Ready, Set… by Paul Bertorelli Weve heard this story twice from separate sources: A Diamond salesman demonstrating the companys new turbodiesel DA42 Twin Star drives the thing a couple of miles offshore over the Gulf of Mexico at 1500 feet and cages one engine. “Now,” he says to the wide-eyed would-be buyer, “would you rather have that other engine out there or a parachute?” This, we are told, is an effective deal closer if the buyer happens to also be kicking Cirrus tires. Have things gotten so cutthroat in the new aircraft business that sales folk would actually stoop to such tactics? Not only do they stoop, they revel and it has always been so. Twins have traditionally been pitched as step-ups from singles-higher, farther, faster and carry more stuff-but they havent often been sold against singles. But thats exactly the strategy Diamond seems to be taking, with a sales slogan that promises the reliability of a twin and the economy of a single, something we havent seen before. Can Diamond really deliver on that claim or is it just so much sales hype? And with regard to safety, how does the Twin Star stack up against the BRS-equipped Cirrus SR22? Can the comparison even be made? We set out to answer those questions and our findings surprised us.
by Paul Bertorelli
Weve heard this story twice from separate sources: A Diamond salesman demonstrating the companys new turbodiesel DA42 Twin Star drives the thing a couple of miles offshore over the Gulf of Mexico at 1500 feet and cages one engine. “Now,” he says to the wide-eyed would-be buyer, “would you rather have that other engine out there or a parachute?” This, we are told, is an effective deal closer if the buyer happens to also be kicking Cirrus tires.
Have things gotten so cutthroat in the new aircraft business that sales folk would actually stoop to such tactics? Not only do they stoop, they revel and it has always been so. Twins have traditionally been pitched as step-ups from singles-higher, farther, faster and carry more stuff-but they havent often been sold against singles. But thats exactly the strategy Diamond seems to be taking, with a sales slogan that promises the reliability of a twin and the economy of a single, something we havent seen before. Can Diamond really deliver on that claim or is it just so much sales hype? And with regard to safety, how does the Twin Star stack up against the BRS-equipped Cirrus SR22? Can the comparison even be made? We set out to answer those questions and our findings surprised us.
Comparing a twin and a single with the word “economy” anywhere in the same paragraph has, heretofore, been absurd. If you own a twin-or want to-$500 fill-ups are couch change. Thats why sales of twins are soft and no one has certified a new piston twin since Cessnas 303 in the early 1980s. In a bold stroke that appeared to border on the delusional, Diamond announced the Twin Star in 2002 and in so doing, it broke one of the unwritten rules of aircraft development: Dont marry an untried engine to an equally new airframe. To tweak the nose of fate with an extra twist, the new engines would be Jet-A-burning diesels.
Not only did Diamond prevail with this design, it did so quickly and within four years, the airplane has become a strong seller, especially in Europe and Asia. In those markets, where even Jet-A is $6 to $8 a gallon, the Twin Stars high selling point is economy and ready availability of fuel supplies. Diamond sensed tepid interest in diesels in the U.S., where we seem bent on eliminating any vestiges of underground hydrocarbons. But here, too, demand has proven surprisingly strong.
But theres a problem. Compared to other airplanes in its price range-the Cirrus SR22, the Columbia models and Mooneys-the Twin Star is a bit of a slug. It gives up 10 to 15 knots to the Cirrus and 40 to 60 knots to the turbocharged Mooneys and Columbia. Never mind that the Twin Stars impressive range means it can occasionally beat the others by skipping a fuel stop, U.S. buyers crave speed, ostensibly because we live in a big country but, in reality, its the usual guy thing. Mines faster than yours, even if you do get there first.
But the need for speed shrivels at the prospect of a lunched engine turning the airplane into a glider, at which point bravado turns to a whimpering wish for a solid Plan B. And thats one reason why the Cirrus CAPs/BRS has been such an elemental part of the Cirrus success story. The airplane is a terrific performer and boy, that parachute makes it safe, too. Sold.
