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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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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 ...
blended's user avatar
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5 answers
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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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47 votes
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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 ...
AllTradesJack's user avatar
28 votes
7 answers
8k views

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, ...
Qantas 94 Heavy's user avatar
27 votes
3 answers
18k views

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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18 votes
4 answers
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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 ...
Vikki's user avatar
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4 votes
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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?
Andrea Ghilardi's user avatar
40 votes
9 answers
34k views

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 ...
DrZ214's user avatar
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22 votes
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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. ...
voretaq7's user avatar
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14 votes
2 answers
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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 ...
Garrison Neely's user avatar
2 votes
1 answer
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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 ...
DrZ214's user avatar
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45 votes
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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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25 votes
9 answers
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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 ...
Simon's user avatar
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15 votes
6 answers
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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 ...
Farhan's user avatar
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14 votes
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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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12 votes
2 answers
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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 ...
Qantas 94 Heavy's user avatar
9 votes
2 answers
4k views

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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35 votes
14 answers
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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) ...
Jan Hudec's user avatar
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34 votes
2 answers
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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 ...
Jamiec's user avatar
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25 votes
2 answers
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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 ...
JamesENL's user avatar
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24 votes
3 answers
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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 ...
raptortech97's user avatar
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22 votes
3 answers
10k views

Carbureted 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?
falstro's user avatar
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21 votes
3 answers
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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 ...
Qantas 94 Heavy's user avatar
21 votes
4 answers
7k views

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 ...
Charles847's user avatar
19 votes
3 answers
92k views

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 ...
ha9u63a7's user avatar
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15 votes
4 answers
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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 ...
abey's user avatar
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14 votes
1 answer
13k views

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 ...
Steve V.'s user avatar
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9 votes
3 answers
26k views

Are there any pressurized piston-engine aircraft?

Are there any pressurized piston engine-powered aircraft? Or does pressurization require a turboprop or jet?
TayE's user avatar
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8 votes
1 answer
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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% ...
Mirajul.Pias's user avatar
7 votes
1 answer
2k views

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. ...
Skip Miller's user avatar
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6 votes
2 answers
4k views

Why does pulling the mixture to idle cutoff increase the RPM slightly?

When adjusting fuel control on a reciprocating engine, why is there a slight RPM rise (50-RPM rise) when pulling the mixture control to idle cutoff? Why if more than a 50-RPM rise, carburetor is set ...
StevenH88's user avatar
5 votes
4 answers
3k views

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 ...
Andrius's user avatar
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4 votes
2 answers
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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 ...
ryan1618's user avatar
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4 votes
4 answers
556 views

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 ...
DrZ214's user avatar
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4 votes
2 answers
1k 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)?
Michael Hall's user avatar
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2 votes
3 answers
889 views

Is a recoil start (hand propping) allowed if it isn't mentioned in the aircraft manual?

Is a recoil start (hand propping) allowed without it being referenced in the aircraft manual? In a Cessna 150, for example.
Ygor Montenegro's user avatar
55 votes
6 answers
26k views

Why do most radial engines use an odd number of cylinders?

To help suppress vibration, most 'V' and 'horizontal' engines use an even number of cylinders as closely opposed as possible. Radial engines are well known for excessive vibration. For some reason ...
jwzumwalt's user avatar
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32 votes
4 answers
8k views

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.
TayE's user avatar
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25 votes
6 answers
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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 ...
Zaz's user avatar
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24 votes
2 answers
6k views

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 ...
Jae Carr's user avatar
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19 votes
3 answers
11k views

Why did the turbojet replace the piston engine?

Many people say that this was because aircraft powered by turbojet engines were faster during WWII. However the Grumman F7F-4N Tigercat, a fighter powered by a piston engine, flew at a maximum speed ...
Elena Mueller's user avatar
18 votes
3 answers
5k views

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 ...
Jan Hudec's user avatar
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17 votes
2 answers
2k views

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 ...
Steve V.'s user avatar
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16 votes
2 answers
15k views

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 ...
Mirajul.Pias's user avatar
15 votes
2 answers
8k views

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 ...
Canuk's user avatar
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15 votes
4 answers
11k views

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 ...
MissMoira's user avatar
  • 151
14 votes
3 answers
7k views

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 ...
aaronstran's user avatar
13 votes
4 answers
2k views

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 ...
Darren Hill's user avatar
13 votes
1 answer
2k views

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 ...
voretaq7's user avatar
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12 votes
2 answers
3k views

Why does using carburetor heat increase fuel consumption?

As written above, why does using carburetor heat increase fuel consumption? Because I found such information in a few SOPs for piston airplanes and I do not understand why does it happen
Konrad's user avatar
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