Thursday, June 19, 2008
A Trainer With Attitude
The Diamond DA20 brings fun and enthusiasm to flight training
|As of two years ago, the training market became a little more complex with the official introduction of a dozen or more light-sport aircraft. Today, the number of different LSA models has swollen to well over 60, and that figure increases on practically a daily basis. Many of these airplanes are fine little two-seaters, easily capable of handling the training mission despite their occasional performance limitations, and that’s exactly the market their manufacturers are targeting.|
|The Eclipse features an aft-hinged hatch that folds up and to the rear, allowing a pilot and copilot to climb aboard from both sides. Joysticks are in the front center of each seat, falling readily to hand, and all of the trainer’s circuit breakers are in clear view.|
Despite what might appear to be an almost delicate structure, the DA20 is actually unusually strong and durable. Diamond has certified the airplane to the more rigorous demands of the utility class. That means G-limits are 4.4 rather than the normal category’s 3.8.
Similarly, the DA20 is approved for spins, one reason the U.S. Air Force has selected the Eclipse as its trainer for the Air Education Training Command in Colorado Springs, Colo. (The Air Force uses the DA20 for its 40-day, 25-hour Initial Flight Screening of up to 1,700 pilot candidates yearly. The training fleet will total 45 airplanes when deliveries are complete.)
Takeoff with each horsepower lifting 14 pounds of airplane is a fairly leisurely process, but the Eclipse still manages to lift off in 1,300 feet and transition into a surprisingly aggressive climb, a characteristic the USAF found especially attractive in Colorado’s frequent high density altitude conditions.
Despite (or perhaps because of) its advantages in primary flight training, the Eclipse has an attraction outside the training arena, and in that respect, climb and cruise numbers score well. Flight schools don’t care much about climb and cruise in a trainer, as there’s little need to vault a few thousand feet up to altitude only to race 10 miles out to the practice area. Conversely, private owners care a great deal about their airplanes’ vertical and horizontal speed, especially in this day of continuously rising fuel prices in which the equation of time, fuel and distance has a significant impact on deflating an owner’s wallet.
To that end, the DA20 offers a combination of performance uncommon for an airplane in this class. Climb is listed as 1,000 fpm, and that’s certainly not a function of the power or wing loading, neither of which is that impressive. It very well may be related to the airplane’s European Wortmann FX 63 airfoil section, a combination of short chord and long span that results in an aspect ratio of 10.2. (Aspect ratio is the proportion between a wing’s span and average chord. All other things being equal—which almost never happens—the higher the aspect ratio, the more efficient the wing.)
In contrast, a Bonanza scores 6.2 and a Warrior 7.2. Drawing on their days of building superefficient sailplanes with high lift-to-drag ratios, all Diamond’s airplanes feature high aspect ratios. The DA20 offers the best aspect ratio of any trainer.
|Powered by a 125 hp Continental IO-240 engine, the Eclipse trainer climbs at 1,000 fpm and cruises at well over 130 knots. With the 24-gallon tank full, you can cover almost 400 miles in three hours on just 18 gallons.|
It may also offer the best mileage of any production piston airplane in the sky, at least of any that burn avgas. Like the other Diamonds, the Eclipse is a slippery composite design, with very little left hanging out to grab the wind. There are no rivet heads, butt joints or any other protrusions to pull down the speed, just an incredibly smooth composite wing and fuselage surface to facilitate the passage of air.
The small, 240-cubic-inch Continental engine puts out only 125 hp, and cruise speed is still well over 130 knots. Even at 6 gph, that works out to nearly 22 nm per gallon, or 25 seat miles per gallon in automotive parlance. In other words, with the single, fuselage-mounted, 24-gallon tank full, you could expect to cover nearly 400 miles in three hours on only about 18 gallons. I can’t think of another airplane that could come close to that number, much less any car at the same speed. Even if you could talk the California Highway Patrol into closing off Interstate 5 between L.A. and Sacramento, you’d be hard pressed to duplicate that time in a Ferrari, and you’d probably burn at least twice the fuel.
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