I'd be extremely surprised if that design actually broke mach. Tube fins are extremely high drag compared to standard fins.
Yeah, that's an interesting choice...
I read an interesting webpage about a year ago about jet intake designs on supersonic aircraft and the different effects of Mach shockwaves and air intake efficiency. It was a very interesting read because it detailed not only the problems and effects at different flight speeds, but sizing and many of the solutions used, and why they work the way they do.
For instance, the optimum size/shape of the intake changes markedly depending on the flight speed and air density, as it relates to the "local speed of sound" (which varies with air density) and shock wave effects. An intake that is optimal at takeoff is FAR too large at altitude and speed, and therefore extremely draggy. Intakes that are optimally sized for altitude and speed are too small at takeoff, which can result in the compressor blades "stalling" out for lack of air. Also, the supersonic airstream has to slow to subsonic speeds to flow properly through the engine. That is why there are a myriad of intake designs, from the old F-4 Phantom intakes that used a "vane" in front of the intake that moved to divert some of the air going into the intake and manipulate the shock wave coming off it so the shock wave stayed out of the intake itself. The Russian MIGS used a 'half cone' that could slide back into the intake or out further in front of it, reducing the intake size for supersonic flight. The Harrier (among others) use small spring-loaded air doors that open up to admit more air at low speeds, and snap shut at high speeds to reduce the effective intake size. Of course the F-15 and F-14 had those drooping moveable intake 'wedges' that extended up to the front of the wing.
Now how does this apply to the subject of tube fins?? Simply put, the tube fin 'intake' would create a conical shock wave inside each tube fin, which would compress the air as it passed through the shockwave, and when supersonic air goes through a shockwave, it loses energy (to maintain the shockwave) and goes subsonic... so essentially the tubefins would be acting as huge aerodynamic brakes...
Interesting stuff... OL JR
