Plastic Planes, Part One: The Diamond DA40 Star
Three all-new composite, four-seat, IFR singles are or soon will be available on the U.S. market: The Diamond DA40 Star, the Cirrus SR-20 and the Lancair Columbia 300. Other than the composite materials from which they are made, each is different: Different powerplants, different equipment and different markets. AVweb's Dave Higdon managed to put the three through their paces — all in the same week. In this first of a four-part series, he tackles the Diamond DA40 Star.
Diamond's New Star, the DA40: More than a Katana All Grown Up
Is it safe? That's generally a good question to ask before any flight in the first of anything: The newer the program, the more daring the design, the more important the question. But rolling the prototype DA40 from base to final at the Plant City (Fla.) Municipal Airport, the last worry on my mind was whether flying it risked more than letters from an angry manufacturer or the respect of readers. Before my turn came to engage the starter of the Star's Lycoming engine, pilots with Diamond Aircraft in both Austria and North America had racked up a monstrous number of landings and takeoffs, as well as an impressive number of hours along the way: 16,000-plus circuits totaling more than 1,100 hours. The abuse is part of Diamond's cleverly named BETA program — Best Ever Tested Airplane.
Why a BETA program? Diamond's execs want to confidently boast of the Star's status as the best-tested new general aviation airplane ever, one with an airframe designed with fail-safe integrity. Judging by the numbers — dozens of sets of tires and brakes, several fuel pumps, scores of oil and filter changes, plus the wear-and-tear of high use on the example I flew — the Star prototype suffered a long-lasting array of abuses from others far less benign than me, well before my turn in the left seat. The bird survived the abuse without embarrassment. And if it held together for them, it should stay together for me. Diamond designed the airframe for unlimited life; even 2,000 hours falls far short for even life-limited airframes.
Double-dribbling down a runway, on the other hand, always embarrasses me because, usually, I can do better. But there were no embarrassing bounces on my first two touchdowns at Plant City, both of them in stiff, rowdy winds about 70 degrees cross to the runway. In fact, I got my best two-out-of-three first. So, after two, quitting seemed prudent. Still, it was hard to imagine not blowing the third one simply because surprises sometimes distract me — and little surprises me more than making a couple of brag-worthy touchdowns right off the bat, in an airplane new to me. Of course, the Leprechaun, my mechanic buddy, ascribes to a standing theory: credit for me looking good in a landing must belong to the airplane. The Leprechaun may be right, in this case, a perspective far more noteworthy than a couple of strokes of timing by a big kid with playing with a new toy.
If a plane can make me look good, chances are it can make most pilots look great. And of the three new composite airplanes available today, the Diamond DA40 Star exhibited the least-demanding, most-forgiving attitude of all. From my perspective, the Star's blend of speed, utility and harmony makes it the best prospect for use in basic and advanced flight training, since the demands it makes on a pilot are no more or less demanding than the basic requirements to stay ahead of the airplane.
Now to give away an old test-pilot's family secret to enjoying any airplane: Follow its numbers, keep a light grip on the stick, at least one eye on the centerline all the way through flare, and enjoy yourself. You may need a second or third try to refine your touch and timing, but you shouldn't suffer any surprises. Oh, and you're supposed to have fun.
In a case of less truly being more, keeping my touch light and relaxed only made the Star feel more connected. Fewer fingers, far less opportunity to over-finesse and over-control, and far more sense of how finely the Star flies when handled lightly. These traits exist at a level that could challenge the mainstays of flight schools and rental counters today. Although it suffers a price disadvantage, methinks Stars will frequently find fine homes on ramps where Skyhawks and SPs and Archers dominate today — and deliver a look, impart a feel, and provide performance superior to anything else flying behind only 180 horsepower today. The handling is there; so is the forgiveness; ditto for the performance — the best in its class.
