to dolphin or not to dolphin ?

[Crakob]

Hi guys,
are there any recommendations regarding "dolphin style"

some pull up very hard (and dive hard) others keep it soft some speed right through the lift.

does the lost of speed(time) count for the meters gained ?

i wonder what might be the most effective way ?

christian

[Sprunga]

I'm interested in what the best way is as well!

I generally slow down through lift but keep a bit of speed on depending on how strong it is. I have always thought that any height gained by pulling hard into the lift will be lost again when you are regaining your speed. This is because you are diving to regain speed plus you are in sink. I normally start increasing speed when I think the lift is about to run out so I'm getting close to the right speed for the following sink.

Not sure about a constant speed. I remember someone telling me that Ingo Renner used to fly at the one speed regardless. Not sure it that's true or not?

Interesting to see what the some of the pro's think!

[janjansen]

Not pretending to be a pro, but IMO, f you (can) do it right, you will gain. The sink around the thermal should be less than the climb in the thermal, because the sink is spread over a larger area. In condor I find this isnt always true though.

I think the key factor here is how wide the thermal is. In a narrow thermal, you probably lose more than you gain, because you wont time it perfectly, you might miss the center, you will fly slow through the sink after the thermal and pulling up and pushing down increases drag.

in a wide thermal, I find it does work. But you should try to have regained airspeed before you exit the thermal, otherwise you again find yourself flying 100KmH in heavy sink as you exit.

BTW, you might be able test this by enabling thermal helpers, recording your flight and using ghosts. Have one flight miss the thermal and the other pull up and a third fly straight through the thermal and see if it helps. You will end up with different distances and altitudes, but using the polar you should be able to calculate which of the flights did best. I think.

[janjansen]

Ok, I had to try this myself. I raced against my own ghost. To give the pull up theory the best chances, I set strong and very wide thermals, no variation, high activity and I enabled thermal helpers. I picked an LS8 to ensure incorrect flap settings played no role.

First flight, I flew ~200KmH (McCready 3) through the thermals, without pulling up. I flew through 5 or 6 thermals. Then in the final one, I pulled up and started climbing in a thermal that was around 3m/s. Saved that as a ghost file.

I flew the exact same task again, this time pulling up in each of the same thermals. As expected, I arrived a little later and little higher than my ghost. But who won? I recorded it, showing the ghost wich flew at constant speed, so you be the judge. I would call it a tie:



Maybe a longer task will be more conclusive, and I certainly didnt fly perfectly, pulling up more or less aggressively may change the results a little bit, but I think the takeway here is that there is surprisingly little to be gained. Even with thermal helpers on.

Flying dolphin should help you to stay higher for longer, giving you sightly better odds to find that really good thermal or reaching a point you might otherwise not be able to reach, but the downside is that if you dont hit each and every pull up, and especially if you dont set your flaps perfectly with each pull up, odds are you will lose more than you gain.

Color me surprised, I didnt expect this.

[3P]

If the thermals are really strong and very wide, you can do whole task in dolphins
Reminds me one sweet task back in 2012 on US Nightly Soaring server - Condor v1 with Nimbus4.
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IGC: https://skylines.aero/flights/1839
Forum topic: http://gliderracing.com/forum/Default.a ... sts&t=1258

[janjansen]

If the thermals are really strong and very wide, you can do whole task in dolphins

Which doesnt mean you will do it faster. My short test suggests you probably wouldnt, at least in condor and with a std plane. Things may be different with an open class.

[3P]

Which doesnt mean you will do it faster. My short test suggests you probably wouldnt, at least in condor and with a std plane. Things may be different with an open class.

Yes, I was extremly slow in that race
http://gliderracing.com/pub/dayresults.aspx?c=10&t=1247

[losnively]

I think the other key thing to consider, is that it does matter what sailplane you're using. As Erik mentioned, dolphining in a big ship is more effective than in the smaller ships. I find almost no value to use dolphin flight in club or standard class. In open, at least with the Nimbus, you can make up lots of time. (And, I think this is true in both Condor and RL.)

(Oh, and don't believe anything Erik says about flying slow - I don't think he knows the meaning <smile>.)