Glide ratio with full brakes and side slip

On Saturday, April 30, 2016 at 4:30:08 AM UTC-7, Jim Kellett wrote:
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.

That's interesting... My ASH-26E is limited to 76 knots with full flaps, so if I find myself a little high a slip brings it down like a falling rock!

-5Z

I fly a 2-22 and a 1-26, I dint need spoilers or a slip to come down like a tock.
Dan

Rock lol

On Saturday, April 30, 2016 at 1:27:33 PM UTC-4, wrote:

That's interesting... My ASH-26E is limited to 76 knots with full flaps, so if I find myself a little high a slip brings it down like a falling rock!

-5Z

Hmmm . . . my ASW-20C has a Vne or 65 kts with landing flaps, but I can get higher descent rates in the landing flap position by increasing airspeed than I can get with a slip! Yes, that IS interesting.

Jim are you hard slipping, meaning using all of your available rudder? Lots of guys don't realky rack it in there and consequently are not getting much drag effect from the fuselage. I had the oportunity to fly an early 20 and while not earth shattering, she would come down pretty good with a hard slip.
Dan

Frankly, a "20" (especially an "A") with landing flaps & full airbrakes comes down fast.
If you "need" a slip, you are either waiting too long to pick a field or need to pick better fields.

The slip likely does not add much drag, more is likely lost from spanwise flow on the wing.

I have several hundred hours in 20 A & C models with too many safe off airport landings.

On Saturday, 30 April 2016 14:30:08 UTC+3, Jim Kellett wrote:

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.

This is the EXACT recipe how to destroy DuoDiscus while landing out. It is so exactly opposite to what you should do that it is almost scary. Probably works on 2-33 or whatever only-slightly-glider-shaped-object you teach on, though.

Le lundi 2 mai 2016 09:54:46 UTC+2, krasw a écrit*:
On Saturday, 30 April 2016 14:30:08 UTC+3, Jim Kellett wrote:

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.

This is the EXACT recipe how to destroy DuoDiscus while landing out. It is so exactly opposite to what you should do that it is almost scary. Probably works on 2-33 or whatever only-slightly-glider-shaped-object you teach on, though.

I totally agree. Side slip with a DuoDiscus works perfectly, and it does increase sink significantly.

You will always increase sink by increasing airspeed with full airbrakes - that will help you if you have a long apraoch without obstacles to bleed of the speed near the ground.

Ij you are landing into a 7-800 ft field over a line of trees, you can do that on a Duo by slipping, but increasing speed will result in a total loss claim.

On Monday, May 2, 2016 at 3:54:46 AM UTC-4, krasw wrote:

This is the EXACT recipe how to destroy DuoDiscus while landing out. It is so exactly opposite to what you should do that it is almost scary. Probably works on 2-33 or whatever only-slightly-glider-shaped-object you teach on, though.

snip

Interesting. I've not flown the Duo very much, and never when I really needed a steep approach, so I can't contribute to any discussion of the peculiarities of that ship. On the other hand, I teach only in G-103s and K-21s, having given up teaching in Schweizer iron entirely about ten years ago. (For sure, a forward slip in a 2-33 is seriously effective at losing altitude, so no argument there!) And, yes, I wss surprised to learn some years back from a colleague who'd been flying in Europe about their practices of full spoiler/increased speed approaches - my first reaction was that it would get really busy in the cockpit at the roundout and touchdown to transition to a slow speed touchdown, but when I tried it, it turned out to be surprisingly easy and really effective.

Drag increases with the square of the
airspeed; so increasing your airspeed
from 55 to 75 increases drag by 86%.

With full brakes you can point reasonably
modern gliders at the threshold and come
down at a constant airspeed. Once you
level off the airspeed comes off rapidly
with full brake. Ground effect and weight
come into play, but even in a G103A it
doesn't take that much more runway than
a 2-22. Note that I stick to sideslipping in
the 2-22.

It can be hard on the guy in the back seat
hoping that the guy in the front seat will
round out before smacking the nose.

And if you round out too high and close
the brakes, you will be getting up close
and personal with the fence at the other
end.