In Norman, OK from left to right: Ted Smith, Rufus Amis and George Lynn Cross, President of Oklahoma University. For his book Stars and Commanders, Dave Duntz conducted years of research, including with Ted Smith’s unpublished memoir. The memoir is presented in part here, as Chapter 15 in Duntz’s book. You can purchase Duntz’s book at www.starsandcommanders.com.
“Toward the middle of 1954 I foresaw that my talents could best be devoted to the R&D area continuing to improve the Aero Commander as well as look to the future. We have found, over the years, that a continuing R&D program is a necessary function in any product whether it be aircraft or any other to stay ahead of the competition. We were on top and it was my desire and the desire of the Company to stay there. It was my strong belief that R&D should be entirely divorced from on-going production in every way, working independently on a budget authorized by management. It was in August 1954 that I changed my position from General Manager of the production operation to Vice President of Engineering and R&D. We leased a portion of a hangar from Oklahoma University located on Max Westheimer Field in Norman, Oklahoma. The hangar was a former World War II building, all of wood construction, and was badly in need of repair. Arrangements were made with the University to refurbish and upgrade the building with painting and general clean-up and lighting for the engineering room and offices upstairs and the R&D shop on the main floor. We installed equipment for the shop area and brought airplane serial number 88, “Ole 88” as she was called, to use as the prototype for future projects. Again, we started with a very meager crew—a few engineers and some mechanics, all handpicked for their individual genius ability. Ward Fuller acted as project engineer who had come with us from Douglas in 1952, along with Richard McIntruff, one of the original 11 people from California and me, and several others. I believe we had 10 or 11 people. In two years, we had 50 or more and by the time the jet program started in 1959, we had over 100 in Norman.
Our dream to build a true business aircraft had succeeded and we were gaining ground rapidly in production but were still pioneering. Other companies were beginning to see the picture too and follow in our footsteps: Beech with their Model 50 Twin Bonanza, Cessna had announced the 310, but Aero Commander was the leader and had pioneered the idea of a true business aircraft which by now was being accepted all over the world. Big companies were buying the Aero Commander: I.B.M., John Deere Company, Magnolia Oil Company in Dallas, Texas, North American, Douglas, L.T.V., Rockwell Standard, and many more. But it was now the responsibility of the R&D Division to keep that reputation of the Aero Commander on top. We had the pleasure of a visit from Mr. Charles Kettering, the genius of General Motors, to our factory in Bethany. He said to me during his visit, “Ted, you have created a product born from a dream. From here on out it is only the pick and shovel work to be done to produce the product. Your creative genius should not be involved in the everyday production on pick and shovel work, but you should direct your thoughts and efforts to the future.” These words of advisement from a great and successful man have remained with me from that day. They were probably one of the incentives for wanting to set up the R&D facility at Norman to continue in the field I knew and liked best: the creative art of aircraft design—something that was God gifted. The magnificent future lay ahead, the future was placed on my shoulders and the shoulders of the new R&D group at Norman.
By this time, I had obtained my multi-engine rating and had accumulated hundreds of hours with Bert as co-pilot in engineering flight test work. I had obtained a feel for this other segment of engineering and a most interesting part of aeronautical engineering. I had taken part in the original certification programs as well as the certification of the 520 and 560 models and by now felt confident in doing part of the engineering flight test work myself.
On that Sunday afternoon February 22, 1953, when I obtained my multi-engine rating from Jack Blanchard, an authorized F.A.A. flight examiner, we celebrated a little by taking my family for a ride in the Aero Commander. Here I was, flying in the aircraft that not long before had just been a dream—then sketches—the prototype to follow—and now here we were with my family, flying around the skies of Oklahoma in the 44th production Aero Commander. It was a thrill that words cannot describe, nor could one express in words that inward feeling of self-satisfaction and accomplishment.
Ted Smith takes his mother for a flight in an Aero Commander.
Bert had by now left the Company and returned to California to join North American Aviation as an engineering flight test pilot on the North American F-86.
