Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: TEShaw on July 27, 2009, 12:01:15 PM
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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
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Posted this in the OTHER thread before I noticed this one: vaguely related.............
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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 (http://www.youtube.com/watch?v=qcMjhihuuX8)
cheers eh!
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The only time elevator trim helps get the nose up is when you're going too fast and are unable to deflect the elevator.
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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.
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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.
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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.
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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.
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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!
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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.
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See my post above. If they had any effect it would be to decrease control surface effectiveness in normal circumstances, not to increase it.
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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.
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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
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All these years I have been slaughtering you one-G pilots without using the trim keys. The horror!....the horror.....
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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.
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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
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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
Not sure if my understanding is correct but I believe all you would get is lighter feel on the stick. The elevator cannot go any further than the manufacturers full stop.
Folk also have to realise that once off combat trim you have to keep trimming by hand. If your con dives low you'll quickly have to trim down or level or put combat trim on. Some folk use a notch of flaps or two and trim nose low to compensate for the bouncy nose up feel. All to fiddly in a multi con situation for my liking. Press this press that watch this watch that when all the time trying to pull a lead or deflection shot. But hey...different strokes for different folks.
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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.
No, I think that's backwards.
Think about a compressed dive. The airstream is providing greater force then the pilot can overcome by pulling back on the stick, thus the elevators are locked. When the pilot trims up the trim tab is deflected down into the airstream providing an upward force on the elevator which is transferred to the stick thereby assisting the pilot in pulling it back.
The pilot can trim in this instance because the trim tab is relatively small compared to the elevator itself so forcing it into the airstream is relatively that much easier.
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No, I think that's backwards.
Think about a compressed dive. The airstream is providing greater force then the pilot can overcome by pulling back on the stick, thus the elevators are locked. When the pilot trims up the trim tab is deflected down into the airstream providing an upward force on the elevator which is transferred to the stick thereby assisting the pilot in pulling it back.
You are right.
What I am saying about the logical extreme is that to pull the nose up at the maximum rate is to deflect the trailing edge of the elevator up. The little trim tab is on the trailing edge of the elevator, and, when trimmed in the full nose down direction (opposite), the trailing edge of the trim tab would also be deflected up and act as a much smaller elevator on the actual elevator.
The mental and physical efforts would make this plain silly in Real Life.
Regarding changing trim in combat, I doubt it was a widespread practice. While training in the USAF, I had to demonstrate proficiency in certain maneuvers, such as the split S, Immelman, full loops, etc. One trimmed to the point of entry and then just went through the maneuver with what one had. The 'feel' of the stick was often a good clue to one's flight situation.
In AH2, is there a feedback option? I do not have a force feedback on my stick. So, a lot of this discussion is probably not useful in game.
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Thanx for the explanaitions folks - This is all starting to make sense (note I said starting) - so help me out here:
When in a dive sometimes I "run out" of stick sometimes and can not keep the nose down - hammering on the trim "I" key will bring it back - what is this all about? why is it happening? and can it be avoided all together??
cheers eh!
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Wreked,
Don't hijack this thread with your 'lift' issues.
regards, teshaw
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Thanx for the explanaitions folks - This is all starting to make sense (note I said starting) - so help me out here:
When in a dive sometimes I "run out" of stick sometimes and can not keep the nose down - hammering on the trim "I" key will bring it back - what is this all about? why is it happening? and can it be avoided all together??
cheers eh!
That happens because you are trimmed for level flight. In level flight there's always a slight nose-up elevator deflection. As the airstream forces become greater in your dive the nose up elevator deflection becomes more pronounced, thus you need to trim down to release pressure on the stick. Some planes are affected by this more than others.
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Thanx for the explanaitions folks - This is all starting to make sense (note I said starting) - so help me out here:
When in a dive sometimes I "run out" of stick sometimes and can not keep the nose down - hammering on the trim "I" key will bring it back - what is this all about? why is it happening? and can it be avoided all together??
cheers eh!
i've done that in lancs......dive, full forward stick......fll down trim changed nothing...the nose still came up.
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Wreked,
Don't hijack this thread with your 'lift' issues.
regards, teshaw
Thanx shaw - I do indeed appreciate your polite words of help - however by "lift" if you are referring to gravity then I'm clueless - isn't that something best overcome with a wand and 2 pinches of newt navel lint??
cheers eh!
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When in a dive sometimes I "run out" of stick sometimes and can not keep the nose down - hammering on the trim "I" key will bring it back - what is this all about? why is it happening? and can it be avoided all together??
Lift is a function of airspeed. For a given airfoil (chord, camber, etc.), as airspeed increases, lift increases. At least until shockwaves start forming, at which time all bets are off, along with some plane parts.
