Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: MK-84 on January 11, 2012, 01:30:19 AM
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I understand the basics on this, but would someone explain why I would pick one or the other given a flying situation.
I'm asking in terms of a typical MA pilot.
I always fly with it on, but am I missing something interesting?
Krusty? AKAK?
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In a fight, you can maneuver better. It causes drag situations, as the automatic-ness is constantly maintaining what it is trying to achieve when set on.
Turned off, then, you will need to manually trim it out, which changes due to altitude, speed, etc.
I have my Combat Trim as a button mapped as an on/off toggle.
There is write-up somewhere in the training section, and probably in the wiki.
I think CT is Aces High way of dealing with a PC simulation's characteristics mimicing real life.
I usually have it on, but then as needed.
I remember a guy wrote up a sortie taking out his P-47 and how he used combat trim as needed and why.
Do a search here to AH Forums.
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Combat trim simulates a pilot manually trimming his aircraft. It works fine at most speeds but can cause issues when you're too fast or very slow because combat trim assumes you want to fly straight at your current speed.
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I understand the basics on this, but would someone explain why I would pick one or the other given a flying situation.
I'm asking in terms of a typical MA pilot.
I always fly with it on, but am I missing something interesting?
Krusty? AKAK?
In almost all cases having it on is easier. Even if it is on , you simply press any trim key and it is off.
In dives with planes like the 109,if the plane is trimmed for high speed of the dive, pulling out will be difficult vs trimming for a slower speed and holding the stick forward in the dive, then more elevator is available for the pull out. But this can be accomplish by trimming before the dive or pull out with combat trim on. But it can also be simpler to simply have the trim set at say 300, then not having to move it during a fight.
Buckaroo stating it causes drag in situations is incorrect, it makes no difference if the plane is trimmed, or the controls are moved with the stick / rudder. The drag will be the same as long as the plane is in the same state.
HiTech
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Also, correct me if I'm wrong, the combat trim will try to trim you for level flight if you deploy flaps, which will give u fits when dropping your flaps to make a shot. I fly with CT on & have to try & remember to disengage the CT before the fight or at the very least disengage as I deploy the flaps. This may not be right, as I would think maybe the game could auto shut off the CT when flaps are used just as if you were to hit one of the trim commands. Any ideas?
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My rule of thumb is on until the stall fight starts. Then it seems, again a perception, to make the plane less agile at slowe speeds and high AOA.
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Also, correct me if I'm wrong, the combat trim will try to trim you for level flight if you deploy flaps, which will give u fits when dropping your flaps to make a shot. I fly with CT on & have to try & remember to disengage the CT before the fight or at the very least disengage as I deploy the flaps. This may not be right, as I would think maybe the game could auto shut off the CT when flaps are used just as if you were to hit one of the trim commands. Any ideas?
Combat trim does not change with flap changes.
Combat trim is extremely simple, it simply moves trim tabs to position y for speed x. When ever you are going 150 mph the tabs will always be at the same position as any other time you are at 150.
HiTech
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I keep it on all the time except only when I am in a high speed dive, especially when dive bombing. Many aircraft are adversely effected by the CT once a certain speed it reached, as it automatically raises the nose up (rather abruptly I may add) and effects the pitch of the aircraft. I notice it most in the Typhoon and Mossi Mk IV. Once I have the nose back up I toggle the CT back on, rinse and repeat if need be.
While in the air doing the air vs air thing, I always keep it on. I only toggle CT off when in the high speed dives.
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Combat trim does not change with flap changes.
Combat trim is extremely simple, it simply moves trim tabs to position y for speed x. When ever you are going 150 mph the tabs will always be at the same position as any other time you are at 150.
HiTech
I'm trying something new (for me) based on somebody telling me it works. Don't know for sure yet, but it looks promising:
When in a tight turn fight, I use manual full up elevator trim to turn tighter than possible with auto combat trim on. I think I've noticed that I can get around the top of loops quicker also. Once the fight is over I turn auto combat trim back on.
All the while I use flaps as necessary as well, but as little as possible.
Sound right? :headscratch:
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I'm trying something new (for me) based on somebody telling me it works. Don't know for sure yet, but it looks promising:
When in a tight turn fight, I use manual full up elevator trim to turn tighter than possible with auto combat trim on. I think I've noticed that I can get around the top of loops quicker also. Once the fight is over I turn auto combat trim back on.
