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Ted Smith Aerostar
Piper PA-60 Sequoya 602P

 

Ted Smith sold his interest in Aero Commander to Rockwell and by 1966 had completed the first mockup of the Aerostar and production commenced, with finance from American Cement, at Van Nuys. Ted Smith then sold out to the American Cement Company, which, Smith says, simply didn't know how to run an aircraft business and consequently ran Aerostar into the ground before finally selling out to Butler Aviation, another firm with no experience in manufacture. Butler did nothing with the Aerostar, and eventually, Smith was able to buy back the company and a large inventory of parts at a much lower price than that at which he had sold out in the first place. This sequence of events is crucial; it amounted to a huge gift to Smith, who found himself able to sell a comparatively exotic airplane of excellent performance at unnaturally low prices, because he obtained his parts - enough of them to make hundreds of airplanes in some cases - at a huge discount. Thus, after only a short time in business, Smith could boast of a 10-percent annual return (before taxes), one of the highest in the industry.

 

 

The prototype first flew in 1966 and had 180-horsepower engines, but the airframe was designed to take various powerplants up to turbines without major changes. The 290-hp Lycoming IO-540, used on the first production airplane delivered in 1968, was available on Aerostars in a normally aspirated or a turbocharged version.

 

The three Piper Aerostars - the non-turbocharged 600, turbocharged 601 B and pressurized 601P - are virtually identical in appearance. Heavy, butt-joined and flush-riveted skins give the airplane an extremely smooth surface, and the thicker than usual gauge metal serves two purposes. Its extra strength reduces the amount of internal structure needed, and it deforms less during flight to more accurately retain its aerodynamic shape.

Aerostars all have power steering. The nosewheel is turned by pressing the left or right side of a spring-loaded rocker switch on the center console. The switch actuates a solenoid that directs hydraulic system pressure to a combination shimmy damper/steering cylinder on the nosewheel. The controls are connected by push-pull rods.

The right engine on the Aerostar has the only hydraulic pump, which supplies pressure for the gear, flaps and power steering. To retract the gear after a right engine failure, the propeller must be allowed to windmill for eight seconds to provide sufficient hydraulic pressure. An extended gear subtracts 300 fpm from the rate of climb. A single-engine go-around with the right engine dead would be extremely difficult. The optional electric hydraulic backup pump would seem a desirable investment.

There are no up-locks on the gear. It is held in the retracted position by hydraulic pressure and by a pressure accumulator should the pump fail.

Smith designed the fuel system to be as simple as possible. There is a 42-USgallon fuselage tank behind the cabin and a wet wing cell on each side extending from the engine nacelle to the wingtip. Because of the thin, laminar-flow wing, these tanks are long and shallow. They each hold 66.25 USgallons usable, for a total usable capacity of 174.5 USG. The fuel gauge displays the total capacity of the three tanks; by moving a spring-loaded toggle switch, you can read the capacity of either wing tank. To obtain the quantity of the center tank, you must subtract the amount in each wing tank from the total readout.

The electrically operated fuel valves (one for each engine) have three positions - on, off and crossfeed. With the selectors "on," each engine draws from both the center tank and its own wing tank. The system is arranged so that the wing tanks will run out first, leaving the center tank to feed the remaining fuel to both engines. The intent was that for normal operations the pilot would select ‘on,' and forget about fuel management.

The Aerostar has standard leather upholstery covering bucket seats. Most used 600s and 601s have a brake mod which apparently remedied a pad deficiency in the original system. The fuselage: four longerons, widely spaced frames, heavy skins, butt joints, all rivets machine-counter-sunk and shaved, wide open spaces of unsupported panel. In a departure from classical design practice, Smith designed his structures with skins one or two gauges thicker than are commonly used, and with fewer than the usual number of frames and longerons. Stringers stiffeners riveted across wide sheet panels to prevent buckling are omitted entirely. Smith’s rationale was that some of the added skin weight would be made up by eliminating many detail parts; and that thick skins could be depended on to provide strength in compression, while thin ones could not. Thick skins would make the wing stiff enough to be free of flutter at jet speeds, despite a laminar airfoil thin enough to have a fairly high critical mach number. The tail feathers are interchangeable. All the control surfaces are moved by push-pull tubes; there is no aileron trim — fuel is crossfed to correct wing heaviness — and yaw and pitch trim are electric, with gearhead motors providing part of the control surface balance. Mammoth fittings and pins in quadruple shear connect the wing box to the fuselage at four points. The wing box passes through the fuselage just behind the last pair of seats; above it is a large hat shelf, and behind it a fuel tank. Still farther aft in the fuselage is the luggage compartment, situated at shoulder level. The entire cabin is ahead of the wing spar.  The wing loading is high, 32.4 lb/sq ft at gross in the normally aspirated Model 600, whose gross weight is 5500 pounds. The fuel system is controlled by motor-driven electric valves which take their cues from three-position rotary switches on the panel: Off, On, Crossfeed. Normally, each engine feeds from,its wing and the fuselage tank; on crossfeed, it would feed from the opposite wing tank only. Fuel is taken in through three fillers, one in the fuselage and two at the wing tips (the entire wing outboard of the engine nacelles is wet), and all three sumps are drained at a convenient point on the underside of the tail cone. All hydraulic pressure, in the standard version of the system, is provided by a pump on the right engine. A small accumulator in the tail cone provides standby power in emergencies. Hydraulic power is used for the gear, flaps, and nosewheel steering. The nosewheel steering system consists of a rocker switch on a center subpanel (which also has the trim switches) which directs a restricted flow of hydraulic fluid to either side of the shimmy dampener, depending which way you want to turn. Holding the rocker switch down feeds fluid to the appropriate side, turning the nosewheel in proportion to the time the switch is held depressed. Since it is the nature of a shimmy dampener to permit controlled leakage from one side of the piston to the other, the nosewheel tends to center itself gradually once deflected. A steering failure is therefore not critical; the airplane can be steered with brakes.