One of the greatest thrills was to learn that Douglas Aircraft Company had ordered some Aero Commanders for Executive use—also North American, Lockheed, Martin, and McDonnel Aircraft. Businesses large and small were taking to the idea of having their own business transportation and flying on their own schedules.
In 1954 I was in my third decade of being affiliated with aviation, and here I was in Norman, Oklahoma with a responsibility to keep a company—my dream company—headed forward in the proper direction to keep the name Aero Commander the leader—the pioneer—keeping the product ahead of all others to remain number one in the marketplace.
The Model 560 was the first in the industry with a three-blade propeller, one of the many items pioneered by Aero Commander. Along with the Hartzell Propeller Company, we developed the first in the industry for the lower powered engines, the first constant speed full-feathering propeller. As a prelude to the first oil-controlled feathering propeller, Dave Bierman and Dick Grimes of the Hartzell Propeller Company, at our request developed a mechanical one. This consisted of providing interference pins that were connected through cable and guides to the pilot and co-pilot station in the aircraft. By pulling hard on one or the other of the cables, it would place the interference pin in position so that as the stop for the blade on the hub of the propeller came in contact with the interference pin, the stop would shear and the aerodynamic forces on the blades would place them in a feathered position. Crude, but effective. One day when Bert and I were flying the “Blue Goose” form Norman to Bethany, the cable with pin attached accidentally engaged and, since the engine was running at cruise power, the sudden swoosh of the propeller feathering startled both of us for a few seconds. But, we did find out the feathering device did work.
It was not too long after the mechanical feathering was installed that Hartzell developed one that was oil pressure controlled. It was still being used on current aircraft today where the propeller handle is pulled all the way back through a detent in the control quadrant releasing the oil pressure in the dome of the propeller. Aerodynamic forces, acting on the blades and with the help of the counterweights force the blades of the propeller into an 87-degree angle for feather. This method of feathering has one other advantage in that in case of engine oil pressure failure in the engine which supplies the oil pressure to the propeller dome, the propeller will immediately feather. A great safety feature that has saved airplanes from fatal accidents since almost instantaneous feathering is obtained upon loss of oil pressure in the engine. One case in particular is remembered, when an Aero Commander lost oil pressure upon takeoff with a full load of passengers and fuel but was able to return to the field and make a safe landing because of the instantaneous feathering of the propeller which reduced aerodynamic drag of the airplane sufficiently so a safe go around could be accomplished.
Strain gauge test on a 3-blade propeller with a fixed rod holding the apparatus. Photo from the Ron Smith Collection.
The start of the R&D Division at Norman, Oklahoma gave us advantages that were a valuable asset to our growth: We had access to the Oklahoma University’s aeronautical facilities, and we were able to hire, during vacation periods, certain of the staff from the Aeronautical School. One prominent and respected professor, whom we used as a consultant as well as having him with us on a full-time basis during vacation times, was Professor L.A. Comp. “Doc Comp,” as we called him, headed up the aeronautical section at Oklahoma University. Doc, as most professors are, was purely a technical man but was also in many ways very practical. Doc almost singlehandedly and only with the part time help of some of his students, built a small wind tunnel for the Aeronautical School, innovated many other practical and realistic things for the aeronautical students and gave us a great deal of help in our R&D programs.
People will not believe that the Aero Commander reached its peak production in 1956 in the original 20,000 square-foot hangar on Tulakes Airport. However, we did have a small supplementary hangar on Cimarron Field in Yukon, Oklahoma about 15 miles west of the factory where all of the options were installed.
Late in 1952 Mr. & Mrs. Bill Horton from Houston, Texas visited us in Bethany and asked if they could take on the contract for upholstering the planes. Up to now, we were doing it locally. We gave Bill and Dorothy Horton a chance to see what they could do. So, they rented a small facility in Bethany and started. Just the two of them at first. Then they hired a couple of others, and we helped them in preparation, etc. Their work proved so successful that they set up a rather large facility in Houston, Texas and we also contracted with them to do the painting. We were ferrying the airplanes back and forth between Bethany and Houston for some period of time. Then finally, Bill and Dorothy wanted to branch out and take on other work in addition to the Aero Commander and moved to a larger hangar facility on Meacham Field in Fort Worth, Texas. This was good for Aero Design because it cut the ferry distance in half. Dorothy and Bill Horton became known as Horton and Horton, eventually becoming known world-wide as one of the finest custom interior and paint shops.
