ilovecornfields

Vortex generators on an Ovation?

Recommended Posts

*Members that donate $10 or more do not see advertisements*

@mike_elliott had some experience with them on a new Acclaim Ultra that he delivered.

Lowering the stall speed by 8% is intriguing with supposedly no effect on cruise speed.

 

If anyone wants them they can use my Aircraft Spruce discount. They only offer 5% off on these, but $72.50 savings helps.

813552143_ScreenShot2019-03-07at7_06_13PM.thumb.png.0d2d5b78a3ad7f816f8d8675de79a25e.png

Share this post


Link to post
Share on other sites

I have them.  I really like them. The airplane has a slower stall speed and the airplane maneuvering is still rather more crisp than mushy as it gets slow, so overall much better slow speed handling.  I figure they are a safety item because slower stall speed means you land shorter runways, and also if you ever need to make an off field landing, then that's less Kinetic energy upon touch down.

For cruise speed - am I slower?  Intuition suggests I would be slower.  They claim no loss in cruise speed.  The argument is plausible, that they sit low and back below the boundary layer that is thicker at cruise speed but the boundary layer is thinner at slow speeds so they do stick into the flow at slow speed vs cruise speed.  

But I am slower in cruise - I don't blame the VGs - I blame the tks.  Which is upstream the Vgs.  My guess is that it is plausible the vg's don't hurt my cruise any more than already hurt by Tks but in any case, once the flow is disturbed due to tks, then no further harm as the flow is already disturbed.  Just guessing.

Anyway - great slow speed handling is unmistakable.  Slower stall - crisper slow speed handling.

Edited by aviatoreb
  • Like 2

Share this post


Link to post
Share on other sites

I looked into VGs some time ago.  Unfortunately, there is no gross weight increase , no airspeed benefit, and a loss of a bit of useful load, so you're essentially paying $1450 + installation to lower your stall speed by a few knots, as @LANCECASPER Lance indicated.  No real tangible benefit or justification for spending the money, IMHO.

Share this post


Link to post
Share on other sites

Lowering the stall speed by 8% is intriguing with supposedly no effect on cruise speed.

I have a problem with that claim. If you are disturbing the air, effectively making the wing non laminar flow, creating vortexes....but no extra drag?! You cannot defy the laws of physics. We add winglets to get rid of vortices, we use a laminar flow wing for less drag...now someone claims that’s all wrong? Seriously? It may not significantly decrease cruise speed, but no effect, I don’t think so.


Tom

Share this post


Link to post
Share on other sites
17 minutes ago, ArtVandelay said:


I have a problem with that claim. If you are disturbing the air, effectively making the wing non laminar flow, creating vortexes....but no extra drag?! You cannot defy the laws of physics. We add winglets to get rid of vortices, we use a laminar flow wing for less drag...now someone claims that’s all wrong? Seriously? It may not significantly decrease cruise speed, but no effect, I don’t think so.


Tom

I find it entirely plausible based on the varying thickness of the boundary layer as speed increases argument and cleverly designing the fins depth and placement accordingly.  Physics of fluids is very very nontrivial, I promise.  What actually happens between this asserted theory and practice I have not been to the wind tunnel or done the engineering tests. As a theorist I say I see absolutely no contradiction in physics.

  • Like 1

Share this post


Link to post
Share on other sites

I put VGs on a 78 T210 i owned years ago.  I liked them in the low speed regime but they did cost 5Kts in cruise.  I think on a Mooney it would give a very pleasant low speed performance but you would lose cruise.  You might also find you lose value on your aircraft because most buyers salivate about the speed and are willing to live with resulting takeoff and landing performance.  

Share this post


Link to post
Share on other sites
I have not been to the wind tunnel or done the engineering tests.

Neither has manufacturer I’m sure, just because they have a PMA doesn’t mean the marketing hype is true.


Tom

Share this post


Link to post
Share on other sites
1 hour ago, ArtVandelay said:


Neither has manufacturer I’m sure, just because they have a PMA doesn’t mean the marketing hype is true.


Tom

It seems like the comments from the very few people here who actually have them is that they  do what they’re advertised to do. . Not sure how you would lose value since you are able to remove them. I asked my mechanic about it and I think he’s correct that people don’t install them because they’re more obsessed about making Mooneys fly faster than fly slower. I see a real benefit in flying slower.

I think I’ll get them installed either this annual or next. I’ll post a PIREP and let you all know how I wasted my money and ruined my airplane. ;-)

  • Like 1

Share this post


Link to post
Share on other sites
17 minutes ago, ilovecornfields said:

It seems like the comments from the very few people here who actually have them is that they  do what they’re advertised to do. . Not sure how you would lose value since you are able to remove them. I asked my mechanic about it and I think he’s correct that people don’t install them because they’re more obsessed about making Mooneys fly faster than fly slower. I see a real benefit in flying slower.

I think I’ll get them installed either this annual or next. I’ll post a PIREP and let you all know how I wasted my money and ruined my airplane. ;-)

I also a lot of people who KNOW what they will do but have no direct information. I find they do exactly as advertised.

