Clearly metric is a superior system for most expressions
of measurement, but it seems surprisingly inefficient
for flying (especially soaring) in it's current form,
which brings me to my question(s).
Why do metric variometers read in m/s, instead of kph
when the metric airspeed is in kph? Would it not make
more sense to use kph on the vario too so quick mental
L/D calculations could be done (for those who do not
use a flight computer etc to think for them)?
After doing a little homework, I figured out a 5 m/s
is 18kph (1m/s is 3.6 kph). If I used metric to fly
(I'm just plane knots) I would much rather have a vario
that went up/down to 20kph, and was hash marked on
single kilometers with numbers every 5th hash mark
for the main vario.
For a weak lift unit it would be hash marked for 1/5
kilometers but numbered every whole kilometer up/down
to 5kph.
Strong lift versions would be up/down to 30 or 40kph,
hashed every second kilometer and numbered every 5th
hash mark...Just a thought, but makes me curious.

Paul Hanson
"Do the usual, unusually well"--Len Niemi

Paul Hanson wrote:
> Why do metric variometers read in m/s, instead of kph
> when the metric airspeed is in kph? Would it not make
> more sense to use kph on the vario too so quick mental
> L/D calculations could be done (for those who do not
> use a flight computer etc to think for them)?

Well, altitude is usually measured in meters, and meters/second is the
preferred SI unit for speed. Which does bring up a related mystery.
When I was first flying gliders in the northeast US from the late 60s
through the mid 70s, pretty much all of the ASIs were in MPH and the
varios were in FPM. When I restarted flying gliders in California
during the late 80s, pretty much all of the ASIs and varios were in
knots. Was this a regional thing, or did some sort of cataclysmic shift
take place while I was off doing other silly things?

Marc

Because 1 or 2 km/hour is really slow, but 1 or 2 meters per second is
not. (Imagine the ASI in meters/second.)

At 00:18 15 September 2007, Marc Ramsey wrote:
>Paul Hanson wrote:
>> Why do metric variometers read in m/s, instead of
>>kph
>> when the metric airspeed is in kph? Would it not make
>> more sense to use kph on the vario too so quick mental
>> L/D calculations could be done (for those who do not>>
>>>>use a flight computer etc to think for them)?
>
>Well, altitude is usually measured in meters, and meters/second
>is the
>preferred SI unit for speed. Which does bring up a
>related mystery.
>When I was first flying gliders in the northeast US
>from the late 60s
>through the mid 70s, pretty much all of the ASIs were
>in MPH and the
>varios were in FPM. When I restarted flying gliders
>in California
>during the late 80s, pretty much all of the ASIs and
>varios were in
>knots. Was this a regional thing, or did some sort
>of cataclysmic shift
>take place while I was off doing other silly things?
>
>Marc

Not too cataclysmic. Somebody was smart enough along
the way to realize that 100fpm was almost exactly 1
knot. Plus, since one degree of latitude was a nautical
mile it only made sense to use knots for vertical and
horizontal motion to reduce cockpit workload in the
days before the electronic flight computer (I learned
some of this from a Derek Pigot book). It was actually
a worse situation than that here in the US, before
the fpm/mph days, when most varios here were expressed
in fps and airspeeds in mph which made for even more
math that was very avoidable (there are still a lot
of archaic instruments used, reading in silly mph and
fpm and even fps; old habits die hard) This is why
I am so baffled at m/s vs kph in a metric cockpit.
To get L/D you need to multiply your m/s vertical speed
by 3.6 to get kph before you can divide it into your
airspeed. The altitude thing is no problem whether
it is expressed in m or km, as that is a mere decimal
place switch with no real math involved, so turning
that into useful range on a map is no problem-once
you have your L/D figured.
Since m/s is the SI for speed, than why kph on the
airspeed? I'm not hung up on m/s vs kph, just the fact
that the ASI and vario should be in the same units
for quick number crunching during X/C. A m/s airspeed
would serve the same purpose with current metric varios
that kph varios would serve with current metric airspeeds.
Altimeters can stay in m without affecting workload.

Paul Hanson
"Do the usual, unusually well"--Len Niemi

Actually, I think it's one minute of latitude equals a nautical mile - works
great at a chart table with dividers but not much use in a glider cockpit.

I don't think vario units make much difference - up is good, more up is
better on any vario. Most varios aren't all that accurate anyway. Airspeed
units are more critical but most pilots just use the colored arcs and the
STF audio from the vario.

I've never used a vario in knots and an airspeed in knots to figure the d/h
ratio. The electronic gadgets do that if you are interested.

