EQUIPMENT & MISSION

TPs versus light jets—choice comes down to travel legs and airport use

New turboprops have high performance. But there's a magic factor with a jet that claims the future and charms the buyer.


Aircraft performance comparison
  King Air 350i Avanti II Premier IA Citation CJ2+ Phenom 100 Phenom 300
Range*
(nm)
1,532 1,470 1,105 1,441 1,050 1,920
Avg speed (kts) 284 370 402 360 323 400
Trip fuel (lbs) 2,956 2,800 2,441 2,841 1,987 4,360
Consumption (nm/lb) 0.518 0.525 0.452 0.507 0.528 0.440
Cruise altitude (FL) 350 410 410 450 410 450

* NBAA IFR range + 100 nm alternate + reserve

Comparative aircraft performance. The performance envelopes of turboprops and light jets clearly overlap.

Other significant factors

All of our aircraft feature advanced avionics. Both Beechcrafts, the CJ2+ and the Avanti have the Rockwell Collins Pro Line 21 suite, while the Phenoms have the Garmin Prodigy. Both of these suites provide much lower workload and greatly improved situational awareness compared with systems only a few years older.

The trend will continue. In the past, new technologies were developed for the military and then adapted for the airlines before trickling down slowly to the corporate world and finally general aviation.

Now the flow is completely the opposite, with advances being made in the general and corporate world moving up slowly into the airline world. These advanced technologies mitigate the disparities in the workload between lower and upper altitudes.

Note that the cabin width and height data in the aircraft accommodation comparison table does not tell the entire story.

For example, the King Air has a cross section that is more rectangular than oval or round, providing better headroom when seated. The only way to assess a cabin for suitability is to try it on, preferably on a demo that is representative of one of your typical trips.

In the past, turboprop interior sound levels bordered on painful. I recall a trip in an old Merlin (with no synchro-phasers) that still makes me cringe.

Today, improved technology including aftermarket active noise dampening (similar to that found in ANR headsets) has reduced or even eliminated the distinction. The Avanti cabin, given its engine configuration, is even quieter than a number of jets.

Aircraft accommodation comparison
  King Air 350i Avanti II Premier IA Citation CJ2+ Phenom 100 Phenom 300
Seats
crew*/pax
2/9-11 2/6-8 2/6-7 2/6-7 2/4-5 2/7
Cabin width
(inches)
54 73 66 58 61 61
Cabin height
(inches)
57 69 65 57 59 59
Baggage vol
(cu ft)
71.3 44.1 76.9 65 67 79
Max baggage
weight (lbs)
1,150 300 750 1,000 470 680

* All aircraft are certified for single-pilot operations.

Comparative aircraft accommodation. As with performance, there are overlaps between turboprops and light jets.

It is possible, however, that this interior noise has just been transferred outside. The sound of an Avanti flying overhead is quite distinctive and apparent, in part because the exhaust impinges directly on the propeller.

By the way, the exhaust from a Pratt & Whitney Canada PT6 is quite helpful, providing an additional 30 hp-worth of "free" thrust.
Both turboprops in our group use a version of the PT6—a design that dates back to the sixties.

But these versions bear little resemblance to their great-greatgrandparents. New materials allow internal temperatures that would have destroyed those earlier engines in seconds—and these higher temperatures allow greater efficiencies.

Further efficiency gains have been achieved by improved aerodynamic design and greater manufacturing precision. Of, course, the P&WC jets used on the Phenoms and Williams jets on the Premier and the Citation have also benefited from these improvements. FADECs further reduce the workload and improve efficiency.

Answering the question of whether to turn or to burn

Hawker Beechcraft King Air 350i. The stately King Air has kept pace with the market with its fully up-to-date engines and avionics.

As technology marches on, the distinction between turboprops and jets, already slightly out of focus, will continue to blur. Engine manufacturers have flirted with unducted turbofans and airframers are using geared turbofans (which are really turboprops with a ducted propeller) more often.

Further, turboprops used to be confined to flight levels in the 200s but they are now entering the 400s. In the past, there was a clear demarcation between the missions suited for turboprops and those suited for jets. This is no longer the case and it is probable that, for any given mission, the top 3 suitable aircraft will include both turboprops and jets.

Given the systems sophistication, which reduces pilot workload, and the improved performance of turboprops, there is much less difference today to the flying experience for pilots between turboprops and jets.

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