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frans(at)privatepilots.nl
Guest

Posted: Wed May 12, 2010 12:08 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

On 04/12/2010 08:06 PM, Peter Zutrauen wrote:



 	  Quote: 	
		   I'm perplexed - all the photos I've ever looked at of Europas in cruise,

 the trim tab is *up* (as others have noted), thus the flying elevator is

 by definition providing *lift* to the tail.... a contradiction to my

 teachings. 


	


Let's add some more to the confusion...



Especially for those who claim never having seen an Europa with the anti

servo tab NOT in the up position, here are some pictures we took when

flying our PH-DIY in formation with the PH-JAI from Tim Weert.



As you can see on the attached pictures, the PH-DIY has the anti servo

tab perfectly in line with the rest of the tail plane (as it should be,

because it is an anti servo tab, who's task it is to drive the tailplane

until it is line with the trim tab).



Frans

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peterz(at)zutrasoft.com
Guest

Posted: Wed May 12, 2010 3:05 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

Thanks Frans!

*Very* interesting.

just a note - my original statement below is wrong - as an upward trim tab results in a downward force on the tail, not lift as I had originally (incorrectly) thought.

 questions:

- were you in stead-state constant-altitude cruise?

- where was your trim set at?

- was your stick force = 0?

- what was your cruise speed?

- what was your weight and balance (with fuel at that point in time)?

As the tailplane is a symmetrical airfoil,  my confused mind asserts that in cruise (since the horizontal stab by definition must be providing a downward force) your tailplane must have been at a negative angle of attack, and since the combination anti-servo/trim tab was in a neutral position then I would have expected a steady stick force would have needed to be applied.... or a far aft CG condition would have been needed?

Many thanks!

Pete

A239

On Wed, May 12, 2010 at 4:05 AM, Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)> wrote:

 [quote]On 04/12/2010 08:06 PM, Peter Zutrauen wrote:

 > I'm perplexed - all the photos I've ever looked at of Europas in cruise,

 > the trim tab is *up* (as others have noted), thus the flying elevator is

 > by definition providing *lift* to the tail.... a contradiction to my

 > teachings.

 Let's add some more to the confusion...

 Especially for those who claim never having seen an Europa with the anti

 servo tab NOT in the up position, here are some pictures we took when

 flying our PH-DIY in formation with the PH-JAI from Tim Weert.

 As you can see on the attached pictures, the PH-DIY has the anti servo

 tab perfectly in line with the rest of the tail plane (as it should be,

 because it is an anti servo tab, who's task it is to drive the tailplane

 until it is line with the trim tab).

 Frans

 [b]

frans(at)privatepilots.nl
Guest

Posted: Wed May 12, 2010 4:56 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

On 05/12/2010 01:03 PM, Peter Zutrauen wrote:



 	  Quote: 	
		   As the tailplane is a symmetrical airfoil,  my confused mind asserts

 that in cruise (since the horizontal stab by definition must be

 providing a downward force) your tailplane must have been at a negative

 angle of attack, and since the combination anti-servo/trim tab was in a

 neutral position then I would have expected a steady stick force would

 have needed to be applied....


	


This is an *anti servo trim tab*, if it is not in line with the

tailplane, it puts a force on the tailplane so that the tailplane

rotates until it is in line with the anti servo trim tab again.

You can easily see what I mean by exercising the trim in whatever

position, and then carefully with your hands on the anti servo tab, try

to push it in line with the tailplane again. You will see that the

tailplane rotates during this process, and that you will always end up

with the anti servo tab in line with the tailplane.

This is true for *any* speed, *any* CG, etc, except when the pilot

exercises some force on the stick. Any force on the stick gets into the

equation and disturbes this balance.

If you trim for a specific speed, all you do is put the stick in a

specific position, and then with the trim button, line up the anti servo

tab with the tailplane, to keep the tailplane at its new position. You

will always end up with the anti servo tab in the same relative position

of the tailplane.



The real confusion is that there are people flying around with the anti

servo tab not in line with the tailplane. This means they are either

pulling or pushing slightly on the stick, or that the tailplane is not

balanced out properly.



About the latter: I disconnected everything from the tailplane when

balancing it out. If you leave the stick connected, you won't get a

proper balance and the anti servo tab will not find its equilibrium in

line with the tailplane.



Next time we do this, I will vary the speed, trim for each speed, and

make a picture again. I would be really surprised if at any speed the

anti servo tab will not remain in its same relative position to the

tailplane. (Of course at every speed, the whole stack of tailplane plus

anti servo tab will rotate to a specific position... but with the anti

servo tab always in line with the tailplane. This is what you do if you

trim: lining the anti servo tab up with the tailplane in its new position).



Now, for your questions (although they don't matter):



 	  Quote: 	
		   - were you in stead-state constant-altitude cruise?


	


Yep. (We were in close formation so we wouldn't dare to fly anything

than a very stabilized attitude).



 	  Quote: 	
		   - where was your trim set at?


	


At 1/3 from the nose down limit.



 	  Quote: 	
		   - was your stick force = 0?


	


Of course 0.



 	  Quote: 	
		   - what was your cruise speed?


