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-   -   Forward Acting Thrust (https://www.pprune.org/spectators-balcony-spotters-corner/486887-forward-acting-thrust.html)

donnlass 31st May 2012 20:57

Forward Acting Thrust
 
In How Airliners Fly it shows the workings of a jet engine and states:

"The fan, which is encased in a cowling, forces the compressed air backwards in the form of a jet, much in the form of a domestic electric fan. The engine itself experiences an equal and opposite force and this is the forward acting thrust which propels the aircraft".


If the thrust is coming out forward from the engine, how come the aircraft still flies forwards?:confused:

TURIN 31st May 2012 21:18

Newtons 3rd (I think) law of motion.

For every action there is an equal and opposite reaction.

Propel a mass of air rearwards and the resultant force (thrust) is forward.

Simples. :ok:

wiggy 31st May 2012 21:53


If the thrust is coming out forward from the engine, how come the aircraft still flies forwards?
Read "How Airliners Fly" again. What they are saying is the air expelled from the engine is going backwards, but the thrust (i.e. the force) produced by the engine is acting in a forwards direction, i.e. it's pushing the aircraft forwards.

WASALOADIE 31st May 2012 23:11

By pushing all that air through the engine rearwards, the engine sucks it way forwards

donnlass 1st Jun 2012 09:58

I will do:ok:

Thanks all for your patience and replies, I get it now:ok:

Lord Spandex Masher 1st Jun 2012 10:30

Although the action of producing thrust does produce a rearward force in the engine!

Load Toad 1st Jun 2012 11:29

Isn't there a bloody big vacuum in front of the engine...?

Lightning Mate 8th Jun 2012 16:10


Although the action of producing thrust does produce a rearward force in the
engine!
Not so I'm afraid.

The compressors and the diffuser section, amongst others, produce forward thrust. The turbine section produces a rearwards force. :)

Lightning Mate 8th Jun 2012 17:29

This should help your understanding.......

http://i636.photobucket.com/albums/u...tConverted.jpg

donnlass 8th Jun 2012 22:17

Should have a Reply With Quote Button on here but anyway:p


So the total forward gas load less the rearward gas load produces total forward thrust?

Lord Spandex Masher 8th Jun 2012 23:27


Although the action of producing thrust does produce a rearward force in the
engine!

Originally Posted by Lightning Mate (Post 7233926)
Not so I'm afraid.

The compressors and the diffuser section, amongst others, produce forward thrust. The turbine section produces a rearwards force. :)

So it does then...Unless I missed the bit where my turbine isn't in my engine;)

Lightning Mate 10th Jun 2012 15:18


So the total forward gas load less the rearward gas load produces total forward
thrust?
Well, if you think I am incorrect, check the Rolls Royce book, upon which my diagram above is based.

If you think it's wrong, then please feel free to put Rolls Royce on the right track!!!!

donnlass 10th Jun 2012 18:58

No I dont think you're wrong at all, am not qualified to think that:)


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