Diamonds Star

A slick, sweet-handling cruiser with decent payload. But we pine for another 10 knots of cruise speed.

By now, Diamond Aircraft is best known for its sporty little composite trainer, the Katana. Although it might not have taken the world by storm since its introduction eight years ago-yes, its been that long-you see plenty of Katanas on ramps here and there.

Yet to tour the Diamond plant in London, Ontario, you could almost conclude that the Katana is an airplane of the past. Indeed, its no longer coming off the assembly line, with the current iteration of two-seaters called the Eclipse and the Evolution. (We suspect, however, that any two-seater Diamond makes will always be viewed by ramp dwellers as Katanas.)

These days-to a degree that surprised us-the London plant is given over mostly to production of the new four-place DA40 Star, which was certified in the U.S. barely a year ago but, according to Diamond, is enjoying brisk demand.

Between Europe and the U.S., Diamond has delivered nearly 100 DA40s and is ramping up to a production rate of about eight a month.

Do or Die
When Diamond first revealed the Star project four years ago, it appeared to be a logical successor to the two-place DA20 Katana. At the time, we didnt realize how important the Star would turn out to be, since Katana sales have trailed off somewhat, indicating that long-term, the market can absorb only so many two-place trainers.

Indeed, the Katana of old is no longer in production. It began life with an 80 HP Rotax, a powerplant that proved anemic in hot weather. Diamond completed two new engine projects for the trainer, fitting it with a Continental 125 HP IO-240 and a larger Rotax, the 912S.

The Continental version became the C1 Katana which has recently evolved into two additional derivative models, the C1 Evolution and the C1 Eclipse. The Evolution is what the Katana used to be, an entry-level trainer model with basic avionics and a base price of $123,900.

The C1 Eclipse is a step-up model featuring better basic avionics-a Garmin 430-and the option to add more, including a Garmin 420, an autopilot and an HSI. The basic Eclipse lists for $139,990; fully loaded it sells for a salty $172,350 or very close to the base price of its four-place sibling, the DA40.

Just to keep things straight, there’s one more version of the Katana still being offered as a refurbished product. The old Katana A1, with its 80-HP Rotax, can be re-fitted with a 100 HP Rotax 912S.

Diamonds president, Peter Maurer, told us the company has found many takers for this model, especially in Europe. All new production two-place aircraft are equipped with the Continental IO-240, which appears to be giving good service thus far.

And that leads to the DA40 Star, which has much in common with the Katana but is still a clean-sheet airplane. Two years ago, we flew a pre-production version of the Star and since then, the aircraft has been refined somewhat but is essentially unchanged.

A Big Katana
Overall, the Star has more in common with the Katana than not, of course. Its a substantially larger airplane but still not big. At a distance, you have to look carefully to tell the two apart; the tipoff is the left-side rear entry door and rear windows. The two airplanes share a similar wing section and planform design but the Stars is 3.6 feet longer, at 39.4 feet, meaning it will be a tight squeeze in a standard T-hangar if it fits at all, something which some would-be owners have balked at. On the other hand, the airplane needs that much wing to deliver the kind of efficiency Diamond wanted.

Like the Katana/Evolution/Eclipse, the Star is made entirely in London using a wet lay-up composite process. The wings are layed-up in vacuum jigs as two shells, then bonded together once the critical innards have been installed. Similarly, the fuselage is made in halves, with a long bond line to join them. Both are cured in a low-temperature oven.

Unlike the Katana, however, the Stars center is a separate wing box section, with a massive composite carry-through that also contains much of the electrical and control hardware. This was done to make cabin room for the rear seat passengers.

Even though its larger, the Star is still a very simple airplane, buildwise. Once the fuse and wing sections are made, the airplane is put up on its wheels and moved down the line-wingless-for completion all the way to avionics installation. The panel is wired and plopped into the airplane toward the end of the production line.

The basic control circuitry-rods and tubes for the ailerons, flaps and elevator, cables for the rudder-are layed in and then joined up at the end of the line, when the wings go on. The command flight control is a center stick rather than a side controller, something that sets the Star apart from its plastic brethren.

