AT, TAT, MAT?

I don't understand - if you add 15 minutes, what's to stop people from
trying to come in 14 minutes and 59 seconds sooner? *Doesn't that just
shift the "minimum task time" without affecting the racing (if not,
what's the logic I'm missing)?

--Noel

I'm guilty of being too obscure. A few years ago the US experimented
with the following rule. To determine your speed for scoring, we take
(Time + 15 minutes)/distance. Time still had to be greater than
minimum time.

The effect of this change is to offset the fact that you get one fast
final glide, or equivalently one fee thermal to the top of the start
gate, per flight, and therefore remove the critical importance of
finishing close to the minimum time.

For example, suppose you fly 50 mph through the air -- top of start
gate to top of last thermal -- and then do a 15 minute, 100 mph
final glide on a 2:00 hour turn area task. If you fly it perfectly and
finish in two hours, you go (50 x 1.75 + 100 x 0.25 )/2 = 56.2 mph.
If you blow it and do a 2:30 flight, you go (50 x 1.25 + 100 x 0.25) /
2.5 = 55 mph or 972 points. That is a huge difference in contest
soaring, so no wonder pilots invest in thousands of dollars of
computers.

If you add 15 minutes to each time, though, you get scored for 50 mph
in each case! The 15 minute time addition exactly offsets the one-
glide-per-flight effect and makes it unimportant how long you stay
out, so long as you end above minium time and fly fast.

I wish I could say that this was overturned by the evil conspiracy of
flight computer manufacturers. Pilot confusion and poor salesmanship
by its advocates did in a very pretty idea.

And I am not trying to revive it -- lost cause!

John Cochrane

On Oct 13, 4:25*pm, BB wrote:

I'm guilty of being too obscure. A few years ago the US experimented
with the following rule. To determine your speed for scoring, we take
(Time + 15 minutes)/distance. Time still had to be greater than
minimum time.

The effect of this change is to offset the fact that you get one fast
final glide, or equivalently one fee thermal to the top of the start
gate, per flight, and therefore remove the critical importance of
finishing close to the minimum time.

For example, suppose you fly 50 mph through the air -- top of start
gate to top of last thermal -- *and then *do a 15 minute, 100 mph
final glide on a 2:00 hour turn area task. If you fly it perfectly and
finish in two hours, you go (50 x 1.75 + *100 x 0.25 )/2 = 56.2 mph.
If you blow it and do a 2:30 flight, you go (50 x 1.25 + 100 x 0.25) /
2.5 = 55 mph * or 972 points. That is a huge difference in contest
soaring, so no wonder pilots invest in thousands of dollars of
computers.

*If you add 15 minutes to each time, though, you get scored for 50 mph
in each case! The 15 minute time addition exactly offsets the one-
glide-per-flight effect and makes it unimportant how long you stay
out, so long as you end above minium time and fly fast.

I wish I could say that this was overturned by the evil conspiracy of
flight computer manufacturers. Pilot confusion and poor salesmanship
by its advocates *did in a very pretty idea.

And I am not trying to revive it -- lost cause!

John Cochrane

OK, got it. Not sure it works in all cases (though it worked OK in a
few random-number cases I threw at it), but I understand it now. My
newbie brain works better when this is phrased "add 15 minutes at 0mph
on to the end of your flight" (this also jives with your "free
thermal" explanation, since if there's no wind your speed along the
course is effectively zero when you're thermalling straight up).
*shrug* Maybe I'm just weird.

I still don't see how this changes the problem with people coming in
under-time, if the raw time (before adding 15 minutes) still has to be
greater than the minimum task time...

BTW there's a little typo in your example numbers. The longer-flight
pilot spent 2.25 hours at 50mph, not 1.25. :-)

--Noel

On Oct 13, 4:41*pm, "noel.wade" wrote:
On Oct 13, 4:25*pm, BB wrote:





I'm guilty of being too obscure. A few years ago the US experimented
with the following rule. To determine your speed for scoring, we take
(Time + 15 minutes)/distance. Time still had to be greater than
minimum time.

