v1.0.0 / 01 may 09 / greg goebel / public domain
* In the 1980s, the Cessna Corporation of the USA began work on a single-engine turboprop utility aircraft, which would emerge as the Cessna 208 "Caravan". It proved extremely popular, with Caravans sold to customers all over the globe. Recognizing the success of the Caravan, in the next decade the Pilatus Company of Switzerland came up with a competing turboprop utility single, the "PC-12", which has also proven popular. This document provides a history and description of the Caravan and PC-12.
* In 1981, Cessna began work on a next-generation "bushplane", designed for hauling passengers and cargo under austere conditions. The design that emerged, the Cessna "Model 208 Caravan", was a single-engine turboprop machine with a high wing, fixed tricycle landing gear, a boxy fuselage that could accommodate three-abreast seating, and a large cargo door.
The first Model 208 prototype performed its initial flight on 9 December 1982. The first production Caravan was rolled out in August 1984. It was powered by a single Pratt & Whitney Canada (PWC) PT6A-114 turboprop engine providing 448 kW (600 SHP) and driving a McCauley three-bladed reversible propeller.
All flight surfaces were straight, with the tail featuring a large leading-edge fillet. The wings featured twin spars, a single bracing strut on each side of the aircraft, and a dihedral of 3 degrees. Flight controls were conventional and mechanically actuated, except for electrically actuated flaps. All landing gear assemblies had single large wheels, with disk brakes on the main wheels; it is unclear if the nosewheel was steerable or ground maneuvering was by differential braking. An amphibian version was available, featuring floats with optional retractable landing gear -- additional "finlets" was placed on tailplane of the floatplane to ensure yaw stability. Ski landing gear was also available.
The Model 208 featured a basic avionics suite. An optional Bendix/King
RDS-82 weather radar could be fitted in a pod on the leading edge of the
right wing. De-icing gear was also optional, tropical operators having
little need for it, with the de-icing kit including pneumatic de-icing boots
for the flight surfaces and electrical de-icing for the windscreen. Up to
ten passengers or 1,360 kilograms (3,000 pounds) of freight could be carried.
Heating was standard, air conditioning optional; the cabin was unpressurized,
with an oxygen system optional. There were cockpit doors on each side; a
horizontally-split (open up / down) cargo door on the left rear fuselage; and
a fold-down "airstair" door on the right rear fuselage.
CESSNA MODEL 208 CARAVAN:
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spec metric english
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wingspan 15.88 meters 52 feet 1 inch
wing area 25.96 sq_meters 279.4 sq_feet
length 11.46 meters 37 feet 7 inches
height 4.32 meters 14 feet 2 inches
empty weight 1,724 kilograms 3,800 pounds
MTO weight 3,310 kilograms 7,300 pounds
max speed at altitude 325 KPH 200 MPH / 175 KT
service ceiling 8,410 meters 27,600 feet
takeoff run 300 meters 1,000 feet
range 1,800 kilometers 1,115 MI / 970 NMI
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* Sales of the initial Model 208 were modest at first, until Federal Express
entered into discussions with Cessna to build a Caravan variant optimized for
the parcel business. The result was the "Model 208A Cargomaster", which was
a pure cargolifter, with the passenger windows and left rear door deleted,
plus a large cargo pannier fitted to the belly. It also featured an increase
in tail height by 15 centimeters (6 inches), longer engine exhausts to keep
hot exhaust gases off the pannier, and Bendix-King avionics. FedEx ordered
177 Cargomasters and the Caravan series took off.
* FedEx liked the Cargomaster so much that the company then ordered a derivative with higher load capacity, the "Model 208B Super Cargomaster", which featured a 1.22 meter (4 foot) fuselage stretch, using plugs fore and aft of the wing, and a more powerful PT6A-114A turboprop engine with 503 kW (675 SHP). Load was increased to 1,590 kilograms (3,500 pounds). Initial flight of the first Super Cargomaster was on 3 March 1986, with deliveries later in that same year.
The Super Cargomaster led in turn to a similarly stretched version of the Caravan, the "Model 208B Grand Caravan", with windows and a quick-change cabin capable of carrying 14 passengers or freight. The pannier was optional.
In 1998, the original Model 208A was relaunched with the PT6A-114A engine as the "Caravan 675", with the "675" of course standing for the engine horsepower. Over 1,700 Caravans were sold to 2007, and the Caravan family continues to be enhanced, with a Garmin G1000 glass cockpit fitted in production from 2008. Cessna also offers various upgrade packages to modernize older Caravans.
* In 1986, Cessna began to promote a militarized version, the "U-27A", intended primarily for troop and cargo transport, paradropping, and medevac missions. It had an increased electrical power supply to support avionics for other missions such as electronic surveillance and maritime patrol. A "Low Intensity Conflict Aircraft" version was also proposed, featuring one centerline and six underwing pylons to carry offensive stores, and there was consideration of its use for counterinsurgency operations in South America.
Nothing came of that effort early on. However, in 2009 the Iraqi Air Force (IqAF) obtained five armed Cessna Grand Caravan 208Bs for the counter-insurgency role. These "Combat Caravans" featured an electro-optic / infrared (EO/IR) turret on the belly and a stores pylon on each wing, the usual store being a Hellfire missile; small laser-guided bombs and 70 millimeter rockets are also plausible stores.
