Dolphin flying

Steve is correct that we fly slower as we get lower, but that does not mean you should fly slower than your MC setting. In my first posting I stated that the MC should be set to the thermal strength you are willing to stop for. Rather than flying slower than an unrealistic MC setting, turn the MC down to what you are willing to take.

As Uncle Hank said there is no perfect answer that fits all situations, all decisions depend on many other factors including the conditions and terrain ahead.

John Cochrane's article "Just a little faster please" is a must read on the topic:
http://faculty.chicagobooth.edu/john...ring/index.htm

if you download the trace, you can see a remarkably long 100 mile run northward, below 4000 feet, with a -601 L/D for the last 76 miles

MB

when I flew this past summer on a 4-hour and an 8-hour flight with a Very Experience Pilot (who shall remain nameless should I misstate), his technique on long legs (we had some 30 minute straight-ahead legs!) was to slow down in rising air, and initiate a turn. Once the plane caught up with the control inputs, he would decide to march on ahead if the lift was weak, s-turn (to keep the plane pointed generally in the right direction) when the lift was medium, and thermal when it was strong. YMMV. he very rarely thermalled, unless we really needed the altitude. --bob

On Friday, February 12, 2016 at 2:46:48 PM UTC-5, Jonathan St. Cloud wrote:
Was reading an article by Mike Borgelt that when flying through a thermal you will not circle in you should just fly the STF.

I have always slowed in such thermals, sometimes slowing to thermal speed while putting the thermal flaps. I do try to accelerate before I leave the lift. My thought being try to stay in the lift as long as possible while still moving forward, sometimes even s-turning to stay in large thermal but still moving down the course line.

Would appreciate any comments, critique, thoughts...

Gentlemen -

One thing to remember - there is contest flying and there is non-contest flying.

While I understand that the theory is exactly the same, I would expect very different tactics between a Nationals contest flight and an OLC flight.

Especially for an OLC flight where time or speed is not a critical component, I would expect a more conservative strategy would be found to be the norm.

Lou

On Saturday, February 13, 2016 at 2:18:18 PM UTC-5, MNLou wrote:
Gentlemen -

One thing to remember - there is contest flying and there is non-contest flying.

While I understand that the theory is exactly the same, I would expect very different tactics between a Nationals contest flight and an OLC flight.

Especially for an OLC flight where time or speed is not a critical component, I would expect a more conservative strategy would be found to be the norm.

Lou

I fly almost exactly the same whether practicing or racing. It doesn't pay to change my style.
For the best OLC flight you are still trying for the best speed given the time you fly so as to maximize points.
UH

On Saturday, February 13, 2016 at 2:18:18 PM UTC-5, MNLou wrote:
Gentlemen -

One thing to remember - there is contest flying and there is non-contest flying.

While I understand that the theory is exactly the same, I would expect very different tactics between a Nationals contest flight and an OLC flight.

Especially for an OLC flight where time or speed is not a critical component, I would expect a more conservative strategy would be found to be the norm.

Lou

To sorta echo "UH's" comment...... the ONLY time I was allowed to, "Do something stupid that may break the glider..." was:
-Last day of a US Nats or worlds
followed by
-If it works, you win......."

Period.

Otherwise, "Train as you race, race as you train".

I agree that the US frowns upon "team flying" in it's contest, frankly (in disagreement to some on RAS), I think this is a TON more against the US doing well in the "world stage" than what type of tasks we tend to fly here (in the US).
A good team can have a high level of finish IF they help each other.
In the discussion of "leeching", depends on whether you are worried about US rankings or world rankings.

OK Sean F., have at it.

[back to stoking my fire, it's a "wee bit chilly" in north NJ. USA]

On Saturday, February 13, 2016 at 2:18:18 PM UTC-5, MNLou wrote:
Especially for an OLC flight where time or speed is not a critical component,
I would expect a more conservative strategy would be found to be the norm.

Absolutely wrong. OLC is a race, just like contests.
XC, you are always flying against the clock, the end-of-day, as fast as possible.
Otherwise you don't get home before sunset, end-of-lift, etc.
Time and speed is *always* critical.
IIRC explained in Reichmann ;-)

On Saturday, February 13, 2016 at 10:34:32 AM UTC-5, Soartech wrote:
Hint:
http://www.onlinecontest.org/olc-2.0...htId=185517315

See ya, Dave

Dave, What is your point here?

