Which aircraft had laminar flow wings?

[drgondog]

I take it you meant that the location of the max T/C was at those points. An airfoil with a T/C of 60% would be rather thick.

Correct - I edited it for clarity. The max T/C was 16.5% at Root chord and at location 37.5% of chord.

Edit: Some great information in your post. Do you know the dates of when they started & finished design work on the airfoil?

The Intensive analytical work of the 10 person/fourteen day design work began immediately after the LOI was signed with Sir Henry Self. In parallel airframe design for the wing started with NACA 23016 airfoil 'just in case' the Low Drag wing airfoil was unsuccessful. Very little, if any re-work was required, following successful wind tunnel results at GALCIT - report submitted in July 1940. By the end of July all of Schmued's preliminary designs were in the hands of the Experimental shop. That said, the empennage and most of the fuselage had already been fabricated, awaiting the wing and powerplant designs.

 

[drgondog]

In fact, the term "laminar flow" wing is misleading, as the surface is not smooth enough to prevent turbulent flow. There was a Royal Air Establishment study that used a P-63 with polished filler paint, and that specific airplane attained laminar flow on the wing up to 60% of the chord behind the leading edge; however, the measured waviness of the surface was found to be less than 0.005 inches, unattainable in the field.

During the full scale wind tunnel tests at NACA Langley, the P-63 in full sealed condition had a CDo of .0171 compared to P-51B value of .0173 (strictly due to the P-63 wing when compared to P-39) but when both restored to 'as delivered' condition the P-63 had a CDo of .0221 vs .0201 for the P-51B. The test velocity conditions were at 100mph, or RN of approximately 1.84x10^6. Th production methods and surface preparation were superior with respect to 'standard' aircraft delivered.

 

[Conslaw]

Despite the P-63 having a much cleaner wing, in the 1946 Cleveland Air Races, Tex Johnson won the piston-powered division in a heavily-modified P-39Q. (Tony LaVier was 2nd in a P-38, by the way.) The other planes were an FG1D, and several P-51s and P-63s. An article on the race can be found here.

 

[Zipper730]

Was the P-53 or P-60 designed to use laminar-flow wings?

 

[wuzak]

Was the P-53 or P-60 designed to use laminar-flow wings?

Yes.

 

[Zipper730]

Yes.

Oh that's pretty cool. I didn't know that. That said, I doubt they were anywhere near as good as the P-51 Mustang.

The detail-design on that was (despite being completely straight) fabulous!

 

[gumbyk]

Spontaneously I would say the Yakovlev's wings are less draggy than those of Me 109 and Fw 190....

Well, they're smaller than the FW-190 and the 109.
The yak has a fairly clean wing, but its not a laminar flow (supercritical) airfoil.

 

[thunderbird]

As several people have mentioned, no production aircraft achieved laminar flow for any significant benefit. The P-51 achieved a low parasite drag number, by paying close attention to manufacturing processes, primarily bumps, better skin joints to reduce gaps and forward facing steps, and better detail design to eliminate unnecessary roughness and protruberances.

 

[Zipper730]

As several people have mentioned, no production aircraft achieved laminar flow for any significant benefit. The P-51 achieved a low parasite drag number, by paying close attention to manufacturing processes, primarily bumps, better skin joints to reduce gaps and forward facing steps, and better detail design to eliminate unnecessary roughness and protruberances.

That said, I doubt the P-60 measured up

 

[tomo pauk]

As several people have mentioned, no production aircraft achieved laminar flow for any significant benefit. The P-51 achieved a low parasite drag number, by paying close attention to manufacturing processes, primarily bumps, better skin joints to reduce gaps and forward facing steps, and better detail design to eliminate unnecessary roughness and protruberances.

As measured by Germans, wing section of P-51 was much less draggy than of either Bf 109 or Fw 190. Add the excellent raditor set-up for a tiny cooling drag and there is a big advantage for the P-51.

 

[spicmart]

tomo pauk
Hello.
You once wrote that the airfoil of the Me 109 / Ki-61 had been obsolete and quite draggy. Could you tell where you have read that?

 

[drgondog]

tomo pauk
Hello.
You once wrote that the airfoil of the Me 109 / Ki-61 had been obsolete and quite draggy. Could you tell where you have read that?

Dr Hoerner devotes an entire chapter analyzing the Bf 109. Chapter 14 "Fluid Dynamic Drag" - see pg 14-9 for tables of comparisons between Bf 109 and P-51 in which both CDt and CDw are ~ 2x over the Mustang..