All the while I use flaps as necessary as well, but as little as possible.
Sound right? :headscratch:
Using elevator trim to turn tighter is an AH urban myth that has been debunked many times in the past. Just do a search for the threads to see for yourself.
ack-ack
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I understand the basics on this, but would someone explain why I would pick one or the other given a flying situation.
I'm asking in terms of a typical MA pilot.
I always fly with it on, but am I missing something interesting?
Krusty? AKAK?
In practice if I'm flying a hog and I get in a fight where I'm using a lot of flaps and getting slow- say a rolling scissors - I find the CT will be pulling the nose up around the bottom of the scissors and I'll have to fight it by pushing forward on the stick if I'm trying to line up on the enemy plane.
To fix this I keep my elevator trim slider pushed most of the way forward all of the time (trimmed roughly for around 300 as Hitech said above.) Then when I shut off CT I'm already manually trimmed nose heavy, which seems to stop the tendency of the nose to rise with flaps out at slow speed.
To keep things simple I usually shut off CT as soon as I get in a fight.
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Using elevator trim to turn tighter is an AH urban myth that has been debunked many times in the past. Just do a search for the threads to see for yourself.
ack-ack
Searched and read a lot of opinions and unrelated posts regarding combat trim. I think it would be very useful to state whether this is true or not in the help or training section. I really did think it was pulling me around faster using full elevator up trim, but I don't know for sure. Who would know for sure? HiTech?
:noid
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You can't trim more than you can already move the surfaces. It's not like you have a range of -100 to +100, and trimming can give you an additional 10 on either side of the range to make it -110 to +110.
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You can't trim more than you can already move the surfaces. It's not like you have a range of -100 to +100, and trimming can give you an additional 10 on either side of the range to make it -110 to +110.
Speaking specifically about Spitfires... since the elevator trim tabs are seperate moveable (although small) surfaces on the elevator, when you have full elevator up and then move the tabs full up, why wouldn't that give you more than if you had full elevators up and trim tabs level with the elevators? :headscratch:
Not trying argue here, I just want to know the facts vs opinions and it's hard to tell fact from opinion, on occasion. :frown:
(http://www.mark-1-spitfire.co.uk/jpgs/mk-9-spitfire-439-15b.jpg)
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Speaking specifically about Spitfires... since the elevator trim tabs are seperate moveable (although small) surfaces on the elevator, when you have full elevator up and then move the tabs full up, why wouldn't that give you more than if you had full elevators up and trim tabs level with the elevators? :headscratch:
When you set full trim up the trim tab is actually down in order to force the elevator up.
As was already mentioned, trim cannot increase turn rate.
...To fix this I keep my elevator trim slider pushed most of the way forward all of the time (trimmed roughly for around 300 as Hitech said above.) Then when I shut off CT I'm already manually trimmed nose heavy, which seems to stop the tendency of the nose to rise with flaps out at slow speed...
Shiv you can take this a bit further and trim for 0 G at cruise speed. This makes it easier to hit 0 G for max accelleration, just release the stick, and tends to be close to level trim at max speed.
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Shiv you can take this a bit further and trim for 0 G at cruise speed. This makes it easier to hit 0 G for max accelleration, just release the stick, and tends to be close to level trim at max speed.
Ah, I think I see. I'll give it a try, thanks FLS.
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Searched and read a lot of opinions and unrelated posts regarding combat trim. I think it would be very useful to state whether this is true or not in the help or training section. I really did think it was pulling me around faster using full elevator up trim, but I don't know for sure. Who would know for sure? HiTech?
:noid
You may want to go to a web site for flight training, and read what an elevator trim tab is used for. That might help explain the concept for you.
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You may want to go to a web site for flight training, and read what an elevator trim tab is used for. That might help explain the concept for you.
http://www.flightlearnings.com/2009/09/12/secondary-flight-controls-part-four-–-trim-tabs/
Just did, and it does. Thank you. :salute
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When you set full trim up the trim tab is actually down in order to force the elevator up.
As was already mentioned, trim cannot increase turn rate.
Ok, again... just so I fully understand this...
I do understand the use of trim tabs and how their opposite deflection from the elevators removes stick pressure, but in terms of just the aerodynamics (of which I know little if anything)... if I have elevators full up position and hold them there with sufficient force that they won't move on their own.... and then I dial elevator trim tabs full down (trim tabs move up full deflection also), wouldn't I get a greater nose up angle?
