Glide ratio with full brakes and side slip

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.

At 11:30 30 April 2016, 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
sli=
ps 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
so=
unds.

Wow! That is scary!!!

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.

Le mardi 3 mai 2016 06:30:09 UTC+2, George Haeh a écrit*:
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.

As others said before - try that with a DuoDiscus, and tell us what the insurance said.

At 09:31 03 May 2016, Tango Whisky wrote:
Le mardi 3 mai 2016 06:30:09 UTC+2, George Haeh a =E9crit=A0:
Drag increases with the square of the=20
airspeed; so increasing your airspeed=20
from 55 to 75 increases drag by 86%.
=20
With full brakes you can point reasonably=20
modern gliders at the threshold and come=20
down at a constant airspeed. Once you=20
level off the airspeed comes off rapidly=20
with full brake. Ground effect and weight=20
come into play, but even in a G103A it=20
doesn't take that much more runway than=20
a 2-22. Note that I stick to sideslipping in=20
the 2-22.
=20
It can be hard on the guy in the back seat=20
hoping that the guy in the front seat will=20
round out before smacking the nose.=20
=20
And if you round out too high and close=20
the brakes, you will be getting up close=20
and personal with the fence at the other=20
end.

As others said before - try that with a DuoDiscus, and tell us what the
ins=
urance said.



As a duo owner I can tell you it's not the LD that gets you it's the energy
that
you are carrying.
In the first generation if you lowered the nose enough to see where you
were
going the speed builds up,if you kept the speed under control you couldn't

see the field,however if you side slip you can see and control it all.
I have the later xlt and when the flaps deploy everything steadies up and
it is
great.If the engine is out the drag is off the scale.
But still the energy in the ground run is the big danger.

maanantai 2. toukokuuta 2016 15.49.11 UTC+3 Jim Kellett kirjoitti:

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.

Well, not all gliders are the same. I've heard the sentence "I teach this useless thing only because it is required in XXX" too many times. It is required because it is probably very important thing in *some gliders*, not all of them.

I've landed out old Duo couple of times and newer X model (with tiny flaps) too. Every single landing had to be done with full sideslip on final, and required field length was scary compared to light single seaters. I would not sign off anyone to fly Duo without excellent sideslipping technique. Good method is to tell student to fly the whole approach without airbrakes until at treetop height.

On Wednesday, May 4, 2016 at 8:54:50 AM UTC-4, krasw wrote:
maanantai 2. toukokuuta 2016 15.49.11 UTC+3 Jim Kellett kirjoitti:

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.

Well, not all gliders are the same. I've heard the sentence "I teach this useless thing only because it is required in XXX" too many times. It is required because it is probably very important thing in *some gliders*, not all of them.

I've landed out old Duo couple of times and newer X model (with tiny flaps) too. Every single landing had to be done with full sideslip on final, and required field length was scary compared to light single seaters. I would not sign off anyone to fly Duo without excellent sideslipping technique. Good method is to tell student to fly the whole approach without airbrakes until at treetop height.

The method described to students above leaves the pilot with no options if sink or wind change occurs. It is outright dangerous and should not be taught.
It teaches a habitual low sight picture that is certainly not what students should be learning. They need to learn to make steep approaches with optimum energy management.
UH

keskiviikko 4. toukokuuta 2016 17.08.28 UTC+3 kirjoitti:

The method described to students above leaves the pilot with no options if sink or wind change occurs. It is outright dangerous and should not be taught.
It teaches a habitual low sight picture that is certainly not what students should be learning. They need to learn to make steep approaches with optimum energy management.
UH

Glideslope can be managed by increasing sideslip angle, the altitude and approach slope are completely normal. And the options are plenty, they are sitting at the rear seat. I guess you are thinking about making approach very low for avoiding to use sideslip, which is not at all what I meant. The goal is to teach student to use sideslip completely naturally during approach, should they ever need it. If you have other ways to achieve that, that's just fine.

On Tuesday, May 3, 2016 at 12:30:09 AM UTC-4, George Haeh wrote:

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.

I've a friend who does this in a PW-6 from 1000 AGL on short final and have been in the back seat several times. I've done many steep finals at 70-80 knots due to turbulence, so I've given it some thought.

My understanding is that the flare expends the energy used to generate the lift that arrests the vertical speed, and that expenditure of energy reduces the horizontal speed in the flare. Do I have that right?