Film of Shockwave forming on wing of XP-51

[John]

There is reference to a motion picture film done by NACA on the formation of shock waves over the wing of the P-51. I had read about this many years ago but had not seen it until now!

See it here: http://www.youtube.com/watch?v=mU6i0Ix5QvI

Thank you to the person who posted it.

The drag rise between .7 and .8 Mach resulting from the compression shock over the wing is quite significant. Looks like the more inboard portion of the wing where the section thickness is greater gets the earlier shock waves. One realizes how true Eric A. was about the "too much acceleration at the wing root" being the cause of much drag on the Mustang at high speed. The shock probably begins more at the thick portion of the wing just where the P-51's famous kink ends. The kink on the P-51D may actually help a small amount nearer the root since it is extended further forward.

How much faster can our racing Mustangs go until this drag rise takes over?

[laminar]

Re: Film of Shockwave forming on wing of XP-51

very cool

Elliot

[AirDOGGe]

Re: Film of Shockwave forming on wing of XP-51

That's one of my favorite Youtube channels.

The "person" who posted the video is the NASA Cultural Resources division. They have over 500 videos of the type available for viewing there. Fascinating stuff.

Here's a link to the main page:

LINK: http://www.youtube.com/user/NasaCRgis

[BillRo]

Re: Film of Shockwave forming on wing of XP-51

Interesting Find. You can see the effect of the shock wave in the condensation and the activity of the tufts. If you go faster you can actually see the shock wave itself. As a young engineer in training at De Havilland I worked in Flight Test for a while and flew in a Trident piloted by John Cunningham no less, doing emergency descent tests (how long does it take to get down to 10K ft after loss of pressurization) with aft CG. He took it to M=0.945 and walking around the cabin and looking out of the windows, you could clearly see the shock waves on the thickest part of the wing standing up about 18" high.

At Reno's 5,000' on a standard day M=1.0 is 748 m/h so a 500 m/h Mustang is at about M=0.67, not quite at the drag rise. If it got to 550 it would be a factor. Probably of more Mach interest is propellor tip speed and Formula Ones run into that. We have a table in our Design Guide that I made, which relates engine RPM, Temperature (Mach Number is tempeature dependent) and Prop diameter at a given forward speed. You could look at this if IF1 had not (temporally we hope) lost their website.

BillRo

[John]

Re: Film of Shockwave forming on wing of XP-51

Thanks all,

and for the NASA link!

... also to BillRo for the estimated calculation on the speed the drag rise for the P-51 should occur(excluding pulling G's I would assume?)

Prop on Mustang at 1200 to 1400rpm?? The tips must be already at Mach!?

Pretty fast for a commercial liner there M=0.945 -sounds scarry.

John