Previous to setting up the R&D division there were two items that I felt would greatly improve the Aero Commander capability and further attract sales: First, would be a supercharged engine version that would permit the aircraft to obtain higher speeds by going to altitudes about 10,000 feet, and second, to someday have a pressurized version with the supercharged engine.
Our first undertaking at the R&D Division was the development of the supercharged engine series. Its initial designation was 680 Super. Availability of engines in any new aircraft project is the master key to the project. In so many cases power plants have paced the aircraft designer’s ability to design an aircraft project that he may have in mind. This was the case with the 680. We knew what we wanted, but no engine to provide the supercharged power.
Clarence had been thinking about the idea of supercharging the G0480—the engine then being used in the 560 series—260 H.P. normal rating and 280 H.P. takeoff rating. By supercharging this series; it appeared that the power could be increased to a higher rating instead of being a sea level rated engine, the critical altitude could be increased up to around 12,000 to 14,000 feet and operating altitudes of 25,000 to 30,000 feet could be reached with the airplane since full-rated power could be maintained to the 12,000 to 14,000 feet range.
Supercharged engines were not new at this time. Since World War II airplanes with their very powerful engines were supercharged to operate at high altitudes. Supercharging the small engine would be another breakthrough for business aircraft. Higher performance could be obtained at lower altitudes as well as higher altitudes using oxygen for the passengers. It would be possible to fly over weather at 16,000 to 20,000 feet. Supercharging would permit the aircraft to carry out mapping missions at 25,000 feet or higher and offer single engine ceilings up to 14,000 or 15,000 feet—another breakthrough coupled with a great added safety factor when operating under instrument conditions or in clear weather. The greater safety offered under an engine out condition would be of great importance and offer an added sales tool.
We approached our friends at Lycoming in Williamsport, Pennsylvania with our requirements and Clarence was very enthusiastic about moving forward with supercharging the G0480 series. Conferences were held with Clarence, Ray Cowden, and Floyd Bird and agreements were reached at that point that Lycoming would proceed to develop the supercharger for the G0480 series of engines and that we at Aero Commander would be a priority customer. We would also furnish the engineering flight test bed on our R&D airplane for the first two non-certificated supercharged engines while Lycoming proceeded to build a test stand article and to tool up for production. We gave Lycoming an indication that once in production we could foresee a market for the supercharged version of the Aero Commander of at least 100-150 aircraft per year. This preliminary estimate as we shall learn later was very conservative, but we shall also learn that the problems encountered with the airplane engine combination as a production unit became a great burden for both companies. However, on the more positive side, after the production problems were cured, the project turned into one of the most successful for both Aero Design and Lycoming.
Lycoming furnished us two prototype engines in early 1955. We had completed the engineering for the installation and made the first flights a short time later. The prototype engines performed beautifully. They were rated at 340 H.P. for takeoff with 48 inches of manifold pressure and 3400 R.P.M. and for continuous rating they were 320 H.P. at 3200 R.P.M. and 45 inches of manifold pressure. The engines were geared the same as the G.O.480 series (66 to one), which gave a propeller speed of 2250 R.P.M. at takeoff power, 2150 R.P.M. at normal rated power, and when cruising the engine at 2600 R.P.M. and 32 inches of manifold pressure, the propeller speed was down to 1725 R.P.M. This made for a decently quiet cabin in the cruise configuration and gave higher thrust horsepower because of the increased propulsive efficiency of the propeller operating at the lower R.P.M.
