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Maximum flap extension?

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frans(at)paardnatuurlijk.
Guest

Posted: Mon Aug 04, 2008 2:24 pm Post subject: Maximum flap extension?

Hi,



I just finished installing the flap drive mechanism. My assumption was that the strap on the outboard flap hinge determined the maximum flap extension, i.e. 30 degrees. So when I installed the flap drive tube, I made slots in the fuselage to accommodate the entire range for the flaps.



To my dismay, after installation of the actuator, the flaps only use 2/3th of the available range. The actuator reaches its limit far before the strap of the outboard flap hinge reaches its limit.



To be sure, I measured the difference in angle of the flap, between fully retracted and "fully" extended. This is only 24 degrees! I confirmed this with a digital gauge. Now I don't see how I can have done something wrong with this, as long as you don't cut the hinges or reshape the flap drive tube, you can't alter the maximum flap extension. 



As a further test, I temporarily attached the Europa flap indicator decal on the flap and wing, and to my surprise this decal tells me that the flap, fully extended, reaches 30 degrees...



Several questions cross my mind:



1) Is my method to measure the maximum flap extension correct? Does "30 degrees flaps" actually mean that the flaps have rotated 30 degrees?



2) Has anyone else actually measured the maximum flap extension? The build manual doesn't tell you to measure it, but I suspect I'm not the only one who wants to measure everything related to the controls. Or does everyone else just trust the Europa flap indicator decal?



3) Why do I only get 24 degrees of flap extension? Maybe on the mono wheel it is reaching 30 degrees, but on the tri-gear the electrical actuator is just too short so it limits the flaps to 24 degrees?



4) If I drill another hole in the lugs of the flap drive tube, closer to the rotation center (i.e. truncating the lever action of the lugs) I will get more flap travel (at the cost of a slight reduction in flap drive power). Anyone tried this? It seems to me a safe way to fix this problem.



5) What is actually the maximum flap extension one can obtain? I suspect that it is possible to actually get more than 30 degrees if the full travel allowed by the outboard hinges is fully used. (I'm flying a Cessna with 40 degrees flaps, and I really love these 40 degrees flaps). Anyone tried/implemented this?

 

Thanks in advance for any answers.



Frans

Visit -  www.EuropaOwners.org

christoph.both(at)acadiau
Guest

Posted: Mon Aug 04, 2008 5:24 pm Post subject: Maximum flap extension?

Hi Frans:

I have a Classic TRI conversion. I also ended up with less flap travel, measured with a digital level affixed to the flap top surface. I have max 26 degrees. I do trust my digital level and so I phoned the factory. They said for  TRI 26 degrees would be just fine.

I still feel 30 degree would be better but I guess the flight test will show.

I would be cautious of re-drilling the lug, effectively moving the pushrod more to the centre. This is why: you definitively need to have sufficient material around the new lug hole (I consider a full diameter of the bore an absolute minimum). But moving the new bore this much inboard while keeping material standards and building practices up will most certainly be more drastic than what you want to achieve. In brief, you will get most likely more than 30 degrees - NO GOOD.

Call the factory and ask what they suggest. I can see a solution by welding on an additional layer of same steel to the lug and then re-drill to the correct hole location (after lots of experimentation with cardboard templates etc. !). This will definitively fix it.

Christoph Both

#223 Wolfville Nova Scotia



________________________________



From: owner-europa-list-server(at)matronics.com on behalf of Frans Veldman

Sent: Mon 8/4/2008 7:22 PM

To: europa-list(at)matronics.com

Subject: Maximum flap extension?






Hi,



I just finished installing the flap drive mechanism. My assumption was that the strap on the outboard flap hinge determined the maximum flap extension, i.e. 30 degrees. So when I installed the flap drive tube, I made slots in the fuselage to accommodate the entire range for the flaps.



To my dismay, after installation of the actuator, the flaps only use 2/3th of the available range. The actuator reaches its limit far before the strap of the outboard flap hinge reaches its limit.



To be sure, I measured the difference in angle of the flap, between fully retracted and "fully" extended. This is only 24 degrees! I confirmed this with a digital gauge. Now I don't see how I can have done something wrong with this, as long as you don't cut the hinges or reshape the flap drive tube, you can't alter the maximum flap extension.



As a further test, I temporarily attached the Europa flap indicator decal on the flap and wing, and to my surprise this decal tells me that the flap, fully extended, reaches 30 degrees...



Several questions cross my mind:



1) Is my method to measure the maximum flap extension correct? Does "30 degrees flaps" actually mean that the flaps have rotated 30 degrees?



2) Has anyone else actually measured the maximum flap extension? The build manual doesn't tell you to measure it, but I suspect I'm not the only one who wants to measure everything related to the controls. Or does everyone else just trust the Europa flap indicator decal?



