Document 6599376

With their ‘DG-200’ now Glaser-Dirks has become the fifth German manufacturer to join the stampede into the 15-metre class. Our picture shows you the DG-200
during a flight over Klippeneck.
Aerial photograph by D. Geistmann.
‘DG-200’ is the unpretentious name for the new flagship model
for the 15-metre class from the Glaser-Dirks company of
Bruschal. The DG-200 provisionally completes the DG-family
which is so far represented successfully in the standard class by
the easy-to-fly club model DG-100-G (with conventional
elevator) as well as the sharper competition version DG-100
(with all-flying tail). In the near future the company expects to
deliver 100 machines of this sample type.
Following the ASW-20, the LS3 / Mini-Nimbus, the Mosquito
and the PIK-20D the DG-200 is the fifth production sample of
the new 15-metre class to enter manufacture. Although the DG200 has been announced fairly promptly, Glaser-Dirks has not
rushed the development nor failed to carry out the necessary
experimentation. Instead this relatively young company has
developed quite ambitious plans and has tried to achieve an
optimum design, consistently exhausting all of the conventional
possibilities.
The goal which Glaser-Dirks set
themselves was to reach the
performance of a 17-metre flapped
glider but with a span of 15 metres.
As a reasonably ambitious but
achievable goal it was decided to
target the Glassflugel Kestrel, an
open-class machine no longer in
production.
So Dipl.-Ing. Wilhelm Dirks the
technical designer, is happy with
the comparison of the DG-200 with
the17-metre
Kestrel
in
that
following Dirk’s own opinion and
different comparison flights it is
easy to see that the DG-200 has a
distinct performance advantage
over the Kestrel in high-speed
flight over 200 kilometres per hour.
The best L/D indicated by GlaserDirks of 42.5 is identical with that
of the Kestrel. All three aircraft
used for these comparisons, the
Kestrel, DG-100 and DG-200,
were flown with approximately 90
kg additional load but without
water-ballast. The DG-200 is not
yet approved however the machine,
whose first flight took place on
22nd April 1977, has been at least
under consideration for the FAI 15metre class since the German
championships at Paderborn. A
point already for discussion is that
the glider left a substantially better
impression
in
the
German
championship than its final placing
in the results table would perhaps
imply. With hindsight it may have
been the wrong decision for
Wilhelm Dirks to fly the DG-200 at
Paderborn, because with the high
standard
of
the
German
championships it is not sufficient to
be an excellent pilot; one must be
able to ‘walk on water’, a tactician
par excellence, if one wants to be
up with the leaders. And for this,
Dirks was simply not in the
championship league. But probably
no-one knows that better than Dirks
himself. On the other hand it says
much for him that he did not shy
away from competing at Paderborn,
and as a technical designer in this
competition he will possibly have
been able to seek out weaknesses in
the design so that these do not
continue into production. It may be
that Dirks had to pay an expensive
price for this in Paderborn, but
Paderborn was also only the first of
the
German
15-metre
championships, and the future will
surely show what the DG-200 is
made of. This then puts his 5th
place in perspective. However one
is glad that for Glaser-Dirks this
has been only a slight setback for
the DG-200. In the meantime
production of the series has started.
By the time that Aerokurier visited
Bruschal at the end of October
seven machines had already been
delivered.
Easier Than Expected
Because the wings of a flapped
glider are more difficult to fit due
to the integrated flap mechanisms,
and because the required strength
naturally makes them somewhat
heavier that with standard gliders,
rigging
usually
requires
the
assistance of strong men! But it is
here that the DG-200 collects its
first plus points! The comparatively
light wings of 65 kg each and their
problem-free
entry
into
the
fuselage enables rigging to be done
with the assistance of one wing
trestle. To demonstrate how easy it
is a team was brought in to rig the
glider, in this case Mr. Dirks and
Mr. Glaser in person, and it took
them less than 7 minutes!