In other words, seems like trim tabs can give you more, but you have to move them opposite of what you would think and hold the elevators in place (not allow the trim tabs to counter the elevator movement).
If all that true, then I should use opposite manual trim to maximize full nose up. Correct? If not, why not since the trim tabs would now add aerodynamically to the elevator's positioning the nose up?
:headscratch:
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I keep it on all the time except only when I am in a high speed dive, especially when dive bombing. Many aircraft are adversely effected by the CT once a certain speed it reached, as it automatically raises the nose up (rather abruptly I may add) and effects the pitch of the aircraft. I notice it most in the Typhoon and Mossi Mk IV. Once I have the nose back up I toggle the CT back on, rinse and repeat if need be.
While in the air doing the air vs air thing, I always keep it on. I only toggle CT off when in the high speed dives.
Great description...I agree 100%. I played for so long with CT on and like you said, in a dive as your speed increases you rnose does begin to pull up as you said very abruptly and can cause accuracy, as you said, divebombing or strafing to below 50% in some situations. Lately, I have found that when I am divebombing I take CT off and my accuracy is something like 4 outta 5 as compared to maybe 2 or 3 outta 5 at given altitudes. It would be interesting to have someone run some tests...maybe Ill take the time and go into Offline or the TA and run maybe 20 runs with CT on/off and Ill post the results.
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Searched and read a lot of opinions and unrelated posts regarding combat trim. I think it would be very useful to state whether this is true or not in the help or training section. I really did think it was pulling me around faster using full elevator up trim, but I don't know for sure. Who would know for sure? HiTech?
:noid
Again, if you were to stop typing on Channel 200 long enough and search the forums, you'll see that you are incorrect in your perception of using elevator trim to turn tighter in a turn. You'll even see HiTech's comments in many of those threads debunking the myth.
This debate is nothing new and comes up every so often and is debunked each time.
ack-ack
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Again, if you were to stop typing on Channel 200 long enough and search the forums, you'll see that you are incorrect in your perception of using elevator trim to turn tighter in a turn. You'll even see HiTech's comments in many of those threads debunking the myth.
This debate is nothing new and comes up every so often and is debunked each time.
ack-ack
Ok, I read every hitech post re trim. It still doesn't explain why having full up elevator, holding that and then adding opposite trim to move the trim tabs up as well would not move the nose higher. I understand it would require more force to hold the elevators since the trim tabs would try to work against you, but the point is by creating more force by adding trim tabs that add to the angle of the elevators you should get more nose up angle.
Elevators deflected up with trim tabs deflected up should equal more force pushing the tail down and nose up.
If not, why not? :headscratch:
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Ok, again... just so I fully understand this...
I do understand the use of trim tabs and how their opposite deflection from the elevators removes stick pressure, but in terms of just the aerodynamics (of which I know little if anything)... if I have elevators full up position and hold them there with sufficient force that they won't move on their own.... and then I dial elevator trim tabs full down (trim tabs move up full deflection also), wouldn't I get a greater nose up angle?
In other words, seems like trim tabs can give you more, but you have to move them opposite of what you would think and hold the elevators in place (not allow the trim tabs to counter the elevator movement).
If all that true, then I should use opposite manual trim to maximize full nose up. Correct? If not, why not since the trim tabs would now add aerodynamically to the elevator's positioning the nose up?
:headscratch:
Your missing a key concept. The elevator is what controls the nose of the aircraft. The trim tab controls the pressure you feel fed back through the control. Understand. If the elevator is deflected 100% that’s all there is , changing the trim tab does not give you more elevator deflection. You only get 100%. What the trim tab gives you is the ability to make an elevator deflection of 100% with only using 50% of your muscle power. Get it. It removes or lowers the amount of muscle power you need to use to get 100% deflection?
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Your missing a key concept. The elevator is what controls the nose of the aircraft. The trim tab controls the pressure you feel fed back through the control. Understand. If the elevator is deflected 100% that’s all there is , changing the trim tab does not give you more elevator deflection. You only get 100%. What the trim tab gives you is the ability to make an elevator deflection of 100% with only using 50% of your muscle power. Get it. It removes or lowers the amount of muscle power you need to use to get 100% deflection?
I believe I fully understand that. But think of it in reverse. If you use opposite trim it requires more muscle. Why?
