Story ID: 030
Citation: Cessna’s Revolutionary Jet
By: David Donald
Caption: Cessna’s original Citation broke new ground for small business jets
Word Count: 1841
Cessna’s Model 500 Citation was a groundbreaker in several senses. It was the first successful entry-level business jet and the first to provide for single-pilot operations. It also brought Cessna—the world’s leading airplane maker in terms of production numbers—into the world of civilian jet aircraft, and the name “Citation” would become synonymous with the company’s top-line offerings through to today’s Ascend, Latitude, and Longitude.
Cessna cut its teeth on jet-powered aircraft in the early 1950s. The company’s Model 318 was one of eight projects bid for a U.S. Air Force competition for a basic jet trainer. Powered by a pair of Continental-Teledyne J69 engines—a license-built version of the French Turbomeca Marboré turbojet that powered the MS.760 Paris light private jet/trainer—the Model 318 was successful and became the T-37 Tweet, of which more than 1,200 had been built by the time production ended in 1975. It also spawned a light attack version, the A-37 Dragonfly, which accounted for another 577 airframes.
In the mid-1950s, Beechcraft—Cessna’s great rival and today’s stablemate within Textron Aviation—had secured a deal with Morane-Saulnier to market the four-place Paris as the first business jet in North America. In response, Cessna schemed a civilian light jet variant of the T-37, which was known internally as the Model 407. It had a fuselage stretched by two feet to accommodate four seats in a pressurized cabin.
Customer interest was poor, and only a wooden mock-up of the Model 407 was completed before the project was terminated. The private/business aviation market was not ready for the concept of a light business jet, and to validate Cessna’s decision, Beechcraft only sold two of the Paris jet and ceased marketing the type in 1961.
For much of the 1960s, the business jet market was dominated by larger aircraft such as the Lockheed JetStar and North American Sabreliner, which were joined by the Dassault Falcon 20 and Grumman Gulfstream II. These high-end products lay outside the traditional markets of either Beechcraft or Cessna, which were both masters of cheaper, smaller aircraft that were aimed more at the general aviation market rather than the very rich, governments, and large corporations.
In 1964, the private/small company marketplace was revolutionized by the arrival of the remarkable Lear Jet 23, and to a lesser extent by the Jet Commander 1121. They were far more affordable to acquire and operate than the larger jets and appealed directly to a wide range of customers.
Beechcraft responded by securing a deal to market the HS.125 and also launched the turboprop-powered King Air. Cessna had no immediate answer to the King Air, and it was not until the mid-1970s that it adopted turboprop propulsion with the Model 441. Instead, it identified a clear gap in the market between the King Air and the Lear Jet, a gap that could be filled by a jet that was faster than the turboprop aircraft, yet cheaper to buy and operate, more versatile, and easier to fly than Lear’s “rocket ship.”
Fanjet 500
In October 1968, Cessna launched its new program, then known as the Fanjet 500. The financial gamble was considerable: various estimates put the cost of the project at between 35 and 50% of Cessna’s net worth. However, with production of piston-engine aircraft drastically dwindling in the early 1970s, the decision to proceed could be said to have ultimately kept the company afloat.
It was an eight-seat aircraft with a cabin and two-place cockpit mounted ahead of the main spar, although it was usually operated with five seats in the cabin. The fuselage design with a flattened oval nose section drew on that of Cessna’s large twin-piston aircraft. A straight wing was adopted to provide ease of flying and to keep approach speeds low, albeit at the penalty of a modest cruise speed of 411 mph compared to the Lear Jet’s 518 mph, a fact that drew sneering comments and derogatory nicknames from its competitors.
With high speed not the principal design driver, Cessna could reduce cost and complexity through features such as leaving the mainwheel doors uncovered after retraction. Moreover, the low approach speed and frugal runway requirements permitted the Model 500 to use many more airfields than its rivals, and it could also operate from semi-prepared strips.
As its name suggested, the most innovative of the Fanjet 500’s new features was its fuel-efficient turbofan powerplant, which was considerably more efficient than the thirsty turbojets of the Lear Jet. The aircraft was the first application for the Pratt & Whitney Canada JT15D, which went on to power several aircraft types, including the Mitsubishi Diamond/Beechjet and Aérospatiale Corvette business jets.
Having first flown in a pod carried by an Avro Canada CF-100 fighter, the JT15D-1 for the Fanjet 500 had a bypass ratio of 3.3 and developed 2,200 pounds of thrust at maximum takeoff power. It had a centrifugal compressor. The initial version employed an outsize fan from the JT9D engine, but later versions such as the JT15D-4 for the Cessna 550 Citation II had a smaller fan and an axial booster component, with a corresponding reduction in bypass ratio to 2.6.
As development continued, the Fanjet 500 received the new name of Citation, after the Triple Crown-winning champion racehorse. The name has stuck throughout the development of Cessna’s jet aircraft family, along with the associated horseshoe logo.
