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Bank and Yank

#1
Hi Everyone,
I have seen this in many places in the forums and would like a clarification on exactly what you are referring to. My guess is that it involves the use of ailerons and elevator to do a turn without using rudder. I was playing with Clearview this afternoon and noticed that when I banked I had to use a little up elevator to maintain height while it turned. As I was using the keyboard I didn't have time to involve the rudder and turns without it seemed to flow easily enough. Is this the same in the real world? I see when people fly 3 channel they recommend putting the rudder where ailerons normally go and I assume that when they go 4 channel and everything goes in the right spot that the muscle memory doesn't cause too many problems and the ailerons initate the turns as easily as the rudder. Is this right or is it completely different?
Mac
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#2
Hi Everyone,
I have seen this in many places in the forums and would like a clarification on exactly what you are referring to. My guess is that it involves the use of ailerons and elevator to do a turn without using rudder. I was playing with Clearview this afternoon and noticed that when I banked I had to use a little up elevator to maintain height while it turned. As I was using the keyboard I didn't have time to involve the rudder and turns without it seemed to flow easily enough. Is this the same in the real world? I see when people fly 3 channel they recommend putting the rudder where ailerons normally go and I assume that when they go 4 channel and everything goes in the right spot that the muscle memory doesn't cause too many problems and the ailerons initate the turns as easily as the rudder. Is this right or is it completely different?
Mac
When you bank the wings the lift vector is no longer only to oppose gravity and so the effective lift against gravity declines. By adding a little up elevator you increase the angle of incidence of the wing and therefore increase the wing lift. Done exactly right the extra lift due to the elevator input will increase the lift Vs Gravity back to equality and the plane will accomplish its turn without losing any height.

Mind you there are other forces in play including the balance point but generally height can be maintained through a banked turn.

The use of the Aileron Rx slot for the rudder on 3 channel birds is simply so that you do not get confused when going from 3 channel to 4 channel installations. When teaching others to fly, (yes I do instruct locally), I teach the newbies that the aileron channel is the PRIMARY turn channel and that the other channel, (the rudder(, is the secondary turn channel and is also used for balancing turns.

Rudder only turns are totally different in their mechanisms and a rudder ONLY turn can be near impossible to accomplish with a bird without any other stability mechanism such a dihedral or pendulum stability. A severe application of aileron with result in a roll whereas a severe input of rudder will result in a rapid, (Tail sliding), turn, roll and a dive. The rudder roll and dive can be better understood if you do a little research on the "Dutch Roll" effect.

Bank and yank is simple and effective especially on high speed aircraft as in racers and also in combat!

Have fun!
 

Kananga

Active member
#3
Yes, you use ailerons to turn the plane on it's side (bank) and the use elevator to bring it round in a circle (yank).
With increased elevator over the rudder size the yank part is very effective.
 
#4
[QUOTE="Hai-Lee, post: 475490, member: 26654"........ SNIP............. By adding a little up elevator you increase the angle of incidence of the wing and therefore increase the wing lift. ......... SNIP.............[/QUOTE]

A VERY good reply, but I'll pick one little nit. What you increase as you add up elevator is the angle of attack, not the angle of incidence. The angle of incidence is fixed when you attach the wing to the fuselage. On simple trainers it is often set at a couple of degrees of positive incidence. For 3D flyers intended to fly inverted as well as they do right-side-up, the angle of incidence is most often zero. Typically the wing incidence doesn't change with one notable exception, the F-8 Crusader.

I'm particularly sensitive to the proper use of the word "incidence" because I logged 153 combat missions in the LTV F-8 Crusader, an interesting aircraft with a variable incidence wing.

Google it.

We raised the wing for take-off and landing which did a couple of good things. It allowed the fuselage to remain at a low angle so we could see over the nose which was nice for carrier landings. It also let us fly slowly with the fuselage not nearly as cocked up as normal aircraft and that allowed LTV to build unusually short, strong, and light main landing gear struts because the danger of scraping the tail pipe on landing was greatly reduced. As far as I know, the F-8 was the only aircraft produced in any numbers with a variable incidence wing.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#5
I am aware of the Crusader and its rather unique wing incidence altering mechanism. We needed to be able to recognise the aircraft of friends and Foes during my period of military service here!

As for the Angle of Attack Vs Angle of Incidence both are correct. It is a matter of where you were educated.

Just a quote/clip from the Wikipedia page on Angle of Attack - "Some British authors have used the term angle of incidence instead of angle of attack.[5] However, this can lead to confusion with the term riggers' angle of incidence meaning the angle between the chord of an airfoil and some fixed datum in the airplane.[6]".

Both terms are in use and are equally valid!

Have fun!
 
#6
......... snip.......... "Some British authors have used the term angle of incidence instead of angle of attack.[5] ........ snip.......!
We fought two wars to break away from the British and we'll fight another one if we have to so that we can speak "Mercan" rather than the Kings English. When I tune my car, I'll say "rough idle", not "lumpy tick-over". And I will never smoke a fag. I like pecan pie for desert, not Spotted Dick, thank you very much.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#7
There we have it! You are free to speak "Mercan" or any other language you wish to and in a similar way I should be free to speak English, (or Aussie), if I wish to!

In a shrinking world it is better to try to understand what our neighbours are saying rather than to close our minds to the views and ideas of others. In recent history our countries have fought side by side in 4 wars, (not counting IRAQ), The rough idle is also used here along with poor idle. Lumpy idle is normally a reference to the massive cam lobe overlap and its effect at idle. If I had a spotted dick I would see a doctor!

Here we have both UK and USA versions of English readily intermixed and we use both in regular conversations without demanding specific terminology! Here we deal with Engineers, (and others), from many countries with different usages of poor English, it is just a matter of fact in a widely diverse world.

I did not say that the Angle of Attack was an invalid term but I did say that the Angle of Incidence is an equally valid term in engineering terms. As FT has a worldwide audience is it too much to ask for tolerance and consideration of others, their cultures, their language, and their views?

Please remember that this is not Facebook!

Have fun!