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Old Jul 04, 2002, 08:06 PM
KZ RIDER
raythomas's Avatar
Confederate States of America
Joined Nov 2001
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Bird-E-Dog is wigging out! What to do???

I built one of the Bird-E-Dog planes about a month back. It's been crazy around here so I just today got a chance to fly it. The problem is that the rudder doesn't have hardly any authority when the motor is not turning and blowing air past it. Flying around at cruise or wide open throttle, its fine, but when you chop the throttle to land the rudder just doesn't turn the plane like it should. I built it just like the plans, and I have the throw adjusted where its bumping the inside of each elevator half, still no luck. Any ideas?? Thanks Ray

Here is a pic. As you can see it has plenty of vertical stab, just not alot of rudder area.

http://www.rcgroups.com/cgi-bin/phot...x.pl?photo=350
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Last edited by raythomas; Jul 04, 2002 at 08:11 PM.
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Old Jul 04, 2002, 08:35 PM
ὅπερ ἔδει δεῖξαι
Gerald's Avatar
Joined May 2000
3,339 Posts
Great looking Bird Dog Ray! You're right there's not a lot of rudder area there. It could be that when you cut the power for landing that you are slowing the plane down and pitching the nose up at a higher angle of attack to bleed off airspeed. The wing and fuselage may be blocking some of the airflow over the rudder when the tail is drooping lower like that. You might try a faster landing approach or fly it all the way onto the ground with the prop still turning at low rpm without flaring too soon.
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Old Jul 05, 2002, 02:51 AM
KZ RIDER
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Your right, I did have to land with power on to have control over the plane, but It wasn't in a nose high attitude when I was landing. In fact when I first noticed the sluggish rudder was when I was decending, in a shallow dive. It has almost no rudder response unless the motor is turning pretty fast. I guess to put some air past it. Ray
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Old Jul 05, 2002, 07:43 AM
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Martin Irvine's Avatar
Canada, ON, Kingston
Joined Aug 2000
2,038 Posts
The rudder LOOKS adequate. Hmmm.....
Where is the CG? Perhaps it is a little forward. Can you move it back a bit and see if that helps?
The elevators cut in pretty close. What is the actual throw at the rudder trailing edge? How many degrees?
The dihedral looks fairly low. Do you know how many degrees it is? Too little and it won't turn the way it should without ailerons.

Looks nice in spite of the problem. Where is the plan from?

Cheers,

Martin
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Old Jul 05, 2002, 02:10 PM
Always looking UP
FANMAN's Avatar
Lilburn, Georgia, USA
Joined Nov 2000
2,361 Posts
Too small

I have to disagree that its OK. If the rudder isnt responsive enough, power off, then it needs more surface.

Idea here, on my old Kyosho EP cessna, I wasnt happy with the rudder response, so I added a 3/8" strip to the back of the rudder, and all was solved. Please dont mess up the beautiful job you've done, but investigate the possibility of temporarily adding (something) back there, and take it for a test fly, you wont be doing anything `dangerous' ........

I am wanting to do a `one of' laser cut, and I'm glad this was mentioned.......
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Old Jul 05, 2002, 03:43 PM
KZ RIDER
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The plans were featured in Model Aviation a few months back. No kit, I had to hand cut every piece. I love building from scratch. To me its more rewarding to know that all I started with was a pile of sticks and sheets and made the plane myself. Fanman, I'll try and see about adding some more area to the rudder. I'm trying to figure out how to do it so it still looks stock. The plane is perfect in its present state. I'll see. Thanks Ray
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Old Jul 08, 2002, 10:41 PM
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Granby, CT, USA
Joined Jan 2001
953 Posts
Bird-E-Dog

I finished mine a couple of weeks ago, and I couldn't leave 'well enough' alone, so while I was studying the plans I reformatted the empennage to be more scale, mostly by moving the hinge lines more towards they scale locations, and in doing so I also shortened the fuselage an inch at the tailpost. I will not be able to fly the model until mid-August, so I can't offer comments about its control response in unpowered mode. I concur with the CG advice. That might be the easiest thing to do, and with this model dead easy, move the battery back a bit.
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Old Jul 08, 2002, 10:55 PM
KZ RIDER
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If I was having trouble with a pitching problem, like the elevator not having enough authority I would say yes it could be a CG problem. But I just don't see how moving the CG is going to help an airplane turning with rudder turn better?? Can anybody explain? Thanks Ray
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Old Jul 11, 2002, 10:23 AM
slow but inefficient
Ron Williams's Avatar
Riverhead NY USA
Joined Dec 2000
3,097 Posts
Bigger Rudder

Hi Ray -

I was looking at a full sized Bird Dog this last weekend and it has a much bigger rudder with the top counter balanced. That rudder on yours looks way too small. Time for a little rebuild? There should be a picture or three-view somewhere on the Web.

Ron
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Old Jul 11, 2002, 01:39 PM
KZ RIDER
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I don't understand it, The fellow that designed this plane had about 10 or 12 friends that copied his plans and built one for themselves. And they all rave about how well they fly. And I build mine from the same set of plans, so what gives?? It looks like at least one or two of those fellows would have had a turning problem, but yet they all say they fly great. Ray
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Old Jul 11, 2002, 04:45 PM
Always looking UP
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Lilburn, Georgia, USA
Joined Nov 2000
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L-19

Per request, I am designing one right now, and yes the feathers are much larger

Based on my review of the plan described above, it doesn't look like the parts where very sofisticated, nor very accurate

I'm going to size mine at 54" span, thats 1/8 scale, and hope to do a GIANT 1/4 scale @ 108" wingspan, all laser cut, snap fit, interlocking, quick build parts
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Old Jul 16, 2002, 05:09 PM
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Lilburn, Georgia, USA
Joined Nov 2000
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Serious Bird Dog!

RTB (Ready to build) real soon
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