Now altimeters in meters are a pain. With 3200' per rev on the big hand how
do you know it isn't stuck?

BD


"Paul Hanson" > wrote in message
...
> At 00:18 15 September 2007, Marc Ramsey wrote:
>>Paul Hanson wrote:
>>> Why do metric variometers read in m/s, instead of
>>>kph
>>> when the metric airspeed is in kph? Would it not make
>>> more sense to use kph on the vario too so quick mental
>>> L/D calculations could be done (for those who do not>>
>>>>>use a flight computer etc to think for them)?
>>
>>Well, altitude is usually measured in meters, and meters/second
>>is the
>>preferred SI unit for speed. Which does bring up a
>>related mystery.
>>When I was first flying gliders in the northeast US
>>from the late 60s
>>through the mid 70s, pretty much all of the ASIs were
>>in MPH and the
>>varios were in FPM. When I restarted flying gliders
>>in California
>>during the late 80s, pretty much all of the ASIs and
>>varios were in
>>knots. Was this a regional thing, or did some sort
>>of cataclysmic shift
>>take place while I was off doing other silly things?
>>
>>Marc
>
> Not too cataclysmic. Somebody was smart enough along
> the way to realize that 100fpm was almost exactly 1
> knot. Plus, since one degree of latitude was a nautical
> mile it only made sense to use knots for vertical and
> horizontal motion to reduce cockpit workload in the
> days before the electronic flight computer (I learned
> some of this from a Derek Pigot book). It was actually
> a worse situation than that here in the US, before
> the fpm/mph days, when most varios here were expressed
> in fps and airspeeds in mph which made for even more
> math that was very avoidable (there are still a lot
> of archaic instruments used, reading in silly mph and
> fpm and even fps; old habits die hard) This is why
> I am so baffled at m/s vs kph in a metric cockpit.
> To get L/D you need to multiply your m/s vertical speed
> by 3.6 to get kph before you can divide it into your
> airspeed. The altitude thing is no problem whether
> it is expressed in m or km, as that is a mere decimal
> place switch with no real math involved, so turning
> that into useful range on a map is no problem-once
> you have your L/D figured.
> Since m/s is the SI for speed, than why kph on the
> airspeed? I'm not hung up on m/s vs kph, just the fact
> that the ASI and vario should be in the same units
> for quick number crunching during X/C. A m/s airspeed
> would serve the same purpose with current metric varios
> that kph varios would serve with current metric airspeeds.
> Altimeters can stay in m without affecting workload.
>
> Paul Hanson
> "Do the usual, unusually well"--Len Niemi
>
>

Paul Hanson wrote:

> Not too cataclysmic. Somebody was smart enough along
> the way to realize that 100fpm was almost exactly 1
> knot. Plus, since one degree of latitude was a nautical
> mile it only made sense to use knots for vertical and
> horizontal motion to reduce cockpit workload in the
> days before the electronic flight computer (I learned
> some of this from a Derek Pigot book). It was actually
> a worse situation than that here in the US, before
> the fpm/mph days, when most varios here were expressed
> in fps and airspeeds in mph which made for even more
> math that was very avoidable (there are still a lot
> of archaic instruments used, reading in silly mph and
> fpm and even fps; old habits die hard)

I don't dispute the abstract benefits of having the vario and airspeed
in the same units. As a practical matter, it isn't much use. Having
the airspeed in knots does help with manual navigation using sectionals.
I have never, however, done any L/D calculations based on vario
readings, and I don't know of anyone else who does. In fact, flight
computers and software do not use instantaneous (or average) vario
readings for navigation or final glide calculations, the vario is only
used to determine speed to fly.

So, the question still remains, why did the US gliding community make a
relatively quick shift from MPH and FPM to knots, when just about
everything else happens so slowly?

Marc

On Sep 14, 10:42 pm, Marc Ramsey > wrote:
....
> So, the question still remains, why did the US gliding community make a
> relatively quick shift from MPH and FPM to knots, when just about
> everything else happens so slowly?
>
> Marc

The entire US light plane community did it, not just gliding. And the
only real difference was the airspeed indicator. A vario marked in
100's of feet/min can be read as knots, they could have been changed
just by re-painting the face plate :-)

Why it was done is something that I am not sure about, but probably
the FAA pushed aircraft manufacturers to standardize on knots. FAA
regulations all reference knots, not mph.

Todd Smith
3S

On Sep 14, 8:27 pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> Actually, I think it's one minute of latitude equals a nautical mile - works
> great at a chart table with dividers but not much use in a glider cockpit.