Notably the 109 wing had smaller Thickness Ratio (14.2% Max T/C at root, 11.3% at tip vs P-51 w/16 % Max T/C Root and 12% for Mustang tip). All factors equal, it should have had less profile drag than the Mustang based on 'thinner wing' in velocity range below significant compressibility. RAF and LW concluded the same thing and were mystefied regarding the extreme lower drag values of the P-51.

We know that several factors were involved to reduce Total Drag of P-51 vs other period fighters. Such As - The fuselage design of employing 2nd order conics, imbedding rdiator/oil cooler into lower fuselage with intake aft of the wing lifting line, optimizing 'scoop/gutter' to peel BL effect at intake entry, 'interior plenum design forward of radiator/intercooler to improve the more gradual reduction of flow to the radiators which achieved lesser boundary layer separation and more equal pressure distribution on front face, the variable exit door controlled by coolant temps achieving a degree of Meredith 'effect' to reduce cooling drag.

Last but most definitely not least was the superior low drag/high speed airfoil and outstanding surface quality management of the wing.

Back to the 109.

Perusing through the 109 analysis I did not find a correlative CDparasite vs RN for the wing only, but did find CDwing was 37.5% of total CD of the entire airplane,

He states that for total wing CD for the 109 - incl. profile and friction and surface imperfections - equaled 37.5 % of the total CD.

The Total CD includes the wing CD, the iterference drag, the CD for fuselage, empennage, cockpit, radiator (incl pressure drag), carb intake plus the induced drag.

 

[tomo pauk]

tomo pauk
Hello.
You once wrote that the airfoil of the Me 109 / Ki-61 had been obsolete and quite draggy. Could you tell where you have read that?

Germans tested the airfoils from Bf 109, Fw 190, P-51 (and a few more), and found that wings' profile drag coefficients were 0.0101, 0.0089 and 0.0072, respectively. That is despite the wing of the Bf 109 being with the lowest t-t-c ratio.
(reference pg. 338 from book 'Vee's for victory')
Ki-61 is worse off, since it had the same profile as the Bf 109, but of greater t-t-c - 16%, ie. same as P-51. Wing area on the Ki-61 was also greater, making the wing-related drag greater still.

 

[drgondog]

Germans tested the airfoils from Bf 109, Fw 190, P-51 (and a few more), and found that wings' profile drag coefficients were 0.0101, 0.0089 and 0.0072, respectively. That is despite the wing of the Bf 109 being with the lowest t-t-c ratio.
(reference pg. 338 from book 'Vee's for victory')
Ki-61 is worse off, since it had the same profile as the Bf 109, but of greater t-t-c - 16%, ie. same as P-51. Wing area on the Ki-61 was also greater, making the wing-related drag greater still.

Hi Tomo - check the source for 0.0089 value for P-51 wing profile drag.

The NACA Langley full scale tests on P-51B-1 43-12095 at RN=6.19x 10^6 was 0.0070. At RN=1.84x10^6 for 1/4 scale wind tunnel model it was 0.00760.

 

[tomo pauk]

Hi Tomo - check the source for 0.0089 value for P-51 wing profile drag.

Germans tested the airfoils from Bf 109, Fw 190, P-51 (and a few more), and found that wings' profile drag coefficients were 0.0101, 0.0089 and 0.0072, respectively.

 

[spicmart]

Germans tested the airfoils from Bf 109, Fw 190, P-51 (and a few more), and found that wings' profile drag coefficients were 0.0101, 0.0089 and 0.0072, respectively. That is despite the wing of the Bf 109 being with the lowest t-t-c ratio.
(reference pg. 338 from book 'Vee's for victory')
Ki-61 is worse off, since it had the same profile as the Bf 109, but of greater t-t-c - 16%, ie. same as P-51. Wing area on the Ki-61 was also greater, making the wing-related drag greater still.

Thanks. but what does t-t-c ratio mean?

Naive assessment: it does not depend on the bluntness of the leading edge. The 190's was more blunt than the 109's.

 

[tomo pauk]

Thanks. but what does t-t-c ratio mean?

Thickness-to-chord ratio, usually expressed in percents.

Naive assessment: it does not depend on the bluntness of the leading edge. The 190's was more blunt than the 109's

Bluntness is above my pay grade.

 

[drgondog]

Be nice ifmy brain worked every day instead of even numbered days

 

[tomo pauk]

Be nice ifmy brain worked every day instead of even numbered days

A lot of us would've kill, in order to have that kind of brain...

 

[drgondog]

A lot of us would've kill, in order to have that kind of brain...

Not the one on 'odd' days.. 'That one' lands you in hospice.