Stemming from their sailplane heritage, Diamonds are we’ll known for slender graceful T-tails and long efficient wings. And like my cute little Diamond Katana that I earned my private certificate in nearly 25 years ago, Diamond’s latest DA50 RG is many things visually.
But unlike the Katana trainer, the muscular and aggressively styled DA50 RG is far from cute. This airplane growls muscle car ramp appeal—from its chiseled cowl to its gull wing doors and massive control surfaces.
But looks aren’t everything, so to find out if the DA50 RG has the performance to match (and how a pilot with no retrac or complex experience might transition), I slipped into the all-carbon-composite Continental CD-300-powered retrac while the airplane was touring the U.S. with LifeStyle Aviation, the North Carolina-based largest U.S. Diamond dealer.
A BIG SINGLE
The DA50 RG originates from the fixed-gear DA50 introduced somewhere around 2007, and certified with the CD-300 six-cylinder turbocharged liquid-cooled FADEC diesel engine in 2020. Today that engine lives under the long cowling of the DA50 RG and the first time you walk up to the airplane you’re struck at how large it is. That’s significant because it might not fit in a typical T-hangar. The wingspan is 44 feet and the T-tail is nearly 10 feet tall. At 6 foot 2 inches, I couldn’t reach the tail without a step ladder. Moreover, the pilot-side passenger and cargo opening is astonishingly large and capable of swallowing bicycles, skis and snowboards, golf clubs and even collapsible kayaks.
Ingressing the DA50 RG is made simple by the smartly located molded handholds located just aft of the cargo area. Swing your legs around the control stick (Diamonds don’t use yokes) and you’re in. The seat is not adjustable forward/aft for safety reasons, and it’s permanently fixed over the wing spar and cockpit supports to help absorb energy in case of a hard landing or crash. Instead, the rudder pedals electrically adjust at the push of a conveniently located button to exactly the position you need to comfortably work the rudder and toe brakes. The seats recline to a nearly horizontal position (Diamond’s chief pilot and head of flight operations, Martin Scherrer, jokingly referred to it as “cruise mode”) and a passenger in the copilot seat could easily move their rudder pedals all the way forward and recline the seat all the way back to get a little shut-eye during those long trips.
SYSTEMS, COCKPIT, CABIN
The DA50 RG’s CD-300 turbodiesel is mated to a three-blade MT composite propeller. Jet A fuel is fed exclusively (except during an emergency) from the left wing tank, so occasionally a cross-feed from the right tank is needed. The center console armrest covers the manual fuel switch for normal, emergency and off positions, and it’s hard to say whether that’s a smart use of space or a dangerous distraction in the event of a fuel or inflight fire emergency.
What is smart is that the optional keypad controller for the Garmin G1000 NXi flips out of that center armrest. This is such a convenient location for entering data into the big Garmin screens that it really ought to be standard equipment like it is on Garmin Perspective-equipped Cirrus models.
The rest of the panel switchology is fairly logical and the flow is natural. The engine start and main electrical switches are directly in front of the pilot under the left-hand G1000 NXi, a VHF radio and GFC 700 autopilot switches in vertical layout and the backup electronic attitude indicator and airspeed/altimeter between in the dead center of the panel.
The rear seating seemed to be comfortable, but I would think that three adults might be a bit cramped. Is this a five-place plane? Perhaps for short flights, but a maximum of four seems more likely for long cross-countries. Useful load for the demo plane (optionally equipped) is not enormous at 1100 pounds, but is sufficient for full tanks (51.5 gallons and 49 usable), four average-sized adults (180 pounds) and more than 30 pounds of baggage.
FLYING IT
The engine start-up procedure is stone simple—throttle to idle, engine master on, press and hold the start button for five to 10 seconds until it starts. And here’s where the DA50 RG loses some of its hard-won aggressive attitude because even with 300 HP, the CD-300 engine and three-blade MT prop are surprisingly quiet. Jon Gutekunst—LifeStyle’s demo pilot—and I were able to carry on a conversation at normal talking levels without headsets and with both forward doors open.
