More FlightTesting

[rodsmith]

Last winter I completed all the Phase 1 flight testing cards before I installed VGs. The only flight tests I redid after installation were the full stall series and landing and takeoff distances which all definitely imrpoved. I have wondered how the VGs might impact other speeds such as Vx, Vy, and best glide. Needing to complete my Aircraft Operating Handbook, I decided it was time to redo the climb and glide speed tests. Early January provided a high pressure system with very still air for a few days. Winds aloft ranged from calm to 5kt. There was no detectable lift or sink flying early in the cold mornings. I spent three hours over two days testing at 5kt intervals. Testing was done at 2400#s 17.6" CG. Interestingly Vy and Vg both decreased, Vg from 75 to 70. Vy from 65 to 62. Climb rate at 60 and 65kts was within 10 fpm so I tested at 62 and it was 25 fpm higher. Vx remained the same at 55k. I feel that these were accurate results, the air was very stable and I was able to hold the speed +/- 1kt. I feel like the results were quite a bit more reliable than my earlier testing which was done with less stable air and I had more trouble holding the exact speed. Did the VGs change Vy and Vg? Don't have enough information to know, may have just been better testing. I found that flysto.net provided more accurate altitude numbers at 1 second intervals than I was able to record as the timer hit 60 seconds.

[Bcone1381]

So I think your saying Flysto.net by itself is suitable for data collection.

As I consider your numbers.....the data shows VG's ability to organize airflow at high AOA effects the feel of the controls and speed of the stall. It is absolutely logical to me to predict they would effect some Vspeeds too. I wonder if you have a discovery that the industry knows little about?

Don't let this next Q hijack this thread about Glide Ratio.....Did your glide ration improve noticeably? My wing is still clean (no VG's). My power off glide performance resembles a set of car keys. I think its drag from the Trailblazer Prop. I'd like to have the group validate that my experience is normal. I'm pretty fair at doing a Power-off spot landing in a Champ or C-150. In my Patrol I better aim for the center of the airport if I am going to make the runway when I pull the power back to idle abeam the numbers.

[rodsmith]

I forgot to mention that my glide ratio improved from 9.1 to 9.5. My 3-blade prop is also a very effective air brake. I've learned not to go to idle until the runway is under me. Procedure if power is lost is pitch for best glide speed and pull the prop control full out. You can feel the acceleration when doing that. I haven't done a glide test at fine pitch, imagine it would resemble a rock.