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Vortex generators on an Ovation?


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15 hours ago, cliffy said:

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.

Don Kaye wrote about a spin that he got into.

http://www.mooneyevents.com/spins.html

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I've done a hundred spins in a Cessna 150. Did them with my instructor before my PPE

I've done them in my old Cessna 140. In fact when I went for my Commercial ride in that 140, all the examiner wanted to do was spins. And he was the retired head of the old VNY GADO. 

But when the factory says "DON'T DO SPINS"  I  listen. There is a reason why they say it. 

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With a turbo Mooney...

Add Vgs then take data...

No need for before and after data...

Flying in the FLs will have the least effect on the air speed....

Landing speed will be nicely reduced...

 

If you insist on before and after data, consider using CloudAhoy to capture some additional data... :)

 

PP thoughts only, not a CFI...

Best regards,

-a-

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  • 2 months later...
On 6/11/2019 at 5:42 PM, 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.

IMG_2164.thumb.jpeg.6e364b8f5e5a9edb27bf1bcebe799f9a.jpeg

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.

After having them a year, is your opinion still the same? Any change in W&B. and any noticeable cruise speed loss?

On 6/11/2019 at 10:07 PM, ilovecornfields said:

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

Have they been installed yet?

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7 hours ago, carusoam said:

Too late to request before and after stall speeds?  :)

Best regards,

-a-

 

I didnt get a chance to stall before VG install in an Ultra, but did after. #3200 was 52-53 kts. Book says 59 kts at 3368 without, and I have no reason to doubt the factory tests. I only did the one stall, as time was against me my job was to get a couple of pilots up to speed in the plane, not acquire before and after data.

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15 hours ago, Niko182 said:

After having them a year, is your opinion still the same? Any change in W&B. and any noticeable cruise speed loss?

Have they been installed yet?

I just put them on in June and it's been a busy, hot summer so I haven't flown much so far, but I in a light wind situation I used to shoot for 70 kts. over the fence. I now feel I have just as much control at 65kts.

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50 minutes ago, Shadrach said:

This thread has been interesting. While I do appreciate the subjective post installation impressions (feels more “solid” at XXKTS), I’m really hoping for some actual same airplane before/after data.

Mine wasnt subjective. Before (by the factory test pilots) 59 VSO after (by me) 52 VSO. No comments on feel.

Its fairly worthless to ask for speed increase decrease over an F when this particular Ultra Acclaim had TKS also. Only your plane will know for sure, as they all have different evaluators as to how fast they cruise anyway :)

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1 hour ago, LANCECASPER said:

I just put them on in June and it's been a busy, hot summer so I haven't flown much so far, but I in a light wind situation I used to shoot for 70 kts. over the fence. I now feel I have just as much control at 65kts.

Do you have any pics of them installed on your Bravo?  I normally shoot for 75 kts short final, 70 ish over the fence.  Slower would be better...

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30 minutes ago, mike_elliott said:

Mine wasnt subjective. Before (by the factory test pilots) 59 VSO after (by me) 52 VSO. No comments on feel.

Its fairly worthless to ask for speed increase decrease over an F when this particular Ultra Acclaim had TKS also. Only your plane will know for sure, as they all have different evaluators as to how fast they cruise anyway :)

The VG-induced speed reduction for a TKS plane will probably be different from a clean wing, so I totally agree with Mike that it's plane specific, before/after.

 I run my TKS plane at 65* LOP mostly, and the fuel flows are lower than the book values for 29x2500 - I find the power settings tables pretty much useless with their 0/5 GPH up or down for 10* colder/warmer than standard temp.  13.5 x peak or modestly LOP fuel flow in GPH is what I recall the horsepower conversion factor to be from the APS people FF x conversion factor = HP; number for low-compression TSIO 550.) 

75% of 310HP /13.5 = 17.2 GPH.  That is what I'd target if I wanted to be super precise about it.  For flight planning purposes, I use the slider in Foreflight to retard the 29x2500 Best Economy cruise speed and fuel flow by 8% and 4% respectively, and that is usually right on. Standard day @ 16,000, 29x2500 = 17.4 and 214 KTAS in the book best power chart, So I'll call that "close enough" to 75%.