The effect of this change is to offset the fact that you get one fast
final glide, or equivalently one fee thermal to the top of the start
gate, per flight, and therefore remove the critical importance of
finishing close to the minimum time.

For example, suppose you fly 50 mph through the air -- top of start
gate to top of last thermal -- *and then *do a 15 minute, 100 mph
final glide on a 2:00 hour turn area task. If you fly it perfectly and
finish in two hours, you go (50 x 1.75 + *100 x 0.25 )/2 = 56.2 mph..
If you blow it and do a 2:30 flight, you go (50 x 1.25 + 100 x 0.25) /
2.5 = 55 mph * or 972 points. That is a huge difference in contest
soaring, so no wonder pilots invest in thousands of dollars of
computers.

*If you add 15 minutes to each time, though, you get scored for 50 mph
in each case! The 15 minute time addition exactly offsets the one-
glide-per-flight effect and makes it unimportant how long you stay
out, so long as you end above minium time and fly fast.

I wish I could say that this was overturned by the evil conspiracy of
flight computer manufacturers. Pilot confusion and poor salesmanship
by its advocates *did in a very pretty idea.

And I am not trying to revive it -- lost cause!

John Cochrane

OK, got it. *Not sure it works in all cases (though it worked OK in a
few random-number cases I threw at it), but I understand it now. *My
newbie brain works better when this is phrased "add 15 minutes at 0mph
on to the end of your flight" (this also jives with your "free
thermal" explanation, since if there's no wind your speed along the
course is effectively zero when you're thermalling straight up).
*shrug* Maybe I'm just weird.

I still don't see how this changes the problem with people coming in
under-time, if the raw time (before adding 15 minutes) still has to be
greater than the minimum task time...

BTW there's a little typo in your example numbers. *The longer-flight
pilot spent 2.25 hours at 50mph, not 1.25. *:-)

--Noel- Hide quoted text -

- Show quoted text -

On Oct 13, 4:41*pm, "noel.wade" wrote:

I still don't see how this changes the problem with people coming in
under-time, if the raw time (before adding 15 minutes) still has to be
greater than the minimum task time...


Apples and oranges - the (now defunct) 15 minute rule flattened out
the points awarded as a function of time on course OVER AND ABOVE the
minimum time. It was an attempt to reverse out an implicit scoring
penalty due to the dilution of final glide speed into sustained cross-
country speed - longer flights got penalized more as the dilution
effect decreased.

The second topic has to do with flight management - being on time but
not under. The penalty for being under time is much more severe than
the hidden penalty for being over - you get marked to minimum time,
which is like averaging in zero speed for the time you are under.

Hope that makes sense to people.

9B

On Oct 13, 4:25*pm, BB wrote:
I don't understand - if you add 15 minutes, what's to stop people from
trying to come in 14 minutes and 59 seconds sooner? *Doesn't that just
shift the "minimum task time" without affecting the racing (if not,
what's the logic I'm missing)?

--Noel

I'm guilty of being too obscure. A few years ago the US experimented
with the following rule. To determine your speed for scoring, we take
(Time + 15 minutes)/distance. Time still had to be greater than
minimum time.

The effect of this change is to offset the fact that you get one fast
final glide, or equivalently one fee thermal to the top of the start
gate, per flight, and therefore remove the critical importance of
finishing close to the minimum time.

For example, suppose you fly 50 mph through the air -- top of start
gate to top of last thermal -- *and then *do a 15 minute, 100 mph
final glide on a 2:00 hour turn area task. If you fly it perfectly and
finish in two hours, you go (50 x 1.75 + *100 x 0.25 )/2 = 56.2 mph.
If you blow it and do a 2:30 flight, you go (50 x 1.25 + 100 x 0.25) /
2.5 = 55 mph * or 972 points. That is a huge difference in contest
soaring, so no wonder pilots invest in thousands of dollars of
computers.

*If you add 15 minutes to each time, though, you get scored for 50 mph
in each case! The 15 minute time addition exactly offsets the one-
glide-per-flight effect and makes it unimportant how long you stay
out, so long as you end above minium time and fly fast.

I wish I could say that this was overturned by the evil conspiracy of
flight computer manufacturers. Pilot confusion and poor salesmanship
by its advocates *did in a very pretty idea.

