I’m flying a 1967 172H with a S/M STOL kit, do any of you have experience with VGs on the horizontal stab, have you tried VGs at the trim tab? The aircraft is a bit nose heavy and could use a little more trim athority. And how much of a difference is there when used on the vertical and horizontal stab? Is it noticeable?

After flying my 801 for 7 years that has the early model "small tail" I installed the VG's on the elevator this last annual... HUGE difference... I figured the VG idea was mostly snake oil BS... I was wrong......

I can't comment on them on the tab itself but I also noticed a huge difference when I put them on the bottom of my horizontal. I used to have a pristine 182 that hangared with us and it had the VG's on the top of horizontal. The other day I saw him sanding on his tail. Turns out the airplane went through 5 annuals before anyone realized they were on wrong all that time. Wonder what he paid for that snafu.

AvidFlyer wrote:I can't comment on them on the tab itself but I also noticed a huge difference when I put them on the bottom of my horizontal. I used to have a pristine 182 that hangared with us and it had the VG's on the top of horizontal. The other day I saw him sanding on his tail. Turns out the airplane went through 5 annuals before anyone realized they were on wrong all that time. Wonder what he paid for that snafu.

He paid a bunch
I was the one that pointed it out.

I figure that the VGs for the trim tab would go on the top of the elevator just in front of the trim tab.

Maybe it'd be wisest to put them where the manufacturer said works best.....just a thought.

MTV

AvidFlyer wrote:I used to have a pristine 182 that hangared with us and it had the VG's on the top of horizontal. The other day I saw him sanding on his tail. Turns out the airplane went through 5 annuals before anyone realized they were on wrong all that time. Wonder what he paid for that snafu.

I almost feel sorry for your buddy, almost...
Sorry but that is just too hilarious, 5 years you say??!

Battson wrote:

AvidFlyer wrote:I used to have a pristine 182 that hangared with us and it had the VG's on the top of horizontal. The other day I saw him sanding on his tail. Turns out the airplane went through 5 annuals before anyone realized they were on wrong all that time. Wonder what he paid for that snafu.

I almost feel sorry for your buddy, almost...
Sorry but that is just too hilarious, 5 years you say??!

I feel sorry for him, but what about the goof that put them on top? He should be footing the paint bill. Apparently the IA who's been signing it off all these years has never seen a set installed?

Apparently the IA who's been signing it off all these years has never seen a set installed?

...or just pencil whipped the owner's "annual".

Cary

Of all the performance add on's you can buy for aircraft, I gotta say the VG's have the biggest bang for the buck. They continuously impress me how they can de-nastify quirky experimental wings, as well as remarkable improve controllability at slow speeds. I was so impressed that, as a distance runner, I stuck them to my forehead and gained an extra 23 minutes of stamina. My wife said I should try them on my ..um you know what, but quickly changed her mind when she discovered they where too painful.

L-19 wrote:Apparently the IA who's been signing it off all these years has never seen a set installed?

Or bothered to understand how they work...

" Whattaya mean they don't go on the top??? "

mtv wrote:Maybe it'd be wisest to put them where the manufacturer said works best.....just a thought.

MTV

Is there a VG manufacture that recommends or uses VGs for the trim tab? Is there a reason that they won’t work there?

I'm sure they would work find there.... But whats the purpose? You think your experiencing air separation on your trim tab? I would think putting them UNDER the horizontal would fix your problem, but I havent heard of a kit for just the tail? Better elevator effectiveness would mean using less trim than you are using currently correct?

I have a brand new set in a box in the hangar, waiting to go on my GCBC as soon as it's on land. From all reports I've heard it will make a noticeable improvement.

L-19 wrote:I'm sure they would work find there.... But whats the purpose? You think your experiencing air separation on your trim tab? I would think putting them UNDER the horizontal would fix your problem, but I havent heard of a kit for just the tail? Better elevator effectiveness would mean using less trim than you are using currently correct?

I have a brand new set in a box in the hangar, waiting to go on my GCBC as soon as it's on land. From all reports I've heard it will make a noticeable improvement.

It a possibility, the trim becomes less effective at lower speeds, I was thinking that there may be separation there, I never run out of elevator, but if I use all of my trim its still not enough, and it approaches unmanageable on a go around, I realize that I’m trying to compensate for a forward CG. I was curious if anyone had tried it and if it made a difference or not. And how effective are they on the rudder? Will I be able to get more yaw on a slip? Ultimately a proper CG is the answer.

172heavy wrote:It a possibility, the trim becomes less effective at lower speeds, I was thinking that there may be separation there, I never run out of elevator, but if I use all of my trim its still not enough, and it approaches unmanageable on a go around, I realize that I’m trying to compensate for a forward CG. I was curious if anyone had tried it and if it made a difference or not. And how effective are they on the rudder? Will I be able to get more yaw on a slip? Ultimately a proper CG is the answer.

What type are you flying in this case?

but if I use all of my trim its still not enough, and it approaches unmanageable on a go around,

Not sure I'm following this. My P172D is a bit nose heavy, too (Lycoming conversion), and full aft trim is not quite enough if I'm trying to maintain a very slow airspeed approach, like 55 mph. But that just means I have to have some back pressure on the yoke. If I have to go around, I have to shove the yoke and retrim right away--but I don't think that has a thing to do with any separation at the trim tab. I think it just means that the tab is at its lower limits in its effort to raise the elevator (tab goes down, elevator goes up). On the go around it's necessary to overcome the tab's efforts by shoving the yoke forward and retrimming to avoid a "trim stall"--and if the tab was more effective, it would require just that much more of a shove and quicker retrimming. All of this is normal, in any airplane that uses a tab for pitch trim; adding VGs to the tab alone, if it did anything at all, would exacerbate the effects of trimming and increase the need to shove hard and retrim on a go around.

Again, best to put the VGs where the manufacturer says, unless you're interested in becoming a test pilot.

Cary

I never run out of elevator, but if I use all of my trim its still not enough, and it approaches unmanageable on a go around

If you really need more AFT elevator authority on a tail with a trimtab, you'll want full "NOSE DOWN" trim set.

Sounds counter-intuitive, but it sets the tab way up high, and give you a bit more ooomph when you pull back.

Gump

Like GUMP said, you use the trim tab as a flap. For the elevator!!!

I never run out of elevator, but if I use all of my trim its still not enough, and it approaches unmanageable on a go around


If you really need more AFT elevator authority on a tail with a trimtab, you'll want full "NOSE DOWN" trim set.

Sounds counter-intuitive, but it sets the tab way up high, and give you a bit more ooomph when you pull back.

Gump

I put VG's on my 1976 172M. They made a definite noticeable difference. Now have a '64 172E and am considering adding them on it as well.