How to fly fast and win online races

[Aquila]

Of course. No one is arguing you have to religiously chase MC speed, much of this thread is basically about that, but MC provides a theoretical baseline to start from.

Are there no flaws or assumptions or simplifications in your "theory"?

I fly with historical data, using the gliders performance so don't need to consider the polars and the simplifications are the beauty of the method.....so no.

Someone did the math above and it looks pretty good to me.

[arneh]

OK, here is another topic; what is your secret to achieve good race starts? I wasnt very good at it in C2, but eventually got used to (nearly) fluttering over the start line.

As mentioned by Wiek, I use the LX final glide calculator for starts.
A tip for hitting the timing for regatta starts. If the start speed limitation is 170, then you will do 6km in just over two minutes (if the limit is 250 then you will do 8 km in 2 minutes). So I aim to be 6 km from the start line 2 minutes before start opening, and holding a consistent 170kph all the way. Assuming I have enough altitude to do that. Then you just have to keep a constant speed and adjust altitude with airbrake to make perfect start a few seconds after opening

Having this long 2 minute run in makes it easier to set everything up, and you don't have to make huge late second adjustments to hit the numbers.

And to make sure the LX is calculating distance to the line, and not the back of the sector, go into edit task -> zone for start and change it into a line, instead of sector.

[timbaeyens]

Xcsoar Infobox "Next Altitude Arrival" (WP AltA) does that as well, I think?

[janjansen]

Id have to test, I think its like condor PDA, DDH to ground level (and using current MC). If you are more organized than me perhaps you can do the math before hand, but then Id rather use the PDA as xcsoar is far off to the side.

As for LX, I gave it an honest try, but my brain just isnt compatible with the way it works, and not being able to scale it on my secondary monitor makes me unwilling to rewire my brain . If a less than ideal start is the price for that, so be it.

[timbaeyens]

Xcsoar Infobox "Next Altitude Arrival" (WP AltA) does that as well, I think?

It works towards the start pole.
But it is maybe being worked on: https://github.com/XCSoar/XCSoar/issues/1507

[Bre901]

CoMoMap also points to the start pole, but I think I will change that to the nearest point on the start line (already available for finish).

I might also add the display of the transition speed according to MC, which would allow to set the glide towards the line by setting MC so that it is the max start speed

As I have to release a new version soon (TP sector on the map border bug fix + wall clock), I might take a look at that also

[ryanwoodie]

How did you calculate the 2.7% difference Ryan?

Oops, now my math is wonky I glanced at the wrong piece of the equation when typing. It is a 3.4% difference

(Or, if you meant how to calculate the the speed: 117km / (1 + (.99m/s / 2m/s) = 117km/1.495hrs = 78.26km/h )

LIke I said, there can be many good reasons to deviate from MC, probably all of which are already mentioned in this thread, but you do that deliberately for that reason when its appropriate, by an amount that's appropriate, not because one number is half another number that in some circumstances happens to be close to MC.

Agreed. I just wanted to highlight the big gain in reach (ie. ability to avoid weak climbs, get stuck, etc) that a small reduction in theoretical average speed provides.

[Bre901]

How did you calculate the 2.7% difference Ryan?

Oops, now my math is wonky I glanced at the wrong piece of the equation when typing. It is a 3.4% difference

(Or, if you meant how to calculate the the speed: 117km / (1 + (.99m/s / 2m/s) = 117km/1.495hrs = 78.26km/h )

I beg to differ, the difference is indeed 2.8% if you use your formula
The cruise speed of the empty StdCirrus @MC=1m/s is 119km/h, it sinks @1.0265m/s (=119/32.2/3.6), hence the cruise speed is 78,64 km/h

The figures you have used are for MC=0.9m/s

I have edited my above post to add percentages
https://www.condorsoaring.com/forums/vi ... 70#p190170

Values in my spreadsheet are marginally different as I make some interpolations between data taken from the flight planner

[ryanwoodie]

I beg to differ, the difference is indeed 2.8% if you use your formula
The cruise speed of the empty StdCirrus @MC=1m/s is 119km/h, it sinks @1.0265m/s (=119/32.2/3.6), hence the cruise speed is 78,64 km/h

The figures you have used are for MC=0.9m/s

Yes, I was merely referencing the figures in janjansen's polar screenshots which were 0.9m/s and 2.0m/s. Just a happy coincidence that my typo happened to match the % difference between 1.0 vs 2.0 MC average XC speeds when both have 2m/s climbs!