Chris Blake
If I were Bill Gates, I\'d pay for one of these up-front. SWEET!!
Arthur Hu
800 mph would be supersonic. .95 mach at altitude is somewhere in the neighborhood of 650 mph, about the same as the B-52 or F-86
Glad it wasn\'t just me thinking ....800mph...subsonic..???..!!! 800mph is Mach 1 at -15000ft - a bit tricky to achieve!! lol! This link shows what it should be:
So that leaves - how fast is this aircraft? If it is 800mph, then it is a really serious piece of kit? But.. ...much more likely, somebody has divided the speed of sound by the 0.925 performance, instead of multiplying it!! So the actual speed is probably just under 700mph, still not too shabby!!
Dan K
The speed of sound is EXTREMELY variable, with temperature, pressure altitude, etc... 800mph is entirely feasable as mach .95
Richard Mathie
the fastest civil aircraft ever was concord or the TU 144, they were both civil aircraft and cruse at about Mach 2 or 1334 mph
650mph is about the avearage speed of sound at ground level.
At 40,000ft the air is thinner and the speed of sound is higher, though I suspect 800mph (ground speed) would only be possible with a strong tail wind, such as the jet stream.
LSS is calculated by temperature not altitude. Altitude is irrelevant as one day at 20,000 feet it can be -25 C (ISA) and with a temperature inversion it could be -10 C

Formula for LSS:

Temperature in C 273 Kelvin (Square root the answer) x 38.94 = LSS in Knots

x 1.15 = LSS in MPH

i.e. at 40000 feet its -56.5

-56.5 273 = 216.5 (Sq root 216.5) = 14.71 x 38.94 = 572 Knots x 658 MPH
Gabriel Jones
Speed of sound gets slower as altitude goes up. It is related to the density of the medium through which it is traveling. speed of sound is = to the sqrt of the C(coefficent of stiffness)/p(density)...
Facebook User
Fosteve is right. .925 Mach is nowhere near 800MPH. At ANY altitude or temperature, but I\'m sure the jet could hit 800 in a dive.... We\'ve all heard of \"vaporware\" software... this is what\'s called a \"Vaporcraft\"
Roger Bamkin
Fast ever it says in the headline .... apart from the Concorde that is. I see its correct in the article so maybe a different author?