	


About 110 Knots.



 	  Quote: 	
		   - what was your weight and balance (with fuel at that point in time)?


	


Two adults, about 20Kg of bagage, and about 40 liters of fuel.



Frans

peterz(at)zutrasoft.com
Guest

Posted: Wed May 12, 2010 5:24 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

Hi Frans,

I understand your thesis (thanks again! .

Your thesis assumes that the tailplane is aerodynamically balanced wrt to the torque-tube position, and the only aerodynamic component which is stabilizing it and keeping it from flutter is the anti-servo tab.  

I question this, as the fulcrum is ahead of the center of the tailplane. Maybe my skepticism is unwarranted? Is the fulcrum in the center of the tailplane aerodynamically?  Without the anti-servo tab, would the tailplane flutter by design?  I doubt this is the case, as (I believe) the flettner strips were added to eliminate the 'dead zone' of the anti-servo tab (bringing it out of the boundary layer) to eliminate a trim-hunting issue, not flutter (someone with some historical knowledge please do chime in!).

I would expect/hope that the tailplane would remain aerodynamically stable without the anti-servo tab, and that the tab is there only to provide for progressive stick forces, and trim.

The "still curious",

 Pete 

On Wed, May 12, 2010 at 8:54 AM, Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)> wrote:

[quote] --> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>

 On 05/12/2010 01:03 PM, Peter Zutrauen wrote:

 > As the tailplane is a symmetrical airfoil,  my confused mind asserts

 > that in cruise (since the horizontal stab by definition must be

 > providing a downward force) your tailplane must have been at a negative

 > angle of attack, and since the combination anti-servo/trim tab was in a

 > neutral position then I would have expected a steady stick force would

 > have needed to be applied....

This is an *anti servo trim tab*, if it is not in line with the

 tailplane, it puts a force on the tailplane so that the tailplane

 rotates until it is in line with the anti servo trim tab again.

 You can easily see what I mean by exercising the trim in whatever

 position, and then carefully with your hands on the anti servo tab, try

 to push it in line with the tailplane again. You will see that the

 tailplane rotates during this process, and that you will always end up

 with the anti servo tab in line with the tailplane.

 This is true for *any* speed, *any* CG, etc, except when the pilot

 exercises some force on the stick. Any force on the stick gets into the

 equation and disturbes this balance.

 If you trim for a specific speed, all you do is put the stick in a

 specific position, and then with the trim button, line up the anti servo

 tab with the tailplane, to keep the tailplane at its new position. You

 will always end up with the anti servo tab in the same relative position

 of the tailplane.

 The real confusion is that there are people flying around with the anti

 servo tab not in line with the tailplane. This means they are either

 pulling or pushing slightly on the stick, or that the tailplane is not

 balanced out properly.

 About the latter: I disconnected everything from the tailplane when

 balancing it out. If you leave the stick connected, you won't get a

 proper balance and the anti servo tab will not find its equilibrium in

 line with the tailplane.

 Next time we do this, I will vary the speed, trim for each speed, and

 make a picture again. I would be really surprised if at any speed the

 anti servo tab will not remain in its same relative position to the

 tailplane. (Of course at every speed, the whole stack of tailplane plus

 anti servo tab will rotate to a specific position... but with the anti

 servo tab always in line with the tailplane. This is what you do if you

 trim: lining the anti servo tab up with the tailplane in its new position).

 Now, for your questions (although they don't matter):

 > - were you in stead-state constant-altitude cruise?

Yep. (We were in close formation so we wouldn't dare to fly anything

 than a very stabilized attitude).

 > - where was your trim set at?

At 1/3 from the nose down limit.

 > - was your stick force = 0?

Of course 0.

 > - what was your cruise speed?

About 110 Knots.

 > - what was your weight and balance (with fuel at that point in time)?

Two adults, about 20Kg of bagage, and about 40 liters of fuel.

 Frans

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 ="_blank">http://www.matronics.com/contribution

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 [b]

frans(at)privatepilots.nl
Guest

Posted: Wed May 12, 2010 5:53 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

On 05/12/2010 03:22 PM, Peter Zutrauen wrote:



 	  Quote: 	
		   Your thesis assumes that the tailplane is aerodynamically balanced wrt

 to the torque-tube position, and the only aerodynamic component which is

 stabilizing it and keeping it from flutter is the anti-servo tab. 


	


Stabilizing, but not necessarily keeping it from flutter. I think that

the mass balance weight is to keep it from flutter, just as with the

ailerons (that don't need to have a trim tab for that either).



 	  Quote: 	
		   I would expect/hope that the tailplane would remain aerodynamically

 stable without the anti-servo tab, and that the tab is there only to

 provide for progressive stick forces, and trim.


	


This is how it works I believe. At least is seems so on the PH-DIY. 



Frans

budyerly(at)msn.com
Guest

Posted: Wed May 12, 2010 6:45 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Good analysis Frans,

  

 If the tail plane is perfectly balanced and friction in the system nil, the  trim tab is centered.

 A too heavy counter weight is offset by the trailing edge of the tab  up.  A difference in flettner strips can cause the same.

