New thread on TRIM

[TEShaw]

There has been some discussion on use of elevator trim in another recent hilarious thread.

Various assertions were made about WWII planes not having trim tabs, or, that an elevator in the full up position would not be affected by changing trim.

Now we have this from LYNX:

"Re: Gaming the game

From the Spitfire pilot note book....about .......TRIM.   (...)
Quote
AIRCRAFT CONTROLS
12. Trimming tabs.—The elevator trimming tabs are controlled by
a handwheel (30) on the left-hand side of the cockpit, the
indicator (24) being on the instrument panel. The rudder
trimming tab is controlled by a small hand-wheel (27) and is
not provided with an indicator. The aircraft tends to turn to
starboard when the handwheel is rotated clockwise."

Now, I ask you this in all honesty and curiosity. If an aircraft has trim tabs, and the elevator is in the full up position, would not raising the trim tabs change the elevator effectiveness?

regards, teshaw
 

[Wreked]

Posted this in the OTHER thread before I noticed this one: vaguely related.............

-------------------------***--------------------

A touch off base here but for those interested here's the flaps "wheel" control on a 109 - of interest was the fact that the elevator trim control wheel is right next to it so adjustments could be easily made to either at the same time without having to reach somewhere else. No hydraulics (I think) but straight manual power was the norm.

http://www.youtube.com/watch?v=qcMjhihuuX8


cheers eh!

[Anaxogoras]

The only time elevator trim helps get the nose up is when you're going too fast and are unable to deflect the elevator.

[SlapShot]

Now, I ask you this in all honesty and curiosity. If an aircraft has trim tabs, and the elevator is in the full up position, would not raising the trim tabs change the elevator effectiveness?

regards, teshaw
 

If the "trim tabs" were a separate controllable surface that is integrated on the elevator ... then I would think yes. To what degree would be another discussion.

I don't think that all WWII aircraft had "trim tabs" so "trimming" would actually be trimming the actual control surface itself ... so trimming an elevator to "full" and then pulling back on the stick and getting more pull ... I don't think would happen.

[CAP1]

There has been some discussion on use of elevator trim in another recent hilarious thread.

Various assertions were made about WWII planes not having trim tabs, or, that an elevator in the full up position would not be affected by changing trim.

Now we have this from LYNX:

"Re: Gaming the game

From the Spitfire pilot note book....about .......TRIM.   (...)
Quote
AIRCRAFT CONTROLS
12. Trimming tabs.—The elevator trimming tabs are controlled by
a handwheel (30) on the left-hand side of the cockpit, the
indicator (24) being on the instrument panel. The rudder
trimming tab is controlled by a small hand-wheel (27) and is
not provided with an indicator. The aircraft tends to turn to
starboard when the handwheel is rotated clockwise."

Now, I ask you this in all honesty and curiosity. If an aircraft has trim tabs, and the elevator is in the full up position, would not raising the trim tabs change the elevator effectiveness?

regards, teshaw
 

IF they were modeled as trim tabs, yes, i thnk so.

in here they're not though. if you do r/c, set your model on the ground, turn it on, but don't start it. adjust your trims. you'll notice the entire control surface moves.

 it's the same in here. watch your aielorons when you adjust that trim. or whichever trim you're adjusting. it's the entire surface moving. that's why when your elevator is full up, trimming it up will change nothing....there is no travel left.

[Karnak]

The only time elevator trim helps get the nose up is when you're going too fast and are unable to deflect the elevator.

Which in the case of the Spitfire means it wouldn't help.  Spitfires had, if anything, excessively light controls on the elevators allowing the pilot to get such effective deflection that Mk Vs were lost to overstress and controls rebalanced going forward.

[BaldEagl]

I found this:

When a trim tab is employed, it is moved into the slipstream opposite to the control surface's desired deflection. For example, in order to trim an elevator to hold the nose down, the elevator's trim tab will actually rise up into the slipstream. The increased pressure on top of the trim tab surface caused by raising it will then deflect the entire elevator slab down slightly, causing the tail to rise and the aircraft's nose to move down.


