Gallery of Fluid Mechanics

Condensation on a B2 bomber, photographed by Bobbi Garcia
The above image was taken by Bobbi Garcia at Rohmann Services. The image is an official Air Force photo and therefore is in the public domain. Click on the image to see a larger ( 54 Kb ) version. Jeff Wilkinson has also made a couple of high resolution versions available here.

The photo at the right shows some great condensation on a B2 Stealth Bomber. The photo was taken by Bobbi Garcia in an F-16 chase plane.

The physical cause of the cloud is not immediately obvious. The image doesn't have the classic cone-shaped appearance of a Prandtl-Glauert cloud, although a similar pattern can be seen here. According to Bobbi Garcia (private correspondence and comments on Jeff Wilkinson's Sound Barrier page), the condensation would appear now and then while in level flight. Furthermore, I couldn't see any evidence of condensation due to delta wing vortices similar to those seen on the Concorde. Although the B2 is clearly in a banking maneuver here, the general consensus is that the above pattern is not connected with high lift maneuvers. I think that a reasonable guess is that the clouds are due in part to lift enhanced by the Prandtl-Glauert singularity. The speed of the B2 is likely to correspond to a Mach number of 0.6 so that the enhancement is likely to be weak. The latter point may be the reason the shape of the cloud is non-classical.

A strange feature of the cloud is that it seems to extend beyond the wing surfaces. This is particularly evident in the full-size version and a second image which appears on the Edwards Air Force Base description of the photo.

You will also notice a dark band in the cloud behind the flying wing. This band might be due to the unusual engine exhaust or an optical effect.

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