I think it is because you're getting more nose up force requiring you to offset with the additional muscle effort.
Also, I am not saying you would get more elevator deflection, I am saying the trim tabs would add to what the elevators are already doing. -- lower the tail, raise the nose further.
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I believe I fully understand that. But think of it in reverse. If you use opposite trim it requires more muscle. Why?
I think it is because you're getting more nose up force requiring you to offset with the additional muscle effort.
Also, I am not saying you would get more elevator deflection, I am saying the trim tabs would add to what the elevators are already doing. -- lower the tail, raise the nose further.
What makes the aircraft turn? If your answer is anything other then lift, your wrong.
The elevator controls the AOA of the wing, Excessive lift, equal climb, Roll the aircraft left or right and excessive lift = a turn.
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What makes the aircraft turn? If your answer is anything other then lift, your wrong.
The elevator controls the AOA of the wing, Excessive lift, equal climb, Roll the aircraft left or right and excessive lift = a trun.
Yes and I believe moving the trim tabs in the same direction as the elevators would give you more AOA. :headscratch:
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Yes and I believe moving the trim tabs in the same direction as the elevators would give you more AOA. :headscratch:
It doesn't.
ack-ack
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It doesn't.
ack-ack
:huh Why?
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ack-ack is 100% correct. all using trim does is lower the forces you need to use to move the elevator to reach critical AOA.
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ack-ack is 100% correct. all using trim does is lower the forces you need to use to move the elevator to reach critical AOA.
Just made a paper aeroplane, gave it elevators and gave it trim tabs on the elevators. It loops up faster with trim tabs deflected up and elevators deflected up. :banana:
:old: when lacking a full explanation, experimental evidence helps, on occasion.
:D
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Just made a paper aeroplane, gave it elevators and gave it trim tabs on the elevators. It loops up faster with trim tabs deflected up and elevators deflected up. :banana:
:old: when lacking a full explanation, experimental evidence helps, on occasion.
:D
if it was to scale, yes, I’d agree with you, however, I would not stake my life on it.
I've run across more then a few students pilots who found it difficult to accept the correct answer even when it was pointed out by many that they were just wrong in their thinking. With them it’s easy, I just point out that they have to take the FAA written pilot exam and they can’t take it without my signoff. And I don’t signoff on students that don’t understand basic concepts.
Some even go so far as to parrot back the correct answer for signoff but then go put down the wrong answer on the test. There the very best of the special students. I enjoy them the most. The first written test is free, but re-test is $150.00 and of course there is ground school, additional flight lessons at $175.00 a pop. I call those student “Money in the pocket”. Like my Dad told me once, “Can’t fix stupid”.
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Midway a better experiment would be to time your max performance turns with and without the trim tab up.
The basic mistake you're making is thinking that turn rate is limited by elevator deflection. Since you can already stall or black out with max deflection there is no need to increase it. Turn rate is limited by speed and AOA. Elevators are designed with more than enough deflection to provide max AOA. Exceeding max AOA just stalls you.
If you scale your stick then trimming might make it easier to control your AOA near the critical stall point but it won't increase your max turn rate.
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Ah, I think I see. I'll give it a try, thanks FLS.
Since required trim changes with speed it won't be exact but it lets you get close while keeping your eyes outside the cockpit.
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Traveler: Excessive lift does not = climb ( i think I saw you write this) when wings level , excess lift = pitch up. In a steady state climb I assume you know you need less lift then when in level flight.
As to Midway's strange question of will full down trim when holding full back stick give you better turn performance.
First the question poses many unknowns and assumptions.
1. Unless you were very slow there are not many planes you could have full trim and have enough strength to move the control full opposite direction.
2. If full elevator already stalls the more aoa/elevator will not help your turn.
So on to the real question. Does full down trim when the elevator is fully deflected up , increase the AOA.
My guess is , it would increase the AOA if it could be done.
In AH it does not.
HiTech
HiTech
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Plus, the trim tab is so small I don't think it would add a noticeable amount to the deflection anyway. The only reason it's as effective as it is at it's job is because it's at the end of the elevator, where it has a mechanical advantage.
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Traveler: Excessive lift does not = climb ( i think I saw you write this) when wings level , excess lift = pitch up. In a steady state climb I assume you know you need less lift then when in level flight.
