Re: COZY: Approaching Deep Stall


Izzy
 

My son and I share ownership on an Aeronca Chief my Dad restored. He installed VG’s at one point and I learned a few things about them as a result.

Without VG’s the stall of the Aeronca wing is somewhat predictable and manageable. I can slow down to about 39-40 mph and continue to hold altitude, if the airspeed indicator is to be believed, before the plane starts to stall. The onset is a mush and a slow roll one one way or the other. 

With the VG’s installed, the plane can slow down to as low as 32 miles per hour. When the stall happens, it is violent, sudden and requires more time, power and altitude to recover before entering into a spin.

The thing I learned is, although VG’s can help you slow the speed at which the wing will stall, it doesn’t magically add more energy to the system. And as a result, when a stall does happen, much more energy needs to be added before return to controlled flight happens. Maybe it comes from trading altitude for airspeed (hard to do when just over the runway trying to land), or by adding lots of throttle (which takes a moment or two before it’s effect yields an increase in control). 

The reason my Dad installed them was to help the Aeronca get up on to the “Water Step” for a floats equipped takeoff, allowing for departure from smaller lakes and rivers. But the poor controllability at 32 miles per hour basically makes the plane a wheels-only landing Aeronca when there is any kind of gusting conditions when using the standard landing gear. 

Not sure if that anecdote helps at all, but felt it worthy of mentioning. I’d be curious if anyone who actually knows something about aerodynamics could comment. Maybe I just suck at landing Aeroncas :0

Izzy
(603)410-7277

On Aug 25, 2022, at 13:04, skybob8 <quickstrip@...> wrote:

If “VG,s” were to be placed on main wing and canard per supplied temples and instruction, do you feel that the stall characteristics (the bob) would be changed or should they be the same except at slower speeds.

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