Republic P-43 Lancer & Seversky P-35 Engineering Drawings Collection

Rare and exclusive documentation. Comprehensive archive of original manufacturing engineering drawings and blueprints for the Republic Aviation P-43 A, B, C, D, E, YP-43 variants, Seversky P-35, and AT-12 series aircraft. This extensive collection contains authentic technical documentation from the original manufacturer, preserved from microfilm archives and now available in digital format.

Definitive Collection with Free Lifetime Updates

This is a living collection that we continuously expand and refine. As we acquire additional P-43 Lancer and Seversky P-35 documentation, technical bulletins, or variant-specific materials, we update this collection and provide free lifetime updates to all purchasers. Your one-time purchase guarantees permanent ownership and access to all future additions and improvements to this collection.

Collection Contents

• 11,200+ engineering drawing sheets from 13 digitized microfilm rolls (Rolls A–M)
• Sourced from the original 20-roll set; remaining rolls were not recoverable due to source microfilm degradation beyond recovery
• Complete index of drawing numbers for easy reference
• High-resolution TIFF and Adobe PDF formats
• Airframe structural drawings, component details, and assembly blueprints
• Original manufacturing specifications and tolerances
• Coverage: AT-12, P-35, P-35A, YP-43, P-43A, P-43A-1, P-43B, P-43C, P-43D, P-43E, P-43
• Film Index Number system: each drawing is referenced by roll letter + sequential position (e.g. G154 = Roll G, 154th drawing)

Historical & Technical Core Data

Engineering Analysis: Seversky P-35 and Republic P-43 Lancer

The Seversky P-35 and Republic P-43 Lancer represent a critical evolutionary bridge in American fighter design, spanning from the mid-1930s all-metal monoplane breakthrough to the high-altitude turbo-supercharged architecture that directly birthed the legendary P-47 Thunderbolt. Chief Designer Alexander Kartveli utilized a unified structural philosophy across both aircraft, emphasizing elliptical wings and deep forward fuselages designed to capture and route airflow.

Below is the synthesized engineering and performance profile compiled from historic flight test logs, aerodynamic reports, and technical manuals.

Aerodynamic Reports & Structural Design

• Wing Profiling: Both aircraft featured a fully stressed-skin, all-metal low wing utilizing a distinctively rounded, semi-elliptical planform. This maximized wing area while minimizing induced drag at high angles of attack.
• Surface Polish: The P-43 was one of the earliest USAAC fighters to extensively employ flush-riveting across primary lifting surfaces, drastically reducing parasite drag coefficients compared to the dome-riveted P-35.
• Ducting and Cowling: The YP-43 introduced a distinctive ovoid cowling to shift the primary engine air intake from the wing root to the lower chin. This unique ducting geometry was aerodynamically engineered to channel high-velocity air straight to the aft-mounted turbo-supercharger system.

Engine Technical Notes

• P-35 Powerplant: Driven by a single Pratt & Whitney R-1830-9 Twin Wasp 14-cylinder air-cooled radial engine, producing 850 hp at takeoff. It utilized a single-stage, mechanical supercharger optimized for low-to-medium altitudes.
• P-43 Lancer Powerplant: Upgraded to a Pratt & Whitney R-1830-49 or R-1830-57, generating 1,200 hp.
• Induction System: The defining engineering achievement of the P-43 was its integrated General Electric B-2 turbo-supercharger nestled deep within the belly/tail spine. Long exhaust trunks routed gases back to drive the turbine, allowing the engine to maintain its full 1,200 hp output well past 20,000 feet.

Handling & Stability Studies

• Directional Instability: Early YP-43 flight evaluations revealed a severe tendency to violently yaw and ground-loop during high-speed landing and takeoff rolls. Engineering bulletins corrected this by widening and redesigning the tailwheel tracking assembly.
• High-Altitude Stability: Thanks to its stable, broad-chord wing profile, the P-43 exhibited clean longitudinal stability in thin air. However, because weight escalated faster than control surface area, lateral responsiveness (roll rate) deteriorated sharply at lower speeds compared to the nimble P-35.
• Spin Characteristics: The deep "razorback" fuselage spine on the P-43 provided excellent directional tracking in high-speed dives, but it could partially shield the rudder during extreme high-alpha spins, necessitating careful recovery technique.

