vortex generators
- Thread starter tempdoug
- Start date
Jerry Burr
MEMBER
Sedro Woolley, Washington.
V.G.'s
Hi Tempdoug. Keep looking. It's ALL covered in other threads.
Jerry.
Hi Tempdoug. Keep looking. It's ALL covered in other threads.
Jerry.
murph
Registered User
Rotan, TX.
I've had BLRs for about 2 yrs and can't imagine flying without them anymore. Plane hangs in air at about 25 indicated with good roll authority. I can literally helicopter it straight down from about 500 ft. with a little headwind and then add a little power for flare. Takeoff is still limited by the tailwheel bouncing along while the mains are off the ground. I hope my new extended gear will get me some more AOA to help with that. The BLRs are the best performance mod that I've put on my -18. The Borer prop doesn't even come close. They also give me lots of peace-of-mind when my 17-yr-old son is out flying. You can grudgingly whip it up into a stall, but you can't do it inadvertently. It won't break, it just mushes. The strakes are a little bit unhandy when manually moving the plane. I think I'll add another set of handles to cure that. I can't speak at all for the Micros.
Hope this helps.
murph
Hope this helps.
murph
generators
murph i have had no experience flying with them. what im actually trying to figure out is the pieces longer shorter taller smaller placed different from one to the other after reading all the posts on these things the blrs sound like the way to go for a personal preference on the type of flying i want. but when i look at different planes i have no idea how to tell which is which
murph i have had no experience flying with them. what im actually trying to figure out is the pieces longer shorter taller smaller placed different from one to the other after reading all the posts on these things the blrs sound like the way to go for a personal preference on the type of flying i want. but when i look at different planes i have no idea how to tell which is which
CubCouper
Registered User
Sheridan WY
Easiest way to tell the difference is to look on the side of the fuselage near the back under/in-front-of the horizontals stabs. If the is a pie-tin size piece of sheet metal above the hand hold, its a BLR installation. That's the "strake" they're talking about. Find VG-equipped cubs with and without the strake and compare... the rest of the differences are subtle, visually at least.
I guess I'm a skeptic about the VG's. I have heard the stories before about "helicoptering in" but one experienced bush pilot friend who made that claim couldn't get into my hunting camp, which is a bad bad place, and get stopped any quicker than I did without the VG's (I honestly don't remember which type he had).
I just don't see how the tail could fly adequately at 25 mph, especially loaded. Could it be that the angle of attack is just different enough to make the airspeed read wrong?
Another neighbor has the BLR VG's on his Cub and he told me he wished he had never installed them.
It would be nice if all the hype were true but until some better proof is posted, I wouldn't fight these buggers, with my wing covers and lifting the tail around on skis, for them.
On the other hand, I have seen proof of improved performance with a Borer prop.
I just don't see how the tail could fly adequately at 25 mph, especially loaded. Could it be that the angle of attack is just different enough to make the airspeed read wrong?
Another neighbor has the BLR VG's on his Cub and he told me he wished he had never installed them.
It would be nice if all the hype were true but until some better proof is posted, I wouldn't fight these buggers, with my wing covers and lifting the tail around on skis, for them.
On the other hand, I have seen proof of improved performance with a Borer prop.
Jerry Burr
MEMBER
Sedro Woolley, Washington.
V.G.'s
Hi Cubdriver. I love a good skeptic. Is there any way you could find out what brand of V.G. that your experienced Bush pilot friend was using? I would really like to know. As for the tail flying at 25mph, just think about it. I can lift my tail sitting still with the brakes locked and a shot of power. Most anytime that you are flying at 25 the prop is blowing the tail, and it is not a problem. Also you talk of posting proof. I don't know what else you want. I have 173 pages of data in a folder that if copied would plug this site worse than the accident record on the raves thread. Tell you what. Instead of me plugging this site with stuff that most people don't want to read anyway, why don't you e-mail Chuck White at microaero.com and tell him you want to test a set of his V.G.'s. If you want you can just tape them on for your test. If you are not 100% satisfied just send them back for a complete refund. I guarntee it. Jerry.
