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Turboprops Review (Part 2)

In the December issue- we reviewed the major in-development and in-production single engine turboprop aircraft models. This month we continue our review of turboprops with a look at some of the contenders in the twin-engine sector.

Dave Higdon   |   1st January 2012
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Dave Higdon Dave Higdon

Dave Higdon writes about aviation from his base in Wichita Kansas. During three decades in...
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Twin Town: Turboprops For Those Who Need More

In the December issue- we reviewed the major in-development and in-production single engine turboprop aircraft models. This month we continue our review of turboprops with a look at some of the contenders in the twin-engine sector.


Deep into the bush or far from dry land out over water- the speed gain of doubling horsepower twin propjets retain their appeal with a segment of the owner/pilot market and- in particular- corporate and charter operators. For some owners some missions beg for nothing less than two powerplants; for others- a second engine adds comfort - and electrical-source redundancy. Indeed- twins often provide payload benefits to the operator too.


All these benefits come at a cost – namely the increased costs of feeding and maintaining two powerplants- hull-insurance premiums and pilot qualifications. No question- they have a place- they have their advantages and fans. But no one in this reporter’s memory ever complained about that second engine once it became the only engine… Following is a review of today’s twinturboprop players.


Hawker Beechcraft Corp: The King Air Series


Come 2013 and 2014 expect Hawker Beechcraft to fete the world with the story of its King Airs - arguably the dominant propjet twin line dating back to its introduction in 1963 and first deliveries in 1964. Indeed- 2013 will represent nearly 50 years of this particular family of airplane… time flies and King Airs have flown through nearly half of the history of flight.


From the original King Air 90 the line has expanded and contracted- and today offers three in-production models. Between them they bridge the markets of the owner/pilot ready for a first turbine with the worlds of big business and demanding military requirements.


Today’s King Air models have all-glass cockpits with the hugely popular Pro Line 21 integrated avionics suite from Rockwell Collins in the three panels (Rockwell Collins reports more than 4-000 installations of Pro Line 21).


The King Airs could serve as a case study in the success of embracing a philosophy of continuous improvement matched by no other airplane line. Here’s a review of the current production models.


King Air C90GTx


Today’s incarnation of the original King Air 90 is the speedy- nimble C90GTx- which owes its existence to the groundwork laid with the original King Air design - one that over time progressively improved to better performance- capability and utility (with three 8-by-10-inch displays in its Pro Line 21 package- as an example).


Today’s C90GTx sports a pair of PT6A- 135 engines making an easy 550 shp. Efficient to a fault- the -135s can power the C90GTx to a top cruise speed of 272 knots- to altitudes as high as FL300- and with utility and flexibility to carry four passengers and crew 1-200 nautical miles – with the available fuel. By filling the fuel tanks more and losing just a little payload- and by relaxing the power setting- more range is possible.


As rugged and reliable for remote operations as it is sophisticated for corporate work- the C90GTx retains the excellent flying characteristics and handling that make it a confident ride for the single pilot facing tough conditions.


King Air 250


Today’s King Air 250 shows what an OEM can do in improving an established performer by revising technologies inside the airplane. Customers of the old Beechcraft King Air 200 offered feedback aplenty on their likes and dislikes- along with the equipment their dream King Air would incorporate- and the manufacturer responded.


The company refined- revised and polished the changes to create today’s King Air 250 – an evolved airplane which reflects those customer opinions.


Thanks to new winglets- new cowl design- new propellers- a thrust-enhancing ram-air recovery system- but the same 850shp PT6A-52 powerplants the King Air 250 needs 16 percent less runway (down to 2-111 feet) and less time to climb to altitude- while also offering a moderate gain in speed: condition dependent- between two and 10 knots.


The runway performance gain opens up about 1-100 more runways to the King Air 250 than were accessible to the King Air 200GT. Fuel efficiency is also up slightly enabling a higher 1-600 miles maximum range.