MacCready theory is not always applicable.
Consider:
- What are MacCready theory's assumptions, and when are these not valid?
- Why do good flights often beat expected MC speeds (after accounting
for start-finish altitude differential)?

Hopefully this will be covered in the V3 talk at the convention;
Tilo tells me by analyzing OLC piles of flight logs, the actual
behavior of top pilots shows this, thus better informs how the glider
should be optimized...

Hope this helps,
Best Regards, Dave

Jonathan,

Your approach is a good one and there is not an entirely clear answer. I think it really depends on the glider you're flying and your given situation. There are a couple things at play.

1) Time in lift/sink
2) Dynamic Soaring effect (from the pull-up)
3) Tactical considerations

So for the simple speed-to-fly indicator, it is telling you the optimal mathematical speed to maximize time in rising air. It does NOT assume the drag from a rapid pull-up. It is near to impossible to chase the needle and to do so would be inefficient in its own right. However, maximizing time in lift relative to sink is certainly a good thing and it makes sense to slow down in the good air or thermal. The question is how much. If you are in a relatively big area of lift and you can gradually pull up (1.5-2g max), then following the STF could make sense.)

Now, in some gliders you can pop off the air (dynamic soaring). This particularly works well with light wing-loaded gliders and/or gliders that have low induced drag and airfoils that are not prone to separation. In these gliders, dolphin flying carries a different meaning as you are extracting energy by the very act of pulling against the gust or thermal. The STF is irrelevant in these cases.

Some examples of gliders I had flown-

1) Schweizer 1-26E-

Great dolphining machine! The stiff wings and the very light wing loading let you pop off the gusts really well. The strategy for dolphining, especially into the wind is to slow down to minimum sink, sometimes even to minimum controllable airspeed and milk out the air as much as possible. The goal is to avoid turning at all costs. There is a huge amount of energy gained from dolphining/dynamic soaring off the vertical gusts. On a convective day in the East, it is possible to consistently achieve 25-1 glides by doing this.

2) LS-4

Mediocre dolphining glider. No flaps, so lots of drag on pulls. Much better to smoothly slow down to best glide, possibly to minimum sink if the thermal is quite big.

3) Standard Cirrus-

Awful dolphining machine. Huge airflow separation when changing angle of attack. But really great performance in club class just flying straight and smooth!

4) Duckhawk-

Unbelievably awesome dolphining sailplane. Auto-flaps, so perfect AoA on pull-ups, low induced drag, low separation make it conserve most of the energy on big deviations. Makes a lot of sense to pull hard and often.

(Listen to Bill Thar's speech at convention about Auto-flaps to learn more)

The tactical consideration is relevant in that there are two types of dolphin-flying. There is dolphining to get more altitude, and for greater speed, both which have a different technique. When dolphining for more altitude, I will cruise slower, pull more aggressively and slow down to minimum sink. When dolphining for "speed", I do gentle vertical deviations, less draggy, but to spend a bit more time in the lift compared to sink.

In practice, here are two scenarios-

1) You are going upwind and you have found a thermal street. You are climbing, drifting downwind. The question is when do you leave? You can leave earlier, slowly float up in the street by wafting up, or you can leave later and then blast along cloudbase. Generally I find it more efficient to leave earlier and waft up.

2) You are on final glide low. You need to make up 1000ft. Then dolphin more aggressively and pull out every bit of altitude. Once final glide is made, then speed up and don't deviate vertically as substantially.

Hope these thoughts were of interest.

Best Regards,
Daniel

Hank, Charlie, and Dave -

I should have made myself more clear -

For you "contest monsters" who focus on, fly, and win at the National level, of course you are always racing - even when you are practicing. That's what it takes to get fast. If you fly OLC, you max it out.

My contrast to a contest pilot was a pilot who flies XC but isn't trying to max out speed - just get around the course. Think a 200km triangle on a mid-summer day. Doesn't care too much about speed or how may OLC he/she gets. Just wants to have fun, go someplace, and get home.

I believe that pilot would fly more conservatively to maximize altitude and minimize the risk of landing out. A faster speed that eats up more altitude gains them nothing and potentially costs them big time.

Lou