Schempp-Hirth Discus B VH-XOT User manual

Darling Downs Soaring Club
Discus B VH-XOT
Serial Number 295
Pilot Handling Guide and Conversion Document
Schempp-Hirth
Rev 0 19 July 2022
These notes are a conversion guide only and not a substitute for the Manufacturer’s Flight
Manual.
This Photo
by Unknown

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Contents
Pilot responsibilities................................................................................................................................3
General notes on conversions ................................................................................................................3
Basic Overview........................................................................................................................................3
The requirements to fly the Discus.........................................................................................................3
External Features ....................................................................................................................................3
Limitations ..............................................................................................................................................4
Cockpit Features .....................................................................................................................................4
Daily Inspection notes.............................................................................................................................5
Glider Accessories and Storage...............................................................................................................5
Flight Characteristics...............................................................................................................................6
Controls:..............................................................................................................................................6
Take-off and Aerotow: .......................................................................................................................6
Thermalling: ........................................................................................................................................6
Cruising: ..............................................................................................................................................6
Stalling:................................................................................................................................................6
Spinning: .............................................................................................................................................6
Water Ballast:......................................................................................................................................6
Circuit and Landing: ............................................................................................................................7
Instrumentation......................................................................................................................................8
Batteries..............................................................................................................................................8
OpenVario ...........................................................................................................................................8
B800 Borgelt........................................................................................................................................9
Flarm ...................................................................................................................................................9
Dittolog ...............................................................................................................................................9
Undercarriage Warning Buzzer.........................................................................................................10
Becker AR302 Radio..........................................................................................................................10
Voltage Display..................................................................................................................................10
Shutting down the Instruments........................................................................................................10
End of the Day.......................................................................................................................................10
Rigging and De-Rigging .........................................................................................................................10
Rigging (Requires 3 people) ..............................................................................................................10
Derigging the glider and putting it in the Trailer ..............................................................................12

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Pilot responsibilities
Clean, Care and maintain the glider, especially after its use ($85k assets!)
Understand how to DI this glider
Understand how to operate the glider (including limitations)
Understand how to Rig / De-Rig the glider
Be familiar with the Discus trailer and its use.
General notes on conversions
The converting pilot must read this document (and referenced documents within), the flight manual.
When you go to do your conversion, an instructor will give you a quiz on the important aspects of
converting to the glider.
1. Your conversion to a new type must be authorized by an instructor who is familiar with the
aircraft type.
2. They should outline the important features of the aircraft.
3. You should not do your first conversion in crosswind or gusty conditions.
4. Spend some time getting comfortable with the cockpit layout.
5. Get someone to lift the tail (while wings level) to show the take-off nose attitude.
6. Note the (minimum) landing nose attitudes with the tail on the ground (while wings level)
For the Discus, you need to purchase your own SD/s card and USB Stick with pre-loaded files.
Purchase these from the DDSC Bar -see Instrumentation Section for more info.
Basic Overview
The Discus is a 15m unflapped sailplane constructed of fibreglass manufactured by Schempp-Hirth
(Germany). This aircraft is the ‘perfect’ cross country glider, very easy to fly glider with very good
performance. The aircraft has retractable undercarriage, conventional airbrakes, water ballast tanks
in the wings and fin. The Discus can be flown with a very light wing loading or a very heavy one. Its
wing loading range is wider than almost any other glider.
The Discus and the Duo Discus are the highest performance gliders in DDSC glider fleet. Both have
very similar performance.
The requirements to fly the Discus
The requirements to fly the Discus are stated in the current Safety Management System - Section 1 -
Standard Operating Procedures - Flying operations and Training available on the DDSC website
External Features
Airbrakes
conventional double
-
height top surface
Flaps
Not fitted
Wing
span/area
15m
/ 10.5sq m
Undercarriage
Retractable
Tailplane
T
-
tail

