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pilots – and you are expected to fly with the same level of professionalism they exhibit.
High altitude or low, it’s vital you fly the airplane precisely. At first you might think the added power of a turboprop means you can get away with a little sloppiness, especially during takeoff and landing. The reality is that even flown precisely, turboprops typically use more runway than piston airplanes. You’ll often have less of a margin for imprecision – you need to be right on speed and glide path to land safely and precisely on speed and attitude for takeoff.
Flight Characteristics
There are several characteristics of most SETPs that cause them to fly differently than the piston airplanes with which you’re more familiar. Let’s look at the variables to get at least a basic idea of the differences:
Wing Loading: Wing loading is the weight carried by its wing area. The higher the wing loading the higher the stall speed. Takeoff and landing speeds increase, and climb speeds decrease as a result. Higher wing loading increases stability and reduces the impact of turbulence, but it often also results in higher stick forces – the airplane “feels” heavy, and it takes more effort to maneuver and to flare for landing. Often, landings in a SETP will be flown with some power instead of the piston-airplane practice of reducing power to idle when you flare. A comparison of the wing loading of familiar piston-powered airplanes, the Cessna 172 and Beech Baron 58, and popular SETPs, the Cessna 208 Caravan, TBM 900 and Pilatus PC-12, tells us that performance and handling will be noticeably different when you transition to turboprop airplanes (see Figure 1).
Power Loading: Power loading is the airplane’s thrust divided by its weight. The higher the power-to-weight ratio, the faster the airplane will accelerate, climb and cruise. Comparing power loading gives you an idea of the differ- ences in performance (see Figure 2).
Weight and center of gravity range: Airplane stability and performance are determined in part by the location of its center of gravity (CG). An airplane with a wide range of allowable CGs will have changes in performance and han- dling depending on how it is loaded. If that allowable range is great even within limits there will be notable differences in the way the airplane flies.
Familiar piston airplanes have fairly narrow CG ranges. The Cessna 172, for example, has a roughly 6-inch range in allowable CGs from the forward to the aft limit. Cirrus’ SR22 has an approximately 4-inch CG range at higher weights. The Beechcraft Baron 58 has a wider CG range, about 7.5 inches. The CG range of the Cessna 208 Caravan, a true freight hauler, is about 22 inches. The TBM 900’s allowable CG range varies by roughly 9.5 inches. Pilatus publishes the CG range of the PC-12 in terms of percent of mean aerody- namic chord (MAC) – the average distance from the leading edge to the trailing edge of the wing. The PC-12’s CG range is from 27 percent to 44 percent of the MAC. Even without converting this to distance in inches, you can visualize a wide variety of performance and handling with variations within the allowable center of gravity envelope. What’s
Figure 1
Figure 2
8 • TWIN & TURBINE / January 2021
SETP Training Resources
Undoubtedly, you’ll be required to attend some insurance- recognized,type-specifictrainingforthetransitionintotheSETP. Most recognized training includes classroom (or computer-based) instruction, simulator training and instructional flight – sometimes a lot of it – in the actual aircraft. There are a number of re- sources, however, that will help prepare you for the proverbial instructional firehose.
One of the best basic overviews is the FAA’s Airplane Flying Handbook, chapter 14. The AFH is available free on the FAA website. Other options include the popular pilot training video sources and no small number of YouTube and similar videos online. But beware the online videos. They may not have been vetted for technical accuracy, or if accurate for one model or serial number string of aircraft may not be applicable to other models or serial number ranges. Don’t forget the Pilot’s Operat- ing Handbook or Aircraft Flight Manual specific to the serial number airplane you’ll fly. Anything you can do to understand the basics and “speak the language” before your formal training begins will help immensely when instruction starts.