Hi Cubdriver. I love a good skeptic. Is there any way you could find out what brand of V.G. that your experienced Bush pilot friend was using? I would really like to know. As for the tail flying at 25mph, just think about it. I can lift my tail sitting still with the brakes locked and a shot of power. Most anytime that you are flying at 25 the prop is blowing the tail, and it is not a problem. Also you talk of posting proof. I don't know what else you want. I have 173 pages of data in a folder that if copied would plug this site worse than the accident record on the raves thread. Tell you what. Instead of me plugging this site with stuff that most people don't want to read anyway, why don't you e-mail Chuck White at microaero.com and tell him you want to test a set of his V.G.'s. If you want you can just tape them on for your test. If you are not 100% satisfied just send them back for a complete refund. I guarntee it. Jerry.
Jerry Burr
MEMBER
Sedro Woolley, Washington.
Borer.
Sorry Cubdriver. I got in a hurry. I forgot to ask, How much slower can you land with the Borer prop that you installed? Thanks. Jerry.
Sorry Cubdriver. I got in a hurry. I forgot to ask, How much slower can you land with the Borer prop that you installed? Thanks. Jerry.
S
StewartB
Jerry,
If this has been addressed before, forgive me. Does your data include testing either or both brands of VG's at gross wt.? Is the performance curve different when mapped from light to heavy with Micro's or BLR's? My desire for improved performance is biased toward flying heavy. I'm also interested in your criteria for testing. Straight and level stalls vs. steep turn stalls, etc. How about your mod wings vs. stock wings? Forward and aft CG limits? Or pa18 performance enhancement vs. pa12? My questions are based on curiosity AND what I'll want on my 12, which will fly at gross much of the time. Thanks in advance.
SB
If this has been addressed before, forgive me. Does your data include testing either or both brands of VG's at gross wt.? Is the performance curve different when mapped from light to heavy with Micro's or BLR's? My desire for improved performance is biased toward flying heavy. I'm also interested in your criteria for testing. Straight and level stalls vs. steep turn stalls, etc. How about your mod wings vs. stock wings? Forward and aft CG limits? Or pa18 performance enhancement vs. pa12? My questions are based on curiosity AND what I'll want on my 12, which will fly at gross much of the time. Thanks in advance.
SB
cubdrvr
SPONSOR
YKN(mother city of the dakotas)
I have never used VG's on any of my cubs ( been flying them since the 60's) until the past 2 years. I installed a set of Micros when I redid my cub and, next to the Borer, is the single most important and effective modification that I have done. I wish they would have been available when I was spraying with cubs. I have found my cub to be much more docile and controllable at slower airspeeds.......all I can say to you non-believers is to give 'em a try.....you will like them.
Gary Reeves
SPONSOR
Lake Clark National Park, Alaska
VG's
I don't have the ones Jerry tested, but I do have the BLRs. I'd guess that no one should be disapointed with either. I was a skeptic from about 30 years in the aviation industry, but once I flew a cub with them, there was no going back. They provide so much margin and control at low speed on and off.
I was sent a great idea on how to install a set for on/off comparisons and have talked a friend into doing this with the micros. He probably won't do it until next spring.
Put on a set and you will have to redine stall and stall speed. Mine moved a full thumb with below the previous airspeed - about 8 to 10 mph. It is so remarkable to be out of airspeed and notice that the SC still responds to the stick.
I would never have a Super Cub without them and would buy sets for close friends.
Gary
I don't have the ones Jerry tested, but I do have the BLRs. I'd guess that no one should be disapointed with either. I was a skeptic from about 30 years in the aviation industry, but once I flew a cub with them, there was no going back. They provide so much margin and control at low speed on and off.
