Questions tagged [piston-engine]

Piston (reciprocating) aircraft engines are internal combustion engines, similar to the type found in most automobiles. They are typically gasoline powered.

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3answers
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Why are engines with carburetors hard to start in cold weather?

Why are engines with carburetors hard to start in cold weather? And why is there a different procedure for hot start scenarios, after you've just shut down the engine and want to power up again?
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Where do the compressed gasses of a charged engine goes?

Good day to you here. I'm working on a modified version of 2-stroke engine. My plan is to use a supercharger for the scavenging process, instead of the conventional Crank case scavenging technique, ...
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How can I decode Lycoming engine number?

How can I decode Lycoming engine number suffices? What does D3G mean in o-320-D3G or D2A in o-320-D2A? Is there any chart or tabel for decode suffixes?
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Why are two-stroke engines nearly unheard of in aviation?

Almost all aircraft piston engines are four-stroke engines, with one power stroke per piston every other crankshaft revolution and a great deal of intricate moving parts which are only too happy to ...
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What are the durations of strokes and events in a 4-stroke engine?

I'm learning about engines, and I understand the basics of how a 4-stroke engine works, but I've seen lots of true or false questions such as "The power stroke is shorter than the intake stroke" or "...
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1answer
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Is there an actual rated thrust for a Cessna 172 engine at takeoff power?

I could approximate the thrust by knowing the weight of my aircraft and timing the acceleration to takeoff speed, but I think that would be a little dangerous of me as well as only an approximation ...
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1answer
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What is the metal bit in the front of this propeller spinner?

What is that grey spirally bit in front of the propeller mounted on this Shvetsov ASh-62 radial engine?
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61 views

Determining total engine life in relation to SMOH/SFOH

When evaluating the value of an aircraft, the total hours since major (or factory) overhaul (SFOH/SMOH) is an important indicator of price since it tells us how many hours the engine has operated ...
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1answer
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Causes of High CHTs

I have a Long EZ with a Lycoming O-320 E2D. It had a complete top-end overhaul two years ago, in June 2017. All four cylinders were relined, and pistons and rings were replaced. Since then the ...
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1answer
607 views

Does the mixture and throttle setting affect the quality of priming of fuel prior to start?

This question is a generality. For airplanes with small reciprocating engines, does the mixture and throttle setting at the time of priming affect the quality of the priming or the engine start, or ...
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2answers
158 views

What is the difference between an engine “shut down”, “cut-off” and “cut down”?

Explain please for non-native speakers the difference between these engine (jet or piston) terms: shut down cut-off cut down I'm studying at a civil aviation university to become a pilot and a ...
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1answer
205 views

How do you lean mixture using only the instruments on a C172 Skyhawk?

POH manuals always tells to use the voice of the engine as a reference. (Which complicates things a little bit since carbs and fuel injected planes have different "reaction times" for each cylinder) ...
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How is crankcase ventilation handled in R-2800?

I just finished R-2800: P&W's Dependable Masterpiece and noticed there's no mention of a pump for crankcase ventilation. Is this handled by the oil scavenge pumps?
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2answers
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How do I estimate piston aircraft fuel efficiency?

Is there any way to figure out or calculate fuel consumption of piston engines for aircraft? I'm looking at different engines in a book, and while jet engines have useful values like thrust, bypass ...
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2answers
390 views

Why is the fuel pump in the startup procedure for a Cessna 172?

I thought fuel pumps were reserved for fuel injected planes in startups and during critical flight phases for all planes? However. There are some X-Plane flight tutorials that tells us to use fuel ...
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3answers
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How do carbureted and fuel injected engines compare in high altitude?

I couldn't find enough information on the internet for this topic. What I found can be paraphrased as: Carburetor means easy engine start while fuel injected means manual fuel start up and ...
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2answers
157 views

What modifications are required for automotive fuel STC?

What actual engine modifications are required to allow certificated piston engined general aviation aircraft to run automotive fuel under an FAA Supplemental Type Certificate (STC)?
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1answer
137 views

Why do the Diamond DA-42 and DA-62 have a minimum fuel temperature requirement?

