DG Flugzeugbau

DG-1000/1001 - The Two Seater from DG Flugzeugbau

This is a chronological report - from conception to maiden flight - of the development of our new two seater. Please have a read of this exciting story!

  • The ASK 21 was considered to be the ideal glider for flight training: robust, docile, and suitable for aerobatics.
  • The Duo-Discus was the most modern two seater and was designed especially for cross-country flying.
  • The DG-505 ORION was multitalented and combined good training capabilities, and very good performance in both cross-country and aerobatic flying.

When we got together to discuss the long term plans for DG Flugzeugbau. During these discussions it became clear to us that we could design and construct a glider that combines all the positive characteristics of the three models mentioned above.

The result was a plan for a two seater glider, the DG-1000 - and from 2009 on the DG-1001.

The Airfoil

The selection of an appropriate wing section was a collaborative event which occupied many well known professors and their respective aerodynamic labs for many weeks.

The final result is a laminar wing section designed by Horstmann/Quast from DLR Braunschweig. This section was reviewed and measured at Stuttgart University. The Technical University of Delft then completed the design with the addition of winglets and by optimizing the wing- fuselage intersection.

In the end, two possible wing sections were left to choose from. One of them represented ultimate performance at best L/D speed , however it showed a strong drop in performance at higher speeds and likely possessed nasty stalling characteristics.

The other option was slightly less efficient at best L/D, however much better above 160 km/h. This was combined with very docile stalling characteristics and low bug- and rain sensitivity.

We believe that the small advantage of the glide ratio of the first profile is unattainable in normal flight, and that the docile stall characteristics and the low bug- and rain sensitivity of the second option were much more important.

Naturally, we chose the second wing section.

Now that the Maiden Flight is done, we can already say that these theoretical prophecies were totally fulfilled!

The Wing

The DG-1000 can be flown with 2 wing-spans. For easier rigging each wing features a parting device at y=8600 m that is, at about the 17.2 meter point. For flying at the 18 meter span a set of 0.4 meter long wing tips with "miniwinglets" are added (similar to the standard DG-800 18m tips). This configuration is designed to produce good rolling qualities and predictable flight behavior.

For cross-country flying the 20m wing tip extensions with integral winglets are added.

Doubtless, the wing-planform will show some similarities to the Duo-Discus. It should be noted, however, that the selection of planform and dihedral was lead principally by aesthetics. Whether or not the wing has a single or double contour break, or if it is bent forwards or backwards makes little difference in performance.

So of course we designed our glider to be sleek and pleasing to the eye. A perfect marriage of aesthetics and performance. We like to think of the DG-1000 as an aerodynamic work of art!

In addition the four-part trapezoidal wing of the DG-1000 has a small advantage over a two-part trapezoidal plan form at low speeds.

The carbon wings of the DG-505 are not heavy at all. But the weight of each DG-1000 wing is about 8 KG (!) less, (approx. 89 KG! )

The Fuselage

The fuselage originates from the DG-505 and incorporates a variety of enhancements. The positive characteristics were carried over . The high seating position of the rear seat was not changed. This gives the rear pilot (usually the flight instructor) an excellent view. That is also why we have decided to keep the two-piece canopy. You can read our thoughts on why not to change to a single canopy on our website. Safety reasons were the main factor in our decision.


 

Another important change was to the landing gear:

We have designed a shock-absorbing, sophisticated new mechanism providing high comfort.
The problem with two seaters is that the rear pilot sits exactly where the main wheel should be. As a result the glider is nose heavy on the ground. For this reason , most tandem two seaters have a nose wheel as well as a main wheel. This is a disadvantage for winch launching, as the tail wheel can often hit the ground when the winch cable tightens. This is not necessarily good for the structure, and is very unsettling for the flight student because the glider's attitude changes suddenly.

Our wheel extends forward from the landing gear compartment beyond the centre of gravity. The DG-1000 therefore tends to sit up, even with a pilot in the front cockpit. The sudden pitch up on winch launch is avoided because the glider always rests on the tail wheel.

The big spring gives an excellent comfort during taxiing and the wheel comes with a hydraulic disk brake.
The higher weight for the tail wheel is easy to handle with a towing device made by COBRA-Trailer.

To remember: In those days the DuoDiscus came with a main wheel without any spring - like a Ka 7 or Ka 13!

The Tail plane

The sailplane has also been completely redesigned with new profile sections and optimized to the size of the wings. We want to install a small fin tank to compensate the C.G. shift due to water ballast in the wings.

Furthermore we thought that it should be easy to adjust the C.G. depending on the cockpit loads in order to achieve the best handling and performance characteristics.
There is a large difference between two heavy adults or one light juvenile flying, especially if they fly right  after one another.

Therefore we created a compartment in the vertical fin for ballast weights which is accessible via a removable panel. After removing the panel you can easily install one to nine brass weights into specified compartments to adjust the C.G. point as required..