With an unladen weight of
approximately 240 kg the DG-200
is easily inside the weight limits of
the new 15-metre class. Since
competitions are increasingly being
decided
in
weak
weather
conditions, it is of just as great
importance to have a low fullyequipped weight, and thus as low a
minimum wing-loading as possible,
as it is to have as high a maximum
wing-loading as possible for when
conditions are good. But getting
back to rigging. This is simplified
still further by the fact that for each
wing it is only necessary first to
support their weight on the two
drag pins and afterwards the two
main pins can be comfortably be
pushed home.
The aileron and airbrake linkages
are
accessible
through
an
inspection hatch in the upper
surface of the fuselage and are
connected using l’hotellier balland-socket connectors with sliding
locking cams. The flap connections
are made automatically.
The method for interconnecting the
flaps and ailerons and the range of
these controls is one of the wellkept secrets of any entrant to the
15-metre class. Past experiences
with flapped aircraft have shown
that it is not so simple to find the
ideal solution. With the DG-200
the interaction between ailerons
and flaps is such that operation of
the ailerons results in a differential
deflection of the flaps by
approximately 40% of the aileron
travel. The control mechanism is so
well-designed that in flap positions
of 0o and all negative positions, full
aileron travel is obtained whilst
with increasing positive flap
deflection, whilst aileron deflection
is steadily reduced, maximum
control is retained. The best way to
understand the interaction of flap
and aileron is to study them on the
ground before entering the cockpit.
Another critical aspect of flapped
aircraft design is in the fuselage to
wing joint. With the DG-200
special efforts have been made to
ensure that in each flap setting the
flap fits snugly against the
fuselage. Above all during the
design of the wing-fuselage joint,
examination of the test results have
shown that this is an area in which
great advances have been made.
Lastly when rigging, connecting
the elevator is just as usual. The
conventional elevator of the DG200 is easy to connect and there is
a small inspection panel built into
the top surface of the rear stabiliser.
It is particularly satisfying to note
that after the elevator has been
rigged the control connection is
inaccessible and cannot be knocked
or disconnected accidentally.
The DG-200 fuselage is to all
intents and purposes copied from
the
DG-100G
to
reduce
development costs. The tall
undercarriage with its largediameter wheel both guarantees
excellent ground-clearance and at
the same time absorbs bumps so
effectively that one might be led
to believe that the DG-200 has
sprung suspension. Additionally,
the particularly broad tread of the
ground-wheels will likely be a
benefit when landing on soft
ground.
As in the design, and in the same
way as for the DG-100, GlaserDirks are innovative in their
manufacturing methods. All the
parts of the DG-200 are annealed
directly in the mould. No use is
made of economical castings of
different materials, but instead all
of the DG-200 fittings are
implemented as steel welded parts
or milled from solid aluminium.
Whilst looking at the DG-200 it is
easy to forget that Glaser-Dirks is
the youngest manufacturer in the
to the midship-mounted seat pan.
Firm founder Glaser (right) having a brief discussion with the author of this
report, Bernd Malzbender, at the launch-point
German marketplace. Starting with
their DG-100 introduced a few
years ago, this newcomer has really
‘arrived’ from a zero point as an
accepted manufacturer. Again,
during the same period more
established, larger manufacturers,
steeped in tradition, have thought
more in terms of a reduction in
capacity rather than an increase. In
this critical market situation when
it is important to have your feet
planted firmly on the ground, a
technical achievement is not the
same thing as a business success,
and one can only congratulate this
new company from Bruchsal on
their undertaking.
An Athletic Entry!
The cockpit, with its two-piece
extended canopy, grips your body
snugly from the pointed nose back
Since all of the frames are
constructed from GRP they have a
substantially stronger connection to
the fuselage, according to Wilhelm
Dirks, than for example wooden
frames would have. On the lefthand side a narrow tunnel carries
the airbrake, flap and undercarriage
control linkages.
At first sight the DG-200 is easily
recognisable, as with its sister
models, by the very low-cut
cockpit which inevitable requires
an exceptionally large canopy. The
rear portion, which includes the
head restraint, hinges up for entry.
