New Power For Old Airframes
By Nadav Eiron, ANN Correspondent
Rocket Engineering, famous for its JetProp conversion of the
Malibu and Mirage and its Bonanza TurbineAir turbine conversion, is
now moving on to its next target: the Beechcraft Duke. Tim Moore, a
marketing and customer support specialist for Rocket, explains why
the Duke is such a good candidate for their PT6A based
conversions.
With the high operating costs, and bad reputation of the
Lycoming TIO-541 on the original plane, airplanes on the used
market are available for prices as low as $150,000. Add a
turbo-prop conversion, and such an airplane is turned into a much
more capable (as in 300 knots cruise), not to mention reliable,
bird, for a total cost that is attractive not only when compared
with new airplanes, but even with used turbo-props.
The Royal Duke conversion is a complete firewall forward
replacement of the original Lycomings with PT6A's - either the -21
variant or the -35 variant. The PT6A-21 will be flat-rated to 500
SHP and the -35's to 550 SHP. With so much power, performance is
radically improved. Rocket guarantees 1800' ground roll with MTOW
and an initial climb rate of 4500 ft/min. In fact, when light, the
plane can do 6000 ft/min.
Cruise numbers are also impressive, with 301 knots max speed and
285 knots normal cruise at FL270. These numbers are for an airplane
converted with the -35 engines. Currently the company has two
airplanes already converted with the -35's that are used for flight
testing. The next airplane to be converted will use the -21
engines, and the expectation is for a 25 knots slower cruise with
that engine.
Single engine performance is equally impressive: According to
Tim Moore, the airplane will do 1600 ft/min with one prop
feathered. Tim describes single engine handling as "jet like",
because the engines are slightly canted to minimize asymmetry.
Part of the problem with turbo-prop conversion of GA pistons is
the limited load carrying capability because of the turbines'
thirst for Jet-A. However, the Duke seems to do very well on weight
too. The complete conversion results in an airplane about 230
pounds lighter than the original. Rocket adds two 15 gal. nacelle
tanks to the up to 232 gals tanks of later models B60 Dukes for a
total of 262 available gallons of Jet-A. Useful load for the
conversion is 2600 pounds, allowing for five people in the cabin,
even with full fuel. IFR range is 1200nm.
Flight testing is practically completed, and Tim Moore's best
guess for when the STC will be done is mid-October. Rocket
recommends (but does not require) adding winglets, VG's and aft
strakes from Boundary Layer Research to make the airplane perform
at its best.
The total conversion with brand new PT6A-35's and Hartzell
reversing props will cost $887,000, and the -21 conversion will
come in at $100K less.
The Duke is not the only new thing happening at Rocket
Engineering. Customers are asking and Rocket is working on
delivering a glass cockpit installation for their conversions. The
solution will be based on the Sagem glass cockpit offering, and
will include three screens. Availability is projected to be about a
year out, with the Bonanza being the first to get the glass.
NTSB Prelim: Piper PA-23
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