From: "Matt Weaver" < >        (see also Proposed Method)

To:

Subject: IHPVA Record Rules and Battle Mountain - Summary / Recent Conclusions

Date: Thu, 12 Sep 2002 13:15:02 -0700

I wish to thank many lately for the much-needed discussions and personal
feedback on the wind rules, given concerns that loom of potential undue
disadvantage of racers at the upcoming event at Battle Mountain, NV.  Thank
you in particular, Theo Schmidt, Bill Gaines, Paul Gracey, Martin
Staubach....

After pondering everyone's feedback, I came to a few conclusions you may
wish to note.  I've grouped them as follows and elaborate briefly on each.

    - "Simple" versus "Advanced" Approaches on Wind Measurements
    - Clarification of my Original Wind Rule Proposal
    - "Aero Pushing" / Pursuit Vehicle Distance
    - "Back Up" Runs
    - Wind and "HPV" versus "Ambient Energy" ("AEV?") Racing

Lastly, I have some commentary on the recent dialogs, containing a few
snippets of previous discussions spanning multiple emails.  The following
are discussed:

    - THE "RIGHT" WIND ANGLE
    - WIND ANGLE RELATIVE TO "COURSE" OR THE "VEHICLE"?
    - SIMPLIFIED WIND RULES?
    - LAND VEHICLE SAILING IS "ONLY IN THEORY?"
    - PERPENDICULAR AXIAL-VANE (IHPVA-TYPE) SENSORS - POTENTIALS
    - VEHICLES CAN NOT SIGNIFICANTLY BENEFIT FROM SIDEWIND?
    - "SOPHISTICATED EQUIPMENT" AND IHPVA EVENTS
    - NON-PRO EQUIPMENT FOR SURVEYING TO FIND COURSE SITES


===== "Simple" versus "Advanced" Wind Measurements =====
As for wind, I agree very much for a "simple" method that is readily
verifiable and manageable by the observers.  In all instances this should be
performed.  I do know that data-logging of entire wind histories may be very
doable and have a role in future "ambient energy" type contests.  Such would
be an "addition" to the "simple" methods.  I discuss some potentials of this
below under "PERPENDICULAR AXIAL-VANE (IHPVA-TYPE) SENSORS - POTENTIALS," as
well as under "Sophisticated Equipment...."


===== Clarification of Wind Rule Proposal =====
Discarding my "code" attempts, perhaps a simple re-wording of my original
wind proposal is in order.  It is as follows:

'For a straight course, divide the wind direction into two hemispheres.  One
hemisphere contains all "tailwinds," the other all "headwinds."  For the
"tailwind hemisphere", simply apply the existing IHPVA rules (wind speed
limited to 1.67 meters/sec).  For the "headwind hemisphere", simply
guarantee the sidewind component alone is limited to the existing IHPVA 1.67
meters/second windspeed.

This is what I intended in the rules proposal I offered months ago.  This
can be done using wind angle & wind speed, or with an axial-vane
(IHPVA-type), by simply pointing the meter directly perpendicular to the
course for ALL winds in the "headwind hemisphere."  In other words, the need
for the "axial vane" meter to point into the wind is optional if it known to
be a headwind.

The basis for this approach is elaborated in "THE "RIGHT" WIND ANGLE"
section below.

The purpose is in light of the upcoming Battle Mountain event.  It is to
eliminate the sad and probable situation of a record achievement that
additionally overcame a headwind from being rendered "illegal" and discarded
by current IPHVA wind rules.  A similar concern applies to some degree
regarding the burden of "back-up" runs (discussed below).


===== "Aero Pushing" / Pursuit Vehicle Distance =====
It was noted by Paul and others of concerns of "chase vehicle" proximity.
It is dramatically true that a "following" vehicle can actually propel a
bike, even reduce rider power requirements to zero.  The Dempsey Prize
places limits on this of 30 meters (I believe).  That is about as close as a
vehicle should dare come.  Better would be distances of 100 meters or so
(before it gets hard to even know where the bike is out front).  There
certainly needs to be a formalized IHPVA rule on this at some point as is
already the case for the Dempsey Prize.

For validation, either a course camera, or official observers on board, or
both is desirable.  I'll be utilizing "dual GPS" tracklogs thanks to a
loaner from a friend.  One GPS on the bike, one in the car, each position
recorded every second with an atomic time stamp and position good to better
than 10 meters (typically much better).  This is rather definitive.
Alternately a "wheel" position sensor (just like a cyclometer, but recording
the data, can be attached to pursuit vehicle too - see "SOPHISTICATED
EQUIPMENT" AND IHPVA EVENTS below).


