Another Poll

[easymo]

 I get a little trim from time to time.

[This message has been edited by easymo (edited 08-23-2000).]

[funked]

Hblair - yes trim tabs have the effect of reducing stick forces.  That's why they exist.  There are many stories of WW2 pilots using pitch trim in a dive to make a recovery easier.

Control surface tabs can generate large amounts of force at high speeds.  Because the tabs are on the trailing edge (distant from the hinge axis), they can exert a larger hinge moment than the rest of the control surface.

Balance tabs (tabs with a linkage that causes them to deflect at an equal and opposite angle to the control surface deflection) were used with great effect on the F4U to reduce aileron and elevator forces at high speeds.

Many post-WW2 planes used servo tabs (tabs whose deflection is controlled by the pilot's stick deflection).  This was a very effective method to control large high-speed aircraft (e.g. 707) before hydraulic actuation of primary control surfaces was perfected.

There are other variations (spring tabs, geared tabs, probably some others I'm forgetting) that were used too.

[This message has been edited by funked (edited 08-23-2000).]

[hblair]

 

Originally posted by Nash:
It's what makes you a great trainer.

<S> hblair

Too kind, too kind, now, where did you say I had to send the money?  

[tshred]

The trim should help you get out of a compression situation, but it should not let you get more turn when your elevator is at the stops! The trim is NOT modeled correctly, and probably never will be.

One test: go inverted. Reduce speed, center elevator trim (I assume this should be neutral, or the trim tab even with the control surface)and reduce power until you have stick at full deflection and maintain altitude. Now, dial in some down elevator trim and watch your nose magically climb for the sky!

Trim tabs reduce the amount of force required at the stick to move the control surface by deflecting in the opposite direction of the control surface, therefore doing some of the work for you.

Now the way I understand it, HTC has modeled the controls so that when you are at hi speed even tho you give full control input, the control surface actually moves only a percentage of deflection based on what the stick force should be with that set of flight conditions are at the time of input, this way simulating the amount of force it took to move the stick. Warbirds did it different by programming a delay to simulate this (as I understand it to the best of my recollection) and we eneded up with what many called 'Mush Birds' which I agree with, it didn't feel real and still doesn't to me, and I find my self overcorrecting all the time trying to line up a decent shot.

The way HTC has it modled now works just fine at hi speed, and you should be able to use trim to pull out of a dive. But when you've got the elevator 'on the stops' you shouldn't be able to get any more deflection by using the damn trim! I posted about this sometime back, wasn't in the general forum, and punted it back to the top a couple times hoping to hear a reply back from HTC, but no response. So I'm assuming it's a programming limitation, one that we'll have to deal with.

So, next time your low and slow in a turn fight and you use your trim to turn tighter, remember your just 'gaming the game' like all the rest of the so called 'dweebs'(of course I include myself in this well respected group of individuals, trim mapped to stick and constanly in use, but that's just cause I'm used to trimming all the time in my own plane).

Use trim at all speeds in a fight and you will find you get much smoother control input, plus you will conserve as much E as possible unless of course all you do is 'yank and bank'    .

ts

[This message has been edited by tshred (edited 08-24-2000).]

[This message has been edited by tshred (edited 08-24-2000).]

[funked]

Tshred has a good point - at speeds where elevator deflection is limited by the stops (instead of stick forces) then trim shouldn't make a difference.

Except for Fw 190 or Ju 88, which had adjustable stabilizers for pitch trim.

[This message has been edited by funked (edited 08-24-2000).]

[Jigster]

I don't have enough thumbs to work trim and fight at the same time  

To busy fediddlein with the views or flaps to worry about trim.

- Jig

[Vermillion]

Strange, but I usually have the stall horn buzzing long before I hit the stops on my joystick, if I need too.

Never needed or thought of using trim to get more stick deflection in the planes I fly.

------------------
Vermillion
**MOL**, Men of Leisure
"Real Men fly Radials, Nancy Boys fly Spitfires"

[Hajo]

I use the 2nd hat switch on my F-16 Combat stick for aileron and elevator trim....keyboard for the rudder.  Really helps when ya want to keep the nose down in a high speed dive in a plane that doesn't compress easily like the FW190

[Andy Bush]

hblair

LOL!! I'm here...just reading this and trying to stay out of the way! I thought most of this was hashed over in that previous thread.

As for the question...I have all three trim controls mapped to my F22. BTW, I switched the hats on my F22...moving the white 'coolie' hat to the 'BTN H3' position to use it to switch views (with my hand on the hand rest, I couldn't reach the top hat(BTN H1) easily). I placed the original BTN H3 black hat where the white hat had been...and use it for elevator and aileron trim. I mapped the rudder trim to the right/left positions of the BTN H2 switch.

As for how trim works in RL versus this sim...well, it's a complicated subject! As funked noted, there are a number of trim set-ups...and they do different things in different airplanes. I'll try to sort things out (realizing that terminology changes from manufacturer to manufacturer or sim to sim!).