And I am not trying to revive it -- lost cause!

John Cochrane

The main argument against this was due to the rate = distance / time
formula being drilled into us in junior high school. Many people hated
the idea that your speed wasn't distance divided by time. Of course at
that time points were proportional to calculated speed.

Since we have now (I suspect) increased distance points to 600 and
thereby compressed scores so speed points are not necessarily pro-rata
to actual speed around the course, it might be acceptable to re-think
a form of this. While it was analytically elegant to think in terms of
the 15 minutes added in calculating speed around the course I think it
might be better to think about it in terms of how points are awarded
and leave the speed calculation alone. I realize that there are
circumstances where a slower raw speed might earn higher points than a
faster raw speed, but my recollection is that the differences are
minor and the only way this would happen is if someone took a much
longer flight than a competitor flying nearly the same speed. Making
the scoring work with the equivalent of 10 minutes added rather than
15 would likely clean up this apparent anomaly. Also, a modest
incentive not to go chase a cloud street into the next state may not
be so bad.

I would add that, while John's logic and math are absolutely correct
there is often enough going on with the weather that overrrides how
much time you do (or should) spend on course that the logic for being
just on time versus a few minutes late gets washed away like good
intentions.

Now that the government is taking John's advice and recapitalizing the
banks rather than buying their bad loans, maybe we should revisit his
soaring advice too.

My soaring season is done, so I may as well re-hash this sort of
thing.

9B

Now that the government is taking John's advice and recapitalizing the
banks rather than buying their bad loans, maybe we should revisit his
soaring advice too.


Just to set the record straight, this is a little joke from Andy.
Don't blame me for this mess of a hideous bailout and goverment
takeover of the banking system! (As if anyone ever listened to my
advice in the first place.) Ok, it's not as disastrous as having the
government buy out every bad mortgage in the country, but not by a
whole lot.

John

On Oct 16, 8:41*am, BB wrote:
Now that the government is taking John's advice and recapitalizing the
banks rather than buying their bad loans, maybe we should revisit his
soaring advice too.

Just to set the record straight, this is a little joke from Andy.
Don't blame me for this mess of a hideous bailout and goverment
takeover of the banking system! (As if anyone ever listened to my
advice in the first place.) Ok, it's not as disastrous as having the
government buy out every bad mortgage in the country, but not by a
whole lot.

John

;-)

On Oct 16, 9:40*am, wrote:
On Oct 16, 8:41*am, BB wrote:

Now that the government is taking John's advice and recapitalizing the
banks rather than buying their bad loans, maybe we should revisit his
soaring advice too.

Just to set the record straight, this is a little joke from Andy.
Don't blame me for this mess of a hideous bailout and goverment
takeover of the banking system! (As if anyone ever listened to my
advice in the first place.) Ok, it's not as disastrous as having the
government buy out every bad mortgage in the country, but not by a
whole lot.

John

;-)

In a feeble attempt to make this more glider-related:

I'd like to see the bailout architects *actually* have to bail out.
If they survive, we consider letting them stay in office... But I
can't decide if we give them a parachute or not. ;-)

Also, I believe that commercial glider operations need to lobby
congress. Many are failing or have gone into bankruptcy, and they
need the government's help to stay afloat. We keep hearing that
consumer spending is the lynchpin of our economy, and glider rides and
rentals are certainly an excellent avenue for consumers to spend their
money! Furthermore, once launched the glider is a zero-emissions
vehicle - and we are all conscious of environmental impacts and the
cost of energy/fuel these days; so supporting glider operations is
truly an important issue. It is also a wonderful subject for future
government study. Can you imagine how much fuel we could save if we
could develop a glider-based transportation network? To heck with
those noisy and fuel-burning VLJs, why not launch small 3 - 8 person
gliders to 30,000' and then glide to destinations up to 170 miles away
(hey, 200 miles if the towplane climbs at an angle away from the
airport)? That only requires a 30:1 glide-ratio, which is quite
doable with today's technology! All we need is some money from the
government...

--Noel
(who has now used his XCSoar PDA simulator to "fly" a couple of TATs
and understands them much better)