P-35A Replica

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HISTORY

The Seversky/Republic P-35 was first delivered in 1937 and is recognized as the U.S. Army Air Corps first modern fighter aircraft. It was the first all-metal, single seat, low-wing monoplane design, with full instrumentation, an enclosed cockpit, and retractable landing gear. These key design attributes are still the basis for contemporary fighter jets. This design would gradually grow and evolve into the P-47 "Thunderbolt".

 The P-35 was regarded as far superior to most other aircraft by pilots of its time. Only two versions were built, with 77 P-35's and 60 P-35A's in total being produced. The P-35A was a design improvement of the P-35 and was intended for shipment to Sweden before a war embargo diverted most aircraft into US service. They served in the early part of World War II in the Philippines. Unfortunately most aircraft were damaged or lost. Only a small number of P-35's left stateside for training and P-35A's that had been purchased by Sweden made it through WWII. As a result only one P-35 and two P-35A's survive today. 

SELECTION

 In searching for a project to undertake, many designs were evaluated by VCS. The P-35A was selected due to its unique background. Copies of factory blueprints were available and surviving examples exist to study. Additionally "off the shelf" adaptable items such as engines, propellers, wheels, are readily available for purchase in quantity.

Modern materials and technology should create a better and more reliable product than what was first produced in 1935.  VCS hopes to maintain design accuracy (within the margin of safety as most Warbird replica/restorations strive to maintain). Changes will have to be made in the power plant to incorporate an available engine and propeller. 

CHANGES/UPDATES

1. The replica is to be powered by a R-1830-92 Pratt and Whitney power plant as fitted to the C-47/DC-3. The aircraft was originally powered by (P-35) R-1830-9 and (P-35A) R-1830-45 that are nonexistent. For mock up and preliminary fitting FWF (firewall forward) as many C-47 or PBY parts will be used as possible (engine mount, accessory cowling). To this end a core R-1830-92 rear accessory case and C-47 upper accessory cowling have been found and purchased. 

2. The replica will have the Hamilton Standard 3E50 counterweight propeller replaced with the HS 23E50 hydromatic propeller. As (again) the counterweight propeller is nonexistent and the 23E50 is very available. A non feathering 23E50 hub similar to what is fitted to the new build Yak-3 was purchased.

3. This replica will be a full scale, all aluminum flyable replica of the Seversky/Republic P-35A. To enable remanufacture, an effort is under way to completely "Loft" the aircraft with specialized software. This will define the true and accurate airframe design from which all parts will be built around. All jigs, fixtures will be designed and parts will be redrawn with 3D CAD software and checked for fit and structural integrity. This process mirrors the development and engineering of current aircraft design.  An amazing potential exists of what can be accomplished with state of the art manufacturing methods (CAM , rapid prototyping ect.) for this project.
 

(P-35A Engine Cowl)                                                                    (AT-12 Engine Cowl & 23E50 Prop)

   

               (C-47 Engine Cowl & 23E50 Prop)                                    (PBY Engine Cowl & 23E50 Prop)


 MARKINGS

VCS as chosen to honor the 5th Air Force, 24th Pursuit Group, 17th Squadron that "drew first blood" in December 1941. The first aircraft will be painted in representative colors of an aircraft from that group. Historical pictures have been consulted and a rendering commissioned based upon them.

 

 

2D CAD & CNC Technology

To validate the design and manufacturing process, several small "proof of concept" projects have been undertaken by VCS.  A set of new P-35A instrument panels were modeled from factory blueprints, drawn in 2D CAD, and then cut out by a CNC mill. The firewall was also redrawn in 2D CAD and the shape was cut out of MDF with a gantry CNC router. The results are illustrated below:

                                     

3D CAD & Rapid Prototyping

To demonstrate the use of new technology in the building of the P-35A replica, the following example is shown. This is the rudder hinge bracket that is fitted to the vertical stabilizer. This part is unique in that it also fits the P-47 Thunderbolt. No original examples were able to be procured. New parts had to be fabricated from original drawings. Shown is the original print, the 3D CAD design and the new part that was produced using 3D rapid prototyping.

                                          

 

 FULL SCALE MOCK UP

To further validate blueprint to part manufacture, the aft section of the aircraft was constructed out of MDF. The vertical stabilizer is presently being constructed. Pictures will be posted as progress continues.

(Replica Jig, Aft Fuselage and Vertical Stabilizer Under Construction)

  

(Original AT-12/P-35A Aft Fuselage and Vertical Stabilizer)

 

  


 

 

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Last modified: 11/29/09