Flight Performance

We believed we could predict that the DG-1000 would feature noticeable performance advantages in comparison to other gliders:

  • The wing section is state-of-the-art.
  • The wing-fuselage intersection was optimized for optimalboundary layer conditions with special airfoils in this area.
  • Winglets are standard for the 20m span which performance-wise will result in a wingspan of approx. 21 meters.
  • The drag of the nose wheel has been eliminated.
    Exact performance figures are available since flight comparison tests have been done. A flight with the Duo Discus proved these results!

The theoretical calculations  looked very promising:

  • The min. rate of sink should be 0.51 m/sek at 28 kg/m2 wing loading (Solo flying).
  • The best glide ratio was calculated at 1:46.5 with 42.8 kg/m2; (max. weight)!

Motorization / Wing flaps /22 Meter span

From the beginning we had planed to offer the DG-1000 with an engine later on - as a self-launcher or as a Turbo-version. We had just finished the development of the DG-505MB, which was the only motorized two seater glider in its class on the market. At the moment we develop, design and type certify a motorized self-launching DG-1000M, not to mention that the available production capacity for the "normal version" are at its limit.

There are also plans to develop a version with wing flaps... but not in the near future.
There will not be a version with larger wingspan (22 meters or more). To prepare for a span larger than 20m, the necessary reinforcements of the inner wing panels would result in higher mass for all versions and reduced rigging comfort.

Because of "Murphy's Law" the maiden flight did not occur until July 28th, 2000. 

During the development of the real DG-1000 many R/C models already were built.  All are very nice!  

On April 14th the spectacular wing test to destruction was conducted in Stuttgart.

Pricing:

The price for the DG-1000 includes:

  • A  modern airfoil with especially good gliding characteristics. This has been convincingly proven.
  • The standard-equipment winglets
  • A trim box in the fin for quicker and precise C.G. adjustment including electronic indicator in the cockpit
  • A main gear situated in front of the C. G. Even with a solo pilot in the front cockpit, the glider rests on the tail wheel.  This prevents the tail slamming down in the initial acceleration of a winch launch.
  • two wing tip wheels
  • a quick trimming device

Marketing:

Since 2009 we offer five models of the DG-1000 family:

DG-1001S

This is the standard model with a 20 m span, winglets, retractable main gear (as described above, also electrically operated), trim box, and water ballast. Additional there is an option for the landing gear of the well known DG-505 Orion (look at the photo, please!).

DG-1001S-18/20

For this variation wing tips for an 18 m wingspan are available.  1.4 meter extensions, including winglets are available as options. The 18 configuration is ideal for clubs that want to teach. And - as we already know - in this version the DG-1000 is a very good aerobatic trainer.
The extensions transform the ship into a high-performance cross-country machine.

DG-1001S Club

This intended for clubs wanting a less expensive entry model.  The span is fixed at 18 m, the gear is non retractable, and there is no water ballast system.
Although the price is higher than that of the competition model ASK-21, the 1000 has an airfoil which is newer in design by about 20 years, has a trim box in the fin, and carbon wings which make rigging  considerably easier and the automatic control system connectors.

As an extra, the Club Model can be ordered with "normal" retractable gear, water ballast system, and with removable tips.  This gives the option of  later  adding the wing extensions, including winglets thus giving you a complete DG-1001S-18/20m!
If you want to retrofit the wing parting or retractable gear later, you will have additional cost.

DG-1001T

The motorized version as a Turbo with a wing span of 18 or 20 m is available since spring 2005.

Another possibility might interest instructors.  They often complain that fiber glass two seaters can not be used for spin training.  But when students later fly a single place glider, they can easily get into a spin by mistake and have not been taught proper recovery techniques.
The DG-1000, with the help of the trim box and fin tank, can be set up with a suitably rearward C.G. for spin training.

 

DG-1001M

The motorized version as a Self Launcher with a wing span of 20 m is available since autumn 2009.

So we are offering a complete line of two-place gliders from the
DG-1001 Club to the DG-1001M which should fill every possible need.


The different types:  

x = Standard                 o = Option                    -  = not possible

 

DG-1001S

DG-1001S-18/20

DG-1001 Club

DG-1001M

DG-1001T

retractable gear without front wheel

x

x

o

o

x

retractable and electrical gear without front wheel

  x

  x

  o

x

  x

retractable gear with front wheel

o

o

o

-

o

fixed gear 

-

-

x

-

-

wing parting

x

x

o

x

x

18 m Wingtips

o

x

x

-

o

20 m tips

x

x

o

x

x

water ballast system

x

x

o

o

x

aerobatic capability

x

x

x

-

x


The First Flight

Subject:   DG-1000
Date:        Thurs, Jul 27,2000
 

Dear Friedel.

IT  FLIES - AND VERY VERY WELL!

Wilhelm Dirks made the first flight with the DG-1000 today at noon from Forschheim.

There were absolutely no problems and he was very satisfied.  The handling of the glider was described by everybody who flew with him as very comfortable.  The flight performance, in comparison to the other two seater is clearly better especially at high speed.

The sensitivity of the wings to rain or bugs was easy to observe in the summer weather and is also much better than the comparison glider in this respect.

Even at this time, with everything not quite finished and needing a bit of fine tuning, the first impression of the glider is simply outstanding!

