JetProp DLX

By now, just about anyone who's been paying attention to the news knows that The New Piper Aircraft Corporation will certify its new Meridian this summer. This is a Pratt & Whitney PT6A-42, 500-shp, turboprop-powered version of Piper's PA–46 Malibu. This impressive new turbine single, New Piper says, will turn out a maximum cruise speed of 267 knots at 25,000 feet while burning approximately 31 gph of Jet A. There are currently 144 orders for the $1.375 million Meridian; if you placed an order today, you wouldn't be able to take delivery until 2002.

For those who can't wait to get in line—and who already own a Malibu—there's Rocket Engineering's JetProp DLX conversion. This radical modification lets you turn your 310- or 350-hp piston-powered Malibu or Malibu Mirage into a fire-breathing, 560-shp turboprop. The Spokane, Washington company bolts a Pratt & Whitney PT6A-34 engine (derated to 560 shp) and a four-blade, reversible Hartzell propeller to your plain-Jane Malibu, fits it out with a 13.5-gallon header tank, dual batteries, a backup alternator, a Shadin fuel computer, a nose baggage compartment, and more—all for the price of $599,000 and a 12-week down time.

The promise is more speed and range than the Meridian, for less money. The speed comes via the extra 60 shp that the -34 engine offers, and the design of the engine air inlet scoop. The scoop's pitot-like function lets the engine recover as much a 500 pounds of torque from the propeller's thrust—torque that the engine doesn't have to produce at altitude, where lowered air density causes unavoidable power losses. The range comes from the fuel economy enabled by that thrust recovery, the fuel in the header tank, and the addition of outboard fuel filler caps on the JetProp DLX's wings. By adding these caps outboard of the usual filler cap locations of the Malibu/Mirage, the wing tanks can be made to hold 10 gallons more per side. This, plus the fuel in the engine header tank, gives JetProp DLXs (can we just call it a DLX from now on? The DLX, by the way, stands for the Roman numerals signifying 560—as in 560 shp, get it?) a 151-gallon fuel capacity. Malibus have 120-gallon maximum fuel capacities; Meridians can carry up to 170 gallons of fuel.

"Sure, we use a smaller engine [thermodynamically] than the Meridian," says Rocket Engineering's president and CEO, Darwin Conrad. "But because we capture the thrust of the propeller the airplane goes faster. It all adds up to an airplane that trues out at 255 knots at 27,000 feet while burning 30 to 31 gph. The Meridian will go just as fast, but burn about 35 gph." (Piper has not yet released fuel burn figures for the Meridian.) Conrad says the maximum IFR range of the DLX is "1,250 to 1,300 nm."

Conrad also claims that the DLX's runway performance will beat that of the Meridian: an initial rate of climb of 3,000 fpm; a takeoff over a 50-foot obstacle of 1,200 feet; a landing over a 50-foot obstacle of 1,000 feet; and a minimum stopping distance of 500 feet.

Impressive claims, all. To get some first-hand impressions of this fire-breather, we asked Dr. Dan Lawson to bring his DLX by AOPA headquarters for a familiarization flight and a photo shoot. Lawson, who owns his DLX with two other partners, uses N126SR for business and pleasure. Rocket finished his airplane last fall, and Lawson has already put close to 200 hours on it.

Of course, the first thing you notice about a DLX is that huge snout. From the base of the windshield, this thing extends what looks like 20 feet, and is adorned with a propeller sporting stubby, paddle-like blades as wide as an outstretched hand. A peek into the nose baggage compartment gives you a look at a carpeted box that intrudes into the baggage space. This is the engine's header tank.

Firing up the DLX calls for some unusual extra steps. First you turn on the ignition and hit the starter half of the starter-generator switch. At the same time you hold down a switch labeled "Dual Batt"—and keep it held down; this puts the ship's two batteries in parallel for extra starting power. After gas generator speed rises above 12 percent, move the red condition lever forward on the power quadrant, wait for the light-off (a rise in interturbine temperature (ITT), and that neat "foom" sound. At 52 percent, turn off the starter, let go of the Dual Batt switch, and turn on the alternator switch. Now select Battery 1 on the battery select switch for no more than 30 seconds. Then select Battery 2 for the same time. This recharges the batteries after their starting exertions.

Even though the prop—and the nosewheel—is w-a-a-a-y out there, taxiing is conventional. There's so much residual thrust that the DLX will taxi smartly with the thrust lever in the Flight Idle position. You can use the brakes to slow you down, but to save them it's best to flatten the prop blade angle by easing the thrust lever aft, into the Beta range. That's the range just before reverse thrust, and the range that makes that cool growling sound.