The engine had a dry weight of 495 pounds. It had a dry sump that required a separate oil tank installed away from the engine compartment. A five-gallon bladder cell was installed in a cavity directly behind the engine to meet the requirement. It was contemplated that additional fuel would be required for range, so we designed the section of wing outboard of the nacelles as cavities for two additional fuel bags giving a capacity each side of 33 more gallons of fuel. These tanks were pure auxiliary tanks, independent of the main five tank system. Fuel was fed to each engine from the auxiliaries through independent fuel system components—their own system electric fuel selector valves and with their own electric fuel boost pumps. No cross feed of fuel was provided with auxiliary tanks.
This new series in the Aero Commander line was to be known as the 680 Model and its counterpart with increased H.P. non-supercharged engines was called the 560A. The power in this series was 260 H.P. normal and 280 H.P. for takeoff. Gross weight of the 680 was 7,000 pounds and the 560A, 6,000 pounds.
I flew many hours of engineering flight test in serial Number 88 with the new supercharged engines. On one occasion I had a malfunction that came close to causing a crash landing. While flying at 10,000 feet, I saw smoke coming out of the right nacelle and then almost immediately flames – an engine fire—the one thing feared by all pilots! Fire in the air!
I was about 30 miles south of Norman at that time. I immediately shut the engine down, feathered the propeller, and started a descent simultaneously calling Will Rogers Tower, telling of my predicament and that I might need fire equipment to stand by. They acknowledged in the affirmative and would await further word. I made my descent rather steep to get as much airflow through the engine as possible and, when over Norman, it appeared that the actions taken had caused the fire to recede considerably. I called Will Rogers again and told them I was landing at Norman in that I felt a safe landing could be accomplished and no fire equipment appeared to be necessary. The prototype engine mounts were made of steel so I felt with the fire retarded now, the engine would not drop from the mounts.
I made my landing at Norman, taxied over to the hangar, and the boys opened the cowls for inspection. The entire engine aft section was partially burned away. Fire damage had ruined most of the accessories, electrical and hydraulic, and vacuum hoses including fuel hoses and parts of the engine nacelle had large burned-out places. The fire was caused when the rear supercharger bearing seized. This caused the supercharger shaft to become red hot. Sparks then ignited the magnesium housing surrounding the supercharger wheel.
Lycoming redesigned the bearing section of the supercharger shaft and in time the redesign proved to be almost satisfactory, but only completely satisfactory after another modification or two plus a change in material of the shaft and bearing. As an added precaution, however, we had Lycoming provide a thermocouple at the bearing with a temperature read out on the pilot’s panel that would provide an immediate warning to the pilot in case of overheat of the bearing and sufficient time would then be available for the pilot to shut the engine down before fire or extreme damage to the bearing and housing could occur.
The Model 680 series and 560A series of the Aero Commander incorporated many refinements along with the change to the new engines.
The entire cowling and nacelle were redesigned so that the augmenter tube lips were nicely flush with the firewall to provide a smooth entry of the exhaust gases into the augmenter tubes without creating turbulence. Heretofore they had been installed with the leading edge of the augmenter tube extending about three inches forward of the firewall and, therefore, causing turbulence and a loss in efficiency. The entire induction system was redesigned providing dual inlets at the front face of the dowl with each air inlet having its own air filter. The dual inlets were built as integral parts of the lower cowl. Both inlets transitioned into an aluminum alloy casting which also contained provisions for heater air to be drawn from heater muffs around the exhaust pipes both sides. As a precaution, we added a pop-off valve in the ducts along each side of the lower cowling that would automatically open and provide the engine with an alternate air source in case the air filters became clogged or if the heater air source became inoperative for any reason.
The dual inlets were chosen so that the previous problem of poor distribution could be overcome by a balanced air inlet system to the carburetor. In tests, this proved to be a real solution to the previous problem experienced with the 520 heretofore explained and, in addition, gave us an increase of ram pressure to the carburetor of almost one inch in manifold pressure which gave the 560A added efficiency.
