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Old Mar 24, 2013, 07:24 PM
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Random Edf idea! Turbofan edf...

Would it be possible to have a turbo fan edf? My idea is to have a regular edf with a larger fan at the front of the unit, then with another duct around the whole thing. Just like a real turbofan, now I understand that the difference between real turbines and edfs is large, but what do you think would happen? Please express you thoughts.
Thanks, Nick
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Old Mar 24, 2013, 08:42 PM
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Anyone?
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Old Mar 24, 2013, 08:48 PM
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now I understand that the difference between real turbines and edfs is large,
Obviously you don't.
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Old Mar 24, 2013, 08:48 PM
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There would be no benifit. Just run the larger fan.
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Old Mar 24, 2013, 08:50 PM
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Sorry If I sound stupid, but why not?
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Old Mar 24, 2013, 08:55 PM
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Aren't there some alloy fans that have a smaller fan section in the middle? Just for motor cooling but sounds like the same idea HS is describing.

Come to think of it, Most EDF's are very similar to turbofans producing the majority of thrust with the "large front fan". The only difference is they don't have any faster turning high speed core. Only one spool instead of several.
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Old Mar 25, 2013, 01:14 AM
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Originally Posted by HiddenSky View Post
Sorry If I sound stupid, but why not?
In the turbofan you burn fuel creating heat, alot of heat. Heat is energy, which you never get from the EDF.

These two units produce about the same thrust but with very diffrent size. The EDF is big and produces airflow at low speed while the turbine is small and by adding fuel increases the energy alot.(actually the EDF only does 1/2 of the
turbine)



With a turbine you can snag this huge energy flow with a 2:nd stage turbine and create a turboshaft unit, but with en EDF the best you can do is to unscrew the motor and use it with a gearbox and propeller :-)



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Old Mar 25, 2013, 03:15 AM
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There was someone early last year that posted a vid of exactly what you're talking about but the fan was attached to a turbo prop...

Wish I could find the vid...

My understand it was really efficient compared to other micro turbines or picked up a lot of static thrust, there was some spec increase that was notable

regards
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Old Mar 25, 2013, 03:18 AM
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Originally Posted by 4stripes View Post
Aren't there some alloy fans that have a smaller fan section in the middle? Just for motor cooling but sounds like the same idea HS is describing.

Come to think of it, Most EDF's are very similar to turbofans producing the majority of thrust with the "large front fan". The only difference is they don't have any faster turning high speed core. Only one spool instead of several.
Yeap, EDFs would be a large percentage bypass or 100% technically IINM
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Old Mar 25, 2013, 03:28 AM
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Erh, why would anyone attach an EDF to a turbo prop? That sounds like a terrible idea. Electric motors w/gearbox like henke says is a much more efficient solution.

Maybe you're thinking of this?

http://www.rcgroups.com/forums/showthread.php?t=1476513

Hiden Sky, there are a lot of things in this hobby that will work. Your idea would work fine. But there would be no benefit to it other then 'bling' factor and chances are you will be losing efficiency. You would also have to try and explain your idea to everyone that asks 'why' . All you're really doing is spinning two different sized fans off one motor.
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Old Mar 25, 2013, 03:36 AM
310mph Kolibri T25 Swist
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Originally Posted by SlowBarless View Post
Erh, why would anyone attach an EDF to a turbo prop?
EDIT, saw your link to late

That's either a typo or a big diffrence that actually makes sense! ...and have been done with great success. Very good solution for the slower airplanes that don't need the efflux of the turbine.



Turbofan Engine for RC Model Aircraft (4 min 28 sec)
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Old Mar 25, 2013, 04:29 AM
I am actually really slow
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Originally Posted by henke View Post
EDIT, saw your link to late

That's either a typo or a big diffrence that actually makes sense! ...and have been done with great success. Very good solution for the slower airplanes that don't need the efflux of the turbine.



http://www.youtube.com/watch?v=fIiuSHSzf_Q
Whoops, I could have worded that better

I meant replacing the turbine stage of a turbo prop with an EDF is a strange idea.

You're basically using one size fan, to drive another fan of a similar size to turn a gearbox? Why? You're better off taking the fans out of the equation and running the gearbox direct.

To me these threads are getting kinda silly. It reminds me of the time I saw an electric motor which had pistons on it to give it an internal combustion kind of look. Completely stupid, no benefit at all. Just effect.
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Old Mar 25, 2013, 04:45 AM
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The turbofan is just a DF where you use a turbine engine to produce the power. This gives the turbine a better performance.

The princip in the EDF is the same..... we just use an electric motor and convert all of the power to run the fan.
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Old Mar 25, 2013, 05:15 AM
310mph Kolibri T25 Swist
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This gives the turbine a better performance.
Well, it gives the turbine another envelope to work in :-)
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Old Mar 25, 2013, 07:11 AM
I am actually really slow
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Originally Posted by jweber009 View Post
This gives the turbine a better performance.
.
I wouldn't say better. It depends on what you want to do with the engine. For airlines and most supersonic jets a low or high bypass turbofan would probably be more suited then a turbojet. But turbojets still have a place, in all our turbine models for example (:
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