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DA42-VI Real-life Performance

Posted: Sat Jan 04, 2014 10:44 am
by Yankee17
If anyone is interested in real-life performance of the VI, I posted a couple of longer trips in "reports". This was a round trip with two adult males and full tanks (main & aux) for both legs. Also full de-ice tank with another 10 ltr in reserve.

http://www.diamondaviators.net/reports/flights/5369
http://www.diamondaviators.net/reports/flights/5368

Re: DA42-VI Real-life Performance

Posted: Sat Jan 04, 2014 2:10 pm
by Jean
Awsome !
That must have been a beautiful trip.
Is fuel comsumption indicated for both engines ?
What was the power setting ?

Re: DA42-VI Real-life Performance

Posted: Sat Jan 04, 2014 2:37 pm
by Yankee17
Jean wrote:Is fuel comsumption indicated for both engines ?
What was the power setting ?
On the out leg, FF=7 gph per side. Power setting was 80%. FL140. TAS=180
On the return leg, FF=6.9 gph per side. Power 77%. FL120. TAS=173.

We were battling a stiff headwind on the way back, so I stayed lower. If I want more endurance, I pull power back to 70-75%a and can count on 6-6.5 gph per side. At FL160-180 a TAS of 180 at that power setting is not unheard of.

Re: DA42-VI Real-life Performance

Posted: Sat Jan 04, 2014 2:42 pm
by Rick
Jean wrote:Is fuel comsumption indicated for both engines ?
Our REPORTS section doesn't handle the DA42 engine data correctly yet. I'm trying to find some spare time to work on it, but no luck yet. I believe the fuel consumption (and most other engine data) is only for the first engine at this point.

Re: DA42-VI Real-life Performance

Posted: Sat Jan 04, 2014 2:57 pm
by Yankee17
Rick wrote:I believe the fuel consumption (and most other engine data) is only for the first engine at this point.
That seems to be right, comparing to the CSV file. Usually, we'll try to run the engines symmetrically, so the data you see now should be a pretty good indication. (And, if I can keep the wings level, the altitude readings should be quite similar for the two engines, as well!) :D

Re: DA42-VI Real-life Performance

Posted: Sat Jan 04, 2014 10:15 pm
by CFIDave
I've found the way to extract great performance in the DA42-VI is to fly high (the plane, not the pilot unless over Colorado :D ). The rule of thumb seems to be an increase of 3 knots TAS for each 2000 feet added to the altitude.

Except when facing bad headwinds at higher altitudes, our "sweet spot" is the recommended 75% cruise power, burning 6.6 gal/hour per engine (13 gph total), and flying on O2 at around 15,000 feet. The result is usually around 180 knots TAS. This is with 2 adults, full fuel and de-ice, and luggage. Our plane seems to be at least 4 knots faster than what's published in the AFM/POH at any altitude and power setting.

Re: DA42-VI Real-life Performance

Posted: Sat Jan 04, 2014 10:56 pm
by Yankee17
CFIDave wrote:Our plane seems to be at least 4 knots faster than what's published in the AFM/POH at any altitude and power setting.
I concur.

Re: DA42-VI Real-life Performance

Posted: Sat Jan 04, 2014 11:12 pm
by carym
CFIDave wrote:I've found the way to extract great performance in the DA42-VI is to fly high (the plane, not the pilot unless over Colorado :D ). The rule of thumb seems to be an increase of 3 knots TAS for each 2000 feet added to the altitude.

Except when facing bad headwinds at higher altitudes, our "sweet spot" is the recommended 75% cruise power, burning 6.6 gal/hour per engine (13 gph total), and flying on O2 at around 15,000 feet. The result is usually around 180 knots TAS. This is with 2 adults, full fuel and de-ice, and luggage. Our plane seems to be at least 4 knots faster than what's published in the AFM/POH at any altitude and power setting.
Just for comparison, and for whatever it is worth, I fly my 1.7's at 75% power at 5.5 gal/hr/side and get 160 knots TAS at 15000 feet (with full tanks, 2 adults and luggage, full de-ice, and on oxygen). At 18% more full usage you get 12% more speed. Pretty good increase in speed with not that much more fuel burn. It must be related to those small but numerous airframe cleanups they did for the -VI. I find that usually I really don't save much time in going up that high unless I am on a very long (3+ hours) x-country.

Re: DA42-VI Real-life Performance

Posted: Sun Jan 05, 2014 4:32 am
by Henrik
I tend to do longer trips (4+ hrs) in my DA42-VI & typically file FL170/180.

The engines perform even better at altitude here in the tropics with the high density altitude. (ISA+15/20)

I generally cruise somewhere around ktas 185-190 @ 77% power. Speed is just really addictive & since Jet A is so relatively cheap here, a slightly higher fuel flow is no big deal.

Having said that, at lower altitudes like FL130, if you're looking for "max" high speed cruise & don't care about fuel flow/range, 85% generally makes the best sense - the speed difference between 92% and 85% is just 4-5 kts, not really worth it to thrash the engines.

At FL180 you won't get more than 82-83% max power on the Austros, but it'll give you somewhere around 193-195 ktas. Best speed I've ever had at max power 82%, ISA+15 & FL 180 was 198 ktas.