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Old Aug 05, 2006, 06:12 PM
Trampling out the vintage
Joined Feb 2002
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Power for an EDF HO 229?

There are some folks over at RCScalebuilder who are building a Horten 229, 66" span. http://www.rcscalebuilder.com/forum/...?TID=6750&PN=1
I would guess the weight before power system or battery to be two lbs. or so.

This of course is a twin; right now the dimensions of each duct are
Length: 18.68"
Inlet diameter: 2.75"
Exhaust diameter: 2.46"

Any suggestions on an EDF power system? I have not previously indulged in EDF, but this would be very tempting.
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Old Aug 06, 2006, 08:02 PM
Trampling out the vintage
Joined Feb 2002
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Perhaps I can ask the question a different way. Is there any technical source that describes the parameters for EDF duct width vs length? The scale intake/outlets on the HO 229 appear to be long and skinny compared to typical EDF units. I am concerned we cannot achieve a scale look or proportion on the ducting.
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Old Aug 06, 2006, 08:13 PM
EDF Jet Jam 2015 , May 28-31
Kevin Cox's Avatar
St. Louis Intl, Missouri, United States
Joined Jan 1997
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Greg,

You should use the search function. But I will answer a few questions based on what works for me.

Looking at your project, ducting length isn't a problem. You will probably need to mount the fans more forward in your model.

The width is determined by the FSA (fan swept area). The intake FSA should be about 100% and the outlet of 90%. You can squash the outlets and inlets as long as you maintain a gradual change to and from the fan.

I hope this helps.
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Old Aug 06, 2006, 09:24 PM
Trampling out the vintage
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Thanks.
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Old Aug 07, 2006, 04:36 PM
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WURPFEL's Avatar
Swiss
Joined Jan 2004
91 Posts
Interessting project!

based on the originaljetDIA of 600mm I kooked for an thiny EDF and found the EDF40 very pleasent.. my HO9 is much smaller than yours it`s very difficult to find a suitable taller EDF, maybe it`s works only scale in a superlight-setup aka slowflyer.
badly the long and small EDFs with huge power arn`t very good performant systems, they have great losses

maybe the bonsai-miniturbines from Lanbert are a option for you

look at the proto build out of a 3mm depron sheet to check the handling and for indooruse.
this two EDF40 (lil black things on top) are scale in dimensions of the span: the HO9 was a big bird!!

now the plane is under construction with a MH74 profile, that`s looks nearly like the original horten-one.


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Old Aug 07, 2006, 05:49 PM
AKA Terry Till
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Alexandria, VA
Joined Apr 2002
1,541 Posts
Greg,
This may prove useful:
http://www.wattflyer.com/forums/showthread.php?t=6847

Why re-invent the wheel?
Video near end of thread.

Terry
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Old Aug 07, 2006, 08:10 PM
Trampling out the vintage
Joined Feb 2002
1,893 Posts
Quote:
Originally Posted by ex-racr
Why re-invent the wheel?
Terry that's the definition of modeling - we do it again. Smaller.

Thanks for the link and video. We are intending this to be near-perfect scale; that guy's model is pretty good but not quite scale.

From all accounts this will be a deceptively challenging model. The airfoil and canopy have to be perfect or it likely won't fly. However, the lines are stunning and we feel it's worth a try...

Thanks to you all for your help.
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Old Aug 07, 2006, 10:49 PM
Electric Coolhunter
Thomas B's Avatar
United States, TX, Fort Worth
Joined Jun 2000
14,639 Posts
Your exhaust and inlet sizes are near what is needed for a WeMoTec Minifan 480 setup. That is probably the most used fan on this forum.

A search on Minfan 480 setups will yield tons of information.

With two of them in a 66" span Ho-229, I would go a little mild, with something like Mega 16/15/3 on 3S lipos to start with. 16/15/2 if you wnt more power on 3S.

Might be tough to get it to balance, as it is hard to get the batteries close enough to the front of the nose to help much.

The fans need to be placed as far forward as possible.
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Old Aug 07, 2006, 11:44 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
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Hi Greg

Slightly different suggestion- the Wemo 505 rather than the Minifan- the fan is a bit smaller- think it will take the inlet and outlets you've got a bit easier. Ken at K + A makes a nice liner for it that's 68 mm OD. If you really need a few extra mm smaller, the Vasa 65 fan would work- but it's terribly delicate unless you really support the housing well- which come to think of it- this airplane might do quite well.

Some of the options depend on whether you want lowest weight or not-

Lowest weight- the Vasa 65 on a Medusa 028-32-3400 (think that's it)- should pull about 250 watts on 3s. around 4 oz

In the Wemo 505- the above motor will do about 300 watts on a hot 3s pack. Both setups worked fine in a 1.5lb F-86.

More watts- Wemo 505 with a Mega 3 turn on 4s. 350 watts on wimpy 4s, 450 watts on a hotter pack. Around 5.5 oz.

Figure the 450 watt setups weigh around 1 lb- the 300 watt setups will be closer to 12 oz or so.

Pay lots of attention to your inlet- if you can't come up with a nicely rounded inlet- add lots more watts.

In flying EDFs don't go less than 150 watts/lb- 200 watts/lb is kinda nice. If you want speed- go for more watts- the highest I've hit is around 275/lb.

HTH

Sam
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Old Aug 08, 2006, 08:55 PM
Trampling out the vintage
Joined Feb 2002
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Again many thanks for the comments. Those of us on this project are scale modelers first, and real newbies to EDF. Your comments are invaluable. I will check out all the alternives mentioned.

With the fans forward and a bit of a nose on this I am optomistic about the CG.
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