Despite the appearance of suffering obvious, repeated mishandling at the hands of some unknown abusers, the Star's right-and-light control balance should make it a confidence builder in the hands of a relaxed, comfortable CFI and all but perhaps the least intuitive students among us. But for the rest of the pilot population, neither students nor those otherwise employed in torture testing airplanes, transitioning from yokes or other sticks should pose no problem if they approach the task with a relaxed, open mind. Remember, learning new things is part of the fun, whether a new rating or a new type.
And learning about the Diamond Star was one of those experiences that keeps my work fun.
A New Star Is Born
My short morning drive to Plant City from Lakeland simply spiced my attitude for flying Diamond's highly anticipated new design: a clear sky, benign cumulus here and there. So forgive me if my mindset at flying the Star was one expecting to have some fun while satisfying my professional and personal curiosity. Earlier, sitting in a mock-up reaffirmed my memories of the Star from the prior year's AirVenture: roomy, well-thought-out and with an unusual two-door configuration — both on the port side, one for the front seats, one for the back. Twin center sticks, adjustable rudder pedals, a convenient console and comfortable seating complement large windows and a well-equipped panel with plenty of space for all the goodies a new owner would want. An injected IO-360 Lycoming making 180 horsepower and the plane's empty and gross weights put it in close company with the Comanche 180 I fly, and those similarities further piqued my curiosity. What could be more fun?
In conflict with my let's-have-fun attitude was the knowledge that the wind would be blowing well off the runway heading, the air would be bumpy and, since some pilots already considered the Star a tad touchy, the plane would prove a bit prone to bouncing in the bumps. That's why we fly these birds — to divine some truth from our experience to counter the incessant hangar flying and instant expertise of some more prone to generating hot air than flying in it.
As usual, much of the scuttlebutt proved out — but much didn't, mostly in a couple of negatives offered me by otherwise sincere, trying-to-be-helpful folks. Worrying about a perception of the Star as a sensitive airplane might have spoiled a good time. In the end, however, the Star's combination of precise, crisp flight controls and nimble response made my transition an easy one and the experience pleasant and comfortable, despite the warm conditions and my unfamiliarity. Students and veterans alike, at least those lacking an automatic iron grip, should find the Star fun to fly, with enough utility to make it as versatile as airplanes tend to get. And that versatility and performance should make the Star a strong contender against today's similar market contenders, both of conventional and similarly unconventional genes.
Comfortingly responsive without any tendency toward excessive reaction, the DA40's appeal to flight students takes no great leap of imagination. Picture students of all ages whetted by Microsoft Flight Simulator and expensive feed-back joysticks and the fighter-like center stick of the Star becomes largely a non-issue, particularly considering its intuitive nature, precise feel and the proportional control pressures I experienced during my flight.
Now, imagine friends and families launching off for a long weekend, or a couple off on an adventure in paradise. The Star has that potential, as well. And with its forthcoming IFR approval, there's little this plane can't do that any other in its class does — and some things it will do better.
Simple, Sturdy Systems Make for a Durable Delight
Let's face it: More than 16,000 landings — as of last spring — puts the Star prototype far ahead of most private planes in private hands, longtime trainers excepted. Thanks to a tall windshield and a cowl that slopes downhill to the engine inlets, more than a few pilots sampling the Star for the first time found themselves over-rotating at both ends of a flight, dragging the skid, bouncing the gear, mashing the tires, straining fittings and fasteners all over the airplane.
All the more reason for a thorough walk-around. But in my extensive preflight of the Star, nothing stood out as showing any abnormal wear save, maybe, for that replaceable tailskid, poor thing. In fact, that unusually big view out of the cabin and many pilots' visual dependency on timing rotation, climb angle and flare probably helped create the Star's reputation for twitchy response, over-rotation tendencies and control sensitivity. Hard to look at that visibly-scarred tailskid and not worry. Scarring skids is not an uncommon outcome for pilots new to a plane. For proof, check the skids and tail tiedown rings on Cherokees, Musketeers, Tigers and Tomahawks.