  

 Flutter is dependent on the center of mass and the aerodynamic  center.  A horizontal control surface, mechanically balanced, with a  symmetrical airfoil surface with the aero center co-located with the center of  mass tends to stay neutrally stable.  Camber angle and or trim tabs change  that of course.

  

 When the center of mass is behind the the center of pressure, the trailing  edge goes down due to gravity, aerodynamic forces then try to lift the trailing  edge and in some cases overshoot the center line, so gravity and the aero forces  push the TE down, then it overshoots again and flutter occurs.  This is  especially a concern of a cambered aileron not mass balanced.

  

 I don't have time to go into the drawings, but a symmetrical  airfoil  contributes no moment to its normal force at low angles.  That is, if it is  perfectly balanced at its aerodynamic center, it will stay at its angle of  attack unless acted on mechanically and requires no force (beyond mechanical  friction in the mechanism) to move it. It will, by previous statement, also  apply no counter force when moved (so no pilot feel).  This is why we have  the anti servo tab, to create feedback to the pilot.  It also cleverly  applies trim.

   

 If the flettner strips are not perfect, and or the mass balance is slightly  off, your trim tab will show the effect of that.  The asymmetric flettner  strips of course act as a flap and become not an anti-servo tab, but a servo tab  which drives the trim tab, which drives the tail.

  



 As for the unbalanced anti-servo tab.  The tab itself does not  contribute to flutter if it is fixed.  If the tab  is loose, the tail plane bushings or trim bushings are missing, loose, damaged  or not installed, flutter will occur.   This  is why, I am such a zealot about stabilators, loose pins, and bearings.  I  would even prefer to try to mechanically balance the trim tab for the guy who  mistakenly fails to hook up the trim tab pins to the trim bar.

  

 Hope that doesn't add to the confusion Pete.

  

 Bud Yerly

 Tech Support

  

  

   

 [quote]   ---

grahamsingleton(at)btinte
Guest

Posted: Wed May 12, 2010 7:03 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

Pete

You are right about the flettner strips, they bite through the boundary layer and stop trim hunting hunting. The mass balance is there to balance the weight of the elevator.

Graham

From: Peter Zutrauen <peterz(at)zutrasoft.com>

To: europa-list(at)matronics.com

Sent: Wednesday, 12 May, 2010 14:22:36

Subject: Re: Re: Effects of Flaps and Ailerons on Pitch  Trim

Hi Frans,

I understand your thesis (thanks again! .

Your thesis assumes that the tailplane is aerodynamically balanced wrt to the torque-tube position, and the only aerodynamic component which is stabilizing it and keeping it from flutter is the anti-servo tab.  

I question this, as the fulcrum is ahead of the center of the tailplane. Maybe my skepticism is unwarranted? Is the fulcrum in the center of the tailplane aerodynamically?  Without the anti-servo tab, would the tailplane flutter by design?  I doubt this is the case, as (I believe) the flettner strips were added to eliminate the 'dead zone' of the anti-servo tab (bringing it out of the boundary layer) to eliminate a trim-hunting issue, not flutter (someone with some historical knowledge please do chime in!).

I would expect/hope that the tailplane would remain aerodynamically stable without the anti-servo tab, and that the tab is there only to provide for progressive stick forces, and trim.

The "still curious",

 Pete 

On Wed, May 12, 2010 at 8:54 AM, Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)> wrote:

[quote] --> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>

 On 05/12/2010 01:03 PM, Peter Zutrauen wrote:

 > As the tailplane is a symmetrical airfoil,  my confused mind asserts

 > that in cruise (since the horizontal stab by definition must be

 > providing a downward force) your tailplane must have been at a negative

 > angle of attack, and since the combination anti-servo/trim tab was in a

 > neutral position then I would have expected a steady stick force would

 > have needed to be applied....

This is an *anti servo trim tab*, if it is not in line with the

 tailplane, it puts a force on the tailplane so that the tailplane

 rotates until it is in line with the anti servo trim tab again.

 You can easily see what I mean by exercising the trim in whatever

 position, and then carefully with your hands on the anti servo tab, try

 to push it in line with the tailplane again. You will see that the

 tailplane rotates during this process, and that you will always end up

 with the anti servo tab in line with the tailplane.

 This is true for *any* speed, *any* CG, etc, except when the pilot

 exercises some force on the stick. Any force on the stick gets into the

 equation and disturbes this balance.

 If you trim for a specific speed, all you do is put the stick in a

 specific position, and then with the trim button, line up the anti servo

 tab with the tailplane, to keep the tailplane at its new position. You

 will always end up with the anti servo tab in the same relative position

 of the tailplane.

 The real confusion is that there are people flying around with the anti

 servo tab not in line with the tailplane. This means they are either

 pulling or pushing slightly on the stick, or that the tailplane is not

 balanced out properly.

 About the latter: I disconnected everything from the tailplane when

 balancing it out. If you leave the stick connected, you won't get a

 proper balance and the anti servo tab will not find its equilibrium in

 line with the tailplane.

