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Old Oct 29, 2008, 03:59 PM
Claus at Area 52
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copenhagen Denmark
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Mini-HowTo
ducts for EDF's

this is ment to be a short how to make a duct or control a duct in a model and what to expect from its performance.

This is not for one specific fan ... it goes for all of the 70 mm dia fans.
The ram airspeed tells the accelleration of the air from before the intake lips and down the ducting just by the area change in the tube.
you can read it the other way around as well ... high numbers means bigger resistence
But at any time rememer low speed are costs less to handle than high speed air... and do not change direction with more than 6 degrees.

Claus at area 52
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Old Oct 29, 2008, 11:03 PM
Cut the yellow wire
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Good info Claus.

Mike
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Old Oct 30, 2008, 07:02 AM
EDF rules... :)
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What fluid dynamics program did you use to come up with your assumptions?

Eric B.
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Old Oct 30, 2008, 07:45 AM
Claus at Area 52
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You are welcome to correct Eric..
But most of it is from learning the hard way in real life.
One could use a lot of formula's but i have tried to make as simple as possible, for most people to understand area ruled ducting without throuble, and the benefits from that.
Claus
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Old Oct 30, 2008, 07:52 AM
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Sebastian Fla
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Thank you Claus. Most helpful.

In the 5th illustration, did you intend to have a gap between the end of the taper in the aft duct and the beginning of the parallel section of aft duct. I know they do that (intentionally leave a gap) for a turbine.

Regards and thanks in advance,

Leonard
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Old Oct 30, 2008, 07:59 AM
Claus at Area 52
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copenhagen Denmark
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the gap they have in turbine powered model is like an injector taking air from the inside of the plane, sorts of cooling the turbines outside.
on my # 5 it is just to show that the it will not desturb the flow, wether you have just the necked down exhaust or you ad a food of streight tube, as long as it is with a smooth surface inside.
Claus
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Old Oct 30, 2008, 11:59 AM
BladeRunner
Indianapolis, indiana
Joined Dec 2007
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11 Bladed Beast form Indiana

Hi Claus,

My name is Fred Baldwin, and I am the designer of the Dyn-E-Max fan unit. I would be curious to see some of your design thoughts on 127 mm fan docking systems.

Fred.
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Old Oct 30, 2008, 12:07 PM
deltas are cool
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Tehachapi ,CA.
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Claus what are your thoughts on a duct as i have in the draken where the inlet duct tapers in onto the motor hub ...covering the spinner?
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Old Oct 30, 2008, 12:13 PM
EDF rules... :)
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Hi Claus,

Just curious, I thought you had been using one. The only thing I would add is there is a flow stagnation point at the entry lip on all the versions even the ones that do not have one drawn in.

Eric B.
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Old Oct 30, 2008, 12:37 PM
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Excellant work Claus! This needed to be done. The drawings speak very loudly.

Ron
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Old Oct 30, 2008, 12:54 PM
Claus at Area 52
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Air Sally.
what goes on in the Draken duct is more or less like the # 4 solution.
the front of the jet screamer will work very much like the nosecone i have put in there
Claus
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Old Oct 30, 2008, 01:00 PM
Claus at Area 52
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Eric..
If you take a look at the top half of every drawing it is there with a little line.
but you are right ... should have been on the bottom too.
Claus.
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Old Oct 30, 2008, 01:01 PM
Claus at Area 52
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Ron.
that was my intention ...
and to get rid of cheater holes in every model....i just hate them ..
Claus
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Old Oct 30, 2008, 05:04 PM
EDF rules... :)
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Claus,

The pictorials are very good, I have tried soem of them since you and Klaus posted the first of the area ruled pics and they are not far off if any from what would be experienced. Thanks for posting.

Eric B.

I agree with your post about having cheaters, they arent needed.
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Last edited by AirX; Oct 30, 2008 at 05:05 PM. Reason: Added Comment
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Old May 26, 2009, 11:38 AM
ParkScaleModels
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United States, PA, Loganville
Joined Feb 2002
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Claus,

I'm working on a EDF project and I am concerned with the ducting design. Should the intake be equal to or greater than the FSA? Your illustrations are great for the concept (which I understand, thanks!), but there's no indication of how the intake diameters you have drawn relate to the FSA.

Zeke
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