This would explain why they have no ability to improve turn performance and it also explains why they are so effective in overcoming control stiffness.

[Wreked]

Now, I ask you this in all honesty and curiosity. If an aircraft has trim tabs, and the elevator is in the full up position, would not raising the trim tabs change the elevator effectiveness?

What might be of interest is whether the graphics here actually indicate visually "true" trim adjustment or just something so you can see something has happened - my understanding of "trim tabs" were just that - small moveable things that were manipulated on the edges of the control surfaces they were for. (I'm one step away from saying "thinga-ma-bobbies"  LOL) You techies help me out please.

Would seem to me that; regardless of where the elevator is positioned; ANY trim adjustment will affect it - otherwise why have them if they didn't change anything. I'm not sure what this whole "trim" issure revolves around - WWII fighters had them and used them - end of story. (likely not  hehehe)

cheers eh!

[RufusLeaking]

Now, I ask you this in all honesty and curiosity. If an aircraft has trim tabs, and the elevator is in the full up position, would not raising the trim tabs change the elevator effectiveness?

A trim tab is a small area of the control surface that is adjustable in very small increments.  If I understand the non-movable horizontal stabilizer version of trim, the tab is adjusted to "fly" the control surface to a position that unloads the forces on the stick that are required to maintain level flight.  If this is the case, then the change in shape on the control surface caused by the deflection of the trim tab, which is a small percentage of the total control surface area, would cause a slight difference in effectiveness.  The force required to hold an out-of-trim position would fatigue the pilot, and probably would negate any tiny aerodynamic effect given by the trim tab itself.

[BaldEagl]

See my post above.  If they had any effect it would be to decrease control surface effectiveness in normal circumstances, not to increase it.

[RufusLeaking]

The only time elevator trim helps get the nose up is when you're going too fast and are unable to deflect the elevator.

I believe this is because the game itself automatically trims for a given airspeed.  In Real Life, piloting on manual controls requires almost constant trim changes when changing airspeeds, power settings, etc.  Elevator trim is by far the most adjusted of the three axis.

[TEShaw]

Rufus, Bald,

I didn't want to hear that.

So, in effect, you're prolly saying 'trim' in AH is an adjustment to the control surface...not the tab.

grrr,

Thanks.

regards, teshaw

[Yeager]

All these years I have been slaughtering you one-G pilots without using the trim keys.  The horror!....the horror.....

[RufusLeaking]

See my post above.  If they had any effect it would be to decrease control surface effectiveness in normal circumstances, not to increase it.

Roger that, BaldEagl.  We were posting simultaneously.  If one thinks it through to the logical extreme, for the tab to give an added aerodynamic boost, it would have to be trimmed in the opposite direction.  That is it would have to be trimmed to increase the force on the stick, requiring greater effort to pull back on the the stick.  There may be a point where the force on the stick might exceed the pilot's ability or the strength of the linkages between stick and elevator.

[TequilaChaser]

I believe this is because the game itself automatically trims for a given airspeed.

only if you have combat trim enabled

 In Real Life, piloting on manual controls requires almost constant trim changes when changing airspeeds, power settings, etc.  Elevator trim is by far the most adjusted of the three axis.

in real life, once the pilot got into fighting he was not as focused on being properly trimmed out, while they still would make QUICK minor adjustments, but not like they would make while they were in cruising / or patroling mode....


in Aces high, there is no Extra advantage to be gained trimming your elevators full up.....you only benefit from having to maintain the stick input ( less fatigue )....... it will infact not help you turn tighter........with that being stated, when flying against same type aircraft and while in a phonebooth/knife fight....trimming full up when slow could possibly help you over your opponent in the same plane, who might not be trimmed full up......this , in my view is the only time you would benefit from it......

also remember, if your Elevator is trimmed manually to full up, or you have Combat Trim enabled..you are fighting the Trim setting each time you try to go nose low and build speed back........ Combat Trim and Manual full up Elevator Trim can hurt you regaining speed

YMMV