The Kinder, Simpler, MORE Affordable Diamond Four Seater (Part Three)

• Read Part One of This Test Flight Series

• Read Part Two Of This Test Flight Series
  

When last we left ANN's Jim Campbell and the poor guy from Diamond Aircraft who got conned into riding along with him (now undergoing intensive therapy that shows great promise), they were all lined at the end of Winter Haven, FL's Runway 11, ready to commit the unpardonable 'sin' of aviation.

And 'sin,' they did…

Firewalling the FP's O-360 produced modest acceleration (that improved significantly once we get a few knots under our belt and gave that prop a chance to get an air-bite) and moderate torquing, easily countered by what Diamond describes as an "enhanced" rudder. Light pressures (barely a few pounds) were all that was required and a slight stab of toe-brake kept things lined up well until about 20-30 knots when the rudder and vertical stab got a taste of the relative wind and were all that was needed from there on out. One notch of flap was used, and following my experience with previous generations of the DA40, I eased on a lot of aft stick pressure early in the ground roll, until the nosewheel lightened perceptibly. At that point, I started easing OFF the pitch to assume a deck angle near 10-12 degrees until liftoff… and then settled into a 65 knot attitude that produced a ready 1000 FPM at the start, with a fairly decent deck angle that needed to be lessened now and then to check the way ahead for interlopers (especially the B1-RD variant) intent on playing mid-air roulette off the departure end of RWY11. Cooling from the larger air vents on either side of the cabin is excellent… a necessity underneath that big beautiful canopy (literally, a virtually unrestricted window to the world below).

With about 600 pounds of payload (fuel and pax), and 80-85 degrees in the kind of sky that Florida tourist bureaus love to brag about; the FP was off and running in an easy 1200 feet. Initial P-Factor issues were easily countered with light to moderate rudder pressure, visibility over the nose was slightly restricted by the Vx climb I selected in order to check the FP's cooling prowess, and the delightful control harmonies I remembered from the constant speed-equipped DA40-180 were as good as ever. A climb to 5500 feet, taking 9 minutes from brake release to nose-over, yielded excellent temps that peaked at 358 degrees and started backing off by the time we reached the 4500 foot mark… in apparent sympathy with the lowered ambient temps at such lofty heights. For the busy flight school that does a lot of hot and heavy taxiing and climbing enroute to the day's lesson, the additional cooling in the FP would seem to be a good investment against premature engine melt-down.

The DA40-180-FP flies much like its CS cousin. The short throw control stick impresses one with little mechanical feedback and requires light to moderate pressures throughout the approved flight envelope. Of short stature, fingertip pressures can do most of the work, and produces a fairly agile roll response, complete with a noticeable adverse yaw and excellent pitch response. Aerodynamic feedback is well pronounced with a noticeable (and fairly linear) stick force gradient throughout the normal speed range of the aircraft, despite the fairly modest pressures inherent in this airplane. Pitch is particularly well defined in that it features a slightly higher stick load than roll, sports virtually no breakaway inhibitions (none of the mechanical persuasion... this thing is SMOOOOOTH), and conforms obediently to the speed range in use.

Rudder pressures are modest, as well, and produce a lightly separated response that will, with larger input, roll the aircraft sympathetically with the chosen input. The power of the rudder, though, is not to be underestimated… it has as much authority as you may possibly need and seems to have benefited nicely from some additional attention from Diamond's aerodynamic aces.  Coupled together and led slightly by rudder, the coordinated rolling response of the FP is agile, but not sensitive, and produces an obedient response at most any speed in the normal envelope... And then some.

Stability and control issues with the FP are a delight. The static pitch stability of this trainer bird is exceptionally well defined and a look at its dynamic behavior reveals a pretty obedient bird. In 10 degree, stick-free displacement at cruise speeds and settings, the FP offers up a low frequency cycle of modest amplitude (diminishing on the order of 50% per cycle) that is pretty well damped out in about three excursions. Short period pitch behavior is nearly deadbeat with virtually no oscillatory belly-aching.

The roll/yaw scene is about as well defined… with exceptional spiral tendencies. The usual steady heading/attitude side-slip excursions saw obedient behavior in roll and yaw, upon release to the trimmed configuration. Dutch roll investigations were well damped in a few cycles and pretty much done in two. Sweet.

Pitching over at 5500 feet, we leaned the O-360 back a bit, watching the G1000 give us excellent feedback on each cylinder of the Lycoming four-banger. A 2500 RPM run yielded a fuel flow of slightly less than 10 GPH, and a power rating of a little over 75%. After settling on "the step," the FP showed an unerring ability to hold to a TAS of at least 135-137 knots… well within what one might expect with a slightly nose-heavy load at a
fairly inefficient altitude, in a bird boasting 140 kts for a top end cruise. 

Particularly laudable is the in-flight visibility of the FP (as well as the CS version of the DA40). Its sailplane heritage is evident in the exceptional visibility offered up by the bird and the surprisingly "nose-low" impression the airplane takes in cruise, not to mention the fact that the high-aspect ratio wings that muck up little of the lateral viz. If you can't see what's in your way in a DA40, it's time to order a seeing eye dog. For flight training, this is invaluable… and for just plain "flight-seeing," you'll get no complaints from your passengers… this is a very pretty way to fly.

To be continued...

(ANN will be publishing flight test data and research from our flights in the new Diamond DA40-180-FP, the new Cirrus SR22-G2 and the recently certificated Lancair Columbia 400 over the next several days… don't miss them!)

FMI: www.diamondair.com