Do vortex generators reduce drag?

CJones

CJones

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Just as the subject says - do vortex generators reduce drag?

As I understand it, their main purpose is to disturb the airflow over the top of the wing, helping to decrease pressure on the top of the wing. But do they decrease drag as well?
 
depends on if you are reading the sales brochure or not.

i think their main benefit is at the low end of the speed spectrum not the high end. better climb performance thanks to delaying flow separation.

i don't imagine that having more crap sticking up in the airflow would make you faster.
 
tonycondon said:
depends on if you are reading the sales brochure or not.

i think their main benefit is at the low end of the speed spectrum not the high end. better climb performance thanks to delaying flow separation.

i don't imagine that having more crap sticking up in the airflow would make you faster.
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I believe the VG's at the end of wing tips reduce drag due to better flow seperation where hig pressure, and low pressure come together. Dunno about the ones in board.
 
winglets are a whole nuther animal. they are useful for drag reduction but have to be pretty precisely tuned to be practical. its usually better just to add span and take the drag reduction from a higher aspect ratio. unless you have some reason for span limits like a wingspan limited racing class or airline gate sizes.
 
For my airplane the answer is yes. Even without the gap seals, the Free Bird was faster than most Cherokees with similar power, and almost as fast as ones with more.
 
tonycondon said:
depends on if you are reading the sales brochure or not.

i think their main benefit is at the low end of the speed spectrum not the high end. better climb performance thanks to delaying flow separation.

i don't imagine that having more crap sticking up in the airflow would make you faster.
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It's all at the low end. At least on my plane. Maybe the loss of a knot at the high end due to increased drag. Essentially imperceptable at the high end, but very noticible at the low end. I don't do full-power on stalls any more as the nose-up angle gets too high, and I've taken slow flight so low that ATC asked what I was doing with zero groundspeed.

It's well worth the imperceptable loss at the high end.
 
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Do you gain all that much, enough to warrant the cost, and the PIA washing and waxing? Another way, are they worth it?

John
 
John Baker said:
Do you gain all that much, enough to warrant the cost, and the PIA washing and waxing? Another way, are they worth it?

John
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For me, yes. They saved my bacon at least one time. YMMV.
 
John Baker said:
Do you gain all that much, enough to warrant the cost, and the PIA washing and waxing? Another way, are they worth it?

John
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depends on what the climb performance is worth to you.

On the 421 the VGs were good for 120lb gross weight increase as well as a reduction in Vmc. Both good things and it didn't really hurt the top end speed too bad that we could tell. we weren't running book power setting anyway.
 
John Baker said:
Do you gain all that much, enough to warrant the cost, and the PIA washing and waxing? Another way, are they worth it?

John
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One of my CFIs put them on his C310 and it put the Vmc below the stall speed. I think that is definitely worth it.

For those of use with Cherokees that handle just fine at slow speeds and have a most benign stall, meh :dunno:. I guess it'd be fun to fly really slow, and it would take some wear and tear off of the landing gear, but you'd be hard pressed to make the cost back.
 
COFlyBoy said:
For those of use with Cherokees that handle just fine at slow speeds and have a most benign stall, meh :dunno:. I guess it'd be fun to fly really slow, and it would take some wear and tear off of the landing gear, but you'd be hard pressed to make the cost back.
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Drag reduction reduces the power required to maintain climb speed. That power then goes into rate of climb. A heavy Cherokee 150, on a hot day needs all the climb help it can get.
 
VG's clearly add drag and take a few knots off of top speed, but their advantage is especially clear for twins, where Vmc can get lower than Vso. Also can add a lot weight to max gross, depending on STC.

Advantages less clear for low powered singles.
 
flyingriki said:
Cool, but we were talking powered.....;)
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my point was a 30K foot altitude record is not very impressive to me when craft have flown higher with no power at all. I'm sure it took a lot of work, research, and effort for that guy to get his Long-EZ up that high and that is cool.
 
tonycondon said:
my point was a 30K foot altitude record is not very impressive to me when craft have flown higher with no power at all. I'm sure it took a lot of work, research, and effort for that guy to get his Long-EZ up that high and that is cool.
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Does make one wonder what a powered plane could do with mountain wave.

Trick becomes getting the engine to be more than balast at those altitudes:hairraise:
 
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