Porsche PFM 3200
The Porsche PFM 3200 was a 6- cylinder aircraft engine for light aircraft of the German sports car manufacturer Porsche. Aircraft manufacturers Robin, Mooney and Cessna were equipped with this engine.
- 2.1 Structure
- 2.2 cooling
- 2.3 Mixture preparation
- 2.4 ignition
- 2.5 propeller governor
- 2.6 Advantages of interpretation
- 3.1 circumnavigation
- 3.2 Spare engines
- 3.3 OE
History
Development
The Mindelheimer contractor and aircraft maker Burkhart Grob gave in 1977 the impetus for the development of modern piston engines for the then emerging developments in general aviation aircraft. To this end, his company Burkhart Grob Aerospace modified a tentative engine of the Porsche 911 Turbo with dual ignition and gear reducer.
As of May 1981 began at Porsche in Weissach, the first study work for a built-in motor and as of October 1981, the development of the PFM 3200, was supposed to replace the technically outdated engines from Lycoming and Continental Motors American design, the construction of which dates back nearly unchanged to the 1940s and 1950s.
"Without the dedication and infectious enthusiasm of Mr. coarse it would hardly come so far. "
Flight testing and approval
As of August 8, 1982, a Cessna flew 182 Skylane, the original engine was replaced with a Continental O -470 by a PFM 3200, with the registration D - EIMP at the airfield Mindelheim - Mattsies - the factory airfield of the company Burkhart Grob Aerospace - 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 took place in 1984, the need for the U.S. market FAA certification to FAR Part 33 followed in 1985. Starting in April 1987, the engine went into series production.
Cessation of production
Despite technical advantages of the PFM 3200 was not accepted by the market, as in the U.S., the market for aircraft virtually came the mid-1980s because of a judgment on product liability to a halt. An upgrading of used aircraft was unattractive given the low fuel costs in the U.S..
"The reason was a spectacular and all the conflicting forecasts drop in global sales of small aircraft, which made the project uneconomic. "
The series production of the engines ended in 1990.
After cessation of production of the PFM caused 3200 for Porsche high costs in the tens of millions annually, as in the U.S., securing a long-term maintenance and spare part availability is either imposed by law. Therefore, the Group 2005, still existing residual stocks of Porsche engines decided to draw sponsored by conversion to other engines or, if necessary, by buying up entire aircraft from the traffic.
Construction
The PFM 3200 was derived structurally from the previously over 200,000 built air-cooled boxer engine with six cylinders of the 911 sports car. The crankshaft with a stroke of 74.4 millimeters corresponded to the design of the engine of the 911 Turbo 3.3 since 1977, with the bore 95 millimeters was offered in combination with this crankshaft in automobile until 1984 in 911 Carrera 3.2. A stated goal was to make available to the motor vehicle constructive developments of the aircraft engine - and vice versa.
Construction
The six individual cylinder heads and cylinders were screwed to studs with vertically split crankcase. About three cylinder heads, a camshaft housing was disposed on the above of a camshaft and rocker arm, the V -shape are pressed in the cylinder head hanging valves.
A cascade gear on the back of the motor drive to the camshaft from the crankshaft - in contrast to the chain drive in the vehicle engine at this point. The wheels could serve as additional housing for driving two alternators, two suction pumps for air, two Hochspannungszündverteiler and a propeller governor.
Before starting the engine, the propeller gearbox was arranged, which reduced the engine speed in the ratio 1:0,442 on the propeller speed. The helical gearing of the Getriebräder relieved the thrust of the propeller shaft. For mutual absorbs vibrations from a rubber joint disc with textile insert loop on the transmission input shaft was arranged. With this coupling the crankshaft should be protected in the event of contact with the ground of the propeller - the so-called "shock loading". An addition to install intermediate gearbox was also able to reverse the normally left-handed propeller rotation - essential for two-engine airplanes. In addition to the propeller reduction gear, the starter had its place.
The sophisticated dry sump lubrication worked with an external oil tank, which was prepared for an automatic oil level control and allowed conceptually the full aerobatic capability of the drive. Even the propeller reduction gear and the propeller governor ran with engine oil.