The fuel system consists of two aluminum tanks slid into open bays in each wing. These 20.5 gallon tanks can be removed, if necessary, by simply de-winging the airplane, a job thats not as big a deal as it sounds. After all, Diamond evolved from a company that built gliders. The wings are massively built, with a pair of carbon fiber spars each one of which alone is rated for predicted loads. The fuel tanks snuggle between these spars, we’ll protected from crash forces.

We could dismiss the Stars electrical system as standard stuff, except its anything but. The airplane is all electric; no vacuum pump, period. Its a 28-volt system with a single belt-driven 70-amp alternator wired to both a full-use bus and an essential bus for back-up.

Should the alternator fail, the aircraft battery can run basic avionics through the essential bus for 30 minutes. For additional back-up, there’s a pack of off-the-shelf AA cells behind the panel, which can be brought online with an emergency switch on the panel.

This will run the electric attitude gyro and a cabin light for up to 1 1/2 hours, which ought to be plenty of time to find terra firma after an electrical failure.

Avionics, Instruments
One reason the Katana never took off as a personal-use airplane is that it was never IFR certified. Neither are the Evolution nor the Eclipse but the Star is intended as a serious IFR machine, or at least as serious as a 180-HP airplane without turbocharging or de-icing can be.

That meant two things; decent avionics and lightning protection. The lightning protection comes in the form of metal grid work bonded into the wings and fuselage and tied together with bonding straps and surprisingly heavy metal conduits for wing wiring and other critical electrics. Other than pitot heat, the airplane has no ice protection and none is planned.

For standard avionics, the Star has a Garmin 340 audio panel, a GNS430 and a GTX 327 transponder but thats hardly the stuff of serious IFR. So most buyers are wisely opting for the deluxe Garmin package, which adds an additional 430 to the panel.

We like the fact that Diamond doesnt beat up its customers on the price of additional avionics, as most manufacturers seem to do. With the standard avionics package, for instance, the base price is $181,900. Add the second 430 and it increases to $189,900, a price Delta of $8000 and about what youd spend for a 430 on the open market. The demonstrator/rental Star we flew had a Garmin 530, a $6490 option over the base price.

Other avionics options include a WX-500 remote Stormscope ($7595) and a Bendix/King KAP 140 two-axis autopilot with pre-select and altitude hold ($24,900). Most buyers, says Diamond, are opting for the full boat so typical invoices on a new Star are in the $225,000 range, making the airplane a competitor with the Cirrus SR20 and the Piper Archer in price, if not performance.

One thing the Star lacks is excess panel space. The far right stack is occupied by a Vision Microsystems VM 1000 multi-function display which carries all of the engine instrumentation. The VM 1000 has been found in homebuilts for years and at first blush, we didnt think it appropriate for a new production airplane of the Stars quality.

Weve changed our mind, however. The VM 1000 nicely displays manifold pressure, RPM and all of the critical engine parameters and incorporates a fuel computer and a digital engine monitor, both of which we think should be standard in any new aircraft.

It also has an engine data recorder limited to the previous flight only. Fuel quantity is displayed digitally and in electronic analog format on a round instrument below the VM 1000.

There’s an open round instrument hole to the right of the VM 1000 but little room for additional avionics. Thats no problem, perhaps, for buyers of new airplanes, but as the models age, owners may want to upgrade with newer boxes which may prove to be a tight fit.

When Diamond proposed the Star, there was no small angst over whether buyers would accept a four-place airplane with the sort of hinged canopy normally found on sport trainers and aerobats. But structurally, the company had little choice but to go with this design, in order to meet weight requirements and to make the airplane a logical iteration of the Katana.

But unlike the Katana, whose canopy pops up from the rear, the Stars hinges from the front on a pair of beefy spring-loaded tubes which double as handholds for entering the airplane. The canopy is relatively easy to manipulate and you enter the aircraft from forward of the wing rather than from behind it. There’s a step for this purpose just below the leading edge.