During the preflight, control linkages, hinges, tires, oil and fuel were all easy to touch and check. Ditto for the lights. With fuel, oil and air all right, it's time to climb inside.
But, even inside, the Star showed little wear and tear for the abuse doled out to it — and particularly little considering the volume of people entering and exiting the cabin. Of help are the large doors and the built-in handholds for seats, front and back. No need to stand on upholstery, lean on the panel or trip on a control stick. Compared to the Cessna singles, with their two front-seat doors, the New Piper, with its single cabin door, or the Tiger, with its sliding canopy, rear-seat access is a particular joy — even though right-seat flyers up front must navigate over a console to park and strap in.
But, once seated and belted, all controls fall nicely to hand, particularly the fuel and electrical controls. Adjustable rudder pedals allow the seats to be fixed in place, simplifying the process of meeting FAR 23's 26-G crashworthiness requirements when compared to adjustable ones. And the seats do allow some additional adjustment by changing the thickness of the cushions for seat bottoms and backs.
Starting the 180-horse engine — the lowest power rating of the three new composites AVweb flew for this series — is typical for injected Lycomings: Pull the mixture to idle cutoff, use the boost pump only long enough to move the fuel pressure needle into the green, turn off the boost pump, hit the starter and advance the mixture control when the engine catches. Sounds harder than it is. But the technique works, even for hot starts, and the Star roared to life after about five of the three blades of its MT constant-speed prop went by the cowling, settling into a comfortable idle. Aiding the Star's easy starting is the first OEM installation of Unison's LASAR full-authority digital ignition system. The LASAR system also enhances the Star's fuel efficiency — but more on that later.
While the engine warmed and we waited for our clearance, the Star endured my engine-run-up procedure, as it had for so many others so many other times. Again, no surprises; the LASAR ignition works seamlessly with the engine and you probably would never notice the difference — I never did.
One thing pilots will notice is the Star's nosegear and steering: a castering nosewheel that responds only to differential braking of the mains. Theoretically, differential braking suffers from the disadvantage of wearing out brake pads and discs faster than on aircraft with nosegear steering. Conversely, nosegear steering adds weight, complexity and maintenance considerations to an airplane.
All three plastic designs flown for this series — the Cirrus SR20, Lancair Columbia 300 and this Diamond Star — use castering nose wheels, and it's almost a coin toss between the DA40 and SR20 for easiest to drive on the ground. If the Star enjoys any edge, it seems likely to stem mostly from lighter weight, since the geometry appears so similar between the two. Overall, it proved a non-issue.
Long Wing + Quick Acceleration = Short Roll
The airport at Plant City, Fla., doesn't exactly overwhelm visitors with the length of its 3,950-foot runway but for the Diamond Star, just over half was all we needed to counter gravity. Holding the centerline with differential braking lasted scant seconds before the rudder became effective and allowed me to slip my toes off the brake pedals — positioned perfectly for me, thank you very much, due to a wide range of fore-and-aft adjustment.
With the boost pump on, one notch of the electric flaps and holding the brakes until the engine hit redline, we sailed easily into the blue in defiance of the 90-degree temperature, 70-percent humidity, and our 2,200-pound operating weight.
Other flyers, the company demo pilots warned me, tended to over-rotate on takeoff, but for me, the same trick I use on my Comanche worked like a charm: Add a touch more nose-up trim than needed to help you break the nose gear free and let the airplane tell you it's time to raise the nose. As the nose comes up, hold the pitch angle, trim for best-rate climb speed and away you go — without dragging the tail.
Holding the heading straight on 090 degrees held little challenge, thanks to the generous control authority designed into the Star. The plane made it look and feel easy, as we climbed at 900 feet per minute and sailed an easy 500 feet above the departure end of the runway — against winds that varied from between 140 degrees and 160 degrees while gusting from 10 knots to 18. With the patterns of Plant City and Lakeland, to the east, nearly overlapped, clearing the runway end was my cue to turn right and get well south of both fields and out to where the real fun could begin.