Diamond sees the same opening for its Twin Star. Its not as terrific a performer as the Cirrus, but would you rather your Plan B be a non-event landing on one engine at an airport or a crash through the trees under a 2400-square foot canopy that you cant steer, asks Diamond?Basic Airplanes
The SR22 and DA42 compare favorably in that both are all-composite low-wing airplanes with state-of-the-art avionics and safety systems. With the exception of the CAPs parachute-unique to the Cirrus-both can be similarly equipped. The Cirrus is equipped with Avidynes Entegra EFIS system while the DA42 has Garmins G1000. Both airplanes can have ice protection, weatherlink, traffic systems, terrain warning systems and engine monitoring capability.
For like airplanes, the Twin Star is substantially more expensive: Typically equipped, it invoices at about $571,281 versus $439,000 for a well-equipped Cirrus SR22. At Oshkosh, Cirrus announced the availability of a turbonormalized SR22, the addition of which will push the total cost to about $500,000 or a bit over. If past buying patterns are any indication, the majority of buyers will opt for faster, better equipped airplanes. In this article, weve compared only the normally aspirated version of the Cirrus, since the turbo performance numbers arent available yet.
And speaking of numbers, heres the summary, based on our recent test flights in both aircraft. We flew the DA42 with flight instructor Bruce Batelaan at Europe-American Aviation in Naples, Florida. (See sidebar.) To the credit of both companies, the POH claims are generally accurate and, in the case of Diamond, conservative on some counts. Both companies inflate cruise speeds in their promotional material, but we (and buyers) have learned to expect that.
In a nutshell, the SR22-G2 is a 170- to 180-knot airplane burning between 16 and 18 GPH, with 17 GPH being a practical median. For the economy minded, the airplane does quite well at lower power settings, burning 14 GPH to generate about 170 knots at 14,000 feet. At the higher power settings-we used 71 percent power-its still air range with a 45-minute reserve is just over 700 miles. Pull it back to 60 percent power and the airplane will do 850 miles.
A persistent article of faith in GA is that four-place airplanes arent full seats/full tanks sorts of machines, but the SR22 is close. It will carry four 170-pounders, plus all but about a couple of gallons of gas. Offload enough for 50 pounds of baggage and you can still fly 600 miles.
By comparison, the DA42 is a 160- to 165-knot airplane, burning a miserly 12 gallons of Jet-A. Weve been told by demo pilots that theyve “seen” 170 knots true in the DA42, but we havent. Standard tanks in the Twin Star are 50 gallons, which is enough for about 535 miles in still air. With the optional tanks-76 gallons useful-the range goes to 834 miles at the 80 percent power setting that delivers mid-160s cruise speeds. Throttling back the diesels stretches the range more than it does for the gasoline engines. Sixty percent power in the DA42 delivers about 145 knots on 8.6 GPH, for nearly an 1100-mile range. But youd be in the airplane for more than seven hours. The non-turbo Cirrus cant come close to that non-stop max range effort.
Loadwise, because it needs to tanker less fuel, the DA42 has a payload advantage, but is range limited with standard tanks. With full standard tanks, it can carry the four people and a max baggage load of about 155 pounds for 535 miles. With long-range tanks full and the four people, the situation reverses: The DA42 outdistances the Cirrus, even with the some of the bags.
Summary: The Cirrus gets there faster than the Twin Star-about 18 minutes on a 600-mile trip-but burns 13 gallons more, or about $60 at current fuel prices. Compared to a Twin Star with standard tanks, the Cirrus has better range. But with long range tanks, the Twin Star does and it also enjoys more loading flexibility.Cost of Go
Traditionally, economic comparisons of twins and singles fall apart on two points: the higher fuel burn and the cost of overhauling the second engine. The twins additional speed doesnt begin to offset the cost Delta. Interestingly, the diesels appear to turn that around. Heres the math: At a fuel price of $4.25 for avgas and a $30,000 overhaul price for the Cirrus IO-550, direct operating cost works out to $87.25. Thats $15 for the engine and $72.25 in fuel.