The combat systems were leveraged from the Predator unmanned aerial vehicle (UAV). The turret was offset to the left while the engine exhaust was shunted to the right to avoid thermal interference. The Combat Caravans featured weather radar, and the aircraft were fitted with a defensive countermeasures system. The combat modifications were performed by ATK Integrated Systems in Forth Worth, with Iraqi pilots trained in Texas as well. The IqAF also operates Caravans in the training, transport, and surveillance roles.
The US Army now seems to be very interested in the Caravan for "dirty little wars" and has been experimenting with an "optionally piloted" Caravan 208B UAV under the "Caravan Optionally Piloted Aircraft (COPA)" project. COPA Caravans would be used for high-risk missions; details remain mostly secret for the time being.
* The success of the Caravan did not escape the notice of competitors. In 1989, Pilatus of Switzerland launched the "PC-12" program, focusing on a turboprop single for executive transport and light cargo carriage roles. Initial flight of the prototype was on 31 May 1991. Trials going well, certification was obtained in 1994, with deliveries before the end of the year. While the Caravan has a certain utilitarian clean good looks -- a freight-hauler that can be used as an executive transport -- the PC-12 is sleeker -- an executive transport that can be used as a freight-hauler. The PC-12 is somewhat heavier than the Caravan and has distinctly higher performance.
The PC-12 has a low wing with winglets, a tee tail with a dorsal fillet, and
tricycle landing gear -- hydraulically activated, all single wheels, the
steerable nose gear retracting back, the main gear retracting in from the
wings. The PC-12 was originally powered by a PWC PT6A-67B turboprop,
providing 1,200 kW (1,605 SHP) and driving a four-bladed Hartzell propeller.
The PC-12 is mostly made of aircraft metal but has some composite parts, such
as the winglets. The flight surfaces are pneumatically de-iced, while the
windscreen and prop are electrically de-iced.
PILATUS PC-12:
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spec metric english
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wingspan 16.08 meters 52 feet 9 inch
wing area 25.8 sq_meters 277.8 sq_feet
length 14.38 meters 47 feet 2 inches
height 4.26 meters 14 feet
empty weight 2,386 kilograms 5,260 pounds
MTO weight 4,000 kilograms 8,820 pounds
max speed at altitude 500 KPH 310 MPH / 270 KT
service ceiling 10,670 meters 35,000 feet
takeoff run 310 meters 1,020 feet
range 3,310 kilometers 2,060 MI / 1,790 NMI
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An optional Honeywell weather radar pod can be fitted on the right wingtip.
The aircraft has a fold-down airstair door on the left side of the fuselage,
with a large upward-opening cargo door at the rear on the same side; there is
an emergency exit above the wing on the right side. The PC-12 features a
reinforced floor for cargo hauling. Flight crew is one or two. Various
configuration options were offered:
* A variant of the PC-12 with gross weight increased from 4,000 to 4,500 kilograms (8,820 to 9,920 pounds) was certified in 1996 and became production standard in 1997, with this version known as the "PC-12/45". Another improved variant with gross weight increased to 4,740 kilograms (10,450 pounds) was introduced in 2006, with the designation of "PC-12/47". The PC-12/47 could either handle 240 kilograms (530 pounds) more payload or extend its range by 650 kilometers (400 miles / 350 NMI).
By mid-2006, over 600 PC-12s of all types had been sold. The latest version of the PC-12 is the "PC-12 Next Generation (NG)", which features a redesigned cockpit with a Honeywell Primus Apex avionics system built around four color flat-panel displays, plus an uprated PWC PT6A-67P turboprop engine with 895 kW (1,200 SHP). The PC-12 NG was announced in 2006, with initial deliveries in 2008. Upgrade packages are available to modernize older PC-12s to glass cockpits as well.
* The PC-12 has been obtained by military and paramilitary services as a utility aircraft, one of the best-known users being the US Air Force, which operates the type as the "U-28A". It appears to have a militarized communications suite but no other optimizations for Air Force service.
However, in 1995 Pilatus announced a "multi-mission" variant of the PC-12 for surveillance, environmental survey, aerial mapping, and so on. This variant was originally named "PC-12 Eagle" but later became known as the "PC-12M". The PC-12M features an uprated electrical power generation system to support sensor or other payloads, plus a quick-change interior to permit flexible mission support.
The initial PC-12M demonstrator flown in 1995 featured a Raytheon Sea Vue synthetic aperture radar (SAR) in a centerline belly pod with an electro-optic / infrared (EO/IR) turret at the front of the pod, plus a digital datalink system. Two more demonstrators were flown, with one ending up being used by the Swiss for trials. There was little interest in the concept in the 1990s and the PC-12M effort got the axe in 2002.
It was promptly revived in 2003 in a new configuration as the "PC-12 Spectre", which in development features a retractable EO/IR turret under the rear fuselage and twin workstations, plus a digital video recorder and a military communications / datalink system. Of course the Spectre is now being offered with PC-12 NG flight systems; other gear, such as a SAR or defensive countermeasures, can be added at customer request. The Spectre has proven more successful than the Eagle, with ten delivered by 2006; users include Switzerland, Argentina, Bulgaria, and the US Department of Homeland Security (USDHS). The USDHS has at least three, being used for border patrol.
* Sources include:
A number of editions of JANE'S ALL THE WORLD'S AIRCRAFT, plus the Cessna and Pilatus websites, were also consulted.
* Revision history:
v1.0.0 / 01 may 09 / gvg
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