DA42 vortex generators

Any DA42 related topics.

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dgger
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Re: DA42 vortex generators

Post by dgger »

That is odd. Thanks for checking!
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Re: DA42 vortex generators

Post by dgger »

So, I finally got mine fitted a few weeks back and did quite a bit of flying. After 55h hours airborne I pulled the data logs to compare them to my logs without VGs fitted. Here is what I found at various power setting:

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Yes, this is only 55h hours worth of flight logs, but I would be suprised, if the impact on cruise performance is indeed zero. YMMV, but it is most certainly a number great than zero.

Other than that I was pretty impressed to see that the performance data in the POH is indeed very accurate for my aircraft:
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jb642DA
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Re: DA42 vortex generators

Post by jb642DA »

Peter -

Did you do any slow speed flying (stalls, Vmc work, blue line flying) to compare before and after?

Thanks for posting all the other data!

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dgger
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Re: DA42 vortex generators

Post by dgger »

Yes, I did indeed. I have found there to be some improvements, but they were nowhere near as pronounced as I had hoped. At the same time the aircraft did handle differently/better. To me it felt like it wanted to "fly more" and slower and earlier on departure, though the raw stall speeds did not quite back up that feeling. I will need to look up the numbers at home and come back to you later.

In any case, rather than improving the raw stall speeds, my main interest was to improve short-field performance. I have not yet pulled this data out of the logs, but will keep you posted, once I do.
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ememic99
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Re: DA42 vortex generators

Post by ememic99 »

Thanks for sharing data - nothing can beat real life experience. TBH I don't see much gain while loss on TAS is obvious.
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Re: DA42 vortex generators

Post by TimS »

Nice data. Makes me wonder if I would want them for flying into smaller airports in Europe.
The cruise penalty I think would not be worth it flying around the States, but in Europe I know they tend to grass and shorter runways.

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Re: DA42 vortex generators

Post by ememic99 »

How short? Ground roll and takeoff distance are not the only parameters when choosing the runway.
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Re: DA42 vortex generators

Post by TimS »

ememic99 wrote:How short? Ground roll and takeoff distance are not the only parameters when choosing the runway.
Umm, you live in Europe you probably know better that I. :D
My wife is from the Alsace region of France. I figure we would likely go there, and also to the South Eastern part of France in the Alps where she has family. Otherwise, we tend to travel about 50% to regular metro areas such as Lyon (France) and Florence (Italy); with the rest of the time in smaller towns such as Sarlat La Canada (France).

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Re: DA42 vortex generators

Post by ememic99 »

I don't have much opportunity to land short airfields but I land from time to time to 720m paved and 850m grass fields. It's on the edge of what I'm comfortable with especially when I think about aborted take-off at V1/VR speed and EFATO.
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Re: DA42 vortex generators

Post by dgger »

Meanwhile I flew a total of 180h with Vortex Generators and my numbers are much more solid. Time for a final G100 readout.

My verdict: You loose about 4-5KTAS on low power settings and 3-4KTAS on higher ones. Gain is whatever you feel like it might be, but not necessarily measurable - all in all the impact is quite limited in my experience, though the significantly reduced Vmca in practice gave me comfort when rotating early.

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