Something Different

By lex, on March 28th, 2009

Well, the Cessna Cardinal in which I had hoped to drag the Biscuit through th’insubstantial air is still tango uniform, on account of the landing gear refusing to perform its duty and stow itself away when commanded. It being but a dawdling climber even when the wheels are in the well, and speed restricted with ‘em hanging in the breeze all regardless, the idea of flying her around stiff-legged does not cause the go-fer-it needle to budge from its lower limit.

And Cessna 172s, whatever else their manifest advantages, do not cause the heart to flutter after a time.

But there was that little Liberty sitting there upon the tarmac, all forlorn like. And the club does need 15 hours a month on the Hobbes to make the leasing of it worth the effort. And it does come with a stack of Garmin COM/NAV gear, with the 530 on top and the 430 below. With TCAS and all.

Something Different

Apart from its clean lines and modern cockpit, the plane’s real distinguishing feature is the two-channel, full authority digital engine control (FADEC), a first for a piston engine design. This allows for both simplicity and economy of operations, since there’s no mucking about with a primer or mixture control on deck, and the FADEC can meter fuel to the engine in flight much more efficiently than can a pilot since it senses the condition of each cylinder head as well as air density, temperature and flight condition. The FADEC allows the pilot who is paying for his own gas – rather than a club operator paying per “wet” hour on the Hobbes meter – to milk the airplane at up to 120 knots indicated at around 5.5 gallons per hour fuel flow – an automobile like 21 miles per gallon, with no stop lights or freeway hassle, depending on the winds. We never got high enough to lean the engine out to those numbers: At 3500 feet traveling up the coast we were limited to around 100 kts by the fixed pitch prop.

While improvements have been made to the initial design in follow-on iterations, our club Liberty remains unmodified, so weight and balance is a real concern. With the awesome grandeur that is Lex in the left seat, and a moderately nourished instructor pilot to his right, we were forced to load the aircraft 13 gallons short of the 28 gallon maximum capacity to remain within gross weight limits – a serious constraint for a non-solo cross-country flight. GPS and TCAS notwithstanding.

For reasons best known only to themselves, Liberty chose to place the brake actuators on levers on the center console. This does pretty much forestall any skidded tires on landing by overactive rudder operators, but it is deeply counter-intuitive to anyone who has several thousand hours doing it the other way. It comes to you in time, I’m sure, but your correspondent found bumping the throttle with the base of his thumb while manipulating the brakes with his first and second fingers a sore trial throughout ground operations. It really does seem like re-inventing the wheel. Apparently Liberty offers a conventional toe brake option in later models.

There’s a bit of a dance at the hold short to ensure that fuel boost pumps and both channels of the FADEC are operating within limits. FADEC Channel A runs off the primary power bus, which includes a battery and an engine-driven alternator. Should the main electrical power play the fool, a back up battery (FADEC B) promises to give you sixty minutes of uninterrupted engine time before the spinner stops entirely, leaving you to your ineluctable fate if you haven’t found a suitable place to put her down by then. The twin magnetos that are everywhere else standard in piston engine singles have their own failure modes, and time will tell if the market is ready for the same kind of electronic fuel control that most cars employ nowadays.

Once on the runway with the power up, the finger brakes become redundant since the rudder has full authority from the get go. Acceleration at seal level is not breathtaking, but a good ten knots below the published 55 kt “lighten the nose” speed the machine is more than ready to take to the air on 20 degrees of flaps. Your real climb begins one you’ve accelerated above 65 kts and can pull the flaps up. At 80-85 kts the Liberty earns an honest 700 feet or so per minute rate of climb on a pleasant day in Southern California.

Over the narrow speed band, the electronic elevator trim (there is no rudder or aileron trim) seems almost redundant. The airplane feels remarkably stable with neutral controls, and only very slight breakout forces engage surprisingly brisk roll rates and only marginally less nimble pitch responses. Turns are entered and exited with equal grace. The novice get the sense that the plane will be a solid IFR flyer, which will prove true at the end of the flight.

Turns at high and low speed are unobjectionable, with a bit more rudder required at slower speeds – and I mean slow, she stalls at under 40 kts – to keep the nose honest. Nose high power-on stalls happen well after the female voice warning system asks if you know what you’re doing, with a pretty good right wing break on stall entry. The challenge is not to overcontrol the recovery, as it turns out – simply ease the back stick out and you’re flying again. Power off stalls are, if anything, more benign.

The landing pattern at Ramona was a charm until the roundout. My first landing was no-flaps, flown at 75-80 kts throughout. With the runway made I eased power to idle and milked the nose to break the rate of descent. Which was when I noticed that, regardless of our proximity to maximum gross weight, that 40 kt band between approach and stall is quite a lot in a relatively slick airframe. I might have been ready to put her down in the first third of the runway, but the XL2 had some flying left to do. We hovered over the runway at highway speeds for what felt like an eternity before impatience got the best of me and a gentle porpoise – it’s my story – put her back on terra firma.

Twenty degrees of flaps slowed our approach to 70-75 knots, and she landed more gracefully than before, although we still spent a fair amount of time in the landing attitude with the runway flashing by beneath us. Thirty flaps made picking a landing spot easier, but required reconfiguring on the go. The flap indicator consists of three LEDs for zero, twenty and thirty flaps. Simpler than a mechanical indicator, and more reliable to be sure. But it’s a bit distracting staring at the lights waiting for the right indicator to illumininate while you’re trundling down the runway, and in any case they’re a little hard to see in bright sunlight.

Which brings me to visibility – it’s absolutely stunning for a low wing aircraft, a full 270 degrees of unobstructed horizontal view. I felt a little like I was flying a bubble-nosed helicopter. In a totally non-ghey way.

A crosswind departure to the south from Ramona to the ILS final at Montgomery. The Liberty flies a stable approach, and your correspondent did not disgrace himself under the IFR glasses. The final landing was in a moderate crosswind requiring a wing-down, top rudder approach. Under such circumstances, the no flap landing felt rushed and awkward, but it was well within “safe standards”, at least according to the instructor. The finger brakes brought the airplane to stop in short order.

The plane was simultaneously stable and manueverable, which is a neat trick. FADEC is hella cool. I love the cockpit – 48 inches from side to side – and the avionics are great for aircraft in the Liberty’s class. I’m not entirely in love with the finger brakes although I’m sure I’d get used to them in time. At the end of the day, the gross weight issue for early production aircraft would be a deal-breaker for me, at least insofar as concerns any plan to bear two passengers and modest baggage over a distance.

It was fun, though.

Back To The Index 

Leave a comment

Filed under Best of Neptunus Lex, by lex, Carroll "Lex" LeFon, Carroll LeFon, Flying, Lex, Neptunus Lex

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s