Which aircraft had laminar flow wings?

[spicmart]

An interesting article HoHun shared at Flugzeugforum:

Laminar- vs. Turbulent-Flow Airfoils - KITPLANES

Airfoils break down into two general classes based on the behavior of the boundary layer.

www.kitplanes.com

He names the disadvantages of a laminar airfoil at turbulent flow:
- More drag than a conventional profile better suited for the same purpose.
- less maximum lift than a conventional profile

Disadvantages of laminar airfoils at even largely non-turbulent airflow_
- tendentially less maximum lift than conventional airfoils

 

[tomo pauk]

He names the disadvantages of a laminar airfoil at turbulent flow:
- More drag than a conventional profile better suited for the same purpose.

NAA, NACA and even Germans back in ww2 disagree, if the purpose is to go fast.

- less maximum lift than a conventional profile

Horses for courses.
A ww2 transport aircraft will do just fine with the ancient Clark Y profile, something required to do 400-450-500 mph will need any drag reduction it can have, the wing profile chosen being high on the priority list.

 

[pbehn]

An interesting article HoHun shared at Flugzeugforum:

Laminar- vs. Turbulent-Flow Airfoils - KITPLANES

Airfoils break down into two general classes based on the behavior of the boundary layer.

www.kitplanes.com

He names the disadvantages of a laminar airfoil at turbulent flow:
- More drag than a conventional profile better suited for the same purpose.
- less maximum lift than a conventional profile

Disadvantages of laminar airfoils at even largely non-turbulent airflow_
- tendentially less maximum lift than conventional airfoils

The P-51 (Mustang Mk I) had lift to spare for level flight . NAA proposed to the RAF reducing the wing span to make it faster, a genuine 400 MPH. Happily for its future the RAF declined because it would affect climb and take off.

 

[spicmart]

It has been mentioned that wooden surfaces are smoother than metal ones. So wooden high performance planes like the Mosquito, Hornet and some Russian fighters might have a drag advantage regarding laminar flow. Taking construction under account their weight penalty would be less compared to metal airframes of the same designs as one has to make the wing more rigid in order to get the as good a non-turbulent flow as possible.

I mean with that that if you built a Hornet in metal configuration it would be, say, about 15 % less heavy than the actual one. But as it has a laminar flow airfoil this metal version must have heavier built wings due to tighter tolerances required than if this were not the case. Then it would be only, say, 10 % lighter.
Is this assumption okay?

 

[Simon Thomas]

Tighter tolerances does not necessarily mean a heavier wing.

North American did an excellent job of fit and finish on the P-51. If Brewster had a contract to build P-51's, you can bet they would have significantly higher drag for around the same weight.

 

[FLYBOYJ]

Tighter tolerances does not necessarily mean a heavier wing.

North American did an excellent job of fit and finish on the P-51. If Brewster had a contract to build P-51's, you can bet they would have significantly higher drag for around the same weight.

The "Fit and Finish" requirement would have been the same across the board and IF a subcontractor (like Brewster) "would have" built P-51s under license, they "would have" had to comply with the same requirements put out by NAA or they would not have been accepted by the AAF, let alone their own internal inspectors!

Aircraft are mainly built in assembly jigs, unless you have poor structural assemblers, namely riveters, you're looking at a "cookie cutter" process. You get what the assembly jig gives you.

 

[Simon Thomas]

Brewster would have been given the required specs for building the Corsair, however they were so badly built that none of them saw front line service.

 

[FLYBOYJ]

Brewster would have been given the required specs for building the Corsair, however they were so badly built that none of them saw front line service.

That's right, because the company was a train wreck and the government actually took over the place! All segments of manufacturing discipline fell apart.

 

[spicmart]

Tighter tolerances does not necessarily mean a heavier wing.

North American did an excellent job of fit and finish on the P-51. If Brewster had a contract to build P-51's, you can bet they would have significantly higher drag for around the same weight.Ich

The author of above article about laminar vs turbulent airflow article is knowledgeable in the industrie. I guess he knows about tolerances and weight...

 

[Simon Thomas]

I heard him talk at Oshkosh a few years back. He knows his stuff, except when he fell for the Stirling wingspan hangar limitation myth.
Stressed skin wings on combat aeroplanes would rarely need additional thickness to maintain the shape tolerance.
Barnaby's article was aimed at homebuilts, which usually are not stressed metal skin.