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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
25 votes

Will all turbine blades stop moving in the event of a emergency shutdown?

No. Assuming the rotating bits are undamaged, both the engine core and the fan section will windmill in the airflow. The benefit of stopping the engine spools is not worth the complexity, cost, weight ...
John K's user avatar
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24 votes
Accepted

Is starting a jet engine without ground support possible?

Modern jet transport category aircraft have APUs and they will be running if no engines are. Batteries on jets do not work very long with all electrical buses energized and the first thing you do ...
casey's user avatar
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24 votes
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Why do large turbofans generally have many more LP turbine stages than HP turbine stages?

Because the LP turbine extracts power for the fan, which requires the most power. The HP and IP turbine only extract power for their connected compressors - the LP turbine extracts power for the fan ...
Koyovis's user avatar
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24 votes
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Is the compressor required on jet engines? Can air be rammed into the turbine?

Your questions At what point (if any) does air stop getting sucked into the turbine and is just getting rammed in? On a CFM56-7B engine (Boeing 737 NG) pressure is provided by the fan, the low ...
mins's user avatar
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24 votes
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What does the small needle + scale on this turboprop's N1 gauges indicate?

It duplicates the percent graduations in the large dial but at a finer resolution, with one percent increments. It's just to make the individual percent graduations easier to discern at a glance ...
John K's user avatar
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22 votes
Accepted

Is it possible to drive a prop directly from a jet engine without a gearbox?

As a side comment, there is a type of engine researched in the 80's/90's, but never marketed, where an unducted fan is driven directly by the turbine shaft without a gearbox: The propfan. It's close ...
mins's user avatar
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21 votes
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What are these engine inlet devices used for?

The first photo shows the engine air intake screen. Its basically a screen to prevent FOD ingestion, as you noted. From CH-47 Theory of Operations: Engine Inlet Screens An engine inlet screen which ...
aeroalias's user avatar
  • 100k
19 votes
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Compressor-Turbine: Why a shaft and not kind of a "rotating drum"?

There are a few very practical reasons why turbine engines use inner shafts/spools. First, jet engine spools are very high speed rotating parts, this means they are subjected to high amounts of ...
OSUZorba's user avatar
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18 votes

Has anyone burned hydrogen in a gas turbine?

For fuels intended for use in aircraft, the key performance parameter is the energy density of the fuel: how much potential work is stored in how many liters of stuff. High energy density means the ...
niels nielsen's user avatar
18 votes

Would it be possible to put wind turbines alongside runways that are driven by the exhaust of planes?

No, there's no practical benefit to putting wind turbines alongside runways and plenty of drawbacks. Airplane engines and propellers direct their thrust straight back, so the only logical place to put ...
GdD's user avatar
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18 votes
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What originally spins the intake fan when the engine is started?

Most turbofans have a 2 spool design: The fan and low pressure compressor (LPC) are powered by the low pressure turbine (LPT) and rotate at a speed called N1. The high pressure compressor (HPC) is ...
Bianfable's user avatar
  • 55.5k
17 votes

How hot do internal parts of jet engine get?

This parameter is called Turbine Inlet Temperature (TIT) Turbine Inlet Temperature (TIT) is the temperature of the combustion chamber exhaust gases as they enter the turbine unit. The gas ...
user3528438's user avatar
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17 votes
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How much water does it take to cause a flameout in a modern turbine engine?

Turbofans are the best at taking in a large volume of water. Almost all of it stays in the bypass stream, as it's deflected away from and around the core's inlet. Most turbofans are designed to Part ...
Therac's user avatar
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16 votes

Are there Hybrid Electric-Combustion Turbine Engines where only the compressor is electric driven?

I don't know if such an engine exists, but I can assure you that it wouldn't be a good idea. The reason is that you would be introducing multiple additional failure modes, each of which would result ...
Michael Hall's user avatar
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16 votes
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How exactly is the free shaft part of a gas turbines controlled?

The free turbine is literally just a windmill that generates torque when the wind blows on it. You could actually just stick it outside the engine itself behind the tailpipe and it would do the job, ...
John K's user avatar
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15 votes
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is boundary-layer jet-turbine a scam?

In short, they are both scams that fall heavily into the category of Not Even Wrong or cargo cult science.Tesla's work is sadly a great favourite of conspiracy theorists who do not have the technical ...
KuangGradeMark11's user avatar
15 votes

What does the small needle + scale on this turboprop's N1 gauges indicate?

If the engine is at 95% RPM, the large needle will point halfway between the "90" and the "100" indication on the outer scale, and the needle on the small dial will point to the &...
Ralph J's user avatar
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15 votes

What originally spins the intake fan when the engine is started?

There are several ways this is done. You can use an electric motor running off a battery to spin up the jet engine, or you can use a big fan to blow air into the air inlet of the engine, or do the ...
niels nielsen's user avatar
14 votes

Why can't we extract more from exhaust gases in gas turbines?

It can be done, but the better specific fuel consumption does not compensate for the extra weight. We all know that aero engines have to be as light as possible. In land, stationary installations, ...
xxavier's user avatar
  • 11.1k
14 votes

Are there Hybrid Electric-Combustion Turbine Engines where only the compressor is electric driven?

No, such engines do not exist, as is implied in the question already: I can't tell if this idea is good or simply bad, nor I could find any examples of such engine. Pic above is an own photo, used ...
Koyovis's user avatar
  • 61.6k
13 votes

Compressor-Turbine: Why a shaft and not kind of a "rotating drum"?

A rotating drum will have a higher inertia. When the pilot commands a thrust increase, spooling up the drum will take longer than spooling up a shaft. Also, a big drum is harder to balance well than a ...
Peter Kämpf's user avatar
13 votes
Accepted

Which are typical rpm values for aeronautical turbines?

First of all: There is not one single speed on many aircraft engines. Big propeller engines have a reduction gearbox so the propeller runs at a lower speed than the core engine, and multi-spool ...
Peter Kämpf's user avatar
13 votes

What engine are these fan blades from?

Turbine Blade The turbine blade (part number 1475M35P01) is from the High Pressure Turbine (HPT) a CFM56-3 according to this ATSB report on performance testing of the engine. The report contains ...
Notts90's user avatar
  • 3,559
13 votes

Why aren’t diesel piston engines used on aircraft like the Saab 340 or L-410?

There are many reasons but Ill address your points directly first Engine itself is significantly cheaper This is only true for non aviation engines. Even if you were to obtain a type certification ...
Dave's user avatar
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12 votes
Accepted

How is the central hub / shaft casing of a two-spool jet engine assembled?

The first thing to know when designing jet engines, is everything leaks. But the OD of the engine core is generally pretty tight. This is achieved using large solid structural pieces, for example the ...
OSUZorba's user avatar
  • 2,639
12 votes

Why would a jet engine use cannular combustors if the annular design is superior?

Single combustor cans are simpler to develop. To get the ignition and combustion process right in an annular combustor is quite a challenge. When the first jet engines were developed, Junkers decided ...
Peter Kämpf's user avatar
12 votes
Accepted

At what point is a turbine powered ducted propeller considered a turbofan?

tl;dr They're pretty much all considered turbofans with a few exceptions from the '70s such as this experimental Britten-Norman Islander. They key difference is a prop can be considered a separate ...
Notts90's user avatar
  • 3,559
12 votes

What's that rattling noise from parked jets?

It's fan or compressor blades rattling loosely in their blade roots as the engines windmill in the breeze. The blades are attached to a hub or disc, and the retaining systems for the blades have to ...
John K's user avatar
  • 130k

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