On the turbo diesel DA-42 and DA-62 aircraft there exists a minimum fuel temperature limitation where you may not start or operate the aircraft below that. Does anybody know why this is? It seems ...
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0answers
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Do ARFF units need special equipment for responding to crashes or fires involving piston-engine aircraft?

Unlike jets and turboprops, which generally burn (relatively) benign jet fuel (usually a straight kerosene, occasionally with plain gasoline blended in as a freezing-point depressant), piston-engined ...
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1answer
381 views

Why are piston-engined aircraft generally exempted from U.S. flight recorder requirements?

Most, if not all, of the FAA’s requirements for carriage of flight recorders do not apply to piston-engined aircraft. For instance, 14 CFR 91.609(c)(1) (emphasis added): No person may operate a U....
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2answers
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Why would a C150 tachometer be sluggish?

After having an issue with a tachometer bouncing so much that it fell off, I now have the opposite problem with the replacement (Mitchell D1-112-5025): The tachometer is sluggish. When I open the ...
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2answers
1k views

What is the blue range indicating on this manifold pressure gauge?

This is baffling me. Does anybody with experience with this type of indicator have any idea what the blue range of this gauge means? It's mounted in a mock-up panel. I know nothing about where it ...
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2answers
247 views

Why would a cylinder not work below a certain RPM?

We have an IO 540 Lycoming engine, and cylinder #3 doesn't work below 1900 RPM (cold to the touch; EGT and CHT are zero; no vibration). The engine is new, what could be the cause(s)? We cannot ...
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Why is carburetor heat unnecessary at full throttle?

Questions like How does aircraft design affect carburetor ice? show how carburetor mount point affects the relative passive heating of the carburetor by the engine, but I've never learned why full ...
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Why would a C150 tachometer bounce so much that the needle fell off?

On a long flight in a C150E, the tachometer started bouncing a little bit and the severity of the bouncing gradually increased until it was extreme: The tachometer was spinning in loops and making a ...
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Why did most WWII Allied piston engines not use fuel injection?

One would think that given the huge push for ever more performance and reliability on piston engines during the heat of WWII would push the designs to their absolute limits, however, most American ...
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What is the main reason of air-cooled radials producing much less HP/L compared to liquid cooled Vs?

Is it because of the inherent limitations of cooling the cylinder walls, only 2 valves per cylinder, relative ease of scaling up instead of dialing up the boost, or some other reason?
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Is the Meredith effect utilized in the cowling design of air-cooled engines?

The P-51 is famous for its advanced-for-its-time aerodynamics, the prime example of which is the radiator design under the belly which utilizes the Meredith effect to, in effect, turn it into a mini ...
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Why do carburetors tend to produce richer mixture at higher altitude?

The pressure drop in the venturi is proportional to air density and the fuel is at ambient pressure in the float chamber, so I would expect the fuel flow to reduce proportionally with density, and ...
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1answer
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Are WWII turbochargers reliable?

How reliable are WWII turbochargers? Does adding them to an otherwise reliable engine, e.g. the P&W Double Wasp and the Allison, decreases the overall reliability of the engine? Are they well made ...
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4answers
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What changes are needed for a piston-prop aircraft to withstand saltwater environment?

I'm interested in WW2-era piston-prop aircraft. I want to know what changes are needed to make the aircraft withstand saltwater corrosion. Presumably these are different and more expensive than the ...
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1answer
663 views

Why don't air-cooled radial engines use fuel to cool the oil?

Having read up on WWII air-cooled radials, one thing that struck me is how frequent is the mentioning of external oil cooler overheating, or the need for armored boxes around it, and some even venture ...
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Why are piston engines so unreliable in airliners?

Before the first jetliners appeared, all airliners used piston (reciprocating) engines, which were astoundingly prone to failing in flight, to the point where an inflight engine failure was an ...
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Why would you NOT lean on takeoff with a Lycoming engine?

