Vortex Generators

[aviatoreb]

28 minutes ago, firelog1101 said:

It sounds like if there is a decrease it's <2 knots.  I've searched around the forum and haven't heard anyone who put them on saying they have seen even a 5 knot difference.  I could see <2knots being a pretty reasonable trade off for better slow flight characteristics.

Also I have a theory that unfortunately I never tested because I had VGs installed so early in my ownership.

TKS - which I have - already damages the flow and more so than VGs since they are on the bleeding front edge of the airfoil where we expect the boundary layer to be very thin.  So then that disturbed flow is already a bit disturbed and the VGs are not doing any further damage.  So that a VG + TKS plane may be no slower than a TKS only plane, even a VG and no TKS plane may be slower than a no VG and no TKS plane.

[steingar]

If you're routinely going into and out of tight spaces it seems like a real no brainer.  And talk about safety equipment!  The impact energy goes down with the square of the speed.  If you can lower your stall speed a few miles per hour that's a crapload less energy to displace should things go sideways.  And you've got complete control all the way into the stall, assuming you can still stall the aircraft (I couldn't stall my Cherokee without the nose up trim cranked to the stop).  

[aviatoreb]

2 minutes ago, steingar said:

...And talk about safety equipment!  The impact energy goes down with the square of the speed.  If you can lower your stall speed a few miles per hour that's a crapload less energy to displace should things go sideways.  

What a fun way of describing KE=1/2 m v^2 so kinetic energy is quadratic with respect to velocity. .. a crapload...  :-)

BTW another characteristic of VGs is that you much less so get soft near stall but it maintains some crisp control authority for a lot longer.

[paulsalem]

1 hour ago, aviatoreb said:

Also I have a theory that unfortunately I never tested because I had VGs installed so early in my ownership. 

Would you please send me a private message? I tried to send one to you but it said that you weren't able to receive them. Thanks. 

[ArtVandelay]

For non laminar flow, VGs or BLEs (boundary layer energizers) as Lear calls them can lessen drag, hence the dimples on a golf ball. Lear has them in front of the ailerons to improve aileron control. If you don’t see a speed decrease then there was some non laminar flow. Wing was dirty before you cleaned it to install the VGs, the stall strips trip the flow, and our man made sheet metal is far from perfect could be just a few reasons.
Personally I find them unsightly and don’t want to clean around them. But if I were to install them , it would only be in front of the ailerons.

[aviatoreb]

54 minutes ago, paulsalem said:

Would you please send me a private message? I tried to send one to you but it said that you weren't able to receive them. Thanks. 

Huh - that's strange - ok - here you go - PM sent.

[N9201A]

The most effective thing that VG's do is remove $1500-$2000 from your wallet which decreases your sink rate on short final.

And make it REALLY hard to wash and wax your wings...


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[aviatoreb]

4 hours ago, N9201A said:

And make it REALLY hard to wash and wax your wings...


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Hardly.   I have zero problem washing and waxing my wings.  And now that I am using the ceramic wax thing - it is almost trivial.  I mean don't get VGs for other reasons - you don't like the way they look, or an arguable but harder to prove reason like they hurt your performance to which I disagree.  But let's not make up false reasons like it makes waxing hard.  It takes me the same amount of time to wax my plane with and without.  And with the new ceramic wax stuff, it takes such a trivially short amount of time, and the result is so shiny fantastic, its not worth a blink of an excuse.

[PTK]

6 hours ago, N9201A said:

And make it REALLY hard to wash and wax your wings...


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They’re not needed and are ugly, but that’s just my opinion. The airplane has stall strips properly placed on the wings (closer to the root) whose purpose is to retain aileron authority in slow flight and higher AOA. When flown properly by a trained pilot it handles slow flight just fine w/o vg’s.

[aviatoreb]

1 hour ago, PTK said:

They’re not needed and are ugly, but that’s just my opinion. The airplane has stall strips properly placed on the wings (closer to the root) whose purpose is to retain aileron authority in slow flight and higher AOA. When flown properly by a trained pilot it handles slow flight just fine w/o vg’s.

Fair enough.  Beauty is in the eye of the beholder.

I find them to be beautiful as when I look at them I think of the science related to controlling the vorticity flowing over the wings.  I find science and carefully engineered machines to be beautiful.  This is an engineering trick in fluid dynamics and I find it beautiful because it is ingenious.

It is red herring to state something like "when flown properly by a trained pilot" ... fact: an airplane with vortex generators stalls at a slower speed than one without, and on the Mooney it is about 5kts.  I don't care how trained you or I am is as a pilot, or resorting to imply my pilot skills must be inferior if I like VGs - it is a fact that a trained pilot cannot make my Mooney stall slower with my VGs removed than I can with my VGs.  I was thinking of the safety factor of what if an off field landing and reducing kinetic energy when I had them installed and I am confident in this values based decision today ten years later.  We can argue what I value as important vs what you value as important as who's values are more important - but enough with the faux-facts red herring "When flown properly by a trained pilot.." diversion.  Just say your aesthetics and your choices as to how to engineer your flight envelope are your choice and no need to sink your discourse to insults of the pilot skills to those pilots that don't make the same choices as you.  Your diversions of insults are unbecoming.

Edited July 12, 2020 by aviatoreb

[PTK]

On 7/11/2020 at 7:59 PM, aviatoreb said:

Just say your aesthetics...