Airwork was a piece of cake. Lifting my toes off the rudder pedals allowed the Star to respond naturally to my 15-degree bank and the skid ball settled easily toward the center — at least, as much as it could settle in the continuous light chop during our climb past the cloud base. Once in the smooth air above the widely-scattered cumulus, the great roll-yaw coupling of the Star became abundantly evident. The ailerons' differential design — the upward movement of the inside aileron exceeds the downward movement of the outside surface — eliminates most, if not all, adverse yaw. Yet with its wide 39.4-foot span and high-aspect-ratio wing (only 145 square feet) typical of all Diamond products, the Star looks the perfect candidate for adverse yaw: when the nose initially wants to go the opposite direction of the roll. The Star's combination of three degrees of dihedral and differential ailerons works well at most bank angles a pilot will ever see in normal flight. You practically could forget what the rudder pedals are for in flight.
Banking beyond 15 degrees through a bit more than 30 needed virtually no help from the rudder to keep the ball centered. Stopping a bank at the desired angle also took little effort and the response came crisply and easily, thanks to the ailerons' wide span. Even at the steeper angles — which command ever-higher pitch inputs and power levels for level flight — the control stick remains tactile and firm, giving feedback that made the steepest turns easier than in most machines in its class. And despite its wingspan, the Star responded quickly to roll-reverse maneuvering, going from 45 to 45 quickly and commandingly.
Based on these turns and banks, I can conclude that learning to handle the Star should present no serious challenge to student aviator or seasoned veteran alike. Overall, the crisp handling and enemy of easy maneuvering — stability — blend well enough to make the Star a worthy instrument trainer, instrument-flying or cross-country platform.
Similarly, the Star's low-speed handling seems to have received the same level of attention by Diamond's engineers. Its docile stall characteristics made me verbally ask, "That's it?" With the stall warning at full tilt, the Star simply declined to fully break into a nose-dropping stall, instead sort of mushing along, the nose rising and falling gently — almost as if a canard surface controlled pitch instead of a conventional T-tail.
Flight schools should love it even more than the capable Katana as a primary trainer because of the Star's combination of pleasant, predictable handling and its potential to take students beyond primary and into instrument work. And then there's the roomy, comfy rear seats the DA20 lacks — regardless of its powerplant — that give the Star true family-travel potential.
Few Fixed-Gear Four-Seaters Can Match This 180-Horse Bird
Stand aside, Skyhawk SP, move over Archer III, watch out Tiger — and beware Skylane. The DA40 misses nothing that I can think of for the first-time buyer or step-up pilot moving into a grown-up bird from a two-seater. And tops among the Star's attributes is its startling speed: more than 140 knots during my turn in the bird on a hot, high-humidity day — with some of the finer drag-cutting touches of production models missing.
Think about it — more than 160 miles an hour on 180 horses that, thanks to the Star's LASAR ignition system, burns fuel more like a 160-horse aircraft. Not since the days of the old C-model Mooney M20 and the later 201 has one design managed so much velocity on so little horsepower — and, just as importantly — on so little fuel. Diamond's projected 147 knots on 9.1 gallons per hour of fuel converts to a whopping 18.6 statute miles per gallon, in still-air terms, of course. While that's a pre-certification projection, I see no reason the production Stars can't make that number.
At that level of efficiency, the Star's standard 41-gallon fuel supply translates into 600 nautical miles, with a 45-minute reserve. And with a 992-pound useful load, that 246 pounds of fuel means the Star can carry 746 pounds of payload with full fuel, which is equal to four FAA-standard, 170-pound adults plus 66 pounds for bags and a few charts. If flying four-hour legs leaves you feeling like a slacker, Diamond offers an option that ups the fuel to 52 gallons, worth another 1.3 hours of avgas and 191 nautical miles. Of course, cabin load will need to be traded off to use that additional capacity.
