Flaps VS Airbrakes/Spoilers

On 18/08/2011 00:44, Eric Greenwell wrote:

Not only do they look like it, they are, in fact, bent down a bit. I saw
that on my ASW 20 C, and I see it on my ASH 26 E.

But that's not really due to the flaps. The clever Schleicher mixer
design raises the ailerons as the flaps move to landing. ASH-25s show
it best of all.

That's why longer span Schleicher gliders are significantly easier to
manoeuvre on final than some other contemporary designs.

GC

Here is a video example of flaps...(on powered planes)

http://freedom4um.com/cgi-bin/readart.cgi?ArtNum=133255

Scott

On 8/17/2011 2:50 PM, GC wrote:
On 18/08/2011 00:44, Eric Greenwell wrote:

Not only do they look like it, they are, in fact, bent down a bit. I saw
that on my ASW 20 C, and I see it on my ASH 26 E.

But that's not really due to the flaps. The clever Schleicher mixer
design raises the ailerons as the flaps move to landing. ASH-25s show it
best of all.

My inner engineer must quibble with this, though I agree it is a clever
mixer system. On my 26 E, it even puts a little washout (ailerons up
slightly) in the thermalling flap position to improve control at low
circling speeds.

For the landing, it's the difference in control surface deflection that
does it: the high lift coefficient flap section requires a very low
angle of attack to produce the proper lift, so low that the low lift
coefficient aileron section is producing negative lift.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl
- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz

On Aug 18, 7:39*am, Jonathon May wrote:
The duo discus has always been a great glider but it was not easy to
land.The latest version XL has flaps connected to the air brakes,and it has
transformed it's approach control to the point it is just as easy to land
as a K21.When the total mass is750Kg you need to let the designer do the
designing

I'm experienced in the Janus (original model: flying tail, belly hook
only) and in the DG1000 but I've only had one flight in a Duo.

The Guy In Back got a bit preoccupied in the circuit trying to get a
balky radio to work, so I set up a reasonably tight final the same as
I would for a half brake approach in the DG1000 or Janus (with landing
flap).

Oops!! Captain she's not coming down!! It seems that they put pretty
much the same wimpy brakes in the Duo as in the Janus, but without the
benefit of the flaps.

Full brake did end up bringing us down to the threshold (which turned
out to be unnecessary as I was then told to land long) but it did
require everything, not the half I'd planned for.

On 18/08/2011 08:40, Eric Greenwell wrote:
On 8/17/2011 2:50 PM, GC wrote:
On 18/08/2011 00:44, Eric Greenwell wrote:

Not only do they look like it, they are, in fact, bent down a bit. I saw
that on my ASW 20 C, and I see it on my ASH 26 E.

But that's not really due to the flaps. The clever Schleicher mixer
design raises the ailerons as the flaps move to landing. ASH-25s show it
best of all.

My inner engineer must quibble with this, though I agree it is a clever
mixer system. On my 26 E, it even puts a little washout (ailerons up
slightly) in the thermalling flap position to improve control at low
circling speeds.

For the landing, it's the difference in control surface deflection that
does it: the high lift coefficient flap section requires a very low
angle of attack to produce the proper lift, so low that the low lift
coefficient aileron section is producing negative lift.


My inner engineer will pay that.

GC