by Ludwig Haslbeck
Published in the magazine “Segelfliegen”, May 2007
With the DG-100 the engineer and former Akaflieger W. Dirks, who together with the civil engineer Gerhard Glaser founded the company Glaser-Dirks, managed from the start with the construction of a successful single seater. Over 300 examples were built in various versions at Glaser-Dirks, and later at Elan from 1973, the last being the DG-100G with a one piece canopy and damped elevator.
(Wave flight with a DG-300 on a frozen Norwegian lake)
As a successor Wilhelm Dirks then developed the DG-300. Elan also produced these in Slovenia from 1983. Various versions were offered: in addition to the DG-300 with retractable undercarriage and blowing on the wing under surface, there was the DG-300 Club, which was also optionally available without retractable undercarriage, as well as the DG-300 Acro, which has a strengthened structure, and is suitable for aerobatic flight.
The final development was the DG-303, with a slightly modified wing profile and optional winglets- but these could also be retrofitted on the older DG-300. With these high speed performance improves, and slow flight qualities are optimised. The cockpit was also revised, with the canopy receiving a single jettison lever and a Roeger hook. As for the DG-300, the DG-303 was produced in various variants at Elan or AMS.When production finished in 2006 a total of 511 aeroplanes had been delivered.
The whole of the aircraft structure is made of glass fibre. In the standard version the blowing provides a closer envelope of flow, i.e. less separation, and therefore gives better performance. An exhaust pipe is located on the inside of the wing over approximately two thirds of the comparatively thick lifting surface, through which the air, provided by an intake on the underside, is blown through 900 tiny holes (diameter approximately 0.6 mm). Tests have revealed that up to about 150 km/h a reduction in drag is achieved, but at higher speeds hardly any difference can be noticed. One should also be aware that these small holes should not be closed up when polishing, leading to a loss in system effectiveness.
The winglets are easily installed, a small bolt engaging through a spring in the right position automatically.Attaching the wings is conventional, all control surfaces connecting automatically with the proven DG system. After a little practice connecting the elevator is easy, being mounted with a screw, which is secured with a wire.
The cockpit shows its similarity to its predecessor: the DG-300 also has a large deep canopy, which guarantees excellent vision. The built in T-shaped instrument console in the middle only restricts vision a little. To avoid reflections in the canopy, one should wear dark trousers. This is no bad thing as the sun will keep your legs warm!
Just as for the Glasfluegel aeroplanes, the DG-300 uses a parallelogram set of controls, which should be more insensitive to gusts.
Operational controls are standard: the lever for the very effective SchemppHirth airbrakes is on ones left- pulling further back brakes the large 5.00-5 wheel.
The water ballast and undercarriage levers can be found to the right. The latter is really small, and one must take good care that the extended undercarriage is really down and locked. Quite a few pilots must have experienced the wheel retracting on landing.
On asphalt runways, with the centre of gravity being ahead of the undercarriage bay, the underside of the fuselage will be ground away- very expensive! A TM improves the situation by using a spring to set the undercarriage lever more positively. Ground handling is improved with the tailwheel.
As concerns best glide ratio, the details are as follows: AMS quotes 1:43 to 1:44 according to wing loading. This value, which would correspond approximately to that of the ASW24, seems to be somewhat optimistic, as during comparative flights between the club DG-303 and my ASW24, I found the ASW to perform better. When circling in thermals, both aircraft are more or less equal, but the DG noses ahead since it has more forgiving handling at low speed, and climbs well. Overall the handling is very good natured, the rudder being well balanced, and manoeuvrability good, even if many find fault with the somewhat heavy ailerons.
Competition success came seldom to the DG-300 and DG-303. And yet the number of deliveries shows that the aircraft is held in high esteem, and justifiably so. It is not only in club use that the aircraft has proved itself. The DG-300 suits many pilots who are looking for a good value aircraft, with pleasant performance, which is comfortable.
With prices ranging from 25,000 to 30,000 Euros, used aircraft are clearly less expensive than the LS7, ASW24 or Discus.
It remains to be seen what effect a LTA from Autumn 2006 will have on values: when a damaged wing was being repaired, it was discovered that the company Elan had made a mistake during spar production. Even though to date this error has not caused an accident, operational limits (maximum speed and all up weight) have been restricted, and aerobatic flight is no longer allowed.
According to Hannes Zimmermann of ISS-Aviation, before the spar LTA, the price of an example lay between approximately 25,000 and 35,000 Euros, depending on hours flown, condition and level of equipment, e.g. with winglets. About six years ago there was hardly any demand for the DG-300, but since then the situation has changed, with there being many interested prospective purchasers. Naturally, prices have risen. As regards the consequences of the spar LTA on market and price, it is hard to tell. Hannes Zimmermann however does not think that much will change, as only maximum speed and all up weight are affected.
The DG-300 can be assessed as a solid club class aeroplane, ideal for clubs, with a reasonable price/performance ratio. It has no particular quirks, the quality of paint is mostly good, which as a rule is the case for DG aircraft. Apart from the most recent examples, the DG-300 has been unaffected by more serious TMs.
Holger Backs (DG-Flugzeugbau) Opinion on the Spar Problem.
The problem originated when the spar caps were directly laid into the wing skin during production. It can happen through production errors that some rovings exhibit slight waviness, and thus the calculated safety margin is no longer 100%. Although no accident can be put down to this production error, new more restrictive operational limits were calculated to be on the safe side again. This should only be a problem for a small minority of pilots, but more far reaching in comparison, is the fact that aerobatic flight is now prohibited, even for the Acro version. DG has tried quite a lot of options to develop an economical inspection, but unfortunately without success. The only safe check is to cut open the wing, but the expense of doing this would deter a lot of pilots. The first inspections did not result in further issues, so that with the wing closure, the operational limits could be set up again.Unfortunately the TM is valid for all DG-300 and -303, as it cannot be established which aircraft were produced defectively.