World’s Best Trainer

Along comes Oshkosh AirVenture 2010, and one of my assignments was to fly the newest version of Diamond's DA20-C1 Eclipse. I had flown the DA20 several times before, and I was well aware of what a fun machine it was. It had been two years since my last visit, and I was immediately taken with the airplane's remarkable adaptation to the training role. I couldn't help speculating what a wonderful airplane this would make for Peggy, or any other student pilot looking for a trainer, that's as much fun as it is instructive.

If you're looking for a true two-seat, teaching machine these days, and you'd prefer to stay with a new, certified aircraft, there are only three real candidates. In Peggy's case, her experience with the Archer and Skyhawk proved they could be adapted to flight training, but we always knew they were too much airplane for the mission. If you rent a four-seater, you pay for the privilege of hauling those four seats through the sky, regardless of whether they're all occupied.

The only certified 2-seat machines that could be construed as dedicated trainers are the American Champion 7EC Champ, the aforementioned Diamond DA-20 C1 and the Liberty XL2. The Champ came first and has been around for decades, but the trend has been away from tailwheels in favor of nosedraggers. The moral is that the early bird very well may get the worm, but the second mouse gets the cheese. (Yes, I'm aware there's a long list of capable LSAs coming on the market for flight training at reasonable rental prices, but these aren't yet readily available in most parts of the country.) The Liberty XL2 is the most recent addition to the class, premiering in 2005 and employing a FADEC version of the same engine installed in the Eclipse. By the end of 2009, Liberty had sold about 120 airplanes, so there's no question they'll be a factor in the training market for the foreseeable future.

At Oshkosh, I flew the C1 with Diamond demo pilot and instructor Rob Johnson, an old friend from several other flight evaluations and a confirmed C1 lover. Johnson is more than just a demo pilot, however. He actually purchased an Eclipse and uses it to instruct in and around London, Ontario, Canada, where the C1s are built. His knowledge of the Eclipse extends from the production line to the sky, and I can't imagine a better check pilot on Diamond products.

The C1 Eclipse (Diamond had the model name on a real airplane long before the better-known VLJ) has been around since 1998, and it has consistently endeared itself to a decade of pilots. The type was introduced as a follow-on to the 81 hp Rotax 912-powered Katana. The C1 was offered with a Continental IO-240 engine rated for 125 hp.

TBO on the Rotax 912 was initially 1,200 hours, fairly low by aircraft standards, but the recommended overhaul interval has since been increased to 1,500-2,000 hours, depending on serial number. A few advantages of the Rotax included slightly better specific fuel consumption and lower installed engine weight than most alternative powerplants. The Rotax 912 was 70 pounds lighter than the Continental that replaced it. This translated directly to better payload. Another benefit was the Rotax cooling system, water cooling for the cylinder heads and conventional air cooling for the cylinders themselves. Hot weather usually wasn't a problem for the Rotax.

Conversely, the Continental IO-240 offered 55% more power, and that allowed Diamond to increase the airplane's gross weight by 150 pounds, to 1,764 pounds. The result was a gain in payload, especially significant for a two-seater and a major advantage for the C1.

To further accommodate the heavier weight and maintain a reasonable CG, Diamond moved the battery off the firewall to behind the baggage compartment. The wing sweep also was modified, from one degree aft to about .5 degrees to help shift the center of lift farther forward. The Rotax-powered airplanes included simple, hinged flaps, but the heavier model demanded more sophisticated slotted flaps to reduce stall speed to the JAR/VLA-specified maximum of 45 knots. As a result, the current C1 Eclipse offers a dirty stall of 42 knots.

Like all other Diamond products, the Eclipse is a composite design, intended to help minimize drag, reduce weight and curtail maintenance. The carbon-fiber-reinforced plastic offers an otter-sleek, uninterrupted surface with no rivets or section lines. This presents less drag to the relative wind and helps maximize the airplane's drag coefficient. In combination with the 125 hp Continental engine, the Eclipse sports an alleged 138-knot cruise speed. More on that later.

Fuel goes aboard the Eclipse through a single filler at aft left fuselage into a 24-gallon tank mounted behind the cabin. There's only one tank, so there are only two positions, on or off.

The overhead canopy is hinged at the rear and folds up and back to provide ultimate access to the cockpit. You merely step over the sidewall and settle into the seat. As you might imagine, visibility is exceptional with nearly a 360-degree view, but the price of the semi-bubble canopy is a greenhouse effect in hot weather. There are small vent windows on each side that may be opened in flight. Once you've buckled up the four-point harness, you definitely feel as if you're a part of the airplane.

Diamond has a slightly different philosophy about seating comfort in that the seats are fixed and the rudder pedals are adjustable. This has the benefit of providing good crash protection, as the 26G seat is hard mounted to the airframe. There's no provision for changing the geometry of the stick to accommodate an individual pilot's arm length, however.