Milt Sills and J.L. LeSueur took the prototype Citation 500—appropriately registered N500CC—aloft for its first flight in Wichita, Kansas, on Sept. 15, 1969. Flight trials uncovered several issues, and development was relatively protracted. Changes made to the design included a lengthening of the forward fuselage and relocation of the engine nacelles. The tailfin was enlarged and more dihedral was added to the tailplanes. Certification was finally granted after two years of flight tests on Sept. 9, 1971.
Citation into Service
With a unit cost of just $695,000, the Citation 500 was an attractive proposition for many customers with limited budgets. Sales were brisk and included high-profile buyers such as golfer Jack Nicklaus, who replaced his JetStar with a Citation in 1976. Initial operators found the Citation not only cheap to operate but pleasant to fly with no surprises. Cessna’s original intentions to make the type no more challenging to handle than its Model 421 piston-twin were achieved.
While Citation sales flooded in, Cessna continued to develop the type. In 1972, a bleed air system to deice the windshield replaced the original electrical system. The first major development was the addition of thrust-reversers as an option in 1974. That year, a new pressurization controller was introduced that permitted operations at up to FL410 instead of the previous authorized limit of FL 350. From late 1975, Collins Pro Line avionics replaced the original RCA system, and in the following year, gross weight was increased by 1,000 pounds to 10,850. At around the same time, longer-span wings were introduced.
These new features were incorporated into the first new variant, the Cessna 500 Citation I, which was introduced in late 1976. It also had improved JT15D-1A engines, offering better performance, while cabin pressure at altitude was increased for greater cabin comfort. A sizeable number of original Citations were re-engined with the JT15D-1A.
Another important development became available in early 1977 in the form of the Model 501 Citation 1/SP, which was certified for single-pilot operation. This further cemented the Citation’s position as the entry-level jet of choice and became particularly popular amongst the growing community of owner-operators.
Cessna had always envisioned the Citation as a single-pilot aircraft, and had designed the original cockpit with most of the system switches on the left-hand side. With an mtow of 11,850 pounds, it was under the 12,500-pound limit for certification in the Normal category. However, the desire to provide Cat II approach capability with only one flight director/autopilot was deemed by the FAA to impose too great a workload on a single pilot, and the Model 500 was certified in the transport category. Substituting the original Bendix FGS-70 with a Sperry SPZ500 flight guidance system satisfied the FAA that the Citation could be certified in the Normal category for single-pilot Cat II operations, and with this system, the Model 501 was born.
Production of the 500 and 501 models came to an end in 1985, with 689 built, and by that time Cessna was committed to follow-on models. The most important of these was the Model 550/551 Citation II, a stretched eight/10-place variant with JT15D-4 engines. This first flew in January 1977, and by the time production ended in 2006, more than 1,000 had been built, including the Citation S/II and Citation Bravo models. Both of these had supercritical airfoil wings, while the Bravo introduced PW530A engines. Further development resulted in the Model 560 Citation V/Ultra/Encore family, stretched from the Citation II.
Another Citation I-derived family emerged in the mid-1970s in the form of the Citation III. This was originally a long-range development of the Model 500 with three JT15D-1 engines but emerged as the Model 650—a larger, T-tailed, swept-wing aircraft powered by a pair of TFE731 engines and with a standing-room cabin. Its Citation VII development became Cessna’s flagship business jet before its position was usurped by the larger Citation X and subsequent Citation-branded models.
Despite carrying the same name, such aircraft can fly much faster, reach a lot farther, and carry far more than the original Citations. Today’s true inheritors of the pioneer’s entry-level DNA are the variants of the six- to 10-seat Model 525 CitationJet family. This was based on the forward fuselage of the Citation II, with straight wings, FJ44 engines, and a T-tail. More than 2,000 have been delivered since the type’s first flight in 1991. The basic Model 525 also provided the basis for a tandem two-seat military jet trainer—the Model 526 CitationJet—which was unsuccessfully bid to replace the long-serving Cessna T-37.
Long-lived Citation
Despite the arrival of newer models, the original Citation continues to be an operational success and a regular sight around the world. Sierra Industries developed a Longwing modification package for early Citations that became popular. It added wingtip extensions that had beneficial effects on range, climb rate, cruise altitude, landing speed, and fuel economy, and added new deicing boots. More than 120 aircraft received the upgrade. Sierra later introduced the Stallion and Eagle II upgrades, which replaced the JT15D engines with better-performing and more efficient Williams FJ44s.
In recent years, the Model 500/501 has remained a popular aircraft, thanks to its ease and cost of operation and its low purchase price. It still plays its part in the used aircraft market, particularly the modernized aircraft. In 2015, a Textron Aviation technical report noted that fleet size numbered 586 aircraft and that they had logged more than five million flight hours. The fleet leader at the time had amassed 25,547 hours: the Model 500/501 has no specified airframe life limitations.