air drag on wing?  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> RC Airplanes >> Aerodynamics >> air drag on wing?
Page: [1]

Login
Message << Older Topic   Newer Topic >>
air drag on wing? - 6/13/2007 1:09:33 AM   
7snakes


 

Posts: 31
Joined: 3/22/2006
From: Athens, OH, USA
Status: offline 		I have a Nexstar with a CVS cam mounted inline with the cg on the left side of the fuselage under the wing. I have it pointed to the front of the plane and the cam is mounted upright with its edge attached to the fuse. It protrudes apprx. 3 inches from the fuselage. Flight characteristics of the plane have been flyable, but challenging to say the least. Trying to bank to the left usually results in the plane failing to turn and it goes nose up into a steep climb.( Basically almost hovering) Banking to the right does not give problems. I tried to compensate by programming in down elevator with a left bank and the plane generally makes a decent left turn. Maybe it was just the wind direction or speed causing the problem? Or is the left wing stalling from the drag created by the camera? What in all likelyhood is happening? If I mount another cam in the same fashion to the right side , will I get the same failure to turn? What if I have a cam on each side? Will the effects cancel each other and I not have a problem banking, or will I not be able to bank in any direction? Could the problem be one of just cg issues laterally? I have gotten some ok footage with these cams when they are mounted flat up against the fuse videoing straight out to the sides. The plane flies fine without any cameras. It flies fine with 1 or 2 cameras on each side if they are mounted flat up against the fuse. I know it wouldn't be laterally balanced with 1 camera on the side-still it flies fine.(trying to get forward facing video) The problem arises when the cam is mounted on its edge facing forward. It is like I have no aileron response to turning left. I programmed in some down trim to the elevator when banking to the left with a switch on the tx. It seems to help considerably. Banking to the right is not a problem. I want to try forward facing cams on both sides at the same time, but am hesitant I will not be able to control seeing how the left sided mount worked. If it was a cg issue, wouldn't it present problems with the cams also mounted sideways flat up against the fuse? (no-it flew fine with 1 or 2 mounted this way. It just seems to not want to turn left and the nose rises so the plane appears headed for a stall.
Another thing I was thinking. In straight flight air moving over and under the left wing is really only being deflected on the underside by the camera. When input is given to bank left, now 2 surfaces are protruding on the left wing-a.the aileron is going up and b. the camera under the wing is down(2 projections, 1 above the wing and 1 under) The right wing only has 1 projection in the left bank and that is the aileron going down.
       Post #: 1

RE: air drag on wing? - 6/14/2007 6:28:15 PM   
Tall Paul



Posts: 4693
Joined: 6/23/2002
From: Palmdale, CA, USA
Status: offline 		Try adding rudder (or install a rudder) and coordinate that with the ailerons.

_____________________________

Sparky Paul
http://www.angelfire.com/indie/aerostuff

(in reply to 7snakes)
       Post #: 2

RE: air drag on wing? - 6/15/2007 2:50:37 AM   
BMatthews



Posts: 9005
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline 		I can see two things going on here. First of all try rudder instead of aileron like Paul suggested above for this drag trim change. Rudder is useful for more than just taxiing... The drag of the camera is inducing more of a yawing effect and rudder is the right tool to counter it.

Secondly if the camera and housing (and battery?) is more than a couple of ounces in weight then you'll want to install a counter weight on the other side.

< Message edited by BMatthews -- 6/15/2007 2:51:40 AM >

_____________________________

Witty saying to be plagarized shortly.....

(in reply to Tall Paul)
       Post #: 3

Page:   [1]
All Forums >> RC Airplanes >> Aerodynamics >> air drag on wing?
Page: [1]





Jump to:


Google 



Search | Marketplace | Event Calendar | Local Clubs | Magazine | Product Ratings | New Products | Discussion Forums

Photo Gallery | Member Video Posts | RCU Video Gallery | Instructor Search | Field|Track|Marina Search

Advertisers | Hobby Vendor Resources | Rate Manufacturers | Sign In/Sign Up

SITE MAP!   : :   FORUM RULES

© 2001 - 2007 24-7 RC, LLC, all rights reserved.

Charities we support that also need your help
Yorkie Rescue | Humane Society | ASPCA | Crohn's-Colitis America

Kaango.com Classifieds

0.781RCU5