Slipping in turns

[niklas]

Hi

A german shooting fible mentions that you have to use ailerons and rudder to start a turn, else the machine will slip a lot (ailerons only).

My question: Why does the machine slip through a turn when you start the turn with an aileron roll only?

niklas

[illo]

I know only little about this but.

Some planes drop nose easier than others when aerlon rolling. Applying opposite rudder to turn would keep nose slightly up and counter the slide. I really don't know what was the case with 109 but in 190 there was no tendency to drop nose while rolling. I think applying rudder depends much on speed and G-forces that will be pulled in turn. In example if you only roll to turn but continue forward without applying elevator/rudder you will slide down and propably nose will start dropping. If you pull some Gs you will actually get some lift and plane begins to climb without much if any slip.

Well...i leave rest for pros.

[Khavren]

When an aircraft turns...there are two (well 3 if you count a coordinated turn) things that can  happen...and bear in mind thise explanation is very basic.  Other factors can contribute, but I'll leave these factors out to make it simple.

When an aircraft banks into a roll, lift decreases causing (due to both the airfoil of the control surfaces changing attitude, as well as drag from an increase in surface area exposure from the empenage) the aircraft to drop or lose altitude.  The airframe's velocity is no longer in line nose to tail (forward motion basically) and visually the airframe is dropping towards it's lower wing.  This is called slipping.  Jes like if you were to lose footing on an inclined plane (ie...on the side of a hill) you'd slip.

There is also what is called a skid.  If you turn with rudder only, keeping aileron's level, the aircraft's attitude would change, but inertia will try to maintain the aircrafts velocity in the same direction.  Basically resulting in the airframe sliding, or Skidding into the direction before the turn.

You can monitor slipping and skidding by looking at that li'l curved tube with a ball in it on your instrument panel.  If the ball moves towards the outside of your turn, your slipping.  If it moves inside of your turn you're skidding.  Keeping it centered during a turn ensures minimal amount of energy loss during a turn.


If this explanation isn't very coherent...that's because I'm squinting jes to read what I'm typin...a bit tired I am....48hours no sleep ugh.

[Naudet]

I think its because the fuselage of the plane will at the start of a turn not be inline with the movemet of the plane.

Just imagine the forces applied. If you fly straight, ur lift vector goes up, the plane will just move forward and no force to left or right is active.

Now u roll and some of the liftvectors force is redirected into the left/right.
This greats a turn movement. But because you just rolled the fuselage (longitutidial axis) is still headed in the old direction. This greats a certain angle off to the new movement heading. And so the plan is sliping throught the airstream.

But if you give rudder, the fuselage will yaw into the new movement an so the slip will not accured.

The sliping will also be solved when the plane keeps the turn, cause the airstream will force the longitutidial axis into the turn, until there is no more sideforce working on the fusalge and vertikal stab.


Btw were can i get this GE shooting fible?

[niklas]

my problem is: I can imagine very well that the nose drops wenn rolled into a turn, but when i apply rudder in the same direction, doesnīt this increase the tendency to drop the nose?

Using right rudder in a right turn must counter a left slip or skid, logically, but i donīt understand how an simple aileron roll to the right produces such a slip or skid.

niklas

[Seeker]

The outside wing in a turn has to travel a greater distance, which means it's going faster, which means it produces more drag.

This results in a pull on the fuesalage towards the out side of the turn, known as adverse yaw. The rudder is used to correct this.

Have you ever been in a glider? One of the most important instruments on a glider is a peice of brightly coloured thread glued to the out side of the canopy right in front of your nose.

If you're flying "clean", the thread will always be pointing straight up, as you've correctly coordinated the controls to fly straight into the relative wind.

If you're not, if you've either not used enough rudder to account for the adverse yaw, or you're using too much rudder and holding the bank angle by using the aerlirons, the cotton willl be at an angle; it will point to the outside of a turn in a slip (not enough rudder) and to the inside in a skid (too much).

All this ignores two other large forces on our AH planes -  the gyroscope effect of the prop, and prop wash it's self; both of which do funny things to an aircraft trying to change it's atitude from straight and level flight, and produce forces which need to be countered with the rudder.

[funkedup]

Adverse Yaw

[hitech]

What you are refering to i.e. Yaw when starting a roll is caused by the drag difference on the 2 wings.

If you start a roll to the left, the left wing has less lift, hence less drag, the right wing has more lift hence more drag, the difference in lift is what cuases the plane to start rolling left.
The difference in drag is what causes the plane to yaw to the right.

[Duedel]

I suggest to read the article about rudder from Andy Bush at SimHQ. It's really great!

My (dumb) question:
Is this modelled in AH?

[Tac]

German planes were bulky, BUTT ugly and looked like a brick with anal bleeding problems.

Thats why the streamlined, beautiful, allied rides dont have that problem.

What a dumb question.

NEXT!

[Naudet]

Hehe Tac, as far as i know Eric Brown praised the FW190 for its exellent handling, it could be flown without ever touching the rudder for any normal maneuver.

[GRUNHERZ]

Tac bad. Tac mean.

[niklas]

thx guys, itīs clear now.

i heard that the FW190 had a "differential" ailleron control to overcome a "negative turning moment" at the beginning of a turn, what seems to be the effect hitech described. Does anyone know how it works?

niklas

[SageFIN]

Originally posted by niklas
thx guys, itīs clear now.

i heard that the FW190 had a "differential" ailleron control to overcome a "negative turning moment" at the beginning of a turn, what seems to be the effect hitech described. Does anyone know how it works?

niklas

A shot in the dark but here goes:
From your description, I would guess that it means that in the roll, the aileron from the wing that has more drag isn't extended as far as the aileron on the other wing. Ie. there's some regulator that keeps the aileron from extending as far as the position of the controls would imply. That would probably result in reduced roll rate though so blah.