Porsche 645
| Porsche | |
|---|---|
| Image does not exist | |
| 645 Spyder | |
| Presentation year: | 1956 |
| Vehicle fair: | |
| Class : | Sports car |
| Body shape : | Roadster |
| Engine: |
Otto engine : 1.5 liters (85 kW) |
| Length: | 3775 mm |
| Width: | 1420 mm |
| Height: | 900 mm |
| Wheelbase: | 2000 mm |
| Empty weight: | 550 kg |
| Production model: | none |
The Porsche 645 Spyder was a racing sports car prototype from Dr.-Ing. hc F. Porsche KG . It was planned as the successor to the Porsche 550 . However, development of the car was discontinued in favor of the Porsche 718 before completion .
development
The development of the Porsche Type 645 began at the end of 1954. The goal was a lighter racing car than the Porsche 550. It should also offer better aerodynamics and more static friction .
The project was started by Egon Forstner, the head of the Porsche calculation department. He was supported by Ernst Fuhrmann , the designer of the 547 engine, and by the car and body designer Heinrich Klie. Starting with the 550, Klie made a 1: 5 scale model to experiment with several new body features. This included a headrest that was aerodynamically integrated into the body and a gap that was open to the rear, in which the air swirled by turbulence for the engine cooling could get better into the engine compartment. Klie and Fuhrmann were granted patents for the two new developments.
On February 15, 1955, in the middle of the development of the 645, Porsche chief engineer Karl Rabe asked management to review the project, as it needed more human support and more money. The project was then stopped, especially since the 550 racing cars used proved to be competitive and no new car was needed. Only when Porsche was expecting competition with the newly redesigned Borgward RS that had been announced , the project was restarted on February 16, 1956. In the work instruction no. 9159 issued for this purpose, the construction of two prototypes was commissioned.
The first prototype was completed for testing in mid-June 1956. Herbert Linge tested the vehicle near Malmsheim . It turned out that the car was faster, but hardly predictable in its driving behavior and more difficult to control than the 550.
Porsche entered the 645, driven by Richard von Frankenberg , in a few races. On September 16, 1956, von Frankenberg had an accident with the car while racing on the AVUS . Frankenberg was thrown out of the car; he survived the accident with minor injuries. The only completed prototype burned out completely. The project was then discontinued.
Much of the knowledge gained during development was incorporated into the Porsche 718 , which was later produced , and successfully implemented there.
Vehicle characteristics
body
The Porsche 645, developed in 1954, already had a tubular space frame , as it was later used in the Porsche 550 A in 1956. In order to achieve the lowest possible vehicle weight, the outer shell of the body was made from the lighter magnesium instead of aluminum . At the same time, the car became smaller than the 550, so that the wheelbase was shortened by 100 mm to 2000 mm.
In order to reduce the frontal area and thus the aerodynamic drag of the racing car in order to increase the top speed, the developers reduced the front track to 1190 mm and rear to 1150 mm. Because of its small size and especially because of its unpredictable driving behavior, Richard von Frankenberg later called the car Mickey Mouse.
The front was pulled lower and already resembled that of the later Porsche 718 . The rear was redesigned and had two rear-facing openings on the left and right for the engine air intake and a gap that was also open to the rear for the engine cooling. To accommodate the fan for the engine cooling, the rear had a bulge in the middle.
The capacity of the petrol tank placed in the front was reduced from 130 to 80 liters so that it could fit into the small body. To compensate for this, Porsche installed a tank with a capacity of around 40 to 50 liters to the right of the driver in the driver's cab. As a result, the right door was omitted on the 645.
landing gear
The car had independent wheel suspension at the front and rear and a crank-arm axle at the front . The rear suspension was designed differently than on the 550 and was similar to that of the earlier Porsche racing car project Cisitalia 360. It had trailing arms and upper and lower wishbones connected to torsion springs. The wishbones were swept back slightly. The lower link ran parallel to the ground, while the upper link pointed slightly downwards.
Like the 550, the prototype had drum brakes all around . The 16-inch wheels had 5.00-16-RS tires at the front and 5.25-16-RS tires at the rear.
engine and gears
The vehicle was powered by an early version of the so-called Fuhrmann engine type 547, as the newer version required more space that was not available in the small engine compartment of the 645.
This air-cooled 1.5-liter four-cylinder boxer engine developed around 15 kW (20 hp) less than the more modern version of the 547, which delivered 99 kW (135 hp) at 7200 rpm, and also had two camshafts on each side , which were driven by vertical shafts.
The engine had double ignition with two separate ignition distributors and two ignition coils. Two Weber double falling flow carburettors of the type 40 DCM were used for the mixture preparation . The maximum torque was 145 Nm at 5900 rpm.
The fully synchronized four-speed manual transmission was taken from the Porsche 550 and was also placed behind the rear axle.
