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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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3answers
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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 ...
41
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6answers
8k views

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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1answer
236 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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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
392 views

Why would the engine quit when turning on the R magneto after an overhaul?

I just finished overhauling a Lycoming O-360; it's currently on a stand, i.e. it's not in the aircraft. I replaced the capacitors and point gaps on both the L and R mags. I adjusted the E-gap and ...
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2answers
213 views

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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0answers
22 views

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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2answers
188 views

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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10answers
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Why do piston engines in aircraft burn fuel at a higher rate than a comparable car engine?

I've never understood why piston powered plane engines burn such a large amount of fuel per time period than car engines. Can anyone elaborate on this? I know that a C172M will burn ~5-9+ gph at ...
5
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2answers
974 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 ...
13
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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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2answers
216 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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1answer
460 views

Why would one cylinder on a Continental O-200 run cold at idle?

I have a Luscombe with a Continental O-200 engine. The #4 cylinder is running cold at idle, does anyone have an idea why? The other three cylinders are running fine. Some extra information: The ...
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3answers
130 views

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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2answers
9k views

How often should an engine be run, to stay mechanically sound?

It's winter time and many light aircraft are sitting idle. This can be detrimental to an engine's health. What is a good rule of thumb for how often a piston engine should be exercised, and for how ...
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6answers
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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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2answers
133 views

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?
3
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1answer
229 views

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 ...
5
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1answer
268 views

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 ...
3
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4answers
236 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 ...
6
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4answers
267 views

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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14answers
61k views

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) ...
4
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1answer
370 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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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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1answer
249 views

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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2answers
9k views

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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2answers
2k views

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 ...
18
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3answers
31k views

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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1answer
141 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 ...
5
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2answers
218 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 ...
16
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3answers
3k views

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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2answers
273 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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3answers
244 views

Is there a system where plane/heli auto adjusts prop pitch/mixture?

This one is simple: is there a system that automatically adjusts things such as: Mixture (I Am bored of listening for engine sounds) Prop Pitch (I Hate auto adjusting "gears") So I can ...
5
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2answers
131 views

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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3answers
484 views

Which modern day prop (piston) engines allow for inverted flight?

A buddy of mine is looking to buy an airplane with an old radial engine because he says radial engines can fly inverted in aerobatic flying. What modern day engines (engines that you can buy today), ...
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1answer
366 views

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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5answers
2k views

Why do the Lycoming HIO-360 A1A and IO-360 engines produce different power?

I have just acquired an aerobatic aircraft fitted with a Lycoming HIO-360 A1A. Reading the specs on the engine I see it has the higher (8.7:1) compression of the 200hp IO-360 engines, which seem ...
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9answers
19k 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 ...
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2answers
282 views

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
125 views

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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2answers
2k views

How does the safety record of the twin piston Diamond DA-42 compare to the single piston DA-40?

Its fairly well known that the Diamond DA-40 has one of the smallest fatality rates of any GA plane. The Diamond DA-42 is a twin engine aircraft with a very similar design to the DA-40. Now, it has ...
0
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1answer
627 views

How do turbofans and piston-engines compare in terms of maintenance costs?

I want to compare piston engines and turbofans on a maintenance basis. Let's say both engines are capable of 100 kN of thrust. Let's say both engines fly for 10,000 hours. Over that time, what kind ...
3
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2answers
329 views

Why does enriching mixture over stoechimetry give more power ?

In other words, in a piston engine, the Best Power mixture is richer than the EGT peak that signs for a stoechimetric combustion. Why is that, physically ?
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1answer
183 views

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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5answers
34k views

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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1answer
142 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 ...
10
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6answers
12k views

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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1answer
185 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
470 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
548 views

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?