DA50 turbine

[Antoine]

Lol between Kai's hilarious crystal-glassing (is this our Dr Piccard on the left?) and Dave's scientific dissection of the aircraft I am glad I am not working at Diamond!

Fact is and remains, turboprops need either an unlimited supply of Jet-A or altitude (preferably both) to make sense.

I can imagine a very rugged plane hauling some serious loads around the tundra, but a low landing speed is a must.
While the initial DA40 versions have very adequate flap systems, I believe this has become the weak spot of the heavier derivatives - DA40-NG, DA42 and anything above. Diamond must come up with a more refined system to keep stall speed in check or they will not sell many bush planes.

The Lancair Evolution is in a different league, but it has these flaps I was thinking about. The ratio of 1:5 between stall speed (61 KTAS?) and top speed (300 KTAS?) is unbelievable. Imagine achieving the same ratio with a stall speed of 40 KTAS. That would be a 200 knot plane that can operate from very short fields.

[Lance Murray]

This is thread drift but...

All were capable of a battery start however every engine you mentioned will have a cooler (ITT or T5 in PT6 Speak) and more reliable start on the 28V GPU vs 24V battery. A battery failure mid start is very bad, you will have to wait less time for the battery to charge, will not have to worry about temperature or charge rate of the battery if it was a NiCad , you can start the second engine immediately without having to wait for a recharge (reduce load), the battery itself would last much longer, etc. With a PT6 Battery start you would be lucky to get above 15% N1 on the battery. You would easily and quickly get 22%+N1 with a GPU start. Your start temp would be over 100 degrees cooler on the GPU.

I watched a guy melt down a PT6 while doing a cross generator start after a battery start. He didn't push up the N1 on the first engine, turned on the generator mid start of the second engine and thats all she wrote. The generator dragged the first engine into a sub-idle condition and completely melted the hot section. Fire and molten metal was coming out of the exhaust. Destroyed the power section also. Anytime I had a GPU available I would always use it.

Heck the DC8 that I flew didn't even have a battery. You had to use a huffer to start it.

RRDart? Was that in a G159?

It is normal to start a turbine powered aircraft from a GPU. This is recommended for all turbines.

I will have to respectfully disagree. Years ago I had many thousands of hours operating PT6, Garrett, & RR Dart turboprops. All started just fine on internal battery. That was normal procedure.

[Tommy]

Dries said the flight lasted about 40 minutes and included agility testing, and the evaluation of power
ratings at various altitudes up to 8,000 feet and climb rates at different speeds. The initial climb rate at 3,300 lbs was 2,800 fpm and the airplane reached a top speed of 175 knots indicated.
Read more at http://www.flyingmag.com/aircraft/turbo ... ZtI2aJh.99

[Colin]

We compare apples with pears all the time. If the pears are ripe, I choose a pear. Apples have a better range and are more tart.

I had a deposit on the DA50. I am smarter now.

One of the old DA40 pilots from the old board is now tooling around in an Evolution. I can't wrap my head around climbing into a home-built that is pressurized. I know that's silly, but that one tiny door...

[GLDAS]

Fact is and remains, turboprops need either an unlimited supply of Jet-A or altitude (preferably both) to make sense.

The Cessna caravan begs to differ on this point

I'd guess this plane is closer to the caravan than the TBM9 on the spectrum of turboprop singles.

Of course, we don't know anything you don't know about this project....

-Dan

[Kent Shook]

The video shows the engine being started using a GPU. If they can't fit a decent sized battery in it, I'm not sure how useful the proposed Tundra variant will be.

As others have stated, that's not unusual for turbines. Back in college, I was a lineman at the local field and we had a King Air for charters. We always used the GPU to start it. Starter motors draw a LOT of juice at low RPMs - On that particular bird, we'd see a 900-amp (!) draw from the GPU at the beginning of the start sequence. That eats batteries pretty quickly.

[Antoine]

Fact is and remains, turboprops need either an unlimited supply of Jet-A or altitude (preferably both) to make sense.

The Cessna caravan begs to differ on this point

I'd guess this plane is closer to the caravan than the TBM9 on the spectrum of turboprop singles.

Of course, we don't know anything you don't know about this project....

-Dan

Well if 60 GPH is not "an unlimited supply"... Maybe I wasn't clear enough: I was just trying to say that turboprops are very inefficient at lower altitudes, not that they were useless. The SFC of turbines is only close to that of piston engines at high altitudes but obviously if you are operating out of a bush strip and want the ruggedness of a turbine, there's no alternative.

[rwtucker]

I don't know . . . a quick calculation shows 40/30 GPH takeoff/cruise. Providing for the typical 5-hour run could end up with the anemic payload of the DA40.

Even assuming a 220 kt. sub-FL180 cruise, the value proposition is weak in relation to the existing market: presumably greater stability than Lancair & Cirrus (based on legacy) but significantly higher operating and insurance costs when compared with any of the fast piston singles which are also suitable for the kind of mountain flying that rules out the spool up delay of turbines. (I would never fly one where I typically fly.)

To me, putting less money than it will take to bring the turbine to market into a new 300 HP diesel DA50 finds a better market niche. Right now, there are probably a few thousand people who want, essentially, a true 5-place "DA40" that is a tad faster. I'm on that list.

[CFIDave]

To me, putting less money than it will take to bring the turbine to market into a new 300 HP diesel DA50 finds a better market niche. Right now, there are probably a few thousand people who want, essentially, a true 5-place "DA40" that is a tad faster. I'm on that list.

I don't disagree, but I suspect Diamond would say that you should be a customer for a DA62. It's a 5-place (or optionally 6-7 place) DA50 that happens to have two smaller 180 hp diesels instead of a big 300 hp diesel, and that's a "tad" faster than a DA40.

[rwtucker]

I don't disagree, but I suspect Diamond would say that you should be a customer for a DA62. It's a 5-place (or optionally 6-7 place) DA50 that happens to have two smaller 180 hp diesels instead of a big 300 hp diesel, and that's a "tad" faster than a DA40.

I know Dave but for some of us (me, at least) I did the pluses (there are a bunch of them) and minuses and decided against a twin. I envy you guys every time a DA42 zips by but 300 horses (even 250 maybe) in a slightly stretched DA40 body is my perfect distance aircraft. Then, I'm building a Carbon Cub!