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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27
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3answers
13k views

Why are propeller engines uncommon on airliners?

My experience in aviation is essentially zero, but looking at Wikipedia it seems like the Tu-95 Bear offers high subsonic speed and extreme range. I assume that turboprop engines are more fuel ...
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What are the differences between fuel types (comparing with vehicles)?

I find it funny that at gas stations, generally you can purchase "regular" gasoline (in various octane levels) or diesel. At airports, generally you can purchase 100LL avgas or Jet-A. Can you compare ...
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What are some of the differences between piston engines used in aircraft and automobiles?

What are some of the differences between piston engines used in aircraft and automobiles? It seems aircraft engines are much more expensive, I imagine some of that cost must be due to the more ...
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How can reducing power too quickly on a piston engine damage it?

In many places, it's been stated that you should reduce power slowly to prevent engine damage. Depending on who you talk to, some say you should reduce the manifold pressure by 1 inch per minute, ...
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3answers
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Why are piston engines for aircraft rarely diesel powered?

Why hasn't diesel caught on much for aircraft engines? The list of diesel aircraft engines on Wikipedia is very short. The reason I see mentioned is their poorer power-to-weight ratios. (e.g. What ...
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4answers
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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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2answers
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In high-altitude piston aircraft, what type of forced induction (boost) is used?

In high-altitude piston aircraft, what type of forced induction (boost) is used? Turbocharger or supercharger?
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9answers
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Why increase the number of cylinders in an engine instead of increasing their volume?

I've been reading about WW2 planes lately. Some of them have 12 or even more pistons in their engines. But if your goal is to increase power, why would you add more pistons instead of simply ...
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What is the difference between SMOH and SFOH?

When looking at aircraft for purchase online, a lot of acronyms are used. In particular, the SMOH and SFOH acronyms are thrown around a lot for used aircraft. What are the differences between these ...
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When is pre-heating a piston engine important, and how does one pre-heat correctly?

As temperatures here in New York plunge toward (and below) freezing it's time for those of us without nice heated hangars to start thinking about pre-heating our aircraft before we turn the key. ...
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Why does manifold pressure increase with power?

Whilst writing an answer to this question, I remembered something I don't really understand. The partial vacuum in the inlet manifold is caused by the piston descending with the inlet valve open ...
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6answers
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Why are propeller airplanes still made?

Airplanes with propellers were invented a long time ago. After that, jet engines came into existence. My question is: why do we still have propeller engines? The reasons I can think of are: They are ...
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How to calculate the thrust of a piston or turboprop engine? [duplicate]

This spawns from a related question. Propeller-drive engines (piston/turboprops) seem to always list their output in horsepower or kilowatts, which are units of power. I want to know the engine's ...
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2answers
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How does aircraft design affect carburetor ice?

The Cessna 172 and Piper Warrior are similar in many ways, including their engines: for most of their production history (1968-1998 for the 172; the entire history for the Warrior) both were equipped ...
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14answers
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Why don't small planes use turbine (turboprop) engines?

Turboprop engines are more fuel efficient1, lighter for the same power, mechanically simpler and consequently more reliable. They are also slightly easier to operate (no need to fiddle with mixture) ...
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Why is water-contaminated fuel bad, but water-injection is not?

A "wet" takeoff of a KC-135 with J57 engines—By USAF Photographer (USAF photo) [Public domain], via Wikimedia Commons Why is water-contaminated fuel bad, but water-injection is not? The way I ...
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3answers
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Why the lack of faster piston-powered planes?

There aren't very many fast piston airplanes in production. By "fast" I mean, if you look back in the early to mid 20th century, before turbines won out, there were lots of piston airplanes in ...
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What are the advantages/disadvantages of diesel/Jet A-1 piston engine?

Some GA aircraft, notably the DA40/DA42, are equipped with piston engines that use Jet A-1 and/or automotive-grade diesel instead of aviation gas (avgas). An example of such engine is the Austro ...
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3answers
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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?
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What is “detonation” in a piston engine?

Recently, I saw this question, which included a rather alarming quote: Full throttle operation with carburetor heat on can cause detonation. Woah! That doesn't sound good. In fact, I would have ...
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Are there any pressurized piston-engine aircraft?

Are there any pressurized piston engine-powered aircraft? Or does pressurization require a turboprop or jet?
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4answers
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Why don't airplane turbo piston engines have boost control?

Why is it possible to over-boost piston aircraft engines? All turbo car engines have a wastegate that just vents pressure back to the intake, whereas in an airplane the pilot has to look at the ...
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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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Is the Soloy Dual Pac recognised as two engines or one engine?

The Soloy Dual Pac apparently allows two engines to rotate one propeller -- here's a picture of it on an Otter: Is this recognised as a centreline thrust twin engine aircraft, a "standard" twin ...
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1answer
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What is my BHP if I open full throttle and how is it controlled?

In my Cessna 152 POH it is written that the horsepower rating is 110BHP at 2550RPM. My question is: is it 100% of the power of my engine or, as someone told me, if I open full throttle I will get 75% ...
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Where to find Tach hour and clock hour equivalence rpm?

There is a revolution counter built into the face of the Tachometer in most piston powered GA planes. This counter is calibrated in hours. Most planes also have a Hobbs meter, which is a clock. ...
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How reliable are Lycoming and Continental general aviation piston engines?

