Diamond in the sky

Against this background, Diamond Aircraft is proving something of a standout, and the latest version of its DA40 four-seat offering, the XLS, is causing quite a stir.

In the Family

Diamond Aircraft has been sneaking up on the Australian market without a great deal of fuss before now, although that is now changing with Hawker Pacific recently taking over as the local representative.

When asked to “follow the Diamond on final”, most pilots could be forgiven for not being entirely sure of what they were looking for. Yet the facts belie the aircraft’s relative anonymity.

Based in Austria but with a significant manufacturing presence in Canada, Diamond has been building composite aeroplanes for over 25 years. In that time, it has grown to offer a range of single and twin engined aircraft so that by 2007 its fleet was second only to Cessna in the new piston market under 200hp (150kW).

Part of the attraction of the Diamond range is the family philosophy. From the two-seat DA20, through the four-seat DA40 and onto the twin engine DA42, there is a high degree of commonality that provides for smooth transitional training from ab initio to multi-engine IFR. The Diamond family is further expanding with the five-seat, high performance DA50 piston single, and the single Williams FJ44 turbofan powered D-Jet.

The DA40 is a key member of the Diamond family, filling the ever popular four-seat role as both a private touring aircraft and an advanced trainer – roles that have been dominated by types like the Piper Archer and Cessna 172 since the 1960s. Announced in 1997, the DA40 was first delivered in 2000 and today over 1000 have been built, with Diamond’s Austrian plant building Thielert jet fuel burning diesel engined variants (before Thielert’s bankruptcy), and Canada responsible for production of Lycoming IO-360 models.

In 2006, Diamond fitted the Lycoming DA40 with its most popular options as standard equipment and labelled it the XL.

The following year the range was further defined with the base model CS and top of the line XLS.

Brilliant Cut

The first thing that strikes you on approaching the DA40 XLS is that its designers have taken the bold step and ventured down the new road. This is not the reworking of an old formula, it is a blueprint for what lies ahead. The XLS is a thoroughly modern light aircraft that brings together a combination of new materials, design, avionics and engine technology.

Immediately, the aeroplane’s appearance announces its heritage where Diamond hasbeen at the forefront of high aspect ratio motor glider technology for years. With its composite construction the finish is slick, with the rows of rivet heads replaced by clean lines and a high gloss finish.

Sitting on the Bankstown ramp upon its spatted fixed tricycle undercarriage, the DA40’s minimalist appearance is accented by winglets, a strake under the aft fuselage, and a T-tail perched above a substantial fin and rudder. The three bladed constant speed composite propeller sits well clear of the tarmac and is driven by a 180hp (134kW) Lycoming IO-360-M1A engine.

Additionally, the XLS is fitted with the ‘Power Flow’ tuned exhaust system. In the confined constraints of aircraft cowlings, exhaust systems can struggle to efficiently ‘dump’ exhaust gases overboard. Consequently, a portion of these gases can remain in the cylinders impeding the effectiveness of the next engine stroke. The ‘Power Flow’ system seeks to ensure efficient exhausting of the used gases and under dyno testing has proven an increase in efficiency of 20hp (15kW) and around 7kt in the cruise.

Along with engine efficiency and aesthetics, aerodynamics have obviously been a primary focus of the design team at Diamond.

While the constant foes of weight and drag will never be entirely defeated, the XLS has pinned them down to a fairly small corner of the battlefield. The days of merely putting more horsepower up front to drag the same airframe through the air are gone. By the time the increased weight and fuel burn are factored in, the benefits look rather paltry if the aerodynamics are not attended to.

The modern age is about efficiency, and composite materials offer strength at a fraction of the weight. Furthermore, as the strength is integral to the composite structure, it doesn’t require extensive framework underpinning a metal skin. This is obvious when observing the narrowing of the aft fuselage of modern composite aircraft and gliders. Interestingly, against comparable 180hp (134kW) four-seat metal aeroplanes, the DA40 has around a 20kt advantage, or burns seven litres per hour less at the same speed.

Beneath these smooth lines there is an even more crucial matter at stake – safety.

Critical structures and joints, including control surface hinges, are designed such that the complete failure of a single element will still permit the aircraft to fly safely. Additionally, the DA40 possesses dual redundant spars in the wings and tail surfaces, and dual connections for all critical joints. Within the wing, the fuel cells sit between the spars giving further protection to the tanks in the case of any impact. Linking this fuel system throughout the entire airframe are stainless steel braided fuel lines, which are far stronger than traditional fuel lines and offer a degree of flexibility.