It looks like in the modeling, the increased lift exceeds the elevator authority to keep the nose down. To keep beating a dead horse, trim won't give any more deflection on the elevator.
Personally, I have never encountered this in real life. Then again, there are many actions in AH2 that I haven't done in the real world.
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What is the reason for trimming a plane? Is it just a necessary evil of turning Combat trim off..... Is it not true that all 38 jocks trim their planes? and fly with combat trim off.
<S>
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Because, simply stated, an aircraft will only be stable in a specific configuration at a single speed and/or center of gravity. Any change in speed and/or center of gravity will make the plane want to climb, descend, roll, yaw, etc. Trim allows the pilot to decrease his workload by making fine-tuned adjustments to control surfaces that will "balance" (for lack of a better term) the controls for the specific configuration he's in. Ultimately, a perfectly trimmed aircraft will fly "hands-off". For maneuvering flight, adjusting trim makes certain control inputs easier--i.e. they require less force from the pilot, reducing the effort required, and reducing fatigue over the long term.
Since speed is a function of pitch, the elevator trim is often the most used trim control in the aircraft, since the most common configuration change in an aircraft is speed. Even the most simple planes will typically have pitch trim. Some more sophisticated aircraft have pitch, aileron, and rudder trim. Some WWII aircraft had all three, and some did not. The Bf-109 series, for example, did not have adjustable rudder trim tabs. Aileron and rudder trim are typically only seen on higher performance aircraft.
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Is it not true that all 38 jocks trim their planes? and fly with combat trim off.
<S>
I'm no 38 jock but the answer is "No".
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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.
if you'll notice, the ailerons on the f4u's in game have servo tabs as described..
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if you'll notice, the ailerons on the f4u's in game have servo tabs as described..
They're modeled, which gives me hope that someday we'll actually have the aerodynamic model reflect trim tabs versus the partially deflected control surfaces. Until then, we'll just have to make do...
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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.
I was about to post that. I've never been a believer of trim helping the airplane do anything better (turning, rolling, etc).
The only reason trim exists is to relieve the control pressures felt during flight at a given airspeed/configuration.
The Super Cub, and some other airplanes use a jackscrew in the tail to adjust the pitch of the horizontal stabilizer, basically changing the angle of attack of the horizontal stabilizer to increase/reduce lift and in turn changing the stick pressures felt.
Also, in Aces High, there isn't an airplane in the game that I don't have the elevator authority to pull it into a stall at any speed. So adding nose up elevator trim would be useless, because you couldn't use that extra elevator to pull the nose around any faster after you've exceeded the wings critical angle of attack.
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Also, in Aces High, there isn't an airplane in the game that I don't have the elevator authority to pull it into a stall at any speed. So adding nose up elevator trim would be useless, because you couldn't use that extra elevator to pull the nose around any faster after you've exceeded the wings critical angle of attack.
Try the Mossie.
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For a simple visual aid for those who are not sure if adjusting trim help turn tighter. ( it does not )
get in a 38 pu the head position all the way back and and watch the yoke. hope thats the right term for the sitck in a 38.
pull back on the joystick all the way it will only move so far. now adjust trim all the way up and pull back it still stops at the same place.
you can see that the trim just make fine adjustments.
I would ask guys in the DA how are you getting around so fast. and they would tell me to use the trim key. :x
OH ya everyone knows that Alt f4 will make you turn tighter and put you in god mode. :devil
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I think its true that in r/l trim is used to make things easier for the pilot so that time spent at the stick isnt such a stress. In AH though it seems to me that trim is all about speed and not about pilot load but thats because in AH 'neutral' is always in the middle and the load on the pilot never changes. HT did a very good job on taking things as far as he could with the controls and his ideas about trim add a whole new level to combat. I have heard the arguments about trims becoming a new control component and I just dont buy it. Its not a 'secret victory button' or whatever its just trim but it is important to learn and thats why we have the training arena.
In WWII some airplanes had no trim controls but in AH everyone has trim and there isnt anything more fair than that. Maybe not realistic but it is fair.
The only thing you need to learn about trims really is how to change it. Set your controls up so you can trim and NEVER use combat trim. Learn how to trim to go fast and then learn how to trim for combat and remember that as the fight slows down you will always have to re-trim. Dont forget to retrim for speed after you are finished fighting. Also learn how to use the speed command (.speed 175 or .speed 225 or what have you) and when to use it!