 Next time we do this, I will vary the speed, trim for each speed, and

 make a picture again. I would be really surprised if at any speed the

 anti servo tab will not remain in its same relative position to the

 tailplane. (Of course at every speed, the whole stack of tailplane plus

 anti servo tab will rotate to a specific position... but with the anti

 servo tab always in line with the tailplane. This is what you do if you

 trim: lining the anti servo tab up with the tailplane in its new position).

 Now, for your questions (although they don't matter):

 > - were you in stead-state constant-altitude cruise?

Yep. (We were in close formation so we wouldn't dare to fly anything

 than a very stabilized attitude).

 > - where was your trim set at?

At 1/3 from the nose down limit.

 > - was your stick force = 0?

Of course 0.

 > - what was your cruise speed?

About 110 Knots.

 > - what was your weight and balance (with fuel at that point in time)?

Two adults, about 20Kg of bagage, and about 40 liters of fuel.

 Frans

 ===========

  target="_blank">http://www.matronics.com/Navigator?Europa-List

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ===========

 http://www.matronics.com/Navigator?Europa-Listhttp://=======================

[b]

peterz(at)zutrasoft.com
Guest

Posted: Wed May 12, 2010 7:54 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

Thanks to both Frans & Bud for the detailed explanations!



Coo!l .. it's all so clear to me now 



My build goal with then to have a perfectly flettner'd tab to emulate Frans's beautiful workmanship.

 

Cheers & thanks again!

Pete 

A239



On Wed, May 12, 2010 at 10:35 AM, Bud Yerly <budyerly(at)msn.com (budyerly(at)msn.com)> wrote:

 [quote]         Good analysis Frans,

  

 If the tail plane is perfectly balanced and friction in the system nil, the  trim tab is centered.

 A too heavy counter weight is offset by the trailing edge of the tab  up.  A difference in flettner strips can cause the same.

  

 Flutter is dependent on the center of mass and the aerodynamic  center.  A horizontal control surface, mechanically balanced, with a  symmetrical airfoil surface with the aero center co-located with the center of  mass tends to stay neutrally stable.  Camber angle and or trim tabs change  that of course.

  

 When the center of mass is behind the the center of pressure, the trailing  edge goes down due to gravity, aerodynamic forces then try to lift the trailing  edge and in some cases overshoot the center line, so gravity and the aero forces  push the TE down, then it overshoots again and flutter occurs.  This is  especially a concern of a cambered aileron not mass balanced.

  

 I don't have time to go into the drawings, but a symmetrical  airfoil  contributes no moment to its normal force at low angles.  That is, if it is  perfectly balanced at its aerodynamic center, it will stay at its angle of  attack unless acted on mechanically and requires no force (beyond mechanical  friction in the mechanism) to move it. It will, by previous statement, also  apply no counter force when moved (so no pilot feel).  This is why we have  the anti servo tab, to create feedback to the pilot.  It also cleverly  applies trim.

   

 If the flettner strips are not perfect, and or the mass balance is slightly  off, your trim tab will show the effect of that.  The asymmetric flettner  strips of course act as a flap and become not an anti-servo tab, but a servo tab  which drives the trim tab, which drives the tail.

  



 As for the unbalanced anti-servo tab.  The tab itself does not  contribute to flutter if it is fixed.  If the tab  is loose, the tail plane bushings or trim bushings are missing, loose, damaged  or not installed, flutter will occur.   This  is why, I am such a zealot about stabilators, loose pins, and bearings.  I  would even prefer to try to mechanically balance the trim tab for the guy who  mistakenly fails to hook up the trim tab pins to the trim bar.

  

 Hope that doesn't add to the confusion Pete.

  

 Bud Yerly

 Tech Support

  

  

   

 [quote]   ---

raimo.toivio(at)rwm.fi
Guest

Posted: Wed May 12, 2010 7:56 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

 	  Quote: 	
		  >

 The real confusion is that there are people 

 flying around with the anti

 servo tab not in line with the tailplane. This 

 means they are either

 pulling or pushing slightly on the stick, or 

 that the tailplane is not

 balanced out properly.


	


Frans, take it again:



Balancing is nothing to do with that.

Balancing is to prevent possible flutter.



Only case when the trim tabs and the stabilator 

are in line is then, when they are in their 

neutral position.

That is if the plane is correctly build as per 

manual.

In that case only the plane is in its cleanest 

condition.

You are able to achieve that with a certain 

combination of weight, speed, CofG etc but that is 

a special case.



What faster we fly that more we get lift by wings.

That is why we have to push more or trim nose down 

= trim tabs move upp when flying faster.

The stabilators´ trailing edges move then down.

They cannot be in-lined any more.



Overall, tailplanes /stabilators are neutralized 

only when CofG = CofL (w zero stick forces).



If you have to declect tailplanes (and wanna 

neutralize stick forces) you have to trim trim 

tabs to other direction.

The aerodynamical forces /deflected trim tab are 

then equal with the aerodynamical forces 

/deflected tailplanes.

They are balancing then each others by 

aerodynamically.



They have to be un-lined normally, more or less!



If not I am a Donald Duck!



That is why we usually and almost always see them 

(trimtabs) in deflected position only.

I am sure you will confirm that when you get take 

more photos.



