ridecamp@endurance.net: Wind - effect on your horses performance

Wind - effect on your horses performance

Niccolai Murphy and Pat Hlavin (hlurphy@socal.wanet.com)
Mon, 28 Apr 1997 06:58:49 -0700

Hal and I were out for a bit of excercise and is apt to happen one's
mind wanders since the tranportation is on auto pilot as the trail has
been well travelled and there is not much for the rider to do but
monitor the gauges and adjust the throttle from time to time. It was a
little breezy that day and I started thinking about the thread on
ridecamp sometime ago about the effect of wind on effort required by
horses.

So I worked the following table out (it's approximate since Roger didn't
think to put a calculator on the hrm and I had to work out some
conversion factors from scratch and can only retain tow or three
significant digits). I met a ridecamper (alifarr and jnr) out on the
trail that day and nearly didn't know it as I was in the middle of one
of the calculations.

This is based on an 1100 lb horse (Hal) with the aerodynamics of me on
him (estimated based on a 16.5h horse) and headwind only. I've put it in
terms of slope so it's easy to understand. I.e. this windspeed condition
is approximately equivalent to this slope both with the horse doing 5 or
10 miles an hour.....

For Hal and me travelling at 5 mph....

A wind speed of 30 mph is the same as climbing an 8 degree hill.
A wind speed of 40 mph is the same as climbing a 18 degree hill.
A wind speed of 50 mph is the same as climbing a 35 degree hill.

For Hal and me travelling at 10 mph....

A wind speed of 30 mph is the same as climbing a 12 degree hill.
A wind speed of 40 mph is the same as climbing a 25 degree hill.
A wind speed of 50 mph is the same as climbing a 45 degree hill.

For those of you used to thinking in terms of slope ratios, 1/10 is
about 6 degrees and 1/5 is about 11 degrees, 1/1 is 45 degrees.

So if that horse seems to get tired rather quickly heading into wind you
have an idea as to how hard he's working. Aerodynamics is key. I imagine
crouching down will help him out alot as will tucking in all those drag
inducing clothings, hats etc, just like the bikers do. I didn't have the
brain power to do a sensitvity analysis on the effect of horse size, ran
out of memory just remembering the results.

It would probably be a large improvement to a thread mill to put it in
an open ended wind tunnel. It would allow the horse to work higher rates
at lower ground speed (lower impact) and have cooling effects at the
same time. Since the effect need not be exact (as in a calibrated wind
tunnel) this should be quite low cost and easy to construct (if noisy).

-- 
Nicco Murphy, San Diego County 'Open the bay door, please, Hal'

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