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using deflection on ailerons

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using deflection on ailerons

Old 12-01-2014, 08:55 AM
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Default using deflection on ailerons

in real terms im pretty much a beginner in flying traits etc and can anyone help me with trying to stop tip stalling with my max thrust mx2 by using deflection on the ailerons and how much
Old 12-01-2014, 03:19 PM
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All a tip stall is...is a stall where the wing tip stalls before the rest of the wing. Keep your airspeed up.
Old 12-01-2014, 03:33 PM
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If you had ailerons that were out towards the tip then adjusting them both up about 3 to 5 degrees provides some help.

However the model you have has ailerons that are nearly full span and the above would not work.

Moving the CofG forward a little can help a little.

Models of this general type are often designed so that they will snap roll, unfortunately this does mean that a tip stall is always possible.
Old 12-01-2014, 03:50 PM
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Did you mean adding "differential" instead of "deflection"?

Last edited by flyinwalenda; 12-03-2014 at 04:26 AM.
Old 12-01-2014, 04:02 PM
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Brian, adding differential will actually help avoid a tip stall. A tip stall occurs when the wing reaches it's max AOA and the tip stalls before the rest of the wing. On an aerobatic model with no washout having differential means that the downward aileron has less travel then the upward aileron and can balance out the stall somewhat. It's always the aileron with the downward movement that creates the stall. Flaperons is the last thing you would want to do, some guys run spoilerons to help with stalling at low speeds. this is bringing both ailerons up a few degrees. It is something that has been catching on more frequently with the pattern guys. As far as why the tip stalls are happening in the first place, my hunch is that the airplane is set up too nose heavy and has excessive elevator movement to compensate. A good test for the OP to try is to do a full elevator loop at 1/2 power. if the airplane snaps out of the loop it's a good indication that too much elevator throw is being used. It the airplane requires a lot of elevator to flair for a landing then it's too nose heavy.
Old 12-02-2014, 03:15 AM
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i did mean deflection ie the ailerons are set about 5mm up from normal level position to the rest of the wing forming a sortof washout to each wing
i will take on board what you say about differential many thanks
Old 12-02-2014, 03:25 AM
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yes many thanks for your help and advice as soon as weather permits i will try out these manouvers i will set up again after test runs to see how it loops as for the landing im pretty certain it never wants to flair out more like wants to keep flying then i suppose its flying too slow and a stall happens
Old 12-02-2014, 03:33 AM
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in that case would it be ok to glue some strips on the top of the outer ends of ailerons to form a sort of wash out say 100mm long
Old 12-02-2014, 05:16 AM
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If you plan to go the spoileron route I would not make it a permanent adjustment. I would set it up on a switch so that you could click to landing mode. You would not want to be flying that airplane around with the ailerons reflexed all the time. For that airplane I consider this a band aid. It's not fixing the actual problem. As I stated earlier, I think you are too nose heavy. You are most likely having to hold a fair amount of elevator at landing speeds. As the speed drops off your elevator becomes less effective so you give it more. At one point your elevator just gives up and that is your stall. Calculate out where your CG is, for that airplane it should be close to 30% of the average cord. An example is, go out halfway on the wing. If the cord there is 9" then the CG should be 3" from the wing leading edge at that point. I would be willing to bet you are farther forward then that.
Old 12-02-2014, 05:24 AM
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JCW The various methods already covered by the fellows to soften the stall departure is quite accurate and specifically reflexing the ailerons up just a few degrees up above the intrail position on the wing will help it is nothing more than doing the same thing as using wash out on the trailing edge and it will work even with strip type ailerons as well as bn doors, without a doubt it is the easiest to experiment with if experiencing and unpleasant stall departure after confirmation you simply do not have to much elevator through as outlined above by Jester, I think.

Now while I would not start attaching appendages on your aileron a better approach and one used often in the full scale world is to attach a simple stick on the wing root leading edge. Best example I can think of is all versions of the Mooney aircraft us a foot long triangular strip at the very font of the airfoil profile. Its purpose is to trip a stall at the wing root before the wing tip region. And yes I have used this method successfully on a few model aircraft it does work. This method accomplishes exactly the same thing a Washing out a wing tip or reflexing both ailerons up from the in trail position in neutral.

John
Old 12-02-2014, 07:12 AM
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Originally Posted by JohnBuckner View Post
JCW The various methods already covered by the fellows to soften the stall departure is quite accurate and specifically reflexing the ailerons up just a few degrees up above the intrail position on the wing will help it is nothing more than doing the same thing as using wash out on the trailing edge and it will work even with strip type ailerons as well as bn doors, without a doubt it is the easiest to experiment with if experiencing and unpleasant stall departure after confirmation you simply do not have to much elevator through as outlined above by Jester, I think.

