# Would you be interested in a 200 hp turboprop?

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#### Merlin

##### Active Member
Sorry; you can't. At 50 GPH, and the typical 35-45 gallons of fuel capacity in a typical 2 seat homebuilt, by the time you taxi, take off, and climb to pattern altitude, you'd be at VFR minimum fuel. 200 kts on downwind might *sound* cool, but it would be counterproductive at best.

edit: If flow is 50 GPH @16K feet, you couldn't even leave the ground legally; it's got to be much worse near sea level.
I understand your conserns, however its not meant to replace a piston engine. The whole airplane has to be built around the turboprop, which means focusing on fuel storage.

#### Brünner

##### Well-Known Member
HBA Supporter
There's the PBS engine already, rated at 250 hp (IIRC). I don't know how many units they sold, but I'm afraid the numbers are pretty low.

#### TFF

##### Well-Known Member
A turbine’s advantage is to get high and take advantage of true airspeed. 20,000 ft is the only way something like a Legend makes any sense, but it’s not pressurized. It doesn’t stay in the air long. Lancair PIV is good, nice if it was a little bigger. Going 200 kt but only flying 1.5 hours would mean a fuel stop to get to Oshkosh from my place where a RV 7 at 165-170 true will have an hour more before hitting reserve with gas. Get there faster going slower. A TBM700 idles at 30 gal an hour, so it would stink as a knock around plane. Airshow aerobatic plane is about it, which is about all a jet BD5 is worth. Enough fuel to fly a dozen times down a runway.

#### Merlin

##### Active Member
This engine uses a recuperator to lower BSFC without resorting to more compressor stages. Proven technology in stationary gas turbines and the Chrysler and Rover automotive gas turbines of the 1960s. The trick is making that efficient, light and compact enough for aero applications.
Seems like a neat idea

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#### Riggerrob

##### Well-Known Member
This engine uses a recuperator to lower BSFC without resorting to more compressor stages. Proven technology in stationary gas turbines and the Chrysler and Rover automotive gas turbines of the 1960s. The trick is making that efficient, light and compact enough for aero applications.
When you consider how much energy is wasted by most engines ... how much wasted energy is merely dumped out of exhaust pipes, it is obvious why small turbines have such high specific fuel consumption.

Recuperators "salvage" waste heat from exhaust and re-route it back into intake ducts to pre-heat intake air. This pre-heated air returns energy to the combustion chambers and requires less fuel to heat to operating temperatures.
Marine and AFV recuperators tend to be as large and as heavy as the engine core. For example, the recuperator in an M1 Abrams tank is a large diameter series of rapidly rotating discs that heat in the exhaust side of the recuperator, then those discs transfer that excess heat to the intake duct.

This new recuperator is much simpler than previous recuperators. The latest Turbotech drone turbines use much simpler recuperators that are little more than extended burner cans. These extended burner cans expose intake air to hot (burner can/combustion chamber) walls. Those extended walls separate intake from combustion chambers and are long enough to recuperate (via conduction) some waste heat before injecting that pre-heated air into combustion chambers.

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#### Marc Zeitlin

##### Exalted Grand Poobah
This engine uses a recuperator to lower BSFC without resorting to more compressor stages. Proven technology in stationary gas turbines and the Chrysler and Rover automotive gas turbines of the 1960s. The trick is making that efficient, light and compact enough for aero applications.
The TurbAero webpage indicates that this engine weighs about 270 lb. This is 20 lb. less than a 180 HP Lycoming O-360. It also indicates a BSFC of 0.52, which compares particularly unfavorably with the approximate 0.4 - 0.42 that the 180 HP Lycoming can achieve when using EFII/EI and aggressive leaning.

They indicate a TARGET TBO of >3K hours (obviously unproven at this point) vs. a proven TBO (granted, with a large standard deviation) of 2K - 2.4K for the Lycoming engine.

