My Upline needs more than just rudder  
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All Forums >> RC Airplanes >> Aerodynamics >> My Upline needs more than just rudder
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My Upline needs more than just rudder - 12/1/2007 4:33:42 PM   
Flyboy1958



Posts: 473
Joined: 10/20/2002
From: Somewhere, PA, USA
Status: offline 		I have a Cap 232 that just flys awesome. It is balanced just right for me and tracks straight as an arrow with no trim needed. Since I got the CG right and and I am just in the trimming stage of setting this thing up I figured the next step is thrust adjustment. When I fly 3/4 to full pwr. straight and level and cut the throttle, it continues straight and level for several seconds and then starts a gradual descent. I figured my up/down thrust must be right on. The next thing I did was fly from 3/4 pwr. straight and level with a pull to an up line. It initially tracked prefect for about 100 feet, I then had to start to add right rudder which is typical, so I guess I need a little right thrust in my engine setup. This is the part I am confused about, as I started to add right rudder, the plane started a gradual push to the belly with a slight roll to the left. Now what's what's that mean? My lateral balance might be off just a bit, so I do have to retest that again, I noticed that in a loop the left wing does come out just a touch low now and then. Any aditional thoughts?
       Post #: 1

RE: My Upline needs more than just rudder - 12/1/2007 5:35:59 PM   
Lomcevak Duck



Posts: 955
Joined: 2/22/2004
From: Warner Robins, GA, USA
Status: offline 		I think most Caps have a tendency to tuck under with rudder input.

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(in reply to Flyboy1958)
       Post #: 2

RE: My Upline needs more than just rudder - 12/1/2007 6:31:10 PM   
dbacque


 

Posts: 362
Joined: 6/3/2005
From: Houston, TX, USA
Status: offline 		Test for both lateral balance and rudder coupling.

Lateral balance - Trim out for straight and level flight, roll inverted and observe roll trim. If the plane tends to roll left when inverted, add weight to the left wing tip. If it rolls right when inverted, add weight to the right. A lateral balance problem will cause the roll problem you describe in loops.

Rudder coupling - In level flight apply rudder, observe any pitch and roll tendencies. Knife edge is an even better test. Use mixing if you have it to correct the coupling to where you can hold knife edge with only rudder input.

After both of these, repeat your vertical climb test. You should see improvement.

Dave

(in reply to Lomcevak Duck)
       Post #: 3

RE: My Upline needs more than just rudder - 12/1/2007 6:51:59 PM   
Flyboy1958



Posts: 473
Joined: 10/20/2002
From: Somewhere, PA, USA
Status: offline 		Thanks, maybe it is just a Cap thing. It's going to be a while Im sure before I am able to test fly it again since we are into winter weather with a lot of wind lately, but I will try to get the lateral balance down first before I continue and start making any adjustments. I did happen to test by flying level flight and applying only rudder and it did roll and dive in the direction of the applyed rudder. I thought it was quite extreme as well. First things first. Thanks

(in reply to dbacque)
       Post #: 4

RE: My Upline needs more than just rudder - 12/2/2007 6:48:56 PM   
Steve Steinbring


 

Posts: 242
Joined: 7/17/2007
From: Homestead, FL, USA
Status: offline 		My thoughts are that on your upline because the airspeed is bleeding off torque and P factor will have more effect. Your trim requirements will change as the flight regime changes. As far as the loop with a sometimes low wing at completion, could be inadvertant control mixing ie. adding a small amount of aileron.

(in reply to Flyboy1958)
       Post #: 5

RE: My Upline needs more than just rudder - 12/2/2007 9:29:38 PM   
da Rock



Posts: 6370
Joined: 10/11/2005
From: western, NC, USA
Status: offline
quote:

ORIGINAL: Flyboy1958

Thanks, maybe it is just a Cap thing. It's going to be a while Im sure before I am able to test fly it again since we are into winter weather with a lot of wind lately, but I will try to get the lateral balance down first before I continue and start making any adjustments. I did happen to test by flying level flight and applying only rudder and it did roll and dive in the direction of the applyed rudder. I thought it was quite extreme as well. First things first. Thanks



I've had a couple and they rudder couple strongly. Just as you saw. They're pretty bad in the knife edge too.

Nothing I'd flown up until then had made me put mix functions into the radio for any airplane before. The first CAP had me setting up a couple of mixes on that radio within a week.

(in reply to Flyboy1958)
       Post #: 6

RE: My Upline needs more than just rudder - 12/3/2007 3:22:33 PM   
Flyboy1958



Posts: 473
Joined: 10/20/2002
From: Somewhere, PA, USA
Status: offline 		Good, OK well until I can get this thing back in the air, I won't have any flight reports. I am going to follow Peter Goldsmiths trim sequence so I get it right. Thanks

(in reply to da Rock)
       Post #: 7

RE: My Upline needs more than just rudder - 12/31/2007 9:23:36 PM   
zbo2


 

Posts: 84
Joined: 10/15/2007
From: Newfield, NJ, USA
Status: offline 		i'd like to see a sticky that shows the effects of things like right and left thrust and up and down thrust and the things you need to do on the inital flights to get a plane trimmed correctly. i've been around for a while but have never really had all that info stick in my head. i have a chipmonk that on the up line will want to roll left. i'd like to be able to go to a sticky that will help me to make the adjustments to get it trimmed correctly. if i do it that way it will stick in my mind. what do you think...can you guys with that knowledge help those of us like me out?

< Message edited by zbo2 -- 12/31/2007 9:25:09 PM >

(in reply to Flyboy1958)
       Post #: 8

RE: My Upline needs more than just rudder - 1/20/2008 10:21:54 PM   
gyrocptr


 

Posts: 36
Joined: 7/9/2006
From: Neenah, WI, USA
Status: offline 		This chart may be of help.

http://www.palosrc.com/instructors/trim-chrt.htm

(in reply to zbo2)
       Post #: 9

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