engineering

PAR thrust

PAR thrust is a engineering 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 PAR thrust rather than just read about it. In short: Power Augmented Ram thrust (or PAR thrust for short) is the use of displaced air in enhancing the air cushion under the wings or body of what is normally a Wing In Ground-effect or WIG craft. The system can also be used in surface effect ships to increase their top speed.

Key takeaways

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

Reference excerpt

Power Augmented Ram thrust (or PAR thrust for short) is the use of displaced air in enhancing the air cushion under the wings or body of what is normally a Wing In Ground-effect or WIG craft. The system can also be used in surface effect ships to increase their top speed. The configuration can use either the exhaust gases from jet engines or propellers slipstream from either the main engines or special assist engines. This accelerated air is then either ducted, deflected or directed in such a manner that it will pass underneath the wing or body and assist in the creation of an air cushion. The purpose of using PAR thrust is to allow the craft to take off at lower speeds than those required if the system was not used. Some craft only use PAR thrust during takeoff; notable examples of this are the KM and Lun Ekranoplanes that situated their jet engines forward of the wing and deflected the thrust downwards under the wing. Once airborne and at a speed where sufficient lift was generated by the wing alone, the deflection could be removed. The KM required 10 turbojets to have enough power to take off, 8 of them operating in PAR mode; once in level flight, the engines could be throttled back extensively or some of them even shut off. A notable spin-off of this technique was the A-90 Orlyonok ekranoplan, which was powered in flight by a massive Kuznetsov NK-12 turboprop (by far the most powerful ever built), and required two large turbofans embedded in the nose for take-off, whose ducts pointed permanently downwards under the wings to provide PAR thrust. These engines were shut down during flight to reduce fuel consumption. Some other craft such as Burt Rutan's PARLC (Power Augmented Ram Landing Craft), Russian Strizh PE-201, Volga 2, Ivolga and other WIG craft use this system. Boats that use this system (surface effect ships) require permanent use of PAR thrust in order to achieve enough lift for normal operation.

References

Worked examples

Example 1 — a first encounter with PAR thrust

Start with the simplest possible case. Write down what PAR thrust claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, 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 PAR thrust 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 PAR thrust 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 PAR thrust

In research: PAR thrust appears in engineering 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 PAR thrust 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: PAR thrust is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aerodynamics, so understanding it makes those chapters shorter.
In everyday life: Look for PAR thrust 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 PAR thrust in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what PAR thrust 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 PAR thrust out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is PAR thrust in simple terms?

Why does PAR thrust matter?

Because it connects several engineering 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 PAR thrust?

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 PAR thrust.