VG's

Cruzinchris

Cruzinchris

Pre-takeoff checklist
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Cruzinchris
I think the conscious would be that Vortex Generators are a good thing since they enhance safety by reducing stall speed. They are especially effective on my Beechcraft Sport. Vs goes from 63k to 53k.

My question: Would the speed that the Stall Warning Horn goes off stay the same? Seems like it would, because the AOA would be the same??
 
The VGs reduced you stall?

Always thought VG more increased low speed controllability vs actually lowering the stall.
 
They do both. My Cherokee had its stall speed reduced at least 10 mph. But more importantly (to me) it was completely controllable all the way into the stall, and was real work to stall. Most days the best I could do was get it into a mush, I either ran out of elevator authority or muscle. If your'e going into lots of short strips or working on the slow end of things they are a very, very good investment.
 
Yeah, the stall horn was designed on your aircraft to indicate an impending stall based on your original config. Now you’ve got VGs which will allow a higher AOA without the wing stalling. Stall horn will still go off at the original AOA.
 
The stall horn will likely go off intermittently. The VG planes I've flown will give you 1-2 seconds of stall horn on up drafts in slow flight. They are not a panacea. On Cessna's for example, VG's on 182's and 172's provide some additional control in slow flight, with low side effects in cruise for the 172, but tend to reduce cruise performance on 182's. In both cases your sink rate is accelerating as flight slows to the edge of stall. Be very careful at the edge of stall as you can be deluded into thinking the stall margin is broader than it really is, and can get a pilot into trouble.

VG's seems to work better on some planes over others. Really depends on the outcome you are looking to achieve.
 
NordicDave said:
...VG's seems to work better on some planes over others...
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Appears to depend a lot on the wing. Seem to be more effective on thin or laminar flow wings, less of an improvement on fat, high lift wings like the Supercub or my Aztec.
 
VGs on my Cessna wing allow slower airspeed for the same attitude when flying slow, like on approach. If the approach is at 65mph before, you get the same deck angle at 60mph after.There is no impact on the stall horn relative to stall attitude. AOA is AOA. The same is true for Cubs but for me it wasn't as pronounced as with the Cessna. Aileron control at slow speeds is improved in the Cessna but at slow speeds the Cub is already a rudder airplane so VGs didn't make much impact there. The under stab VGs improve the elevator effectiveness at slow speeds with both types.
 
Agree with what Stewart said above.

One other thought concerning VG's... in the 172 I recently flew with VG's.... you need to be RIGHT on speed when landing. Any excess speed caused this plane to float excessively in ground effect. It's less mussy and more precise at the edge of slow flight. My first 2 short field landings were 5 mph too fast and had to go around to make sure the approach was stabilized at exactly 70-75 crossing over the fence before chopping the small bit of remaining power. Landed at about 65-70 mph.

By no means am I condemning VG's, hopefully providing some useful experience.
 
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steingar said:
They do both. My Cherokee had its stall speed reduced at least 10 mph. But more importantly (to me) it was completely controllable all the way into the stall, and was real work to stall. Most days the best I could do was get it into a mush, I either ran out of elevator authority or muscle. If your'e going into lots of short strips or working on the slow end of things they are a very, very good investment.
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is this the Hershey bar wing or the semi-tapered?
 
I am a firm believer in VGs.

I installed them when I owned the Commander - dramatic difference in low-speed controllability and reduction in stall speed - to the point that I would get a very high deck angle when attempting a power-on stall (which enough that we'd generally recover based on deck-angle rather than amount of power). Stall horn was at or close to normal AOA for a stall. In slow flight/impending stall with flight following, I'd regularly get queried by ATC (for near zero ground speed) when doing them into the wind.
 
steingar said:
Hershey bar. As you can tell Was quite impressed. That said I'm not in a big hurry to put them on my Mooney. Landing short strips isn't exactly its speciality.
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i have been thinking about VG's on the semi-tapered archer wing for a while now... havent pulled the trigger yet. it mushes down in a stall anyway.. not sure if the VG will be actually worth it
 
I just bought a set of VGs for the Sierra, but I haven't installed them yet; I'm curious to see the difference.
 
I my buddies Duke, the VGs winglets and tail cone thing make the plane fly significantly better.
When the plane was advertised some of the marketed abilities were deadly if an engine went out. With those three things added an engine out is just an expensive inconvenience.
Haven’t thought about putting VGs on on my Archer. There is some controllability to be desired at low speeds but I wouldn’t call it a nuisance or necessary to fix.
 
VGs on a Husky slow it down 3 or 4 knots. They do make it stall a little slower and give it more elevator authority so you can get the tail down for landing at very slow speeds. They really aren't needed IMO.
 
No doubt VGs can be very helpful for certain aircraft or operations such as very short fields or low speed controllability and stall resistance in some unusual situations like emergency turns in a box canyon, or even resistance in the stall/spin accidents in the pattern when inattentive to airspeed. However, for the semi-tapered Archer in low elevation areas, I haven't experienced the need. In fact, while it is normally a desirable attribute for your aircraft to land at the lowest speed possible at full stall, I find it desirable to have the wing stall at normal or higher stall speeds in Archers that don't have VGs to increase tail effectiveness in strong crosswind and/or gusty crosswind conditions. I often increase my final speed and land at/near the resultant higher stall speed with reduced or no flaps as needed in those conditions to increase controllability and to avoid running out of rudder. I suppose if one had VGs, one could customize the flaps as well to increase the stall speed in those conditions. Keeping the wing flying is not always desirable.
 
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MajorTurbulence said:
I suppose if one had VGs, one could customize the flaps as well to increase the stall speed in those conditions. Keeping the wing flying is not always desirable.
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This was my experience flying a 172M all last week with VG's. In ground effect, it would not stop flying if the airspeed was not right on speed. My 182 has an active Robertson STOL kit that converts the ailerons to flaperions, with stall fences on the wing keep the stall from traveling past the flaps and onto the aileron.

If I had a 172 and needed to land on short grass fields, I'd get VG's otherwise not really sure they are worth the cost and effort.
 
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On the Cub, VG's made a huge difference, surprised to hear that Stewartb didn't get the same improvement we did! On spray planes, it is night and day. Only reason haven't put them on the wagon, is I don't wanna clean around them, polished aluminum.


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I was less in tune with my Cub than with my Skywagon.

My first landing with VGs, to a short and narrow strip that I’ve used with my Wagon for over 20 years, was 10% shorter using exactly the same technique I always used. The deck angle was the same but airspeed was slower. Guys talk about all kinds of stall speed stuff and aileron stuff but for me the big change was that the AOA remained equal at slower speed. No hanging on the prop or high AOA attitudes required. Fly the plane with your customary deck angles and control feel and your speed is slower. On the flip side, going out over big obstacles in unfavorable winds? Thrust is thrust and that didn’t change for me, but the safety margin for controlling the plane improved. Hard not to like that.
 
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