VG's on leading edge cuff

[750XL]

Hi guys,

Recovering my PA-20 and will be installing the crosswind stol leading edges. Is there a jig available to help find the right placement for the new leading edge?

Also, would like to buy bigger tail feathers. What`s the biggest that would fit and work well? I'm in Canada and owner maintenance so don't need an STC.

Thanks

[bob turner]

Did you mean to mention VGs? If so, who is going to test compatibility between the two STCs? Sometimes they fight each other!

[Jerry Burr]

If you are using Micro Aero, use the templates that come with the kit. They will have the correct placement with or without the x-wind cuff. Jerry.

[Erik]

Jerry,

You are the great wing mod tester. Let us just call you THE WING MOD GURU. Anyway...

I put the Micro's on a stock wing'ed 18 at the locations Micro recommended (I used the template and a thread line). Tell me, where do you think I'll get the most benefit? Control responsiveness? Lower Stall speed? Nothing?

Right before I put on the VG's, I was loaded to gross (more load than I usually fly) and I was going into a short strip. I stalled prematurely/high and didn't quite catch it with power in time. I hit hard (my tire marks started 2' from the edge of the runway). I bent some bolts. It scared me and now I come in hotter than I should as a safety. Well, I put the VG's on and I've been practicing stalls at altitude and basically the nose will not break over. And there is not much of a sink rate either. Pull the power, pull the stick back to the seat and hold. It just sinks at a slow rate at the same attitude. Is that the VG's? I didn't do a before VG and after VG comparison.

It's going to be awhile before I come in real slow on approach again. So, if that's what VG's will do for me, I won't realize it until I feel comfortable again.

Thanks, Erik

[Scooter7779h]

I have a low-speed helicopter airspeed. I have checked it against my GPS groundspeed and it is fairly accurate down to about 40mph.

Heres a picture of a "hot" approach for me in 79H, indicating 42mph. Usally I am trying to hold 38 or so.

I have Madras tips, Atlee leading edge, -18 flaps and Mirco VGs. It won't hard stall like your experience in the -18, only mush some which you can arrest with gobs of power.

http://sparky.supercub.org/photopost...00&ppuser=1540

[bob turner]

Okay, so VGs are the subject. I have a friend with a Sportsman equipped 180 Cessna. He added Micro-VGs. The stock wing was the modern Cessna droop. The airplane was comfortable at 65 mph on approach in the stock config; with all the stuff it is comfortable at 70.

I talked to a couple of VG gurus a long time ago - they said that the Sportsman/ VG combo had not undergone flight testing, and that compatibility was the responsibility of the installer. One of my contacts said that probably the Cub Crafters VGs were a performance enhancer to the Sportsman; and that probably the Micro were not.

My original heartburn had to do only with location of the VGs - I figured that the increased chord ought to affect the location, and I inquired. That's when I found out that there is no certification required for multiple STCs on the same wing. Sort of puts you in the experimental category, while retaining a standard airworthiness ticket.

I'd put one mod on, then try it for a long time, then add the other and see what you get. I'd leave the C-180 with Cessna droop stock! Just an opinion.

[Yard Dart]

I thought slats or vg"s but not both ?

[Jerry Burr]

Hi Dart. Slats and V.G.'s are the best combo going. Wayne can show you where to place them. Jerry.

[Erik]

Jerry - don't forget about my question! Thanks.

[Jerry Burr]

Hi Erik. The long answer to your question has taken up miles of previous strings. In short Micro V.G.'s will allow the modified wing to achieve a higher AOA than a stock (non-vg) wing. (Spelled slower speeds) Where and how you choose to use that feature is up to you. They were also designed to be used with power and full flaps. Both for takeoff and landing. That they happen to give better aileron response at high approach speeds is just a spin off and was not a design criteria. Keep feeling your way along, and you will do fine.