science

Glaser-Dirks DG-400

Glaser-Dirks DG-400 is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Glaser-Dirks DG-400 rather than just read about it. In short: The Glaser-Dirks DG-400 is a single-seat self-launching motorglider that was produced by Glaser-Dirks between 1981 and 1992. It was the first self-launching motorglider with retractable engine and propeller to be produced in large numbers.

Key takeaways

Glaser-Dirks DG-400 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Glaser-Dirks DG-400 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Glaser-Dirks DG-400 from memory before moving on to harder problems.

Reference excerpt

The Glaser-Dirks DG-400 is a single-seat self-launching motorglider that was produced by Glaser-Dirks between 1981 and 1992. It was the first self-launching motorglider with retractable engine and propeller to be produced in large numbers.

Development The cost of carbon-fibre had fallen enough in the late 1970s to allow its use in the wing spars of high-performance gliders. Glaser-Dirks introduced a carbon wing variant of the DG-200 about this time. Designer Wilhelm Dirks realised that the span, strength and very low weight of this wing allowed for a self-launching engine to be carried in the glider without an unacceptable penalty when soaring in weak conditions. The DG-400 was created as a result. It first flew in May 1981. The DG-400 uses the wings and most systems of the DG-202. It has a modified fuselage with a slightly enlarged tailcone and carbon fibre reinforcements to accommodate the engine, which is a relatively large unit with electric starter and electric retraction. This powerful installation, with a user-friendly engine control unit, made the DG-400 easier to operate than other self-launching gliders. As was typical for the time, the engine, propeller and supporting pylon constitute a single unit that extends into the airflow (in more recent self-launchers the engine usually stays inside the fuselage). The type may be flown either with 15 metre or 17 metre wingtips. The DG-400 was not aimed at competitions, but rather at leisure flying. Nevertheless, several World Gliding Records have been achieved flying this type.

Specifications (17 metre wings) Data from General characteristics Crew: 1 Length: 7 m (23 ft 0 in) Wingspan: 17 m (55 ft 9 in) Height: 1.4 m (4 ft 7 in) Wing area: 10.57 m2 (113.8 sq ft) Aspect ratio: 27.3 Airfoil: root:Wortmann FX-67-K-170-17; tip Wortmann FX-60-K-126 Empty weight: 305 kg (672 lb) Max takeoff weight: 460 kg (1,014 lb) Fuel capacity: 20 L (5.3 US gal; 4.4 imp gal) 50 L (13 US gal; 11 imp gal) with optional tanks in lieu of water ballast Water ballast: 90 L (24 US gal; 20 imp gal) Powerplant: 1 × Rotax 505 two-stroke retractable pylon mounted air-cooled piston engine, 32 kW (43 hp) Propellers: 2-bladed Hoffman fixed pitch propeller, 1.29 m (4 ft 3 in) diameter Performance

Cruise speed: 130 km/h (81 mph, 70 kn) economical 140 km/h (87 mph; 76 kn) max Stall speed: 63 km/h (39 mph, 34 kn) Never exceed speed: 270 km/h (170 mph, 150 kn) in smooth air 190 km/h (120 mph; 100 kn) in rough air 190 km/h (120 mph; 100 kn) on aero-tow 130 km/h (81 mph; 70 kn) on winch launch Range: 400 km (250 mi, 220 nmi) level flight 750 km (470 mi; 400 nmi) cruise/soar Service ceiling: 5,000 m (16,000 ft) g limits: +6 -4 Maximum glide ratio: 45 at 110 km/h (68 mph; 59 kn) Rate of climb: 3.90 m/s (768 ft/min) at 80 km/h (50 mph; 43 kn) Rate of sink: 0.5 m/s (98 ft/min) Wing loading: 43.5 kg/m2 (8.9 lb/sq ft) Power/mass: 0.0714 kW/kg (0.0433 hp/lb)

References

External links

DG-Flugzeugbau website Sailplane Directory DG400 pictures & details German Gliding Magazine

Illustrations

Worked examples

Example 1 — a first encounter with Glaser-Dirks DG-400

Start with the simplest possible case. Write down what Glaser-Dirks DG-400 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Glaser-Dirks DG-400 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Glaser-Dirks DG-400 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Glaser-Dirks DG-400

In research: Glaser-Dirks DG-400 appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Glaser-Dirks DG-400 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Glaser-Dirks DG-400 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1980s German sailplanes, Aircraft first flown in 1981, DG Flugzeugbau aircraft, so understanding it makes those chapters shorter.
In everyday life: Look for Glaser-Dirks DG-400 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Glaser-Dirks DG-400 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Glaser-Dirks DG-400 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Glaser-Dirks DG-400 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Glaser-Dirks DG-400 in simple terms?

Why does Glaser-Dirks DG-400 matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Glaser-Dirks DG-400?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Glaser-Dirks DG-400.