In your photo you were flying 110 knots, w/o stick 

forces, trim tabs and tailplanes in line:

congratulations, your plane is very economical 

with that speed because obviously tailplanes are 

in their neutral position and the plane is most 

streamlined.

Otherwise - your neutral is not exactly neutral.

I assume your fuelflowcomputer will confirm that.



If you wanna fly slower or faster (with same load 

and conditions) I am sure your tailplanes and trim 

tabs are not any more in line.



The stick forces in Europa are quite light around 

100 knots. Also the necessary movements to keep 

level flight are small.

I would like to say: almost invisible when looking 

photos!

Look at attached photo: I was flying around 120 

knots with one Dynamic WT9.

My trim tabs are slightly deflected upwards - so 

the stabilators have to be deflected downwards a 

little bit.

If flying faster - they have to be deflected even 

more of course.



The stabilators are very powerful - that is why 

they are near their neutral position almost 

always.

That is why also the trim tabs are *almost* 

in-line fith stabilators.



Notice - just almost. If you have trimmed, they 

are not exactly in-lined any more.



***

Concorde did this by pumping fuel into fin or out 

from there. The stabilators could be so almost 

always in their neutral position and the plane was 

very clean.

With Europa, we could have let is say 10 kilos of 

fuel inside the fin...



That was my thought only. No confusion at all. 

Just aerodynamic.



I am sure I will get a fast speed reply  



Raimo



Terveisin, Raimo Toivio



Europa XS Mono OH-XRT #417



37500 Lempäälä

FINLAND



p +358-3-3753 777

f  +358-3-3753 100



toivio(at)fly.to

www.rwm.fi

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Viewed:

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frans(at)privatepilots.nl
Guest

Posted: Wed May 12, 2010 11:44 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

On 05/12/2010 05:17 PM, Donald Duck wrote:



 	  Quote: 	
		   What faster we fly that more we get lift by wings.

 That is why we have to push more or trim nose down = trim tabs move upp

 when flying faster.

 The stabilators´ trailing edges move then down.


	


YES! And the story doesn't end here.

Now, before we go any further, print this out, and take it with you to

the hangar.



Are you there? Fine.

1) Put the trim in the middle, and line up the tailplane and anti servo

tab by rotating the tailplane. If done properly, the tailplane is in

about its "neutral" position when it lines up with the anti servo tab.

2) Now, trim the nose down with your trim button. Anti servo tabs moves

up (assuming you wired everything correctly).

3) Let's play aerodynamics. Your hand is the airstream. The anti servo

trim "sticks out" in the airstream. Push with your hand on the anti

servo tab to imitate the aerodynamic forces.

4) Now LOOK! The anti servo tab goes down. Due to some ingenious

mechanical linking the trailing edge of the tailplane also moves down

(this is why you trimmed the nose down after all).

But most important: The anti servo tab moves faster down than the

tailplane. While pushing the anti servo tab downward, it will at some

moment be in line with the tailplane. Stop when you reach that moment.

This is your newly trimmed out position!

5) Now stare at it for a while, and consider what you just did. Try it

the other way around.

6) Start wondering why the anti servo tab would remain sticking out in

the airstream by itself while nobody is keeping it there. Also try

moving the trailing edge of the tailplane down without the anti servo

tab moving twice as fast downwards as well. It can't be done!

7) Congratulations! You just discovered that an anti servo tab is not a

regular trim tab! A regular trim tab is held in a fixed position and has

no choice. An anti servo tab can move, seek the most convenient

position, and as a consequence take the tailplane with it.



 	  Quote: 	
		   They have to be un-lined normally, more or less!

 

 If not I am a Donald Duck!


	


Quack. 



 	  Quote: 	
		   That is why we usually and almost always see them (trimtabs) in

 deflected position only.

 I am sure you will confirm that when you get take more photos.


	


If the opportunity exists, I will show it to you so you can see it with

your own eyes.



Frans

frans(at)privatepilots.nl
Guest

Posted: Thu May 13, 2010 1:25 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

On 05/12/2010 09:25 PM, I wrote:



 	  Quote: 	
		   Now, before we go any further, print this out, and take it with you to

 the hangar.

 

 Are you there? Fine.


	


Someone pointed out to me that he found my post "condescending". I had

to look up what this word means, but it wasn't a good thing. Now I'm

very worried that more people considered my post with similar feelings.



As my previous attempts to explain how I think the anti servo tab works

failed, I thought that a "look and feel" experience would make clear

what I mean. The idea that someone would try this out and imagining the

light bulb going on, together with the comment that "I'm Donald Duck if

it works that way" from the previous poster, was to me an invitation to

put some humor into the description.



I should have known. The balance between a humoristic description or a

condescending description is very marginal, too marginal for a non

native English writer like me. And on top of that is humor culture bound

(On a Dutch forum this post would have provoked a few ROFL smileys and

nobody would have taken offence, as we tend to be a little less formal

and polite than some other cultures).



So, I want to apologize to anyone who felt offended by my post, or

considered it "condescending". It really was not meant that way.