I did write it and I didn’t want to confuse Midway with the different components of lift, I was speaking in the terms of the sum total sum of all upward forces of lift, frequently, much of the difficulty encountered in explaining the forces that act upon an airplane is largely a matter of language and its meaning. For example, pilots have long believed that an airplane climbs because of excess lift. This is not true if one is thinking in terms of wing lift alone. It is true, however, if by lift it is meant the sum total of all “upward forces.” But when referring to the “lift of thrust” or the “thrust of weight,” the definitions previously established for these forces are no longer valid and complicate matters. It is this impreciseness in language that affords the excuse to engage in arguments, largely academic, over refinements to basic principles.
Having no idea of Midways background or education in aviation matters I chose to use and speak in terms that had a long standing understanding by the general public, if somewhat imprecise I thought he would understand the concept.
No matter what words we use or what we call it, it still comes down to Newton’s third law, right.
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Midway a better experiment would be to time your max performance turns with and without the trim tab up.
The basic mistake you're making is thinking that turn rate is limited by elevator deflection. Since you can already stall or black out with max deflection there is no need to increase it. Turn rate is limited by speed and AOA. Elevators are designed with more than enough deflection to provide max AOA. Exceeding max AOA just stalls you.
If you scale your stick then trimming might make it easier to control your AOA near the critical stall point but it won't increase your max turn rate.
:O This I understand! Thank you, FLS.
You're saying that turn rate is limited by stall/blackout and you can get there using just elevators, adding trim tab deflection to get to that AOA is pointless since you can get there with the elevators alone. :aok
I understand now.
Forgive me, my education in things aerodynamic is very very limited and I tend to keep pushing the bounds of my idea until I get an answer that I can comprehend. I understand this one and HiTech's comments above reinforce it.
Thank you gentlemen for helping this aerodynamically uneducated AH pilot comprehend this. :salute :rock
:cheers: :bolt:
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if it was to scale, yes, I’d agree with you, however, I would not stake my life on it.
I've run across more then a few students pilots who found it difficult to accept the correct answer even when it was pointed out by many that they were just wrong in their thinking. With them it’s easy, I just point out that they have to take the FAA written pilot exam and they can’t take it without my signoff. And I don’t signoff on students that don’t understand basic concepts.
Some even go so far as to parrot back the correct answer for signoff but then go put down the wrong answer on the test. There the very best of the special students. I enjoy them the most. The first written test is free, but re-test is $150.00 and of course there is ground school, additional flight lessons at $175.00 a pop. I call those student “Money in the pocket”. Like my Dad told me once, “Can’t fix stupid”.
I would never do this. I would keep pushing you or research on my own until I comprehend the concepts. The key for me is to understand why I'm wrong, not just that I'm wrong. I was pretty sure I was wrong since you all are experts and I am not (in this field), but I didn't want to change my view of it because somebody told me to (ACK ACK), I want to change it because I understand it. Which I now do.
Thank you, sir, for trying to help me. I learned something today. Nice. :aok
:old: :airplane: :joystick:
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So how do the ailerons on a zero work?
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I would never do this. I would keep pushing you or research on my own until I comprehend the concepts. The key for me is to understand why I'm wrong, not just that I'm wrong. I was pretty sure I was wrong since you all are experts and I am not (in this field), but I didn't want to change my view of it because somebody told me to (ACK ACK), I want to change it because I understand it. Which I now do.
Thank you, sir, for trying to help me. I learned something today. Nice. :aok
:old: :airplane: :joystick:
Everyone tries to be helpful, but you might have been better served to have just stated in plain English, I don’t understand can someone explain it to me, instead of continually stating an incorrect concept as being the correct choice.
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So how do the ailerons on a zero work?
What do you mean? Do they have a unique design?
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Everyone tries to be helpful, but you might have been better served to have just stated in plain English, I don’t understand can someone explain it to me, instead of continually stating an incorrect concept as being the correct choice.
Ah, but I was correct that full down trim, deflecting trim tabs up, would raise the nose further adding to what up elevators are doing assuming you had the required muscle or hydrolic power. In other words AOA would increase. It is just not necessary since you can achieve stall or blackout with just the elevators. So the concept was correct, just not doable except at very low speed where a stall would likely occur before the trim tabs add to AOA. I do understand this is an odd way of looking at it due to my lack of any flight school experience.
Anyways on my original question, I have an answer that makes complete sense to me now. Trim tabs offer no increased slow speed turn performance in AH, which differs from what someone told me in AH Elevators will take you to the stall or blackout limit.
