Flatten the wing for ailerons?

[Dave B.]

I was just at a hobby shop and we started talking about adding ailerons to the SC wing. I am nowhere near the skill level to worry about this yet, but he said some things that have me wondering.

He insisted that is was necessary to take the dihedral out of the wing, to flatten it completely in order for the ailerons to actually do anything good.

Is that true? And if so, why?

[iflyforfun]

Lets start with dihedral. Think of the aircraft in level flight, the wings are bent up(dihedral). The wing tips are higher than the wing root(dihedral). So think about how this affects the aircraft in flight. Dihedral affects the aircrafts roll stability. When an aircraft becomes upset in flight and a wing drops many thing start to happen and It would take me 5 hours to write them all down so I'm gonna give you the short version!!!! The wing that drops starts to create MORE lift than the wing that is raised. Thats all you need to know unless you want to study aerodynamics. If you do want more info then you need to study thing like dihedral effect, stable spiral mode, uncompensated lift component and non-zero sideslip. 

So the simple answer for the "dihedral" question is "" the wing thats lower wants to go back to a level state because it is creating more lift than the high wing is". 

Lets talk about Ailerons. All they do is deflect the onrushing air in another direction. Pretty simple if you remember that for every action there is a reaction. Air hitting a raised aileron gets deflected upwards and pushes the wing downwards. Same thing for a downward aileron, it wants to push the wing upwards.

So lets add these 2 forces together. You can see whats happening or what would happen if you apply a left turn on a wing WITH DIHEDRAL, the left aileron goes up the air hitting that upward raised aileron pushes the wing down and as it goes down the dihedral fights against this force and wants to raise the wing back to level.

Not the most effective way to fly. !!!!!!!!

Now on to what your hobby shop told you!!!!  Let me try and take the middle ground!!! Will it fly.. Yes,yes,yes,yes and dam yes. It will fly just fine. As a new rc pilot you will not even notice anything bad!!!!  There is some bad effects that this will have on your learning curve but the aircraft does not give a crap about your learning curve. For example flying with dihedral and ailerons will cause you to have to keep in a certain amount of aileron deflection durning your turn. When you release the stick the aircraft will come back to level flight all by itself. You may say " well whats bad about that " in a normal aileron aircraft without dihedral you normally give it a touch of aileron to start a turn and then release the stick. The aircraft will continue to turn until you add opposite aileron to stop the turn.

Ok, so now you got the basics!!!!

Will it work, YES, WITHOUT A PROBLEM!!!!!!!
Is it the correct way to lean NO.

Adding ailerons to the Cub is a very cheap alternative to buying a new aileron trainer and can be done very easily. I flew mine with dihedral and ailerons for months because I was to lazy to flatten the wing. Then when I finally got around to flatting the wing I did it the extra easy cheap way by just running strips of clear packing tape on the underside of the wing from tip to tip. Works perfectly.

Ifly

[Dave B.]

Thank you for all that info! I do not intend to go the aileron route yet, I have too much yet to learn. But I do plan to put my own ailerons in when the time comes, the info you provided is very helpful!

[bo54]

That's a pretty good, quick explanation Ifly.

[pianodood]

ifly, that is an exceptional explanation.

I'm going to read it again, simply because I enjoyed it.