With no price indicated and no proof of performance and or TBO, everything is speculation. But given the large increase (~25%) in BSFC between the two engines, very small difference in weight, and unproven TBO difference, I'm having a hard time seeing any advantage in performance or TOTAL cost in this turbine engine. Possibly, for aircraft that fly 500 - 1000 hours/year and need minimal maintenance attention, the additional fuel cost might be acceptable. For someone that flies 50 - 100 hours/year and doesn't pay for maintenance, I cannot for the life of me see the appeal - I'll be paying 25% more for gas for the foreseeable future, and for what?

Magically get the BSFC down to the 0.4 - 0.42 level, and I'm in.

#### rv6ejguy

##### Well-Known Member
I think the .52 BSFC target for a small turbine like this gets it into the "acceptable" realm for those who'd consider a turbine. I'd never underestimate the "cool" factor in this market. It remains to be seen if they can meet power, BSFC, longevity and price points here but they do have an experienced team working on this and have keep pretty quiet on it as development continues. The principal has posted very realistic goals to date IMO and they have a feasible business plan in place as well- something that others trying to enter this market have never had.

Best of luck to them.

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#### rv7charlie

##### Well-Known Member
"With an optimum cruise power at 10,000’ in the range 150-180hp with a targeted specific fuel consumption of around 0.52 lbs/hp/hour, "

I have a targeted performance number of 200 mph at 10 gph for my Mazda Renesis powered RV7. I'll be wildly ecstatic if I achieve that.

I'm pretty sure that my emotion would be swamped by Turboaero's if they achieve theirs; I'm confident that my odds are quite a bit better, and I'm not confident in my odds.

IF they can hit the target, at an affordable price (meaning new Lyc prices), then .52 is easily tolerated; fuel price would make up the spread and the only thing lost is payload/range.

#### Toobuilder

##### Well-Known Member
HBA Supporter
Log Member
A turbine’s advantage is to get high and take advantage of true airspeed...
A turbine's "advantage" is the small form factor, high power to weight, low parts count, and theoretical reliability. The harsh reality is that it needs to go high to make sense from a fuel burn perspective. Thats a tough nut to crack, and the smaller the engine, the less opportunity to gain efficiency.

Frankly, I dont care whether the engine on the nose of my airplane has pistons or blades, or burns gasoline, kerosine or unicorn flatulence. The only thing that matters is meeting performance and reliability requirements with the best cost per hour over the life of the engine. It comes down to just (very) simple math.

#### D Hillberg

##### Well-Known Member
Its a super niche market and there is no competition, the nearest turboprop is the allison 250 and will cost you \$350k

The altitude is 16000ft, the cruise sfc is ~50gallon/h
Your way off on the numbers
PT 6 SP twin pac has 100 gph in a 212
T-53 700 90 gph in our UH 1
Allison 250 series is 22 to 25 ghp with 270 hp
Solar T62 T32 is 13 to 15 gph for 150 hp
Honeywell GTCP 36 - 55 c 9.9 gph with 150 hp

You can pick up an old Allison for 40 to 60 grand depending on what modules are timed.

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#### rv6ejguy

##### Well-Known Member
The GTCP 36 is around 1 to 1.1 BSFC. A single centrifugal compressor stage only gives around a 6 to 1 PR which isn't conducive to low BSFC. The T62 is around 1.3 BSFC. This is why if the TurbAero engine will really achieve .52, it will cut fuel consumption in half compared to these old APU designs. That's pretty revolutionary for a "low cost" small turbine.

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#### Rik-

##### Well-Known Member
Having owned and screwed with a few of the Allison C20’s you can find a C18 which makes 300ish HP with a continuous rating of some 230-250 ish depending upon the temperature. Then fuel burn would be something like 22-24 gph if your cranking on it.

You can get these timed out or out of a crashed bird for less than 30k. They have a 6600 rpm output which will need a reduction unit but the engine is only like 140 lbs. Room for a reduction unit weight.

#### D Hillberg

##### Well-Known Member
Having owned and screwed with a few of the Allison C20’s you can find a C18 which makes 300ish HP with a continuous rating of some 230-250 ish depending upon the temperature. Then fuel burn would be something like 22-24 gph if your cranking on it.

You can get these timed out or out of a crashed bird for less than 30k. They have a 6600 rpm output which will need a reduction unit but the engine is only like 140 lbs. Room for a reduction unit weight.
Lots of old Allisons all over

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