In addition to all of this- the King Air 250 offers cruise capability up to FL350 – higher than all but a couple of propjets. Deliveries since certification was received in June 2011 have started.


King Air 350i


The crown of the King Air line arguably belongs to the King Air 350i - a big- rugged- fast propjet that retains the rugged reliability and capability of its progenitor- the King Air 90. This is a big airplane boasting a maximum take-off weight of 15-500 pounds – but with speed- distance- space and cost numbers that would turn the head of many of the larger light jet owners. (The MTOW of the 350i is 15-500 lbs. The 350iER has a MTOW of 16-500 lbs.)


Offering a 313-knot maximum cruise speed and maximum-climb rate approaching 2-800fpm the King Air 350i is competitive with many jets on trips of up to two hours. Its ability to use runways under 3-500 feet to get out of- and into an airfield simply enhances the appeal of the King Air 350i.


With full fuel tanks the 350i can still lift more than 1-400 pounds of payload which means you can fill seven of the nine cabin seats and top up with fuel enough for a 1-500 nautical mile business trip – non-stop.


The Extended Range 350iER features additional fuel tanks in the engine nacelles as well as a 1-000 lbs. increase in maximum take-off weight which provides the ability to carry a full fuel five passenger payload across the continental U.S at its lower latitudes – more than 2-200nm.


Piaggio Aero P-180 Avanti II


Nothing else in the realm of propjets delivers performance quite like the Piaggio P-180 Avanti II. That applies to its per-mile operating costs- its range and its velocity – all numbers that are good enough to inspire a little envy in other propjet owners and even a handful of jet operators.


Of course- these stand-out areas only serve to reinforce why the Piaggio P-180 Avanti II embraces its unique configuration – which blends an advanced design with a finely finished cabin- and performance on a par with Italian names like “Ferrari” – the company which owns the design.


The pair of P&WC PT6A-66B powerplants turn five-blade props into 850shp of power- flat rated to ISA+28°C and combine to provide the motive force behind the Avanti II’s remarkable speed and fuel efficiency.


Nothing else with propellers approaches the Avanti II’s 400-plus-knots top cruise speed - although its long range cruise speed of 320 knots places it second in the field. Further- the Avanti II can carry 2-000 pounds in the cabin when at its maximum fuel capacity – and still cover major mileage. The P-180 can take you as high as FL410 which is pure jet territory.


Conversely- no other propjet can cover as much mileage on as little fuel. With a maximum range of 1-450 nautical miles the P-180 Avanti II can consume less than half the fuel of other propjets – and 40 percent less than the closest jets.


Aside from the high-speed abilities of engine and airframe – a ‘smooth-as’ composite aluminum structure – the combination also allows a fully-loaded P-180 to operate with as little as 2-868 feet to clear a 50-foot obstacle; landing takes barely an additional 10 feet.


More information from www.piaggioaero.com




Viking Aircraft : Twin Otter Series 400


For many a happy year workers in Downsview- Ontario assembled some of the world’s most renowned bush and utility airplanes – de Havilland Canada’s Caribou- Buffalo- Beaver- Otter and its twin-engine kin the DHC-6 Twin Otter.


Though de Havilland Canada went away many years ago its legacy lives on in two aircraft – the Dash 8 Q400 regional airlines- made today by Bombardier Aircraft- and the 400-series Twin Otter- made in Western Canada by Viking Aircraft.


This high-wing model enjoyed considerable popularity as a regional airliner in the early 1980s due to its stellar short-field capabilities- its rugged durability and its 19-seat cabin- the most-popular size of that time. Flying on two PT6A-35 engines- the Twin Otter can operate out of short spots- maneuver solidly at anywhere between 80 and 160 knots- and operate with oversize tires- skis- straight and amphibious floats.


More information from www.vikingair.com

Read more about: King Air 90 | King Air C90GTX | King Air 250 | King Air 350i | Piaggio Avanti P-180 II | Viking Aircraft | Twin Otter 400 series

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