[NSRCA-discussion] How I became an expert Snap Judge (TIC)

[James Oddino]

Ron, I agree completely with you and Jerry.  My point is we can get a  
similar airframe response at similar asymmetrical lift on the left  
side by using ailerons along with rudder and elevator.  Autorotation  
refers to rolling induced by an unstable CL/alpha that occurs only on  
the right side.  There, as alpha increases lift decreases so the wing  
descends resulting in alpha increasing and so on.  On the rising wing,  
alpha is decreasing so lift is increasing so the wing keeps rising.   
The result is a spontaneous, continuous  roll.

This is untrue on the left side but we can and do induce rotation with  
ailerons.  If we want to fix the rules we should probably get rid of  
the autorotation/stall requirement and describe the desired flight  
path, not how to achieve it.  Agree?

Make sense?

Jim


On Oct 16, 2009, at 6:58 AM, Ron Van Putte wrote:

> Jerry's point is that the airplane can't get to the portion of the  
> CL/alpha curve to the right, above the critical alpha.  Too many Gs  
> on the airplane at normal flying speed.
>
> Ron VP
>
> On Oct 16, 2009, at 12:36 AM, James Oddino wrote:
>
>> The way I see it, most of the folks think that the wing is stalled  
>> or it isn't.  This is not the case.  Stalled typically refers to  
>> the portion of the CL/alpha curve to the right, above the critical  
>> alpha.  The CL does not go to zero when alpha exceeds the critical  
>> 15 or so degrees but drops with a relatively low slope.  That means  
>> it is still providing lift.  It can also be at different values on  
>> each panel.  This is what Jerry was talking about when he referred  
>> to stalling the wing asymmetrically.  (See excerpt below).
>>
>> I submit we can create a similar asymmetrical Lift on the left side  
>> of the curve, below the critical angle and produce a SNAP ROLL with  
>> the application of ailerons.  This is probably not a true  
>> autorotation that would occur with rudder and elevator only if we  
>> were on the "stalled" side of the curve, but the resulting airframe  
>> response looks the same.
>>
>> I rest my case, Jim
>>
>> I am not an aeronautical engineer.  Where is Jim Alberico when we  
>> need him?
>>
>> On Oct 15, 2009, at 6:23 PM, Ron Van Putte wrote:
>>
>>> I was busy when this came in and didn't sit down to read it until  
>>> tonight.  I'm an aeronautical engineer and EVERYTHING Jerry wrote  
>>> made sense to me and I'm a picky engineer.  I hope everyone was  
>>> able to wade their way through it and understood what Jerry  
>>> wrote.  He used some technical stuff that may have slowed some  
>>> down, but it was presented in such a way that most R/C aerobatic  
>>> pilots should understand the logic.
>>>
>>> Well done Jerry.
>>>
>>> Ron Van Putte
>>>
>>> On Oct 14, 2009, at 5:12 AM, Budd Engineering wrote:
>>>
>>>> So what are we doing to make the plane present what appears to be  
>>>> a snap roll when we can't actually be stalling the wing  
>>>> asymmetrically to induce autorotation like many claim?
>>
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