HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Feb 16, 2012, 03:47 PM
Registered User
Joined Oct 2004
2,770 Posts
Those are spoilers, you can see them in action also on several swing wing fighters, and on large planes. They disrupt lift on the wing inside the turn, making it drop, and have the added advantage of increasing drag on the wing inside the turn, so there is no adverse yaw. They also work much better at slower speeds, when common ailerons lose efficiency.
Brandano is offline Find More Posts by Brandano
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 16, 2012, 04:59 PM
Registered User
p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
1,243 Posts
Quote:
Originally Posted by Brandano View Post
Those are spoilers, you can see them in action also on several swing wing fighters, and on large planes. They disrupt lift on the wing inside the turn, making it drop, and have the added advantage of increasing drag on the wing inside the turn, so there is no adverse yaw. They also work much better at slower speeds, when common ailerons lose efficiency.
Spoilers can be used in conjunction with other flight controls for yaw control. You have to look closely at the other control surfaces to see how they react with spoiler movements.
RcPowers has it right with his 3 axis gyro tailless design. His design uses a modified fuselage and flight controls to make all this work. The plane looks a little loofty while flying. Could be because of slow reaction times of his stabiliztion system. He has to manually change the control rates during varying speeds.
To bad a computerized system like a quadcopter was not developed for an aircraft. Who knows what plane designs could have been developed with it..
p901P901 is online now Find More Posts by p901P901
Last edited by p901P901; Feb 16, 2012 at 05:06 PM.
Reply With Quote
Old Feb 16, 2012, 05:04 PM
Registered User
Joined Oct 2004
2,770 Posts
Yep, if you have spoilers AND ailerons, flaperons or tailerons you can lift the spoiler while dropping the aileron and this will keep lift on that wing pretty constant (with good mixing) but increase drag on that wing and cause the plane to yaw towards it. This gives you control, but not stability. In order for the plane to be stable you need to add some device that controls sideslip and adjusts yaw controls to minimise it. With the proper control scheme you can make a tailless wing that is unspinnable... as long as the control computer still runs. It does not erquire a lot of CPU either, a microcontroller could most probably handle it.
Brandano is offline Find More Posts by Brandano
Reply With Quote
Old Feb 17, 2012, 08:17 AM
Registered User
p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
1,243 Posts
X-47b

Ive been thinking of building one of these and working on a control system. I have seen this B2 http://www.rchobbyhome.com/index.php...oducts_id=1493 from LX. The LX B2 does use drag rudders but the X-47B with shorter wings may have a control issue using this design.
Looking at this http://www.rcmartnews.com/news_files...ruction-V2.pdf and trying to figure out how to use mutiple control surface movements for control. CH5 gain control can be used for control throws. All flight controls will be like the real X-47B.
Looks like someone built one:
RC EDF X-47B maiden flight (4 min 49 sec)
What was used for control??
p901P901 is online now Find More Posts by p901P901
Last edited by p901P901; Feb 17, 2012 at 06:03 PM.
Reply With Quote
Old Feb 17, 2012, 12:34 PM
Registered User
Joined Oct 2004
2,770 Posts
As I mentioned earlier, it might even be possible to create some form of control system by hacking a servo and adding a potentiometer controlled by a vane in series with the servo's own. This would effectively shift the servo's centering signal, and have it chase the deflection.
Brandano is offline Find More Posts by Brandano
Reply With Quote
Old Feb 17, 2012, 04:05 PM
Registered User
p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
1,243 Posts
Quote:
Originally Posted by Brandano View Post
As I mentioned earlier, it might even be possible to create some form of control system by hacking a servo and adding a potentiometer controlled by a vane in series with the servo's own. This would effectively shift the servo's centering signal, and have it chase the deflection.
That is what a gyro does
p901P901 is online now Find More Posts by p901P901
Reply With Quote
Old Feb 17, 2012, 07:11 PM
Registered User
Joined Oct 2004
2,770 Posts
Nope, that's not what a gyro does. A gyro can only detect yaw rate, or yaw absolute orientation (but that's not the case with RC gyros) but not sideslip. A gyro does not know anything about the airflow. While it can be useful to dampen sudden yaw movements, it can't be used to limit sideslip or to stabilize an unstable model. It can only slow the departure enough that the pilot is able to correct it in time, but the plane won't ever fly hands off.
Brandano is offline Find More Posts by Brandano
Reply With Quote
Old Feb 17, 2012, 07:23 PM
Registered User
p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
1,243 Posts
Quote:
Originally Posted by Brandano View Post
Nope, that's not what a gyro does. A gyro can only detect yaw rate, or yaw absolute orientation (but that's not the case with RC gyros) but not sideslip. A gyro does not know anything about the airflow. While it can be useful to dampen sudden yaw movements, it can't be used to limit sideslip or to stabilize an unstable model. It can only slow the departure enough that the pilot is able to correct it in time, but the plane won't ever fly hands off.
So your talking about having the vane as a sensor for yaw control to prevent sidesliping? Then you could install a pitot tube in the front with these vanes to detect orientation. I used Pic microcontrollers before to convert linear pot singles to servo signals (PWM). This could be fed into a gyro to damp oscillations. Then into a mixer for controlling the yawing flight controls.
p901P901 is online now Find More Posts by p901P901
Last edited by p901P901; Feb 17, 2012 at 09:00 PM.
Reply With Quote
Old Feb 17, 2012, 07:28 PM
Registered User
Joined Oct 2004
2,770 Posts
Yep, that's what I meant. Essentially, if it is possible to arrange drag rudders to be operated by a single servo it should be possible to hack the servo so that it can automatically compensate for sideslip, and mix this compensation with the pilot's input. It would be possible to do this with two servos as well, but each would have to be hacked, and either both servos would need to be controlled by the same vane or two vanes would be needed. And each servo would have to operate so that only half the travel operates the drag rudder.
Brandano is offline Find More Posts by Brandano
Reply With Quote
Old Feb 17, 2012, 09:56 PM
Registered User
p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
1,243 Posts
Looks like the X-47B uses split flap drag rudders. On the top of the wing is part of a split flap system that is used also as roll control. There is also inboard flapervators. And looks like they all can interreact with each other
It may be easier to use inboard TE controls for pitch, split flap drag rudders for yaw and roll.
p901P901 is online now Find More Posts by p901P901
Last edited by p901P901; Feb 17, 2012 at 10:09 PM.
Reply With Quote
Old Feb 19, 2012, 03:46 AM
Registered User
frank40's Avatar
Denmark
Joined Sep 2005
866 Posts
Hey