Always happy landings,
Swen


Subject:  DG-1000  First flight
Date       Fri.  July 28, 2000
From      Wilhelm Dirks

Dear Friedel,

Something has actually worked as planned.
Yesterday (Thursday) we made the first 5 flights with the DG-1000.  It flew without problems and I must say, it is a first class machine with very light and harmonious controls.  The flight performance is very good especially at high speed.  The performance of the DG-1000 is noticeably better than  the other two seater in light rain.
A comparison flight with the Duo Discus is planned for week after next.

With best regards,   Wilhelm


WOW -  MY  BEST  WISHES  TO  YOU  TWO!!!

and - as some people reported - nobody had ever seen Wilhelm Dirks so happy as after landing of that flight!

The DG-100 is the first glider that I, as managing director and owner since 1996, have been through from beginning to end.  You can imagine how happy I am at this moment.

From my heart, I wish that all pilots will have a chance to fly this apparently wonderful device and I wish them

Always Happy Landings,
Friedel Weber


DG-1000 certified

At March 12th, 2002 the German FAA (Luftfahrt-Bundesamt) issued the certification of the DG-1000.
Now the glider is certified according to the following specification (in German):

dg1000-musterzulassung.pdf  

DG-1000

P.S.  This is being written in front of the toilette house on the Mather Campground 
on the South Rim of the Grand Canyon National Park / USA because my extension cord is so short!

Index DG-1000

DG-1000 vs Duo Discus – Comparison Flight
 


 


 


DG-1000 during the German Glider Pilot Day in Leipzig



Passenger and trial flights from the back seat

The new JAR-FCL3 rules regarding pilot medicals in Germany have meant for a number of older pilots that they are suddenly grounded and can now only fly in two-seaters from the back seat, even with a safety pilot.

At the same time trial flights in Germany for potential new student pilots were (probably as an “accidental” by-product) made substantially more expensive, as they now need to have a valid medical before they take up flying, i.e. even before their first solo.

We expect these two points to be reworked by the relevant authorities at some point, but in the meantime that doesn’t stop us from offering our very own solution of the problem:

The certification of the DG-1000 has been slightly modified, so that as of now you can fly any DG-1000S (glider) as P1 or “pilot in command” from the back seat, as long as the pilot is qualified and the glider equipped as necessary.

The first condition can be met by doing a few training flights from the back seat, with an instructor in the front seat. After all, apart from the slightly different view, flying from the back seat is much the same as flying from the front. As soon as the instructor is happy that the pilot can safely fly the glider from the back seat that’s it. The pilot can now fly from the back seat or from the front.

The second condition is met anyway as the DG-1000S has the same equipment in the back as in the front. Plus you can operate both the undercarriage and air brake levers from both seats in the same way.

The only restriction is that in the DG-1000T the engine must not be used when the pilot in command is in the back seat - otherwise the glider is equipped with to engine control systems.

This way any “old eagle” who is currently struggling to get his or her medical sorted can fly legally from the front seat, as long as a qualified gliding license holder accompanies him/her as a safety pilot.

And trial flights are possible as well, because the potential student pilot is declared to be just a passenger, and apart from the launch and landing the pilot can of course let the passenger hold the stick.

We have written a Technical Note about this, which will be published soon. We are happy that we are able to provide a significant contribution to the solution of these new problems that our sport is facing.

Translation: Claudia Buengen


Hi,
I find the discussion about which seat the responsible pilot occupies interesting and amusing.

In Australia it is absolutely routine for the Pilot in Command to occupy the rear seat. So much so that when two pilots share a flight in a two seater, the other people at the launch point will assume that the rear pilot is the PIC even if (for some strange reason) this is not the case. When taking passengers for a first flight, we would never put them in the rear seat unless it were dictated by weight and balance issues. It would be unfair to the passenger. They get a much more enjoyable experience from the front seat. They can see more. Most importantly the pilot can see what the passenger or student is doing. You can see if they are likely to play with the controls and you often get an early warning if they are getting air sick.

Aircraft type makes no difference to this practice even in the case of some machines where the undercarriage can only easily be lowered from the front seat, we just don't raise the wheel. I once flew a passenger who insisted on sitting in the rear seat. I found this to be quite difficult as I had less idea what was going on in the passenger's mind because I couldn't see him.

Brendan English.
Gliding Club of Victoria
Benalla Australia


Serial No. 100 is ready!

Mail March 16th, 2007:

Hello Friedel,

after 2,5 years of waiting the "SFG Giulini e. V." got the 100th DG-1000 today. The club is flying in Dannstadt and is very successful in the OLC. They will use our DG-1000T mainly for cross-country flights as well as for contest flying.

On the picture you can see the main sponsor, Dr. Ulrich Wagner, getting a bottle of Champaign. On my left hand side you see Charly Müller, one coach of Rheinland-Pfalz and quite a lot of pilot youngsters


 


Brochure of the DG-1001 Family
 

Other Articles of Interest:

 


DG-1000 - Impressions and Comments

 

Derek Piggott flies the DG-1000

 

DG-1001 Trim Box

 

Aerobatic Test flights of the DG-1000S/18m

 

DG-1001T - the sustainer version

 

DG-1000 hums