I would use my thumb and index finger on a sectional chart to measure
distance all the time. Good enough considering the uncertainty of the
airmass we fly in.

Using NM and feet altitude also makes the E-6B wizz wheel into an
instant glide computer. Just put altitude vs. distance and the arrow
points to the glide ratio. Do this every few miles and you can see a
trend - constant or decreasing and you can probably make it.

Also, 20:1 and 30:1 are useful numbers for most sailplanes. An ASK-21
will most likely do 20:1 and an ASW-20 will do 30:1 (though I used to
do 20:1 when over rough terrain or expecting strong sink). So, take
the distance in NM and multiply by 200 and you have 30:1. Multiply by
300 and you have 20:1. Granted, this would be just as easy in metric
units, but not the map measurements.

Someday, I just might have a complete electrical failure... and it's
nice to have a few mental tricks available.

-Tom

toad wrote:
> On Sep 14, 10:42 pm, Marc Ramsey > wrote:
> ...
>> So, the question still remains, why did the US gliding community make a
>> relatively quick shift from MPH and FPM to knots, when just about
>> everything else happens so slowly?
>>
>> Marc
>
> The entire US light plane community did it, not just gliding. And the
> only real difference was the airspeed indicator. A vario marked in
> 100's of feet/min can be read as knots, they could have been changed
> just by re-painting the face plate :-)

All the airplanes I've flown use MPH, but the youngest one was built in
the 70s. I need to experience something newer, one of these days...

> Why it was done is something that I am not sure about, but probably
> the FAA pushed aircraft manufacturers to standardize on knots. FAA
> regulations all reference knots, not mph.

That does explain the change in airspeed units, the change to knots on
the vario still seems a bit "radical" for glider pilots to pull it off
that quickly...

Marc

Does this have something to do with US pilots' copying
the panels of the Europeans, who were winning big time?

At 03:30 15 September 2007, Marc Ramsey wrote:
<snip>
>
>That does explain the change in airspeed units, the
>change to knots on
>the vario still seems a bit 'radical' for glider pilots
>to pull it off
>that quickly...
>
>Marc
>

Nyal Williams wrote:

> At 03:30 15 September 2007, Marc Ramsey wrote:
> <snip>
>> That does explain the change in airspeed units, the
>> change to knots on
>> the vario still seems a bit 'radical' for glider pilots
>> to pull it off
>> that quickly...
> Does this have something to do with US pilots' copying
> the panels of the Europeans, who were winning big time?

Europeans were using knots, not m/s? Now that's weird! There was a
transition period, when you could order a Ball vario (and probably other
US varios) in fpm or knots. The only difference was the label - the
vario, including markings, was otherwise identical.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

U¿ytkownik "Paul Hanson" >
napisa³ w wiadomo¶ci

> Why do metric variometers read in m/s, instead of kph
> when the metric airspeed is in kph? Would it not make
> more sense to use kph on the vario too so quick mental
> L/D calculations could be done (for those who do not
> use a flight computer etc to think for them)?

And why do english vaariometers read in ft/min, when the english airspeed is
in knots?

multiply the m/s by 4, and then reduce the result by 1/10 and you will get
the exact value in km/h if you need to.

Eric Greenwell wrote:
> The only difference was the label - the
> vario, including markings, was otherwise identical.

Yes, my understanding is that (e.g. from Winter) the vario is the same
with alternative label plates, 1,000 fpm = 10 kt = 5 m/s (within 1%).

At 11:42 15 September 2007, MacIek wrote:
They are in knots. Although I would guess that most
people think of the climb rate as hundreds of feet
per minute. 1kt is 100' per min.
>
>And why do english vaariometers read in ft/min, when
>the english airspeed is
>in knots?
>
>multiply the m/s by 4, and then reduce the result by
>1/10 and you will get
>the exact value in km/h if you need to.
>
>
>
>

On Sep 14, 9:27?pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> Actually, I think it's one minute of latitude equals a nautical mile - works
> great at a chart table with dividers but not much use in a glider cockpit.
>


Bill, It's one minute of LONGATUDE that equals a nautical mile.
minutes of latitude vary in spacing depending how far north or south
they go. Just got my Navigator wings, so I guess I can correct
you. :-)

-EX

Yikes! What are you going to be navigating?

Go north or south one nautical mile, and you have moved a minute of
latitude.

Move a minute of longitude, and you have moved east or west, and the
distance varies how far north or south you are.