To enter one needs to pull in the
belly and without standing on the
seat-pan ease the feet over the high
thigh support and along past the
instrument mushroom to their
position on the rudder pedals. Once
seated in the cockpit however, one
finds
it
roomy
and
very
Horizontal stabiliser connection of the DG-200
advantage not to be underestimated
when launching in longer grass or
even during an outlanding in a
medium cropped field.
comfortable. There is ample head
and shoulder room and as well as
the simple rudder pedal adjustment,
an inflatable air cushion behind the
backrest enables one to tailor the
seat for comfort.
The left hand falls easily to the flap
lever with its six position detents.
This sounds more confusing than it
is in practice because in actual
flight only three positions are really
needed, the remainder being for
‘unusual situations’ and for takeoff
and/or landing. Since the flap lever
is mounted quite high, the lower
arm does not naturally fall on the
lower linkage tunnel, which
anyway is too narrow to make for a
particularly comfortable armrest.
Excellent Ground-Clearance
The first launch is a success,
problem-free despite a light
crosswind. The weight on the
tailwheel, the large rudder and the
very effective lateral control
prevent
any
tendency
to
weathercock. Also at the start of
the run the high ground-clearance
proves a great advantage since it
makes it longer before a wingtip
touches the grass and the ailerons
take effect quite early. This is an
Whilst still rolling I move the flaps
from 0 o to plus 4 o whereupon the
aircraft immediately takes off. You
can immediately tell that the DG200 has a very, very effective
elevator – just as sensitive as
earlier fibreglass aircraft. During
the entire ground-roll one needs to
be aware of this characteristic; one
can hardly afford to take one’s eyes
off the winch for more than a few
seconds without running the risk of
pulling the nose to high or too low.
During the climb I raise the
undercarriage. The undercarriage
lever is quite small and tucked
underneath the airbrake lever and
in using it my hand strikes the trim
button which is carried on a rod
directly behind it. It takes less
effort than I had originally
expected
despite
the
large
mainwheel.
But to continue with the first flight
impressions, the large canopy
extending to the pointed nose
makes for outstanding visibility.
But with this first flight the canopy
frame, where the hinged rear
section meets the forward fixed
section and which crosses the field
of view, perturbs me. After a few
flights however one becomes
accustomed to this obstruction.
Effective Ventilation
Another positive impression is
gained in the first few minutes of
flight – what a quiet aircraft this is.
The
hinged
canopy
closes
absolutely excellently. No hiss or
whistle betrays a leaky spot. The
hermetically sealed undercarriage
compartment
resists
any
undesirable airflow through the
fuselage. As anticipated, at 900
metres the canopy begins to mist
up – a welcome opportunity to test
the effectiveness of the ventilation.
The ventilation control knob is
somewhat
inconveniently
positioned closely under the
canopy frame on the right-hand
side. But this inconvenience does
not impair the effectiveness of the
ventilation. After few seconds the
entire canopy is clear again.
Because the air outlet sends the air
sideways directly at the canopy, the
ventilation is perfectly draughtfree, which is a particular
advantage for Spring and Winter
flying.
Great Flight Stability
The late Autumn mild weather
conditions naturally limits the
gliding possibilities but at least in
calm air one can become
acquainted
with
the
glider
particularly well. I get underneath a
small cumulus, unfortunately it is
disintegrating and also the last of
the day, and with the flaps set to
plus 8o try to squeeze yet another
few metres out of this dying cloud.
Trimmed back I find her as steady
as a rock. The rudder is well
balanced and the rudder forces
small. So for a while I am still
climbing and I can tell you that the
glider can if necessary be pulled
back to around 70 kilometres per
hour without instability or stalling.
With a turn reversal rate of
between 3 and 3.5 seconds from
45o to 45o at an indicated speed of
around 90 kilometres per hour the
DG-200 is quite agile. Even with
full aileron applied in the turn, the
large rudder (NAC profile) pulls
the yawstring inwards, underlining
its effectiveness.