:)
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Just to take this one step further. Given that trim tabs can add to AOA, if the elevators froze in a neutral position and could not move for some mechanical breakdown reason, then dialing elevator trim tabs down (deflecting them up) would be a way to get your nose up, although it would only do so slowly due to the small size of the tabs.
Correct? :pray
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Just to take this one step further. Given that trim tabs can add to AOA, if the elevators froze in a neutral position and could not move for some mechanical breakdown reason, then dialing elevator trim tabs down (deflecting them up) would be a way to get your nose up, although it would only do so slowly due to the small size of the tabs.
Correct? :pray
That would be my guess.
HiTech
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That would be my guess.
HiTech
:)
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Just to take this one step further. Given that trim tabs can add to AOA, if the elevators froze in a neutral position and could not move for some mechanical breakdown reason, then dialing elevator trim tabs down (deflecting them up) would be a way to get your nose up, although it would only do so slowly due to the small size of the tabs.
Correct? :pray
Realistically, given their size, they probably wouldn't do anything remotely noticeable. They have no chance of overpowering the elevators themselves, so it would be safe to say that they would be ineffective in controlling the aircraft, but I guess in theory, they would generate some sort of lift if deflected...
Your best bet if your elevators are frozen in controlling the aircraft would be through throttle control.
Side note:
This actually happened to an Airbus carrying cargo over Iraq or Afghanistan a year or two ago. They got tagged by a SAM, and lost authority on all of their control surfaces. They were trimmed out for a climb at 250 or 300 knots (can't remember) and flew the plane to the nearest airport and crash landed safely using just engine controls.
http://www.spacedaily.com/news/iraq-03a.html
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Just to take this one step further. Given that trim tabs can add to AOA, if the elevators froze in a neutral position and could not move for some mechanical breakdown reason, then dialing elevator trim tabs down (deflecting them up) would be a way to get your nose up, although it would only do so slowly due to the small size of the tabs.
Correct? :pray
I take it that in your hypothetical the elevator failure took place with the aircraft trim already set for straight and level flight with airspeed at a constant.
In any other flight condition you might only be able to slow a decent by trimming up or increase the decent by trimming down, in the case where the aircraft was trimmed for a decent. Like wise the same issues for an aircraft trimmed for a climb.
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In any other flight condition you might only be able to slow a decent by trimming up or increase the decent by trimming down, in the case where the aircraft was trimmed for a decent. Like wise the same issues for an aircraft trimmed for a climb.
He is asking if it is opposite of what you state. I.E. trim down to slow the decent.
HiTech
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He is asking if it is opposite of what you state. I.E. trim down to slow the decent.
HiTech
my bad, I assumed he was talking in terms of triming for the positon of the nose of the aircraft, up or down.
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Descent*
Sorry, it was bugging me.
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my bad, I assumed he was talking in terms of triming for the positon of the nose of the aircraft, up or down.
He is stating that normal trimming, when adjusting the trim for up will raise the nose. If the elevator is frozen turning the trim tab for up ,will now lower the nose unlike normal trimming conditions.
HiTech
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He is stating that normal trimming, when adjusting the trim for up will raise the nose. If the elevator is frozen turning the trim tab for up ,will now lower the nose unlike normal trimming conditions.
HiTech
Yes, I got you, as long as the elevator was failed set for level flight, yes, it’s the reverse, trim nose down , the trim tab acts like a mini elevator and the nose would rise.
thanks
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Descent*
Sorry, it was bugging me.
yes, thanks
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In almost all cases having it on is easier. Even if it is on , you simply press any trim key and it is off.
In dives with planes like the 109,if the plane is trimmed for high speed of the dive, pulling out will be difficult vs trimming for a slower speed and holding the stick forward in the dive, then more elevator is available for the pull out. But this can be accomplish by trimming before the dive or pull out with combat trim on. But it can also be simpler to simply have the trim set at say 300, then not having to move it during a fight.
Buckaroo stating it causes drag in situations is incorrect, it makes no difference if the plane is trimmed, or the controls are moved with the stick / rudder. The drag will be the same as long as the plane is in the same state.
HiTech
Thank you for the clarification.
My bad.