I could write 25 pages on this but since I just did that you will have to wait until its ready. :D
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I think its true that in r/l trim is used to make things easier for the pilot so that time spent at the stick isnt such a stress. In AH though it seems to me that trim is all about speed and not about pilot load but thats because in AH 'neutral' is always in the middle and the load on the pilot never changes. HT did a very good job on taking things as far as he could with the controls and his ideas about trim add a whole new level to combat. I have heard the arguments about trims becoming a new control component and I just dont buy it. Its not a 'secret victory button' or whatever its just trim but it is important to learn and thats why we have the training arena.
In WWII some airplanes had no trim controls but in AH everyone has trim and there isnt anything more fair than that. Maybe not realistic but it is fair.
The only thing you need to learn about trims really is how to change it. Set your controls up so you can trim and NEVER use combat trim. Learn how to trim to go fast and then learn how to trim for combat and remember that as the fight slows down you will always have to re-trim. Dont forget to retrim for speed after you are finished fighting. Also learn how to use the speed command (.speed 175 or .speed 225 or what have you) and when to use it!
I could write 25 pages on this but since I just did that you will have to wait until its ready. :D
it does change pilot load in here.
take a spit, or zeek.....or pony........turn off compat trim, and use manual take off. leave the aircraft trimmed as it was for takeoff.
accelerate to your cruise speed. you'll be holding a lot of rudder, and stick offset. adjust the trims so you[re flying hands off now. now pull the throttle back to 1/2. you'll be changing your stick and rudder to compensate.
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You know how I learned about trim in the game?
The first time I took up a plane in AH I used auto take-off, got into the air, pointed the plane in the direction I wanted to go and let go of the stick expecting it to go into auto pilot just like it had in AW. Pretty soon I was rolling off to one side, my ascent rate had changed and I started trimminig. I was thinking "this is going to take a lot more effort".
I flew like that for the first few days before I figured out the auto pilot modes. :)
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I thought that when you entered compression that it was caused by the disruption of the airflow over the control surfaces.(shock wave) If that is the case then trim tabs would not work because the airflow over them would cause them to not work properly with the disturbed air.
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I thought that when you entered compression that it was caused by the disruption of the airflow over the control surfaces.(shock wave) If that is the case then trim tabs would not work because the airflow over them would cause them to not work properly with the disturbed air.
THEY don't. getting into thicker air does.
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You know how I learned about trim in the game?
The first time I took up a plane in AH I used auto take-off, got into the air, pointed the plane in the direction I wanted to go and let go of the stick expecting it to go into auto pilot just like it had in AW. Pretty soon I was rolling off to one side, my ascent rate had changed and I started trimminig. I was thinking "this is going to take a lot more effort".
I flew like that for the first few days before I figured out the auto pilot modes. :)
HT's Warbirds had the exact same trim controls as AH, except there was no 'combat trim.' There was no auto-takeoff either. Otherwise everything was the same, e.g. shift-x, cntrl-x, etc.
Smart pilots would trim their aircraft for their anticipated future speed before they entered a fight.
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HT's Warbirds had the exact same trim controls as AH, except there was no 'combat trim.' There was no auto-takeoff either. Otherwise everything was the same, e.g. shift-x, cntrl-x, etc.
Smart pilots would trim their aircraft for their anticipated future speed before they entered a fight.
I trim mine for cruise flight. when i see a furball, i re-adjust it for slow flight. it lets me use a little less stick input.
the only thing i run into, is if the con i'm fighting, extends, then i have to retrim in order to follow him.
i have noticed that if i fight slow with combat trim on, it almost seems as if i'm fighting AGAINST the trim at that point.
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The only thing you need to learn about trims really is how to change it. Set your controls up so you can trim and NEVER use combat trim. Learn how to trim to go fast and then learn how to trim for combat and remember that as the fight slows down you will always have to re-trim. Dont forget to retrim for speed after you are finished fighting.
I'm too lazy. I just use combat trim 95% of my time in Aces High. I only trim manually temporary on a few occasions: Going >450 in a 109, or being very slow with flaps out on a F4U for example.
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OK one of you techie can jump in here.... :D
As I understand it from some comments here - "trim" WILL help/totally take the load off the pilots controls so that it is "easier" physically on him. Fair enuff and understood.
At the same time it brings the planes "axis's into optimum alignment with the direction of flight so that there is minimum drag created (best angle of attack to direction of air flow over the control surfaces). If this is true them "trim" MUST IMO have some "efficiency" factor to the overall performance of the vehicle.(however minor) OR could it have a major effect??
If there is NO effect to aircraft efficiency then it would seem with "fly-by-wire" set ups in todays aircraft (NO load on pilot at all) modern aircraft would have no need to "trim" at all - Can somone please comment on this?
...technodweeb here eh! :confused: