Vortex generators on an Ovation?

[carusoam]

The key things to look for...

1) there is no doubt the Vgs work at lowering stall speed...

2) We have examples of the Acclaim where these work as advertised...

3) The Acclaim unfortunately didn’t give us a hint on speed reduction penalties at 12.5k’... where my O spends plenty of time...

4) expect some speed reduction that wants to be known...

5) The reason we use the words proper pilot technique.... this is what the PIC does... because they are responsible for the general safety of the flight....

 

PP thoughts only, not a CFI, or mechanic...

Best regards,

 

-a-

[Shadrach]

8 hours ago, M20F said:

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. 

There is no reason why a Mooney would "kill most pilots" more than any other clean XC machine.  To be clear, I have never had my plane in what would be classified as a spin   I have done full power stalls that led to an incipient spin (left wing dropped >90°)  and the airframe responded to the same anti spin inputs that as any other airplane would. I lost almost 500ft in the process. I would not recommend intentionally spinning a Mooney because 1) it's illegal and 2) the airframe will build speed faster than most aircraft.  It does however respond to normal anti spin controls.  If one were inclined to break the regs, I am certain one could spin their Mooney repeatedly and recover repeatedly over and over. That being said, I think it's bad idea and the wrong tool for the job.

Edited March 10, 2019 by Shadrach

[Shadrach]

4 hours ago, MIm20c said:

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. 

If  the VGs are doing their job, the stall should occur at a higher AOA. Many VG wing installations have corresponding installations on the underside of the horizontal stab.

Edited March 9, 2019 by Shadrach

[M20F]

7 minutes ago, Shadrach said:

I have done full power stalls that led to an incipient spin (left wing dropped >90°)  and the airframe responded to the same anti spin inputs that as any airplane other would. I lost almost 500ft in the recovery.

I wasn’t sitting next to you but a wing dropping in a stall isn’t a spin.  A little aileron, bad rigging, etc.  All it means is one wing exceeded critical AOA first.  

Mooneys are hard to get into a spin, it is hard to hold it in a spin (progresses quickly to a spiral), and they are slow to recover from a spin.  It isn’t a Cessna.   

[aviatoreb]

31 minutes ago, Shadrach said:

If  the VGs are doing their job, the stall should occur at a higher AOA. Many VG wing installations have corresponding installations on the underside of the horizontal stab.

The Mooney VG STC includes VGs on the underside of the horizontal stabilizer - so that's what is on my airplane.

I agree re the AOA - as the stall speed is now at a slower speed this corresponds to a higher angle of attack at stall.  So a lower tail.  I doubt it would be anything near a tail strike.

[Shadrach]

8 hours ago, steingar said:

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.

Your 1500 number is at MGTOW.  Land lighter, land slower...  I have never seen a public field with a 50' obstacle that did not have a displaced threshold in place to account for the obstacle. My favorite little strip is 1840' of pavement but due to the trees, the FAA keeps moving the threshold.  The up hill runway has 1510' available for landing.  There has been a C model based there for years.  The margins are certainly tighter then a big long runway, but it's still quite a ways from the ragged edge of what's safe... I've landed there maybe 50 times.  The key is judging the approach and going around before it goes from not great to pear shaped.  My experience tells me that pilots don't need a short strip to prang a Mooney (or anything else) when landing. Someone deposited an F model off the departure end of our 5900' runway after two attempts  to land.  I challenge myself when solo because I believe it makes me a more comfortable and capable pilot.  I frequently fly with passengers. I increase my margins considerably with non-pilot people on board.  This means there's a large delta between what I can do and what I will do when I have pax on board. That's part of my approach to being a good steward with the lives of others.

Edited March 10, 2019 by Shadrach

[PT20J]

Seems like everyone wants improved low-speed performance with no effect on the high speed end. Isn't that "something for nothing"? Doesn't that defy nature? Besides, I thought all you "Big Bore" guys were putting around severely LOP at Carson speed boasting about low fuel flows because the big engines guzzle fuel and the stuff has gotten so darned expensive. OK, I'm kidding. Here's a reasonable analysis based on a similar airplane:

Vgs_cruise_wide_screen.pdf

Skip

[Shadrach]

2 hours ago, M20F said:

I wasn’t sitting next to you but a wing dropping in a stall isn’t a spin.  A little aileron, bad rigging, etc.  All it means is one wing exceeded critical AOA first.  

Mooneys are hard to get into a spin, it is hard to hold it in a spin (progresses quickly to a spiral), and they are slow to recover from a spin.  It isn’t a Cessna.   

