HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Mar 30, 2012, 04:20 PM
Standing Athwart History
roo_ster's Avatar
United States, TX, Dallas
Joined Mar 2011
641 Posts
Discussion
Control Surface Stiffening on the Cheap

Howdy:

I built my first scratch-build the other day and have a question about stiffening up control surfaces on the cheap. Here is the link to my first plane:
http://www.rcgroups.com/forums/showthread.php?t=1622608

When I go into a power-on dive and do a hard pull out, I get roll/rotational movement. I suspect this is because the elevator is flexing on the side opposite the control horn. I don;t get this under less stressful conditions.

Here is a top-down view showing the elevator:


FTR, it is a FFF/Bluecor build.

I had a few thoughts:
1. Balsa elevator, 3/16" (this seems sorta pricey)
2. Bamboo skewer along trailing edge & maybe hinge/leading edge of elevator.
3. Wrap elevator in Extreme Tape.
4. Bamboo skewer embedded in top of elevator, at an angle.

Any of ya'll have some cheap tricks to lick this problem?
roo_ster is offline Find More Posts by roo_ster
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 30, 2012, 05:18 PM
Registered User
Joined Feb 2007
3,657 Posts
Which way does it roll? It might be something other than elevon flex as they both ought to flex the same amount. Are you sure they are at the same angle when full up. My thought might be torque roll or something else. Does it do it when you are pulling up out of a dive at half or no throttle? If not, it may not be flex. But, l am sure someone more knowledgeable here will help.
tymbrewolf is offline Find More Posts by tymbrewolf
Reply With Quote
Old Mar 30, 2012, 05:26 PM
Standing Athwart History
roo_ster's Avatar
United States, TX, Dallas
Joined Mar 2011
641 Posts
Quote:
Originally Posted by tymbrewolf View Post
Which way does it roll? It might be something other than elevon flex as they both ought to flex the same amount. Are you sure they are at the same angle when full up. My thought might be torque roll or something else. Does it do it when you are pulling up out of a dive at half or no throttle? If not, it may not be flex. But, l am sure someone more knowledgeable here will help.
No elevons. Throttle, elevator, ailerons. My problem is with the elevator, though the ailerons may also flex. I suspect aileron flexing coming out of a dive is not the issue.

I get no/little torque roll on the model, even if I am so impertinent to launch on WOT. Not sure why.

Twists off to the right.
roo_ster is offline Find More Posts by roo_ster
Reply With Quote
Old Mar 30, 2012, 05:55 PM
treefinder
springer's Avatar
SE MI
Joined Oct 2004
9,944 Posts
If I'm looking at it right, your twist would make it roll to the left if elevator is flexing. Are you sure you aren't adding in a bit of aileron inadvertantly? I tend to do that stuff, don't quite pull straight back. Also, you seem to have an awful lot of reflex in the ailerons, do you need that to fly?
springer is offline Find More Posts by springer
RCG Plus Member
Old Mar 30, 2012, 06:29 PM
Standing Athwart History
roo_ster's Avatar
United States, TX, Dallas
Joined Mar 2011
641 Posts
Quote:
Originally Posted by springer View Post
If I'm looking at it right, your twist would make it roll to the left if elevator is flexing. Are you sure you aren't adding in a bit of aileron inadvertantly? I tend to do that stuff, don't quite pull straight back. Also, you seem to have an awful lot of reflex in the ailerons, do you need that to fly?
I forgot to turn off the spolierons after landing. Help with high-A & bring it to a crawl when landing. Normally, zero reflex.

Maybe I am inputting ail along with el.
roo_ster is offline Find More Posts by roo_ster
Reply With Quote
Old Mar 31, 2012, 01:01 AM
Registered User
Joined Feb 2007
3,657 Posts
Sorry. Read elevons. Didn't even see the elevator. I agree with springer. With the horn on the left side one would think that would get full flexion so full up would be roll left. And the reflex in the ailerons is what led me to see them as elevons as they looked left up on purpose. In any case, my advice on handling on 1/2 power or off power would still be sound in that does wot, 1/2 or off make any difference on roll. One could also switch the aileron channel to the rudder to see if it made a difference as it is easy to pull a little to the right if right handed in quick moment. You could also have a little bit of twist in your tail group or your wing. High speeds take little movements to make big differences. Keep messing, it could just be some aileron linkage slop too.
tymbrewolf is offline Find More Posts by tymbrewolf
Reply With Quote
Old Mar 31, 2012, 11:13 AM
Registered User
North Kent, England UK
Joined Jan 2005
301 Posts
I have used bailing straps, the kind they put round bundles of wood or large boxes. Cut a strip to the thickness of the elevator then cut the elevator lengthways and glue back together. I use UHU Por but whatever you are using should do.

JimW
JimW is offline Find More Posts by JimW
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold Great Planes AccuThrow Control Surface Deflection Meter Dr. J Aircraft - General - Miscellaneous (FS/W) 2 Mar 13, 2012 11:12 PM
Question Frequency control for surface vehicles Andy W SEFF 2012 6 Mar 12, 2012 05:00 PM
Discussion How would you set up control surfaces on a lifting body glider? danpass Electric Plane Talk 8 Dec 02, 2011 06:35 PM
Discussion Installing hinges on foamy control surfaces UlteriorModem Foamies (Kits) 5 Oct 22, 2011 12:57 PM
Wanted Looking for a control surface throw meter INCARUS Aircraft - General - Miscellaneous (FS/W) 2 Oct 11, 2011 08:24 PM