Because the Thielert Centurions dont yet have an established final TBR-time between replacement-Thielert is pro-rating them based on a 2400-hour TBR at $12 per hour, or $38,800 for replacement, not including prop. Obviously, it takes two engines so the cost per hour for both engines is $28, to include props. Although thats higher than the Continentals hourly cost, Jet-A is usually cheaper than avgas-we used $4.11-and the Thielerts burn enough less of it to amount to a $77.20 direct hourly cost for both engines, or about 11 percent less than the Cirrus. With its retractable landing gear, the DA42 may or may not eat up some of that in maintenance. Its too soon to tell. But call the operating costs close to a wash. We dont yet know if Thielerts engine prices are artificially depressed-only long term experience will reveal that-but Thielerts costs (and quality) are driven by the high-volume automotive supply chain whose core costs are lower than Continentals. Still, long-term maintenance costs on the Thielerts are unknown; they remain relatively unproven engines.Accident Record, Safety
Diamond can reasonably claim the high ground on lower or at least equivalent direct operating costs while touting the reliability of a second engine. But the one-engine-versus-two debate has been argued ad nauseum and remains unsettled, largely because it enters the muddy realm of perceived safety versus proven accident record. The Cirrus parachute changes this equation, but exactly how is difficult to quantify.
Our most recent review of the Cirrus accident record shows it to be improving after a spate of early fatal accidents. Based on hours data provided by Cirrus, the overall Cirrus accident rate is 4.1/100,000 hours, with a fatal rate of 1.4/100,000. The overall rate is below the GA average of 6.2, the fatal rate slightly higher than the 1.2 GA average. To date, there have been seven Cirrus CAPs deployments and 13 occupants of those airplanes have walked away, most without a scratch. One can debate the righteousness of using the parachute in some of those accidents but the fact remains, four were loss-of-control incidents that might well have been fatal without the parachute. Had they been, the Cirrus fatal accident rate would be measurably higher so, in that sense alone, the parachute has proven a resounding success.
By comparison, the DA42 has no safety record; its too new. But Diamond as a company, with its DA20 and DA40, owns what we consider to be the best safety record in general aviation. These aircraft have what appear to be unbeatably low overall and fatal accident rates and although the competition sniffs that Katanas and Stars arent nearly the same as Cirri and Mooneys, Diamonds are still subject to the laws of gravity and the tricks of stupid pilots. Unknown is whether the Twin Star will contribute to that sterling record or tarnish it with a run of accidents. In its favor, the Twin Star may be the easiest handling piston twin ever made, with single-lever throttles and switch-it-on/switch-it-off FADEC engine management that really works. But its just as easy to secure the wrong engine in a Twin Star as in a Seminole.
Perceived safety is, of course, between the ears. Over a long stretch of water, a night IMC trip or flight in mountains, we think for a trained and competent pilot, the second engine is a genuine plus. In our view, it would be of more comfort than the parachute. But the second engine does nothing to protect against structural failure, unrecoverable loss of control or a mid-air collision, all calamities the parachute is intended to address and has.Conclusion
We balked at Diamonds early claims that it could go after Cirrus with the Twin Star, but on closer examination, the numbers seem plausible to us. We are still watching the economic performance of the Thielert engines closely, however. We suspect in the narrow universe that both companies market to, theres an overlap of buyers sophisticated enough to understand the risk tradeoff between the parachute and the second engine and realistic enough to know that a second motor isnt a benign benefactor. It takes skill and recurrent training to realize its benefits.
In our view, Cirrus has become a dominant force in GA because it has delivered what it said it would: Good performance and perceived safety that resonates both with experienced buyers and those new to aviation. Its actual accident pattern is slowly coming into line with expectations.
In this context, what we think the Twin Star most needs is another 10 to 15 knots of speed; it runs in a fast crowd and it will need to keep up. At Oshkosh, Diamond CEO Christian Dries hinted that such a thing may very well be in the works, although he declined to offer details.