Settle a bet: Mach speeds

On Wed, 19 May 2004 09:42:21 -0700, "Darrell" wrote:

I think that value should be 100 ft/sec.

Good thing I haven't been to any cocktail parties since the post.

all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
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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!

Rick Clark
MFE

(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....)

Mike Marron wrote:

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....)


Oops!

The above question should read, "...turn around and fly back to
airport "A" now with a 20 mph tailwind at the same TAS."

In other words, 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 "A" 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?

"Peter Stickney" wrote in message
...
In article M7Mqc.31369$Md.30236@lakeread05,
"Darrell" writes:
I think that value should be 100 ft/sec. Mach one is about 600 Knots =
1
NM/Min. One NM = 6,000'. Divide 6,000 by 60 (seconds in a minute) and
you
get 100, not 1,000.


Darryl, It's a good thing they had somebody behind you with the map

600 Kts is 10 Nautical Miles/minute, not 1.

BTW, you'd probably know this: Is theere any truth to the story that
a B-58 got itself into some manner of perdicament up over Alaska, near
one of the airbases. (For the same of Argument, I'll say Eielson, but
I don't know) The Pilot was busy trying to keep teh airplane flying,
and things were kinda touchy. While things were gyrating, the Nav
tried calling the Pilot & DSO, and for some reason (Either they were
busy trying to save the airplane, or the ICM wasn't working too well)
didn't answer. The Nav got nervous & punched out, right near one of
the Base Rescue helicopters, which scooped him up & ran for home.
In the meantime, the Pilot got things under control, & managed to get
it on the ground at this Alaskan base. As he clumb down teh ladder,
he was met by the irate Nav, who was screaming at him "Why didn't you
tell me where we were! I'm teh Navigator, dammit, and I have a right
to know!"

Whoops. Senility has hit me again. Thanks Pete. Don't know what I was
thinking of. Of course you're right. That's why I needed Herk in the Nav
seat!!!!

As for the story. I'll try to check that out next month when I go to the
B-58 Hustler reunion at Fort Worth on June 4th, 5th, & 6th. It's at the
Green Oaks Inn. Stop by and I'll buy you a beer..

Darrell

B-58 Hustler History: http://members.cox.net/dschmidt1/
-

"Arie Kazachin" wrote in message
...
In message M7Mqc.31369$Md.30236@lakeread05 - "Darrell"
writes:

I think that value should be 100 ft/sec. Mach one is about 600 Knots = 1
NM/Min. One NM = 6,000'. Divide 6,000 by 60 (seconds in a minute) and
you
get 100, not 1,000.


I think you made a mistake at the very beginning:

600 knots = 600 MN/Hour = 600 NM/3600 Sec = 1/6 NM/Sec = 6000/6 ft/Sec =
= 1000 ft/Sec.

BTW, I think at sea level Mach 1 is around 660 Knots (at some "average"
temperature).

I fall on my sword! I screwed the pooch on that one. The 600 knot/mach 1
value worked pretty well for us in the Hustler since we couldn't go mach 1
at sea level (legally). We were limited to the most restrictive of 600 KIAS
/ Mach 2 / +115 C RAT. Although we had "momentary" limits higher.

Mike came back with:
Oops!

The above question should read, "...turn around and fly back to
airport "A" now with a 20 mph tailwind at the same TAS."

Glad you made that correction, I was still orbiting "B"

Rick

(OXMORON1) wrote:

Mike came back with:
Oops!

The above question should read, "...turn around and fly back to
airport "A" now with a 20 mph tailwind at the same TAS."

Glad you made that correction, I was still orbiting "B"

Heh. But now that you've flown back to "A" and landed, in order to
get the cigar and bucket of your fave drink you have to hazard an
answer to the question.

Rick

No, you are exposed to the headwind for a longer time. Any wind from any
direction will increase your round trip time. Al (a very old flight
instructor)

"Mike Marron" wrote in message
...
Mike Marron wrote:

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....)


Oops!

The above question should read, "...turn around and fly back to
airport "A" now with a 20 mph tailwind at the same TAS."

In other words, 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 "A" 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?

Mike Marron wrote:
Oops!

The above question should read, "...turn around and fly back to
airport "A" now with a 20 mph tailwind at the same TAS."

In other words, 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 "A" 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?

Okay, I'll bite.

Looks like the no-wind solution is 4 hours, the headwind/tailwind
solution is 4.17 hours.

Just in case I win, I prefer Lagavulin 16. I'll skip the seegar.


Jeff