Lot of discussion on this subject in the past. One fellow had a good idea of putting them on with double sided tape and then fly it to see if you like them or not. Ours ended up flying a bit slower with id say better roll control but it was an unusually nose high attitude I would never land at. This is a paste of my experience from a former post. Keep in mind all planes are different.
“I added VG’s during our restoration of a C-140 with an O-200. The plane behaves much different than before. During slow flight the plane has a very high nose high attitude up to stall. The stall itself has a much harder break than it did before, This goes for both power off and on. The plane does seem to fly 2-3 mph slower. Once the wing lets go, it lets go pretty aggressively (I flight tested it before VG’s were installed and it was the usual benign mush, buffett and mild break). The roll control at slow speeds is slightly better but you only notice it in that unusual nose high attitude. Even then you would have to have a bunch of hours to notice it is only slightly better than without VG’s. With 8.50x6.00 tires if you tried to 3 point it in a true FULL stall the tail would touch WAY before the mains. We have 29” Bushwheel tires now and it’s better but even at low speed on rollout even if you think the tail is done and ready to be down for good you hold full aft wheel and the mains will get light or come off ground (BTW I wheel land 99% of the time).
I can land shorter coming in full flaps just ever so slightly behind the power curve doing a tail low (almost touching ground first) touchdown. When the mains touch power idle, push nose forward to a zero or negative angle of attack while braking heavily and modulating the elevator to hold desired rollout attitude then slowly letting off brakes to lower tail easily. This puts more weight on mains to aid in braking as well. I have found this technique has better braking or slowing results on wet grass, mud and wet mud covered rocks than the 3 point landing. You still slide a bit but not as much as the three pointer. Not to mention you have better forward visibility on roll out and you also save abuse on that 70+ year old tail assembly (esp on rocks,logs etc.) This technique was taught to me 25 yrs ago by a fellow airtaxi pilot when I was being trained in a C-185/180. It has works for me in Supercubs as well. We still use our 140 to go to off airport places for hunting and fishing but those places are picked VERY carefully. If I need to go to more challenging areas I use a PA-18 with 35” tires.
I would have put those VG’s on with double sided tape during the test and taken them off after. Why? I feel that they really don’t make a big enough difference in handling characteristics. I have flown that plane for decades and know it inside and out. It flew just fine without them. BUT I permanently glued them on (After all they can’t hurt anything right?) so my lazy ass is leaving them on.
As far as STOL charctaristics...........it’s not a strong point for a 140. That being said there are a couple of guys up here that routinely go in and out of a 700ft sea level strip. Neither have VG’s but they both have big engines (O-200,O-290). You may land short, but you will be hard pressed to takeoff in the same distance(unless light and a huge headwind).
These are just my personal views as I can only speak for myself. We all fly our planes however we want and if that’s what works for us individually then that is what is important. That goes for any mods that one feels might enhance the safety aspect as well. Modify your plane as you want and be happy! Not many folks have that freedom to own a plane to do so.
Watch some YouTube videos from that Valdez flyin STOL competition. Most of those really short landings are wheelies.
Enough BS from me.LOL”
