HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 09, 2012, 02:36 PM
Registered User
campbellj's Avatar
United States, FL, Port St Lucie
Joined Jan 2011
153 Posts
Well I got my RP maidened today. Weather was great and had absolutely no problems! The first flight only lasted 15 minutes but I got close to 30 on my second battery. This plane flys great! I centered my sub trims last night and today I barely needed but a couple clicks on the rudder. I was so surprised how great it flew out of the box. It took a couple minutes to get used to slower roll rates than I'm used to though. I only used flaps, some expo, and the elevator/rudder mix from Lizardman's setup. Also launch mode and flipped to cruise after. The only thing that could have made it any better would have been having a lawn chair to sit and relax in!

It might need one adjustment though, I don't know maybe its normal, but when using the elevator the whole tail will flex from side to side. One way for up elevator and the other way for down. Is the tail flex just a normal weak spot or could the pushrod be binding? I did notice when using the elevator in the air the flex would have a yaw effect on the plane as if I was giving rudder input. It was very very minimal but enough to notice and wonder what was going on. i finally put 2 and 2 together, so I figured I would ask. Thanks everyone!!
campbellj is offline Find More Posts by campbellj
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 09, 2012, 03:14 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
2,950 Posts
There are 2 main reasons why elevator action causes a deflection of the rudder. One is because the elevator horn is mounted too far from the center line. It is easy to move it more inboard. The other is because of the excessive fuselage flex in the narrow part ahead of the vertical stabilizer. Removing the fiberglass spar from the underside of the fuselage and replacing it with an arrow shaft will take care of that. Also it is important to pull out the push rods and sand the sticky black coating off of them.

Doing these things will get rid of the excess movement, and make both the elevator and rudder more effective.
Jovanx is offline Find More Posts by Jovanx
Reply With Quote
Old Dec 09, 2012, 03:39 PM
A geriatric flier
Watdazit's Avatar
Australia, NSW, Braidwood
Joined Nov 2008
828 Posts
Quote:
Originally Posted by Jovanx View Post
..........Removing the fiberglass spar from the underside of the fuselage and replacing it with an arrow shaft will take care of that. ...........
Do you take the feathers off.....sorry couldn't resist that
Watdazit is online now Find More Posts by Watdazit
Reply With Quote
Old Dec 09, 2012, 03:41 PM
Closed Account
Joined Aug 2011
530 Posts
...
Radio.Active is offline Find More Posts by Radio.Active
Last edited by Radio.Active; Jun 13, 2013 at 10:29 AM.
Reply With Quote
Old Dec 09, 2012, 03:48 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
2,950 Posts
Quote:
Originally Posted by Watdazit View Post
Do you take the feathers off.....sorry couldn't resist that
Actually, yes I did. However they grew back quickly and the bird thanked me over and over for her improved flying abilities.
Jovanx is offline Find More Posts by Jovanx
Reply With Quote
Old Dec 09, 2012, 03:50 PM
Closed Account
Joined Aug 2011
530 Posts
...
Radio.Active is offline Find More Posts by Radio.Active
Last edited by Radio.Active; Jun 13, 2013 at 10:29 AM.
Reply With Quote
Old Dec 09, 2012, 06:44 PM
Registered User
campbellj's Avatar
United States, FL, Port St Lucie
Joined Jan 2011
153 Posts
Sounds fairly easy enough to do. I will stop one day this week and pick up a CF arrow shaft. I still got quite a bit of 2.0mm CF Rod left from reinforcing my T-28. Plenty enough for the elevator and to shove a piece up in the stab. I searched through all the pictures in this thread, and the radian thread but didnt see a picture of the control horn any more inboard than mine is. Maybe I skipped over it while looking. Should I just move it over as far as it will go?
campbellj is offline Find More Posts by campbellj
Reply With Quote
Old Dec 09, 2012, 07:07 PM
Registered User
campbellj's Avatar
United States, FL, Port St Lucie
Joined Jan 2011
153 Posts
Also I was looking through Radio.Active's photos of all the reinforcement mods on the radians and seen something called a decalage mod. I'm new to all the terminology but is this more or less the angle of the stab compared to the wing? Is this mod something that's necessary after installing the CF arrow shaft? It seems like the arrow shaft really straightens out the fuse, so that's another question that just popped in my head. Thanks!
campbellj is offline Find More Posts by campbellj
Reply With Quote
Old Dec 09, 2012, 07:29 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
2,950 Posts
Quote:
Originally Posted by campbellj View Post
Sounds fairly easy enough to do. I will stop one day this week and pick up a CF arrow shaft. I still got quite a bit of 2.0mm CF Rod left from reinforcing my T-28. Plenty enough for the elevator and to shove a piece up in the stab. I searched through all the pictures in this thread, and the radian thread but didnt see a picture of the control horn any more inboard than mine is. Maybe I skipped over it while looking. Should I just move it over as far as it will go?
Here are a few pictures of the moved control horn, and the elevator stiffening method. It is 1/16" steel rod. Although it looks like copper it is copper-plated steel. A slot is cut into the trailing edge of the elevator so the rod is 2/3 embedded and 1/3 exposed. Music wire would work fine.
Jovanx is offline Find More Posts by Jovanx
Reply With Quote
Old Dec 09, 2012, 08:23 PM
Registered User
campbellj's Avatar
United States, FL, Port St Lucie
Joined Jan 2011
153 Posts
Thanks for the pics! I actually have some music wire too I can use in the same spot, it might not be 1/16 thick though but it's fairly close.