As weve noted before, the airplane is somewhat awkward to enter and exit. It takes a practiced swing of the legs and butt to get it right and some dancing on the seat leather seems inevitable. The rear seats are accessed through a generous hatch on the left side of the fuselage and although this strikes many as an odd arrangement, we think it works quite well, allowing easier access to the backseats that does the Cirrus SR20/22 or any of the Cessnas.

But watch it. Standing on the wing for entry, the edge of the door bashed us in the forehead going in and on the back of the neck coming out. you’ll have to pay attention to avoid being tattooed by the latch mechanism.

Speaking of which, the releases for both the canopy and rear hatch are we’ll designed, with a door unlatch warning light for the canopy. The rear hatch has an easy-to-operate double latch mechanism that should obviate in-flight opening, which is something you don’t want to think about. Were not sure if the hatch would depart the airplane or not but suspect that it probably would.

As an overall design feature, its our view that doors that don’t trail harmlessly on opening are a bad design idea, as are doors or canopies that can jam shut in the event of a flip over. The Star has both and, bluntly, we think thats an unfortunate compromise in terms of overall safety.

Our review of NTSB accident records finds an alarming number of roll overs, especially during emergency landing attempts. We don’t find many instances of occupants trapped as a result of these rollovers simply because there arent many aircraft out there with canopies and gull-wing doors. Yet. We hope were wrong about what could become a disturbing accident trend.

In fairness, the Katana, with its rear-opening canopy, has posted an exceptional safety record. Then again, its a trainer, not a go-places general-use airplane. To address this, the Star has a small crash hammer and an overhead release handle pops the hinges on the rear cabin door.

Once inside the airplane, the canopy provides fantastic visibility, especially forward. But on a hot day, you’ll pay for it. During taxi, the canopy can be cracked to allow a cooling breeze; not too bad.

In flight, the canopys shaded overhead portion helps keep your noggin from frying but we found that for the front seat occupants, the ventilation is just barely adequate when flying into the sun.

A pair of automotive-style grill vents and overhead eyeballs spew air into the cabin but there’s no cooling to spare and the vents are quite noisy. In fact, thanks to all that glass, the overall cabin noise is high; you’ll want ANR headsets.

Down sun, in the shade of the canopys frosted overhead section, the airplane is dramatically cooler. Rear seat passengers fare better; a pair of massive vents provide lots of air, even when idling on the ground.

We would rate seat comfort as good but not great. In keeping with Diamonds simple, fast-build philosophy, the seats neither recline nor adjust; you move the rudders forward and aft to accommodate leg length.

Leg room is adequate but not generous; shoulder room is excellent, however, with the front seaters separated by a console that contains the throttle, fuel switch and trim wheel. In the intervening months since we flew the prototype, knee room has been improved by modifying the instrument panel and placing the circuit breakers on a recessed sub-panel. The breakers are still easy to access.

The rear cabin is smallish but comfortable, except for the aforementioned lack of seat recline. Legroom is tight but Diamond cleverly hollowed out the area under the front seats so passengers have a place to put their feet.

Performance, Payload
On the ground, the Stars sleek, seamless surfaces suggest speed but, alas, looks can be deceiving. Although the airplane is no slug, its no Bendix racer, either. The companys marketing boilerplate touts 145 knots on 9. 5 GPH but if the POH is to be believed, it will take nearly 85 percent power at sea level to fly that fast.

Realistically, at 65 percent power, a more sedate 135 to 138 knots is what to expect from the Star at a fuel flow of 9.5 to 9.8 GPH, which is best power. We recorded a bit less than that on a recent test flight but managed 141 knots on a previous test flight at 67 percent power.

Thats somewhat anemic compared to the Cirrus SR20 or Lancair Columbia, which both have more horsepower. But it blows away the New Piper Archer and Cessna 172, which share variants of the same Lycoming O-360. The Archer has a carbureted O-360, while the Cessna 172 and Star have fuel-injected IO-360s.

With three people aboard and some 150 pounds under gross, the Star does impress in two ways: it has excellent short-field takeoff capability and posts a healthy climb rate for such a low-powered aircraft. According to the POH, at gross weight on a standard day with no wind, the Star is off in 1200 feet. At low weights, with a modest wind, its off in a little more than half that.

