Installing Stolspeed VGs s on the Zenith 801

Main Wing

For the main wing, place the VGs with their front tips 155 mm in front of the main rivet line on the top of the wing. The first 15 VGs in from each wingtip are at 60 mm spacing, and the rest at 90 mm.

Tail

For the tail, place the VGs on the elevator rather than the horizontal stabilizer. Place the front tips of the VGs 120 mm in front of the rivet line on the underside of the elevator spar, at a spacing of 30 mm. The curvature of the elevator increases at this point, and basically you are just trying to get the VGs as far forward as possible.

I just flew the Zenith Aircraft demo 801 a week ago with your VG's installed on the elevator. With the original, short horizontal stabilizer and elevator and your VG's, there is no need to get the new longer stabilizer and elevator to get the control authority needed for slow landings. For heavier auto installations they still recommend the longer stabilizer and elevator. Piloting skills may vary.

Rich

I too have replaced the slats on my 801 with Stolspeed VGs and concur with Bill that they will probably never go back on. I haven't measured takeoff and landing distances but find Bill's results very believable. You do not give up much in STOL performance but definitely get another 5-10 mph at the top. My wife also flies the plane and prefers it in this configuration.

Bob & Karen, Colorado, USA

Thank you very much for working through slats and VG's. I removed the slats and flew the 801 and increased 8 mph in cruise, pushed the nose down, and did not have a dead stick feel. My landings, I actually have a flare! I have not received the main wing VG's yet, but I am very excited about the outcome at this time. The VG's should improve overall control. I will let you know.

Thanks again for your experimenting. After several years of flying the 801, the right answer has come. Just an update, and you know this already, I have installed the main wing VG's and rotation at takeoff is smooth. I can do a flare without power and land soft and in control. Slat brackets coming off.

Glen

Flight Testing

I finally got around to measuring my takeoff and landing lengths with and without slats.

Conditions:
Temp 54 F, DP 52 F, Alt 29.78, Wind 5-7 MPH headwind
Weight 1690 lbs, Lycoming O-360 burning super unleaded, 82" long, 40" pitch prop.

I got 4 tries:

With slats and Stolspeed VGs:
Takeoff – Landing
165' – 290
150 – 290
165 – 270
175 – 270
Average: 164 – 280

No slats, just  VGs:
Takeoff – Landing
220 – 320
200 – 258
190 – 285
220 – 310
Average: 207 – 293

If I can convince my wife that flying without slats is OK, my slats are for sale.

Bill, Alaska, USA