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Limitations
Vne
Max permitted speed
135 knots
Vra/Va
Max rough air and max manoeuvring speed
108
knots
Vt
Max aerotow speed
91
knots
Max airbrake operation speed
135 knots
Max All Up Weight (MAUW) with water ballast
525
kg
(reference only)
Min
cockpit weight, including parachute
As placarded
Max cockpit weight, including parachute
110
kg
Cockpit Features
Canopy
One-piece canopy hinging sideways. A single red lever (moved
backward) to unlock canopy.
Care needs to be taken when closing the canopy to ensure the tiltable
instrument panel is in the fully down position, shoulder straps aren’t
left over the canopy rail, etc. Always close the canopy slowly and
carefully. It should close smoothly without resistance. If it does not,
investigate and don’t force it!
As with all gliders, care is needed with an open canopy in windy
conditions. Lifting the tiltable instrument panel will provide some
canopy protection from the wind (but do not leave it like this). Always
close and lock the canopy when leaving the cockpit area or ground
handling glider.
At no stage must the canopy itself or clear view side window be held
to lift or close canopy. Only hold the lever or canopy frame when
opening or closing canopy.
Canopy Jettison
In an emergency, the canopy may need to be jettisoned in flight with
the intent of bailing out with a parachute. To do so the following is
done (IAW the Flight Manual paraphrased here)
1. Open the canopy in the usual manner using the lefthand
canopy locking lever
2. With the canopy open, push the righthand canopy jettison
knob forward
3. Throw off canopy
A jettisoned canopy is likely to damage the tail structure of a glider.
Do not jettison a canopy unless committed to bailing out.
Trim Ba
llast
The bulkhead forward of the rudder pedals provides provision to
carry ballast weights to allow lighter pilots to fly the glider.
Only use the specific XOT ballast weights. 3 available
Each weight is equivalent to increasing the pilot’s weight by 5kg
Instruments
See specific section
Seat Adjustment
Backrest angle can be adjusted by moving knob on right side of
cockpit forward or back either inflight or on the ground

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The seat back pivot point can be adjusted on the ground only. Tilt the
backrest forward retract the right hand pin to relocate
The seatback recline cable can also be repositioned on the lefthand
side to give the right hand adjustment a whole new range of
movement. This can only be adjusted on the ground (and only
needed for the smallest of pilots)
Control Column
Conventional with
all
flight computer (OpenVario) controls, PTT
(radio), cruise/climb (toggle switch on front of grip)
Ventilation
Canopy defog control on top left of panel.
PULL – CLOSED
PUSH - OPEN
Trim
Green
lever left hand side of seatpan. Pull the lever inwards to
release/unlock (same as Duo).
Wheel Brake
Hand grip lever
mounted
on
the control column
Tow Rope Release
Conventional yellow handle
on lower left side
Water Ballast Lever
Black knob on right
side
(adjacent to the red canopy jettison. DO
NOT CONFUSE)
Undercarriage Lever
Black handle on right side
of seat pan
Airbrake Lever
Blue handle on left side
of cockpit
Rudder Pedal
Adjustment
Black knob on
lower
right side of control column
Batter
ies
Battery 1 under tiltable instrument panel. Note this must be used for
the placarded pilot’s weights
Battery 2 behind removable panel behind seatback. Ensure the
locating pins are correctly positioned in each top corner before fixing
Daily Inspection notes
In addition to the daily inspection routine:
Tyre Pressures:
oMain Wheel: 50-64 psi
oTail Wheel: 25 psi
To inflate the tailwheel, its aerodynamic fairing needs to be removed. This is attached via 2 self-tap
screws on each end of the fairing. These need to be just tight enough (otherwise you will crack it)
ALWAYS RETAPE FAIRING (as this provides significant restraining force).
All tyres need a valve extension (best to get your own from SuperCheap Auto )
Glider Accessories and Storage
XOT has tow out gear to enable the pilot to tow the glider to the launch point without the need for
extra help. Care must be taken to ensure that the felt on the inside of the wing walker and tail dolly
is in good order and is clean. Storage of tow out gear when not in use is marked on the wall of the
hangar. Do not leave it on the ground.
XOT also has a canopy cover. The cover must be installed when the glider is not in use and make sure
to attach the straps underneath also. When the glider is being flown store the cover in the baggage

