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Questions tagged [fuel]

Different aircraft engines use different fuels; the most common types are Jet A or A-1 for jet and turboprop engines, and avgas for piston engines.

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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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28 votes
2 answers
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What are the ICAO fuel reserve requirements?

How much reserve fuel are private and commercial aircraft required to carry by ICAO rules? I heard that it changed recently (about a year ago) and is a little complicated. How is it calculated for ...
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35 votes
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Which engine is more efficient between turboprop vs jet?

Are turboprops really more efficient than jets? If yes, does that mean that airlines who use jets sacrifice fuel for faster flights?
Taher Elhouderi's user avatar
90 votes
5 answers
48k views

Why does the F-111 sometimes squirt a giant fire plume behind it? (NOT afterburners!)

As seen in multiple pictures: First, this one, it appears the aircraft is spraying copious amounts of fuel into the exhaust! Surely this provides no thrust, not in the way an afterburner (which the ...
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4 votes
2 answers
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Are there any programs to build a hydrogen powered airplane?

So called "renewable energy" is a buzzword these days. Auto manufacturers are starting to roll out hydrogen powered cars. Hydrogen may not currently be the most efficient or economic fuel for jet ...
digitgopher's user avatar
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71 votes
6 answers
123k views

Why do jet engines use kerosene rather than gasoline?

Could you run a jet with gasoline? Why do all jet engines use kerosene?
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18 votes
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What is the cost savings of using electronic motors to taxi?

Aircraft manufacturers are now planning to use High Torque electric motors on the nose wheel of the aircraft, which is powered from the APU, to taxi the aircraft from the gate to the runway without ...
Victor Juliet'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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23 votes
2 answers
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What happens to incoming flights when the airport shuts down?

In Die Hard 2 terrorists take over an airport's ILS and landing lights on a snowy night (visual landing is impossible) and start making threats essentially holding the planes hostage. The tower ...
ratchet freak's user avatar
18 votes
4 answers
6k views

Do I have to declare an emergency if I cut into fuel reserves?

In another question, I wrote You only need to plan for regulatory reserves. You don't actually have to land with them and @Jan replied: you have to declare emergency if you do cut into them though ...
rbp's user avatar
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12 votes
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How much fuel does it take to start/land an aircraft, compared to normal flight?

I'm wondering how bad it is to fly a short distance, such as ~50km, with a big airplane. How much less fuel does it take to fly at high altitudes compared to low? And how much of the fuel is spent on ...
Filip Haglund's user avatar
9 votes
2 answers
9k views

Do fighter jets have a traditional inverted fuel system?

Common solutions for aerobatic piston singles is to have either header tanks (for wing tanks, as I understand it) or flop tubes (for fuselage tanks). Do fuel systems in a fighter jet work on the same ...
falstro's user avatar
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6 votes
3 answers
5k views

What is the relation between drag and weight?

Given an aircraft type and fixing its wing configuration (flaps, slats) and fixing its speed and altitude and assuming it flies horizontally, what is the relationship between the aerodynamic drag and ...
polaris12246's user avatar
5 votes
2 answers
1k views

At what point during a long flight do commercial airliners have the best gas mileage?

This question has several parts that are interrelated, and I didn't want to split it up: Considering that several tons of fuel are consumed during a long haul flight which requires lift to be reduced ...
yippy_yay's user avatar
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39 votes
3 answers
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How do aircraft keep fuel from freezing while in flight?

On aircraft which fly above 30,000 feet, the temperature can often can get to temperatures below Jet-A's freezing point. For example: at 36,000 feet the standard outside air temperature is -56.5°C (-...
Qantas 94 Heavy's user avatar
26 votes
5 answers
5k views

Why is fuel usage discussed per time, not per distance?

I don't understand why sometimes the fuel used for a flight is discussed in terms of fuel used per time. I think I have seen it a couple of times here - not sure whether it was in some common context. ...
Volker Siegel's user avatar
25 votes
7 answers
12k views

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

Most commercial jet engines today would be those large jet engines on large passenger craft like a Boeing 747. Can these run on straight ethanol without any problems? Would more maintenance be ...
DrZ214's user avatar
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16 votes
2 answers
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Does the APU consume a lot of fuel compared to a jet engine?

I would like to know whether the APU of modern commercial airliners consumes more or less fuel than a jet engine. Of course, this will vary between aircraft types, so what comparisons in fuel usage ...
Manu H's user avatar
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13 votes
1 answer
1k views

Why might a passenger jet fly at altitudes in a strong headwind when the winds are more favorable at a different altitude?