Performance Data

Engineering Bulletins & Modifications

• Wet-Wing Integrity: Bulletins from operations in China detailed critical failures of the P-43's unarmored "wet wing" integral fuel tanks. Lacking self-sealing bladders, they leaked persistently under combat vibrations, requiring extensive field sealing retrofits.
• Cooling Deficiencies: The tightly baffled ovoid cowling frequently caused rear-cylinder overheating during high-power climbs. Engineering bulletins dictated a precise step-by-step cowl flap management checklist for pilots to avoid terminal engine seizure.
• Reconnaissance Conversions: As performance became obsolete for frontline European air combat, engineering orders shifted late-production airframes to RP-43, P-43B, and P-43C configurations. These bulletins detailed the removal of heavy fuselage weaponry to install a specialized multi-camera mapping suite in the belly.

Surviving Examples & Historical Cost

• Flyable Survivors: No true single-seat Seversky P-35s or Republic P-43 Lancers currently fly. The only airworthy Seversky in the world is a two-seat trainer variant of the P-35 — the AT-12 Guardsman — making this lineage extraordinarily rare in the warbird community.
• Museum Survivors: Only one intact P-35 survives in a museum collection. Its current value is inestimable given its singular status.
• Original Procurement Cost: The USAAC ordered the Seversky P-35 at approximately $22,000–$30,000 per unit in the late 1930s — a figure that underscores how completely these aircraft have vanished from the market and why primary-source engineering documentation of this lineage is so exceptionally scarce.

Why This Collection Matters

This is one of the rarest and most sought-after collections of American WWII-era fighter documentation. The P-43 Lancer and Seversky P-35 represent the "missing link" in American fighter evolution—the bridge between pre-war designs and the dominant fighters of WWII. With only 272 P-43s and 76 P-35s produced, original documentation is exceptionally scarce. This archive preserves the complete engineering heritage of these historically significant aircraft.

Download Instructions

This collection is delivered as a single RAR archive file for digital download:

1. After purchase, you will receive an email with a download link to the RAR file
2. Download the RAR file to your computer
3. Use WinRAR, 7-Zip, or similar extraction software to extract the archive
4. The complete collection will be extracted, containing the index and all engineering drawings in TIFF and PDF formats
5. File is large — ensure you have adequate storage space and a stable internet connection

Legal Notice

This documentation is provided by Online Aviation Library, operated by Sicuro Publishing, under a structured licensing framework. Sicuro Publishing does not distribute controlled content—we provide documentation structuring, compliance architecture, and publishing systems for content legally owned by our clients and licensing partners.

These materials are sold for historical reference, research, and archival purposes only. The Republic P-43 Lancer and Seversky P-35 are no longer in active production. This collection serves historians, museum professionals, restoration specialists, aerospace engineers, scale modelers, and researchers requiring primary source technical documentation.

Your purchase grants permanent ownership of this structured collection with free lifetime updates. This is exclusive documentation not widely available elsewhere.

The compilation, structure, indexing, and presentation are © Sicuro Publishing, registered in the Canadian Copyright Database. Underlying historical factory materials remain the property of their original creators or successor entities.

These drawings are not meant to be used for current certification or repair work. Information is for reference only, and we do not guarantee completeness, accuracy, or currency of any drawings. This set is extensive but not exhaustive of every drawing ever produced for these aircraft.

Reference to commercial products, trade names, or manufacturers does not imply endorsement or affiliation. All trademarks are the property of their respective owners.

This is an archival, static-copy edition fixed at its original publication date. Intended for historical reference, flight simulation, museum restoration, and educational use only. Not approved for active airworthiness maintenance under FAA 14 CFR § 43.13, EASA Part-M, or equivalent international regulations. Operators of active aircraft must use current, revision-controlled publications from the Type Certificate holder or an authorized distributor.
Living Collections with Free Lifetime Updates — Please review our Disclaimer and Export Notice before purchasing.