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wing lift/drag pins
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grahamsingleton(at)btinte
Guest

Posted: Sun Jun 30, 2013 3:20 pm Post subject: wing lift/drag pins

Alan

the thing to remember is that sometime you will hit a sharp edge gust which will cause Hi AoA and

if you don't have provision for that load, ie pip pins through the rear lift pins your wings will clap, forwards.

It happened to a glider at high speed once over Europe, one of the early hot ships. The pilot couldn't understand why the wings were in front of him when they came off! Lots of the rest of us didn't understand for a while either. VECTORS!

Graham

        From: Alan Carter  <alancarteresq(at)onetel.net>

 To: europa-list(at)matronics.com 

 Sent: Monday, 1 July 2013, 0:10

 Subject: Re: wing lift/drag pins

  

 

--> Europa-List message posted by: "Alan Carter" <alancarteresq(at)onetel.net (alancarteresq(at)onetel.net)>



Hello Graham and Kingsley.

Well thank you both very much, Indeed the diagrams show a forward component, and it says the wings pull forward, and indeed the bracket has a pin through it which one would associate with pulling forward maybe.  , But i am still not convinced wish i was.

I guess you are all probably right , but i see the possibility of a forward 

pull at high angles of attack , but in normal flight i see the a  backward

component , this being most of the time in normal flight, so you have both forward and backward movements of the wing.

But i think you are looking at the lift envelope, so i still think the Total

of all the components is backward, Stall turn or Tail slip the 

exceptions.



I have this. It mentions Tensile, But it dose not really state the normal condition of this bar, well not to me,

This modification introduces a new wing rear-attachment pin with a longer threaded portion and a

Nyloc nut and load spreading washer added behind the inboard flap hinge-plate to react the tensile

load in the pin and so increase the tolerance to incorrectly constructed hard points. In addition,

a tie-bar is incorporated to efficiently react tensile loads between the wing rear attachments. The

tie-bar forms part of optional Mod 52, however, unless all the other features of Mod 52 are installed, 

no increase in maximum gross weight  will be permitted.



I asked a friend who was head of physics he said the same as me.

But We could both be wrong, At the moment my thoughts are mostly backwards but on High AA possible forward, but i am not sure.

I will follow this up and try to write to somebody Aerodynamics.

As i am really interested now. Maybe i will start with Europa them self, this is going to take me some time.

But i need to satisfy myself that my understanding is maybe wrong??.

  



Regards.

Alan





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=403661#403661



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Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Sun Jun 30, 2013 4:01 pm Post subject: Re: wing lift/drag pins

Hi Graham.

I understand a little in what you a saying.

In the tail slip the wing is falling backwards to normal  flight condition.

The pin would stop the wing from pulling out.



But in normal level flight i see this bar in compression.

At this moment in time, i just can not see how you would get a forward force.



I find Europa.s notes mentioning words like "tie bar",

but i find many of Europa,s notes not to clear as to exactly what the situation is.



I think this bar is say, in compression 90% of the time and 10% in tension some of the time, hence the pin. 

But what the hell do i know, but im not giving up yet.



Need a little micro transducer between the front wing root to see which the bios is.



Best Regards.

Alan

houlihan(at)blueyonder.co
Guest

Posted: Sun Jun 30, 2013 11:56 pm Post subject: wing lift/drag pins

Hi Alan.



A few comments, 

1, wings that have been demonstrated to fly OK for many thousands of hours do not usualy fail in normal flight , it should only happen in extreme circumstances so forget about your 1 "G" straight and level situation.

 



2, your comments about the WW2 bomber do not demonstrate failure due to aerodynamic loading., During the bomb release phase of flight it would be in 1"G" straight and level flight. the failure occurred because the fuselage holding the wings apart was removed allowing them to react as you describe.

 



3, there are lots of things in life I do not understand like high energy physics and brain surgery but when people who know about these things try and explain to me I try to listen and learn. you seem to have rejected all the explanations put forward by knowledgeable contributors to this forum. So when you find the answer from other sources  please let us know the outcome so that we can all learn something.

 



4, If a Cessna 150 was over stressed in a high "G" maneuver to the extent that the mainplanes failed they would also fold forwards and upwards probably outboard of the struts..

