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Fastest way home?



 
 
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  #1  
Old June 17th 13, 07:32 PM posted to rec.aviation.soaring
JJ Sinclair[_2_]
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Default Fastest way home?

The last day at Montague was spectacular, probably the best soaring day I have ever seen! After flying 7 assigned turn-points in an 8-turn (3hr) MAT, I was 45 miles out with 3500' over MC-3 glide home and the SN-10 said I would be 4 minutes over the 3 hr minimum time. My stats page told me I was doing 70 mph so far after cruising 80 knots all day long.

Question: Is it faster to raise the MC to 4 or 5 and come home at 90'ish (monitoring time and altitude required), probably bringing my time remaining down to zero..............Or should I use my excess altitude to select another turn-point adding 10 more miles to the total distance and continue to cruise at 80 and be overtime about 13 minutes?

I did the latter and got 73.5 mph (236 miles), but I have a sneaking feeling I should have done the former.
JJ
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  #2  
Old June 17th 13, 08:32 PM posted to rec.aviation.soaring
JJ Sinclair[_2_]
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Posts: 359
Default Fastest way home?

On Monday, June 17, 2013 11:32:22 AM UTC-7, JJ Sinclair wrote:
The last day at Montague was spectacular, probably the best soaring day I have ever seen! After flying 7 assigned turn-points in an 8-turn (3hr) MAT, I was 45 miles out with 3500' over MC-3 glide home and the SN-10 said I would be 4 minutes over the 3 hr minimum time. My stats page told me I was doing 70 mph so far after cruising 80 knots all day long.



Question: Is it faster to raise the MC to 4 or 5 and come home at 90'ish (monitoring time and altitude required), probably bringing my time remaining down to zero..............Or should I use my excess altitude to select another turn-point adding 10 more miles to the total distance and continue to cruise at 80 and be overtime about 13 minutes?



I did the latter and got 73.5 mph (236 miles), but I have a sneaking feeling I should have done the former.

JJ


OK, I got the E-6B out and answered my own question:

First option (speed up) 226 miles at 3:00 hrs = 75+ mph

Second option (add 10 miles distance) 236 miles taking 3:13 = 73 mph

So, in this example it is 2 miles per hour faster to just speed up and not add extra miles to the total.
Cheers,
JJ
  #3  
Old June 18th 13, 09:07 AM posted to rec.aviation.soaring
waremark
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Default Fastest way home?

I think there is a simpler way of knowing the answer. If you can go faster without reducing the time remaining below zero then that will be better.
  #4  
Old June 18th 13, 02:36 PM posted to rec.aviation.soaring
JJ Sinclair[_2_]
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Posts: 359
Default Fastest way home?

On Monday, June 17, 2013 11:32:22 AM UTC-7, JJ Sinclair wrote:
The last day at Montague was spectacular, probably the best soaring day I have ever seen! After flying 7 assigned turn-points in an 8-turn (3hr) MAT, I was 45 miles out with 3500' over MC-3 glide home and the SN-10 said I would be 4 minutes over the 3 hr minimum time. My stats page told me I was doing 70 mph so far after cruising 80 knots all day long.



Question: Is it faster to raise the MC to 4 or 5 and come home at 90'ish (monitoring time and altitude required), probably bringing my time remaining down to zero..............Or should I use my excess altitude to select another turn-point adding 10 more miles to the total distance and continue to cruise at 80 and be overtime about 13 minutes?



I did the latter and got 73.5 mph (236 miles), but I have a sneaking feeling I should have done the former.

JJ


In this case you are correct, but lets say my accumulated speed was lower but conditions appear to offer a faster leg if I decided to add another turn-point and by flying over the minimum time I would increase my overall speed. Not sure how to make this decision quickly other than a quick guess-t-estimate.
Cheers,
JJ
  #5  
Old June 18th 13, 08:27 PM posted to rec.aviation.soaring
[email protected]
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Default Fastest way home?

On Tuesday, June 18, 2013 9:36:25 AM UTC-4, JJ Sinclair wrote:
On Monday, June 17, 2013 11:32:22 AM UTC-7, JJ Sinclair wrote:

The last day at Montague was spectacular, probably the best soaring day I have ever seen! After flying 7 assigned turn-points in an 8-turn (3hr) MAT, I was 45 miles out with 3500' over MC-3 glide home and the SN-10 said I would be 4 minutes over the 3 hr minimum time. My stats page told me I was doing 70 mph so far after cruising 80 knots all day long.








Question: Is it faster to raise the MC to 4 or 5 and come home at 90'ish (monitoring time and altitude required), probably bringing my time remaining down to zero..............Or should I use my excess altitude to select another turn-point adding 10 more miles to the total distance and continue to cruise at 80 and be overtime about 13 minutes?








