Cessna caravan i plight analysis

Vocabulary: avionics_, de-icing, plywood, bulkhead, cargo net, canvas divider, load shift, type-rating, boot, twin-sparred, strut, average, slab, spoiler, adverse yaw, to handle, ground clearance, propeller clearance, blade, to deflate, ambient, inlet, lever, evaluation, column force, to pitch nose-down, to pitch-up.

Exercises:

I. Read the text. Pay attention to the description of the systems of plane control.

II. Answer the questions:

1.Is the described aircraft a passenger one or has it a military application?

2. What equipment is it provided with?

3. Is it possible to use the Caravan I for cargo carrying?

4. What are the peculiarities of the wing structure?

5. What is the engine operation characterized by?

6. What are the handling characteristics of the plane?

7. When does the nose-down reaction occur?

III. Determine the theme of each paragraph.

IV. Write down the theme of each paragraph to get the logical plan of the text.

V. Think about the plan and combine it in a logical order.

VI. Make a summary.

It is the third production Model of the series of utility aircraft, 208 Caravan I, and contains optional avionics and equipment, including full de-icing, oxygen and a refueling ladder¹ stowed in the back.

208A a special version – will have no windows aft of the flight deck, and a three-compartment glass-composite cargo pod attached under the fuselage. The floor will be reinforced with plywood panels and the rear bulkhead will be replaced by a rollup canvas divider. Cargo nets are fitted and steel panels will protect the pilots in case the load shifts. The 208A have a full set of King avionics, including an autopilot and a weather radar with its antenna unit mounted in the right wing. Plight instruments are provided for a co-pilot. Because the aircraft weighs less than 5,670kg, pilots do not need a type rating, but Cessna offers training as part of the sale.

The two-piece over-under cargo door, measuring 124.5 cm x 127 cm was designed for Federal Express and Cessna will now develop a door which can be opened in flight, or left open or removed before flight to permit air drops of parachutists or cargo.

Though based on the NACA 23000 aerofoil, the Caravan I wing is tapered in chord and thickness and carries powerful slotted flaps. Though twin-sparred, each wing is only supported by a single strut at the forward spar and this is large enough to justify a boot when de-icing is fitted. At 128kg/m², the wing loading is average for the gross weight, but the power loading, at 5.5 kg/SHP would be rather high for a short-field aeroplane if the wing were a plain NACA 23000 slab. Wing thickness tapers from 17 per cent at the root to 12 per cent at the tip and the aspect ratio is 9,5 : 1. The use of slot-lip spoilers² to assist the ailerons makes it possible to occupy much more of the trailing-edge with flap and probably reduces adverse yaw, which normally be-devils³ the handling of high-wing aeroplanes.

Cessna adopted a nosewheel landing gear because more pilots are familiar with it, for passenger comfort on the ground and to have a level cargo floor. Consequent disadvantages are reduced ground clearance for the 254cm-diameter, three-blade propeller and complications when operating on skis, which Cessna is also developing. Propeller clearance is at least 17.15cm with the standard nosewheel tyre deflated and the strut compressed, but there has been one propeller ground strike.

The Pratt & Whitney Canada PT6A-114 engine, flat-rated at 600 SHP in ambient temperatures up to 58°C, is canted down five degrees and offset to the right to minimize torque effects, and this also improves forward vision in the climb. The engine inlet, located on the left side of the nose, passes air through a particle separator which is controlled by a cable and lever inside cockpit.

Engine operation during the evaluation flight was relatively smooth and response was quick. Because the engine is flat-rated, both temperature and torque limits have to be observed but, on this day, temperatures stayed well within the normal range. Maximum propeller rev/min⁴ are 1,900 but, in cruise, they are set at about 1,750. The torque limit of 1,685 lb/in² ⁵ tended to be reached rather quickly and, above 1,500 lb/in, the needle almost jumped to, or past the limit, making over-torquing a ready possibility. Below 10,000 ft, limiting torque was reached with the power lever only half way through its travel.

Approaches were flown at 1,000 lb/in² torque until the start of descent, where 600 lb/in² was used at all flap settings, giving a steady 500 to 600 ft/min descent rate. Throughout the evaluation flight, fuel consumption stayed 10 to 20 lb/h below book values, and indicated speeds, on a 10°C day with barometer setting of 29.84in Hg, were two to four knots⁶ below book⁷. Others doing similar demonstrations reported slightly higher-than-book speeds and fuel consumption figures.

The Caravan I is one of the bigger 7.3001b (3,300kg) aero-planes. But it felt stable in roll, handled well generally, offered good visibility over the nose and sideways ahead of the wing and, for the most part, felt like a somewhat lighter aircraft, even at or near maximum gross weight.

From a handling standpoint, the aircraft required no unusual I column forces except when extending flaps or applying power rapidly when trimmed hands-off in level flight. The plane had a tendency to pitch nose-down with addition of flaps, but during the flight, adding flaps in level flight brought a rapid pitch-up and substantial forward force on the control yoke was necessary to regain straight and level flight. The nose-down reaction probably occurs when the engine is at low power. The need for strong nose-down control probably accounts for the vortex generators on top of the elevators.

The aircraft is designed for long overhaul life, and for operation by relatively inexperienced pilots. In that sense, it may be a success, but its market is filled with older airplanes, more or less designed for the same job.

4100 знаков

Notes:

1. refuelling ladder – топливозаправочный шланг

2. slot-lip-spoiler – щелевой интерцептор консоли

3. to be-devil – (зд.) ухудшать

4. rev/min (revolutions per minute) – об/мин

5. lb/in (pounds per square inch ) – фунт/кв. дюйм

6. kn (knot) – (морской) узел – 0,514444 м/сек.

7. below book – (зд.) ниже нормы

Учебное издание

О.Б. Салманова, А. Г. Лещенко

АННОТИРОВАНИЕ И РЕФЕРИРОВАНИЕ ТЕКСТОВ ПО АВИАЦИОННОЙ ТЕМАТИКЕ. (АНГЛИЙСКИЙ ЯЗЫК):