Racing history
The prototype took part in its first test runs on a racetrack on May 15 and 16, 1956 at the Nürburgring . The car was driven by Wolfgang von Trips , who achieved a lap time of under eleven minutes. At the same time, Hans Herrmann drove a 550 A and undercut the time of the 645 with 10: 35.2 minutes. After Herrmann had also tested the 645, he came to the conclusion that the car was faster, but "absolutely undrivable".
On May 27 of the same year Richard von Frankenberg tested the prototype during training for the 1000 km race on the Nürburgring . In the actual race, he and Hans Hermann decided not to use it in favor of the Porsche 550 A, with which both achieved sixth place in the overall standings.
The 645 first raced on July 22, 1956 at the Solitude race. Von Frankenberg, starting from second place, struggled with technical problems during the race. Despite the loss of first gear, brake problems, loss of power and excessively high oil temperatures, he finished fourth.
The second and final race of the prototype took place on September 16, 1956 at the Berlin Grand Prix, the sixth race of the German Sports Car Championship, at the AVUS. Von Frankenberg decided to drive the race with the so-called Mickey Mouse because the car reached a higher top speed than the 550 and the racetrack with its long straights and few corners was designed for high speeds.
Starting from third place with starting number 9, von Frankenberg took the lead, followed by Wolfgang von Trips with a 550 A. In the third lap the 645 suddenly turned right and flew over the edge of the 43 ° - North curve. The car crashed into the paddock about 15 meters below, where it immediately caught fire and burned out completely, including the magnesium body. About five minutes after the accident, a Porsche technician found the unconscious Richard von Frankenberg, who was thrown out of the car over the banked curve as he took off. Von Frankenberg was almost unharmed. He stayed in the hospital for five weeks before he was released and continued racing. Because of the happy outcome for von Frankenberg, the accident was later referred to as the AVUS miracle.
After this event, no further 645s were set up and the project ended.
The information gained from the prototype about the advantages of an aerodynamically designed body and an advanced wheel suspension in a racing car had a significant influence on the development of the later Porsche 718.
Technical specifications
| Porsche 645 Spyder: | Data |
|---|---|
| Engine: | 4-cylinder boxer engine (four-stroke) (type 547) |
| Displacement: | 1498 cc |
| Bore × stroke: | 85 × 66 mm |
| power | 85 kW (115 PS) at 7200 rpm |
| Max. Torque : | 145 Nm at 5900 rpm |
| Compression: | 9.8: 1 |
| Valve control: | two overhead camshafts, driven by vertical shafts |
| Cooling: | Air cooling (vertical fan) |
| Transmission: | 4-speed gearbox |
| Brakes: | Drum brakes |
| Front suspension: | Crank trailing arm |
| Rear suspension: | asymmetrical wishbones |
| Front suspension: | Torsion bar springs |
| Rear suspension: | 1 round torsion bar on each side |
| Body: | Tubular space frame |
| Track width front / rear: | 1190/1150 mm |
| Wheelbase : | 2000 mm |
| Tires: | 5.00-16 RS / 5.25-16 RS; 5.50-16 |
| Dimensions L × W × H: | 3775 × 1420 × 900 mm |
| Empty weight : | 550 kg |
| Top speed: | 260 km / h |
literature
- Karl Ludvigsen: Classic Porsche No. 57: Mickey Mouse. CHPublications Ltd, Bletchingley (UK) September 27 to November 14, 2018, ISSN 2042-1079 . ( PDF; 29 MB), here pp. 54–60.
- Jürgen Barth, Gustav Büsing: The big book of the Porsche types. Race car. Motorbuch Verlag, Stuttgart 2010, ISBN 978-3-613-03241-5 .
Individual evidence
- ↑ a b c d Karl Ludvigsen: Classic Porsche No. 57: Mickey Mouse. P. 55.
- ↑ a b c d Karl Ludvigsen: Classic Porsche No. 57: Mickey Mouse. P. 57.
- ↑ a b c d Karl Ludvigsen: Classic Porsche No. 57: Mickey Mouse. P. 58.
- ^ A b c Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 31.
- ↑ a b c d e Karl Ludvigsen: Classic Porsche No. 57: Mickey Mouse. P. 59.
- ^ A b c Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 13.
- ↑ a b c d e Karl Ludvigsen: Classic Porsche No. 57: Mickey Mouse. P. 60.
- ↑ a b c d Karl Ludvigsen: Classic Porsche No. 57: Mickey Mouse. P.56.
- ↑ a b Mickey Mouse. In: Type550.com. Retrieved July 20, 2019 .
- ↑ Jürgen Barth, Gustav Büsing: The great book of the Porsche types. Race car. P. 12.
- ^ A b c Tim Havermans: Richard von Frankenberg survives horrible crash at the Avus Ring in Berlin. In: LoveForPorsche.com. September 16, 2016, accessed July 20, 2019 .