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83 votes
Accepted

Why is jet fuel cheaper than piston fuel?

Jet-A (and all turbine fuels) are far cheaper than 100LL (at least in bulk; retail prices vary due to local supply and demand as well as different regional tax regimes on aviation fuel) for several ...
UnrecognizedFallingObject's user avatar
78 votes
Accepted

How can an altimetry system error during cruise (500 ft at 35000 ft high) cause an insufficient fuel situation?

If the aircraft is cruising at FL350 it is operating in Reduced Vertical Separation Minima (RVSM) airspace (between FL290 and FL410). With an altimetry discrepancy between the two altimeters of more ...
DeltaLima's user avatar
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55 votes
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Why is water-contaminated fuel bad, but water-injection is not?

Because of the quantity of water in the fuel, as opposed to a careful introduction of water into the combustion process. Typical water contamination is bad in fuel tanks as water is denser than ...
Romeo_4808N's user avatar
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48 votes
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Is it cheaper to drop cargo than to land it?

That scenario only makes sense if your airplane stays at cruising altitude: although taxi and takeoff does use up fuel it's really the ascent to cruise that takes the most. You aren't really going to ...
GdD's user avatar
  • 54k
47 votes

Is fuel moved around during flight on a passenger or cargo plane? If so why?

Maybe This is dependent on the air frame and varies from plane to plane and not all planes have capability of moving fuel although most large planes do. The Concorde moved fuel all over the place ...
Dave's user avatar
  • 101k
47 votes
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Why don't we see business jets with wingtip fuel tanks anymore?

One of the main reasons wing tip tanks were used was to counteract some of the forces of wing bending by adding mass to the end of the wings. As time has progressed and our understanding of materials ...
Dave's user avatar
  • 101k
39 votes

Could most commercial jet engines today run on ethanol without any problems?

Although turbines could be designed to run on ethanol it's actually a lousy aviation fuel (actually it's a lousy fuel in general). Petroleum-based jet fuel is high grade kerosene which has lubricant ...
GdD's user avatar
  • 54k
35 votes
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What happens if you do emergency landing on a US base in middle of the ocean?

Wake Island has had aircraft divert there before, as it serves as an ETOPS diversion airport. Per the remarks on AirNav and the NOTAMs: RSTD: VERY LIMITED OPERATIONS STATUS, AVBL FOR EMERG LDG AND ...
fooot's user avatar
  • 73.4k
34 votes

Does a 120cc engine burn 120cc of fuel a minute?

This is possible, but still quite extreme fuel consumption. 120ml == 120cc gasoline are ~90g by mass 90g gasoline need about 1320g air in order to fully combust 1320g air are about 1.08 cubic meters ...
fraxinus's user avatar
  • 1,543
33 votes

Is it cheaper to drop cargo than to land it?

Looking purely at operational cost of the aircraft, yes. You save time, burn less fuel, don't have to pay for the landing etc. But dropping the cargo makes the cargo more expensive. You have to ...
Hobbes's user avatar
  • 10.2k
31 votes

Why is jet fuel cheaper than piston fuel?

There are a number of factors that go into it: Economies of Scale Jet-A is used in a much higher volume than 100LL. All the jet engine commercial aircraft each day burn through orders of magnitude ...
Ron Beyer's user avatar
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30 votes
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Why do piston engines in aircraft burn fuel at a higher rate than a comparable car engine?

As others have noted, airplane engines and car engines have very different duty cycles. An airplane engine will typically run at full power for a few minutes during takeoff & climb, then at a ...
jamesqf's user avatar
  • 2,577
28 votes

Why is water-contaminated fuel bad, but water-injection is not?

Water-injection in jet engines and piston engines is mixed with fuel before it enters the combustion This is actually somewhat wrong (or at least imprecise) and I think it is adding to the ...
justinm410's user avatar
28 votes
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What features enable the Su-25 Frogfoot to operate with such a wide variety of fuels?

