How gliders fly

Some may find this useful.

http://www.boldmethod.com/blog/artic...glider-flying/

On Thursday, March 19, 2015 at 4:17:56 AM UTC+13, Frank Whiteley wrote:
Some may find this useful.

http://www.boldmethod.com/blog/artic...glider-flying/

Well it's not *horrible*.

For any non-glider pilots who happen to come across this:

- in fact single seaters are more common than two seaters

- airbrakes are nearly universal, flaps on relatively few gliders (20%?)

- ridge lift commonly goes to 2-3 times the height of the ridge, often several thousand feet.

- big span makes slow roll rate, yes, but more an issue for aerobatics (rolls) than for rapid entry or exit from turns, which gliders do more of than most aircraft. Most gliders can do 45 deg turn one way to 45 deg turn the other way in 4 - 6 seconds at normal thermalling speeds (45 - 55 knots), or quite a bit less when flying even 10 knots faster, as you do for safety if you're close to solid ground.

- with modern glider Vne in the 260 - 300 km/h range (140 - 160 knots), gliders are not slower than typical single engine piston planes.

Hmm, where I fly ridge lift rarely goes higher than 1x ridge height.

Ramy

On Wednesday, March 18, 2015 at 11:26:47 AM UTC-7, Bruce Hoult wrote:
On Thursday, March 19, 2015 at 4:17:56 AM UTC+13, Frank Whiteley wrote:
Some may find this useful.

http://www.boldmethod.com/blog/artic...glider-flying/

Well it's not *horrible*.

For any non-glider pilots who happen to come across this:

- in fact single seaters are more common than two seaters

- airbrakes are nearly universal, flaps on relatively few gliders (20%?)

- ridge lift commonly goes to 2-3 times the height of the ridge, often several thousand feet.

- big span makes slow roll rate, yes, but more an issue for aerobatics (rolls) than for rapid entry or exit from turns, which gliders do more of than most aircraft. Most gliders can do 45 deg turn one way to 45 deg turn the other way in 4 - 6 seconds at normal thermalling speeds (45 - 55 knots), or quite a bit less when flying even 10 knots faster, as you do for safety if you're close to solid ground.

- with modern glider Vne in the 260 - 300 km/h range (140 - 160 knots), gliders are not slower than typical single engine piston planes.

Our local "traing ridge" is 1500ft bottom to top. Top at 4300MSL and I've easily reached 3500ft above the ridge 8000MSL and still had a strong climb but had to leave for overhead airspace. I've easily gained more than 3000ft above an 800ft ridge at Jacumba CA from a winch launch.

I've flown in wave off 2500 ft high ridge line (6500MSL) and easily reached 13,500 MSL and had to stop the climb still in 5knt up because of lack of O2 for me and the Pax.
BillT

On Wednesday, March 18, 2015 at 8:25:40 PM UTC-7, Bill T wrote:
Our local "traing ridge" is 1500ft bottom to top. Top at 4300MSL and I've easily reached 3500ft above the ridge 8000MSL and still had a strong climb but had to leave for overhead airspace. I've easily gained more than 3000ft above an 800ft ridge at Jacumba CA from a winch launch.

I've flown in wave off 2500 ft high ridge line (6500MSL) and easily reached 13,500 MSL and had to stop the climb still in 5knt up because of lack of O2 for me and the Pax.
BillT

Of course one can climb very high of a ridge in ridge induced thermals and wave. I often climb to 18,000 feet in wave from a 2500 feet ridge. But in pure ridge lift it is uncommon to climb much more than 1 x time ridge height..

Ramy

On Thursday, March 19, 2015 at 6:17:03 PM UTC+13, Ramy wrote:
Of course one can climb very high of a ridge in ridge induced thermals and wave. I often climb to 18,000 feet in wave from a 2500 feet ridge. But in pure ridge lift it is uncommon to climb much more than 1 x time ridge height.

You're saying you can't get above the top of the ridge?

That may be true with very shallow slopes and light winds, but it's not the case here.

To the south of our field we have ~800 ft high sea cliffs and in 20+ knot onshore winds we can often run along at zero sink at 80 - 100 knots at 2500 ft (the airspace limit in that area). No thermals or wave involved. Lift at ridge top height is often in excess of 1000 fpm.

To the north we have a ridge 5 km inland about 1700 - 1800 ft high which almost always gets us to 3500 ft and sometimes to 5000 ft in pure ridge lift.

On Wed, 18 Mar 2015 23:16:33 -0700, Bruce Hoult wrote:

On Thursday, March 19, 2015 at 6:17:03 PM UTC+13, Ramy wrote:
Of course one can climb very high of a ridge in ridge induced thermals
and wave. I often climb to 18,000 feet in wave from a 2500 feet ridge.
But in pure ridge lift it is uncommon to climb much more than 1 x time
ridge height.

You're saying you can't get above the top of the ridge?

That may be true with very shallow slopes and light winds, but it's not
the case here.

To the south of our field we have ~800 ft high sea cliffs and in 20+
knot onshore winds we can often run along at zero sink at 80 - 100 knots
at 2500 ft (the airspace limit in that area). No thermals or wave
involved. Lift at ridge top height is often in excess of 1000 fpm.

To the north we have a ridge 5 km inland about 1700 - 1800 ft high which
almost always gets us to 3500 ft and sometimes to 5000 ft in pure ridge
lift.

From quite limited ridge experience I have the impression that the shape
of the ridge and the nature of surface upwind of it have a major effect:

- the Bishop at Portmoak is 1100 ft high, fairly steep, backed by a
plateau and fronted by a Loch Leven with a smooth, shallow slope. Even
in fairly light winds its easy enough to get to 3000 ft above the the loch

- by contrast, both Long Mynd and Sutton bank have a similar slope and
flat tops. They are around 700 ft high but with rougher ground/small
hills across a valley upwind and in similar light conditions its hard to
get more than 500 ft above the ridge.

- I've also flown at Paraparaumu, also only in light conditions and, as
Bruce says, it was no great trick to get to at least the ridge height
again above the ridge there. Once again the wind comes across smooth
ground after it laves the sea.

Of course, as a mainly flat-land/thermal pilot, I'm not great at using
ridges, but at least I can say that I've flown all these ridges apart
from Sutton Bank in the same glider or type of glider.


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martin@ | Martin Gregorie
gregorie. | Essex, UK
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