Frans

paul.the.aviator(at)gmail
Guest

Posted: Thu May 13, 2010 4:18 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

Frans, 



I certainly didn't perceive that from your descriptions. Your English grammar is impeccable, particularly so given that it is your second language. Perhaps the individual who took offense could give that some consideration.  I wonder how many languages he speaks ?

 

Paul



do not archive

  [quote][b]

kevann(at)gotsky.com
Guest

Posted: Thu May 13, 2010 4:47 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

Paul,  Your English grammar ain't bad (for an  Aussie).

 This yank pretty much got the sense of humor, and  even better, I think I gained a better understanding of how our tailplanes  work.

 I looked at in flight photos of N211KA and at about  120knots the tabs indeed are even with the TP.

 Thanks Franz,

 Kevin

 [quote] [b]

peterz(at)zutrasoft.com
Guest

Posted: Thu May 13, 2010 5:13 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

On Thu, May 13, 2010 at 5:24 AM, Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>  wrote:

--> Europa-List message posted by: Frans Veldman <frans(at)privatepilots.nl (frans(at)privatepilots.nl)>

 



"As my previous attempts to explain how I think the anti servo tab works

 failed, I thought that a "look and feel" experience would make clear

 what I mean."

The confusion around this topic (thus your "failure"  may be (at least it was in my case   ) that one has to accept the fact that the design's torque tube placement results in a (symmetrical airfoil) tailplane is *aerodynamically balanced*  for Frans'  functional description to make sense.  ie- no matter what the steady-state angle of incidence is of the tailplane, there are no resultant stick forces which need to be zero'd out by a portruding trim-tab ( which is the anti-servo tab in this case).

 

This was a very hard sell for myself. I had always assumed that that the tailplane's torque-tube location was slightly forward of the aerodynamic balance point, to make sure that the tailplane would always aerodynamically  "trail"  and thus be inherently stable (since it is mass-balanced). My rational was that if the design was perfectly aerodynamically balanced about the torquetube, and a builder had somehow managed to move the fulcrum slightly rearward of the aerodynamic balance point (build tolerances?), then the tailplane would be inherently unstable and that would be a disaster waiting to happen (in that case, once the tailplane is moved slightly producing an AOA ><0,  positive feedback would quickly take hold and slam it to the stop).

 

So, if one were to go down the same **incorrect** thought path as myself (the trailing tailplane idea), then indeed the anti-servo tab would need to remain deflected out in the airflow to keep any AOA other than zero (and also performing the function of a flap? .. this visualization still makes my head hurt).  

 

So, since we are dealing with an "approaching perfect" design (an aerodynamically balanced tailplane), Frans'  assertion of the anti-servo tab always nulling itself out is correct (boundary layer effects being ignored/taken care of by the flettner strips), regardless of  airspeed, COG, airplane AOA etc.

 

I'm still curious how close to perfectly aerodynamically balanced the tailplane design is. Don Dykins sure was a clever fellow.



Cheers,

Pete

A239

  [quote][b]

frans(at)privatepilots.nl
Guest

Posted: Thu May 13, 2010 6:04 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

On 05/13/2010 03:12 PM, Peter Zutrauen wrote:



 	  Quote: 	
		   The confusion around this topic (thus your "failure"  may be (/at

 least it was in my case/   ) that one has to accept the fact that the

 design's torque tube placement results in a (symmetrical airfoil)

 tailplane is *aerodynamically balanced*  for Frans'  functional

 description to make sense.  ie- no matter what the steady-state angle of

 incidence is of the tailplane, there are no resultant stick forces which

 need to be zero'd out by a portruding trim-tab ( which is the anti-servo

 tab in this case).


	


Ah, OK, now I see your point.

I thought that this aerodynamically balance was the major "selling

point" of the tailplane, and hence common knownledge amongst builders. I

recall having read somewhere that the whole purpose of the mass balance

arm is to cancel out the weight offset, which is a *result* of having

the torque tube in the aerodynamic center, rather than in the weight center.



I have to admit that it took me a while too before I grabbed the

concept. The whole arrangement with the anti servo tabs which double

duty as trim tabs at the same time is indeed a genious concept. If the

anti servo tabs are always in line with the tailplane, there is never a

drag penalty, regardless of trim setting. This is just one of the things

that make the Europa a relatively fast airplane.



Then you can maybe understand that I found it rather shocking to read

that "all Europa's are flying with the trim tabs deflecting upwards"...

as this would defeat the whole purpose of the ingenious anti servo tab

and all flying tailplane. I was prepared to find a way to fix this

problem once I would reach the flying stage... until I discovered to my

delight that the PH-DIY doesn't suffer from this problem at all.



I'm still curious however why some Europa's suffer this problem.



 	  Quote: 	
		   I'm still curious how close to perfectly aerodynamically balanced the

 tailplane design is. Don Dykins sure was a clever fellow.


	


Was Don Dykins responsible for the tailplane too? He was indeed a clever

fellow.



Frans

loboloda(at)execulink.com
Guest

Posted: Thu May 13, 2010 12:28 pm Post subject: Effects of Flaps and Ailerons on Pitch Trim

Kevin,

I seem to remember being reprimanded by Paul for calling him an Aussie, although it was more or less the right part of the world.