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Just to take this one step further. Given that trim tabs can add to AOA, if the elevators froze in a neutral position and could not move for some mechanical breakdown reason, then dialing elevator trim tabs down (deflecting them up) would be a way to get your nose up, although it would only do so slowly due to the small size of the tabs.
Correct? :pray
I'd think that it would only be possible for reversed-trim tabs to increase AoA if the mechanical design of the elevator caused it to be impossible for the elevator to be deflected to the point where it becomes less effective.
Pulling up elevator forces the tail down and increases the AoA of the wing. However, it's not necessarily a situation where "more is more effective". Beyond a certain "xx" degrees of deflection, the elevator is just going to increase drag without doing any more to lower the tail (or at least the ratio of "drag induced to performance increase" will worsen).
Imagine if you could move the elevator to 90 degrees straight up deflection (in relation to the stabilizer). It would cause a huge amount of drag, but wouldn't add any more AoA than "xx" degrees had. What is the "magic" point where more deflection equals more drag but equal or lesser-than maximum effectiveness?
To see what I mean drive your car with the window open and stick your hand out in the slipstream, palm down. Rotate your hand so that it "flies". Continue to increase the angle of rotation until you hit the point where your hand is palm-forward. At some point in there you'll no longer be "gaining lift" and will instead just be "gaining drag".
I would expect that a designer would give you enough deflection in the initial design to reach "best, most-effective" elevator deflection under "normal" control inputs... Plus some more deflection, "just in case". If that's the case, then going full-up deflection and then dialing-in "down" elevator trim would just take you further into the "more drag for less performance" realm.
Keep in mind that the drag induced at extreme elevator deflection is going to lower your speed as well, which makes it tougher (or impossible) to keep your nose up...
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Mtnman in the bit you quoted he's talking about the elevator not moving, frozen level so it acts like a stabilizer extension, and the trim tabs acting as tiny little elevators. You seem to be responding to his original question.
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I'd think that it would only be possible for reversed-trim tabs to increase AoA if the mechanical design of the elevator caused it to be impossible for the elevator to be deflected to the point where it becomes less effective.
Pulling up elevator forces the tail down and increases the AoA of the wing. However, it's not necessarily a situation where "more is more effective". Beyond a certain "xx" degrees of deflection, the elevator is just going to increase drag without doing any more to lower the tail (or at least the ratio of "drag induced to performance increase" will worsen).
Imagine if you could move the elevator to 90 degrees straight up deflection (in relation to the stabilizer). It would cause a huge amount of drag, but wouldn't add any more AoA than "xx" degrees had. What is the "magic" point where more deflection equals more drag but equal or lesser-than maximum effectiveness?
To see what I mean drive your car with the window open and stick your hand out in the slipstream, palm down. Rotate your hand so that it "flies". Continue to increase the angle of rotation until you hit the point where your hand is palm-forward. At some point in there you'll no longer be "gaining lift" and will instead just be "gaining drag".
I would expect that a designer would give you enough deflection in the initial design to reach "best, most-effective" elevator deflection under "normal" control inputs... Plus some more deflection, "just in case". If that's the case, then going full-up deflection and then dialing-in "down" elevator trim would just take you further into the "more drag for less performance" realm.
Keep in mind that the drag induced at extreme elevator deflection is going to lower your speed as well, which makes it tougher (or impossible) to keep your nose up...
:aok exactly how I understand it now. :salute
I got it. I understand trim now. :banana:
:)
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Mtnman he's talking about the elevator not moving, frozen level so it acts like a stabilizer extension, and the trim tabs acting as tiny little elevators.
That was my a further question to help me understand. Hitech answered it. :aok
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I understand Midway. I just thought it might be confusing for people who didn't read the whole thread.
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Mtnman in the bit you quoted he's talking about the elevator not moving, frozen level so it acts like a stabilizer extension, and the trim tabs acting as tiny little elevators. You seem to be responding to his original question.
Yup, you're correct. I was trying to respond to an earlier question but grabbed the wrong quote.
Thanks for clarifying for me! :D
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I'm sure you'll return the favor. :lol
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now thats the elevators. what about alerions and rudder wouldnt having full left aleriron then adding trim make u you roll better such as with rudder?
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now thats the elevators. what about alerions and rudder wouldnt having full left aleriron then adding trim make u you roll better such as with rudder?
It's the same deal as the trim on the elevator.
You'll eventually reach a point where more aileron deflection will make you roll WORSE (and cause you to yaw away from your intended roll, too).