Statistically speaking, how reliable are Lycoming and Continental general aviation piston engines? What I'd really like to either find or build is a table showing the probability of experiencing ...
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What was the first aircraft that could fly inverted?

I'm taking a guess and assuming the Wright Flyer was incapable of flying upside down. I'm just guessing it probably lacked the power... ;) So what was the first plane that could fly inverted for a ...
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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 does the lack of a magneto affect engine RPM?

So I don't have my pilots licence, but I was part of the Australian Air Force Cadets for nearly 8 years (wonderful organisation). During this time I went on a number of flights in Cessna 172's and ...
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Is it possible to hand start modern planes?

I know that older planes must be hand started but are newer GA planes even able to be hand started by spinning the prop? If so, how do you do it safely without cutting your hands off or being pulled ...
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2answers
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Starting on the left magneto only - why?

I had been flying a PA-28 Archer III for quite a few months before I sat down to properly read through the POH. Something stood out to me about the starting procedure (emphasis mine) Open the ...
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How does the mixture of an engine affect the engine's operation?

I know that in most piston aircraft that there is a mixture control for the engine. My question is, how does the mixture control affect the engine's operation and what type of situations dictate a ...
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Why do aircraft piston engines require priming?

Aircraft piston engines generally require priming, but automobile engines don't seem to need it. Why doesn't cranking the engine with the starter pull in fuel mixture that would ignite without help of ...
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3answers
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What does feathering mean and how does it work technically?

Before I ask "What does Feathering mean when it comes to Jet/Propeller Engines" I have to say what I think I know: Feathering jet/prop engines mean achieving a sufficient turbine rotation speed at ...
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2answers
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Why is the magneto drop check done at 1700 RPM?

In our Cessna 152, we carry out the mag drop check at 1700 RPM, following the POH. My question is why it is done at 1700 RPM? What will happen If I check it at 2000 RPM or less than 1700 RPM? And if I ...
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3answers
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Rotax engines have no mixture control, how do they handle less dense air?

Rotax engines have no mixture control, yet they don't seem to have any more problems than other engines at altitude. How do they handle the lower air density in order to not get a too rich a mixture?
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Why does carburetor icing require manual attention by the pilot?

Why is it carburetor icing has to be handled manually by the pilot, at least in a helicopter? I am hoping very soon to take my PL/H lessons, I have a little understanding of mechanics and how things ...
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1answer
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What appears on EGT Gauge if the mixture is rich or lean?

I have some questions on interpreting Exhaust Gas Temperature (EGT) readings. Can you give me some input on: What appears on EGT Gauge if the mixture is lean or rich? what is the normal range, ...
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Why isn't the APU a standard diesel generator?

Why isn't the APU a standard diesel generator? Jet-A and diesel are interchangeable (with the addition of a lubricant). So why not use a cheaper piston engine as opposed to a jet turbine? V.S.
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Why is carburetor heat use discouraged on the ground?

I've been reading my private pilot books for when I start in February and Carb Heat has me stuck in a rut. I feel like I need to have a very solid understanding of this being that I live in a very ...
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1answer
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Why does manifold pressure increase when you turn on carb heat?

So everyone knows that carb heat decreases engine performance. Yet when we check the heat during run-up, the manifold pressure increases. Why is that? Shouldn't adding carb heat cause the intake air ...
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6answers
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Why is full carb heat recommended when reducing power below normal setting?

In my first flight lesson today, my instructor asked me to apply full carburetor heat when we had to reduce power to 1900 RPM in our Cessna 152. I was surprised by this as I didn't remember learning ...
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How does skydiving flight cause shock cooling?

While answering this question (How can reducing power too quickly on a piston engine damage it?), barit1 said that: Skydiving planes see a LOT of shock cooling, and they pay for it at overhaul time ...
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2answers
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Why did the manifold pressure gauge on the Ki-61 have negative values?

The manifold pressure gauge of the Japanese Ki-61 has values which go from +40 to -40. I know this has to be relative to something since negative pressure can't exist (you can't get more vacuum than a ...
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4answers
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Should I have carb heat on for landing in a C152?

There is quite a debate about this! I'm a student, have gone solo. My first instructor insists the carb heat goes off/COLD on the approach ('ready for go-around' if needs must! And to prevent dirty ...
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2answers
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Why/How does a “Powerflow” exhaust increase horsepower?

I've seen airplanes (typically Cessna 172s) with a "Powerflow" exhaust system and then claim to get several more horsepower, resulting in faster cruise speeds. How does a Powerflow exhaust work, and ...
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1answer
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What should I look for / check during an oil change?

Piston aircraft engines require regular oil changes, and at least in the US it's something the FARs allow an owner with a private pilot certificate to do. What are some of the things I should look ...
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1answer
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Why are some fuel-injected engines started with the mixture at idle cut-off?

The POH for a C172N with a carbureted Lycoming O-320 says: STARTING ENGINE Mixture -- RICH Carburetor Heat -- COLD Master Switch -- ON Prime -- AS REQUIRED Throttle -- OPEN 1/8 INCH ...
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2answers
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How is horsepower measured for aviation piston engines?

As far as I can tell, aviation piston engine power output is typically measured in HP (horsepower). Automotive engine power output is typically measured by running the host vehicle on a rolling road, ...