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Quest for Performance: The Evolution of Modern Aircraft


Part I: THE AGE OF PROPELLERS


Chapter 6: Design Maturity, 1945-80


General Aviation Aircraft



[143] The term "general aviation" covers all types of flying except military and commercial airline operations. Only contemporary aircraft designed for business and pleasure are considered here. General aviation aircraft designed for business and pleasure are available in both single-engine and twin-engine models; most models are equipped with horizontally opposed reciprocating engines. However, several high-performance turboprop types are offered. Single-engine types may be had with high- or low-wing location, retractable or fixed landing gear, controllable-pitch or fixed-pitch propeller, and in sizes varying from two place to seven place. The twin-engine aircraft usually employ the lowwing location and have retractable landing gear and controllable-pitch propellers. The twins may be had with or without turbosupercharging, with or without pressurized cabins, and with varying seating capacities. The modern aircraft designed for business or pleasure is almost invariably of all-metal construction, as contrasted with the metal, wood, and fabric construction typical of the pre-World War II general aviation aircraft. Reliability of the internal systems employed in the aircraft and the precision of the radio and navigational equipment have greatly improved as compared with pre-World War II standards. The general aviation aircraft of today are almost universally equipped with an electrical system to power the radios and other types of equipment installed in the aircraft and to operate the self-starter. Hand starting of production aircraft is a thing of the past. The cabins of these aircraft are generally relatively comfortable, are equipped with heaters for wintertime and high-altitude use, and are sometimes equipped with air conditioning for use on the ground and at low altitudes in the summer. The open cockpit is a thing of the past in production aircraft, except for special sport and aerobatic aircraft. Many aircraft employ complete instrumentation and communication equipment for flight under IFR conditions. Most contemporary aircraft employ a tricycle gear that greatly eases the problem of aircraft handling on the ground. The basic aerodynamic configuration of contemporary general aviation aircraft, however, differs little from those in use in 1939.

Contemporary Types, 1970-80

General aviation aircraft are manufactured in a number of different countries; however, the majority of these aircraft are produced in the United States. The major U.S. producers are the Cessna Aircraft Company, the Piper Aircraft Corporation, and the Beech Aircraft Corporation. [144] Each offers a wide variety of aircraft designed for various needs and markets. Six aircraft of different levels of performance, size, and price produced by these manufacturers for different segments of the market are briefly described here.

Two single-engine aircraft representative of the lower performance and price spectrum are shown in figures 6.4 and 6.5. The Piper Cherokee 180 shown in figure 6.4 is an all-metal aircraft with an internally braced, cantilever wing mounted in the low position. The aircraft shown has four seats and is equipped with a 180-horsepower, four-cylinder Lycoming engine of the opposed type. The engine drives a fixed-pitch propeller. The landing gear on the aircraft is fixed, and although not visible in the photograph, the horizontal tall employed on the Cherokee is of the all-moving type equipped with a geared tab. The Cherokee 180 has a maximum speed of 148 miles per hour at sea level and cruises at 141 miles per hour at 7000 feet. The stalling speed with the split flaps deflected is 61 miles per hour. The gross weight of the aircraft is indicated in table III to be 2450 pounds. The Cherokee 180 is representative of one of the lower cost members of a complete family of Piper aircraft that carry the Cherokee name. Some of these aircraft have six or seven seats and more powerful engines that drive controllable-pitch propellers. Other versions of the Cherokee employ a retractable landing gear. The flight of the first production aircraft was made in February 1961, and well over 25 000 Cherokees of all types have now been produced.




Figure 6.4 - Piper Cherokee 180 contemporary general aviation aircraft. [NASA] [Original photo was in color, Chris Gamble, html editor]





[145] Figure 6.5 - Cessna Skyhawk contemporary general aviation aircraft. [mfr]



The Cessna Skyhawk shown in figure 6.5 is one of the lower cost members of an entire series of Cessna aircraft of the same basic configuration. The Skyhawk, like the Cherokee 180, is equipped with a fixed tricycle landing gear and has a four-cylinder, horizontally opposed engine driving a fixed-pitch propeller. Unlike the Cherokee 180, however, the Cessna Skyhawk is a high-wing configuration with a single wing strut on either side of the fuselage to brace the wing. The Skyhawk has a maximum speed of 144 miles per hour and cruises at 138 miles per hour at 8000 feet. The stalling speed with the flaps deflected is 49 miles per hour. The gross weight of the Cessna Skyhawk is 2300 pounds, and the wing loading and power loading are 13.1 pounds per square foot and 15.3 pounds per horsepower, respectively. These values are in the same order as those shown in table III for the Piper Cherokee. The zero-lift drag coefficient of the Skyhawk is 0.0319 as compared with 0.0358 for the Cherokee, and the maximum lift-drag ratios for the two aircraft are 11.6 and 10.0, respectively.

Two representative high-performance single-engine general aviation aircraft are shown in figures 6.6 and 6.7. The Beech Bonanza V-35B shown in figure 6.6 is of all-metal construction, has an internally braced wing mounted in the low position, has single-slotted flaps, and is equipped with a fully retractable tricycle landing gear. The aircraft is equipped with a six-cylinder, horizontally opposed Continental engine of 285 horsepower that drives a controllable-pitch propeller. The aircraft...




