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calculating Va
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bmwebb(at)cox.net
Guest

Posted: Thu Mar 02, 2006 7:48 pm Post subject: calculating Va

Speaking of the motor mount, I had heard that Sean Tuckers Bi-plane was G

limited only by the motor mount. Otherwise, I guess even he couldn't break

the airframe.



When pondering, don't forget the whole airframe, not just the wings.



Bradley



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jdmcbean(at)cableone.net
Guest

Posted: Thu Mar 02, 2006 8:02 pm Post subject: calculating Va

Al,

	You must have been speaking with Dave Snell.. Great guy.. Although the

aircraft wings are supporting a lighter load.. say 1 pilot, low fuel, no

baggage etc... The engine mount is still carrying the same weight...



FYI.. The engine mount, baggage area even the horizontal tail surface was

load tested.



Fly Safe !!

John McBean

www.sportplanellc.com

"The Sky is not the Limit...  It's a Playground"



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smokey_bear_40220(at)yaho
Guest

Posted: Thu Mar 02, 2006 11:50 pm Post subject: calculating Va

Clem,



Never a bad question.



Some of us skin a cat front to back, some back to

front.  If John's example didn't go your direction,

try this one.  (Mom always said I was a bit backward)



Suppose a plane has a gross weight of 1000 lbs.  At X

speed it can just lift 3.8 G's or 3,800 lbs before

stalling.  So X = VA speed at gross weight.



If you loaded the plane to only 760 lbs and flew it at

the same X speed, it could still lift 3,800 lbs, but

that would take 5 G's to reach 3,800 lbs of lift  and

stall it.



 WT    G's   Wing load

1000 x 3.8 = 3,800 lbs

760  x 5   = 3,800 lbs



The lighter the weight, the more G's you can pull at

the same speed and it is the G's that cause the

overload because the engine (and you, etc) still weigh

the same.  So you have to slow down to keep from

exceeding 3.8 G's before stalling at lower weights.



760 lbs x 3.8 G's = 2,888 lbs of lift



At 760 lbs, you need to slow down so that your wing

can only generate 2,888 lbs of lift before stalling or

you can exceed 3.8 G's.



 	  Quote: 	
		  From this you should see that it is not the wings that

will fail on a Fox.  They can lift gross weight at the
	


designed G limit.  But the other components can exceed

their G'limit before the wings stall, let alone fail,

at below gross weight, or higher than VA speeds.



Likewise in the rock and string example, the lighter

rock (plane) can be spun to a higher G limit before

the string (wing) breaks.  The G limit of the rock,

not the string is the limiting factor.



Hope that helps because simple is all I can do

anymore.  



Kurt S. S-5



--- jdmcbean <jdmcbean(at)cableone.net> wrote:



 	  Quote: 	
		   Clem,

 	Lets see if we can help...........

 

 This will be very simplified:  We know that the wing

 stalls at a given angle of attack not airspeed......

 

 Fly Safe !!

 John McBean

 www.sportplanellc.com

 "The Sky is not the Limit...  It's a Playground"

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smokey_bear_40220(at)yaho
Guest

Posted: Fri Mar 03, 2006 12:15 am Post subject: calculating Va

Michel,



I think the point is that you will reach your limit

before the Fox will, unless you are a fighter pilot. 

After all, we are up there for fun, right?  If it

isn't fun, slow down, or go down and wait until it is

nicer.



And you are right about my having to work at it.  For

work they give me a 2.5 G plane?  I flew around to a

completely different country to avoid clear air

turbulence last year, because I had to hold myself

down in the seat to go thru it.  Worst I had seen in

many years and I wasn't about to go thru it at any

speed.



Kurt S.



--- Michel Verheughe <michel(at)online.no> wrote:

 	  Quote: 	
		  

 Hello Kurt,

 

 On Mar 2, 2006, at 12:29 AM, kurt schrader wrote:

 

 > In the Fox, I slow down when it scares me.

 

 So do I! But I was hoping for a slightly more

 descriptive experience..........

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Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Fri Mar 03, 2006 1:36 am Post subject: calculating Va

On Mar 2, 2006, at 11:12 PM, Bradley M Webb wrote:

 	  Quote: 	
		   Isn't that the real point of a forum such as this?

Of course, Bradly: Learning and enjoying it!
	




On Mar 3, 2006, at 12:39 AM, Lowell Fitt wrote:

 	  Quote: 	
		   I think the Kitfox is a fine airplane, well designed and engineered.

So do I, my dear Lowell "Alfred E. Neuman" Fitt!  
	


Be happy, don't worry!



On Mar 3, 2006, at 9:13 AM, kurt schrader wrote:

 	  Quote: 	
		   I think the point is that you will reach your limit before the Fox 

 will.

That is, actually, the kind of answer I was looking for, Kurt. If I am 
	


the weakest link, I know I won't put myself in turbulence danger 

because my tolerance is very low, indeed. It also matches my  opinion 

about sailing: Any modern sailboat will take much more than any crew 

will. As an unfortunate result, life are lost at sea because vessels 

are abandoned while they are found still floating after the storm. We 

are the weakest link but we must learn to keep our head cool when the 

sh... hum, turbulence ,,, hits the fan!



Cheers,

Michel



do not archive

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_________________
Kitfox 3 - Jabiru 2200

morid(at)northland.lib.mi
Guest

Posted: Fri Mar 03, 2006 4:20 am Post subject: calculating Va

Good one Kurt.  Cleared it all right up for me.

Thanks for taking the time.

Deke



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