physics

Gyro gunsight

Gyro gunsight is a physics 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 Gyro gunsight rather than just read about it. In short: A gyro gunsight (G.G.S.) is a modification of the non-magnifying reflector sight in which target lead (the amount of aim-off in front of a moving target) and bullet drop are calculated automatically. The first examples were developed in Britain just before the Second World War for use during aerial combat, and more advanced models were common on Allied aircraft by the end of the war.

Key takeaways

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

Reference excerpt

A gyro gunsight (G.G.S.) is a modification of the non-magnifying reflector sight in which target lead (the amount of aim-off in front of a moving target) and bullet drop are calculated automatically. The first examples were developed in Britain just before the Second World War for use during aerial combat, and more advanced models were common on Allied aircraft by the end of the war. The amount of lead required to hit a target is a function of the rate of turn of the attacking aircraft and the range to the target. The former is measured using a gyroscope in the sight, while the latter is estimated by the pilot by moving a dial or pointer so that a reticle in the sight matches the wingspan of the target. Post-war models added a small radar to automate the range measurement; these are known as radar gunsights. Gyro sights usually contained more than one reticle to assist in proper aiming: a fixed one, often just a dot, signifying the direction the guns are pointing, a moving one showing the corrected aiming point, and a ring to match to a target plane's known wingspan. A particularly advanced model, the K-14 found in the North American P-51 Mustang, had separate projectors and displays for air and ground attacks.

History In 1936 Royal Aircraft Establishment scientist Leslie Bennet Craigie Cunningham suggested using a gyroscope's resistance to rotation to modify the aiming point in a gun sight to compensate for deflection caused by a turning aircraft. This arrangement meant the information presented to the pilot was of his own aircraft, that is the deflection/lead calculated was based on his own bank-level, rate of turn, airspeed etc. The assumption was that the flight path was following the flight path of the target aircraft, as in a dogfight, therefore the input data was accurate enough to provide useful output data to the pilot.

British developments

Mark I

After tests with two experimental gyro gunsights which had begun in 1939, the first production gyro gunsight was the British Mark I Gyro Sight, developed at Farnborough in 1941. To save time in development the sight was based on the already existing type G prismatic sight, basically a telescopic gun sight folded into a shorter length by a series of prisms. Prototypes were tested in a Supermarine Spitfire and the turret of a Boulton Paul Defiant in the early part of that year. With the successful conclusion of these tests the sight was put into production by Ferranti, the first limited-production versions being available by the spring of 1941, with the sights being first used operationally against Luftwaffe raids on Britain in July the same year. The Mark I sight had a number of drawbacks, however, including a limited field of view, erratic behaviour of the reticle, and requiring the pilot/gunner to put their eye up against an eyepiece during violent manoeuvres.

Mark II

Production of the Mark I was postponed and work started on an improved sight. Changes involved incorporating the gyro adjusted reticle into a more standard reflector sight system, a non-magnifying optical sight that had been in use since 1918. Reflector sights consisting of a 45-degree angle glass beam splitter that sat in front of the pilot and projected an illuminated image of an aiming reticle that appeared to sit out in front of the pilot's field of view at infinity and was perfectly aligned with the plane's guns ("boresighted" with the guns). The sight sat some distance away from the pilot, so it was safer to use and didn't impair the pilot's field of view. The optical nature of the reflector sight meant it was possible to feed other information into field of view. In the reflector sight version, range was measured by comparing the wingspan of the target seen through the sight to a pre-set number. The pre-set number was selected via a large dial on the front of the sight, and the range was then measured by turning another dial on the aircraft's throttle. This new sight became the Mark II Gyro Sight and was first tested in late 1943 with production examples becoming available later in the same year. Ferranti built a new factory in the Crewe Toll area of Edinburgh, Scotland to build the sights. This factory would later go on to be the centre for Ferranti's long history in radar development. The Mark II was also subsequently produced in the US by Sperry as the K-14 (USAAF) and Mk18 (Navy). The K-14 included two projector systems for the reflector sight, one with gyro correction for attacking aircraft, and a second for attacking ground targets. It was otherwise similar to the British models, although the dial for adjusting the target size was moved to the left side of the sight instead of the front. The area where the Mark II had the dial was replaced by a moving scale that indicated the current range to the target, along with a large pad that prevented pilot head injuries in the case of rapid deceleration. The radar-aimed AGLT Village Inn tail turret incorporated a Mark II Gyro Sight and this turret was fitted to some Lancaster bombers towards the end of World War II.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Gyro gunsight

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

In research: Gyro gunsight appears in physics 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 Gyro gunsight 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: Gyro gunsight is common in secondary-school and first-year university syllabi. It links to neighbouring topics British inventions, Ferranti, Military optical devices, so understanding it makes those chapters shorter.
In everyday life: Look for Gyro gunsight 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 Gyro gunsight in 20 minutes

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

Frequently asked questions

What is Gyro gunsight in simple terms?

Why does Gyro gunsight matter?

Because it connects several physics 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 Gyro gunsight?

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 Gyro gunsight.