CG for Biplane and more control sensitivity

[Dean Pappas]

Hi Paul,
Question 1 Yes, but only if the two wings have equal area.
 
Question 2 If you get completely (and I do mean completely) baffled by the problem, then think about a way to investigate the problem. Have you flown the plane with less throw? How fast is your maximum roll rate? Do you just have way too much roll rate available at 100% ATV?
 

Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of paul
Sent: Thursday, December 08, 2005 4:57 PM
To: discussion at nsrca.org
Subject: Re: CG for Biplane and more control sensitivity


Dean,
    Thanks for the info on the Bipe CG.  Out of curosity, wouldn't the same result be found by independently calculating the 25% point on each wing individually and averaging them ?
    
    Regarding the ailerons - I have never looked that closely at the aileron LE.  Both wings have the same quirk - the aileron LE protrudes ~ 1/32 down near the root for about 2.5 " and about 1/32 up at the center for about 5".  
    What do you think ?
 
Thanks,
Paul
 

----- Original Message ----- 
From: Dean  <mailto:d.pappas at kodeos.com> Pappas 
To: discussion at nsrca.org 
Sent: Thursday, December 08, 2005 3:22 PM
Subject: RE: CG for Biplane and more control sensitivity

Hi Paul, 
It's the wing area weighted average of the 25% (or whatever) MAC of each wing.
If the areas are equal, it is centered between the 25% MAC of the bottom and the 25% MAC of the top. 
If the top wing has, say, double the area of the bottom wing, then it's 2/3 of the way from the 25% MAC of the bottom to the 25% MAC of the top.
 
While I am here: did the throw reduction fix your sensitivity problem?
One other variable is hingeline shape. If the leading edges of the the ailerons protrude above the wing surface this can cause all sorts of issues.
It wasn't likely, so I didn't bother to chime in, before.
later,
Dean
 
 

Dean Pappas 
Sr. Design Engineer 
Kodeos Communications 
111 Corporate Blvd. 
South Plainfield, N.J. 07080 
(908) 222-7817 phone 
(908) 222-2392 fax 
d.pappas at kodeos.com 

-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org]On Behalf Of paul
Sent: Thursday, December 08, 2005 4:00 PM
To: discussion at nsrca.org
Subject: CG for Biplane


    Anyone know how the calculate the CG for a Biplane ?  I expect it is 25-30% of the MAC; but, how do I calculate the MAC for a biplane ?
Thanks,
Paul

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