Beyond its looks, the DA40 is all about safety and efficiency.

Welcome Aboard

The time had now come to fly the aircraft and see whether the smooth lines, design and hype actually translate into a good aeroplane. As I boarded the XLS it became apparent that practicality was another area Diamond had considered.

Climbing onto the front of the wing, access to the cockpit is easily achieved by stepping down into the aircraft, ably assisted by strong, obvious handles to save the interior from misplaced hands.

A separate door on the left hand side is provided for the rear seat passengers, doing away with the traditional awkward access via the main door of most four-seaters. Behind the aft seats is a spacious baggage compartment that hasan additional storage section beneath its floor. This concealed area serves ideally as stowage for the necessary aircraft items of tow bar, oil, covers, etc.

Once seated there is a sense of space afforded by both generous headroom and the wraparound windscreen without any supporting pillars. The XLS is equipped with the ‘Platinum’ interior which boasts very comfortable high back leather seats for all on board, but the feel of a superior finish extends well beyond the seats. Integrated into the leading edge of the front seats is a ‘control stick’ whose leather skirt gives the feel of a sports car gear shift. The centre console, latches and selectors feature a quality brushed aluminium finish.

Yet beyond this finish, there is a well thought out approach to safety. While car manufacturers have been continually working on cabin safety for decades, it has been relatively overlooked in general aviation.

But the DA40 cabin is effectively housed within a structurally sound ‘safety capsule’, the seats are integral to the airframe and built to withstand 26G, while the seatbelts have their own airbags. Additionally, critical items such the central fuel selector and door latches are lightweight, but substantial and logically colour coded red. Yes, there are ergonomics in this light aircraft!

At the Ready

Having strapped into my seat belt and adjusted the rudder pedals with an electric toggle switch, I ready myself for engine start, but all I have before me are some basic flight instruments and two large blank screens. And then the Garmin G1000 comes to life! To my right the multifunction display (MFD) presents an abbreviated set of engine instruments and a means of entering today’s flightplan. Seemingly any combination of flight information, engine parameters, map displays, charts and weather radar can be selected across the MFD and the primary flight display (PFD) in front of me on two sizeable screens. Today I’m flying with Hawker Pacific’s Tony Norris, who flies Boeing 777s in his ‘free’ time. We look at each other and share a joke about how this technology surpasses the equipment in many jet airliners.

Putting my fascination with the bright lights to one side, the aircraft is relatively straightforward to start. It is a lean start, following about five seconds of prime with the throttle and mixture forward, reminiscent of starting a Piper Chieftain.

(The mixture is also equipped with a useful safety catch. ) After start, we taxi off the ramp, steering by the DA40’s castoring nosewheel. Without doubt, this is the best castoring nosewheel I have encountered. Tight turns are normally achieved with a touch of power and a nip of brake, much in the manner of a taildragger. Very little effort is required and the DA40’s ground steering is comparable to a direct linkage nosewheel in terms of feel and response.

One major consideration is that a close eye does need to be kept on the wingtips when taxiing by virtue of the 12m span.

Pulling into the runup bay we find ourselves beside a very tired Cessna 152 – chalky paint, numerous run marks and oil smears on the cowling and crazing on the windscreen – a great contrast to our brand new and high tech Diamond.

The preflight sequence checklists can be pulled up on one of the Garmin screens, but you always have a paper copy handy in the flight manual as well. While confirming the controls are full and free in movement, it becomes apparent that despite being a lightweight aeroplane, the DA40 has a very sound feel to it. I have flown the Grob trainer in years gone by, where its lightweight aerodynamics carried over into a lightweight ‘feel’, from the ground steering to the control column. This is certainly not the case with the Diamond.

Taking Flight

Ready at the holding point, the traffic advisory system visually and audibly warns of the aircraft slipping down final toward us, while the Synthetic Vision Technology (SVT) presents a computer generated image of the runway threshold ahead. The main PFD features a speed tape, altitude tape, VSI, HSI and attitude indicator.

Adjacent to the speed tape are reminders of rotate, best angle, best rate and glide speeds, all of which become active ‘bugs’ when airborne.

Lined up with the first stage of flap selected we are given takeoff clearance.