===== "Back Up" Runs =====
There has been discussion of "back up runs."  In my opinion again, they once
were not required by the IHPVA, and best not be required now save a "remote"
"private" attempt for which authentication may be less certain.  Other
athletic contests, including the Olympics and various World Championship
events do not require back-ups.  For IHPVA events well documented, I do not
see a need.  If an athlete has one great heroic effort, but all others
attempts on the athlete's part are "illegal" due to wind, I would rather see
his/her achievement honored than discarded as if it didn't happen.


===== Wind and "HPV" versus "Ambient Energy" ("AEV?") Racing =====
With all this discussion of wind and the "restriction" or "non-restriction"
of it, I think it's worth noting that some very exciting "ambient energy"
racing looms around the corner (using immediate sun/wind/muscle/energy
management...).  All the "tools" are really here now for "AEV's" to be
dramatically realized.  Potential performances far exceed that of "human
power" alone, and such contests represent an exciting challenge with many
variables yet ultimately the bottom line is still simply lap time during a
race.  I find both "HPV" and "AEV" contests have a unique role.  I've been
excited to learn Paul MacCready, Theo Schmidt, and others are of like mind
on this as well.

- "HPV", Naturally will have wind and slope restrictions,
- "AMBIENT" or "AEV", will likely will not have wind or slope restrictions,
but will likely take place predominantly on closed courses.

-----
Thanks again for everyone that has recently taken the time to listen to the
issues I raised and show concern over these matters at hand.  It has been
rather exhausting (understandably) to bring it to the table since Battle
Mountain started in 2000, but so what.  I'm glad to know at this time it now
appears the IHPVA will not be needlessly bound by its rules to reject any
record achievements that may have additionally overcome "IHPVA illegal"
headwinds.  I grew rather concerned in recent weeks (as you probably know
from my recent mailings...) knowing how probable such headwinds are at the
upcoming contest at Battle Mountain 2002 which this year will involve
upwards of 10 racers from at least 4 different countries.

Back to race preparations!

Kind regards,
Matt Weaver


============PREVIOUS DIALOGS ON WIND FROM OTHERS (">" or "> >")============
Added Comments by Matt.


===== THE "RIGHT" WIND ANGLE
> But what is the "right" angle? If we follow this wording, we should define
a small
> enough angle that can make sure there is no vehicle design that can
benefit from the > given wind conditions.

The "angle" of significance is relative to the BIKE, not the course.  Since
the bikes are traveling at rather high speeds (60 to 80-MPH) compared to the
winds of concern, the wind component parallel to the bike motion has little
effect on the "angle" relative to the bike.

The perpendicular, or crosswind component predominantly determines the
"angle" relative to the bike and the "sailing" benefit.  Therefore, simply
the crosswind speed reveals rather thoroughly what sort of sailing effect a
bike may obtain.  As I noted before, there is a minimum angle within which
there is little or no benefit.  In my estimations of a number of existing
top vehicles at the speeds they go, this angle interesting corresponds to
crosswind speeds roughly equal and slightly greater than the current IHPVA
1.67 meters/second rule.  In other words - the IHPVA limit of 1.67
meters/second just happens to be pretty good for guaranteeing no propulsive
benefit of any kind from wind (except of course a tailwind).


===== ALTERNATE PROPOSALS - WIND ANGLE RELATIVE TO "COURSE" OR THE
"VEHICLE"?
> "3.3.4.B. The true wind speed may have any value if it's direction
> can be shown to not exceed 45 degrees from the direction of the
> vehicle's motion. This rule is valid only for a straight course."
>
> This is not quite the same as Matt's proposal. Reasoning see my
> answer to Martin Staubach (other mail). Alternatively the angle could
> be tightened (say 30 degrees) or the rule could be:
>
> "3.3.4.B. The true wind speed may have any value if it's direction
> can be shown to not exceed 90 degrees from the direction of the
> vehicle's motion and it's vector component at a right angle to the
> vehicle's motion not exceed 6 km/h.  This rule is valid only for a
> straight course."
>
> Maybe this is what Matt had in mind. The first rule is simpler and
> easier to measure.

See my comments about 'THE "RIGHT" WIND ANGLE' above.  I should note, my
original recommendation viewed another way is this:  Divide the wind
direction into two hemispheres.  One hemisphere contains all "tailwinds,"
the other all "headwinds."  For the "tailwind hemisphere", simply apply the
existing IHPVA rules (wind speed limited to 1.67 meters/sec).  For the
"headwind hemisphere", simply guarantee the sidewind component alone is
limited to the existing IHPVA 1.67 meters/second windspeed.

This can be done using wind angle & wind speed, or with an axial-vane
(IHPVA-type), by simply pointing the meter directly perpendicular to the
course for all winds in the "headwind hemisphere." (note - if the headwind
"switches sides" - it must be insured that the wind meter does not "count
backwards" - thus negating the wind count from wind coming from one side of
the course with the wind coming from the opposite side).