The cowlings and nacelles were widened enough to let us bury the augmenter tubes inside the nacelle except for the extreme aft end of the tube where this portion was left exposed so as not to interfere with the exhaust from the six-inch diameter tubes.
The new nacelles and buried augmenter tubes cleaned up the nacelle area not only aerodynamically but gave a much nicer appearance from an aesthetic standpoint.
The forward cabin was lengthened ten inches to provide additional cabin comfort, giving the opportunity of a longer pitch for seat spacing.
We continued to build up time and evaluate the new supercharged engine and paralleling our R&D program we were feeding Bethany-Production engineering for the changes and they in turn were building tooling and preparing for the production of the new series.
Application for type certification for the new models was made to the Fort Worth region of the F.A.A. and a type certificate was granted to Aero Design & Engineering Company on October 14, 1955, after we had completed 250 hours of service time using two aircraft: One was our R&D prototype which had production engines installed, and another production airplane, serial Number 242. This was later kept at the R&D division at Norman as another R&D aircraft incorporating all of the latest changes. We flew both airplanes around the clock and completed the 250 hours of service time within about two weeks. Since the airplanes were operated under more or less controlled conditions and by pilots who, by now, had learned to operate the supercharged engines, we experienced no problems whatsoever. Therefore, what follows, outlining the many problems in the field after production deliveries were started, came as a great blow to both Lycoming and us. Deliveries continued, but field problems began to rise at a very high rate.
We found many pilots who had been accustomed to moving the throttle to the full forward position for takeoff with an unboosted engine, were doing the same thing with the supercharged engine. This boosted the engine to 60 or 65 inches of manifold pressure at takeoff causing valves to burn, pistons to collapse and/or burn, cylinders and heads to loosen, as well as causing internal damage to the engine. These problems could be segregated to the pilot error phase, but unfortunately the same type of problems began to crop up with normal operation of the engines. We did have some recurrences in some instances with the supercharger bearing, but the temperature gauge gave warning of this and to my knowledge no occurrences of engine fire, as I had experienced during test flight in our engineering prototype Serial Number 88.
Again, we were faced with working around the clock to resolve the problems in the field. We put four additional production airplanes in service. Lycoming representatives were working with us. It was a mutual problem of a very serious nature. Lycoming made studies of engines running on the test stands in Williamsport, flying production engines with each engine instrumented to measure brake mean effective pressure—checking for temperatures—detonation—having various oil companies’ fuels analyzed for octane rating and lead content, as well as many other independent laboratory tests made of the fuels. In this respect we did find variances.
Lycoming did some redesign work—one of them being the change-over to salt-cooled valves, redesign of piston head domes, design improvements in the supercharger, beefing up the connecting rods and other miscellaneous parts of the engine.
In about six months things began to clear up but believe me it was a very hectic six months. Again people—dedicated people intensely realizing the importance of curing the problems at hand. In reality, it was a case of survival for both us and for Lycoming. At that time the Aero Commander was Lycoming’s prime customer and neither company could afford to turn their backs on the problems at hand. When it was all over, Lycoming and Aero Design were closer than ever and from that time forward we pretty much worked together in developing engines for the constant upgrading of the Aero Commander and in turn opened up greater market potential for Lycoming.
I remember clearly the summer of 1956 when the Lycoming plant was on strike and the supervisory people at the plant were out in the shop assembling engines to keep Aero Design from having to close down for lack of engines. We set up two production airplanes just off the production line—bare of interior with just the pilot and co-pilot seats installed—laid plywood over the cabin floor with provisions for strapping down and carrying two engines. We flew these airplanes to Williamsport on a regular schedule to bring back two engines in each aircraft and I recall with fond memory flying many of the trips personally. By this period in time, we were building at a rate of 18-20 airplanes per month—a much sought after aircraft in the market place even though in the beginning of the 680 series both companies came very close to the brink of disaster.
Public announcement of the 680 series was made by press release on September 3, 1955, and deliveries started in early 1956.
Model 680 takes to the air. Aero Design photo by Wayne Entrekin.
