Update-Cessna Citation Jet

Launched at the 1989 National Business Aviation Association Convention, the new CitationJet design was initiated during the late 1980s as a replacement and successor for the highly successful though out of production Model 500 Citation and Citation I, of which a total of nearly 700 of both models had been delivered.
Developed as an entry level business jet with accommodation for a maximum offive (six if there is one pilot) passengers, the CitationJet is the smallest of a family of small to medium sized business aircraft, ranging from Citation II to the high speed, long ranging Citation X which is currently under development.

As a replacement for the Citation 500 and the Citation I, the CitationJet offers substantially enhanced performance and operating economics.
Cessna promises that the CitationJet will posses comparable short field performance, longer range and higher speeds while consuming less fuel and affording better maintainability and reliability.
For example the CitationJet will travel at 30kt (56kph)faster, with 10%further range than the Citation I.

One of the major sales aims is to capture a large percentage of twin engined turboprop business aircraft market dominated the King Air, Conquest and Cheyenne.
While the CitationJet is smaller than these aircraft it will use the same or less fuel than an up-market turboprop, particularly over stage lengths further than 200nm (371km), while cruising at a very substantial 70 to 100kt (130 to 185kph)faster but offering comparable operational flexibility.
It is worth noting however that turboprops generally have longer range and better field performance.

The CitationJet design was kept simple by using a limited degree of commonality with the Citation II and V and by using uncomplicated systems,fewer components,simple tooling and low cost production techniques wherever possible.
The nose, cockpit, and fuselage section are the same as those of the Citation II and V, which helps reduce production and design costs.
Another example of the simplicity of the CitationJet’s design is the use of thrust attenuation in place of thrust reversers.
Used for braking and reducing thrust, paddles behind the engines can be deployed into the exhaust stream to reduce forward thrust.

Simplicity of design also extends to the engines, WilliamsRolls FJ44 turbofans.
Williams International, who has extensive experience constructing small, low weight jet engines for cruise missiles, is partnered in the FJ44 programme by Rolls Royce which has had a significant role in development, adding its considerable experience in producing long life commercial turbofans.

Development of the FJ44 began in 1980 as a modern technology turbofan for small business aircraft with low purchase, maintenance and operating costs and high reliability and fuel efficiency.
Along with the CitationJet, the FJ44 has also been selected for use by its main competitor, the Swearingen SJ30.
The twin spool, medium bypass turbofans, with a bypass ratio of 3.
3:1, are rated at approximately 1,9001b thrust.
With a dry weight of just 204kg (450lb) the FJ44 compares very favorably with the Pratt & Whitney engines of the earlier Citation I as it is 31kg (691b) lighter and has 16% lower specific fuel consumption.
Of modular design, the entire hot section consisting of transition duct, combustor and turbines can be removed from the engine for inspection without the engine having to be removed from the airframe.

The key to reduced weight, improved simplicity and easy maintainability was the use of just 700 components in the FJ44, compared to approximately 2,500 parts in equivalent jet engines.
This has been achieved by using single piece rotors and stators, in place of individual blades assembled in slots while the compressors were machined from titanium.

An exception to the rule of keeping the design simple is the wing, which features a carry through structure design and Natural Laminar Flow.

The laminar flow wing is aimed at reducing drag, which gives an extra 10 to 15kt (19 to 28kph) cruise speed with the same available thrust.
Cessna is aiming to have the air flowing over the wing laminar for between 30 and 35% of the chord, meaning that the air flowing over the wing will not become turbulent and drag inducing until further down the wing than is usual.
To achieve laminar flow the wing must be kept as smooth as possible to reduce skin friction drag.
Increased skin thickness of the wing, which eliminates buckling and dimpling ofthe wing’s skin, keeps drag to a minimum and the airflow laminar for longer.
However, performance figures for the CitationJet do not include the effects of laminar flow because the smooth surface of the wing can be dramatically affected by rain, ice and foreign particles.
An explanatory feature on laminar flow appeared on p49 of our April ’92 issue.

The carry through wing structure passes under the fuselage ensuring that the inside cabin is unobstructed, keeping the internal volume available to a maximum and further enhancing customer appeal. Cabin width is 1. 49m, with a height of 1. 46m; while the length between the pressure bulkheads is 4. 84m. The cabin features between four and five seats and a small lavatory, while there is a tail baggage compartment.

First flight of the CitationJet occurred on April 29, 1990, the prototype has since been joined by a preproduction aircraft in flight testing.
FA A certification is due late this year, while first deliveries will be during early 1993.
With superior performance figures when compared with twin engined turboprops and the older Citation I, Cessna confidently predicts that over the coming fifteen years it will sell 1,000 CitationJets.

Disregarding cabin space as a consideration, there are few reasons now to purchase a turboprop as a corporate aircraft over the CitationJet.
With higher cruising speeds and similar fuel burn and ownership costs, the Cessna becomes a very attractive option.
Although facing stiff competition from the more expensive,more complex,faster and longer ranging SJ30, the Citation Jet’s success seems assured.