Stick Held Back
As one drops below the minimum
flying speed in both straight flight
(at approximately 65 kilometres per
hour) and when circling, the onset
of the stall is briefly indicated by a
slight vibration. The nose dips
gently below the horizon in a
nodding motion rather than a
genuine stall.. Even with the flaps
set to plus 8o the ailerons remain
fully effective. It is only after
repeated attempts that the DG-200
is coaxed into a spin and, although
she rotates quite flat, she
automatically drops out again.
With negative flap, as expected, the
glider stalls somewhat more
violently but still the ailerons
remain fully effective.
These
altogether
gentle
flight
characteristics, which might almost
be called docile, are surely the
result of using the Wortmann
flapped profile fx-67-k-170 which
however is not modified into the
thinner k-150 at the outer wing as
is more usual but is continued right
up to the wingtips. The wing itself
is smooth and well-finished. The
special interconnection of the flaps
and ailerons means that when
flying slowly the ailerons do not
alter the deflection of the flaps.
High-Speed Flight
The highly-polished wing proves
its high efficiency however only in
high-speed flight. Set the DG-200
at 190 kilometres per hour, set the
flaps to minus 8o and ‘whoosh!’.
For racing starts and finishes there
is yet another ‘high speed gear’
with the flaps in the –12o position.
The air is quite calm and I push the
aircraft onwards to 270 kilometres
per hour. The wingtips are curved
upwards at this speed and the wing
is easily flexed upwards if it goes
through a small bump. Even at this
maximum speed the DG-200 is
easy to control without jerking. The
horizontal
parallelogram
construction of the stick makes it
impossible for pilot movements
due to bumpy flight to be
transferred to the controls.
Steep Approaches Possible
On final approach I select flap
position ‘L’. Together with the topsurface Schempp-Hirth airbrakes,
around 11 centimetres larger than
those of the DG-100, this makes for
an amazingly steep approach with
the airspeed remaining constant at
95 kilometres per hour. The
landing flaps are easily operated.
Rounding out from the descent I do
not notice anything unusual from
the ground effect The wheelbrake
which is attached to the stick
makes for an easy hold-off and
short roll.
One remaining point to note is that
amongst other things the DG-200
with proper instrumentation is
cleared for both cloud flying and
limited aerobatics.
In summary it can be said that the
DG-200 15-metre class glider,
contrary to widespread opinion is
not an aircraft only for experts and
experienced pilots. Agreed, it will
require some experience to get the
best out of the aircraft and to reach
the limits of this thoroughbred.
Equally certain though is that less
experienced pilots will find the
DG-200 problem-free and will be
able to fly it with little difficulty.
The DG-200 at present costs
35,500 DM plus VAT. In this price
are included the water ballast tanks
and a lacquer finish and there is an
extensive list of optional extras. At
the moment there are over 50 DG200s on order.
DG-200 Flap Positions
-12o
-8o
0o
+4o
+8o
L
Setting for very fast flight such as
during racing starts and finishes.
For speeds greater than 190 km/h.
Normal fast flight setting
Setting for best glide
Aerotow and winch-launch setting
Thermalling setting
Landing setting
DG-200 Datasheet
Model
Manufacturer
Class
DG-200
Glaser-Dirks
Flugzeugbau
15 metre class
Intended purpose
Number of seats
Wingspan
Length
Height at tail
Height of fuselage
Wing area
Aspect ratio
Wing profile
Empty weight
equipped
Additional load
Maximum water
ballast
Maximum takeoff
mass
Minimum wing
loading
Maximum wing
loading
Best glide
at speed of
at flying weight of
Stall speed
at flying weight of
Minimum sink
at flying weight of
at speed of
Maximum speed
on aerotow
on long tows
at winch-launch
Reprinted from the Aerokurier 12/1977 with their kind permission
&
Translated, not well I’m afraid, by Bob Adamson. 31st October 2002
High
performance
1
15 m
7m
1.45 m
0.81 m
10 m2
22.5
Wortmann FX67-K-170
240kg
100kg
110 kg
450kg
31 kg/m2
45 kg/m2
42.5
110 km/h
450 kg
62 km/h
310 kg
0.56 m/s
310 kg
72 km/h
270 km/h
120 km/h
195 km/h
100-110 km/h