[146] Figure 6 6 - Beech Bonanza V-35B contemporary general aviation aircraft. [mfr]



...can be configured for four, five, or six seats. Data for the Bonanza are given in table III. The unique Butterfly tail combines the stability and control functions of both the conventional vertical and horizontal tails. The gross weight of the aircraft is 3400 pounds. The aircraft has a maximum speed of 210 miles per hour at sea level, cruises at 203 miles per hour at 6500 feet, and has a stalling speed of 63 miles per hour. The zero-lift drag coefficient is a very low 0.0192, and the corresponding maximum lift-drag ratio is 13.8. The prototype of the Bonanza first flew in December 1945, and the aircraft has been continuously in production since 1947. Approximately 10 000 Beech Bonanzas have been built.

The Cessna Cardinal RG II shown in figure 6.7 is a high-performance aircraft with an internally braced wing mounted in the high position. The aircraft is equipped with a fully retractable tricycle landing gear and is equipped with a four-cylinder, horizontally opposed, Lycoming engine of 200 horsepower that drives a controllable-pitch propeller. The Cardinal is of all-metal construction and is equipped with trailing-edge flaps and an all-moving horizontal tail employing a geared trim tab. The aircraft has a maximum speed of 180 miles per hour at sea level, cruises at 171 miles per hour at 7000 feet, and has a stalling speed of 57 miles per hour. The aircraft weighs 2800 pounds. The...




[147] Figure 6 7 - Cessna Cardinal RG II contemporary general aviation aircraft. [mfr]

...zero-lift drag coefficient of the Cardinal is 0.0223, and the corresponding maximum lift-drag ratio is 14.2.

The first twin-engine aircraft designed specifically for business use was probably the Beech Model D-18, first produced in 1937. This aircraft was similar to the Douglas DC-3 in general appearance, although much smaller, and was in continuous production from 1937 until the early 1970's. A wide variety of twin-engine aircraft of various sizes and with different levels of performance are now offered for business use. Two contemporary twin-engine aircraft are shown in figures 6.8 and 6.9.

The Cessna 310 shown in figure 6.8 is representative of one of the smaller contemporary twin-engine aircraft offered for business use. The aircraft is a low-wing configuration with an engine mounted in each wing on either side of the fuselage. The aircraft can be had with both normally aspirated engines or with turbosuperchargers. The specifications and performance given in table III are for the aircraft without turbosupercharging. The engines are six-cylinder, horizontally opposed, Continental engines of 285 horsepower each that drive controllable-pitch, full-feathering propellers. The aircraft normally has a seating capacity of five but can be configured for six. Maximum speed is 238 miles per hour at sea level, and cruising speed is 223 miles per hour at 7500 feet. The wings are equipped with split flaps which with a wing loading of 30.7 pounds per square foot result in a stalling speed of 77 miles per hour. The gross weight of the aircraft is 5500 pounds. The...




[148] Figure 6 8 - Cessna 310 contemporary twin-engine general aviation aircraft. [mfr]



...Cessna 310 has a zero-lift drag coefficient of 0.0267 and a maximum lift-drag ratio of 13. The Cessna 310 was first flown in January 1953 and has been in continuous production ever since. The aircraft is unpressurized and may be thought of as the smallest of a whole line of Cessna twins, both pressurized and unpressurized.

The Beech Super King Air 200 shown in figure 6.9 is an example of a new, relatively large, high-performance twin-engine business aircraft. Provision is provided for 2 pilots and 6 to 13 passengers, depending on the configuration. The cabin is pressurized to permit comfortable cruising flight at high altitudes. Power is provided by two Pratt & Whitney PT6A-41 turboprop engines of 850 shaft horsepower each. The engines drive controllable-pitch, full-feathering, reversible propellers. The low-wing configuration of the aircraft is conventional although the use of a T-tail on a straight-wing propeller-driven aircraft is somewhat unusual. The use of this tail arrangement is said to reduce both vibration resulting from the slipstream of the engines and trim changes with flap deflection. The aspect ratio of the wing is 9.8, which must be considered as relatively high for any aircraft. The King Air 200 has a maximum speed of 333 miles per hour at 15 000 feet and a maximum cruising speed of 320 miles per hour at 25 000 feet. The aircraft is equipped with single-slotted flaps that together with a wing loading...




[149] Figure 6.9 - Beech Super King Air 200 contemporary twin-engine turboprop general aviation aircraft. [mfr]



....of 41.3 pounds per square foot give a stalling speed of 92 miles per hour. The gross weight of the aircraft is 12 500 pounds. The Beech Super King Air 200 was certified in December 1973 and is now in series production.

Other Types of General Aviation Aircraft

The six aircraft just described may be considered as representative of generic classes of aircraft designed for business and pleasure use. In order to gain a true appreciation of the wide variety of such aircraft offered today, the reader is referred to the current year's issue of Jane's All The World's Aircraft. Other types of aircraft of interest and not described here are specially designed agricultural aircraft intended for spraying and dusting crops. These aircraft will also be found in Jane's, as will many types of sport and aerobatic aircraft. Another segment of general aviation aircraft is made up of the so-called home builts. These aircraft, which are built by individuals or clubs at home, are gaining in popularity and are flown in relatively large numbers in this country. They are usually not certified under any of the pertinent federal air regulations but, rather, operate in an experimental category. Many of the more popular types of home-built designs are also described in Jane's All The World's Aircraft.