Credit for fuel consumption closer to a 160-horse airplane goes largely to Unison's LASAR digital-ignition system and the unit's full-authority timing control that varies the spark advance from zero to 41 degrees. And, at prices ranging from around $150,000 to about $230,000, some of the Star's competition match its duration, some its range — but generally on more fuel. Conversely, some competitors in its speed class cost more and fly slower, have shorter legs and use more fuel. Nothing comes to mind on the new airplane market that matches the Star in range, fuel efficiency and speed, together.
It's not even impossible to imagine the Star snagging a few buyers away from Cessna's finest family sedan, the 182S Skylane — a 140-knot bird on fuel consumption in the 13-to-14-gph range. First, the Skylane has more payload than the Star, but would cost more in fuel for the same trips. Aiding Diamond in making its case for the DA40 is more than a simple speed-versus-payload projection: There's also the day-to-day living costs, including higher, ongoing costs of care and feeding the Skylane's six-cylinder Lycoming — 50 percent more oil at each change, 50 percent more spark plugs, six-cylinder mags, etc. Of course, until Diamond expands its dealer and support network, some pilots will always opt for the larger outfit. And there's always the 180-horse Skyhawk SP, which gives up about 100 pounds and more than 20 knots to the DA40 — at a savings equal to the Star's price advantage against the 182S.
Finally, beyond the costs and payload differences is handling that rivals Cessna's best — the 206H Stationair — albeit not all of the large Cessna's mass-related resistance to the bumps. It simply can't happen where total weights differ so much, even with similar wing loadings.
Making Light Work in Heavy Conditions
Even with its high wing loading, the Star makes transitions to and from the runway easy exercises with little to worry even the novice, once adapted to the Star's preference for a light touch and its slight hesitation to slow down, of course. Which brings up something to remember in all three of the high-performance plastic airplanes AVweb flew for this four-part series: You have no option to throw out the wheels to fudge bad planning, bad timing or bad ATC requests. The sleek, drag-cheating landing gear of all three plastic planes is down-and-locked for all time. Still, the Star offers flaps and a constant-speed prop to aid in deceleration.
This was all brought back to me the hard way, since even though luck smiled on my landings, the fates didn't reward my descents and pattern arrivals with the same enthusiasm. With two aboard and arriving at Plant City a bit high, my usual 500 fpm descent rate for pattern altitude worked out a bit too little, too late. A go-around seemed to loom ahead — until the Star showed me how easily and predictably it slips toward a runway. With no tendency to wobble or accelerate, the Star let me aim for my spot comfortable in the knowledge that my airspeed wouldn't grow proportionally with my 1,200-fpm descent rate. When time came to round out and cheat ground effect, simply relaxing my crossed controls, smoothly and proportionally, headed both my speed and descent rate downhill.
My entire second approach worked out better, thanks to starting my descent a bit earlier, in recognition of the Star's airspeed in my setup for the descent. After starting down farther out, the Star responded nicely to the braking of a higher engine rpm and we decelerated below maximum flap extension speed without a problem. From that point on, managing descent with power let me get the Star close to and off the runway even sooner. The faster guys landing behind me seemed to appreciate the effort. In both cases, crossing the numbers at 55 knots, decelerating, gave me an arrival close to my target spot on the runway. The smooth, relaxed pitch-up flare put me firmly on the pavement, rolling slowly enough to make the turnoffs.
If the Star pilot needs to watch for anything, it's an urge to flare too soon and/or too aggressively. Blame that on two positive traits: A big windshield and a relatively low glareshield. The combination gave me a view that looked closer and faster than my intentions. Holding the nose steady as our speed declined and the airplane and its shadow converged kept me from popping up a few feet in a premature flare — as well as avoiding a bad case of the ground-effect follies of arriving too fast and too flat. Instead of watching hundreds of feet of runway sail beneath me, the Star settled well — once and for good — on each landing. And I had worried that the beefy spring gear and tall windows would throw off my timing. No problem.