Maximum torque for takeoff is redlined at 1,337 lb/ft, so run it on up while holding the brakes and making sure that you've cranked in some right rudder trim for the initial climb. Rotate at 80 kt, climb out at 120 to 140 kt (V _X and V _Y are 90 and 110 kt, respectively, but at those speeds the nose does a great job of obstructing the view ahead), and you'd better come back on the power to 800 lb/ft of torque. Why? Because at high power settings it can be very easy to blow right past the DLX's redline of 172 kt indicated. Like every other turboprop-powered airplane, redline on the airspeed indicator is redline, period. In turbofan-powered airplanes with air data computers, a red-and-white-striped (hence "barber-pole") needle moves according to the airplane's altitude, automatically providing the maximum operating speed for any given atmospheric condition.

With the DLX you've got a green arc on the airspeed indicator—right up to redline. There is no yellow arc. What this means is that you have to keep a very close eye on airspeed and power.

The day we flew, Lawson and I were nearly at gross weight. Our initial rate of climb was 2,500 fpm at 140 kt indicated, and we shot to 10,500 feet in less than five minutes. In cruise, with torque set to 800 pounds and the propeller set to 2,100 rpm, our indicated airspeed settled right on redline and the fuel burn was 230 pph, or about 34 gph. Lawson says he routinely sees indicated airspeeds near redline and true airspeeds in the 255-kt range at FL270—confirming Conrad's assertions.

Back in the pattern, it's 10 degrees of flaps to begin the slowing procedure. V _FE for this first notch of flaps is 169 kt, and the landing gear can be lowered at the same airspeed (the V _LO for raising the gear is 130 kt). This, and a power reduction to 400 lb/ft of torque, makes slowing down a snap.

Downwind was flown at 120 kt; on base and final we held 110 knots and extended the second, 20-degree increment of flaps; and with full flaps our target fence speed was 90 kt. You can make nice, roll-on DLX landings by slowly bleeding off airspeed in the usual way, or carrier-style straphangers by pasting it on, throwing in full reverse thrust, and standing on the brakes.

Comparisons with the Meridian are inevitable—even though the Meridian has yet to hit the market. Naturally, Rocket Engineering is eager to emphasize the DLX's bright future.

Want some examples? Conrad reports that a V _NE increase—to 187 kt (the Meridian's projected V _MO)—is in the works. This speed increase will apply retroactively to all DLXs, Conrad said. Likewise, a gross weight increase, from today's 4,300-lb maximum takeoff weight to 4,600 lbs (the Meridian is advertising a 4,850-lb maximum takeoff weight)—is soon to come. All of this weight increase will go to useful load, Conrad says. This will be a welcome improvement to owners like Lawson, whose airplanes now have maximum useful loads in the 1,330-pound range, and useful loads with full fuel of just 320 pounds or so. Meridians will have maximum useful loads in the 1,607-pound range.

"The Malibu [airframe] is surprisingly stronger than we anticipated," said one Rocket spokesman, who emphasized that the "DLX conforms to everything that FAR Part 23 requires…we did 10 different destructive tests…we tried to rip the firewall off…we landed with the force of a 39-knot sideways drift… we tested all components of the airframe to 100 percent, then 150 percent of destructive load limits, and man, you should have heard it creak and groan..."

When I asked The New Piper about the DLX project, a spokesman said, "There's a very good reason why the FAA required us to build four conforming test airplanes for the Meridian project, one of which was a dedicated static test article. There's also a good reason why we made the volume of the Meridian's horizontal stabilizer 37 percent greater than that of the Malibu."

And with that, let's suspend the public relations duel. A future report on the Meridian will give us a chance to better evaluate that airplane.

Rocket is no stranger to upgrading high performance, single-engine airframes. The company's Missile (a Mooney 201 fitted out with a 300-hp Continental IO-550 engine) and Rocket (a Mooney 231 or 252 souped up with a Continental 305-hp TSIO-520 engine) have met with great popularity, with some 200 of those STCed modifications in service.

Rocket's DLX training program seems thorough. Depending on a customer's experience and proficiency level, a ground school lasting anywhere from three to 10 days is conducted at Rocket's Spokane facility. Then comes some individual flight instruction, followed by a one-week stint at FlightSafety International's Lakeland, Florida facility, where Rocket has set up a DLX simulator. Three-day recurrency courses are also available.

As with any step-up turboprop, the DLX offers the kind of performance and flexibility that's a welcome change from piston-engine flying. It's available now; some 27 DLXs have been delivered as of this writing, just under two DLXs are built per month, improvements are on the way, and the airplane has found its niche. If you currently own a Malibu/Mirage and have always longed for turboprop power, reliability, and—dare we say it?—sex appeal, then you owe it to yourself to check out the JetProp DLX.

E-mail the author at [email protected].