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The Engine |
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I decided to investigate the alternative to a Rotax 912. In Spring 1999
we visited the NSI Company in Arlington, WA. After getting an eye full of
their manufacturing facilities, I decided to purchase the
EA81-120-TBI including an electrically adjustable 3 bladed prop for 18'800$.
Unfortunately, the economy caught up with the NSI Company and they
changed hands. The new Company, MPS (Maxwell Propulsion Systems) is no
longer manufacturing the engine but does offer limited technical support. Here are some of the engine specs: |
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engine arrived completely assembled and ready to be mounted. In the
picture to the left, one can see the dual ignition going to one single spark plug
per cylinder. The air intake with the carburetor is on the left. |
Engine Type: EA81-120-TBI Serial Number: # 448807 Engine type: 4 stroke, automotive gas Ignition: single spark plug, dual ignition Power: approx. 110 HP Carburetor: ELLISON EFS-2 throttle bony, injector Cooling: Water + oil cooler Propeller: CAP 140 (3 blade, cockpit adjustable) Engine speeds: idle : 1500 RPM norm, 3500 RPM max 6000 RPM Propeller reduction gear: 1 : 2.8 |
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muffler with the pre-heater air intake is under the engine. The planetary
reduction gear reverses the propeller direction (counter clockwise seen
from the cockpit). The gear is equipped with a clutch to allow the
propeller to spin freely when the engine quits.
On the rear the V-belt driving the alternator and the water pump can be seen. This engine also has a direct take off shaft from the crankshaft where I attached a vacuum pump for some of the instruments. The tan colored tank on top is the oil reservoir which in principle, should assist the cooling of the oil. However, I found that an extra oil cooler was necessary, especially when climbing at higher altitudes. |
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picture to the left shows the engine mounted to the fire wall with the power and
some of the control cables passing through from the cockpit. Under the
engine is the water cooler and under the propeller reduction gear is the
oil cooler. As I had felt, the alternator was trapped in the back and could be
subject to higher temperatures, so I installed an air duct to direct ram air to
the alternator. Since this is a car engine requiring electrical power for
producing the spark, a healthy alternator is essential.The picture on the right shows the fuel line with the strainer and the rising line feeding the carburetor. In the picture - below right - the vacuum pump is visible. All the piping in the engine compartment is of race car quality. |
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The first fuel line installations proved to be inadequate as the automotive fuel had many additives which started to dissolve or disintegrate the hose and seals. Therefore I replaced most of the material with racecar quality material. |
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The propeller hub houses a geared electrical servo motor that adjusts the pitch of the propeller. The pitch can be run from +27 degrees to -27 degrees. The option of negative pitch was chosen to have the possibility of operating the Kitfox on floats. The gear shaft drives a potentiometer which sends a coded signal through the commutator rings to the cockpit control unit. |
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 Finally all the elements belonging to the engine were installed and could be tested! The next web pages will deal with the cockpit side of the engine and the avionics.
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Links to various Kitfox related sources:
NSI-Subaru Engine Interest groups: ....................................................
Maxwell Propulsion Systems, Inc.: successor of NSI ..................... 19132 59th Drive NE, Arlington, WA 98223 ph:(360) 474-8118
Kitfox Aircraft LLC ......................................................................................
Kitfox Mail Browser ....................................................................................
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http://groups.yahoo.com/group/airsoob/
http://www.maxwellpropulsion.com
http://www.kitfoxaircraft.com/
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For further information select from the directory at the top right Contact address is [email protected] This page was last maintained 2.9.2008 |
