gadget : airspeed!

Ron Hardin said:

Windscribe ultrasonic wind meter gives you _something to root for_
when you're heading into a strong wind. It velcro's on handlebar, good
to 150 mph, seems to register light winds (les than 1 mph) too.

I got mine here http://www.celestaire.com/catalog/products/3806.html

Records current, smoothed, average, max, min. Also temperature
and wind chill, if you want. (I already have a thermometer on the
handlebars.)

I'm not sure how reliable the velcro mounting is but it's worked so
far. I put it on a bar-end until I figure out which other gadget
it replaces.

Dear Ron,

My family will have cause to regret this when they ask what
toy I want for Christmas.

Thanks!

Carl Fogel

Ron Hardin said:

Windscribe ultrasonic wind meter gives you _something to root for_
when you're heading into a strong wind. It velcro's on handlebar, good
to 150 mph, seems to register light winds (les than 1 mph) too.

I got mine here http://www.celestaire.com/catalog/products/3806.html

Records current, smoothed, average, max, min. Also temperature
and wind chill, if you want. (I already have a thermometer on the
handlebars.)

I'm not sure how reliable the velcro mounting is but it's worked so
far. I put it on a bar-end until I figure out which other gadget
it replaces.

It seems to register about 10% low on the handlebars, compared to the GPS,
in still air. That makes sense, actually, if you consider you probably set up
a considerable bow wave; so it's in a 2 mph tailwind if you're doing 20 mph from
you pushing still air ahead of you. I'll have to check it by putting it on a long stick
to see what it reads.

I imagine it has an oscillator, and taps off an I and Q version, and multiplies these
by the sound received at the end of its short wind tube from a transmitter at the
other end; the phase angle gives the wind speed. It doesn't even have to sample
very fast. It's not likely to be miscalibrated.

So: add the wind speed to a tenth of itself on the handlebars from the bow wave effect.
--
Ron Hardin
[email hidden]

On the internet, nobody knows you're a jerk.

Ron Hardin said:

It seems to register about 10% low on the handlebars, compared to
the GPS, in still air. That makes sense, actually, if you
consider you probably set up a considerable bow wave; so it's in a
2 mph tailwind if you're doing 20 mph from you pushing still air
ahead of you. I'll have to check it by putting it on a long stick
to see what it reads.

Maybe it's reading in knots rather than mph. That would make it about
13% low.

--
Ray Heindl
(remove the Xs to reply to: [email hidden])

Ray Heindl said:

Ron Hardin said:

It seems to register about 10% low on the handlebars, compared to
the GPS, in still air. That makes sense, actually, if you
consider you probably set up a considerable bow wave; so it's in a
2 mph tailwind if you're doing 20 mph from you pushing still air
ahead of you. I'll have to check it by putting it on a long stick
to see what it reads.

Maybe it's reading in knots rather than mph. That would make it about
13% low.

It has the kt. option I think, but it's mph in this case. There's no
real surprise that there's a bow wave extending to the handlebars
though, unless you're riding supersonic.

I need the combination of still air and light to try it farther away
from the bicycle and see what happens.
--
Ron Hardin
[email hidden]

On the internet, nobody knows you're a jerk.

Ron Hardin said:

Ray Heindl said:

Ron Hardin said:

It seems to register about 10% low on the handlebars, compared to
the GPS, in still air. That makes sense, actually, if you
consider you probably set up a considerable bow wave; so it's in a
2 mph tailwind if you're doing 20 mph from you pushing still air
ahead of you. I'll have to check it by putting it on a long stick
to see what it reads.

Maybe it's reading in knots rather than mph. That would make it about
13% low.

It has the kt. option I think, but it's mph in this case. There's no
real surprise that there's a bow wave extending to the handlebars
though, unless you're riding supersonic.

I need the combination of still air and light to try it farther away
from the bicycle and see what happens.