I was a passenger on an east to west flight recently. During the flight I was playing with Garmin Pilot's new "Flight profile" feature that nicely shows the wind speeds at various altitudes, and I ...
Greg Taylor's user avatar
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11 votes
3 answers
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When is a fuel pump needed on GA aircraft?

When is a fuel pump needed on GA aircraft? I am a flight simmer and have noticed that you can leave the fuel pump off and start/fly the aircraft. When would you use the fuel pump?
IVAO CA-WM's user avatar
45 votes
6 answers
10k 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 ...
user avatar
29 votes
3 answers
13k views

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

There is something I miss from the Learjet 35 (one from FS95/98) that I don't see any more: Fuel tanks on the wingtips! What happened to the wingtip integrated fuel tanks in the business jet industry?
Delta Oscar Uniform's user avatar
19 votes
3 answers
17k views

Why is AVGAS so much more expensive than car gas?

Why is 100LL so much more expensive than gasoline for cars? I get the fact that it's 100LL, instead of 87, 91, etc. For example (as of now, 13 Oct 14), the 91 unleaded gas at my local gas station is ...
Keegan's user avatar
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15 votes
2 answers
3k views

Under what conditions are passengers required to take precautionary measures during refueling?

I was on a recent flight with a fuel emergency, during which the passengers were required to take precautionary measures. Under what circumstances are the precautionary measures mentioned below ...
dotancohen's user avatar
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15 votes
3 answers
12k views

What are the concerns and consequences of an overweight landing?

If a 777 ER has to immediately land after takeoff on a planned 14,594 km trip (in the case of a fire, e.g.), the landing will be executed with a very heavy aircraft. What are the major concerns of ...
Jonas G. Drange's user avatar
14 votes
1 answer
2k views

How is fuel stored and routed on a trijet with one engine at the tail?

This question pertains to trijets with two engines on the wings and one at the tail, like the Lockheed Tristar. It does not pertain to trijets with all engines at the tail, like the Tu-154. (And it ...
DrZ214's user avatar
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11 votes
3 answers
5k views

How do I determine the best altitude to fly for fuel economy?

If you fly low, air is dense so you can get more thrust from your engines, but you get more drag. On the other hand if you fly higher you have less drag but the output of engine decreases as well. So ...
shabby's user avatar
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6 votes
2 answers
5k views

Where can I find accurate information about fuel efficiency of Airbus vs. Boeing planes?

I am trying to understand the competitive positions of Airbus and Boeing's large civil aircrafts. I would imagine fuel efficiency would be very important to airline given its large component in the ...
Ben's user avatar
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5 votes
1 answer
7k views

Why do commercial airplanes smell like fuel smoke before take off?

Why does the cabin of commercial airplanes always smell like fuel smoke coming out from the internal ventilation a few minutes before taking off, I think when the pilot puts thrust into the engines ...
Alfonso Nishikawa's user avatar
46 votes
5 answers
19k views

Why are we still putting lead in our fuel?

Lead in gasoline for automobiles has been banned from nearly every corner of the world, with most bans dating from the nineties. Why are we still poisoning ourselves with lead in Avgas? I understand ...
falstro's user avatar
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19 votes
4 answers
10k views

Did any Boeing 787 operator achieve the 20% fuel efficiency improvement over the 767?

Is there any airline which are able to get the complete 20% fuel efficiency on their 787 with respect to 767 it is going to replace, as told by Boeing. I have read that one of the early customer like ...
NitinG's user avatar
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17 votes
4 answers
8k views

Where I can get historical jet fuels prices?

I would like to analyze jet fuels prices in 2014. Where can I get jet fuel prices for 2014, only in USA and Russia? As there are different types of fuels, it would be okay to get prices for one (...
LA_'s user avatar
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15 votes
3 answers
6k views

Why shouldn't you use HF radio while refueling?

FCOM limitations for many aircraft state: DO NOT USE HF RADIO WHILE REFUELING Why is this? I have heard from people that it's because most of the big airliners have a 'notch' antenna for HF; it's ...
Praveen Pillai's user avatar
14 votes
3 answers
6k views

Can a commercial airliner be too heavy to take off?

According to this question's answers, MTOW (or MTOM) is the Maximum Take Off Weight, which is everything up to and including trip fuel. Then there is one step above that, MRW, or Maximum Ramp Weight, ...
CGCampbell's user avatar
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11 votes
5 answers
2k views

Do aircraft use the majority of their fuel to overcome friction?