Cooling
For forced cooling of the engine drove two parallel belts to a running 1.7 -fold speed axial fan. In contrast to the usual ram air cooling at comparable aircraft engines, the critical field of high power delivery with simultaneously low speed of the aircraft was optimal by the highest air flow rate at maximum engine speed of 5300 min-1 covered.
Mixture preparation
The injection of the fuel carried by an adapted K -Jetronic from Bosch, who came again on PFM 3200 in the purely mechanical basic version for use - as opposed for use in vehicle engines, which in the 1980s already with subsequent generations KA or KE- Jetronic were equips.
A feature were two control pressure regulator of the fuel injection, which are driven as a function of the throttle lever position. A control pressure regulator was in all operating conditions for the observance of the operating state " effective consumption (best economy) " with a combustion air ratio of 1.10 in charge, a further control pressure regulator was activated by a solenoid valve at full load and resulted in a richer mixture in a combustion air ratio of 0.85 for the operating state "Maximum Performance (best power) " - this enrichment was only briefly active as a rule, during takeoff and climb up to the minimum safe altitude.
Ignition
The engine had two independent electronic map- Ignition Magneti Marelli, consisting of a generator, harness, control unit, TDC sensor, speed sensor, temperature sensor in the intake manifold, intake manifold pressure sensor, ignition coil, high voltage distribution, ignition harness and six spark plugs with shielded spark plugs per ignition circuit. The cylinder heads have correspondingly - in contrast to the vehicle engine - two spark plugs. In vehicle the dual ignition followed only in 1988 in the Porsche 964 series.
The PFM 3200 differed sharply from comparable aircraft engines, which are equipped today with magneto ignition and therefore much easier to achieve the required reliability and redundancy.
Propeller governor
The propeller governor was operated by the " throttle " and was an integral part of the " single lever ".
The throttle worked first on the throttle, which was fully open when " power - giving" even at an engine speed of 2300 min-1. A further increase in speed prevented at this operating point - of about 40 % of the starting power equivalent - the propeller governor that controlled the pitch of the propeller according to keep the speed. More " power - Type " caused only an increase in the speed setting of the propeller governor to an engine speed of 5000 min -1. At " full power " enriched the mixture by the activation of the second control pressure to control the propeller governor and the engine speed is governed at 5300 min -1 - so that the starting power was achieved. This operating point was additionally indicated by an indicator light.
Benefits of interpretation
The concept offered basic advantages over almost all standard engines on the market at the beginning of the 1980s:
- Low sound emissions
- Higher efficiency, lower fuel consumption
- Depending on the design operating with a favorable Mogas instead of the expensive AvGas
- Compared with other aircraft engines very simple operation using the single lever for gas, propeller and mixture adjustment
The competitors tried to point out the disadvantages of the electronic ignition system instead of the magneto ignition used by them in public. Porsche's ignition system was dependent on at least one functioning generator, fell from both generators could be flown for about an hour on battery power. The conventional magneto ignition works fine even without external power supply. This point was one of the reasons for the commercial failure success.
Use
Circumnavigation of the world
The reliability of the engine Porsche demonstrated in 1985 with a flight around the world with a single-engine Mooney M20J 201 with the registration D - EAFE. The pilots were Michael Schultz and Hans Kampik. The flight began on 10 July 1985 at the airfield Donaueschingen -Villingen and ended on 16 January 1986 back to Donaueschingen - after about 100,000 km in 600 hours of flight time, 300 takeoffs and landings, a fuel consumption of 23,000 liters and an oil consumption of 30 liters. The longest flight was about 17 hours with the 3700 km long section of Majuro in the Marshall Islands to Honolulu in Hawaii, the longest non-stop flight was 3900 km from Hawaii to California.
Spare engines
The cost of converting a standard Cessna 172 were estimated by experts in 1987 to 80,000 to 90,000 DM - 2.5 times a comparable conversion with an engine from Continental and Lycoming. Due to the expected fuel savings, the investment would thus other hand, pays for itself in no more than 1200 hours of operation.
Original
- Built in Motor Type N03, about 40: Mooney M20L PFM
- Robin DR 400/RP: silent towplane
- Socata TB 15 and TB 16: planned, not running