Anyway.... I, too, am really interested in a before / after or % less than book speed at a known power setting or fuel flow LOP.  On a TKS plane.  I'm on the cusp of getting VG's, but the potential for speed loss keeps me from pulling the trigger.  As with so much in aviation, the loss may be a good trade for the performance benefits - especially for someone like me who bases an Acclaim at a <2600' strip.  Is a further 4% speed reduction acceptable? 10%? 2%?  Dunno.  I'd plug those into Foreflight and see if I really care for my typical trips. But doing so would require me to make a decision rather than dwell on it more :-)

 

PS: Kevin Kammer told me at DMAX last year he does the stall speed tests in new production planes and for certification  at 3100# and 45".  I suspect the CG may influence Vso as well as cruise speed. I've recorded these for my plane and will report back if I do get VG's.

-dan

 

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I cannot speak to Mooneys, but I had a set of VGs on my PA-18 SuperCub. Compared to a non VG PA-18 the airplane was a monster. It would not stall power off. Slow flight you could zero the airspeed indicator (a lot of guys install helicopter airspeed indicators). I could go full flaps, level MCA and accelerate it a little bit to get it to stall. When it did stall, I could hold it in the stall and have full aileron control to the stops. Because of the aileron control, and the tail strake, the airplane could not be spun. I worked hard, and tried every trick in the book, power burst etc and it would never spin. On take off, I just got the tail up and pulled, it flew. On the top end it was no slower than a regular PA-18 but then again you are talking USA 35B airfoil with a top end of 85 knots. I can personally attest to slower stall speeds and better handling at low speeds because the energy over the ailerons is amazing. That is the reason why it "feels" solid in a Mooney is the energy over the ailerons.

Does it make the airplane slow on the top end? Answer is it depends, both on the wing and the VG. When the FAA made Bill Lear put them on the original Lear Jet it slowed the airplane 10 knots. Lear was so mad he went out to the prototype with a hammer and knocked them all off, then flew the airplane. The FAA was unimpressed and required them anyway. I would guess on a Mooney it might make a very slight difference on the top end, but not a lot. Drag rise is not that much compared to a jet. 

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Many years ago I put a set on a T-210.  I was operating from an uncontrolled field that had student traffic and was close to Class B airspace.  I really liked them since I had to follow a lot of 172 traffic and had little room to maneuver to stay behind them.  Stall speed was lower and controls were crisp right up to stall.  Down side  was I lost about 5kts in cruise.

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Perhaps those of you that have installed them can answer a couple of questions:

1. Did you find it necessary to recalibrate the stall warning by adjusting the position of the wing mounted vane?

2. Does it improve (soften) the touchdown of the nose wheel on landing?  

Skip

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On 3/9/2019 at 4:50 PM, steingar said:

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?

I’ve met you ,you are not at all like your description 

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On 8/17/2019 at 4:31 PM, GeeBee said:

Does it make the airplane slow on the top end? Answer is it depends, both on the wing and the VG. When the FAA made Bill Lear put them on the original Lear Jet it slowed the airplane 10 knots. Lear was so mad he went out to the prototype with a hammer and knocked them all off, then flew the airplane. The FAA was unimpressed and required them anyway. I would guess on a Mooney it might make a very slight difference on the top end, but not a lot. Drag rise is not that much compared to a jet. 

That is really funny.  :-)

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ol' man Lear actually called those VGs  "f*#k up fixers"  He was embarrassed by them 

I agree with him...you are converting a laminar flow wing to a non laminar flow. Like buying a corvette and putting truck tires on it for better off road performance.
Of course I don’t like the stall strips for the same reason.


Tom
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4 hours ago, thinwing said:

Had them on a lake amphibian....Was out on the water with the gf wearing a bikini.She was not amused when the damned things tore her bottoms while lounging on the wing

But you probably had to help her change clothes, so I guess there really are some pros and cons... B)

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Very hard to design a true laminar flow airfoil that stays attached for 100% of the cord at high angles of attack. 

Don't think it can be done.

The F^*K UP fixers of course kept flow on the ailerons.  They were well aft on the cord line so most of the flow was laminar unlike the VGs on the leading edge of the wing on  laminar flow Mooney airfoil !!!!!.

I talked with them a few years ago and they seemed convinced that the VGS on a Mooney didn't affect the cruise speed. 

Haven't found a real before and after test yet. 

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I have some data and before and after cruise on our Acclaim. I record for every flight.Based on a5 before and after flights comparison before and after 29" 2400 LOP FL140. near max takeoff weight, (ranging between -8 degrees C and -14 degrees C). Before average TAS 192, after average TAS 189.5

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