Taxiing the big Diamond single is easy, with the differential toe brakes providing good directional control, plus the throttle is light and responsive. During 90-degree turns in the taxi, I needed more power than I was used to in my Grumman Tiger, probably due to the weight of the much larger engine over the castering nosegear. But once the DA50 RG gets rolling in the right direction, the power can come right back down to just a touch above flight idle. A nice cabin luxury during taxiing is the optional electric air conditioning, which runs on a separate alternator that serves double duty in an emergency to back up the primary unit.
The before takeoff engine run- up doesn’t get simpler. Two flicks of the FADEC switch ensures both Engine Control Units (ECUs) are working and then a long press of the self-test—where the computers take control of the engine and briefly increase RPM—ensures all systems are good to go and then it powers back down to flight idle. The whole process took maybe 20 seconds total. Before you go, set the slotted Fowler flaps for takeoff and make sure the cowl flaps are open for extra cooling; they’re generally only open during takeoff, climb and landing.
The 300 horsepower quickly puts the airplane at the 70-knot rotation speed and it levitates off the runway. In a gusty crosswind, the controls (pushrod design) felt heavy in pitch while I hunted around for the correct rudder (cable design) input. But after quickly straightening it out, the airplane gets right into the 100-knot climb. You want to pull the engine back to max continuous (90 percent or 270 HP) and Diamond recommends no more than five minutes at full power, or 300 HP, for takeoff. But even though we were not at VY (79 KIAS) and with 90 percent power and a density altitude in excess of 3000 feet, the plane easily climbed out at roughly 1200 FPM. And with twin turbos and a constant-speed prop, the climb performance remains relatively constant up to respectable altitudes. The DA50 RG’s listed operating ceiling is 20,000 feet and it comes equipped with a five-place built-in Aerox oxygen system.
There’s no need to worry about cylinder head temperatures. The CD-300’s liquid cooling ensures constant cooling performance regardless of the airplane’s attitude, engine power or airflow through the cowling (though what happens in case of a cooling system leak might be an area to investigate).
With the GFC 700 autopilot engaged, I took a look around the cabin and was impressed with its spaciousness, with an SUV-like feel. Cabin headroom is more than ample and the seats are comfortable. The circuit breakers on the far right of the panel are a bit of a reach, and the overhead controls and vents for the air conditioning and oxygen were unobtrusive and easily accessed. Visibility out the forward windscreen is only marginally hampered by the slender center post; of more concern were the wider side supports, which required some active head movements to gain visibility around for side scans.
EFFICIENCY COMPARISONS
At max economy settings at 10,000 feet (45 percent power, 127 knots true and 7.9 GPH), full fuel tanks could keep you aloft for more than five hours or about 650 NM (with reserves), which is probably a longer time than you really want to be sitting in a small piston single, no matter how luxurious. Another option, if going fast is more your thing, is to set the best-speed setting (90 percent power, 172 knots true and 15.9 GPH), which would only allow you to stay up for 2.5 hours or so (with reserves) but travel over 400 NM. Or you could use Diamond’s recommended cruise setting of 75 percent power, which compromises fuel economy with speed, and you’d be traveling at 160 knots true and burning 12.4 GPH. Figure on roughly three hours of endurance (with reserves) and travel almost 500 NM. Obviously, to get best performance, you’d want to take advantage of the twin turbos and go as high as reasonably possible. As another example from the book, at 18,000 feet and 60 percent power, you can go 156 knots true on 11 GPH and cover 550 NM on a 3.5-hour flight.
Worth mentioning is that those numbers (down low, of course) are only marginally better than my fixed-gear Grumman Tiger. It’ll do 138 knots true on 10.5 GPH, flying for roughly four hours with reserves and covering around 550 NM. Sure, the simple Tiger costs about 15 percent of the DA50 RG. But wow—what a difference in top speed, ramp appeal and modern creature comforts.
Where DA50 RG flight performance really shines is during climb. With its twin turbos, you continue to climb at 700 to 1000 FPM from sea level to 14,000 feet and 500-plus FPM above that almost to the 20,000-foot operating ceiling. That’s at VY (79 KIAS) and strangely, Diamond does not list a separate VX. Cruise climb is considered to be 94 KIAS and you only lose around 200 FPM of climb by traveling over the ground quite a bit faster. To put it into perspective using the fixed-pitch-prop and normally aspirated Tiger again as an example, it takes me about 40 minutes of steady reduced climbing and continuous tweaking of the mixture to claw my way to a maximum altitude of 15,600 feet. In the Diamond DA50 RG, I could reach that in about 15 minutes and let the FADEC do all the hard work for me.
