Posted on 03/07/2019 8:42:38 AM PST by DUMBGRUNT
The images feature two T-38s from the US Air Force, flying at supersonic speeds less than nine metres (30 feet) apart, with a stream of shockwaves emanating from either side. There is also an image of one, single T-38 flying on what is described as a "knife's edge"...
"We never dreamt that it would be this clear, this beautiful," says JT Heineck, a physical scientist at NASA's Ames Research Center.
(Excerpt) Read more at sciencealert.com ...
Too cool.
Too cool is right. It is hard to believe they’re not computer generated graphics.
Hmmm, that’s pretty amazing, how perpendicular the shock waves emanate from the front of the aircraft. I wonder at what speed they propagate, the speed of sound? Looks like it would have to be much faster due to the slight angle of the bow wave.
Great screen backgrounds. I have hundreds that just cycle through.
Interesting how they interfere with each other.
They aren’t perpendicular, each line is going out in 360 degrees, you only see a cross section here.
Cool picture, though!
https://www.thenakedscientists.com/articles/questions/what-produces-lift-during-knife-edge-pass
from link:
When an airplane does a knife-edge pass (wings vertical), where is the vertical component of lift coming from to keep it in the air?
Thanks!
Cameron
Answer
Dave - So, the plane is basically flying on its side. The wings can’t be doing anything because they’re vertical. So, the lift must be coming from somewhere else. When you watch them doing it, they’re actually quite a big angle. So, they’re not flying horizontally. They’re sort of flying at 20 or 30 degrees to the vertical. And so, you’ll be getting some lift from the side of the body of the plane, from the side of the fuselage. Some from the tail plane itself will be giving you some lift and mostly, the kind of planes which do this have got very, very large propellers which can throw an awful lot of air backwards. So, because the plane is pointing upwards, that air is being thrown downwards, and so you get an equal opposite reaction and the plane gets pushed upwards.
Beautiful...
It looks like the trailing aircraft is maintaining speed with a lot less power.
A “knife-edge” shot of a single T-38 in supersonic flight.
Image: NASA
https://i.kinja-img.com/gawker-media/image/upload/tjumihlodgtgxu1xedau.jpg
BOSCO Chief Engineer Brian Strovers and research engineer Paul Dees calibrate one of three cameras positioned to be able to capture images of supersonic research aircraft. Using a special hydrogen alpha filter, and positioning the cameras to use the sun as a background, NASA researchers are able to observe shockwaves coming off aircraft as they fly faster than the speed of sound, or supersonic. This required pilots to fly through a designated position that was approximately 100 feet in diameter, while flying at supersonic speeds.
Spiff-tastic!
I’m partial to the F16, myself, but I have to say that the F5/T38 is a good looking little airplane.
Thanks!
The shock waves build up as the vehicle approaches speed of sound, (Mach 1) then compress closer together at the speed of sound. Once Mach 1 is exceeded the shock waves start angling rearward. The faster the speed, the sharper the shock wave.
Here's one of my favorite pics of Thrust SSC breaking the sound barrier. The lighter portion aft of the shock wave is the dust it's kicking up as the car passes over the ground.
Again in your diagram, "The faster the speed, the sharper the shock wave." - agree.
But in the image posted by the OP, the waves are at least 80 degrees perpendicular to the aircraft! So what's up with the NASA image of two aircraft flying faster than the speed of sound?
The images feature two T-38s from the US Air Force, flying at supersonic speeds less than nine metres (30 feet) apart, with a stream of shockwaves emanating from either side.
I would like to see a zoomed out version of the NASA image. Perhaps then one could better see the curvature of the wave front.
Even so, there is "sumpin" odd about the speed at which the wave must propagate (i.e., faster than the speed of sound) to have such a perpendicular departure from something that is itself traveling at sonic velocities.
NASA Captured Two Jets' Supersonic Shockwaves Merging By Applying New Tech To An Old Idea
NASA's new very high-speed camera paired with the 'Schlieren' photography concept will help in the development of practical supersonic air travel.
By Joseph Trevithick March 6, 2019
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.
