Glide ratio with full brakes and side slip

I was wondering if anyone had an idea of what sort of glide ratio you get with full brakes and slide slip? An instructor used this to correct a very high approach but I was curious what the side slip adds to the descent rate.

I think the average glider goes down to 1:5 when opening airbrakes.

To be certified has the ratio with full airbrakes to be less than 1:7.

I think some also depends on the glider, some don't come down much faster in a slip compared to others. Glass ship won't add much drag slipping compared to a 2-33 in a slip.

Le vendredi 29 avril 2016 14:47:09 UTC+2, Charlie M. (UH & 002 owner/pilot) a écrit*:
I think some also depends on the glider, some don't come down much faster in a slip compared to others. Glass ship won't add much drag slipping compared to a 2-33 in a slip.

If you're slipping a ASK21 with full airbrakes, you are going down with an L/D of 3 or worse. In most glass two-seaters, slipping will increase the drag significantly.

My Pilatus B4 shows almost no effect for slipping, but comes down like a stuka with airbrakes.

On Friday, April 29, 2016 at 11:20:42 PM UTC+12, Per Carlin wrote:
To be certified has the ratio with full airbrakes to be less than 1:7.

At normal approach speed.

Many gliders will do 1:2 or even 1:1 at max airbrake speed (and some few 1:0). However it will then take 500 meters to slow down, so you're better off using a slip at reasonable speed unless the steep dive with brakes will bring you down to a normal approach angle well before the threshold.

When I was doing my cross-country rating in a Std Libelle it was at an away airstrip with a 10 feet high windbreak hedge at the start of the field. After a local soaring flight and standard landing the instructors said "Good. Now go and do another, but this time turn final at the same place but at 1000 ft instead of 300 ft and see if you can get it down". I threw in a full top rudder slip during the turn to final and held it in until about 100m before the fence. And landed shorter then the previous approach.

The Janus also slips scarily well, the Twin Astir not so much, and the DG1000 somewhere in between.

On Friday, April 29, 2016 at 10:26:11 AM UTC-5, Tango Whisky wrote:
Le vendredi 29 avril 2016 14:47:09 UTC+2, Charlie M. (UH & 002 owner/pilot) a écrit*:
I think some also depends on the glider, some don't come down much faster in a slip compared to others. Glass ship won't add much drag slipping compared to a 2-33 in a slip.

If you're slipping a ASK21 with full airbrakes, you are going down with an L/D of 3 or worse. In most glass two-seaters, slipping will increase the drag significantly.

Not sure about that. One demo I've done with students is to fly the final at 6-700' until the runway disappears under the nose. Full brakes and nose on the numbers. Gets some speed going but gets down by 1500.'

By comparison my ASW20 with the deep flaps comes down at 4:1 with the boards out and flaps at 60 degrees. According to the book anyway. I feel like that A model 20 can come down steeper than the 21...

Jordan Pollock

Many gliders will do 1:2 or even 1:1 at max airbrake speed (and some few 1:0). However it will then take 500 meters to slow down, so you're better off using a slip at reasonable speed unless the steep dive with brakes will bring you down to a normal approach angle well before the threshold.


1:0) ---- Emoticon of the student in the front seat the first time you demonstrate a slip at max airbrake speed to landing.

Learn to enjoy slips...it will save your bacon one day.

On Friday, April 29, 2016 at 4:40:57 AM UTC-4, wrote:
I was wondering if anyone had an idea of what sort of glide ratio you get with full brakes and slide slip? An instructor used this to correct a very high approach but I was curious what the side slip adds to the descent rate.

snip

In a modern glider, the side slip is GREAT for crosswind landings, but the forward slip is darn near useless for losing altitude. I teach forward slips to students only because it's in the PTS, but I teach full spoilers and increased speed to get a steep approach. That works like a charm, produces a glide ratio WAY lower than 1:7, and is a lot easier to manage than it sounds.