PDA

View Full Version : Rudder Trim and "On the Ball"?



IronKestrel
01-31-2006, 12:30 PM
Typically, I need to trim the rudder a large amount prior to take-off.

However, once I'm in the air, what aeronautics do you use to determine if you are 'crabbing' in the air? After take-off I usually neutralise the rudder trim and then give it a few (~10) clicks to the right.

Is there a way to know that your airframe is running effeciently straight forward? Do you just use the feel of the stick to minimal pilot input?

Thanks for any tips.

IronKestrel
01-31-2006, 12:30 PM
Typically, I need to trim the rudder a large amount prior to take-off.

However, once I'm in the air, what aeronautics do you use to determine if you are 'crabbing' in the air? After take-off I usually neutralise the rudder trim and then give it a few (~10) clicks to the right.

Is there a way to know that your airframe is running effeciently straight forward? Do you just use the feel of the stick to minimal pilot input?

Thanks for any tips.

Bearcat99
01-31-2006, 12:46 PM
Center the ball with your trim.....

jugent
01-31-2006, 12:56 PM
You can trim the a/c with the rudder-pedals as well.
If the "ball" is centered the a/c speed without yaw. A metal-ball inside a gl*** tube, the inclinometer on some planes, other (Spit and Hurricane) got a pin that shows the same thing.

The a/c is inflicted by forces like torque, helix and unbalanced drag of different object on the frame which can be corrected by the rudder or trim.

The trim differs depending on speed or hight.
You can think of the yaw as if you are towing a boat with a wire and the wire is not connected perfectly on the front of the boat. You have to correct this by the rudder.
If you use the ailerons the "rudder" that is elevated on one of the wings gives more drag than the other "rudder" that is lowered, because the airflow is faster on the upside of the wing.
Gyro-effect of the engine causes yaw too.
This difference in drag causes the aircraft to yaw, and can be corrected by the rudder.

Skycat_2
01-31-2006, 01:20 PM
gl***
gla$$
glas$

I just want to see how this forum's filter works.

Breeze147
01-31-2006, 01:24 PM
Have some cl***.

horseback
01-31-2006, 02:01 PM
You ***ume too much.

I find that some of the Turn and Bank indicators are outrageously dishonest (most notably the Mustang, but the FW has some ugly moments too), or that certain types of aircraft have their 'ball' a quarter to half width to one side or another when flying straight and level.

Given that the virtual pilot lacks any inner ear or seat of the pants inputs, these at least should be absolutely reliable, regardless of what Oleg or anyone else thinks they 'should' have indicated for authenticity's sake.

About half the Soviet fighters' Turn & Bank indicators are hidden by the stick's 'spade' handle; I guess that is in order to balance out the comp***' being hidden behind/beneath the gunsight pad.

Your best method for determining that you are flying straight and level is to acclimate your self by flying the aircraft type in Wonder Woman view for a few hours, and keeping track of the vector circle. Having it centered is the best proof that you're flying smoothly, and once you can do that on a new aircraft fairly consistantly, flying it straight and level or in proper trim should come as second nature to you.

cheers

horseback

georgeo76
01-31-2006, 02:13 PM
you ***ume that I'm p***ive.

IronKestrel
01-31-2006, 02:50 PM
I could understand the advice if I knew which instrument indicated crabbing. The instrument with the 'pin'I ***umed indicated bank degree.

Generally I trim until the stick needs little input to keep straight, but the reason I am asking, is the event I need to maximise my speed and reduce drag. The input-alone method may not indicate how slippery the AC is trimmed.

Few aircraft actually have "the Ball..."

arjisme
01-31-2006, 03:43 PM
Question: if you trim rudder to stop roll, is that the same thing as centering the ball (if you don't have one/any http://forums.ubi.com/groupee_common/emoticons/icon_cool.gif)?

I ask because I just finished the BoB campaign and the Hurricane doesn't have an indictor. I just trimmed elevator to maintain level flight and rudder to stop rolling tendencies. Seemed to work pretty well.

horseback
01-31-2006, 04:11 PM
RAF fighters have a 'Turn & Slip" indicator, with an upper needle or arrow that points in the direction you are slipping or skidding. This is analogous to the 'ball' in the somewhat more common Turn & Bank indicator, also referred to as the Needle and Ball by some.