 



Tim



On 1 July 2013 01:01, Alan Carter <alancarteresq(at)onetel.net (alancarteresq(at)onetel.net)> wrote:

 [quote]--> Europa-List message posted by: "Alan Carter" <alancarteresq(at)onetel.net (alancarteresq(at)onetel.net)>

  

 Hi Graham.

 I understand a little in what you a saying.

 In the tail slip the wing is falling backwards to normal  flight condition.

 The pin would stop the wing from pulling out.

 

 But in normal level flight i see this bar in compression.

 At this moment in time, i just can not see how you would get a forward force.

 

 I find Europa.s notes mentioning words like "tie bar",

 but i find many of Europa,s notes not to clear as to exactly what the situation is.

 

 I think this bar is say, in compression 90% of the time and 10% in tension some of the time, hence the pin.

 But what the hell do i know, but im not giving up yet.

 

 Need a little micro transducer between the front wing root to see which the bios is.

 

 Best Regards.

 Alan

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=403665#403665

 

 

 

 

 

 

 

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 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

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

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 [b]

rogersheridan(at)gmail.co
Guest

Posted: Mon Jul 01, 2013 12:55 am Post subject: wing lift/drag pins

Surely in gliding flight the wings must be pulling the fuselage forwards..........otherwise you would stop!

On 1 Jul 2013, at 08:55, houlihan <houlihan(at)blueyonder.co.uk (houlihan(at)blueyonder.co.uk)> wrote:

[quote]Hi Alan.



A few comments, 

1, wings that have been demonstrated to fly OK for many thousands of hours do not usualy fail in normal flight , it should only happen in extreme circumstances so forget about your 1 "G" straight and level situation.

 



2, your comments about the WW2 bomber do not demonstrate failure due to aerodynamic loading., During the bomb release phase of flight it would be in 1"G" straight and level flight. the failure occurred because the fuselage holding the wings apart was removed allowing them to react as you describe.

 



3, there are lots of things in life I do not understand like high energy physics and brain surgery but when people who know about these things try and explain to me I try to listen and learn. you seem to have rejected all the explanations put forward by knowledgeable contributors to this forum. So when you find the answer from other sources  please let us know the outcome so that we can all learn something.

 



4, If a Cessna 150 was over stressed in a high "G" maneuver to the extent that the mainplanes failed they would also fold forwards and upwards probably outboard of the struts..

 



Tim



On 1 July 2013 01:01, Alan Carter <alancarteresq(at)onetel.net (alancarteresq(at)onetel.net)> wrote:

  	  Quote: 	
		  --> Europa-List message posted by: "Alan Carter" <alancarteresq(at)onetel.net (alancarteresq(at)onetel.net)>

  

 Hi Graham.

 I understand a little in what you a saying.

 In the tail slip the wing is falling backwards to normal  flight condition.

 The pin would stop the wing from pulling out.

 

 But in normal level flight i see this bar in compression.

 At this moment in time, i just can not see how you would get a forward force.

 

 I find Europa.s notes mentioning words like "tie bar",

 but i find many of Europa,s notes not to clear as to exactly what the situation is.

 

 I think this bar is say, in compression 90% of the time and 10% in tension some of the time, hence the pin.

 But what the hell do i know, but im not giving up yet.

 

 Need a little micro transducer between the front wing root to see which the bios is.

 

 Best Regards.

 Alan

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=403665#403665

 

 

 

 

 

 

 

 ===========

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

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

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

 ===========

 

 

 

 

	
[b]

Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Mon Jul 01, 2013 1:41 am Post subject: Re: wing lift/drag pins

Hi Bob.

Thats seem,s reasonable , and a windmill goes round,

So dose that mean a wing in flight is contributing or generating forward thrust.



Tim.

What you are saying to me, is, i don,t have the right to ask questions or challenge a reply. I accept there a fare more knowledgeable contributors than me on the forum. But i am still part of it and have the right to reply and ask, why or how dose this occur.



I accept wings don,t fall off in normal flight, and this pin is probably for abnormal flight conditions, But if you go back to the beginning of this topic, it indicated to me the in level flight the wing provided some forward force, ie helping the propeller to pull the plane alone.

Maybe it does , as Bob said about the glider, so this bar is in tension all the time if in the glide. 

or may be its in tension only some of the time, 

I don,t know, 



Regard .

