26
votes
Accepted
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 ...
- 71k
24
votes
Accepted
What is missing from a non-afterburning engine to prohibit the use of afterburning?
The afterburner, of course.
In simplest sense, the afterburner is just an extension attached to the engine where the fuel is dumped into the exhaust, resulting in an inefficient but huge increase in ...
- 100k
22
votes
Accepted
Why do military jets seem to always take off using the afterburner?
Military aircraft takeoff with afterburner when it is safer to do so with an exception- carrier pilots always light their cans while taking off (and also when the pilot wants to show off, but lets ...
- 100k
14
votes
Why would a fighter use the afterburner and air brakes at the same time?
While the pictures above are most likely a result of the reason posited by ymb1 (showing off max blast while staying subsonic for the crowd), using afterburner with speedbrakes to reduce weight is a ...
- 141
13
votes
How does a jet engine burn fuel when it is not on an afterburner?
Another NASA article shows you the diagram you need.
You can see the two places fuel can be injected, before and after the turbine. As you say
there are two separate phases to add fuel to airstream
- 2,154
12
votes
Accepted
Are warbirds allowed to use afterburners?
No, no restrictions on using an afterburner. There are a few F104 Starfighters on the civil registration that must use the afterburner to take off.
However, most countries forbid supersonic flight by ...
- 8,717
10
votes
Is it possible to have an afterburner in a turbofan with bypass ratio greater than 1:1?
Can you add reheat to a high bypass turbofan engine? Sure. The real question is what is the purpose for doing so?
The bypass ratio of a turbofan is based largely on its operation regime. Turbojets ...
- 72.8k
10
votes
Are warbirds allowed to use afterburners?
A friend has a demilitarized warbird. The full propulsion system remains intact. Sometimes, in full view of the FAA, at airshows, he will light the afterburner. I know of no regulation which ...
- 17.7k
10
votes
What is an afterburner and how long can a jet fly on afterburner?
I flew B-1B's for 7 years. I've also had flights in F-15s and F-16s. The B-1 has 4 afterburners, but a lot more gas than the fighters, so I rarely had to stay out of burner due to fuel. There's ...
- 101
10
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Why do Western fighters' afterburner glow is reddish orange while Eastern Bloc fighters' is blue?
It all depends. I don’t think there’s a distinctive color between the two. I would submit that the photos of the Flanker may be in a early stage of the afterburners lighting versus the photos of the ...
- 72.8k
9
votes
Will afterburner work at settings less than full dry thrust?
Afterbuner simply injects fuel directly into the jet pipe (i.e. beyond the turbine) in order to greatly increase thrust. The way throttle levers are normally set up, afterburner is engaged once the ...
- 2,882
8
votes
Is there an aircraft that can go supersonic at sea level without using afterburner?
According to Wikipedia, the BAC TSR-2 was capable of supercruise (no reheat) at Mach 1.1 at 200 feet (~60 m) altitude. The TSR-2 first flew in 1964. The English Electric Lightning had demonstrated ...
- 17k
8
votes
How does a jet engine burn fuel when it is not on an afterburner?
The basic answer is yes. Fuel is burned in the main section to make thrust (and drive a fan in that kind of engine), and keep the compression/combustion cycle going, and to work properly (not melt ...
- 126k
7
votes
Do afterburners use excessive amounts of fuel?
Yes the specific fuel consumption of the afterburner, lbs of fuel used per lb of thrust, is much higher than the core engine. This is because the fuel is being added to a part of the engine where the ...
- 126k
7
votes
Accepted
How does the Pratt & Whitney F119 achieve its features?
The afterburner is aft of the gas core of the engine in the jet pipe and bypass air from the fan would have already been mixed with the exhaust gases from the core prior to passing through the ...
- 72.8k
6
votes
Accepted
What effect would a afterburner have on the compressor if the nozzle outlet is not increased?
Yes, when the AB is lit, the nozzle needs to be opened, because the increase in exhaust temperature causes a decrease in density (pressure remains about the same), and so the same mass flow needs a ...
- 4,463
6
votes
How does afterburning not affect upstream air in the engine?
The afterburner will always affect the upstream flow, as it is subsonic throughout the entire engine (remember, hot air has a higher speed of sound). A properly designed afterburner should therefore ...
- 12.9k
5
votes
Accepted
How does an aircraft distribute fuel equally between powering the turbines on the engine and injecting it into the afterburner?
The aircraft fuel system does not distribute fuel equally among the afterburner and the engine's core (i.e. the compressor-combustion chamber-turbine part). It distributes fuel in such a way that the ...
- 100k
5
votes
Accepted
Why afterburner fuel nozzles aren't creating a lot of drag during normal operation?
I don't believe that those are the fuel nozzles (more correctly called the fuel spray bars). Here's a schematic of a turbojet with and without afterburner.
image from aerospaceweb.org
The fuel spray ...
- 106
4
votes
Accepted
Are afterburners required to be engaged during catapult launch?
The short answer is very much "no" -- afterburners are not at all required to launch from an aircraft carrier. Longer answer: Fred Larson's comment is correct: it really depends. Ultimately a given ...
- 1,107
4
votes
Accepted
Why are F-15s usually taking off with afterburners?
To be sure to not use more runway than available.
It is also good to have runway to spare in case take-off has to be aborted.
Look at this image as an example from another fighter. Notice the two X-...
- 1,731
4
votes
How does afterburning not affect upstream air in the engine?
It's pretty simple. When in reheat, the core engine is already running at maximum thrust, so the inertia of the mass flow out the turbine section is such that the reheated air has nowhere else to go ...
- 126k
3
votes
Do afterburners use excessive amounts of fuel?
If you look at it in terms of thrust vs fuel flow, then yes, they're very inefficient.
However, if you just look at the amount of fuel burnt to get an interceptor from the runway to 30,000ft, then ...
- 3,353
3
votes
Are afterburners required to be engaged during catapult launch?
It depends on the aircraft type, loadout, fuel aboard, required endspeed, weather and winds, etc. Some jet aircraft or carriers e.g. the S3 Viking, A-6/EA-6B, A-7 etc. did not use engines equipped ...
- 72.8k
3
votes
How can one achieve supersonic cruise capabilities without afterburners?
A normal jet engine has subsonic flow throughout. This avoids shock problems such as choking or excessive acoustic noise.
A conventional afterburner accelerates the exhaust flow to supersonic speed, ...
- 6,932
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