Power is smoothly increased to full and the acceleration of the DA40 is impressive, with an acceptable amount of right rudder required to maintain the centreline.

In a minimum of time and about 300m, we are at 60kt and beginning to rotate before establishing an initial climb speed of 70kt. The aircraft takes to the skies with a climb rate in excess of 1000ft/ min and flaps are retracted before the Diamond accelerates through the limit speed of 108kt.

On climb, the power reduction is made to 2400rpm with the throttle remaining full, giving an over-square power setting.

Initially levelling out, 75 per cent cruise power was set and it is easy to see why this aircraft achieves 150kt. It is particularly impressive when one considers an Arrow IV with a larger engine and retractable undercarriage is working to achieve those numbers. Throttling back to 55 per cent power the aircraft indicates around 130kt and burns around 28 litres per hour.

The view from the aircraft is panoramic and affords a good lookout, enhanced by the pilot’s position forward of the wing.

The ventilation is provided by large fisheye vents either side of the panel and the noiselevels are very acceptable. In fact, it may be a by-product of the ‘Power Flow’ system but from within the cockpit the Lycoming has a deeper, throatier pitch more indicative of a six cylinder engine.

Throughout a series of manoeuvres, including a steep turn, the controls were very well balanced and gave a solid, proportionate feel for the control input. It is responsive and belies the lightweight nature of the aeroplane. Detractors of so-called ‘plastic aeroplanes’ should fly the DA40 to see just how solidly it handles. At altitude, low speed handing was also very good. In the stall, the aircraft is docile. It provides the textbook warning signs of an impending stall, before simply developing a sink rate and a mild buffet with no tendency to drop a wing.

Interestingly, the ailerons were still effective when the aircraft was in a fully developed stall, though more sensitive to inputs.

Following the upper airwork, we observed the Synthetic Vision Technology (SVT) and its amazing representation of the world outside. As an added safety feature, the displayed terrain becomes yellow as the aircraft descends into a cautionary zone, before turning red at the dangerous end of the spectrum. The system provides a tremendous aid to situational awareness when used in conjunction with the traffic advisory system, map display and let’s not forget looking out the window. In a particularly advanced aspect of the system we coupled the autopilot to fly a RNAV approach using the SVT’s Pathways. These are a series of ‘flying rectangles’ represented on the screen and the aircraft flies down through them along the approach path as if it were flying through a tunnel in space. So impressive was the display that I half expected to look out the windscreen and see the rectangles floating in the real world!

Coming Home

Breaking off the approach, we flew the aircraft in the circuit before ending the flight.

By virtue of its clean lines, a degree of anticipation is required to decelerate the DA40 on entering the circuit. Like many higher performance aircraft, it will tend to go down OR slow down, but not generally both at once. As such, some planning is required – which is a worthwhile training quality for students moving to more advanced types.

Once slowed down and below flap speed, the aircraft retains its very stable feel and is easy to fly in the circuit. Conventional power settings of around 20in on downwind before reducing further on the base leg descent see the DA40 fly a 75kt base and 70kt final with ease. It has no vices on approach and flares just as you anticipate it should, resulting in very acceptable landings from the first attempt with the use of minimal runway.

A True Diamond

I was impressed by the DA40 XLS. The Diamond philosophy has produced a range of aircraft that offer the student and personal pilot the latest in comfort, safety and technology in an aeroplane of genuine performance.

The DA40 XLS offers owners and organisations an aircraft that is designed with its eyes set firmly on the future. In this era of tiring airframes and fading paint afflicting much of the GA fleet, the DA40 XLS is undoubtedly a Diamond in the rough.

DA40 XLS

Technical specifications
Powerplant
One 180hp (134kW) Lycoming
IO‑360-M1A. Constant speed three
blade MT composite propeller.
Performance
(Manufacturer’s stated)
Max speed 157kt
Cruise speed @ 75% power 150kt
Stall speed full flaps 49KIAS
Range at 75% power, 45min reserve
720nm
Range at 55% power, 45min reserve
785nm
Max operating altitude 16,400ft
SL rate of climb 1120ft/min
Weights
Max takeoff 1200kg
Useful load 390kg
Fuel 189 litres useable
Dimensions
Length 8.05m
Height 1.98m
Wingspan 12.05m
Wing area 13.5m2
Price
US$334,950
www.diamondaircraft.com