This performance seems to accrue for several reasons. At 2535 pounds gross, the Star is light, with a power loading of 14 pounds per HP and a wing loading of 17.4 pounds per square foot.

It has a three-bladed MT composite prop, a design choice thats unusual for a low-powered aircraft. This helps with climb performance but the prop hurts cruise performance. A two-blade prop, which is under consideration, may address this.

Another 10 or 20 knots of cruise speed would make the Star a real head turner and that may just happen. Diamond is considering other gasoline engine options-they wont say which, yet-and have already announced a diesel variant using the Thielart TAE 125, a turbonormalized design of 135 HP. (See page 10 for more detail on this.)

If the TAE 125 can get the Star into the low teens, 150 to 160 knots seems possible on a fuel flow half or two-thirds what the Lycoming requires. If that happens, the Star will become a very different airplane; a relatively fast, long-distance high-altitude cruiser.

As currently configured, the Star is best thought of as a three-place airplane. With useful loads of about 850 pounds, the Star can haul 600 pounds with full fuel; three people and baggage. And not much baggage, either.

The baggage compartment is quite shallow and accessible only from the inside of the rear cabin, by tilting the rear seats forward. Since we last examined the Star, Diamond has added a baggage extension area that consists of a long carbon fiber tube extending into the tailcone. That helps with volume but isn’t nearly as convenient as a larger baggage compartment would be.

Off loading fuel to improve payload is always an option, of course, but because the Star has only 40 gallons to begin with, the range hit to carry a fourth person is significant. With its better efficiency, the Thielart diesel may solve this quandary.

The Stars weight-and-balance envelope is relatively benign, narrowing a bit towards the gross weight end. It tends toward forward rather than aft CG, which we think is a good thing.

With its center stick, the Star is a sweet, easy-to-fly airplane thats perfect as either a basic trainer or a mid-range cruiser. It has a brisk roll rate and is light in both pitch and roll. We find the rudder circuitry somewhat stiff, perhaps because the pedals are small and relatively constricted; pilots with big feet have to consciously position their toes to avoid the brakes when they really want rudder.

Ground steering is via brakes only and is quite precise with a tiny turning radius. Turns work best if brake pressure is anticipated ahead of needing it and tight turns have to made with the aircraft rolling, not from a dead stop.

Diamonds Jeff Owen pointed out that the center stick seems to want to neutralize itself near the aft travel limit but trimming correctly keeps it comfortably centered. The stick has a pickle switch for electric trim and there’s also a trim wheel on the console.

The airplane isn’t particularly trim hungry, however, and out-of-trim forces are easily dealt with because of the sticks considerable leverage. Flaps have little or no effect on trim condition.

Slow flight and stalls are childs play. In fact, Diamonds Maurer makes the point that hands off with full aft trim and no power, the Stars descent rate is a gentle 700 FPM compared to the Cirrus SR20s 1300 FPM under its ballistic parachute. Of course, the Stars parachute mode would have greater forward speed than the Cirrus.

Landing a Star couldnt be much easier, although the sight picture over the nose tends to encourage high flares. We found that 60 to 65-knots over the numbers resulted in a reliably firm touchdown. Higher speeds will yield noticeable float.

In visiting Diamond, were left with the strong impression that this is a company that knows what its doing. It clearly took what it learned from the Katana-good and bad-and applied it to the Star. Its sales and marketing goals are realistic and with its diesel, it has a sensible grasp of the future world market.

We see the Star as a credible if not exceptional step-up cruiser from the Katana or any modest two-place aircraft. At a typical price of $225,000, we think its a better value than the New Piper Archer or the Cessna 172SP. The Star carries only a little less but is faster. The Star fares less we’ll against the Cirrus SR20, which is considerably faster and carries more for the same price.

But the Star is a more interesting airplane to fly, in our view. We vastly prefer the center stick and the exceptional cockpit visibility. What the Star really needs is another 20 knots and Diamond appears to be working on that.

Also With This Article
Click here to view “Checklist.”
Click here to view “The New Diamond: Sales Not Leases.”
Click here to view “How the Star Stacks Up.”