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compartment behind the pilot’s head in the cockpit. Take care to ensure cover is kept clean as any
dirt will scratch the canopy when cover is installed. Wash it if required.
Flight Characteristics
Controls:
All controls are light to the feel and are responsive, especially pitch.
Take-off and Aerotow:
For the average pilot (say 75-95kg) set trim forward so that the control column rests gently on its
forward stop).
On the ground roll, raise tail and balance on main wheel when sufficient airspeed is gained. In
ground-effect XOT will ‘fly’ at less than 40knts so the above balanced-ground run is short.
Note: due to the position of the pitot opening (in the nose, adjacent to the tow hook), an airspeed
of 40kts will be indicated on aerotow. Don’t panic! As soon as the tow rope is released, the
correct ASI will be displayed.
Thermalling:
Recommended thermalling speed is 45 knots (50 knots when low). Unlike the Hornet the glider has
no tendency to drop a wing especially if some top rudder is used.
Cruising:
XOT can be flown up to 80 knots (dry) before the sink rate becomes too excessive. The Discus has a
(claimed) 1:42.2 best glide at about 54 knots (320kg).
Stalling:
The Discus stalls in the conventional manner. Recovery is progressive forward movement of the stick
until flying speed is returned.
Stall speed is 35-42 knots (varies with pilot weight). Stall speed (brakes open) is about 2 knots
LOWER.
Spinning:
The Discus has typical spin characteristics and recovers easily with the standard spin recovery
technique. As with any high-performance glider, a polished spin recovery technique is required to
ensure Vne is not approached on the resulting recovery (dive). The average pilot should not
intentionally spin XOT, but by all means practice incipient spins.
Water Ballast:
Water ballast should only be carried by experience cross country pilots in good weather conditions
(ie predicted climbs >4kts). Carrying water ballast brings with its additional challengers/risks, and
any benefit won’t be realised unless the pilot is achieving >100kph cross country speeds (ie it won’t
help and will probably hinder an 80kph pilot).
Carrying water:
makes the takeoff tricky/risky especially if a wing drop occurs (ground crew need to be
experienced with ballasted gliders also)
any land back for a relight is likely to occur with at least some water ballast remaining
thermalling is harder, especially on days with broken/tight thermals

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the thermalling speed is (5+kts) higher (bigger circle)
the glider rear fuselage gets covered in water (then mud after landing) as some always spills
on the flare (unless the dump valves are closed)
the glider cruises faster (which is why we carry ballast) so decisions need to be made
quicker, and more anticipation is needed to stop for a climb (again think cu vs blue days)
need to ensure the glider is not overloaded and the CofG is within limits
With the above cautions, flying with water ballast on high cu days with long glides between
thermals is a lot of fun.
Carrying 30-90 litres is a sweet spot for the Discus. Anything more than this isn’t recommended.
To carry water, you need some means of accurately measuring the water being loaded. Pilots
need to provide their own as this isn’t supplied by DDSC (talk to other pilots about systems they
use).
The ballast tanks are forward of the CofG (in the D of the wing forward of the spar). Therefore a
tail tank is provided to maintain balance when carrying water ballast. Both systems dump water
simultaneously commanded.
The flight manual provides more details on loading and carrying ballast, by roughly 30 litres in
the wings (15 per side) allows 1 litre to be carried in the tail tank (eg 50 litres still only allow 1
litre in tail, however 60 litres means now 2 litres in tail, etc)
If landing with water ballast :
add at least 5knts to safe speed near the ground
be aware that the ground run will be long
don’t taxi off as the water may run to one wing or the other and a wing drop/ground
loop may occur. A wing drop will probably occur anyway.
It will take 3 minutes to drop the majority of a 90 litre load. Always dump ballast before outlanding
(in fact start dumping when low, as any thermals down low will likely be small anyway)!
Circuit and Landing:
Use an approach speed of 60 knots (no wind) – no water ballast with the standard
corrections for wind.
The aircraft is fitted with an undercarriage warning. If airbrakes are deployed with the
undercarriage up, the system will sound.
The flight manual states 2-point landings required. (In fact a previous version of the FM
even suggested the tailwheel should touch first). All this suggests a good hold-off is required
on landing – DO NOT FLY IT ON (you cannot possibly safely outland flying it on?).
Furthermore the Flight Manual discusses the extra energy that must be absorbed with
different touchdown speeds
Good control authority is maintained for the ground roll
On ground roll, hold tail wheel on the ground by applying full back stick. This will help with
directional control and help to prevent the glider nosing over and scraping the belly.