Mitch wrote:
> On Sep 14, 9:27?pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>> Actually, I think it's one minute of latitude equals a nautical mile - works
>> great at a chart table with dividers but not much use in a glider cockpit.
>>
>
>
> Bill, It's one minute of LONGATUDE that equals a nautical mile.
> minutes of latitude vary in spacing depending how far north or south
> they go. Just got my Navigator wings, so I guess I can correct
> you. :-)
>
> -EX
>

Mitch wrote:
> On Sep 14, 9:27?pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>> Actually, I think it's one minute of latitude equals a nautical mile - works
>> great at a chart table with dividers but not much use in a glider cockpit.
>>
>
>
> Bill, It's one minute of LONGATUDE .....
> Just got my Navigator wings, so I guess I can correct you. :-)

Then why don't ya know how to spell "Longitude"? :-)

Tony V.

On Sep 15, 11:51?am, Tony Verhulst > wrote:
> Mitch wrote:
> > On Sep 14, 9:27?pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
> >> Actually, I think it's one minute of latitude equals a nautical mile - works
> >> great at a chart table with dividers but not much use in a glider cockpit.
>
> > Bill, It's one minute of LONGATUDE .....
> > Just got my Navigator wings, so I guess I can correct you. :-)
>
> Then why don't ya know how to spell "Longitude"? :-)
>
> Tony V.

Both points above, absolutely correct by Tony and Greg. LOL It was a
LONG night last night, so I'm gonna have to eat crow in public on this
one. It has been a while since I have actually gotten a set of
dividers out. We always measured mileage by spanning our dividers
north and south along a line of longitude which would be measuring
latitude. The misspelling...I blaim on the fact that my spell checker
does not correct words in all caps. :-P I'm gonna go crawl in a hole
now, and continue recovery from my hangover and prevent future idiotic
postings! :-) see ya!

At 17:06 15 September 2007, Mitch wrote:
>On Sep 15, 11:51?am, Tony Verhulst wrote:
>> Mitch wrote:
>> > On Sep 14, 9:27?pm, 'Bill Daniels' wrote:
>> >> Actually, I think it's one minute of latitude equals
>>>>a nautical mile - works
>> >> great at a chart table with dividers but not much
>>>>use in a glider cockpit.
>>
>> > Bill, It's one minute of LONGATUDE .....
>> > Just got my Navigator wings, so I guess I can correct
>>>you. :-)
>>
>> Then why don't ya know how to spell 'Longitude'? :-)
>>
>> Tony V.
>
>Both points above, absolutely correct by Tony and Greg.
> LOL It was a
>LONG night last night, so I'm gonna have to eat crow
>in public on this
>one. It has been a while since I have actually gotten
>a set of
>dividers out. We always measured mileage by spanning
>our dividers
>north and south along a line of longitude which would
>be measuring
>latitude. The misspelling...I blaim on the fact that
>my spell checker
>does not correct words in all caps. :-P I'm gonna
>go crawl in a hole
>now, and continue recovery from my hangover and prevent
>future idiotic
>postings! :-) see ya!
>
Don't BLAME you, Mitch! <grin>

Nyal

On Sat, 15 Sep 2007 10:03:24 -0700, Mitch > wrote:

>On Sep 15, 11:51?am, Tony Verhulst > wrote:
>> Mitch wrote:
>> > On Sep 14, 9:27?pm, "Bill Daniels" <bildan@comcast-dot-net> wrote:
>> >> Actually, I think it's one minute of latitude equals a nautical mile - works
>> >> great at a chart table with dividers but not much use in a glider cockpit.
>>
>> > Bill, It's one minute of LONGATUDE .....
>> > Just got my Navigator wings, so I guess I can correct you. :-)
>>
>> Then why don't ya know how to spell "Longitude"? :-)
>>
>> Tony V.
>
>Both points above, absolutely correct by Tony and Greg. LOL It was a
>LONG night last night, so I'm gonna have to eat crow in public on this
>one. It has been a while since I have actually gotten a set of
>dividers out. We always measured mileage by spanning our dividers
>north and south along a line of longitude which would be measuring
>latitude. The misspelling...I blaim on the fact that my spell checker
>does not correct words in all caps. :-P I'm gonna go crawl in a hole
>now, and continue recovery from my hangover and prevent future idiotic
>postings! :-) see ya!

Well, to get all pedantic, there have been several definitions of the
nautical mile, one of which was one minute of longitude at the
equator -- which has the advantage of being unambiguous since the
equator is a circle to very high precision. If you define it as a
minute of latitude you still have to specify the latitude where you
make the measurement, because the earth is not exactly spherical;
England defined it for a time as one minute of latitude measured at
the latitude of London.

