Q

questair

Member
Does anyone have experience with VG's on their 9's or for that matter 6's, 7's or 8's? Not that we probably need to reduce landing or stall speeds, but it might make an off airport experience a bit better if we could slow the plane down that little bit more.
 
Vso on my 9A is less than 50 mph IAS, probably closer to 45. Add power and you can almost hover to a landing. How slow ya wanna go?
Steve
 
I like them

I have some on my -4. I'm not sure how much they reduced the stall speed but they made a huge difference on the approach to the stall. The airplane feels much more solid at slow airspeeds. They allow you to feel more comfortable when flying at slower airspeeds. You need to remember that when flying with them because the airplane feels solid right up to the stall. You don't get the sluggishness and mushiness to let you know how slow you are flying. I added them to get into a small strip. With them I comfortably approach at about 60 MPH indicated. I know that is slow but you just have to be aware of how close to the stall you are and not ask the wing to do things it can't. BTW, probably lost a knot or two on the top end.
 
I'm not flying my -9 yet but from what I have heard from other -9er's is that the ailerons stay quite responsive right down to the stall.
 
VGs

I asked Vans about these a few years ago when I was building. They stated they would not offer any improvement due to the wing design.

Stall speed is down in the mid-40's so I would question just how much better, if at all, they can make things.

Keith
RV9A
 
VG's on RV-9's

Everything I have read and heard about our "9" airfoil has been really positive so I have my doubts that VG's would help it much. After mine is flying I think I will test them on the horizontal stab at some point though to see if that area can be improved on in anyway.

Doug Lomheim
90116, Finishing...someday.
 
No Free Lunches

If you choose to slap on some VG's I believe you should be asking yourself a question...Do I want to give up max crusie speed for a lower Vso? VG's are parasite drag and drag eats speed. So with some of the good comments already given, what is your ultimate desire...you will give up one for the other.
Dan B
Mesa, AZ
 
Regarding VG Trade offs, etc.

For me I would install them simply because I don't mind "experimenting" (ie. I'm installing a Mazda 13B rotary engine in my 9A and also built my fuel tanks with fire suppresant foam). Since it appears no one has installed them on a flying "9" yet, I'm still curious if they would further improve the low speed handling; and if so, what would the cost be on the top end.

The VG's can be initially installed with two sided tape so if they don't work they can be removed and stored with other parts and pieces I have already experimented with and rejected over the life of my project. :)

dl
 
I would be more than willing to try Vg's. I have a pretty straight and well constructed -9a by an AME, and it seems to have the elevator stall slightly before the wing. Elevators on low-wing aircraft tend to live in a very turbulent airflow, and anything that will keep the flow attached would be a good thing, both for elevator and rudder authority.
For me, it's not how slow do you want to go, it's having a margin of safety when the headwind suddenly goes away below the trees, and you are sinking toward the ground. I'll take another 5 knot margin of flying speed any day over 2 knots of top end.....you can get that back by waxing! ( the plane, guys!)

Perry
 
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