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Instrumentation
Figure 1- Instrument panel
Batteries
Master switch turns on the battery Up for ON; Down for OFF.
Select either 1, 2 or AUTO. XOT has a BMS (battery management system) such that when
the AUTO state is selected, it will manage the batteries in the glider for the pilot. Therefore
AUTO is the recommended position ensuring the both batteries are discharged evenly
(resulting in better short and long term battery longevity)
OpenVario
The OpenVario IS NOT A TOUCH SCREEN. AVOID TOUCHING THE SCREEN. Clean with water
only (like a canopy)
There is a separate and comprehensive manual about the DDSC OpenVario on the DDSC
website
There are many YouTube videos and other info on the web
ohttps://www.youtube.com/watch?v=qppuKiylH_Y&list=PLPHdOV0Gq_NSyApS-
LwkfvtNwopDW68Lf&index=3
othe controls in the video are slightly different to ours. We use the superior control
column system but the functionality is transferable
‘X’ Esc
‘M’ Menu
‘Fn’ mouse/curse mode
thumb remote
pushbutton select/ENTER
up/down/left/right arrow keys/mouse

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You need you own SD card (and ‘special’ USB stick) to operate the OpenVario. This stores
your own profile look and feel for OpenVario.
oThis SD card and USB stick is YOURS and shouldn’t be left in the glider. It would be
wise to back up each in case of lose/corruption.
oThe SD card slot (and USB socket) is provided in the lower most part of the tilt up
panel (see photo above) adjacent to the dittokey reader.
oFeel free to format the look of XCSoar to suit your needs including:
Number and type of screens;
Info boxes
Safety heights (default set at 1000’)
etc. (and setting this is outside the scope of this instruction set.)
DO NOT change ‘Devices’ settings in the Menu otherwise the connected
hardware will cease to communicate
The SD card must be inserted in the panel before the Master Switch is Turned ON (and
remain installed for the duration of the OpenVario’s use). Note - The OpenVario will not
work without an SD card. A ‘dead’ screen most likely means a SD card issue (missing,
corrupt, wrong one ).
After the Flarm and/or Borgelt Vario obtains a GPS fix, the Openvario is ready for use.
The OpenVario power is provided by a unique circuit breaker and switch (labelled computer)
B800 Borgelt
See the Borgelt Manual on the DDSC website
The Vario power is provided by a unique circuit breaker and switch (labelled vario)
The cruise/climb switch is on the front of the column (toggle):
oNote the cruise/climb function will not operate (defaults to climb mode) if the
OpenVario is unserviceable/OFF.
oThe OpenVario will message the mode (cruise or climb)
Flarm
LED Flarm display on upper most part of the panel.
Can also be viewed in detail on the OpenVario by changing screens (‘arrow’ left or right until
the desired screen is reached
Keeping the data.fln file up-to-date in OpenVario will display the Flarmnet database (aircraft
IDs). One is provided by default
The Flarm power is provided by a shared circuit breaker and no switch (labelled
flarm/dittolog). This can only be turned off with the master switch
Dittolog
Each pilot is issued with a unique dittokey. This IDs you as the Pilot.
Insert your key in the lower most part of the tilt up panel (same as every other DDSC glider)
The Dittolog power is provided by a shared circuit breaker and no switch (labelled
flarm/dittolog). This can only be turned off with the master switch.


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Undercarriage Warning Buzzer
A normally closed micro switch on the undercarriage down position, another on the airbrake
locked position is in series with a piezo buzzer
If the airbrakes are unlocked while the undercarriage isn’t locked down, the buzzer will
sound.
The undercarriage warning buzzer power is provided by a shared circuit breaker and no
switch (labelled flarm/dittolog). This can only be turned off with the master switch.
Becker AR302 Radio
See the Becker Manual on the DDSC website
Voltage Display
this device has a momentary pushbutton to activate. It is only ON (after a short delay) while
the button is being held in.
the battery in use (as determined by the BMS) voltage is displayed
this instrument will be updated to perform more functions in the future (stay turned …)
Shutting down the Instruments
Turn the radio OFF
Turn the OpenVario OFF by
MENU
Scroll to last menu item QUIT
Enter, accept YES to shut down, scroll down to POWER OFF, ok, scroll to YES
Turnoff unique switch
Switch off the Borgelt Vario at unique switch
Switch Master down to OFF.
o(Dittolog and Flarm shut off with the master)
End of the Day
Clean the canopy, wings and fuselage.
airbrakes unlocked.
side window (clearview) closed
canopy cover ON
Batteries on charge
Maintenance release completed
If stored with one wing down place some protective carpet and a wing weight on the
lowered wingtip and remove or choke the tail dolly to prevent the glider shifting.
Notify airworthiness officer ([e-mail]) of any defects, problems, or issues
(better still own them and follow through the rectification yourself).
Rigging and De-Rigging
Rigging (Requires 3 people)
1. Orient the front of the trailer into any significant wind and on level firm ground
2. Apply the trailer handbrake on the tow coupling (ensure it is released again before driving
away!!!)