There is an excellent question/answer on leaning here. However what I have not yet understood is why one would NOT lean for takeoff below 3000 feet? Why does the Lycoming Service Directive 1497A/B ...
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1answer
155 views

What is the cooling air exhaust velocity for the piston engine of a propeller driven aircraft?

Piston engines of propeller driven aircrafts need to be cooled. There are engine cowlings which accomodate the inflow of air to "wash" over the engines within them and which is then exhausted out into ...
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Why cycle the magnetos before engine shutdown?

Inspired by this question asking about shutting down a light aircraft engine I realised there is another ritual which I do, but have long forgotten the reason why. Having parked a light aircraft, and ...
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Why in the Seneca 2 the Rated Horsepower are higher at 12000 feet than at sea level? (215Hp at 12000feet, 200Hp at sea level)

Reading the POH I found that the Rated Horsepower at 12000 Feet are higher compare to sea level. I have in the past studied the back pressure of the exhaust gasses but I cannot completely understand ...
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1answer
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Why did the Daimler-Benz DB 605 compression ratio vary between cylinder banks?

The Daimler-Benz DB 605 was an inverted V12. The compression ratio of the 2 banks varied slightly. Why did the designers do this? Compression ratio: 1:7.3 right bank, 1:7.5 left bank (museomotori....
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2answers
436 views

How does the throttle position affect the speed of airflow to the engine?

It is said that the less we open the throttle the slower is the speed in Venturi tube, thus less reduction in pressure and less fuel is being sucked from float chamber, however, actually if we reduce ...
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2answers
293 views

Does engine oil have a shelf life?

Suppose that I buy a case of oil. For some reason I stop flying and the oil sits in storage for a sufficiently long time. After that, I decide I want to put it in my engine. Is there a point after ...
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In a piston aircraft engine, how much heat must be removed by the oil cooler?

It is pretty straightforward to compute the heat and power generated by the combustion process, given the displacement, RPM and fuel mass flow rate. Similarly, the power exhausted can be computed with ...
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1answer
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Do two stroke engines for small aircraft suffer from degradation between overhauls?

Do two stroke engines for small aircraft suffer from degradation between overhauls? For an automotive engines you can usually expect it to retain most of it's power between services for a long time ...
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Why does enriching the mixture ratio beyond stoichiometry give more power?

In other words, in a piston engine, the best-power mixture is richer than that producing the EGT peak that signals stoichiometric combustion. Why is that, physically?
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1answer
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How to lean with constant speed prop on multi-engine aircraft without EGT

This question is more about the indication of engine roughness. The procedure for leaning without an EGT is clear in the POH and Lycoming documentation which basically states as follows: Best power: ...
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1answer
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Is this test question correct about the causes of detonation?

So detonation is explained brilliantly in the answer of this question. In the accepted answer, NathanG goes on to say the following: the octane rating of a fuel is basically the amount of pressure ...
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1answer
564 views

How does a rotary piston (radial) engine work?

How does a Gnome rotary piston engine work? I would like to see how it works in detail, possibly with text explanation.
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1answer
217 views

How much extra weight is added by strengthening a piston-prop fighter for carrier landings?

To land on a carrier, an aircraft must be strong enough to withstand sudden deceleration by the tail hook catching the arresting wire. I think it also requires strengthening the undercarriage to ...
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1answer
166 views

Voltage induced in high-tension magneto ignition system

Why is there no voltage induced into the secondary winding (in high-voltage step-up transformer) when the ignition switch is closed (OFF). When the current flows in the primary winding of the coil a ...
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1answer
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Why does fuel vaporize in the carburetor?

So I get that a carb vaporizes fuel and mixes it with the air intake for the engine. But my question is what is the explanation for what causes the fuel to vaporize after it exits the fuel nozzle?
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What is a biplane propeller and how efficient is it?

Lazair ultralight series II used biplane props to absorb more power from the engine....so my question is what really is a biplane propeller and are they efficient in comparison to a four bladed prop?