Alan

frans(at)privatepilots.nl
Guest

Posted: Mon Jul 01, 2013 7:14 am Post subject: wing lift/drag pins

On 07/01/2013 11:41 AM, Alan Carter wrote:



 	  Quote: 	
		   I don,t know, 


	


Just assume your wings fall off. What is your fuselage going to do? It

will fall straight down after the short moment it looses its forward speed.



Now keep the wings attached. Switch off the engine. Where is the

fuselage going? It moves forward and keeps on moving forward. As the

fuselage has drag, why is it moving forward against the drag? Who is

pulling it?

Is the connecting bar between the two rear sockets under compression or

unter tension?



Frans

Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Mon Jul 01, 2013 9:36 am Post subject: Re: wing lift/drag pins

Hello Frans.

Who is pulling it. Gravity 

It will move is an arc towards the ground.

A wing is similar to a sail on a sailing boat.

You can not sail directly into wind you can get to about 30 degrees of it.

Sorry Frans but at the moment i am still puzzled.

 

At the moment i am thinking this bar has three purposes,

1. to prevent the drag pulling the wing back, which is most of the time.

2. two provide the rigidity to the structure so keeping the front pin locked into its mounting.

3. to stop the wing coming "forwards" in abnormal wing loadings,

Possible very high A/A, near the stall, or gusts, or abnormal flight attitudes.



This puts this bar in compression , tension and neutral loads 



But i am willing to change my mind,as i have used up ask a friend, may be its time to ask the audience,  



Regards .

Alan

rparigoris

Joined: 24 Nov 2009
Posts: 805

Posted: Mon Jul 01, 2013 2:25 pm Post subject: Re: wing lift/drag pins

Hi Group



I have been following this thread with interest. 



I have been picking the brain of an ex Grumman X-29 FSW lead wind tunnel engineer as far as our Europa wings trying to move fore or aft, and all I know at the moment (pun intended) is how much I don't know.



He asked a few pointed questions about the Europa, can you help me out with answering them?:



**** What percent chord is the main spar at?



**** What wing section does the aircraft use?



**** What is the relationship (distance) between the main spar and the aft fitting?



Once I provide him with these details, he will come back with his take on the subject. I will post his answer along with other comments he has made already.



Thx.

Ron Parigoris



BTW Frans, I have always thought of a Gyrocopter as an aeroplane with a big pancake of a wing above you. When you spin up the blades, they don't allow much in the way of airflow through the spinning blades. Think of a big disk you put at a positive angle of attack above you. Kinda neat concept, not very efficient, takes a lot of pushing energy to keep your rotors spinning up to make it act like a solid disc.



Here is an E-Mail I sent:

Hey Guyz

A Europa member was trying to explain to another member why at high angles of attack the wings want to sweep forward.

There are other members that tried to explain in words, one just said well, it's the same reason why a Gyrocopter rotor spins in the direction that it does which with little thought seems to be spinning in the wrong direction.

Attached is a diagram that is a pretty good visualization.

Ron P.



Here's his reply:

No itâ€™s notâ€¦ (a good visualization)



 



You have to apply real numbers to those phoney scalers on that figure.



 



At high AOA the drag is significantly higher than shown, but lift not so much so.  This would pull the L/D resultant much father aft.



 



Those two plots are implying that the L/D of a wing is the same at cruise and at high AOA which we all KNOW is not true! (the reason you never fly a high performance sailplane near Cl Max!)



 



There is one good reason for putting fwd sweep in a wing planform.  It allows less use of washout to keep the tip from stalling.  If the wing is swept TOO far fwd, the twist actually reverses!  The root must be a lower AOA than the tip, sometimes by a lot.



 



The biggest DISADVATAGE to FSW planform wings is structural divergence.  Load the wing up, and without a sufficiently strong wing box structure, the wing tip will twist to a higher AOA producing more twistâ€¦ repeat as necessary until failure (catastrophic I might add!)

Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Mon Jul 01, 2013 2:53 pm Post subject: Re: wing lift/drag pins

Hi Ron.

Glad you are interested.

If you read the topic from the beginning it  imply,s that the sole purpose of this bar was to prevent the wings from being pulled forward all the time during flight.

I,m getting to old for all of this, but as an instructor many years ago i use to draw all the forces on the blackboard,and i never drew a wing vector added to the thrust vector,

So got me thinking why, and i slowly began to come round to thinking there may be some forward component but not occurring in normal flight.

