It seems that all newbie 170 owners, perhaps all airplane owners follow the same trajectory. Dream about the bird, search for the bird, find the bird, buy the bird, modify the bird…
A few google clicks and you can find a litany of keyboard experts who can regurgitate a must-have list in under nine seconds. Extended baggage, 180 gear, V-brace, 180 horse… the list goes on and on.
For me, my bird was fortunate to have a great start being kitted out with tons of mods. The previous owner had already invested in a cuff, ADSB, GNS430, new interior, lady legs, dbl puck breaks, etc etc etc…
That said, one of the few things it was missing was VGs.
It’s hard for a new owner to parse what is good and what is bad. Certainly everyone seemed to tout their necessity, but were they really needed?
Now I come from the glider world, and it was there where I met VGs for the first time. Soaring for me was racing gliders. To win these races we fiddled with everything to make our birds aerodynamically as clean and efficient as possible. And for some of us one of those tricks was to glue a few VGs in well chosen places to reduce drag.
Reduce drag with additional bits sticking out in the breeze?
Well, VGs prevent the airflow from lifting off, or separating, from any (wing, tail, fuselage,…) surface and thereby creating huge pockets of turbulence, ie drag.
A typical region where separation frequently occurs is where the wing meets the fuselage. On some gliders a few carefully placed VGs create swirls big enough so that the flow stays attached.
The little bit of drag added by the VGs is more than compensated by avoiding a big bubble of turbulence.
On all other aircraft VGs are not so much about reducing drag. They’re about improving (aileron) control (mostly) and adding lift (a little) at high angle of attack.
The swirling air behind them remains attached further along the wing chord and so more of it hits the aileron.
More control!
The higher the angle of attack, the more this effect is noticeable.
As I mentioned, my 170 came with the Sportsman. I was already impressed by its slow flight performance… the stall behavior was insane…what stall? More like a mush.
Since most of my glider instructors were WWII pilots hardly any flight passed by without a little excitement. A few turns of a spin, a hammerhead, … so stalls don’t bother me. My past is all about coordination and energy management. In fact I really like the stall. I want to KNOW where the limits are, so I can work the wing to maximize performance.
In my short time flying the 170, I found that with the yoke way back, I could use the rudder to counter wing drop and turning tendencies and keep it mushing all the way down.
With some playful experimentation, I found that with rather pronounced aileron inputs in that mush, I could provoke a gentle wing drop. Ease up on the yoke a bit and the wing would fly again.
I had really started to fall in love with that 100 series NACA 2412 wing… but could it perform better?
Given my aerodynamic curiosity - and the many favorable reports - I decided to add VGs.

The install was pretty painless. Unlike it’s bigger brother the 180, the C170 install is a bit simpler as there are no VGs on the sides of the vertical stab. Measure out the landmarks, stick on the template, prep and paint the VGs, then glue em on with the provided locktite epoxy. Easy peasy.
Did anything change? Yes.
With the VGs installed, I was able to get “beyond” the mush. At a higher angle of attack I could induce a benign break, meaning that the nose would drop. With only the slightest easing up on the elevator she would fly again very quickly.
Some folks talk about VGs and “stall speed,” but it’s important to understand that VGs are not a “STOL” device per se… They don’t lower the stall speed. What VGs do is keep the controls “crisp” down low, which in short, give you more confidence and authority at slow speeds.
Another interesting observation I had was that with aileron input, just before the break the wing would drop faster than without VGs, however, as long as I kept the angle of attack in the mushy region I had full aileron authority, no wing drop. Pretty cool!
So was it worth it? I say yes. The VG’s on the elevator made for more pitch control a low airspeed, enabling higher angle of attack - and more control at slow touchdown speeds.
On the wing, they kept the stall behavior benign and gave more aileron authority.
Something gained and very little lost: I’m quite happy with my decision to go with VGs.
At the end of the day, I’d call them a win. Curious as to the experience of others?