Dave



do not archive 

On 13-May-10, at 8:46 AM, Kevin Klinefelter wrote:

[quote]  Paul,  Your English grammar ain't bad (for an Aussie).

 This yank pretty much got the sense of humor, and even better, I think I gained a better understanding of how our tailplanes work.

 I looked at in flight photos of N211KA and at about 120knots the tabs indeed are even with the TP.

 Thanks Franz,

 Kevin

  	  Quote: 	
		   

href="http://www.matronics.com/Navigator?Europa-List">http://www.matronics.com/Navigator?Europa-List

href="http://forums.matronics.com">http://forums.matronics.com

href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	
[b]

paul.the.aviator(at)gmail
Guest

Posted: Thu May 13, 2010 1:06 pm Post subject: Effects of Flaps and Ailerons on Pitch Trim

Heck no... I only get bent out of shape for being mistaken for a Brit.... )



do not archive



On Thu, May 13, 2010 at 3:38 PM, david miller <loboloda(at)execulink.com (loboloda(at)execulink.com)> wrote:

 [quote]Kevin,



I seem to remember being reprimanded by Paul for calling him an Aussie, although it was more or less the right part of the world.

 



Dave

do not archive 

On 13-May-10, at 8:46 AM, Kevin Klinefelter wrote:



 	  Quote: 	
		    Paul,  Your English grammar ain't bad (for an Aussie).

  This yank pretty much got the sense of humor, and even better, I think I gained a better understanding of how our tailplanes work.

 I looked at in flight photos of N211KA and at about 120knots the tabs indeed are even with the TP.

  Thanks Franz,

 Kevin



	


[b]

rparigoris

Joined: 24 Nov 2009
Posts: 792

Posted: Thu May 13, 2010 1:32 pm Post subject: Effects of Flaps and Ailerons on Pitch Trim

Hi Paul"I only get bent out of shape for being mistaken for a Brit...."That's good to know in case I thought you were from NZ!Ron Parigoris Do Not archive   [quote][b]

grahamsingleton(at)btinte
Guest

Posted: Fri May 14, 2010 2:40 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

Don was responsible for all the flying surfaces.

I wonder if some Europas are not correctly mass balanced, it's not easy if there is any stiffness in the pitch control (which I have seen too often)



Graham



From: Frans Veldman <frans(at)privatepilots.nl>

To: europa-list



I'm still curious however why some Europa's suffer this problem.



 	  Quote: 	
		   I'm still curious how close to perfectly aerodynamically balanced the

 tailplane design is. Don Dykins sure was a  clever fellow.


	


Was Don Dykins responsible for the tailplane too? Heics.com/Navigator?Europa-List" target="_blank">http://www.matronics.com/N=               - MATRONICS WEB FORUMS=   -->

raimo.toivio(at)rwm.fi
Guest

Posted: Fri May 14, 2010 9:23 am Post subject: Effects of Flaps and Ailerons on Pitch Trim

Frans



and all of you:



I woke upp last night and got a light like a 

lightning to my poor salesman brains.

That was well before your message below.

I have not visited my Europa and that is not 

necessary because of this question.



You - Frans - are absolutely right!



My mistake:



I thought Europa´s tailplanes are like any other 

ordinary elevators.

Because it´s natur to be all flying I understood 

it is very light to operate but I did not 

understand the real meaning of "aerodynamically 

balanced".

I have always thought as follows: fore of the 

torque tube there is about 1/3 of tailplanes and 

behind there are 2/3 of tailplanes.

That is why I have assumed there are aerodynamical 

forces but only let is say 2/3 - 1/3 = 1/3 when 

compared to "normal" solution like Cessna´s 

elevator.



Finally now I understand the name of the game: 

without the antiservo function pitch would be 

totally w/o forces in the stick!

Awful!

When trimming that means we are in fact in-lining 

tailplanes with trimtabs to a certain desired 

position!



I got some messages which were supporting my idea 

and for example Mr X from Z wrote



"Now lets increase our speed to say 140 kts in 

straight and level flight

without trimming . . . . . you and I both know 

that we will require a

forward pressure on the stick which of course is a 

pain so we need to trim

the tailplane so that aerodynamic forces are 

substitued for our mussle

power.  Now if Frans is correct, the trim tab will 

once again be aligned

with the trailing edge of the tailplane so what 

the hell is providing the

necessary force to hold the tailplane in the new 

position?  The tab simply

MUST be displaced to provide the necessary force 

to my way of thinking."



That was exactly what I thought also.



And answer is: there is NO necessary need for any 

force to hold the tailplane in the new position 

because it is happy with ANY position.

That is why they (tailplanes and trim tabs) are 

always in-lined when trimmed properly.

When trimming - you are in fact cleaning the 

entire system!!!



The most genious part: what is keeping it there in 

the desired position?

If the tailplanes try to move upp or down, trim 

tabs move automatically even more to same 

direction and that is why the are fixed just that 

position where pilot has trimmed them.

And they stay here until new trimming or pilot 

force via stick.



That is why I feel a bit or more frightened also: 

without antiservo function there would be not att 

all any idea what is the position of the 

tailplanes!!!

