Porsche PFM 3200
| Porsche | |
|---|---|
 Porsche PFM 3200 |
|
| Porsche PFM 3200 | |
| Production period: | 1984-1990 |
| Manufacturer: | Porsche |
| Working principle: | Otto |
| Motor design: | Six - cylinder boxer engine |
| Displacement: | 3164 cm 3 |
| Mixture preparation: | Manifold injection |
| Engine charging: | no |
| Power: | 147 kW |
| Dimensions: | 200 kg |
| Previous model: | none |
| Successor: | none |
The Porsche PFM 3200 was a 6-cylinder aircraft engine for light aircraft made by the German sports car manufacturer Porsche . Aircraft from the manufacturers Robin , Mooney and Cessna were equipped with this engine.
history
development
The Mindelheim entrepreneur and aircraft manufacturer Burkhart Grob gave the impetus to develop modern piston engines for the then newly emerging aircraft developments in general aviation. For this purpose, his company Burkhart Grob Luft- und Raumfahrt modified an engine of the Porsche 911 Turbo with dual ignition and reduction gear on a trial basis .
The first study work for a built-in engine began at Porsche in Weissach in May 1981 and, from October 1981, the development of the PFM 3200 , which was to replace the technically outdated American-made engines from Lycoming and Continental Motors , the design of which goes back almost unchanged to the 1940s and 1950s .
"Without Mr. Grob's commitment and infectious enthusiasm, it would hardly have come to this."
Flight testing and approval
From August 8, 1982, a Cessna 182 Skylane , whose original engine had been replaced with a Continental O-470 by a PFM 3200 , with the registration D-EIMP at Mindelheim-Mattsies airfield - the works airfield of the company Burkhart Grob Luft- und Raumfahrt - the flight program for the approval of the new engine. The drive was equipped with a Hoffmann three-blade propeller.
The German approval according to the European JAR-E followed in 1984, the FAA approval according to FAR Part 33 necessary for the American market followed in 1985. From April 1987 the engine went into series production.
Cessation of production
Despite its technical advantages, the PFM 3200 was unable to establish itself on the market because the aircraft market in the USA practically came to a standstill in the mid-1980s due to a ruling on product liability . Converting used aircraft was unattractive given the low fuel costs in the US.
"The reason was a spectacular and all forecasts contradicting decline in global sales of small aircraft, which made the project uneconomical."
Series production of the engines ended in 1990.
After production was discontinued, the PFM 3200 caused high costs in the double-digit million range for Porsche every year, as long-term maintenance and spare parts availability are sometimes required by law in the USA. That is why the group decided in 2005 to withdraw the remaining stocks of Porsche engines by sponsoring them to convert them to other engines or, if necessary, by buying up entire aircraft.
construction
The construction of the PFM 3200 was derived from the air-cooled boxer engines with six cylinders of the 911 sports cars , which had been built up to then over 200,000 . The crankshaft with a stroke of 74.4 millimeters corresponded to the design of the engine of the 911 Turbo 3.3 since 1977, the 95 millimeter bore was only offered in combination with this crankshaft in vehicle construction from 1984 in the 911 Carrera 3.2 . The declared aim was to allow the vehicle engine to develop structural developments for the aircraft engine - and vice versa.
construction
The six individual cylinder heads and cylinders were bolted to the vertically divided engine housing using stud bolts. A camshaft housing was arranged above three cylinder heads, from which the V-shaped hanging valves in the cylinder head were operated via a camshaft and rocker arm.
A gear cascade on the rear of the engine drove the camshafts from the crankshaft - in contrast to the chain drive in vehicle engines at this point. The wheel housing could also serve to drive two three-phase generators, two suction pumps for air, two high-voltage ignition distributors and a propeller regulator.
The propeller gearbox was located in front of the engine and reduced the engine speed to the propeller speed in a ratio of 1: 0.442. The helical teeth of the gear wheels relieved the thrust bearings of the propeller shaft. A rubber swivel washer with a textile loop insert was arranged on the transmission input shaft for mutual vibration decoupling. This coupling should also protect the crankshaft in the event of the propeller touching the ground - the so-called "shock loading". With an additional idler gear, the gearbox was also able to reverse the direction of rotation of the propeller, which is normally counterclockwise, which is essential for twin-engine aircraft. The starter had its place next to the propeller gear.