BTW indeed they are trivial to remove.  Absolutely trivial.  I don't plan to.

The only down side is it is a tad harder to wax and wash the plane.

 

Share this post


Link to post
Share on other sites
It seems like the comments from the very few people here who actually have them is that they  do what they’re advertised to do. . Not sure how you would lose value since you are able to remove them. I asked my mechanic about it and I think he’s correct that people don’t install them because they’re more obsessed about making Mooneys fly faster than fly slower. I see a real benefit in flying slower.
I think I’ll get them installed either this annual or next. I’ll post a PIREP and let you all know how I wasted my money and ruined my airplane. ;-)

The improved slow flight I don’t have a problem with..it’s “no effect on the cruise speed” statement. Maybe true for slow non laminar flow wings, but not Mooneys IMHO. If you do get them, be sure you get accurate before and after speed runs.


Tom

Share this post


Link to post
Share on other sites
52 minutes ago, ArtVandelay said:


The improved slow flight I don’t have a problem with..it’s “no effect on the cruise speed” statement. Maybe true for slow non laminar flow wings, but not Mooneys IMHO. If you do get them, be sure you get accurate before and after speed runs.


Tom

Seems like the posts from the guys that have them indicate they work as advertised. I'll take that over a theoretical argument any day of the week. 

  • Like 1

Share this post


Link to post
Share on other sites

Had vortex generators on my Cherokee. Sucker was fast for a Cherokee.  Couldn’t stall the damn thing anyway I tried. Landed a good 10 knots slower than book.  If landing short strips is your thing the generators are must have.  They’ll save you all that money from prop strikes, overruns, and whatever else.  If all you do is land long asphalt runways, don’t bother.  But if you need to come in short routinely for whatever reason, you want. The investment is well worth it.  You will control you aircraft crisply all the way into the mush you’ll get in place of the stall.

Don’t have a plan to put them on mine only because I fly out of one long big city airport and land another. My Mooney is a travel machine, and I don’t travel to the sticks.  But if you do, get them.  You won’t be sorry.

  • Like 1

Share this post


Link to post
Share on other sites
11 hours ago, ilovecornfields said:

It seems like the comments from the very few people here who actually have them is that they  do what they’re advertised to do. . Not sure how you would lose value since you are able to remove them. I asked my mechanic about it and I think he’s correct that people don’t install them because they’re more obsessed about making Mooneys fly faster than fly slower. I see a real benefit in flying slower.

I think I’ll get them installed either this annual or next. I’ll post a PIREP and let you all know how I wasted my money and ruined my airplane. ;-)

 

Collecting and posting before and after data will generate a thread that will get a very high level of interest.

Use all proper piloting techniques and Go for it!

Best regards,

-a-

Share this post


Link to post
Share on other sites
43 minutes ago, carusoam said:

 

Collecting and posting before and after data will generate a thread that will get a very high level of interest.

Use all proper piloting techniques and Go for it!

Best regards,

-a-

I’ve never used proper piloting technique before. Why should I start now?!

  • Like 2
  • Haha 1

Share this post


Link to post
Share on other sites
On 3/7/2019 at 8:37 PM, LANCECASPER said:

No Mooney testimonials but interesting reading. . . .  https://microaero.com/testimonials/

I like data. Testimonials are often a bit tainted by the need to justify the install. My airframe has pretty benign stall characteristics unless I’m doing full power, departure stalls in which case it rolls left opposite the prop as you’d expect. My flight review was earlier this month, during which I made several circles at 57MIAS, stall horn blaring, with two 200lbs pilots in the front seats. It started to buffet at ~55MIAS and broke just above 50MIAS.  Who is flying this airframe and feeling like it’s hampered by poor slow flight/stall characteristics? 

Share this post


Link to post
Share on other sites
3 hours ago, Shadrach said:

I like data. Testimonials are often a bit tainted by the need to justify the install. My airframe has pretty benign stall characteristics unless I’m doing full power, departure stalls in which case it rolls left opposite the prop as you’d expect. My flight review was earlier this month, during which I made several circles at 57MIAS, stall horn blaring, with two 200lbs pilots in the front seats. It started to buffet at ~55MIAS and broke just above 50MIAS.  Who is flying this airframe and feeling like it’s hampered by poor slow flight/stall characteristics? 

And ... one could say that your statements about what VGs can and can't do, never having flown in such an airplane, may be a bit tainted to justify your decision not to get them.  Who is saying?  I will say if my airplane stalls at 15 knots and you show me a way to lower the stall speed to 11 knots I will sit up straight and ask how - my opinion: there is no thing as too slow when it comes to stall speed.

There is nothing wrong with the stall characteristics of a Mooney.  they are fine and benign airplanes.  Nonetheless it is a fact that the stall speed is lowered, several knots.  And the stall characteristics as good as they are without, are even better.  Some, few, of us value the possibility of touching down even slower.  For safety in case of an incident.  And for shorter field performance.  I think Mike Elliot testified that he flew an ultra with them and they did not diminish cruise speed but anyway one simply cannot assert without experience anything about what they do to cruise speed or the fact that they lower stall speed.