RTFP!

1) I never said it was a Cessna. I said it responded to anti spin inputs like any other certified aircraft. It does.

2) I did not say a spin, which is a stable condition. I said incipient spin. One wing reaching critical AOA first is kind of an important part of that process.

3) This was not just a wing drop (My plane stalls pretty level power off) this was an abrupt drop to the left past inverted with a recovery on a heading about 290 from where we started

Edited March 10, 2019 by Shadrach

[PT20J]

On 3/8/2019 at 3:55 PM, ArtVandelay said:

Maybe true for slow non laminar flow wings

Not sure I understand that. Cherokees have a laminar flow wing and they are kind of slow...

Actually, it's almost impossible to make a laminar flow wing as North American found out when they built the P-51 (generally acknowledged to be the first aircraft designed to purposely use a laminar flow airfoil). The wing has to be built to uneconomical manufacturing tolerances and polished smooth in order to not trip the boundary layer. It's not the wing that makes the Mooney have low drag -- it's the small wetted area and general aerodynamic cleanliness of the design.

Skip

[PT20J]

7 hours ago, M20F said:

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

Takes a lot of g's to stall at maneuvering speed - maybe that's your spin problem.

The modern Mooneys will have met the normal category spin requirement of recovering from a one turn spin in one additional turn. Beyond that you're the test pilot. BTW, a spin isn't fully developed (i.e., the yaw and pitch rates have stabilized) until somewhere between one and two turns -- until then it's still classified as incipient. 

Skip

Edited March 10, 2019 by PT20J
typo

[steingar]

4 hours ago, kortopates said:

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

Without an obstacle the numbers are different, and 1500 becomes doable. But hereabouts no field that short is going to be without trees at one end at least, and I’ve seen more than one that function as one way strips.  Like I said, I’m not going in on the edge of the envelope.  What have I to gain? I don’t know of a single such strip that doesn’t have a much longer strip within a ten minute drive with one exception. The exception is on an island.  What a great idea, prang your Mooney on an island!

if someone was going to die if I didn’t get them out of there I’d chance my skill against that.  Other than that, forget it. 

Like I said, do what you like. But I know what my book says, and I very rarely have better conditions.  The guys who wrote that book had a shiny new airplane and an experienced test pilot who probably had chisled good looks and a girl at every airport. I have a 56 year old airplane with an inexperienced pilot who’s fat, bald, old, ugly and who has but one old lady who right now has the flu.  I hope you’ll forgive me for not wanting to be a test pilot with one of my major investments. What have I to gain?

[PT20J]

1 hour ago, steingar said:

I have a 56 year old airplane with an inexperienced pilot who’s fat, bald, old, ugly and who has but one old lady who right now has the flu.  I hope you’ll forgive me for not wanting to be a test pilot with one of my major investments. What have I to gain?

Sorry about the flu - that sucks!

Since you asked, here's what I think you have to gain. I used to give a lot of flight reviews, and I noticed that the recently minted pilots were pretty comfortable with slow flight, stalls, steep turns, short field landings, etc. And why not? They passed a checkride in the last couple of years where they had to demonstrate proficiency in all that stuff. I also noticed that many more experienced pilots - and especially airplane owners - had grown uncomfortable getting anywhere near the edge of the envelope. Hell, some didn't even like to fly without the autopilot. Proficiency wanes over time with disuse. You may never need to land on a 1500 foot strip. But, you will be a more confident pilot for knowing you could if you had to. There is no need for steep turns in normal flying, but you'll have much better command of the airplane if you can do them within ACS standards. Same with all the standard maneuvers and especially crosswind takeoffs and landings. It's fun to practice, gives a great sense of accomplishment when you can do the maneuvers well, and it's another excuse to fly. And then one day when the engine become disinterested in further toil, and the only place to go is a 1500' strip, you'll be ready.

Skip

[steingar]

I live in Northeastern flatistan. Should my engine ever take a dump I’m not in any way worried about finding someplace smooth to land,

i agree with one thing. Trying to hone one’s landing skillls so that you can routinely and comfortably put your crate down in the first 1500 feet of the runway is a very good thing that every pilot should do.  Going into and out of said 1500 feet is madness if your book says you need 1500 feet to land. Like I said, what have I to gain?  Where I live there are almost always longer runways nearby. So why does one have to fly on the edge of the envelope sans emergency? Why take that kind of risk if you don’t have to?