HEY you might be right. It turned on today with a little kt in the corner,
maybe it got kicked off mph.
--
Ron Hardin
[email hidden]

On the internet, nobody knows you're a jerk.

Dear Ron,

Is it possible that it is not a bow wave but rather that the handle bars
are slowing down the air that the back end of the tube is in?

To a casual and untrained novice like me it would appear that this could
cause a pressure gradient across the tube that might slow the air's progress
through the chamber.

Dave Reckoning

"Ron Hardin" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Ron Hardin said:

Windscribe ultrasonic wind meter gives you _something to root for_
when you're heading into a strong wind. It velcro's on handlebar, good
to 150 mph, seems to register light winds (les than 1 mph) too.

I got mine here http://www.celestaire.com/catalog/products/3806.html

Records current, smoothed, average, max, min. Also temperature
and wind chill, if you want. (I already have a thermometer on the
handlebars.)

I'm not sure how reliable the velcro mounting is but it's worked so
far. I put it on a bar-end until I figure out which other gadget
it replaces.

It seems to register about 10% low on the handlebars, compared to the GPS,
in still air. That makes sense, actually, if you consider you probably
set up
a considerable bow wave; so it's in a 2 mph tailwind if you're doing 20
mph from
you pushing still air ahead of you. I'll have to check it by putting it
on a long stick
to see what it reads.

I imagine it has an oscillator, and taps off an I and Q version, and
multiplies these
by the sound received at the end of its short wind tube from a transmitter
at the
other end; the phase angle gives the wind speed. It doesn't even have to
sample
very fast. It's not likely to be miscalibrated.

So: add the wind speed to a tenth of itself on the handlebars from the bow
wave effect.
--
Ron Hardin
[email hidden]

On the internet, nobody knows you're a jerk.

Ron Hardin said:

There's no
real surprise that there's a bow wave extending to the handlebars
though, unless you're riding supersonic.

I've occasionally had a butterfly ride in my bow wave, fluttering
effortlessly several inches from my face. This can go on for several
seconds. As soon as it moves out of the bow wave, though, it quickly
retreats off the back.

--
terry morse Palo Alto, CA http://bike.terrymorse.com/

It's good in still air. There's another effect I think in a headwind,
namely that the wind down at the handlebar level is a good deal less
than the wind hitting the top of your body. Anyway it reads
remarkably low, namely an airspeed of 20mph reducing me to 10mph
ground speed.

But I can go 20mph is still air, so half my power is unaccounted for;
and the wind seems a lot stronger than 10 mph additional.

Sure enough, bending way down, the roar in my ears declines a good
deal as I approach the handlebar level.

(I can't ride that way because, temporarily, the wind speed meter
is occupying a bar end that I'd need to grip.)

Ie., there's a good wind shear on the ground going up, when there's
wind.

In still air, the effect isn't there, and the reading doesn't depend
on height.
--
Ron Hardin
[email hidden]

On the internet, nobody knows you're a jerk.

On Sat, 16 Oct 2004 23:12:08 GMT, Ron Hardin <[email hidden]>
scribbled:

Quoted message said:

It's good in still air. There's another effect I think in a headwind,
namely that the wind down at the handlebar level is a good deal less
than the wind hitting the top of your body. Anyway it reads
remarkably low, namely an airspeed of 20mph reducing me to 10mph
ground speed.

But I can go 20mph is still air, so half my power is unaccounted for;
and the wind seems a lot stronger than 10 mph additional.

Sure enough, bending way down, the roar in my ears declines a good
deal as I approach the handlebar level.

(I can't ride that way because, temporarily, the wind speed meter
is occupying a bar end that I'd need to grip.)

Ie., there's a good wind shear on the ground going up, when there's
wind.

In still air, the effect isn't there, and the reading doesn't depend
on height.

Well you do know what this all means, don't you?

Helmet mount!

You'll be the envy of motorists everywhere with your majestic
ornamentation!

-Slash
--
"Ebert Victorious"
-The Onion