Being a ground attack aircraft, the Su-25 has an operational ceiling of 23,000 ft and will not encounter the low temperatures to which a Boeing 777 is regularly exposed. Therefore, the risk of diesel ...
Peter Kämpf's user avatar
27 votes
Accepted

Why would a fighter drop fuel into a drone?

I read about four possibilities which the SU-27 pilots wanted to enforce: a) Covering the drone in fuel and then igniting it with the afterburners which should have lead to a fire and subsequent ...
U_flow's user avatar
  • 3,840
26 votes

What makes a smokeless jet engine?

Generally, smoke comes from incomplete burned fuel. Normally, a jet engine burns a very lean mixture (due to turbine temperature constraints). Nevertheless, getting all the fuel to burn is a ...
Zeus's user avatar
  • 9,083
26 votes

Where does Air Force One refuel?

I can't confirm whether either VC-25 has refueled in flight while acting as AF1 but the aircraft is so equipped for the job. I do know refueling on the ground depends on where the jet is and the ...
Romeo_4808N's user avatar
  • 74.1k
26 votes

Has anyone burned hydrogen in a gas turbine?

Yes, indeed the plan to build a hydrogen-powered jet laid the groundwork for using hydrogen in the Centaur rockets and the upper stages of the Saturn 5. While hydrogen was used only experimentally in ...
Peter Kämpf's user avatar
26 votes
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How does a jet engine burn fuel when it is not on an afterburner?

The regular way to burn fuel is not to use an afterburner. The afterburner is an option added downstream of a regular engine to increase its thrust temporarily. It is an interesting alternative to ...
mins's user avatar
  • 74.7k
26 votes

Does a 120cc engine burn 120cc of fuel a minute?

No, a 120cc engine does not burn 120cc of fuel per minute. It means that the sum of the volumes of space swept by the pistons in each of the cylinders equals 120cc. This is called engine displacement....
Someone's user avatar
  • 7,097
25 votes

Is fuel moved around during flight on a passenger or cargo plane? If so why?

Yes fuel is moved around, and balance is indeed an issue. The A330 has trim tanks in the horizontal stabiliser, and so does the A380. Fuel can be stored there to balance the aircraft - without trim ...
Koyovis's user avatar
  • 61.8k
25 votes

Is fuel moved around during flight on a passenger or cargo plane? If so why?

In 747-100/200 aircraft, takeoff was accomplished tank-to-engine (meaning each engine was fed from it's corresponding main tank). After takeoff the fuel burn schedule called for center tank fuel to be ...
Terry's user avatar
  • 39.2k
25 votes
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How can flying high minimize drag and increase fuel efficiency?

Flying higher means less drag because the air is thinner; therefore, you can fly faster at altitude and hence travel farther on less fuel. However, flying higher also means less oxygen available to ...
niels nielsen's user avatar
25 votes
Accepted

How to safely handle AVGAS (100LL)?

If you don't crawl underneath and breathe in the exhaust fumes from the engine, you'll be fine. If you do crawl underneath and breathe in the exhaust fumes, you'll be dead from carbon monoxide ...
John K's user avatar
  • 132k
24 votes

Why don't we see business jets with wingtip fuel tanks anymore?

More modern engines need less fuel for the same thrust, so the fuel volume needed for an acceptable range has shrunk over the last five decades. Wing volume alone is now more than sufficient. While a ...
Peter Kämpf's user avatar
24 votes
Accepted

How do pilots detect fuel contamination in flight?

If fuel contamination is suspected (because of engine control system fault indications, slow engine responses or rapid engine pressure ratio (EPR) fluctuations), there is an associated checklist ...
DeltaLima's user avatar
  • 83.5k
24 votes

Is there any work on improving fuel tanks so they could store hydrogen?

First, to debunk a myth regarding the Hindenberg, which always gets brought up whenever hydrogen is mentioned. Hydrogen is less safe than liquid fuel, but it is not less safe than natural gas or ...
Level River St's user avatar

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