The complex dry sump lubrication worked with an external oil tank that was prepared for an automatic oil level check and conceptually enabled the drive to be fully aerobatic. The propeller gearbox and the propeller regulator also ran on engine oil.
cooling
For forced cooling of the motor, two parallel V-belts drove an axial fan running at 1.7 times the speed. In contrast to the otherwise common ram air cooling in comparable aircraft engines, the critical range of high take-off power with simultaneously low aircraft speed was optimally covered by the highest air throughput at a maximum engine speed of 5300 min −1 .
Mixture preparation
The fuel was injected by an adapted K-Jetronic from Bosch , which was used again in the purely mechanical basic version on the PFM 3200 - in contrast to the use in vehicle engines, which were already used in the 1980s with the successor generations KA and KE. Jetronic equip.
A special feature were the two control pressure regulators of the injection system, which were activated depending on the throttle position. A control pressure regulator was responsible in all operating states for maintaining the operating state "best economy" with a combustion air ratio of 1.10, another control pressure regulator was activated by a solenoid valve at full load and produced a richer mixture with a combustion air ratio of 0.85 for the operating state "maximum power (best power)" - this enrichment was usually only active for a short time during takeoff and climb up to the minimum safety altitude.
ignition
The engine had two independent, electronic mapped ignition systems from Magneti Marelli , consisting of a generator, wiring harness, control unit, TDC sensor, speed sensor, temperature sensor in the intake manifold, intake manifold pressure sensor, ignition coil, high-voltage distributor, ignition harness and six spark plugs with shielded spark plug connectors per ignition circuit. The cylinder heads accordingly - in contrast to the vehicle engines - each had two spark plugs. In vehicle construction, double ignition did not become standard in the Porsche 964 until 1988 .
The PFM 3200 differed significantly from comparable aircraft engines, which are still equipped with magneto ignition and can thus achieve the required operational reliability and redundancy much more easily.
Propeller regulator
The propeller regulator was operated by the "throttle lever" and was an essential part of the "single lever operation".
The throttle first acted on the throttle valve, which was fully opened when the engine was “giving power” at an engine speed of 2300 min −1 . A further increase in speed was prevented at this operating point - which corresponded to about 40% of the take-off power - the propeller regulator, which controlled the pitch of the propeller accordingly in order to maintain the speed. Further "power output" only resulted in an increase in the speed setpoint of the propeller governor up to an engine speed of 5000 min −1 . At "full power", the mixture was enriched by activating the second control pressure regulator and the propeller regulator regulated the engine speed to 5300 min −1 - the take-off power was thus achieved. This operating point was also indicated by a control lamp.
Advantages of the design
The concept offered fundamental advantages over almost all standard engines on the market in the early 1980s:
- low noise emissions
- higher efficiency, lower fuel consumption
- Depending on the version, operation with inexpensive MoGas instead of expensive AvGas
- Compared to other aircraft engines, it is very easy to operate thanks to the single-lever operation for gas, propeller adjustment and mixture regulation
Competitors did their best to publicly point out the disadvantages of the electronic ignition system in place of the magneto ignition they used. Porsche's ignition system was dependent on at least one functioning generator; if both generators failed, the flight could continue for about an hour on battery power. Conventional magneto ignition, on the other hand, also works without an external power supply. This point was one of the reasons for the commercial failure.
use
Circumnavigation
Porsche demonstrated the reliability of the engine as early as 1985 with a flight around the world in a single-engine Mooney M20J 201 with registration D-EAFE . The pilots were Michael Schultz and Hans Kampik. The flight began on July 10, 1985 at Donaueschingen-Villingen airfield and ended again in Donaueschingen on January 16, 1986 - after about 100,000 kilometers in 600 flight hours, 300 take-offs and landings, a fuel consumption of 23,000 liters and an oil consumption of 30 liters. The longest flight was the 3700-kilometer section from Majuro on the Marshall Islands to Honolulu in Hawaii at 17 hours , the longest non-stop flight was 3900 kilometers from Hawaii to California .
