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Vortex Generators

A

ALMARTON

Well Known Member
Hi folks!

Does anyone use or have knowledge/experience on Vortex Generators with RV's?

Those from the link are said to lower the stall speed up to 9mph!!

http://www.stolspeed.com/

I am considering using it, but have some doubts/questions;

- Would it affect cruise speed?:confused:
- Is it as good as they say? :)

Does anyone have opinion based on experience on that?

Thanks in advance;:cool:

Alexandre "neck" Marton
(Brazil)
 
Do a "search"..

This has been discussed ad nauseum on here.

My take...you only "ugly-up" the airplane, go slower and the rag gets hung up when you wash her:)

Best,
 
Alesandre:

I'm new to the RV world but I did notice a Florida builder who was exhibiting RV-9 aircraft at the recent Sebring LSA Expo who uses these on his 9's. He was building & selling 9's as LSA's (a shady fact that's a topic in itself...) and he claimed the VG's enabled the aircraft to stall at a speed low enough to meet the LSA rule. So perhaps that is one consequence of using them.

Jack
 
Hello Pierre and Jack!

Pierre you said it had been discussed here before, could you send me a link for the posts ?

Jack it would be nice to have a lower stall if it does not affect cruise and a bonus would be having the aircraft in the LSA category (but it is already that way here in Brazil !!! Thanks god and the Military, but now that we have a civil agency instead called ANAC that is the like of your's FAA they are trying to screw that freedom of us.... lets see...)

By now I am skeptic and tend go with Pierre idea that it sounds to good to be true.

Anyone having more info (experience) on that would be most grateful.

Regards
 
don't bother

I had them on my RV7. Little cruise speed decrease (maybe 2 kts). When I removed them I measured the stall speed as 1 kt faster.

Waste of time on a hershey bar wing.

Pain in the but to polish the leading edge.
 
Here's one...

...post from a while back:

http://www.vansairforce.com/community/showthread.php?t=49839&highlight=vortex+generators

Look at the top of the page and you'll see "SEARCH". Press the button and then type in 'vortex generators' and quite a few links will show up. All the RV's stall slowly anyway, very comparable to Pipers and most 4 place Cessna's that the weight, expense and ugliness just isn't worth it and I've been told that you lose several knots, not 1.

Best,
 
I used to fly a Cardinal and belonged to a Cardinal owners online group. Several owners who installed the VGs, reported a significant decrease (5kt) in stall speed with NO noticeable decrease in top end speeds. They were all pleased with the results and low speed handling. I'm sure correct placement is critical to results. You can't just buy some and stick them on without some serious testing. Bottom line, as others have said, the RV's handle nice at low speeds with an already low stall speed. I'm not sure that the effort would be worth the possible results.
 
VG's ...what do you really want?

Vg's are a favourite topic of mine..everything folks have said here is no doubt true in the instances discussed.
If you want to land slower, I think you need a lift reserve indicator, or more accurate ASI to know what speed you are really travelling.
the VG can provide a more solid 'feel' at low speeds, by keeping the flow attached, but I think it's fair to say that wing area X will give you Y lift at Z angle of attack. There is no free lunch.

the people who sell the VG's and a positioning template have done the testing for you, in most cases, and you can install them with some degree of confidence, and pay them $200 or more for this service.
still, you are now a test pilot of a different wing. Learning to fly my -9a with an instructor, we managed to experience a violent nose down pitch at stall in a certain configuration, ( which I don't remember, sorry) and this made me think that I'd like at least the our 1/3 of the wing to have VG's or other aids to keep that part of the wing, and the elevator, flying further into the stall.

some food for thought.
 
Clean Stall Reduction

A key point to consider is that the LSA performance standards mandate a maximum value for Stall Speed-Flaps Up.

There is some pretty good data in the archives from testing on an RV-6 that showed a 4 Knot+ Cleanstall speed reduction, with little additional reduction with half or full flaps.

Assuming that this is valid data, VGs may be a key factor in meeting the specific LSA standards.
 
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