What is the function of leading edge strip?

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Twodeaddogs

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Look at the wing from in front. It is the entire leading edge of the wing, usually made from one piece or several smaller pieces of aluminium or plywood, to provide the aerodynamic shape of the front of the wing. The use of the word "strip" is completely wrong.
 

WBNH

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In the image provided, I would have expected that to be be more accurately labeled a Leading Edge Wrap.

Leading edge strips do exist, though not pictured in your image. Sometimes called a stall strip like on a Cirrus (inboard), or a leading edge cuff on Searey (outboard) for example.
 

BoKu

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https://i.stack.imgur.com/mciE7.jpg .....Hi,I understand the fuctions of every part of a fabric wing but not its leading edge strip,so what is its function?...
It helps enforce the wing contour at the leading edge where the curvature is tight. Otherwise the fabric tends to sag down between the ribs. And when that happens, it doesn't have the intended cross-section.

...can I remove the leading edge strip without hurting the wing performance?
No, you can't. And, why would you want to? It's only a few dollars worth of material adding almost no weight.
 

Aerowerx

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Isn't the leading edge (typically, the area in front of the main spar) the most critical part of the airfoil shape?
 

BBerson

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Need something to glue the fabric to on the leading edge. Could be tube (ultralight) or something. Can't be nothing or the nose ribs need to be stronger and closer spaced.
 

wsimpso1

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The first thing to know is that the piece of sheet metal or thin plywood is giving you a leading edge profile that is much more "true" to the intended foil shape than you can get without it. This is important to obtaining both low drag and good stall behaviour. If you were to skip this part, the fabric would pull in giving a shorter and blunter nose section between ribs. The solution would be either a compromise airfoil section at the ribs that would give a more favorable "average" shape or a lot more half ribs forward. WEIGHT IS THE ENEMY. That very light piece of material is way lighter than more half-ribs and gives a better airfoil than without it. so even if this were the only benefit, it would be worth it, but there is more.

The second thing it does is it gives a good place to anchor the covering. Bottom surface glues to the piece above the leading edge and wraps aft. Top surface (may be the same piece of fabric) glues to the bottom fabric below the leading edge and wraps aft. All this bonding needs a good area to bond to in the first place, then needs to be bonded in an overlap too, or the joint will not be durable. Could you use thicker fabric to do this. Maybe, but at a price of much more weight. WEIGHT IS THE ENEMY;

The aero forces (from local air velocity) are highest very near to the leading edge. There is direct positive pressure pushing in at the stagnation point equal to the dynamic pressure of the free stream. Once you get aft a very short distance aft of the stagnation point, local velocity goes very high. For any foil, you can look up v/V curves at Cl of zero and at another Cl, so you can estimate the v/V at any spot and Cl, then local velocities. The forces trying to push or pull the skin fabric (and underlying structures) are highest in the front quarter of the chord.... The leading edge strip provides local reinforcement to hold the airfoil shape.

Last, in many airfoils, the leading edge strip attaches to the forward spar on top, wraps around the front of the foil and attaches to the forward spar on the bottom. This forms a D shaped tube, and is called that the D-tube. The D-tube is several times stiffer and stronger in torsion than just the spar, and in many fabric covered wings is the major torsional stiffness and strength of the wing. Could you just use a beefier spar for this? Yeah, but it would make for a much heavier airplane. WEIGHT IS THE ENEMY...

So, it makes for lower drag and better stall at low weight, anchors the covering nicely at low weight in itself and in the covering, reinforces the palce where aero forces are highest, and in many airplanes provides a light and torsionally stiff/strong structure for the wing.

Pretty cool to do all that stuff at very low weight...

Billski
 
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