HANDLING
In roll, the DA50 RG is fingertip pressure sensitive—pretty much just think about rolling and it will. Pitch inputs to maintain altitude require a bit more back pressure, but the rudder was we’ll harmonized and the nose did not show any tendency to hunt during the turns. We did one 360-degree turn to the left and another to the right and I managed to maintain altitude fairly we’ll (though perhaps not we’ll enough to pass a commercial checkride).
Still, hand-flying in the DA50 RG is enjoyable—it feels stable, yet very responsive to control inputs. I did another 45-degree bank turn to try out the envelope protection in Garmin’s GFC 700 autopilot, where in case of spatial disorientation, pressing that blue button will return the plane to straight and level flight. It worked pretty much as advertised and I was pleasantly surprised that while the return was firm and crisp, it was not so jarring as to further upset an already harried pilot.
The rudder trim control is conveniently located on the front of the throttle, while the elevator pitch trim can be controlled electrically from the switch on top of the control stick or manually via a standard control wheel in the center console.
Trying some stalls, I found that the double-slotted flaps really help slow the slick composite airframe down—useful for graciously fitting into the traffic pattern. Smoothly pulling off the power and increasing the angle of attack quickly approached the low stall speed (VSO) of 52 KIAS.
The DA50 RG’s VLO/LE (max landing gear operating/extension speed) is 162 KIAS—also helpful for slowing it down early. The actual stall and recovery was a complete non-event—docile and benign with straightforward recovery—nose down, throttle up, flaps up and gear up. We were completely recovered and climbing again after only about a 200- to 300-foot loss in altitude.
Heading northeast towards John C. Tune Airport in Nashville, Tennessee, afforded a good time to do a practice ILS approach to a full-stop landing, while also getting a feel for the G1000 NXi’s FMS keypad in the center armrest to program the approach. The flight director guidance and synthetic vision (Garmin SVT) on the G1000 NXi displayed the boxes in the sky for us to fly through, the GFC 700 did a great job of keeping us going in the right direction and our only input was to make small power corrections from time to time.
I noticed during the approach that in spite of a decent amount of light to moderate chop that had rattled me around pretty good during my flight up in my Tiger, the DA50 RG was very stable and did not exhibit any of the Tiger’s bouncy behavior. The Diamond seems to be an excellent IFR platform—well-equipped, well-behaved and well-appointed.
LANDING IT
With the flaps and landing gear down, the approach through the haze in a gusty crosswind went fine until I disengaged the autopilot. The DA50 RG handled we’ll in roll, but the heavy pitch force showed itself and it didn’t help that I was carrying a bit too much speed. I was saved by Jon’s presence and coaching, plus the trailing link landing gear that acts like margarine for below-average landings. Braking was effective and we were easily slowed down in time to take the exit that the tower instructed.
As we taxied to a semi-remote part of the ramp for a photo shoot, I thought about how I was going to summarize this plane. As an instrument-rated pilot with zero complex or high-performance time, the DA50 RG was a huge step up but did not feel intimidating thanks to its FADEC engine controls, logically configured instrument panel and the power of the G1000 NXi with the GFC 700 autopilot.
The safety features of the fuel tanks protected by the twin spars (see the Aviation Consumer March 2023 feature on composites safety for more details), optional TKS anti-ice system, plus 26-G crashworthiness seat design and embedded autopilot with envelope protection are important considerations as well.
The DA50 RG is not the fastest single-engine piston out there nor the cheapest and at $1.15 million list, the cost is one of the DA50 RG’s biggest knocks. It doesn’t have the biggest useful load nor the best fuel economy (though the cheaper Jet A helps), but what it does, it does fantastically well. Its lightweight yet strong and low-drag carbon/epoxy airframe transports up to five people and their things up to altitude quickly and then cruises at a reasonably fast speed safely and in climate-controlled comfort that borders on luxurious, with space to spare. Plus, there’s no shortage of hulking ramp appeal.
Visit www.diamondaircraft.com.
