Pratt & Whitney R-1690 Hornet Aircraft Engine Manuals Collection

This is a comprehensive, curated collection of original technical documentation for the Pratt & Whitney R-1690 Hornet — one of the most significant American radial engines of the interwar era. From illustrated parts catalogs to overhaul manuals and service handbooks, this collection provides the foundational reference material for historians, restorers, and A&P mechanics working with surviving Hornet-powered aircraft.

Definitive Collection with Free Lifetime Updates: This is a living collection that we continuously expand and refine. As we acquire additional R-1690 Hornet documentation, technical bulletins, or variant-specific materials, we update this collection and provide free lifetime updates to all purchasers. Your one-time purchase guarantees access to all future additions and improvements to this collection.

Historical Note

The Pratt & Whitney R-1690 Hornet was born from a simple ambition: build a bigger Wasp. First run on June 16, 1926, and entering production delivery by March 1927, the Hornet was conceived as a direct evolution of the R-1340 Wasp — scaling up displacement to 1,690.5 cubic inches across nine air-cooled cylinders arranged in a single-row radial configuration. The result was an engine that would define American air power through the late 1920s and 1930s.

Manufactured by Pratt & Whitney Aircraft Company in East Hartford, Connecticut, the Hornet delivered between 525 hp and 800+ hp depending on variant, with later models approaching 1,050 hp. Its engineering was notable for its enclosed valve gear, built-in supercharger, forged aluminum crankcase, and rear-grouped accessories — a layout that simplified field maintenance in an era when engine reliability was still a frontier challenge.

The Hornet powered some of the most iconic aircraft of its generation. In military service, it drove the Martin T4M torpedo plane — enabling the first practical carrier-based torpedo operations — as well as the Keystone B-3A heavy bomber, Douglas O-38 observation aircraft, Martin B-12, and Vought O2U Corsair. In civilian aviation, it was the powerplant of choice for the Boeing 80 trimotor airliner, the Sikorsky S-42 Pan American Clipper flying boat, and the legendary Gee Bee racing aircraft. Its influence extended internationally: the BMW 132, the primary powerplant of the Luftwaffe's Junkers Ju 52 transport, was a licensed German development of the Hornet, and the Fiat A.59 was its Italian counterpart.

Approximately 2,944 units were produced between 1926 and 1942, including licensed versions. The Hornet was eventually superseded by the more powerful R-1830 Twin Wasp, but its legacy endured through its licensed derivatives, which continued to power aircraft well into World War II and beyond.

Today, surviving R-1690 Hornets are museum pieces or rare airworthy examples in vintage restoration projects. The engine remains FAA-certified under historical Airworthiness Directives, with the Type Certificate held by Pratt & Whitney (RTX Corporation).

Manuals Included in This Collection

• Pratt & Whitney R-1690 Wasp C, C-1, D-1 / Hornet A-2, B, B-1, C, C-1, D, D-1 — Aircraft Engine Illustrated Parts Catalog
• Pratt & Whitney R-1690 Wasp A, B, C / Hornet A, A-1 — Aircraft Engine Illustrated Parts Catalog
• Pratt & Whitney R-1690 Hornet — Aircraft Engine Overhaul Manual
• Pratt & Whitney R-1690 Hornet — Aircraft Engine Handbook (Service Instructions)
• Pratt & Whitney R-1690 Wasp C, C-1, D-1 / Wasp Junior A / Hornet A-1, A-2, B, B-1, C, C-1 — Aircraft Engine Illustrated Parts Catalog (1933)

This collection spans the principal production variants of the R-1690 family, covering the Hornet A through D series and associated Wasp variants, with documentation dating from the late 1920s through the early 1930s — the engine's primary production and operational era.

Engineering Norms and Standards

The R-1690 Hornet was designed and manufactured to Pratt & Whitney's internal engineering standards of the late 1920s, which drew heavily on US Army Air Corps and US Navy procurement specifications. Key engineering norms reflected in these manuals include:

• Single-row, 9-cylinder air-cooled radial architecture with bore 6.125 in (155.6 mm) × stroke 6.375 in (161.9 mm)
• Displacement: 1,690.5 cu in (27.7 L); compression ratio 6.0:1 (varies by model, e.g. 5.0:1 on R-1690-5)
• Operating weight approximately 1,014 lbs (460 kg) dry; fuel grade 73–87 octane gasoline
• Built-in supercharger with two-piece crankshaft and solid master connecting rod
• Rear-grouped accessories for simplified field maintenance
• Military designation system: R-1690-1 through R-1690-54 series covering Army and Navy variants

Specialized Documentation

For operators of airworthy R-1690 Hornets, supplementary regulatory and service data is available through:

• Service Bulletins (SB) & Alert Service Bulletins (ASB): Tracked via the Pratt & Whitney MyP&WC Power Portal, searchable by engine model
• Time Between Overhaul (TBO) Bulletins: Define recommended overhaul intervals for continued airworthiness
• Airworthiness Directives (ADs): Legally enforceable FAA regulations under 14 CFR Part 39; historical ADs remain applicable to any airworthy R-1690

Where to Find Additional Documentation

• Official Support: Pratt & Whitney (RTX Corporation) — Type Certificate holder; MyP&WC Power Portal for current SBs and ADs
• Historical Archives: Smithsonian National Air and Space Museum, Deutsches Museum (Munich), Early Engines type clubs and warbird forums
• Specialty Vendors: Overhaul shops specializing in vintage radial engines; Online Aviation Library for additional historical documentation

Format & Delivery

All documents are delivered as high-resolution digital PDF files, optimized for screen viewing and print. Files are organized by document type and variant for easy reference. Instant download upon purchase — no shipping required. Compatible with all standard PDF readers on desktop, tablet, and mobile devices.

These documents are provided for historical reference and research purposes only. Always consult the current Type Certificate holder and applicable regulatory authorities for airworthiness decisions. No guarantee of completeness or currency is made. All trade names and trademarks are the property of their respective owners. Copyright © Sicuro Publishing.