The tie bar came in with the weight increase mod, with the bigger spar pins, the swivelling rear fuselage pin socket and the tie strap on the spar.



Then when we had the in flight break up the tie bar became a mandatory mod for all Europa's with the extra long rear wing pins with big washer and nut inside the wing root.



I think its purpose is as i have stated, and re enforces the whole structure around the wing and mounting points, and i believe this weak spot was part of the break up,

May not have been the initial cause, that may well have been something to do with the Stabalator.



I may be wrong, I have never built an aeroplane, and im just a simple country boy,with a pair of eye,s, but do have the right to post my opinion,



I am polite, never make fun of, or discourage any member from posting, and always willing to listen to another point of view, I am just interested in this particulate topic, and will look forward to your posting, sorry i can,t give you the information you requested,

I just fly the plane.



Regards.

Alan

Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Tue Jul 02, 2013 1:09 am Post subject: Re: wing lift/drag pins

Ron.

Just read your friends replay, 

There was an light certified aeroplane , many years ago,

Not sure who made it, maybe Pipe but i think it was Italian company ?  but it had forward swept wings.

Can, t spell it nether, a  Metersocall

The Europa has a slim straight wing with a little wash out towards the tips. and made of Glass fibre over foam formers, thats a close as i can get it.



Alan

Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Tue Jul 02, 2013 2:35 pm Post subject: Re: wing lift/drag pins

Hello All.

What are the rear tie bar and pins used for.

So for all with an open opinion on this topic , this is what Europa Aircraft Company say about the Tie Bar.

Which gives the full picture, and states Drag and Forward movement.

A requirement to stop the wings fold back, and Forward to stop the wing pulling forward at high angles of attack, and there's no way this forward force would rip the rear mounting out from the fuselage, that occurred after something failed to cause the aircraft to break up.



Quote. Europa 

Tie-bar

As the trailing edge lift pin also acts to contain drag loads and the forward component of lift which is produced at high angles of attack, a tie-bar will be fitted across the fuselage to react these loads. A general arrangement of the tie-bar assembly and associated parts is shown in figure 8.

Fig 8.



Alan



Also acts,? what else does it do ?. Don't answer that please.

Paul M 383

Joined: 19 Mar 2012
Posts: 102
Location: United Kingdom

Posted: Wed Jul 03, 2013 3:20 am Post subject: Re: wing lift/drag pins

>Also acts,? what else does it do ?



It transfers lift to the fuselage and locates the trailing edge of the wing at the appropriate angle of incidence (as does the leading edge wing pin).



Builders' Manual Ch 26, P 26-1: "There are two pins in each wing to transfer lift to the fuselage; one at the leading edge and one, which doubles to take drag loads, is at the trailing edge."



Ch 27, P 27-1: "The wing lift pins locate into sockets, which are to be attached to the fuselage sides, and these hold the wing at the determined angle."



>Don't answer that please.



Oops sorry, too late!



Paul M

G-PLPM

XS Mono 912S

budyerly(at)msn.com
Guest

Posted: Thu Jul 04, 2013 11:19 am Post subject: wing lift/drag pins

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

 Your analysis of the bar and reason for the aft socket pin is good  enough to build the plane or maintain it.

 Understanding the lift affects is really a vector analysis exercise.

  

 I studied a T-28 wing failure accident and we were lucky enough to have a  video of the failure.  The wing failed at a speed of 270 KIAS and the video  clearly showed that when the badly corroded spar and skin failed (main wing spar  is at about the 1/4 chord) the wing went full up as if it were folded and hit  the pilot on the head killing him instantly not aft at all.  In another  accident at an airshow the main spar failed first and began to flutter, the  pilot unloaded and the main spar failed first, and the wing trailed aft because  the wing twisted up and aft spar and upper skin hung on longer.  Tragic  accidents but changes were made and T-28s still fly on well, when properly  maintained.

  

 When building model airplanes as a kid and just experimenting with  tailless designs, using a Clark Y airfoil, it flipped nose up badly even when  the CG was on the CL due to the wing pitching moment.  The same test with a  symetrical airfoil was a piece of cake.  The symetrical airfoil has no  pitching moment until the flaperon was deflected then whamo.