Now while I would not start attaching appendages on your aileron a better approach and one used often in the full scale world is to attach a simple stick on the wing root leading edge. Best example I can think of is all versions of the Mooney aircraft us a foot long triangular strip at the very font of the airfoil profile. Its purpose is to trip a stall at the wing root before the wing tip region. And yes I have used this method successfully on a few model aircraft it does work. This method accomplishes exactly the same thing a Washing out a wing tip or reflexing both ailerons up from the in trail position in neutral.

John
+1 very good advice here.
Old 12-02-2014, 07:29 AM
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Agreed but with one exception. The MX is an aerobatic model. Reflexing the ailerons will have an adverse effect while the model is being flown inverted. The stall strips on the inboard wing will raise the stall speed of the airplane overall. IMO the OP really should not resort to adding such fixes to an airplane that is simply not trimmed correctly ( CG ). Personally I would like the OP to come back and let us know what % the CG is currently. I'm 99% sure this is the actual issue.
Old 12-02-2014, 12:31 PM
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Thanks john for your imput into my problem is this also called a toblerone as ano flyer suggested
Old 12-02-2014, 12:39 PM
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JCW, where is your CG position in relationship to what is called out in the manual?
Old 12-02-2014, 12:42 PM
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THANKS VERY MUCH TO YOU ALL FOR HELP AND IDEAS MY CURRENT C ofG AS YOU HAVE SAID IE AT ROOT CORD 12" HALF W/S 24 SO AT 12" THE CORD IS 9" AS YOU HAVE SAID MY C ofG BALANCED AT THAT POINT BUT 31/4 FROM LEADING EDGE
Old 12-02-2014, 12:44 PM
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Im now measuring it with battery in situ balancing level on 2 fingers exactly as the book 100 mm
Old 12-02-2014, 12:52 PM
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Most manufacturers will give a good conservative CG. you could place the battery in a little aft and safely move the CG back 1/8" and see if it improves. How much elevator deflection do you have and does the airplane require up trim?
Old 12-02-2014, 01:08 PM
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Originally Posted by [email protected] View Post
in that case would it be ok to glue some strips on the top of the outer ends of ailerons to form a sort of wash out say 100mm long
Elevator is the control that is going to cause you to snap. If you are having a problem with snapping, then reduce your elevator input or add a bunch of exponential.
Old 12-02-2014, 01:32 PM
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My main prob is that on finals im finding the model just wants to fly on then as my airspeed falls its wanting to tip stall i fly and land on a pretty small patch and iam trying to stop overshooting as i the models suffer with u/c damage in the long grass or is there a better solution for a clean landing
Old 12-02-2014, 01:51 PM
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Originally Posted by speedracerntrixie View Post
Most manufacturers will give a good conservative CG. you could place the battery in a little aft and safely move the CG back 1/8" and see if it improves. How much elevator deflection do you have and does the airplane require up trim?
If you can't move the bat back try the stick on weights 1/2 oz at a time, I would but them inside your bird/

Cheers bob T
Old 12-02-2014, 02:00 PM
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OK I WILL TRY THAT MOVING CofG BACK A LITTLE AS SPEEDRACERTRIXIE ORGINALLY SUGGESTED CHEERS ALL
Old 12-02-2014, 02:06 PM
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Originally Posted by [email protected] View Post
My main prob is that on finals im finding the model just wants to fly on then as my airspeed falls its wanting to tip stall i fly and land on a pretty small patch and iam trying to stop overshooting as i the models suffer with u/c damage in the long grass or is there a better solution for a clean landing
for the most part, an airplane that seems to want to stretch its final has a forward CG location. JCW are you holding 1/2 or more back stick on final and how much elevator travel do you have? Moving the CG to the back of the range and decreasing the amount of elevator travel will not only stop the tip stall, it will also lower the landing speed. I realize this is opposite from what we were taught long ago but airplanes have much lower wing loadings these days and tolerate aft CG setting much better. I apologize for the lengthy video but at 15:00 in it shows me flying my Extra in a very confined area, it really was too small for the airplane but you will notice how slowly I was able to get the airplane on the second landing attempt. I run the CG at the back of the range and fly with only 12 degrees of elevator.www.youtube.com/watch?v=Wj9VFMz0uI8
Old 12-03-2014, 02:28 AM
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WOW some fling site and what a lovely blue sky i take it you were flying the all red Extra and very well i might add im way down the list in ability to get near to flying like that but yes point taken and with my mx2 i will do as you suggest moving the c of g back a little at a time untill i achieve what you seem to be doing ie coming in tail low many thanks and best regards John
Old 12-03-2014, 05:11 AM
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Thanks John. I refer to myself as a " Lifer " having grown up around R/C and have been flying for almost 40 years. As you slowly work the CG back don't forget to reduce elevator travel as well. I would suggest you use no more then 15 degrees. If your radio has the expo feature I suggest setting that to about 20%-25% as well. Some radios will allow you to set both positive and negative expo so be careful on that. What expo does is reduce the amount of throw around center. Something you may already know about but just in case.
Old 12-03-2014, 05:47 AM
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Originally Posted by speedracerntrixie View Post
. At one point your elevator just gives up and that is your stall. .
Are you sure about that?

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