Should CG still be ok at 77mm or should I move it back some?
campbellj is offline Find More Posts by campbellj
Reply With Quote
Old Dec 09, 2012, 08:41 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
2,950 Posts
If you use a wire less than 1/16" there would probably be no point doing the mod. If anything I would err on the side of something heavier. The purpose is to transfer the torque from the horn side to the other side, and I think 1/16" is a bare minimum. Considering that many people end up putting dead weight on the tail anyway, I would not scrimp on the size and stiffness of that wire.
Jovanx is offline Find More Posts by Jovanx
Reply With Quote
Old Dec 09, 2012, 08:52 PM
Registered User
campbellj's Avatar
United States, FL, Port St Lucie
Joined Jan 2011
153 Posts
Fair enough, I just went and checked and the thickest music wire I have is .047. 1/16 is .062, I remember seeing some that thick at hobby lobby the day I picked some up. It won't take much effort to go back and get the proper stuff if not even a little thicker.
campbellj is offline Find More Posts by campbellj
Reply With Quote
Old Dec 10, 2012, 03:46 PM
Registered User
Joined Feb 2006
579 Posts
Quote:
Originally Posted by campbellj View Post
Also I was looking through Radio.Active's photos of all the reinforcement mods on the radians and seen something called a decalage mod. I'm new to all the terminology but is this more or less the angle of the stab compared to the wing? Is this mod something that's necessary after installing the CF arrow shaft? It seems like the arrow shaft really straightens out the fuse, so that's another question that just popped in my head. Thanks!
The word "decalage" has about a half dozen different meanings. The angle of the stab compared to the wing is only one of those meanings and even that is confusing because there are several difference reference angles for a wing (e.g., chord line, angle of the flat bottom, zero-lift line, etc.) The decalage mod is not necessary. The plane can be trimmed out by adjusting the elevator trim and leaving the stab angle alone.
williamson is offline Find More Posts by williamson
Reply With Quote
Old Dec 10, 2012, 05:03 PM
Tossing planes into the snow
Canada, BC, Smithers
Joined Nov 2011
2,950 Posts
Quote:
Originally Posted by williamson View Post
... and even that is confusing because there are several difference reference angles for a wing (e.g., chord line, angle of the flat bottom, zero-lift line, etc.)
To make it even more confusing, the Radian Pro has a significant amount of washout, which means the angles are different at the root, the midpoint, and the tip. The "proof-in-the-pudding" approach makes more sense than trying to measure angles.

Let's suppose that after a lot of flying and experimenting with different CG locations, you eventually got it the way you want it to fly, and it did what you want in the dive test. If it took a bunch of down-elevator trim to make that happen, you might want to consider changing the angle of the stab. Mine takes some down trim, but not enough for me to worry about. If I was a competition flier, it might matter.
Jovanx is offline Find More Posts by Jovanx
Reply With Quote
Old Dec 10, 2012, 05:04 PM
Gopher huntin' stick jockey
turboparker's Avatar
East Bethel, MN USA
Joined Jul 2009
11,660 Posts
The problem with trimming is that it is airspeed-dependent. As Jovanx noted - if the stab is off far enough to require a fair amount of down elevator trim, I think it's best to align it.

Joel
turboparker is offline Find More Posts by turboparker
RCG Plus Member
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Rave New Parkzone Radian Pro-discussion thread!!! lightspeeddud Electric Sailplanes 3675 Feb 19, 2014 02:58 AM
Discussion Official Radian Pro Thread Magnumb Parkflyers 14 Apr 10, 2011 10:56 PM
Gallery Parkzone Radian Pro Video bakon Electric Sailplanes 6 Mar 11, 2011 05:21 PM
New Product Parkzone Radian Pro bakon Electric Plane Talk 24 Oct 01, 2010 01:39 AM
Discussion Parkzone Radian Pro $229.99 BnF preorder Tekwip Hot Online Deals 10 Sep 29, 2010 04:35 PM