I beg your pardon Sir?! I made no reference to your skills, my skills or anyone else’s! I made no insults to you or anyone else! You’re out of line with your slander and baseless accusations. 
I stand by what I said. 
 

[aviatoreb]

1 hour ago, PTK said:

I made no reference to your skills, my skills or anyone else’s! I made no insults to you or anyone else! You’re out of line with your slander and baseless accusations. 
I stand by what I said. 

 

1 hour ago, PTK said:

When flown properly by a trained pilot it handles slow flight just fine w/o vg’s.

 

[N9201A]

Hardly.   I have zero problem washing and waxing my wings.  And now that I am using the ceramic wax thing - it is almost trivial.  I mean don't get VGs for other reasons - you don't like the way they look, or an arguable but harder to prove reason like they hurt your performance to which I disagree.  But let's not make up false reasons like it makes waxing hard.  It takes me the same amount of time to wax my plane with and without.  And with the new ceramic wax stuff, it takes such a trivially short amount of time, and the result is so shiny fantastic, its not worth a blink of an excuse.

Um, joking...

 

I’ve not installed VGs on my Mooney just because I’ve prioritized other things. But l have flown enough other high-performance aircraft to know VGs work, are absolutely worth the trade-offs (haven’t seen empirical, material top-end losses) and are the closest thing I’ve seen to “free performance” in aviation. And yes I’ve got some speed mods and the data supporting (or not) them. It’s self-evident that a VG-equipped wing will always outperform a “clean” wing in the slow flight regime, that’s aerodynamics.

 

That said, l don’t wash ‘em, either, just fly ‘em. The only aircraft I wash doesn’t have them. Glad to hear they aren’t a burden...I will get a set eventually.

 

Nice bird ...

[aviatoreb]

3 minutes ago, N9201A said:

Um, joking...

I’ve not installed VGs on my Mooney just because I’ve prioritized other things. But l have flown enough other high-performance aircraft to know VGs work, are absolutely worth the trade-offs (haven’t seen empirical, material top-end losses) and are the closest thing I’ve seen to “free performance” in aviation. And yes I’ve got some speed mods and the data supporting (or not) them.

That said, l don’t wash ‘em, either, just fly ‘em. The one I wash doesn’t have them. Glad to hear they aren’t a burden...I will get a set eventually.

Nice bird ...

Thanks.

Actually no kidding, its not hard to wax or wash with them.  The trick is to just move your cloth in s-shaped curves around the vgs moving quickly in-between them, swooping between one then the next then the next all the way along the wing in a smooth progressing motion and walking along.  It takes me no longer this way to polish between them than a different hand motion which is more the wax-on-wax-off motion described by Mr Miyagi that I use on the rest of the body of the wing.

Edited July 12, 2020 by aviatoreb

[PTK]

On 7/11/2020 at 7:59 PM, aviatoreb said:

Your diversions of insults are unbecoming.

You’ve had plenty of time to apologize but haven’t. And I didn’t expect you to, frankly.  

But I forgive you nevertheless. 

[mike_elliott]

On 7/8/2020 at 10:05 AM, firelog1101 said:

It sounds like if there is a decrease it's <2 knots.  I've searched around the forum and haven't heard anyone who put them on saying they have seen even a 5 knot difference.  I could see <2knots being a pretty reasonable trade off for better slow flight characteristics.

I have stalled a M20V with VG's at 52kts, 200 # under gross. Thats 7 kts less than book at full gross, and have stated that on Mooneyspace at least 2 other occasions. They work.

[ArtVandelay]

I have stalled a M20V with VG's at 52kts, 200 # under gross. Thats 7 kts less than book at full gross, and have stated that on Mooneyspace at least 2 other occasions. They work.

Have you tried them just in front of ailerons, stall speed may not be as low, but they should be benign.

[aviatoreb]

24 minutes ago, ArtVandelay said:

Have you tried them just in front of ailerons, stall speed may not be as low, but they should be benign.

The STC requires that one install the entire kit and exactly placed as they require.  They give you a template to lay out over the wing to glue on the parts.

[firelog1101]

1 hour ago, mike_elliott said:

I have stalled a M20V with VG's at 52kts, 200 # under gross. Thats 7 kts less than book at full gross, and have stated that on Mooneyspace at least 2 other occasions. They work.

Sorry I meant to say <2kts loss on cruise speed rather than stall speed.

[mike_elliott]

1 hour ago, ArtVandelay said:

Have you tried them just in front of ailerons, stall speed may not be as low, but they should be benign.

One doesnt have free choice of where they are positioned. Maxwell added them to the Mooney Ultra Acclaim right before the new owner picked it up in Kerrville where I transitioned trained him and his CFI, thus the opportunity to fly and stall it as configured according to the STC. 

[SCPDaddy]

On 7/11/2020 at 6:02 PM, aviatoreb said:

Hardly.   I have zero problem washing and waxing my wings.  And now that I am using the ceramic wax thing - it is almost trivial.  I mean don't get VGs for other reasons - you don't like the way they look, or an arguable but harder to prove reason like they hurt your performance to which I disagree.  But let's not make up false reasons like it makes waxing hard.  It takes me the same amount of time to wax my plane with and without.  And with the new ceramic wax stuff, it takes such a trivially short amount of time, and the result is so shiny fantastic, its not worth a blink of an excuse.

What a beautiful airplane!  What ceramic products do you use on it?