I did the latter and got 73.5 mph (236 miles), but I have a sneaking feeling I should have done the former.




JJ




In this case you are correct, but lets say my accumulated speed was lower but conditions appear to offer a faster leg if I decided to add another turn-point and by flying over the minimum time I would increase my overall speed. Not sure how to make this decision quickly other than a quick guess-t-estimate.

Cheers,

JJ


It's basically the same problem to solve when flying an area task: are you
flying fast enough to make up for diluting the contribution that final glide
makes to your speed? Keep in mind that you're getting a free segment of flight
from your start altitude down to your finish altitude, flown at your final
glide or interthermal speed. The longer the time you spend on course, where
average speed is less than that, the more you dilute that glide.

There are occasions where it makes sense to extend the flight (e.g. you spent a
long time digging out of a hole). More often, it hurts less than you think
to come in a little early. As John Good pointed out to me, don't just slow
up your final glide to use up those couple minutes you'll be early. You
actually get more points by flying faster.

Matt
  #6  
Old June 18th 13, 09:25 PM posted to rec.aviation.soaring
C-FFKQ (42)
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Default Fastest way home?

On Tuesday, 18 June 2013 15:27:15 UTC-4, wrote:
... More often, it hurts less than you think
to come in a little early. As John Good pointed out to me, don't just slow
up your final glide to use up those couple minutes you'll be early. You
actually get more points by flying faster.

Matt


Okay, I'll bite (probably regret it...) How can you get more points by flying faster in this situation? I'll declare up-front that I'm not a racer, so I might be misunderstanding the rules and scoring.

Whether you slow down and hit the finish at exactly the right time (not over), or fly faster and arrive earlier, you're still scored for the same distance and the same time. Definitely, if you slow too much and cross after the minimum, you lose points, so I would think arriving early guarantees you the best score for the distance (but not "more" points, given a finish at minimum time).

Basic equation of distance / (greater of actual time or minimum task time)
  #7  
Old June 18th 13, 09:54 PM posted to rec.aviation.soaring
Steve Leonard[_2_]
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Default Fastest way home?

On Tuesday, June 18, 2013 3:25:24 PM UTC-5, C-FFKQ (42) wrote:
Okay, I'll bite (probably regret it...) How can you get more points by flying faster in this situation? I'll declare up-front that I'm not a racer, so I might be misunderstanding the rules and scoring. Whether you slow down and hit the finish at exactly the right time (not over), or fly faster and arrive earlier, you're still scored for the same distance and the same time. Definitely, if you slow too much and cross after the minimum, you lose points, so I would think arriving early guarantees you the best score for the distance (but not "more" points, given a finish at minimum time). Basic equation of distance / (greater of actual time or minimum task time)

The US rules will score you at some ratio between your actual time on course and the minimum time on course if you are under minimum time, but not more than 15 minutes under minimum time. So, if the minimum task time is 3 hours, the pilot that comes back in, say, 2:54:20 will get a slightly higher speed for the same task distance as the pilot that comes back at 3:00:00. This was done to make it so that you didn't have a tie for everyone who was undertime but hit the same turnpoints. Of course, this was also in the days when if you went to the same turnpoints, you got the exact same distance.. i.e., pre GPS documentation of the flight.

It might pay if you are really early to hang out to be 00:14:59 under time, as opposed to being 00:15:01 under time. Another of those "edges" that a rule defines.

There is another thing that happens in the US rules if you are more than 15 minutes under time. It has to do with potentially reducing the number of points the winner for the day will get if enough of the pilots are more than 15 minutes under time.

Hope that hasn't made your head hurt too much!

Steve

  #8  
Old June 18th 13, 10:25 PM posted to rec.aviation.soaring
C-FFKQ (42)
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Default Fastest way home?

On Tuesday, 18 June 2013 16:54:52 UTC-4, Steve Leonard wrote:
... Hope that hasn't made your head hurt too much!
Steve


Thanks, Steve. That does make sense.
  #9  
Old June 18th 13, 11:51 PM posted to rec.aviation.soaring
Steve Koerner
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Default Fastest way home?

I'm annoyed with myself that I didn't know this.

Can anybody express this adjustment quantitatively for us? Otherwise, I guess I'll have to ploy through the scoring formula all by my lonesome.
  #10  
Old June 19th 13, 02:11 AM posted to rec.aviation.soaring
Tony[_5_]
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Default Fastest way home?

11.6.3.2 For finishers whose TOC is less than MINTIME:
STOC = MINTIME - (MINTIME - TOC) * UTFACTOR
For a Turn-area task:
UTFACTOR = 0.1 + 6 * ((DIST
 




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