Today it's simply defined as exactly 1852 meters, but "the arc length
subtended by one minute of latitude" is just peachy for navigational
purposes.

rj

On Sep 16, 2:08 am, Ralph Jones > wrote:
<snip>
>
> Well, to get all pedantic, there have been several definitions of the
> nautical mile, one of which was one minute of longitude at the
> equator -- which has the advantage of being unambiguous since the
> equator is a circle to very high precision. If you define it as a
> minute of latitude you still have to specify the latitude where you
> make the measurement, because the earth is not exactly spherical;
> England defined it for a time as one minute of latitude measured at
> the latitude of London.
>
> Today it's simply defined as exactly 1852 meters, but "the arc length
> subtended by one minute of latitude" is just peachy for navigational
> purposes.
>
We got around to 'the arc length subtended by one minute of a great
circle' when I did a maritime navigation class back in the mid-90s.
It's a definition which is not quite correct, but resolves the
differences between lines of latitude & longitutude for this purpose.

I recalled a one-page article in Soaring magazine that promoted the
idea of using knots for vertical speed on the variometer. I finally
found it in the Soaring magazine index: June 1963. The author used a
pseudonym ("Sinbad"). I assume the soaring world was moving in that
direction anyway but this was the first our little group in the
midwest had heard of this idea. Within a few years, certainly by 1970,
everyone seemed to be switching over to knots both in conversation as
well as what they ordered on new instrument dials. It was a change for
me from feet per second (on a Cosim pellet vario--anyone remember
those?), meters per second (what the Winters of that era used), and
feet per minute (various varios of that day plus all of the light
aircraft rate-of-climbs we stuck into our glider panels as backups,
the most famous of which was the "Memphis" ROC that came out of Beech
Bonanzas from a decade or two earlier).

Chip Bearden
ASW 24 "JB"
USA

I have been really distressed since returning to Alaska from St.
Auban a few years ago when I had to give up my very easy metric 20/1
glide calculator system for 1/250,000 maps, i.e., my right hand with
four fingers, and a metric altimeter.

Life should be so easy here. Here's why:

A hand's width, just above the knuckles, is 20k on my marked up French
road map commonly used for soaring in the Sud Alpes. So at 20/1, you
need 1,000 meters to glide your hand's width across the map. Two
fingers on the map to a safety field requires 500 meters plus pattern
entry height which I had already marked on my map. All I had to do
was to count my fingers to the landing field, multiply by 250, and
add the pattern entry height to know whether I had to buy a new glider
or not.

It doesn't get much simpler than that which is fortunate for me
because I can't do much more complicated calculations in my head,
especially when I am stressing because I am low and lost in the
mountains in a foreign country where the only people who speak worse
French than I do are my fellow Alaskans Jeff Banks and Ed Kornfield
who also flew from St. Auban. No GPS, PDAs, or complicated glide
calculators (formerly known as prayer wheels in the old days of
circular slide rules), just lay your hand on the map, count your
fingers, and add.

One note on French altimeters: In addition to being marked in meters,
the French, rather sensibly when you think about it, have the -0- mark
on the altimeter on the bottom of the dial and you go up from there.

Pete Brown
Anchorage


> Also, 20:1 and 30:1 are useful numbers for most sailplanes. An ASK-21
> will most likely do 20:1 and an ASW-20 will do 30:1 (though I used to
> do 20:1 when over rough terrain or expecting strong sink). So, take
> the distance in NM and multiply by 200 and you have 30:1. Multiply by
> 300 and you have 20:1. Granted, this would be just as easy in metric
> units, but not the map measurements.
>
> Someday, I just might have a complete electrical failure... and it's
> nice to have a few mental tricks available.
>
> -Tom

Well, actually, it is!

I was taught this trick years ago----glad to see it works in "metricland"
also.

One finger width on a USA Sectional Chart 1:500,000 is (approximately) 5 NM
One Nautical Mile is (approximately) 6000 ft

So--at 30:1 (200 ft/mi), one finger is about 1000 ft required.
At 20:1(300 ft/mi), one finger is about 1500 ft required.

Add in pattern altitude, and there you are!

Hartley Falbaum
USA "KF"


> wrote in message
ups.com...
>I have been really distressed since returning to Alaska from St.
> Auban a few years ago when I had to give up my very easy metric 20/1
> glide calculator system for 1/250,000 maps, i.e., my right hand with
> four fingers, and a metric altimeter.
>
> Life should be so easy here. Here's why:
>