Which brings up something else worth noting about the newest Diamond: visibility. Of the three composite birds sampled for this series, the Star's tall windows and low panel, low window bases and slim frames give every occupant a great view of the outside world. And the position of the front seats even affords occupants more ground view than most birds, thanks to the wing's placement, almost even with where your posterior plants.
Diamonds and Rust: Maintenance and Upkeep Advantages Abound
Finally, the question: How will it hold up over time? We, as a community of aviators, designers, engineers and maintenance people, know, understand and trust metal in airframes, be it steel tubing in a cloth-covered bush plane, or in the sheet and stamped aluminum used in everything from bombers to business jets.
Composites still await a following among purchasers of store-bought airplanes and the would-be followers still need to be convinced. Compelling evidence already exists in the Beech Starship and Diamond's own Katana series, not to mention the hundreds of SR20s Cirrus has already sold, both in the durability and reparability of carbon-fiber-and-honeycomb-sandwich structures. The quick takers will provide the proof to the wait-and-see crowd, probably sooner rather than later.
Still, many of us fly aluminum airplanes made by people who, hopefully, corrosion-proofed every part before assembly. Resistance to corrosion runs highest in these metal birds so treated. But the years still pass and weak spots continue to emerge, demanding attention. Need more convincing on this advantage of a "plastic plane"? Look at the AD list of your favorite bird and count how many exist because of the corrosion and fatigue to which aluminum and steel are prone. Fatigue is always a concern where structures must flex and bend the way airplanes must flex and bend; but what it takes to fatigue composite panels would fail many metal structures. And only metal fittings, joints and fasteners present potential corrosion concerns for composite-airplane owners of the future. That means, on the Diamond Star, the engine mount, the engine and exhaust system, hinges, bolts, cables and sundry fasteners — but none of the airframe itself. Carbon composites just don't rust.
Fathoming the unknown and answering the question, "Will plastics hold up?" bring us full-circle back to our initial observations of how the prototype plane suffered through its testing and abuse under the BETA program. Built and tested to fail-safe standards should help sway some prospects. Over time, after what's unknown today has a chance to emerge, many others will worry less about the mysteries of composite airplanes.
In the meantime, worries about corroded spars, skins, bulkheads and stringers shouldn't be among the Star's problems.
The Bottom-Line View: Deliveries Can't Start Soon Enough
It's a pity that the Star won't be available in quantities until sometime after the first of the year [NOTE: At this writing, Diamond has not yet received FAA certification of the DA40, although the approval is expected very soon. -Ed.] Given its unusual configuration of front- and back-seat doors, its delightful handling qualities and sedan-level comfort, it's also a pity that it's not a bit less expensive — unless you make airplanes for a competitor. The fact is, some will view the DA40 as a bit too much to get a bit too little. But those same arguments arose when the Katana first hit the market, and its limitations — two seats, VFR-only — didn't prevent it from becoming a success.
My instinct is that the Star will appeal to enough people to make getting one problematic in another year, when all the certification and production start-up chores are done and the assembly line is rolling. That assumes Diamond will work its way out of some in-house problems in management and finances.
And anywhere a product of this potential exists, there usually also exist people who won't let it die. With its blend of speed, efficiency, comfort and utility, the Star is likely to survive — and perhaps succeed where others failed.
The line is already forming, too, so delay only lengthens the waiting list. And aviation's already waited too long for the composites revolution to unfold en mass.
This AVweb Pilot Report on the Diamond DA40 Star is the first of a four-part series on three new-production, all-composite IFR single-engine airplanes. In addition to the Star, AVweb has flown the Cirrus SR20 and the Lancair Columbia 300. AVweb will publish the articles on the other airplanes two weeks apart, then conclude this series with a wrap-up piece another two weeks later. Stay tuned!