To begin with, we have to understand what 'trim' was meant to do in the first place. As a generic term, 'trim' is a secondary flight control device intended to relieve stick and rudder forces. The pilot flys his a/c in a certain attitude at a certain speed...holding this attitude and speed requires the controls (aileron, elevator, and rudder) to be displaced some amount from their neutral position. The pilot 'feels' this displacement in the form of stick and rudder 'heaviness' or 'pressure'. The pilot then moves the appropriate trim control until he no longer 'feels' that 'pressure'...at this point the a/c is then 'trimmed' (but only for this exact attitude and airspeed).

In most WW2 a/c, these secondary flight controls (trim) came in three forms. One was a movable tab on the trailing edge of the aileron/elevator/rudder. These were actuated by the pilot using knobs or wheels on the cockpit left console. Second, some WW2 a/c (like the Me-109), provided pitch trim through the use of a movable horizontal stabilizer - the horizontal stabilizer was moved up and down by a jackscrew actuated by a wheel on the left console. For these a/c, there were usually no tabs on the elevator itself. Lastly, some aircraft had small tabs on the trailing edges of the three control surfaces that were adjustable only by 'bending' them prior to flight. This was something usually done when the a/c was first made and test flown...the test pilot would land and report a tendency to roll, pitch, or yaw in level flight. Then then tabs would be 'bent' to correct this. The a/c would be flown again to test the effectiveness of the tab position. Once the a/c maintained stable flight, these tabs were normally left in that position.

Regardless of which type of trim mechanization, in RL, trim does only one thing...reduce control forces thereby lessening pilot work load. On the other hand, in AH, we know that elevator trim may actually increase turn performance...this is a peculiarity of this sim...and that's that! To achieve best turn performance (min radius/max rate), the AH pilot should learn how to use elevator trim.

There continues to be some mention of 'compressibility'. I think we need to differentiate between the effects of 'compressibility' and resistance due to airflow over the flight control surfaces at high speeds. The two are completely separate.

Compressibility deals with what happens to an aircraft as it approaches Mach 1. This is a complicated subject...let's just say that  typically in WW2 a/c, the pilots noticed that their flight controls became less and less effective at very high speeds. This is NOT a problem of not being able to move the flight controls as such...it is an aerodynamic issue relating to airflow characteristics over the aircraft structure.

Now, resistance due to high speed air flow is a different matter. Imagine trying to open a car door while going fast...it's much harder to do than when the car is standing still. The same thing happens to many WW2 a/c. As they go faster, the controls 'stiffen' or get harder to move. This a mechanical problem...the pilot loses the  ability to physically move the flight control because of the force of high speed air flow over that control surface. In those a/c that have pilot-actuated trim devices (tabs or movable horizontal stabilizer), the pilot may be able to enhance his ability to roll or pitch under these conditions by using trim. But please note...this 'works' only because the pilot can still operate the trim surface at high speed using his trim controls...the trim device retains a strong enough 'mechanical advantage' to be able to be moved regardless of the high speed air resistance. This is why elevator trim can be used to pull out of high speed dives.

Anyway!! The AH pilot that wants to maximize his performance should use his trim controls to gain that last tiny bit of advantage...whatever it takes to kill the bandit!

Andy

   

[Duckwing6]

i have trim programmed to the buttons on MS Pro..

AFAIK the trim in AH is moddeled in that way that it "shifts" the possible deflection with the neutral point of the control surface . E.g you can't reach the full forward deflection of the conrol surface when you have full nose UP trim for example.. not exactly the way RL trim works...

i might be wrong tho  

DW6

[Andy Bush]

DW6

You are not wrong!

The range of movement in control surfaces may well be limited by the trim function.

A good example is when the trim function is performed by a movable horizontal stabilizer. Let's imagine the pilot trimming the nose 'up'...the leading edge of the horizontal stabilizer would then be moved down. It is possible that when the stabilizer is at its most 'down' position (max nose up trim), that the range of movement of the elevator is less than it would be at the neutral trim position.

Andy

[Minotaur]

You can increase turn rate in AH using elevator trim.  This is noticable during stall fights.  

During beta, you could perform 90 degree turns almost instantaneously.  Meaning, verticle dive to horizontal flight by pulling G's that were off the scale.  This was done by using AutoLevel and something the normal flight controls could never even come close to accomplishing.

I think HTC will tweak this some more over time to continually fine tune this effect.  


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Mino
The Wrecking Crew

"OUCH!!!  It hurts to bite your tongue."
Popeye

[-towd_]

1500 unexplainable miricle turns are now explained . always wondered how they did the miricle turn.

htc will hopefully fix that crap with trim givin you a better turn radius.

i use trim to get our of dives and in a 109 it is mapped to a hat on my saitek x36 usb