Thread Tools
Dec 06, 2018, 07:14 PM
Zen in the art of foam
djacob7's Avatar
Mini-HowTo

Split drag rudder


Designed and built a prototype drag rudder for my current project of a B-2 Stealth, 60".
Here are some pics and a video...

Split drag rudder (0 min 48 sec)
Sign up now
to remove ads between posts
Dec 06, 2018, 08:01 PM
Retired CAD guy
birdofplay's Avatar
nice work.
Dec 06, 2018, 09:51 PM
Zen in the art of foam
djacob7's Avatar
Thanks. I hope most folks understand why only half the servo travel is used per side.
Dec 06, 2018, 10:31 PM
Registered User
Pretty slick.

Just a thought, but couldn't you use standard control horns and adjust the servo travel to zero in the closed position and eliminate the need for a spring?
Again, just a thought.

Jim
Dec 06, 2018, 10:35 PM
Zen in the art of foam
djacob7's Avatar
I think you mean using the whole servo travel to open the rudder?
If so, both left and right rudders would move, and we want only one moving at a time.

Quote:
Originally Posted by jcase
Pretty slick.

Just a thought, but couldn't you use standard control horns and adjust the servo travel to zero in the closed position and eliminate the need for a spring?
Again, just a thought.

Jim
Dec 07, 2018, 05:57 AM
gpw
gpw
“There’s no place like Foam”
gpw's Avatar
Cool !!!
Latest blog entry: Lost plans
Dec 07, 2018, 10:40 AM
Registered User
Very cool. Am I missing something or can this NOT be used as a normal rudder? Or, are you planning on a second servo that would move the rudder normally with the drag servo fully extended to the back of the slot?
Dec 07, 2018, 10:57 AM
Registered User
Quote:
Originally Posted by djacob7
I think you mean using the whole servo travel to open the rudder?
If so, both left and right rudders would move, and we want only one moving at a time.
No, actually I was suggesting reducing the one half servo travel that you don't use to zero. This would eliminate the aft travel direction as well as eliminate the need for the slot in the control horn you have and the spring mechanism. Use the same linkage you have from the servo to the control horns but replace yours with standard control horns. Use a clevis's or z-bend and this would give you a no slop lock of the drag rudder in the closed position. Hope that makes sense.

Jim
Dec 07, 2018, 06:00 PM
Build straight - Fly twisty
Whiskers's Avatar
Yup! That's right.
You can set end-points for servo travel, so you'd just need to set it to zero travel on one side.

Or you could use 'pull only' thin wire. They would pull the surfaces open but just go slack when the servo horn tried to 'push.'

Or you could make up telescopic 'pull rods' to do the same job.
Dec 07, 2018, 06:09 PM
Build straight - Fly twisty
Whiskers's Avatar
Quote:
Originally Posted by EvanM
Very cool. Am I missing something or can this NOT be used as a normal rudder? Or, are you planning on a second servo that would move the rudder normally with the drag servo fully extended to the back of the slot?
These things are positioned near the wing tip and provide yaw control by inducing drag on said wing tip when deployed.
They can obviate the need for a vertical surface like the typical fin and rudder. Mainly used in full-size aviation for stealth enhancement.
In models used for cool.
Dec 07, 2018, 06:12 PM
Zen in the art of foam
djacob7's Avatar
Jcase, Whiskers, to set the servo travel to zero on one side would require a programmable Tx?
Would that result in only one servo acting at a time?
So when the right servo arm moves forward, the left won't move?
I'll have to find out how it's done.
I can't see how moving the rudder stick will affect only one servo.
Dec 07, 2018, 07:28 PM
Build straight - Fly twisty
Whiskers's Avatar
Hey! You may be right! In fact I think you are right.
I was thinking about what I did with setting ailerons to have 100% differential.
In that case I had one servo on Ch 1 and the other one on Ch 6. Therefore they could be tuned independently.
Two servos on a Y harness are a different can of worms.
Dec 07, 2018, 07:38 PM
Zen in the art of foam
djacob7's Avatar
Whew! That's a relief hahaha!

Quote:
Originally Posted by Whiskers
Hey! You may be right! In fact I think you are right.
I was thinking about what I did with setting ailerons to have 100% differential.
In that case I had one servo on Ch 1 and the other one on Ch 6. Therefore they could be tuned independently.
Two servos on a Y harness are a different can of worms.
Dec 07, 2018, 07:50 PM
Registered User
Yes with a servo moving each half of the surface how they move then becomes a Tx programming exercise.
In theory in a flying wing it would be possible for the surfaces to act as rudders, ailerons, elevators and air brakes, but not giving 100% effect all at the same time!
Dec 08, 2018, 09:58 AM
Registered User
Quote:
Originally Posted by djacob7
Jcase, Whiskers, to set the servo travel to zero on one side would require a programmable Tx?
Would that result in only one servo acting at a time?
So when the right servo arm moves forward, the left won't move?
I'll have to find out how it's done.
I can't see how moving the rudder stick will affect only one servo.
Sorry, I wasn't even thinking of a Y-harness arrangement. My idea was assuming independent servos for each surface. And as already mentioned, adjusting the travel is done in the Tx.

Jim


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion split airleons as rudder ? ebonbetta Flying Wings 1 Sep 04, 2018 08:28 PM
Question Flying wing with split drag surface on tower for pitch control? kcaldwel Modeling Science 105 Jul 26, 2016 09:38 PM
Question Futaba 7CAP and drag rudders? Supagoat Radios 3 Aug 27, 2007 10:59 AM
Discussion zagnutz + drag rudders rotccapt Flying Wings 3 Jun 28, 2006 12:06 PM
Drag rudders and nurflügels surfimp Modeling Science 18 May 20, 2004 04:41 PM