloyd Stearman who approved this drawing. This is the only drawing compiled that had the signature of Lloyd Stearman in the entire collection.
Details of construction drawings show interesting comparisons to the Boeing Model 75 aircraft. Construction details show the following:
Basic 4130 Chromoly tubing gas welded. Upper longeron is 1-1/4” X .058”, reduced to 1-1/8” X .049”, reduced to 1” X .049” and finally 7/8” X .049” aft of the rear cockpit. Lower longerons are 1-1/8” X .058, reduced to 1” X .049 and finally 7/ 8” X .049 aft to the tail post.
Legs are constructed of 4130 tubing measuring 1-1/8” X .065”, 1” X .065” and 7?8” X .065” and the ring is 1-1/8” X .065” turned to a center line diameter of 26.12”. It is attached to the fuselage frame using four 1/2 –20 undrilled bolts 2-7/8” long.
WINGS AND CENTER SECTION
Basic Spruce and plywood construction similar to the Model 75 production airplanes. Spars are 1-1/4” thick Spruce and are routed between ribs to save weight. VERTICAL FIN Basic Spruce and plywood construction. Front and rear spars are 3/ 4” thick Spruce and the entire surface is covered with .062” thick Mahogany plywood with grain parallel to leading edge.
Basic Spruce and plywood construction. Front spar is built-up with 4-laminations of 1/4” thick Spruce. Rear spar is 3/4” solid Spruce. Entire structure is covered with 1/16” Mahogany plywood with grain direction parallel to leading edge.
Built-up aluminum structure using 24ST (2024-T3) Alclad sheet. Entire structure is skinned with .050” 24ST aluminum. ELEVATORS Built-up aluminum structure using 24ST (2024-T3) Alclad sheet. Entire structure is skinned with .050” 24ST aluminum.
Built-up from 4130 steel tubing. Spar is 1-1/8” X .049”, ribs are 1/4” X .028” 4130 steel tube and trailing edge is 1/4” X.028” 4130 tubing.
WING STRUTS All
4130 steel streamline tube construction, unlike the aluminum struts used on the Model 75.
LANDING GEAR AND SHOCK STRUTS
Oleo (air/oil) shock struts from Chicago Pneumatic.
WHEELS AND BRAKES
Undecided on exactly what off-the-shelf wheel and brake assemblies to use. However drawings for 7.50 X 10 were common along with single disc, drum type and expander tube type drawings are included. Manufacturer’s are Bendix, Hayes and Goodyear. Tail wheel drawing was from Goodyear for a 4” Airwheel Hub. Master cylinders from Wagner Electric Company showing a 1-1/4” diameter by 1- 5/8” stroke aircraft master cylinder.
In Fig.3 pictured above, near the end of production of the basic model 75 Boeing Stearman design, a few aircraft were built with spring steel landing gears. I recall seeing one of these ships in the rafters of a hangar owned by Doug Gandy who had an Ag operation near Raisin City in California’s central San Joaquin Valley back in 1959. I do not know what happened to the airplane but there could not have been very many of these rare aircraft that managed to get into civilian license. The aircraft above has been highly modified to incorporate a 450 hp Pratt and Whitney R-985 engine and a closed canopy for pilot comfort. It was these Boeing Stearman aircraft that put an end to Lloyd’s SA-1 design. These drawings represent a glimpse into aircraft design in the 1940’s, a time when aviation was constantly moving forward. Lloyd Stearman was a pillar in the aviation community, designing and constructing aircraft that bore his name, a dream of any person involved in aviation to establish such a credible contribution.