Replacement engines
The cost of converting a standard Cessna 172 was estimated by experts in 1987 at 80,000 to 90,000 DM - 2.5 times as much as a comparable conversion with an engine from Continental or Lycoming. On the other hand, due to the expected fuel savings, the investment would have paid for itself after a maximum of 1200 operating hours.
Original equipment
- Mooney M20L PFM : engine type N03, built around 40
- Robin DR 400 / RP : low-noise tow plane
- Socata TB 15 and TB 16 : planned, not executed
- Akaflieg München Mü 30 : planned, change to Lycoming AEIO-540-L1B5D
Technical specifications
| Parameters | Data of the PFM 3200 |
|---|---|
| Manufacturer | Porsche |
| Construction year | 1984 |
| design type | 6-cylinder boxer engine, two valves per cylinder, one overhead camshaft per cylinder bank |
| Displacement (bore × stroke) | 3164 cm³ (95 mm × 74.4 mm) |
| compression | 9.2: 1 |
| Dry matter | approx. 200 kg |
| Starting power | 156 kW (212 hp) at 5300 min -1 |
| Travel service | 147 kW (200 hp) at 5000 min -1 |
See also
literature
- Robin Blech, Janice Lowe: Porsche: the warm-up lap is over. In: Flight International. April 4, 1987, ISSN 0015-3710 , pp. 21-23 ( flightglobal.com PDF).
- Jürgen Gassebner: "Porsche Aviation - More than 100 years of Porsche aircraft engines", 2020, ISBN 978-3-00-066185-3 https://www.porsche-aviation-book.com/
Web links
- Engine data sheet No. 4602. (PDF) In: Equipment data sheet (§4 LuftVZO). Luftfahrt-Bundesamt, January 30, 1989, accessed on November 30, 2014 (data sheet for the PFM 3200 N).
- Engine data sheet No. 4609. (PDF) In: Equipment data sheet (§4 LuftVZO). Luftfahrt-Bundesamt, December 23, 1988, accessed on November 30, 2014 (data sheet for the PFM 3200 T).
Individual evidence
- ↑ a b c d Porsche learns to fly . In: Fliegermagazin . No. 11 . Jahr Verlag GmbH, November 1983, ISSN 0170-5504 , p. 26–27 ( fliegermagazin.de [PDF; accessed November 30, 2014]).
- ↑ a b Flying leg. Spiegel Online , April 1, 1985, accessed November 8, 2012 .
- ↑ Porsche-powered Cessna flies. Flight International , October 8, 1983, p. 947 , accessed on November 30, 2014 (English): “The Skylane flight-test program has been running since August 9, at Mindelheim-Mattsies, where glider and motorglider manufacturer Grob Flugzeugbau is based . The two companies are said to be working together closely, Grob having encouraged the Porsche management to enter the aero-engine market. "
- ↑ a b c Robin Blech: Porsche: the warm-up lap is over. Flight International , April 4, 1987, pp. 21-24 , accessed October 30, 2012 .
- ↑ Jochen Pade: A two-stroke for the air. Die Zeit, October 2, 1992, accessed on March 14, 2016 : “Example Porsche: In 1980 the company began developing a new gasoline aircraft engine; Approval was granted in 1985 and production stopped in 1990. "
- ↑ a b losses at Porsche. Spiegel Online , March 7, 2005, accessed on November 30, 2014 : “ So Wiedeking was not sad about a report from the USA: Several aircraft with Porsche engines were destroyed by a hurricane, and nobody was harmed because the machines stood on the ground. "
- ↑ a b Takers for Porsche aircraft engine? Flight International , December 25, 1986, p. 13 , accessed November 1, 2012 .
- ↑ a b c d Heinz Dorsch, August Hofbauer and Hans Weiner: The Porsche PFM 3200 aircraft engine . In: Motortechnische Zeitschrift . tape 46 , no. 7/8 . Springer Vieweg Verlag, 1985, p. 275-281 .
- ↑ Porsche power tours the world. Flight International , August 17, 1985, p. 12 , accessed November 30, 2014 .