I was sent a great idea on how to install a set for on/off comparisons and have talked a friend into doing this with the micros. He probably won't do it until next spring.
Put on a set and you will have to redine stall and stall speed. Mine moved a full thumb with below the previous airspeed - about 8 to 10 mph. It is so remarkable to be out of airspeed and notice that the SC still responds to the stick.
I would never have a Super Cub without them and would buy sets for close friends.
Gary
Dave Calkins
Registered User
Anchorage, Alaska
No fabric cutting.
Just holes in the fabric to accept the screws that go through the strakes, then into the adel clamps that are on the fuselage structure.
The guys that complain about the strake being in the way for ground handling must have really heavy tails, 'cause mine is pretty heavy and I never even bump into the strakes. That's just not an issue.
This does not mean that I think the BLR kit is the only way to go. I own a Micro VG kit as well, and it works great.
Dave.
Just holes in the fabric to accept the screws that go through the strakes, then into the adel clamps that are on the fuselage structure.
The guys that complain about the strake being in the way for ground handling must have really heavy tails, 'cause mine is pretty heavy and I never even bump into the strakes. That's just not an issue.
This does not mean that I think the BLR kit is the only way to go. I own a Micro VG kit as well, and it works great.
Dave.
tempdoug, go to djfraudmans excellent site where you can view pictures of the BLR installation.
Vidir
http://home.earthlink.net/~djfraudman/supercub/supercub.html
Vidir
http://home.earthlink.net/~djfraudman/supercub/supercub.html
Steve Pierce
BENEFACTOR
Graham, TX
i had a question for some people that make experimental generators heres how it turned out ive never flown a plane with them and have had no experience with them so before i spend the money just need some ideasDo you guys make a full generator like the one in the picture but without the taper cut off for our slower
stalling airplanes then I would be interested.
---------------------------------------------------------
You have been given incorrect information. What you are requesting is that we take a superior product and
reduce to something inferior. We have been manufacturing Vortex Generators since 1985.
The Vortex Generators we manufacture were developed in the wind tunnel at Ohio State Univertsity by Aero-
Space researchers working closely with John Rontz. Mr Rontz is the same a Rontz who designed so many
airfoils for use by Burt Rutan. Both Rontz and Rutran are recognized authorities in the field of aerodynamics.
The Delta shape generaters as much boundary layer activity as the flat plate. The flat plate, however,
generates three times the drag coefficient and results in lower speeds when installed. Furthermore, the Delta
design generates lift vectors that result in a boundary layer helix. That is what you want. That is ALL you
want.
Flat plates generate turbulence and while this too energizes the boundary layer, the unnecessary disruption of
the streamline above the boundary layer is what is costing you drag.
The reason the flat plate has become popular is simply because of economy of production: it's cut from
analuminum "T" or "L" sectioned extrusion. It's simply too costly to replicate the Delta shape using extruded
material. Each would require expensive machining. So, they simply cut off a section of it and leave it at that.
There's also no camber to the bottom of their device so it really doesn't fit the contour of the airfoil at all. This
raises the profile further. Ours are injection molded and can be attached with conventional adhesvies to fabric
covered airplanes. Aluminum can not.
Whomever suggested that Vortex Generators were speed, airfoil or aircraft specific also gave you missleading
information. Vortex generators are generic devices and work exactly the same way regardless of the speed of
the machine and regardless of the airfoil or aircraft on which they are used.
Our VG's are used on thousands of aircraft around the world at speeds from 35 mph on up. Bush pilots in
Alaska, cattle herders in the Australian Outback. Doctors flying medical care in remote parts of Africa. What
are you flying that flies slower than that?
We urge you to visit our website at:
http://www.computer-certainty.com
Thanks for writing CCI.
stalling airplanes then I would be interested.
---------------------------------------------------------
You have been given incorrect information. What you are requesting is that we take a superior product and
reduce to something inferior. We have been manufacturing Vortex Generators since 1985.