I have no doubt whatsoever that someone will reply to this boasting of their prowess and how they’ve landed 1500 foot stops routinely for years. I can only counter that the accident databases are full of folks for whom it didn’t work out so well.

[Gary0747]

Two things to never do in a Mooney, especiall a 50 yr old one.

1. Accelerated stalls

2. Spins

some of the original Mooney test pilots had stories about the tendancy to get the vintage stuff into flat or semi flat spins and their harrowing experiences of recovery. The tendancy for flat spins in increased the more aft the CG. 

[Austintatious]

man, after seeing the price of a bunch of pieces of plastic, I have come to realize that I am in the wrong business!

 

I have a 3d printer... maybe I will get it humming!

Edited March 13, 2019 by Austintatious

[LANCECASPER]

43 minutes ago, Austintatious said:

man, after seeing the price of a bunch of pieces of plastic, I have come to realize that I am in the wrong business!

 

I have a 3d printer... maybe I will get it humming!

The VGs aren't plastic and there are 180 of them on a Mooney.

https://microaero.com/ocs/?socs=mooney-ocs.pdf

[Austintatious]

aluminum?

I assumed they were because  a GV has vortex generators on the bottom of the horizontal, they are v shaped, and they are made of plastic... G5 goes .885 and to 510~!

[Shadrach]

44 minutes ago, Austintatious said:

man, after seeing the price of a bunch of pieces of plastic, I have come to realize that I am in the wrong business!

 

I have a 3d printer... maybe I will get it humming!

You’re mistaken. The real cost is in the paper.

[Austintatious]

Just now, Shadrach said:

You’re mistaken. The real cost is in the paper.

you got that right!

(my comment was tongue in cheek... you guys are a tough crowd!)

[LANCECASPER]

I ordered a kit at Sun N Fun in April and just installed them during this annual, completed last week. I live at an airpark that has high density altitude in the summer, so any extra margin is welcome.

I have only two short flights with them so far, so no comment on loss of cruise speed.

However with light winds I usually shoot for 75 knots on final, 70 over the fence. I came over the fence at 65 both times this weekend and made the 1st turnoff. At 65 knots with the VGs it felt lot more solid than it did at 70 before the VGs.

[aviatoreb]

6 minutes ago, LANCECASPER said:

I ordered a kit at Sun N Fun in April and just installed them during this annual, completed last week. I live at an airpark that has high density altitude in the summer, so any extra margin is welcome.

I have only two short flights with them so far, so no comment on loss of cruise speed.

However with light winds I usually shoot for 75 knots on final, 70 over the fence. I came over the fence at 65 both times this weekend and made the 1st turnoff. At 65 knots with the VGs it felt lot more solid than it did at 70 before the VGs.

Great!

but careful / it does stall much slower but also the sensation right before it stalls is different since now you will have more crisp control feel much closer to the onset of stall.

[exM20K]

@LANCECASPER the factory does th stall series at 45” and 3100#. I’d be very interested in a book vs VG Vso comparison. Also cruise speed loss.  I’m in the same boat with a short field and have been agonizing over this for months. 

 

Thanks in advance.

-dan

[LANCECASPER]

I'll check it out on my next trip and report back. I'll be surprised if there's more than a knot or two loss in cruise. 

I talked to them to them at the booth at Sun N Fun and they used a Bravo to obtain their approval for Mooneys. Their data showed 8% reduction in stall speed and no reduction in cruise. I'm willing to lose a couple knots in cruise for the reduction in stall speed.

I did all of the painting of the VGs and then I did the installation during my annual. My IA inspected my work and signed it off.

They say it can be done in a day. With everything I probably had 12 hours into it since it was the first time I've ever done one. The kit is very complete with tools, etc and the instructions are excellent.

[cliffy]

Mooney spins?

Had a one on one talk with Bill Wheat several years ago and he said he got into a 5 turn spin and almost didn't get out of it.

Said he'd never go that far again. 

I've heard folks talk of spinning their Mooney and I walk away shaking my head.

I guess I've done this flying stuff for too many years.

[ilovecornfields]

4 hours ago, LANCECASPER said:

I ordered a kit at Sun N Fun in April and just installed them during this annual, completed last week. I live at an airpark that has high density altitude in the summer, so any extra margin is welcome.

I have only two short flights with them so far, so no comment on loss of cruise speed.

However with light winds I usually shoot for 75 knots on final, 70 over the fence. I came over the fence at 65 both times this weekend and made the 1st turnoff. At 65 knots with the VGs it felt lot more solid than it did at 70 before the VGs.

Nice! I’m getting mine installed in August during the annual.