===== "SIMPLIFIED" WIND RULES?
> >The question is if there is a range of sidewind which allows sailing
> >without causing steering problems. If we could answer this question
> >with no, we would not need to restrict sidewind. In this case we
> >could keep the rules smart and simple and only restrict tail wind.
> >
> >What do you think about this radical conclusion?
>
> I'm afraid the answer is not no, but yes. Many vehicles will be able
> to take advantage of a smooth sidewind. See
>
> http://home.earthlink.net/~jameslamick/press/images_from_rna/
>
> for the picture of solar vehicles specifically designed to take
> benefit from the wind, as far as I know without using flaps, etc. Of
> course the devices shown are obviously sails, but they are not that
> different from some fairings not designed as sails.

As I comment, bear in mind I understand and respect the desire to not have
events encumbered by wind restrictions....  Some existing tricycles can
readily manage a range of winds w/o too much steering problem, so can some
bikes, and it is certainly possible to build vehicles that readily derive
more power from ambient wind than the cyclist could ever hope to produce
him/herself.  So no, I do not see such "simplifications" based on
presumptions of "steering problems" valid.  I do however see two "contests":
    - an "ambient energy" vehicle (use all the immediate
sun/wind/muscle/power management, etc... you can muster!),
    - and a pure "human powered" contest (viable bounds on wind/gravity,
etc....)

Each contest has a definite role.


===== LAND VEHICLE SAILING IS "ONLY IN THEORY?"
> >I am sure that there is not much room for a rider at top speed (an
> >maximum power) for concentration on side wind correction. That's why
> >I think it is a self minimizing problem.
> >In other words, side wind can be used for sailing in theory. But in
> >under sidewind conditions suitable for sailing I think the steering
> >problems predominate the sailing benefits.
>
> I think you are probably right for most cases.

For "sprints" at speeds approaching 80-MPH - this is arguably true with
currently existing vehicles - crosswinds are dreaded and to be avoided, and
in their presence a rider is likely to not give the intense effort a sprint
demands.  On the other hand, there are multiple tricycle configurations and
many other possibilities that I and many others could readily build.  In
time, I don't think winds will pose much of a control challenge, and will be
regarded as very beneficial in nearly all cases save a direct headwind on a
straight course.

For sustained runs like the hour - there is arguably a definite "sweet spot"
of winds in the 4-10 MPH range that are "manageable" by existing top
bikes/riders and provides a definite sailing benefit, even on a closed
course regardless of wind direction.  Given also the lower power levels of a
sustained run like the hour, the benefits of the wind power can readily
assume a greater fraction of total propulsive power than in the case of a
sprint.


===== PERPENDICULAR AXIAL-VANE (IHPVA-TYPE) SENSORS - POTENTIALS
> At 14:04 Uhr -0700 6.9.2002, Matt Weaver wrote:
> > The "axial vane" type sensors reflect
> >very precisely their parallel wind speed component alone, and are very
> >insensitive to the off-axis wind
...
> I am puzzled how to interpret this. I would have assumed that an
> unshrouded axial vane records with some function of the off-axis
> component, ideally a simple function such as the cosine.

The "parallel wind speed component" I referred to is simply the "cosine" as
you noted.  Based on conversation with Paul MacCready this is highly
accurate.  As such, with data-logging of two sensors, subsequent analysis of
the time histories of the two wind vanes can reveal a complete history of
both wind speed and direction.

The new precision event timer I'll be using to time-stamp each wheel rev can
also be utilized to synchronously log two perpendicular wind meters.  It
holds 2 megabytes of data, so there's the potential for inexpensive multiple
stand-alone "wind stations" distributed about the course.  Given the
stability of the time stamp, all the sensors can be synchronized later -
yielding a sort of "2D" map of the wind over the "duration" of an event and
over the "space" of the course.  This could be very interesting for learning
more about "ambient energy" (wind/solar) vehicle performance as such
contests grow in significance.


===== VEHICLES CAN NOT SIGNIFICANTLY BENEFIT FROM SIDEWIND?
> >I personally am sure (wich is quite subjective) that even on a
> >straight course vehicles can not significantly benefit from
> >sidewind. Correct me if you have different experience.
>
> To my knowledge and in my experience there can be a great advantage
> from sidewind, especially if this is smooth. In my own fully faired
> human/solar powered tricycle I subjectively was able to feel this.
> Also, while tranporting the vehicle on the top of a car, I was able
> to use much less motor
> power in a strong, smooth sidewind than normally.

I concur with the later statement.  Think of existing 100-MPH sailcars,
etc....  If you can't balance it, or lack advanced controls, you can add a
3rd wheel like a sailcar, etc....  The interesting thing is when the
aerodynamics are very good, as in the case of the best HPV's, the "body"
becomes the "sail" (and potentially quite dramatically at that).


