The International Cessna^® 170 Association

I recently purchased a 53' 170B with the Sportman's and VGs. It's apparent after flying it a lot this summer that the V-speeds published in the POH don't make sense. I was wondering if Stene has published updated V-speeds? Or if there is another resource?

Thanks so much for your time!
- Nate in Anchorage

Most mods such as this only offer “meets or exceeds” previously approved/certified performance. They do that to avoid certification expenses and potential controversy. (and it make for better marketing claims)

Your existing instrumentation is likely in need of re-calibration when such mods are completed if minute or incremental performance increases are expected. For that reason most comments by owners who have accomplished it make anecdotal claims that are difficult to reproduce.

Enjoy what it does do!

Have fun being a test pilot and gathering data! Several of my flights when I bought mine was flying patterns for average groundspeed=true airspeed and seeing what indicated was and working a stall speed/approach speed from that. Gives you a good excuse to go flying!

Stene used to publish the test data on their website for a 170B but no longer seems to have it. Its posted on the seaplanes north site. I've attached a screenshot.
I installed a sportsman and an 8042 prop this year. It makes a remarkable difference in short field performance. I wanted to do one and then the other so I could measure the performance difference from only the cuff but I got a little carried away.

Anywho... I try for 60 over the fence and 40-50 near the numbers. I find it much easier to land if I carry a bit of power. I suspect that the 8042 is working as a better airbrake/not generating the same amount of idle thrust as my old cruise prop. I've only got 25 hours on the setup so far. I can certainly get it in and out MUCH shorter than stock. That said my stock wing landings were much prettier. Esp in a cross wind.

Well…it appears to me that the Sportsman folks have skewed the data to their advantage.

The flaps up stall speed of a 170B is not 60… UNLESS you place it in a 20-degree bank!


And the top cruise speed at 7500’ is not 121…it’s 126….and so on and so on.

They can claim whatever they want because no two airplanes are identical or flown under identical conditions using identical techniques…. Cessna VS Sportsman…. both of whom are promoting their own product…the Difference being that Cessna had to document it to FAA standards…and Sportsman did not…. they only had to meet the claim that it did not “detract” from factory performance.

GAHorn wrote: ↑Sun Sep 22, 2024 2:30 am Well…it appears to me that the Sportsman folks have skewed the data to their advantage.

The flaps up stall speed of a 170B is not 60… UNLESS you place it in a 20-degree bank!


IMG_3126.jpeg


And the top cruise speed at 7500’ is not 121…it’s 126….and so on and so on.

They can claim whatever they want because no two airplanes are identical or flown under identical conditions using identical techniques…. Cessna VS Sportsman…. both of whom are promoting their own product…the Difference being that Cessna had to document it to FAA standards…and Sportsman did not…. they only had to meet the claim that it did not “detract” from factory performance.

Regardless, of the technicalities and minor airspeed discrepancies. It obviously makes the C-170 a much better performing airplane. It may not be necessary for how 95% of the owners fly their airplanes, but for those that really max perform their planes or want a larger safety margin. The Sportsman is a game changer.

I have a 53' with a sportsman. I installed the VG's at one point but removed them as they actually hindered my performance.

Can't honestly tell you what my numbers are because I haven't looked at my airspeed indicator in the last 600 hours or so. I can tell you that I takeoff and land in about 150' at sea level. The engine I've got helps with that on takeoff, but the landing is 100% due to the sportsman.

Hawkwagon,
Please indicate what your speeds are in all phases of flight in Knots please. I know others have indicated their speeds but your speeds are important also . I found the VG kit a terrible choice . There wasn’t a smooth transition of flight at all. On landing the tail suddenly dropped when doing a wheel landing . The VG,s lasted about 10 hours and about 7 landings. What a waste of money. Why did I buy them ,?? [out in the sun too much]. And the effort to fit them ?? what a waste of time .