I fly a Cessna P210 with a turbine conversion. Used to fly a turbo Arrow.
I'm based in the south and I have found engine heat at altitude to be the
limiting factor for both the turbine and piston. On cold days, you can go a
good 20-30 knots faster than hot days at altitude with the turbine. On hot
days with my Arrow at altitude, I always seemed to be worried about cylinder
head temps.

The Allison engine is much lighter than the piston, but you have to carry
more fuel, so it's a wash. Plus Jet-A is 10 percent heavier than Avgas.
However, the lighter turbine engine allows for tip and aft auxiliary tanks
which extend my range to 1200 nautical miles. Fuel burn is 25 gallons--quite
a bit more than the piston, offset slightly by the lower cost of Jet-A.

Nevertheless, I have found increased speed, although nice, not nearly as
important as the comfort of knowing a turbine has substantially higher
reliability than a piston. Next is the quiet and smoothness of the plane,
it's climb ability, huge feathered-prop glide ratio and, being pressurized,
the ability to get quickly on top of the bumpy cumulo level in the summer.




wrote in message
...
On Fri, 02 Jan 2004 05:37:58 GMT, "Mike Rapoport"
wrote:


I think (guess) that they were looking for somewhat better performance
than
a turbocharged piston Bonanza across the existiong flight envelope, but
not
to extend that envelope too far in either speed or altitude. If they put
an
engine into the airplane that would make 300hp at FL310, they would
probably
have to completely re-flight-test the airplane.

You seem to have hit the nail on the head, intentionally or
accidentally. A turbo-normalized or turbo-supercharged engine in an
A-36 should have no issues with delivering 75% of rated TO hp well
into the teens.

Again, it has admittedly been several years since I did the research
for a prospective customer (for whom $$ was by no means an issue), but
the power "curve" of the 250 was less than desirable when compared to
a turbo piston-pounder.

Specific fuel consumption was approximately 1/3 higher, with the
additional fuel storage neccessary to retain "acceptable" range
capabilities.

There are many existing aircraft types that have been "re-engined"
with powerplants drastically exceeding the original installations. In
a lot of cases, no "flight-test"-ing is required, nor is it needed.
Engine operating limitations are changed so as not to exceed the
original levels.

I would certainly agree that testing would need to be performed if
increasing the usable hp-thrust rating.

I am a little confused by your post as well. An engine can only make its
thermodynamic horsepower at sea level and ISA, so you are below that at
any
flight altitude.

I apologize if I wasn't clear, or it may be a case of
miscommunication. It's likely when looking at "newer" t-prop aircraft
you will notice that the gas generator is likely capable of exceeding
airframe limitations at max thermo-hp.

Hence, at altitude it has no problems producing a very high percentage
of "max take-off" power. I'm sure you know this.

They are few and far between, but there are A-36's flying around with
350 hp turbo-supercharged Lycoming engines. Aside from the differences
in initial rate of climb, I would be willing to bet the the overall
performance numbers would be more than comparable to the turbine
conversion.

The guy I spoke to that had one could only lament the fact that he had
to burn 22-25 gph in cruise...

Regards;

TC

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