  

 The wing lift vector is not perpendicular to the chord or angle of attack  but is drawn as such in many training documents.  In the US Air Force I was  drafted to rewrite the aero portion of our pilot texts and teach it for a  year.  I had to teach the test questions because most pilots (the generals  included) are not aerodynamicists  they know that the houses  get  bigger when pushing forward and smaller when pulling back unless  you pull too much back stick.  Things like if the engine quits, bail out,  and you can never have too much fuel (unless you are on fire) works in some  cases, but not for us lowly piston engine guys who do not have fuel dumps and  ejection seats.

  

 Our little bird will pull forward on the aft support at modest and high  angles of attack and when unloaded to 1 G or less will go to neutral and then to  compression.

  

 Get it flying and enjoy the plane.

  

 Regards,

 Bud

  

  

  

  

  

  

 [quote]   ---

Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Thu Jul 04, 2013 1:14 pm Post subject: Re: wing lift/drag pins

Hi Bud.

Good to hear from you, It was for me, a very interesting topic as when i look at the wing attachments they look pretty flimsy,

Initially it was said that the load on the pins are always pulling forward,then forward got muddled with forward as if flight forward,which i could not understand,as i have seen many model aircraft wings break off in flight and they just folded straight up, then the overall purpose and workings of this bar and pins slowly fell into place,now i have a much better understanding of it.

I have done some work on the plane, now have independent starter and mag switches, new mounting for ipad, and my torque tube has clamps on s, so no free play,but have just fitted a new mag ht coil at Â£288,made in chine for Â£2.50. 

Flying tomorrow to the Isle Of Wight, weather permitting.

All the best.

Alan

Alan Carter

Joined: 02 Jul 2012
Posts: 378
Location: Kent, England.

Posted: Thu Jul 04, 2013 2:10 pm Post subject: Re: wing lift/drag pins

Hi Bud again,

Its been 14 years since I was flying, and the old memory is not as good.

All I can remember is bendy wings, and use to have a weight and balance sheet and it had this Zero Fuel Weight , think it was about 122000 lbs,

I have this C of G calculator and when I do a weight and balance with the Europa figures I get an Out of Zero Fuel Wight some times, can,t see how this applies  to a Europa, no wing tanks, 

Am I missing something, 

Regards.

Alan

budyerly(at)msn.com
Guest

Posted: Thu Jul 04, 2013 5:57 pm Post subject: wing lift/drag pins

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

 Hope the flight goes well.  Sounds like you have prepared  properly.

 As for CG, I am afraid that since this is such a simple airplane, I pull  out the paper form in my checklist and do a quick calc by hand if I am out of  one of my standard load calculations.  I had a CG calculator on my computer  and it worked flawlessly, but found it took longer to start it up, input the  garbage, and check the result than it took to do it by hand.   Especially with my standardized computations sheets.

  

 I purchased expensive scales for my shop wt and balance work and  calibrated them of course.  Once I do the wt and balance, and compute the  ranges, I must admit I have become somewhat cavalier in my wt and balance  checks.  Yes, I am acquiring bad habits.

  

 The reason is, or should I say excuse:

 When we finish a plane here we do a number of calculations.  Initial  test flight; then max pilot and pax wt with zero fuel and baggage for max  forward CG; then max aft which is usually a 120 pound pilot, max fuel and  max baggage; typical pilot and copilot with full fuel and 2.5 gallon landing and  a couple of flight bags for local flying; cross country pilot and passenger,  full takeoff and landing fuel, full baggage or what the CG or GW will  allow.  Then I print them up on a sheet for inclusion in the  handbook.  Should the owner exceed any of these set CG comps (like taking  off well over max design gross takeoff weight), I go fly with them and do stalls  noting the increases and difference in break, slow flight,  maneuvering and approaches and landings with them until they are  comfortable, understand the load limit restrictions (as they are well into the  safety factors the G limits are changed).  I especially do this if the  empty plane is really heavy.  Many times I add stall strips to give  better buffet warning prior to the stall.

  

 I have found that I prefer the CG of a fully serviced with oil and coolant  airplane empty CG to be 60 inches.  That way a 180 pound pilot, full or  half fuel load for the test flight and only a flight bag allows me to easily  control the plane even if the trim should fail or run away.   On cross  country cruising, this allows full fuel for takeoff, full luggage at 80 pounds  and another 180 pound pilot without worry.

  

 Regards,

 Bud

 [quote]   ---

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