Edited by aviatoreb

Share this post


Link to post
Share on other sites
4 minutes ago, aviatoreb said:

And ... one could say that your statements about what VGs can and can't do, never having flown in such an airplane, may be a bit tainted to justify your decision not to get them.  Who is saying?  I will say if my airplane stalls at 15 knots and you show me a way to lower the stall speed to 11 knots I will sit up straight and ask how - there is no thing as too slow.

There is nothing wrong with the stall characteristics of a Mooney.  they are fine and benign airplanes.  Nonetheless it is a fact that the stall speed is lowered, several knots.  And the stall characteristics as good as they are without, are even better.  Some, few, of us value the possibility of touching down even slower.  For safety in case of an incident.  And for shorter field performance.  I think Mike Elliot testified that he flew an ultra with them and they did not diminish cruise speed but anyway one simply cannot assert without experience anything about what they do to cruise speed or the fact that they lower stall speed.

I have flown several PA 28s with and without VGs and can confirm that  VGs do indeed work.  They were useful for demonstrating that VGs lower stall speed and little else with regard to normal operations.  I am comfortable going in and out of 1600' strips as it is which is way more than I need.    If I was building a STOL aircraft for the back country, then I would put VGs on it. It's not something I'd do to my Mooney as I spend little time during normal ops at the ragged edge of a stall. Big wing spoilers provide down force even when on street driven passenger cars but they're not really useful for the kind of driving that most street legal passenger cars engage in. I would therefore not add one to my car. To each there own. The other side of it is that your plane is so tricked out there's no low hanging fruit left.  There are so many place that I could put money into my time capsule that VGs don't warrant a thought.

Share this post


Link to post
Share on other sites
5 minutes ago, Shadrach said:

I have flown several PA 28s with and without VGs and can confirm that  VGs do indeed work.  They were useful for demonstrating that VGs lower stall speed and little else with regard to normal operations.  I am comfortable going in and out of 1600' strips as it is which is way more than I need.    If I was building a STOL aircraft for the back country, then I would put VGs on it. It's not something I'd do to my Mooney as I spend little time during normal ops at the ragged edge of a stall. Big wing spoilers provide down force even when on street driven passenger cars but they're not really useful for the kind of driving that most street legal passenger cars engage in. I would therefore not add one to my car. To each there own. The other side of it is that your plane is so tricked out there's no low hanging fruit left.  There are so many place that I could put money into my time capsule that VGs don't warrant a thought.

So we are agreed.  To each their own.

I value lowering stall speed as a matter of safety "just in case" and in that regard I believe for my own sake there is no such thing as too slow to bother thinking about even slower.

As to our different airframes, mine is heavier, I won't go into a 1600' strip with or without my VGs.  2000ft is my absolute personal mins, and 2500 if I am unfamiliar.  Even though yes I can get it stopped well sooner.  

  • Like 1

Share this post


Link to post
Share on other sites

Just curious, the tail sits pretty low on the long bodies. Do the VGs change the angle of attack during the stall?

i would think 310 hp and VGs would really transform runway requirements. 

Share this post


Link to post
Share on other sites

I’m not going into any 1600 foot strips anytime soon. Last I checked my crate needed 1500 to land over a 50 ft obstacle, and most of the trees around here plum forgot to stop growing at 50 ft. Do what you want, but I want a much bigger margin of safety. A superior pilot uses his superior judgement so he doesn’t have to use his superior skills. I’m not a superior pilot, but I’d like to live to be one some day.

  • Like 1

Share this post


Link to post
Share on other sites
2 hours ago, aviatoreb said:

There is nothing wrong with the stall characteristics of a Mooney.  they are fine and benign airplanes. 

The are fine stalling planes as a maneuver with the ball centered and at Va.  Inadvertently it is a different story and it’s spin characteristic’s will scare the hell out of you and kill most pilots (I really don’t encourage anyone spinning one without somebody who really truly knows what they are doing).  

It isn’t a Piper Warrior, don’t let a maneuver confuse you with what happens when you don’t expect it to happen.  We tend as pilots to practice maneuver’s and equate that to what is going to happen which isn’t usually the case. 

  • Like 1

Share this post


Link to post
Share on other sites
I’m not going into any 1600 foot strips anytime soon. Last I checked my crate needed 1500 to land over a 50 ft obstacle, and most of the trees around here plum forgot to stop growing at 50 ft. Do what you want, but I want a much bigger margin of safety. A superior pilot uses his superior judgement so he doesn’t have to use his superior skills. I’m not a superior pilot, but I’d like to live to be one some day.

Although your point is well taken, no one here is speaking of dropping a Mooney into a short strip over a big obstacle. I think the point is it's very doable with very good short field technique that includes precise speed control. After all the private pilot ACS standards are much more precise than being 50' high at the numbers and commercial requires within 200' without the engine - with an unobstructed runway of course.

But it takes time in type and lots of practice to get there and while working on it good saftey margins are essential. So I certainly don't mean to sound critical of you. Quite the contrary, You're being real smart to know your numbers and add a good margin which will serve you well.


Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.