science

Sikorsky S-40

Sikorsky S-40 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 Sikorsky S-40 rather than just read about it. In short: The Sikorsky S-40 was an American amphibious flying boat built by Sikorsky in the early 1930s for Pan American Airways. During World War II they were used by the United States Navy for training.

Key takeaways

Sikorsky S-40 belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sikorsky S-40 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sikorsky S-40 from memory before moving on to harder problems.

Reference excerpt

The Sikorsky S-40 was an American amphibious flying boat built by Sikorsky in the early 1930s for Pan American Airways. During World War II they were used by the United States Navy for training. This was the first of flying clippers, large flying boats of the 1930s used for long distance air travel. More advanced designs soon followed, but the S-40 was a big step forward as it could carry 38 passengers as opposed to the S-38's eight.

Design and development

Sikorsky designed the S-40 in response to a request from Juan Trippe, president of Pan American Airways, for a larger passenger-carrying airplane. The S-40 could carry 38 passengers, a significant increase over the S-38's eight passengers. Wind tunnel testing of the S-40 started in October 1928, and models of the hull were tested in April 1929. The aircraft featured a pantry with an electric refrigerator and stove as well as a smoking lounge with book-ended mahogany wood paneling. Six life rafts were carried. Despite a significant size increase over the preceding S-38, the S-40 design was a conservative iteration of the smaller aircraft; the numerous flying wires and strut braces that were used in the exterior support framework caused significant drag and prompted Charles Lindbergh, retained as a consultant for Pan American, to tell Sikorsky "it would be like flying a forest through the air." Only three were built as Sikorsky began designing the more advanced and streamlined S-42 shortly after the S-40 entered service, based partly on input from Lindbergh. All three S-40s were built by the Vought-Sikorsky Aircraft Division of the United Aircraft in Stratford, Connecticut.

The first test flight occurred on August 6, 1931. The first aircraft was christened American Clipper by Lou Henry Hoover, wife of President Herbert Hoover, on October 12, 1931 at NAS Anacostia; after its christening, American Clipper flew around Washington, D.C. In 1935, all three aircraft were upgraded and re-designated as the Sikorsky S-40A. Upgrades included replacing the original 575 hp (429 kW) Pratt & Whitney R-1860 Hornet B engines with smaller displacement but more powerful supercharged 660 hp (490 kW) R-1690 Hornet T2D1 engines, eliminating the landing gear, and increasing the maximum weight slightly. Another source states the landing gear was removed soon after the type certificate was issued.

Operational history

Passenger carrying service was initiated on November 19, 1931, with a S-40 piloted by Charles Lindbergh and Basil Rowe, flying from Miami, Florida to the Panama Canal Zone with stops at Cienfuegos, Cuba; Kingston, Jamaica, and Barranquilla, Colombia. Igor Sikorsky, the aircraft's designer, was on board as a passenger. During that trip, Sikorsky and Lindbergh began working on concepts that were used in the succeeding S-42. The S-40 was Pan American's first large flying boat. American Clipper served as the flagship of Pan Am's clipper fleet and this aircraft model was the first to earn the popular designation of "Clipper" or "Pan Am Clipper". The three S-40s served without incident during their civilian lives, flying a total of over 10 million miles.

Navy Service They were retired around 1940 and turned over to the US Navy during World War II, who used them as trainers for four-engined flight instruction. Under Navy service, the aircraft were designated Sikorsky RS-4. (see also Sikorsky RS) Two of the S-40 were pressed into Navy service, and called RS-4. In July 1943, an RS-4 (752V) was coming in for beaching when it struck an unforeseen submerged rock, which damaged the wheel strut, which in turn caused a list that led to a pontoon striking a rail at the edge of the ramp. Beaching is when the flying boat is on the water, but brings its wheels down to come on to land, usually by a seaplane ramp. Another was damaged at Dinner Key in April 1943, and then returned to Pan-American by the Navy, however it was not returned to service but was used for spare parts.

List

Specifications (S-40)

Data from American airplane specificationsGeneral characteristics Crew: 6 crew Capacity: 38 passengers Length: 76 ft 0 in (23.16 m) Wingspan: 114 ft 0 in (34.75 m) Height: 23 ft 0 in (7.01 m) Wing area: 1,740 sq ft (162 m2) Empty weight: 23,000 lb (10,433 kg) Gross weight: 34,000 lb (15,422 kg) Fuel capacity: 1,066 US gal (888 imp gal; 4,040 L) Powerplant: 4 × Pratt & Whitney Hornet 9-cylinder radial engines, 575 hp (429 kW) each Performance

Maximum speed: 117 kn (135 mph, 217 km/h) Cruise speed: 97 kn (112 mph, 180 km/h) Stall speed: 56 kn (64 mph, 103 km/h) Range: 780 nmi (900 mi, 1,400 km) Service ceiling: 13,000 ft (4,000 m) Rate of climb: 700 ft/min (3.6 m/s)

Illustrations

Worked examples

Example 1 — a first encounter with Sikorsky S-40

Start with the simplest possible case. Write down what Sikorsky S-40 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 Sikorsky S-40 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 Sikorsky S-40 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 Sikorsky S-40

In research: Sikorsky S-40 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 Sikorsky S-40 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: Sikorsky S-40 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1930s United States airliners, Aircraft first flown in 1931, Amphibious aircraft, so understanding it makes those chapters shorter.
In everyday life: Look for Sikorsky S-40 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Sikorsky S-40” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Sikorsky S-40 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sikorsky S-40 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 Sikorsky S-40 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sikorsky S-40 in simple terms?

The Sikorsky S-40 was an American amphibious flying boat built by Sikorsky in the early 1930s for Pan American Airways. During World War II they were used by the United States Navy for training.

Why does Sikorsky S-40 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 Sikorsky S-40?

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 Sikorsky S-40.