===== "SOPHISTICATED EQUIPMENT" AND IHPVA EVENTS
> Thanks also for your hard work. I am a bit sceptical about
> sophisticated equipment as it is easy to incurr errors without
> noticing. By all means use the equipment, but for legal/non-legal
> wind decisions I would prefer something really simple, like the
> streamers/smoke, etc. you propose in another mail.

I agree very much for simplicity and direct observability.  With wind, given
the potential for a simple streamer/smoke to determine direction, I would
absolutely utilize it and officially note it at race time.  Wind direction
and gross "magnitude" can be plainly observed with our own senses.  On the
other hand, we do rely very much on "sophisticated equipment."  Even the
simple wind meters already used - spin much too fast to directly visually
count the revolutions - we trust the "counting mechanism" internal to the
sensor.  Likewise, the time traps are entirely automatic, and even "hand
times" with separate watches is elusive with 200 meters (over two football
fields!) being covered in little over 5 seconds.

Considering "sophisticated equipment" - I seek for independent redundant
sensors.  I was thinking this year's race - in addition to the 1 or 2
independent timing traps on the course, I will likely have (1) an on-board a
WAAS GPS, (2) every wheel revolution (about 5000 revs) recorded to a
1/32768th of a second with 1ppm stability, (3) an on-board SRM recorder
likewise recording velocity 10 times a second, (4) another WAAS GPS from a
friend in the pursuit car, (5) possible video recorder yielding about 10000
video frame "snapshots" of the run, (6) possibly more video stationary at
the trapside from the official observers showing over 150 video frames of
the bike in the 200 meter trap....  All these 7 or 8 "observations" can be
synchronized precisely by time.  All the sensors can be promptly handed over
to officials in the "stop zone" for secure management.  If they all readily
correlate, it's pretty substantiating of what happened.  I'd like to also
think two or three human "witnesses" are worth something to others, but my
experience thus far suggests otherwise.  Besides, the sensors yield data
from which scientific analysis can be performed.


===== NON-PRO EQUIPMENT FOR SURVEYING TO FIND COURSE SITES
> At 14:04 Uhr -0700 6.9.2002, Matt Weaver wrote:
> >I'm perhaps more tolerant of the 2/3% rule after doing the 2000-mile
> >kinematic survey...
...
> Certainly better instrumentation will open up more sites which have
> up to now been doubtful. I am wondering how it is possible to measure
> the altitude differences and slopes we are talking about without
> having to resort to professional survey equipment.

The "equipment" I used for the 2000-mile survey that identified Battle
Mountain was actually barometric!  It did start out as a very fancy
kinematic GPS set-up on loan from a research company (SRI), but they sold
the equipment and the rights to it shortly before I was to use it, and I was
left to my own....  I fortunately learned of, and even more fortunately
obtained a special baro sensor from Setra Systems.  It has the potential to
detect w/o hysteresis air pressure changes equivalent to less than 1 inch of
altitude.  It of course takes fancy electronics coupled with it.  The
electronics of interest were over $7000, so I designed and built them myself
and software to interface ... and it all worked!  Of course the atmospheric
pressure drifts, but if covering enough road quickly enough, that
atmospheric drift typically represents very small "false slope" values while
surveying.  Also, pressure changes simply due to vehicle speed must be
accounted for.  I resolved that successfully too.  End result was a survey
often good to 2 inches in either direction on "calm" nights.  That's very
good at 60-MPH!  On the other hand, for fun I could "observe" things like
"waves" in the atmosphere (and I'm not talking equipment noise or drift!).

Nowadays, it's arguably MUCH simpler to go course-hunting.  With the "SA
dither" removed from GPS, A cheap hand-held WAAS GPS ($150 or so), and
tracklog recordings of multiple passes on a road of interest, downloaded
with freeware (G7toWin or similar) can be accurate enough!!  Of course the
IHPVA still requires a "professional survey," but in all honesty you won't
learn anything new of significance.  Get in your car and go!  GPS tends to
be rather "coarse" in the vertical axis, as most hand-helds store the
vertical with low resolution (discretized to 1 foot increments or so).  This
is where "multiple passes" can quickly reduce that.

Another approach is to feed the full GPS data from a hand-held real-time
into a laptop computer or Palm using modestly-priced software (Gringo) and
perform post-operations on all the raw satellite readings.  Final vertical
readings can be achieved outright.  A "single pass" will get you close
enough to know whether a course is valid at all, and averaging multiple
passes can quickly refine it much further.  In such a case, you are doing
something similar to what surveyors do with GPS.  There are still some
limitations compared to what "high-end" GPS surveyor equipment can do, but
not much for this task!