3) Why do I only get 24 degrees of flap extension? Maybe on the mono wheel it is reaching 30 degrees, but on the tri-gear the electrical actuator is just too short so it limits the flaps to 24 degrees?



4) If I drill another hole in the lugs of the flap drive tube, closer to the rotation center (i.e. truncating the lever action of the lugs) I will get more flap travel (at the cost of a slight reduction in flap drive power). Anyone tried this? It seems to me a safe way to fix this problem.



5) What is actually the maximum flap extension one can obtain? I suspect that it is possible to actually get more than 30 degrees if the full travel allowed by the outboard hinges is fully used. (I'm flying a Cessna with 40 degrees flaps, and I really love these 40 degrees flaps). Anyone tried/implemented this?



Thanks in advance for any answers.



Frans

Visit -  www.EuropaOwners.org

davidjoyce(at)doctors.org
Guest

Posted: Tue Aug 05, 2008 12:22 am Post subject: Maximum flap extension?

Frans, For the XS mono kit 402 the manual says the aim is to get the flaps 

to extend to 26-27 degrees. The supplied Europa final inspection sheet 

stipulates minimum 25 and max 27 degrees. Hope this helps. regards, David 

Joyce

---

g-iani(at)ntlworld.com
Guest

Posted: Tue Aug 05, 2008 1:07 am Post subject: Maximum flap extension?

As David says it should be 26-27 degrees.  Mine ended up dead on 27.



Ian Rickard G-IANI XS Trigear, 200 hours

Europa Club Mods Rep (Trigear)

e-mail mods(at)europaclub.org.uk   

   or direct g-iani(at)ntlworld.com

--

grahamsingleton(at)btinte
Guest

Posted: Tue Aug 05, 2008 1:28 am Post subject: Maximum flap extension?

Europa factory tried 30degrees on a mono wheel and found that the 

airplane would lift off too early, (ground effect) so you end up flying 

without aileron control. That's why 27 is considered the max deflection.

Graham



David Joyce wrote:

 	  Quote: 	
		   

 <davidjoyce(at)doctors.org.uk>



 Frans, For the XS mono kit 402 the manual says the aim is to get the 

 flaps to extend to 26-27 degrees. The supplied Europa final inspection 

 sheet stipulates minimum 25 and max 27 degrees. Hope this helps. 

 regards, David Joyce

> 

> <frans(at)paardnatuurlijk.nl>

>

> Hi,

>

> I just finished installing the flap drive mechanism. My assumption 

> was that the strap on the outboard flap hinge determined the maximum 

> flap extension, i.e. 30 degrees. So when I installed the flap drive 

> tube, I made slots in the fuselage to accommodate the entire range 

> for the flaps.

ami(at)mcfadyean.freeserv
Guest

Posted: Tue Aug 05, 2008 10:52 am Post subject: Maximum flap extension?

Or not.



The mono is limited to 27 degrees of flap extension in order to prevent is

taking off before the controls are effective. Which confirms that more 27

degrees of flap extension is effective!



There is at least one trigear flying with more than the standard flap

movement (30+); this was achieved by a longer-stroke servo.



Theoretically, fowler flaps don't like more than about 30 degrees, although

G-YURO tested to more than this.



The non Mono Europa, which has its own speed break (the monowheel swing arm)

could certainly do with more drag at full flap. And sideslipping has little

effect!



Duncan McF.

---

davidjoyce(at)doctors.org
Guest

Posted: Wed Aug 06, 2008 12:16 am Post subject: Maximum flap extension?

There is the consideration that increasing the flap extension beyond its 

stated limit might push the structural limits of the flaps. Don Dykin's 

booklet on the aerodynamics of the Europa says that at max flap speed the 

flaps support about half of the plane's weight. Could an extra 3 degrees and 

a corresponding change of the angle of the flap lift force be the straw that 

did for that particular camel?  Regards, David Joyce, G-XSDJ

---

rparigor(at)suffolk.lib.n
Guest

Posted: Wed Aug 06, 2008 8:46 am Post subject: Maximum flap extension?

Hi David



"> There is the consideration that increasing the flap extension beyond

its 

 	  Quote: 	
		   stated limit might push the structural limits of the flaps. Don Dykin's 

 booklet on the aerodynamics of the Europa says that at max flap speed the 

 flaps support about half of the plane's weight. Could an extra 3 degrees and 

 a corresponding change of the angle of the flap lift force be the straw that 

 did for that particular camel?"


	


No matter what the absolute answer is, best to keep maximum flap extension

speed as published.