The C1 employs a nonsteerable nosewheel, and to my mind, that's the best possible compromise between a tailwheel and a steerable nosewheel. The free-wheeling forward gear allows unusually responsive directional control. You can reverse direction in the C1's wingspan, though locked-wheel turns aren't recommended. Pretty obviously, directional control is by differential braking until the rudder takes effect, and that means more wear and tear on the brakes, a reasonable price in exchange for such positive ground maneuvering.

It's more than coincidence that the Eclipse shares many characteristics with the company's Diamond Star, a popular four-seater that's made a name for itself as a simple and fun family traveling machine. The Star is a logical step up from the Eclipse, exactly the way Diamond planned it. The panels are laid out almost identically, the interiors look almost like exact copies, and the two airplanes look very similar on the ramp.

One thing the two Diamonds don't have in common, however, is IFR certification. The DA40 Star is IFR certified: The DA20 Eclipse isn't. That's because the DA20 doesn't have adequate lightning protection. You can equip the Eclipse for IFR flight and train for the rating under the hood, but the DA20 isn't approved for operation in actual IMC.

Both the Star and the Eclipse also share excellent in-flight handling, partially a function of the allegedly old-fashioned center stick. Perhaps for that very reason, the DA20's formation manners are among the best. I've flown photo formation in a variety of airplanes, and the Eclipse is one of the easiest machines there is if you need to hold station 30 feet from a photo ship. It's fast enough to stay with most photo platforms, the visibility is impressive and, to my mind, the stick is in an ideal position to allow good control in formation.

I'm aware that side sticks are all the rage these days, and I've flown my share of airplanes equipped with pitch/roll control sticks mounted on the sidewall (right up to and including the F-16). In general aviation applications, they offer a fun alternative to a conventional yoke, often with armrests that mold to your forearm and allow you to fly the airplane primarily by wrist.

Still, center sticks do offer a few advantages. A conventional joystick provides more mechanical advantage with the opportunity to put your bicep into play. Side sticks confine pitch and roll control to the outboard hand, regardless of whether you're left- or right-handed. Did you ever try to fly a left side stick with your right hand? Highly unlikely.

The stick is one reason the USAF chose the Diamond C1 as its aircraft for the Initial Flight Screening contract with Air Force Academy cadets in Colorado Springs, Colo. The USAF evaluated students by placing them in the right seat, with their right hand on the stick and left on the throttle, fighter-pilot style. The concept is known as HOTAS, Hands On Stick And Throttle, and it relies on the fact that the vast majority of pilots are right-handed.

Another benefit of the Eclipse is its power. Like the Liberty XL-2, the Eclipse flies behind 125 hp, another reason the Air Force was induced to buy the C1 Falcon version for operation at Colorado Springs, elevation 6,200 feet. (These were essentially the same airplanes but with smaller fuel tanks to allow a better payload and a full set of flight instruments on the right side rather than the left.) There's no turbo out front, but short of that, the C1 offers reasonable power on even a warm day in Colorado.

Standard climb at sea level/gross is listed as 1,000 fpm, and service ceiling is claimed to be above 13,000 feet. This suggests reasonable performance at low to medium altitudes where most flight training is conducted.

The little Diamond isn't quite as quick as its PR might suggest, but by any measure, it's a fast machine for a single with wheels hanging in the wind and only 125 hp to protect it. Plan on an easy 130-135 knots at 75% power and 8,500 feet MSL. Best of all, that's on only 6.0 gph, generating a nautical mpg rating of about 22. In automotive terms, that's 25 statute mpg, easily the equal of most SUVs.

Landings require a little attitude adjustment in the Diamond C1. Perhaps because of Diamond's experience building powered gliders, the C1's efficient, high-aspect-ratio wing enjoys a better L/D than most other general aviation airplanes, about 11 to one. In contrast, the Cessna 150/152, perhaps the standard of the world for flight training, has a glide ratio of seven to one. This means approaches in an Eclipse are slightly flatter than in a Cessna. It also means the Eclipse can glide farther in the event of engine trouble, fortunately not a common problem for the durable little Continentals.

Though I've never been much more than a licensed student myself, I've been reintroduced to the true student mentality in the last year. Peggy is probably typical in placing major concern on the smoothness of her landings.

The 152 is certainly an easy airplane to return to Earth, but I would bet the Diamond Eclipse would be even easier. The combination of the enhanced ground effect of a low wing, ultimate visibility of a bubble canopy and joystick control make the C1 a truly lovable teaching machine. With such a low, full-flap stall speed (42 knots), you could conceivably truck down final at 51 knots without violating the 1.2 Vso rule, and slower is nearly always better. Recommended approach is more like 55-60 knots, and the pay-off in the C1 is so predictable, students wind up loving the type almost as much as instructor Rob Johnson and I do.

As Pilot Peggy approaches her private pilot flight test in the Cessna 152, I can only wish she'd been able to fly an Eclipse for her course of study. Nothing wrong with the 152; it has certainly earned its stripes as one of the hardest-working airplanes in general aviation. To my way of thinking, the Eclipse would simply have made the process more fun.