If you look at this video you can se where the flaps is placed ans se the spoilers on top of the wing.

X-47B RC EDF 1:12 New model (0 min 48 sec)


Most of my EDF don't have rubber controls and flighs very well without it, so....
If you make the tailles model stable in all Axels will they still be necessarily in a tailless design.
frank40 is offline Find More Posts by frank40
Last edited by frank40; Feb 19, 2012 at 06:22 AM.
Reply With Quote
Old Feb 19, 2012, 05:39 AM
Registered User
frank40's Avatar
Denmark
Joined Sep 2005
866 Posts
I am i the process of making some chances in the design, please feel free to comment.

1: This will be a blended shape fuselage, the baseline in side view is a EH 1.5/9.0 airfoil, the LE will be modified to look like a normal nose tip with canopy.

2: The shape of the wing is altered to move the CG forward.

3: The inlet of the fan has been moved behind the CG.

4: Added some dihedral to the wing, for stability.
frank40 is offline Find More Posts by frank40
Reply With Quote
Old Feb 19, 2012, 12:59 PM
Registered User
p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
1,243 Posts
Quote:
Originally Posted by frank40 View Post
Hey

If you look at this video you can se where the flaps is placed ans se the spoilers on top of the wing.

http://www.youtube.com/watch?v=jgzbQ...eature=related

Most of my EDF don't have rubber controls and flighs very well without it, so....
If you make the tailles model stable in all Axels will they still be necessarily in a tailless design.
The X-47B EDF looked fine while it was flying. You could see a little sideslip while it was flying. He did not land straight so he could have had some cross wind.
I think having some drag in the wing tip will help yaw instability. The LX B2 has drag rudders and are deployed all the time.
B-2 Spirit! Stealth Bomber RC JET Flight Review in HD! Twin EDF RTF B-2! bananahobby.com! (10 min 1 sec)
They use this drag for yaw stability with the ability to change the defection with stick movements. So this is one possibility. You could also experiment with washout and fences. Things like body and airfoil geometry still leads to experimentation.
p901P901 is online now Find More Posts by p901P901
Last edited by p901P901; Feb 20, 2012 at 12:41 PM.
Reply With Quote
Old Feb 19, 2012, 05:43 PM
Registered User
p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
1,243 Posts
The X-47B lines are very similar to your design. Look at the control surfaces of the X-47B EDF to find out where to place yours. Spoilerons can be used for both roll and yaw. You will need to have the spoiler and outboard TE control surface partially deployed for yaw and have the spoiler move independently for roll. How much deployed will be according to the surface area of the surfaces.
Have you tried placing fixed drag rudders on your chucky?
p901P901 is online now Find More Posts by p901P901
Last edited by p901P901; Feb 19, 2012 at 07:11 PM.
Reply With Quote
Old Feb 19, 2012, 10:39 PM
Registered User
slebetman's Avatar
Malaysia, Selangor, Kajang
Joined Jun 2009
1,405 Posts
Quote:
Originally Posted by p901P901 View Post
To bad a computerized system like a quadcopter was not developed for an aircraft. Who knows what plane designs could have been developed with it..
Most quadcopter boards can be used to control planes as well. If you google around you'll find several fixed wing firmware for the well known and well tested KK boards. But for side slip control you'd need a board with accelerometers. The hardware is out there even commercially available. Just need someone to write the software.
slebetman is offline Find More Posts by slebetman
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Wanted vertical stabs for a twin jet Flying glass Aircraft - Electric - Airplanes (FS/W) 0 Jul 15, 2011 07:47 AM
Question Vertical Stabs - Single/middle vs twin center vs end winglets? Doubledog Flying Wings 2 Jun 07, 2011 12:57 PM
Discussion HET F-18 70mm need some help with the vertical stabs in the back sherlockshah Electric Ducted Fan Jet Talk 15 Nov 28, 2010 06:04 PM
Discussion What do you think of this one? Success with no vert. stabs and no drag rudders! all4smallrc Flying Wings 6 Oct 04, 2010 05:00 PM
Help with vertical stabs on Shike 10 conversion Kevin P Modeling Science 1 Nov 07, 2002 09:08 AM