No stick forces at all!!!



Before flight I have always checked my tabs but 

from this point I will do it very carefully!!!

Without them or that function I assume Europa will 

be a flying coffin.

Until now I am happy I did that mod (mandatory in 

England) which enhanced trim tabs´s pins years 

ago!!!

I remember I almost cancelled because I was 

tempted to imagine those trim tabs are nice but 

not totally necessary for safety!!!



One interesting point also: obviously all the 

tailplanes which have been built perfectly, are 

perfectly also aerodynamically balanced.

Like Frans´s Europa´s tailplanes.

Then and only then the trim tabs are always lined 

with tailplanes when properly trimmed!!!



My Europa and many other Europa´s trim tabs are 

(when watching photos) slightly deflected when 

cruising and the plane is trimmed.

That means those tailplanes are not perfectly 

built = they are not perfectly aerodynamically 

balanced.

Obviously it is hard to produce perfect shaped 

tailplanes when making foam tailplanes like mine 

but next generation tailplanes without foam 

structure are maybe "automatically" perfect.



Frans, thanks for patience.

Frans, thanks for educating me and some other 

persons on the globe.

Frans, thanks for you because now I understand a 

bit more my plane and respect it much more.



I did not feel at all



"Someone pointed out to me that he found my post 

"condescending". "



They say some Dutch people are a bit arrogant but 

you - Frans - are not.  Just brilliant. I am 

pround we are in the same list and fly same plane.



***



OK. I am a Donald Duck. Kwaak kwaak kwaa.

But I am a happy duck. That is because



- my nephews are talent.

- I have a nice career in a fat factory.

- my uncle (Scrooge) have some nice jets, bush 

planes, DC-3 and many others and I am able to fly 

them all, also IFR in Alaska through snow storms.

- my uncle is the richiest duck in the world and 

some day I will be his heir.

- my girlfriend Iines Duck is very atractive.

- my daughters love Donald D.



Frans - next time I will consider a bit more 

before I think you are wrong.

You are wrong probably very seldom, I assume.



Would be nice to meet you in Texel next autumn.



I give you some extra present: have you earlier 

seen a Duck on the wing behind a running star 

engine?



Raimo (cheekbones totally red) aka DD



Terveisin, Raimo Toivio



Europa XS Mono OH-XRT #417



37500 Lempäälä



p +358-3-3753 777

f +358-3-3753 100



toivio(at)fly.to

www.rwm.fi





--------------------------------------------------

From: "Frans Veldman" <frans(at)privatepilots.nl>

Sent: Wednesday, May 12, 2010 10:25 PM

To: <europa-list(at)matronics.com>

Subject: Re: Re: Effects of Flaps and 

Ailerons on Pitch Trim



 	  Quote: 	
		   

 <frans(at)privatepilots.nl>



 On 05/12/2010 05:17 PM, Donald Duck wrote:



> What faster we fly that more we get lift by 

> wings.

> That is why we have to push more or trim nose 

> down = trim tabs move upp

> when flying faster.

> The stabilators´ trailing edges move then down.



 YES! And the story doesn't end here.

 Now, before we go any further, print this out, 

 and take it with you to

 the hangar.



 Are you there? Fine.

 1) Put the trim in the middle, and line up the 

 tailplane and anti servo

 tab by rotating the tailplane. If done properly, 

 the tailplane is in

 about its "neutral" position when it lines up 

 with the anti servo tab.

 2) Now, trim the nose down with your trim 

 button. Anti servo tabs moves

 up (assuming you wired everything correctly).

 3) Let's play aerodynamics. Your hand is the 

 airstream. The anti servo

 trim "sticks out" in the airstream. Push with 

 your hand on the anti

 servo tab to imitate the aerodynamic forces.

 4) Now LOOK! The anti servo tab goes down. Due 

 to some ingenious

 mechanical linking the trailing edge of the 

 tailplane also moves down

 (this is why you trimmed the nose down after 

 all).

 But most important: The anti servo tab moves 

 faster down than the

 tailplane. While pushing the anti servo tab 

 downward, it will at some

 moment be in line with the tailplane. Stop when 

 you reach that moment.

 This is your newly trimmed out position!

 5) Now stare at it for a while, and consider 

 what you just did. Try it

 the other way around.

 6) Start wondering why the anti servo tab would 

 remain sticking out in

 the airstream by itself while nobody is keeping 

 it there. Also try

 moving the trailing edge of the tailplane down 

 without the anti servo

 tab moving twice as fast downwards as well. It 

 can't be done!

 7) Congratulations! You just discovered that an 

 anti servo tab is not a

 regular trim tab! A regular trim tab is held in 

 a fixed position and has

 no choice. An anti servo tab can move, seek the 

 most convenient

 position, and as a consequence take the 

 tailplane with it.



> They have to be un-lined normally, more or 

> less!

>

> If not I am a Donald Duck!



 Quack. 



> That is why we usually and almost always see 

> them (trimtabs) in

> deflected position only.

> I am sure you will confirm that when you get 

> take more photos.



 If the opportunity exists, I will show it to you 

 so you can see it with

 your own eyes.



 Frans

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