The lower arrow indicates the amount of bank or turn.

Likewise, the Needle indicates amout of bank or degree of turn, the ball indicates how far 'out of true' your nose is pointing.

Normal practice is to center the ball or slip arrow by adding rudder or rudder trim on the side they are indicating, or as some have said, "step on the ball."

cheers

horseback

arjisme
01-31-2006, 04:28 PM
Wow, how did I manage to miss that turn & slip indicator? I flew that entire campaign w/o using it. LOL!

Regardless, my question still stands: a s sume I was in an aircraft w/o a gauge to show the turn/slip. Would trimming the rudder as I described accomplish the same thing? I'll try a mission tonight in that Hurricane and see if it's true. I can verify with the appropriate gauge. :-)

edit: stupid filtering rules...

SweetMonkeyLuv
01-31-2006, 04:35 PM
The p51 is a holy terror to keep trimmed, and one often has the impression that the ball indicator is a little fubared.

Would be nice if there was a precisely correct slip/skid indication as an option in the speedbar, similar to the one in WorldWar2Online/Battleground Europe. Purists could leave it off for realism sake.

arjisme
01-31-2006, 04:55 PM
Yeah, I just started Nigel_Woodman's new P51 campaign and can see that it requires a lot of trimming. The new patch may help with some of this though. From the readme:

"Increased damping factor for the ball indicator.
Minor changes in reaction of the controls."

So, maybe less wobble and better trim feedback?

horseback
01-31-2006, 04:59 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ar****e:
Wow, how did I manage to miss that turn & slip indicator? I flew that entire campaign w/o using it. LOL!

Regardless, my question still stands: a s sume I was in an aircraft w/o a gauge to show the turn/slip. Would trimming the rudder as I described accomplish the same thing? I'll try a mission tonight in that Hurricane and see if it's true. I can verify with the appropriate gauge. :-)

edit: stupid filtering rules... </div></BLOCKQUOTE>I was fortunate enough to have a copy of the Hurricane MK II/IV Pilot's Notes. It includes a list of controls and indicators with a photo of the instrument panel properly numbered.

In the Spitfire at least, I found that the Slip indicator is dead on reliable, and was soon able to add just the right amount of rudder for smooth turns and banks, or rudder trim for straight and level flight with just an occasional glance at it in Wide View.

The tendency to roll in a given direction is usually due to engine torque; that's what the rudder trim is supposed to cancel out, to some degree.

SweetMonkey (mind if I call you by yur first name?), the Mustang's needle and ball are either

A) Just plain lies, or

B) Really, really sluggish. Instead of alcohol, the ball is sliding around in Jell-O.

cheers

horseback

Haigotron
01-31-2006, 05:27 PM
Is it normal, if I press F8 before take off and my rudder isnt fully centered? (w/o touching anything)

***ociation of the gl*** eye ***ociates...

blakduk
01-31-2006, 06:55 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ar****e:
Wow, how did I manage to miss that turn & slip indicator? I flew that entire campaign w/o using it. LOL!... </div></BLOCKQUOTE>

Dont worry about it. I've found, with the Hurricane at least, that if you use rudder to centre the needle it seems to SLOW you down. I haven't tried it on many other planes, i'm still enjoying the Battle over Britain campaign.

TX-EcoDragon
01-31-2006, 11:53 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ar****e:

. . .
Regardless, my question still stands: a s sume I was in an aircraft w/o a gauge to show the turn/slip. Would trimming the rudder as I described accomplish the same thing?. . . </div></BLOCKQUOTE>

Not really, if you trim the rudder at a given power and airspeed you will still experience torque induced roll. To counter this you need to either input opposite aileron or aileron trim. In order to trim the rudder until you don't experience the rolling you will have to trim in some additional rudder beyond the point at which the ball centers and though this may cancel out the roll due to yaw-roll coupling you will no longer be in coordinated flight, though this doesn't appear to be as much of a problem in the sim as in the real world.

msalama
02-01-2006, 01:43 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I just want to see how this forum's filter works. </div></BLOCKQUOTE>

It doesn't. HTH.