The Vortex Generators we manufacture were developed in the wind tunnel at Ohio State Univertsity by Aero-
Space researchers working closely with John Rontz. Mr Rontz is the same a Rontz who designed so many
airfoils for use by Burt Rutan. Both Rontz and Rutran are recognized authorities in the field of aerodynamics.
The Delta shape generaters as much boundary layer activity as the flat plate. The flat plate, however,
generates three times the drag coefficient and results in lower speeds when installed. Furthermore, the Delta
design generates lift vectors that result in a boundary layer helix. That is what you want. That is ALL you
want.
Flat plates generate turbulence and while this too energizes the boundary layer, the unnecessary disruption of
the streamline above the boundary layer is what is costing you drag.
The reason the flat plate has become popular is simply because of economy of production: it's cut from
analuminum "T" or "L" sectioned extrusion. It's simply too costly to replicate the Delta shape using extruded
material. Each would require expensive machining. So, they simply cut off a section of it and leave it at that.
There's also no camber to the bottom of their device so it really doesn't fit the contour of the airfoil at all. This
raises the profile further. Ours are injection molded and can be attached with conventional adhesvies to fabric
covered airplanes. Aluminum can not.
Whomever suggested that Vortex Generators were speed, airfoil or aircraft specific also gave you missleading
information. Vortex generators are generic devices and work exactly the same way regardless of the speed of
the machine and regardless of the airfoil or aircraft on which they are used.
Our VG's are used on thousands of aircraft around the world at speeds from 35 mph on up. Bush pilots in
Alaska, cattle herders in the Australian Outback. Doctors flying medical care in remote parts of Africa. What
are you flying that flies slower than that?
We urge you to visit our website at:
http://www.computer-certainty.com
Thanks for writing CCI.
Optimal vg planform is neither rectangular or triangular (delta-shaped). It is parabolic. Looks a bit like a trapezoid with a crescent snipped out of the front. The short delta vg's will work fine, but will need to be located further forward than the taller vg's and might require a larger number of devices.
TempDoug, just visualize the semi-span planform of the McDonnel-Douglas BWB (p.s. I don't know how to spell McDonnel).
Our planes are draggy enough that the planform doesn't make any significant difference to our performance, so long as the vg's are tall enough to stick up about 20% of their height through the boundary layer. Shorter vg's have to be located further forward than tall ones. I kind of like the ones that Jerry uses.
Our planes are draggy enough that the planform doesn't make any significant difference to our performance, so long as the vg's are tall enough to stick up about 20% of their height through the boundary layer. Shorter vg's have to be located further forward than tall ones. I kind of like the ones that Jerry uses.
FlipFlop
Registered User
Maintaining at Flight Level Zero, requesting lower
Tim said:
Tim...
You have to figure it out yourself... They give you some guidelines, but it's not enough info... I ended up with 34 VGs on each wing and I didn't install any in the tank area so I don't knock 'em off with a gas can... I set the VGs at 20 degrees and I can't remember the distance apart...
There are some excellent pictures of VG installations in the SC.org picture files... There's plenty of Cubs around with VGs to look at for ideas... I'm probably going to catch flack for saying this, but I think my installation is pretty close to MicroAero's...
I haven't had the opportunity to do any serious comparison flying yet, but what I have done indicates an obvious shorter takeoff roll, steeper climb angle and approximately 4-5 mph less approach speed...
MAJOR disclaimer; as an EXPERIMENT, I installed these EXPERIMENTAL VGs on an EXPERIMENTAL airplane in an EXPERIMENTAL manner...
Steve Pierce
BENEFACTOR
Graham, TX
Coming from a true EXPERIMENTER. Did you experiment in your younger days?
Steve Pierce
BENEFACTOR
Graham, TX
Micro sells a kit for experimentals for $395 and I think it comes with templates.
