Are NACA airfoils used in modern aircraft design?

Question

I know that NACA is famous for its ducts:

^{Gratuitous Ferrari F-40 from Wikipedia. Mmmm... pretty...}

It is also well known for its airfoils, and many planes in the early years of aviation used NACA designed airfoils for their wings (for example the Piper Cherokee referenced here).

^{Piper PA-28 also courtesy of Wikipedia}

Do current aircraft manufacturers still use stock NACA airfoil designs, start with a NACA standard design then modify it to meet needs, or are the airfoils completely bespoke?

I'm asking about the major airliner manufacturers like Boeing & Airbus, regional jet builders like Embraer, as well as private/GA companies like Cessna, Gulfstream, and, of course Piper. Information on the (few, dozens, hundreds?) of other aircraft manufacturers (and kit designers) that don't pop to the top of my head is also welcome and appreciated.

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Thinking about this further, I realize it could quickly devolve into a very broad this aircraft uses a NACA standard wing, that one doesn't list. That's not really my intent. A simple yes, this aircraft/wing from 5-10 years ago uses a NACA standard would answer the question completely, as would a the last one I'm aware of is from 35+ years ago.

Also, the use of "modern" is rather vague as the Boeing 757 certainly feels "modern" (having been launched in 1982) but has been out of production since 2004, while the 747 started production in 1969 and is still being built. If someone wants to jump in to help define "modern", I'd take no offense.

Answer 1

Just three data points: The tail surfaces of the Pilatus PC-12 still use the venerable NACA 0012, even though a better alternative (from the Wortmann FX 71 L series) was proposed. It did not help that the Wortmann airfoil is used on many small airplanes, has more lift and less drag and an abundance of data exists on it: The (mainly British) engineers at Pilatus were too conservative to use anything newer than an airfoil from the 1920s.

Pilatus PC-12 (picture source).

The wing of the Dornier Seastar, designed by a group of old Dornier engineers in the early 1980s, used the same airfoils as the venerable Do-17 of the 1930s, namely the NACA 23012. Later flight tests showed the need to add a leading edge droop on the outer wing, a modification that cost several knots in top speed and would have been entirely avoidable with better airfoils and/or the use of washout.

Dornier Seastar. Picture by Rschider (own work).

The excellent Polish aerobatic glider Swift S-1 uses indeed a NACA 6-digit airfoil, the $64_1412$. As Jerzy Makula explained to me, it gives excellent snap roll and spin control, and when flying the prototype, I could control the exit direction from a spin within ±15° with very little practice. Jerzy simply took what had worked before.

Swift S-1. Picture by TSRL (own work).

Generally, small companies or experimental airplane builders still rely sometimes on the NACA series, but in general better alternatives exist. Big companies use custom-made airfoils, helped by computer codes which model not only the two-dimensional flow around the isolated airfoil, but can optimize the specific wing section by including the influence of engine nacelles, pylons and the fuselage. Well-designed wing roots do not use one single airfoil, but a three-dimensional shape which minimizes interference drag.

This is true even for glider companies. While Wolf Lemke used his own creations for the early LS series of gliders on the basis of their good looks (and with good success), todays gliders are designed in the computer, helped by university departments which relish the chance to let students work on real-world designs.

Answer 2

NACA airfoils are used still used in aircraft, though most of the airfoils used are modified in some way.

For example, the Cessa uses either pure or modified NACA airfoils in most of its Cessna Citation jets, though newer models tend to use Cessna's own airfoils.

For example, the Citation V uses modified NACA 23014 airfoil at the root and modified NACA 23012 at the tip.

^{"Cessna uc-35a citation 560 ultra v arp" by Adrian Pingstone - Own work. Licensed under Public Domain via Commons.}

The recent ones, like the 750 Citation X uses Cessna's own Cessna 7500 airfoil.

Boeing, on the other hand has been mostly using its own airfoil designs from day one, though it has 'borrowed' ideas from NACA series (like supercritical design)

On the military side, the F22 Raptor uses a modified NACA 6 series airfoil. According to Public Domain Aeronautical Software

F-22 uses a uncambered 64A section with 5.92 percent thickness at the root and 4.29 percent thickness at the tip

For a detailed list please see The Incomplete Guide to Airfoil Usage.

Answer 3

The Cessna 172R uses a modified NACA 2412 airfoil and has been in production since 1956 to the present. This also substantiates the excellent points raised by aeroalias (https://en.wikipedia.org/wiki/Cessna_172).

This airfoil guide also specifies the airfoils used for wing root and wing tip for a large range of aircraft and helicopters (http://m-selig.ae.illinois.edu/ads/aircraft.html).

From this airfoil guide, you can also check out any "modern" aircraft you are interested in and determine if the NACA airfoils or any other type of airfoils are used.

P.S. I just saw that aeroalias also referenced the airfoil guide. Do check it out, it's a fantastic resource.

Answer 4

There is theory, and then there is real life. The advantages (for general aviation) of modern airfoils fall mostly in the former category. This paper on airfoil selection explains this much better than I ever could. My designs (full disclosure: these exist only on paper up to now) tend to get a "catalogue" airfoil, because the properties and behaviour can be predicted beforehand.

I would hate to design an aircraft, then put in 4-5 years of work building the thing and finally end up with an unmanageable beast because I changed one parameter of a bespoke airfoil in the wrong direction. To prevent that from happening I can live with almost any (reasonable) reduction of theoretical efficiency.