The 601A became the B model in 1977 with the addition of 15 inches to each wingtip for increased stability at high altitudes, automatic rather than manual wastegate controls and a 300-pound gross weight increase. The 1978 model has an improved wastegate that is more durable and efficient, resulting in an increase of critical altitude from 16,000 to 23,000 feet.

The first 601P rolled off the production line in May 1974, as a 1975 model. The first 601P had "short” wings, with a span of just over 34 feet. The factory extended the wings early in the production run and virtually all of the airplanes built with less span were redone by the factory to the new 36.67 foot wingspan. Maximum cruise on the first 601P was shown in the pilot's operating handbook as 256 knots at 25,000 feet.

By 1970 the plant was too small, and through lack of capital, the Aerostar type certificate was sold to Bulter Aviation. Production was carried out for them by Mooney as ‘”Mooney Aerostars”. On 7 December 1972, Ted Smith & Associates was formed with Butler Aviation to continue Aerostar production, which by 1975 it was in full production in California in three versions, the normal 600 series, the turbo-charged 601 and the pressurised 601P, and remained until the death of Ted Smith and subsequent sale of all rights to Piper, on 27 March 1978.

The Aerostar 601P, Lycoming IO-540-SIA5, 290 hp each, was priced at $220,900 (1977). The 1978 optional blower in the ventilation system helps to keep the cabin bearable on the ground.

Piper Aircraft adopted the name Sequoya for a production version of what was the Smith Aerostar. The specification of the PA-60 Sequoya 602P is almost identical with that of the Aerostar 601P, but a change of engine variant achieves a greater range at a reduced cruising speed, a better rate of climb on one or two engines, a better service ceiling and improved take-off performance.

 

 

In 1981, Piper introduced the 602P. This airplane is virtually identical to the 601P except for the engines, and they are quite different, even though the horsepower remains the same at 290 a side. The 602P has an engine-turbocharger package that was designed as one unit and offers greater usable horsepower. This can be seen directly in single-engine ceiling: 12,900 feet compared with 9,300 feet for the 601P. Maximum cruise was scaled back a bit from the 601P's original num-ber, to 245 knots. Some of this 11-knot loss can be attributed to a higher maximum takeoff weight, 6,000 pounds as compared with 5,700 pounds for the original, and the rest would go to the drag of the extended wingspan.

To get more from the airplane, Piper installed more horsepower for the 700P. The basic Lycoming 540-cubic-inch-displacement engines run at higher turbo boost, developing the additional 60 hp per side. Lycoming has re-tained the same 1,800-hour recommended TBO. Each engine uses two turbo-chargers. The 700P engines counterrotate, rotate opposite the direction of other twins’; on the 700P, the prop tips rotate away from the top of the fuselage. This came from a retest of the Aerostar design that mandated an improvement in directional control when flying at low airspeeds. The directional control problem was ad-dressed on other models by adding vortex generators, or a supplemental ventral rudder under the tailcone. The 700P also became the first Aerostar produced with cowl flaps and with intercoolers.

The 700Ps cruise number is 261 knots at 81 percent power and 25,000 feet, so, even with the extra power, not a lot of speed is gained over the 601P. Because the 700P uses fuel at 307 pph at 81 percent power, an optional additional 40 USG fuel tank was made available, and most were equipped with it, increasing maximum fuel load to 1,233 pounds, enough for a five-hour flight at relatively high power. With the extra tank, this gave a total of 1,233 pounds (205.5USG). Only 25 or these were built.

 

 

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