Guidelines or formulas for how much water to dump in narrow or weakthermal racing?

On Friday, May 15, 2020 at 9:26:29 PM UTC-4, Charles Ethridge wrote:
...and so it begins :-)

The important bit, of course, is to learn how to make the glider go, without water.

T8

Ben:
The best advice I ever got on the subject was, "If you are thinking about dumping the water, DUMP IT!" And that has remained pretty good advice.

The question you have to ask yourself is "why am I thinking about dumping water?" Is it because the last few thermals were weaker? (Dump it). Or, "I am perilously low and I need to float to a save?" (Dump it) Or, "The guys without water are seriously out climbing me and running away" (you guessed it - start dumping).

I think the only time to hold on to the water (when doubts emerge about its helpfulness) is when you are reasonably certain that you will get back to better conditions. This may be because you have started early in the morning before it cooks up or when you have drifted down to the weak area of the height band and can climb back up to the strong lift. But it's not a science - it's an educated guess about the future.

ROY

I understand...BUT...the leading pilots in Condor simulator racing are all, as best I can tell, holding onto their water as long as possible, i.e. they aren't leaning toward the conservative side. This is probably because it is virtual racing, and no one is going to break a real glider (or their real bodies) if they make a water mistake. If I dump water and they don't, they invariably beat me in the cruise segments and especially in final glide..

That's why I was looking for rules of thumb and formulas when racing, as opposed to cross-country.

Ben

On Saturday, May 16, 2020 at 9:09:25 AM UTC-7, Charles Ethridge wrote:
I understand...BUT...the leading pilots in Condor simulator racing are all, as best I can tell, holding onto their water as long as possible, i.e. they aren't leaning toward the conservative side. This is probably because it is virtual racing, and no one is going to break a real glider (or their real bodies) if they make a water mistake. If I dump water and they don't, they invariably beat me in the cruise segments and especially in final glide.

That's why I was looking for rules of thumb and formulas when racing, as opposed to cross-country.

Ben

While Condor is an Excellent tool, many people, fly different on Condor than they would or could in real life!

On Sat, 16 May 2020 09:09:22 -0700 (PDT), Charles Ethridge
wrote:

I understand...BUT...the leading pilots in Condor simulator racing are all, as best I can tell, holding onto their water as long as possible, i.e. they aren't leaning toward the conservative side. This is probably because it is virtual racing, and no one is going to break a real glider (or their real bodies) if they make a water mistake. If I dump water and they don't, they invariably beat me in the cruise segments and especially in final glide.

That's why I was looking for rules of thumb and formulas when racing, as opposed to cross-country.

Ben


Condor is great, but its thermal model isn't correct at low altitudes
(thermals don't get a lot weaker or tighter close to the ground),
therefore there's hardly any penalty if you get very low.

I once got a 6 kts thermal after (!) an outlanding when I bounced back
into the air... and completed my 150 miles task.


Cheers
Andreas

On Friday, May 15, 2020 at 1:18:47 PM UTC-4, Charles Ethridge wrote:
Hi, all.

When racing a typical 1-2 hour flatland race in, say, a Diana2 or Ventus3-15 (15 meter ships with water ballast and flaps), are there any guidelines or formulas for how much water to dump, particularly when thermals are weak or narrow?

Here are the parameters I'm thinking would apply (but I'm no expert yet- thus the question):

1. Average thermal strength
2. Average thermal width
3. Average distance between good thermals
4. Height band for the day

I was hoping to find something on this subject in a glider racing book or the Diana2 flight manual, but no luck so far finding either googling.

Ben Ethridge

If your chronic leecher is underneath you, dump.

As long as you are happy with your climb rate then keep the water. The advantage in the cruise of flying heavy requires no skill or effort but achieving the advantage of lower wing loading in the climb does and it is easy to throw it away through lack of technique or lapse of concentration. As soon as you are unhappy with your climb rate, and don't expect better conditions ahead, then dump it bit by bit until you are. The happiness factor includes things other than theory or algorithm such as comparison with other gliders (if any), conditions ahead, current altitude, terrain below, pilot risk aversion level etc. Stuff that may not seem so important in simulation as in real life.

It build character to climb heavy and then decide to dump just as you head out in cruse ;-)

Here is a paper about flying with water, it is for lower performance gliders but the concepts remain the same.

https://keepitsoaring.com/wp-content...er_ballast.pdf

Other interesting articles by the same author
https://keepitsoaring.com/the-speight-papers/

On Sunday, May 17, 2020 at 11:10:25 AM UTC-4, Jax wrote:
Here is a paper about flying with water, it is for lower performance gliders but the concepts remain the same.

https://keepitsoaring.com/wp-content...er_ballast.pdf


Wow! Excellent article! Adds a lot of "why" to the "what". I need to re-read it a few times to fully absorb. I will read his other articles you link as well.

Thanks!