It was asserted (tangentially) in this question that airliners use most of their fuel to overcome frictional losses. Is that a true statement? If so, ...
FreeMan's user avatar
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11 votes
3 answers
29k views

How does the efficiency of a fixed wing compare to a rotary wing?

Is fixed wing more efficient than rotary wing? If yes, why is that?
user2174870's user avatar
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11 votes
5 answers
2k views

Where is the GA community at regarding fuel/engine types?

I promised myself that I would pursue my PPL if I successfully completed my phd. I'm now doing research about the when/how I should do this, and one of the big factors for me is that there's no point ...
William Walker III's user avatar
11 votes
2 answers
1k views

What are possible explanations for fuel being expelled in this video?

In another question, I asked about whether or not a fuel spill would be reportable or not. The answer was "no", because the aircraft was not in flight. What are the possible causes of the spill ...
Steve's user avatar
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10 votes
1 answer
3k views

Why do military aircraft use a different kind of aviation fuel?

Regular airliners use JET A-1 fuel. However, I've seen that military aircraft, i.e., Airforce or Navy; use a different kind of fuel called JP-N, where N is a number. What is the reason why this ...
Airman01's user avatar
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8 votes
3 answers
3k views

Can a Diesel Aircraft engine be run on Car Diesel?

What are the operational differences between normal diesel fuel used in cars and the Jet-A diesel type fuel used for some prop aircraft such as the Diamond DA62? I know that aircraft use Jet-A fuel, ...
user15172's user avatar
7 votes
1 answer
1k views

Does one-engine cruise consume less fuel than two-engine cruise?

Scenario 1. A two-engine airliner experiences rapid depressurization and makes an emergency descent to 10,000 ft, and diverts to the nearest airport. Scenario 2. The same two-engine airliner ...
lemonincider's user avatar
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7 votes
3 answers
1k views

Is it practical to use ground effect to extend range in an emergency?

Imagine a piston engine airplane (let's say a DC-3) flying at cruise speed and altitude over a calm sea, trying to reach an unreachable airstrip straight ahead, just above sea level. Fuel is very low ...
user avatar
6 votes
2 answers
3k views

How does a fuel density sensor work? (densitometer, cadensicon)

While some fuel volume sensors use ultrasonic measurements this answer to How is fuel mass measured in airliners? says: The FCOM lists the sensors involved in this measurement: The FQI system ...
uhoh's user avatar
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6 votes
2 answers
600 views

Would it be feasible for a typical passenger jet to carry along its own Oxidizer?

We know that many Space Shuttles / Rockets etc. carry their own oxidizer with them. This is partly because at the heights they operate the atmosphere is too rarefied to have enough oxygen to sustain ...
curious_cat's user avatar
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5 votes
2 answers
21k views

How much fuel do the new A320-Winglets burn vs. the B737-800?

Now that the new A320-Winglets have established themselves, I'm wondering if they have better fuel consumption than the B737-800? I was told that Boeing used to be marginally better. Is that still ...
Thunderstrike's user avatar
5 votes
3 answers
16k views

How is fuel weight calculated?

I was having a conversation concerning airplanes and the calculated fuel. We were having a conversation about the Airbus A380. Based on this site: http://www.modernairliners.com/airbus-a380/airbus-...
ronbravo's user avatar
4 votes
1 answer
906 views

What were the effects of the oil crises on the Concorde ticket prices?

One of the things that is considered to have greatly hampered Concorde's success were the dramatic oil price increases due to the 1973 oil crisis (the 1979 one surely didn't help either, but it was ...
Parker Lewis's user avatar
2 votes
3 answers
6k views

How Centre of Gravity (CG) is adjusted?

I've gone through the following questions on Stack Exchange and other few questions too: Why is managing CG (centre of gravity) important? How are the limits of the center of gravity chart ...
Lucky's user avatar
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-3 votes
3 answers
799 views

Would building an airport at 30,000 ft save money?

So... this would obviously cost a ton of money initially, but long-term, I believe the savings both environmentally and financially would be returned many times over. If a building can already be ...
Cloud's user avatar
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60 votes
5 answers
11k views

Why would a fighter drop fuel into a drone? [closed]

According to the BBC: A feed from a camera fitted under the fuselage of the surveillance drone shows a Russian SU-27 making two extremely close passes while releasing, what appears to be, fuel as it ...
Elerium115's user avatar