"TheOnelectronic" (theoneelectronic)
08/03/2013 at 16:39 • Filed to: planelopnik
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"TheOnelectronic" (theoneelectronic)
08/03/2013 at 16:39 • Filed to: planelopnik | 0
| 22 |
What purpose do these variable-diameter nozzles serve on (certain) jet aircraft? My first guess would be the thumb-on-the-hose method of controlling thrust, but my more reasonable guess would be temperature control. Any input?
I offer you Turbine Sounds as payment.
Victorious Secret
> TheOnelectronic
08/03/2013 at 16:41 |
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I think you got it, variably control the thrust. For more or less POWAAAAAH
POD
> TheOnelectronic
08/03/2013 at 16:45 |
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The intro to Top Gun has a nice shot of one in action. Right around the 2:30 mark.
vermillion-fire
> TheOnelectronic
08/03/2013 at 16:47 |
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referring to my (very) basic understanding of fluid dynamics, i think your correct as the smaller opening would increase flow-rate (thrust) through it.
BATC42
> TheOnelectronic
08/03/2013 at 16:51 |
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Refering to my engineering courses in fluid dynamics, I would say it is to change the speed of the airplane. Opening them would result in the plane going faster while while closing them would result in the plane goign slower.
But I wasn't really listening during this particular class so I could be wrong.
McMike
> TheOnelectronic
08/03/2013 at 16:58 |
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And here's a smarter one.
desertdog5051
> TheOnelectronic
08/03/2013 at 17:02 |
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Thrust vectoring.
https://en.wikipedia.org/wiki/Thrust_ve…
pdthedeuce
> desertdog5051
08/03/2013 at 17:06 |
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not always r
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pdthedeuce
> pdthedeuce
08/03/2013 at 17:06 |
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http://en.wikipedia.org/wiki/Propellin…
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desertdog5051
> pdthedeuce
08/03/2013 at 17:09 |
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Agree.
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TheOnelectronic
> desertdog5051
08/03/2013 at 17:17 |
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This particular image is of an F/A-18, which lacks thrust vectoring.
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TheOnelectronic
> POD
08/03/2013 at 17:20 |
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Ah, thank you. I understand now. It's basically shaped to evacuate the exhaust gasses quickly and efficiently, and the variable-geometry ones are used particularly for Afterburner-equipped planes, where it needs to adapt to the different something something explosions.
ttyymmnn
> TheOnelectronic
08/03/2013 at 17:23 |
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The "turkey feathers" expand to allow for extra exhaust emissions when an aircraft is traveling at high speed. As more air and fuel is sucked into the engine to allow the aircraft to travel faster so must the "turkey feather" exhaust panels expand to allow for the extra exhaust emissions. Otherwise the engine exhaust pressure would build up and the engine would blow. This allows the engine to optimize the inlet/outlet pressure and provides smooth operation from idle to afterburner in all flight modes.
I don't believe the F-18 has thrust vectoring per se. The engines aren't a mechanism to steer the jet as in the F-22. However, there may be some vectoring capabilities, they just aren't built in as a design element.
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TheOnelectronic
> ttyymmnn
08/03/2013 at 17:27 |
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"Turkey feathers" haha, now I'll never forget that.
I'm also fairly sure the base F/A-18 here doesn't have vectoring, though I'm sure somewhere there's someone who dreamed up a variant that includes it.
Yep, although using the redneck-by-nasa-standards method.
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POD
> TheOnelectronic
08/03/2013 at 17:28 |
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Yup, the F-16 (the popular jet fighter in Top Gun) used an Iris type nozzle to smooth exhaust gas airflow. Really cool technology for something that anyone with a garden hose and a high pressure nozzle can simulate.
For fun, try turning your garden spigot all the way up with a high pressure nozzle attached. Then adjust the nozzle for the longest smoothest water flow. Now back the spigot off to 1/3 or 1/4 open and readjust the high pressure nozzle to get the smoothest flow. It'll give you a good real world demonstration. That's not an Iris type, but it's still a fun little experiment.
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ttyymmnn
> TheOnelectronic
08/03/2013 at 17:32 |
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That's the NASA Thrust Vectoring High Alpha Research Vehicle. Those thrust vectoring attachments are definitely after-market. You can read all about it here . Bring your slide rule.
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ttyymmnn
> TheOnelectronic
08/03/2013 at 17:36 |
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See 7:28. This is an engine from an F-104.
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TheOnelectronic
> ttyymmnn
08/03/2013 at 17:36 |
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Part of me thinks that style is really cool. It's got a sort of... I don't want to say steampunk, but it's got a similar sort of low-tech-high-tech aesthetic. There's a word for this, I know. Cobbled-together?
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ttyymmnn
> TheOnelectronic
08/03/2013 at 17:38 |
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Sort of like a home built hot rod. Bolt it on and go racing.
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ttyymmnn
> McMike
08/03/2013 at 17:42 |
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Interesting soundtrack for a jet engine test....
You can tell a Finn but you can't tell him much
> POD
08/03/2013 at 18:03 |
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That would be the F-14 Tomcat in Top Gun. The F-16 is a single engine Air Force fighter.
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POD
> You can tell a Finn but you can't tell him much
08/03/2013 at 18:05 |
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Oh Crap, yes, you're right. My bad. The F-16 used an Iris Nozzle as well, but ya, not in Top Gun.
Rookie mistake, back to the dugout with me.
Destructive Tester
> desertdog5051
08/03/2013 at 18:35 |
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That's a negative Ghostrider, currently the only examples of vectored thrust in (or sort of in) the US arsenal are the AV-8B Harrier, the F-22 and F-35. The explanation of exhaust pressure regulation pretty-much nailed its purpose.
In spite of its deficiencies, of which there are many, an F-22 being flown hard is a sight to behold...