Settle a bet: Mach speeds

(OXMORON1) wrote:
Walt wrote:

BTW, on the deck 760 mph is close to .1M (STP), so when
your car is showing 76 mph, you're buzzing along at about .1M. (For
interstate travel, 75 mph is 12.5 miles in 10 minutes . . . we just
completed about 6000 miles of driving where I used this sort of mental
T=D/R to predict ETAs thus boggling my better half. Same sort of calcs
can be used ina light plane such as C152 . . . 6gph = 1 gal in 10 min,
90KTS = 1.5 nm/min; 120(tailwind)=2 nm/min. As above, use the
calculator if things look tight. (If they do you've screwed up.)

Glad I am not the only one running continuous ETAS while cruising down the
Interstate :-) Drift gets to be a bitch though!
Habit! Ingrained by instructors who are really old farts now!

Speaking of winds and such, as an "old fart" flight instructor myself
(it's all downhill after 40, right?) here is a little homemade
question that I find many aviators both military and civil routinely
get wrong:

If you takeoff from airport "A" and fly 200 miles into a 20 mph
headwind to airport "B" at 100 mph (TAS) and then turn around and
fly back to airport "B" now with a 20 mph tailwind at the same TAS
will you complete the roundtrip flight in the same time as if you had
made the flight in no-wind conditions?

Yea or nay?

(Correct answer gets a cigar and large bucket of his favorite
drink....)