That said my partner Wayne built a model of the Europa XS in X-Plane. One

mode is you can display dynamic arrows of stress. You can not believe how

rapid the stresses on the outboard section of the wing grow when you

exceed maximum flap extension speed! It begins that with full flaps the

tip of the wing is lifting a little, then with increased speed the inboard

section of the wing is lifting so much it requires that you lower the

nose, then the outboard section of the wing now is creating negative lift

and then if you increase speed further, the stresses look downright scary!

Increasing flap angle would no doubt place greater loads as stated above. 



Ron Parigoris

grahamsingleton(at)btinte
Guest

Posted: Wed Aug 06, 2008 9:34 am Post subject: Maximum flap extension?

Ron

Thanks for the X-Plane data Ron, I must install my copy and learn to use 

it! Steep learning curve I fear 

increased flap deflection would therefore reduce the flap limiting speed 

too.

Graham



rparigor(at)suffolk.lib.ny.us wrote:

 	  Quote: 	
		   

   

 No matter what the absolute answer is, best to keep maximum flap extension

 speed as published.



 That said my partner Wayne built a model of the Europa XS in X-Plane. One

 mode is you can display dynamic arrows of stress. You can not believe how

 rapid the stresses on the outboard section of the wing grow when you

 exceed maximum flap extension speed! It begins that with full flaps the

 tip of the wing is lifting a little, then with increased speed the inboard

 section of the wing is lifting so much it requires that you lower the

 nose, then the outboard section of the wing now is creating negative lift

 and then if you increase speed further, the stresses look downright scary!

 Increasing flap angle would no doubt place greater loads as stated above. 



 Ron Parigoris

ami(at)mcfadyean.freeserv
Guest

Posted: Wed Aug 06, 2008 2:47 pm Post subject: Maximum flap extension?

Would certainly need a reduction of flap limiting speed.

As aerodynamic loads vary as the square of velocity, a 10% increase in flap 

lift/drag load (for the sake of argument resulting from a 10% increase in 

flap angle) would reduce white-arc maximum speed by a factor equivalent to 

the inverse of the square root of 1.1. So 95 knts becomes 90 knts.

Presuming that the limiting speeds were not in the first place determined at 

the original angles used on the prototype.



Duncan McF

---

craigb(at)onthenet.com.au
Guest

Posted: Thu Aug 07, 2008 1:18 am Post subject: Maximum flap extension?

"That said my partner Wayne built a model of the Europa XS in X-Plane. One

mode is you can display dynamic arrows of stress. You can not believe how

rapid the stresses on the outboard section of the wing grow when you

exceed maximum flap extension speed! It begins that with full flaps the

tip of the wing is lifting a little, then with increased speed the inboard

section of the wing is lifting so much it requires that you lower the

nose, then the outboard section of the wing now is creating negative lift

and then if you increase speed further, the stresses look downright scary!"



I seem to recall a few incidents/accidents with high wing ultralights that

have the covered wings

and a main support brace about half way along the wing, where a reduction in

VNE was mandated.

They were getting into the same area as the simulations suggest here where

the outer half of the wing

was generating negative lift to such an extent it was breaking the back of

the wing with no warning. Knowing

that i wouldnt be messing with it unless you have a degree in engineering

and KNOW the loads are ok (maybe you do if so tinker away)

its not worth wrecking you plane over a few Knots of approach speed IMHO



craig



Do Not Archive

frans(at)paardnatuurlijk.
Guest

Posted: Fri Aug 08, 2008 3:27 am Post subject: Maximum flap extension?

It is nice to read all this information and opinions.



I believe the Europa was originally designed for 30 degrees flaps. It seems to me that you don't deliberately design for 27 degrees, but choose a common round number, like 30. Also the strap on the outboard hinge points into this direction.



As someone pointed out, after flight testing it appeared that 30 degrees caused the mono to fly off prematurely, so they limited the flaps to 27 degrees. It is unlikely that the flap structure has been weakened afterwards, so the flaps are most likely able to handle 30 degrees.



For the rest it is a matter of personal preference whether you take advantage of this information. 3 degrees may not be worth the trouble to fuss with, on the other hand some of us go through great extends for 3 knots more speed, or 3 kilo's less weight, etc. It is tempting to achieve the best figures possible, even if they are unlikely to make a noticeable difference in real life.



I agree that cranking out 40 degrees of flaps is not a good idea, the 40 degrees was only mentioned to point out that some airplanes have it and that it proves to be very useful. Basically you can't have too much flaps, especially not in a airplane that builds up speed very easily during a descent. In that respect, a maximum of 25 degrees of flaps is not ideal.



BTW, We don't necessarily have to think in the direction of "more" flaps, "less" flaps (negative) is also possible with a longer stroke. Some people played with the idea to implement a negative flap option, but so far nobody actually seems to have tried it. Otherwise I would love to hear about that too.



It would be nice if we could get to know what maximums the flap system could structurally deal with.



Frans

Visit -  www.EuropaOwners.org

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