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Gentlemen:
Over the holidays I had an opportunity to fly in N750TL, the factory IVP with the Walters engine and Hartzell prop. Thought you might be interested in the notes I took during demo rides for myself and two other friends.
1) Fuel Capacity in the wings is 57 per side (114 total) and a belly tank is available for an additional 28 for a total of 142 gal. The belly tank conforms well to the design of the plane and is hard to notice unless you have a non-turbine to compare it with so drag may well be minimal. I am told a belly tank of 40 gal is in the works.
2) Fuel Burn and performance was observed to be as follows:
GROUND IDLE: 23.2 GPH
CRUISE CLIMB: (96% RPM) 62 GPH 220 KIAS @ 2000 FPM
PERFORMANCE CLIMB: (97% RPM) 52.9 GPH 180 KIAS @ 4000 FPM
LOW ALT. CRUISE at 6,500 MSL (85% RPM) 33.6 GPH @ 225 KIAS
MID LEVEL CRUISE at 15,500 MSL (84.2% RPM) 29.26 GPH 195 KIAS 270 KTAS
DESCENT: (70% RPM) 14.8 GPH and 2,000 FPM
3) PRESSURIZATION: - Lancair has solved the heated bleed air problem. I was told it involves multiple intercoolers but the result is pressurized airflow that is at least as cool as a piston IVP and maybe a slight bit cooler. In fact there is so much bleed air available that a setting of only 1/2 on the cabin air butterfly valve yeilds 5 PSI no problem. If the pressure vessal could handle it, I would think flight above FL 290 possible but that is speculation on my part.
4) Air Conditioning - The all electric AC unit which they use is great. I think someone in Bend invented it (?). Once you throw the switch at max setting you can feel your hair blowing there is so much air flow and it probably lowers the cabin temp by 10 F every 30 sec. Forget hanging meat---you could FREEZE it! I did not check to see the amperage draw since it is all electric but the cooling performance was impressive. The plane in question was experiencing interference between the AC unit and the avionics so we could only use it on the ground but it sounded like just an un-grounded blower motor so probably not a big deal.
5) SUMMARY: A very impressive hot rod. The climb numbers they promise are there (I suspect if you pulled it back to 150 KIAS you would easily see 5,000 FPM) but since we did not go above 15,000 I cannot speak as to ultimate cruise performance. If you look at the above numbers though it would appear that 310-320 KTAS at FL 250 on 29-30 GPH seems in order.
The viability - in my mind - clearly rests on whether more fuel can safely be carried given its thirsty consumption in low level flight. It is not unusual to hold at some airports for 30-45 min in IMC with possible divert thereafter and this would be at the worst portion of the performance/fuel economy curve of the IV-PT. Personally, I also worry about the belly tank approach in view of the fire risk in a forced landing situation. If there were a rapid fuel dump arrangement on the belly tank this would be a huge improvement. Some of you engineering types out there can probably comment on this since it is used in airliners right?
Having said all of this am I a buyer? No. While the jet like climb is a real kick I think since I already have a IVP with a piston engine, the cost to gain this advantage and what seems like moderate speed increases are out weighed by the greater range of the piston version.
However -- if the belly tank/fire risk issue were solved and if a six place version were offered I think Lancair would kick TBM and Piper right out of this market niche probably for half the price too!
This Lancair 6-PT is what I hope will grow out of this product and I would be happy to be a customer for a 6 place turbine.
Anyway, ones mans opinion and observations. Hope this was of interest.
Regards,
Dave Riggs
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