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Help with a project

skygirl1968

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Greetings all! I'm working on a project for my systems class at school and I have a detailed question I need some help with. I need some help listing what kinds of instruments you would find in a piston powered aircraft (as opposed to a turbine) and how those instruments operate. Anything would hep, even just the name of instrument(s), I could look up how it operates from there. Any links, etc...thank you so much!!
:beer:
 

skygirl1968

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let me refine that...the instructor specified 'piston engine instruments & how they operate' someone else is doing turbine isntruments so i'm looking for instruments that would be specific to piston engines. thanks!!
 
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Balou

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Try to get a hold of an A&P powerplant and airframe text book. Jeppesen has one. Glenncoe text books are better. Some pilot shops have them. You could also try to ask a A&P at your local airport if you could borrow their copy if they still have them. Or you could find some info in the specific maintanance manual of a piston aircraft.

Is that picture from the Ballon fest in ABQ ?

Balou
 

skygirl1968

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the pic is from this years balloon fest.

is there anyone out there that knows off the top of thier head what engine instruments are specific to a piston engine??
 

Amish RakeFight

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is there anyone out there that knows off the top of thier head what engine instruments are specific to a piston engine??


Engine instruments commonly found on light pistons:

EGT (exhaust gas temperature)
CHT (cylinder head temperature)
MAP (Manifold absolute pressure gauge)
Tachometer (displays RPMs)
Prop synchronizer (twin)
Fuel pressure gauge
Oil pressure gauge
Oil temperature gauge
Ammeter (eletrical charge)
 

avbug

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Of those, only the manifold pressure guage is specific to piston powerplants. All the others are also found on turbines.

Manifold pressure guages are generally direct reading instruments that work off air pressure, and merely measure the pressure in inches of mercury, in the induction manifold. Older large radial engines sometimes used BMEP (Brake Mean Effective Pressure) guages. These measured torque and provided an indication of power output. Unlike the manifold pressure guage which takes an actual sampling of the air pressure in the intake manifold and transfers it to the instrument using a bourdon tube (hollow tube used to transfer fluid or gas under pressure, to the cockpit, in order to measure certain values), the BMEP sensed torque at the planetary gearbox and then gave a reading of the pressure in the cylinder...which has a direct bearing on the horsepower and torque of the engine.

Another instrument seldom seen but found only in piston aircraft is the carburetor air temperature gauge. This uses a thermocouple placed directly in the venturi throat of the carburetor, and receives the thermocouple information via special metal wires.
 

dustrpilot

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CHT, refering to cylinder head temp would only be used on a recip engine as well.
 

avbug

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True...not many turbine airplanes with cylinders these days...

CHT works using a thermocouple screwed into the cylinder head, or using a thermocouple gasket beneath a spark plug. The thermocouple is a bimetallic sensor, meaning it's got two different metals (alumul and chromel). Dissimiliar (different) metals have an electrical potential between them, which is known. By knowing this value and how it changes with the temperature of the metals, the resulting electrical microvoltage can be used to determine the temperature at the thermocouple very accurately.

The sampe principle works for other temperature gauges too, such as carb temp, exhuast gas temp, oil temp, fuel temp, etc.
 

skygirl1968

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:Dguys...thank you so much!!! this is a tremendous help...way more info than i had before and a serious base with which i can get started on researching how these instruments work!! thanks again!:beer:
 

Balou

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Also fuel flow guages can be found on some recips, read in gal/hour, and turbine aircraft as well read in pounds/hour.

good luck with the project
 
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