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Old Mar 07, 2014, 04:37 AM
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Joined Feb 2013
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Dual 90mm Fans

Hi Guys

Anyone know of where i could get dual 90mm Fans with 4KG of thrust each to total 8KG. One unit must run in the opposite direction (Counter rotation).

I want to run the set-up on 6S per side.

I am looking into building one of these amazing looking Rafales..

http://www.therccustomjets.cz/userFiles/img_1148.jpg

Cheers for any tips...
Martin
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Old Mar 07, 2014, 08:54 AM
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Larry Dudeck's Avatar
Williamsville, NY, USA
Joined Sep 2000
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Might be tough finding counter-rotating fans. But I wouldn't let that stop me. After building nine twin EDF's, I can not think of a single instance where asymmetric thrust was an issue.

No asymmetry issues were noted on three A10's, two F89's and four Twin Biz Jets.
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Old Mar 07, 2014, 08:59 AM
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Wow. Really so on all your dual EDF models, you noted no problems with both Fans rotating in the same direction ?...
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Old Mar 07, 2014, 09:09 AM
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4stripes's Avatar
Canada, ON, Burlington
Joined Jan 2009
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Never was an issue with my ME262 or Windrider 737(built for a friend).
CR fans may be helpful if you are planning a model capable of hovering.
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Old Mar 07, 2014, 10:17 AM
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tom bacsanyi's Avatar
farmington hills mi.
Joined Sep 2006
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On propeller planes there is rotation in the prop wash and resulting torque applied to the airframe. The stators in a typical edf remove the rotation. No rotation, no torque.
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Old Mar 07, 2014, 10:32 AM
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United States, MN, Hermantown
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I thought I had seen that kit before--
http://www.rcgroups.com/forums/showthread.php?t=1727001

pekos's has some fine designs, for sure.

Quote:
I want to run the set-up on 6S per side.

I don't think 6s will cut it.
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Old Mar 07, 2014, 04:45 PM
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United States, CA, Chula Vista
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They are correct, no issues with same rotation twin fan setup. However, Hobby King sells them in their international warehouse:

http://www.hobbyking.com/hobbyking/s...Rotation_.html

You may find it domestically, but this may be suited for your requirements.
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Old Mar 07, 2014, 05:24 PM
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United States, MN, Hermantown
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Right in the first post of his build thread, he says this
Quote:
I plan for this plane 2x 90mm EDF from VASA and 12s Lipoly. Weight 7500gr. and thrust together 8500-9000 gr.
This one big plane. L= 75" ( 1/8th scale) So wingspan should be around 53" .
His estimated AUW is 17.6 lb. 8500-9000 gr of thrust is approx 18-20 lbs..


He is also running his VASA fans on 12s--ea. No running 6S per side here I'm afraid
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Old Mar 08, 2014, 02:58 PM
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Herb's Avatar
Irvine, Calif USA
Joined Feb 1999
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Quote:
Originally Posted by Martin Turner View Post
... Anyone know of where i could get dual 90mm Fans with 4KG of thrust each to total 8KG. One unit must run in the opposite direction (Counter rotation).... Martin
Hi Martin I've been flying two Rafales with twin 90's for several years now ... no issues whatsoever with two fans spinning the same way You can see several video of my Rafales on youtube under Aeronaut Rafale.

Seems like a nice project, when set up right the Rafale is a sweet flier, good luck with it !

.
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Old Mar 09, 2014, 01:18 AM
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FrankW's Avatar
Portland Intl, Oregon, United States
Joined Dec 2002
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Counter rotating edfs sounds like a gimmick to me. Heck, I don't even use counter rotating set ups on my twin prop jobs. You'll be fine with two EDFs going the same direction, but you won't be so fine with only 6s on each fan with that large of a plane.

-Frank
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Old Mar 09, 2014, 01:41 AM
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Thanks for your replies. Very Useful.

So from what I heard, that twin 90mm Rafale is being converted to run on a single 120mm fan, as there was problems with the dual set-up. I am guessing that weight vs power was the problem.

I don't think the Peko chap is ready to ship any of his kits yet.

So I am looking for a Jet Kit - I want to build something!

Anyone know of proven plans and ideally a short wood kit for a large 120mm Fan EDF Jet ?. Not confident enough to scratch build a big jet.

PS. Great looking Model Herb -
What power set-up?
What size ?
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Old Mar 09, 2014, 01:34 PM
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Quote:
Originally Posted by Martin Turner View Post
... So from what I heard, that twin 90mm Rafale is being converted to run on a single 120mm fan, as there was problems with the dual set-up. I am guessing that weight vs power was the problem. ...
Hi Martin, If you do the math correctly the Twin 90mm fan setup will fly just as well (if not better) than the single 120mm.

And cost-wise there will be no difference, in fact the Twin 90mm can be cheaper and just as efficient.

The main reason is largely the avaliability of relatively inexpensive yet very reliable ESCs (eg HW or YEP) and 90mm fan inrunner 36-39mm motors (Het, Neu, Tenshock, Leopard etc).

Quote:
Originally Posted by Martin Turner View Post
... Great looking Model Herb - What power set-up? What size ?
The two Rafales pictured above are both all-molded twin 90mm Aeronaut kits:

http://www.rcgroups.com/forums/showt...=343257&pp=100

http://www.rcgroups.com/forums/showt...=154235&pp=100

http://www.rcgroups.com/forums/showt...=915522&pp=100

The Rafale can still be bought for ex. here : http://shop.wemotec.com/index.php?k=18&lang=eng

.
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Old Mar 10, 2014, 07:50 PM
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Rich Uravitch's Avatar
Florida
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S-3B Viking, twin 90mm HET, 6S per side. 82" span,17 #.
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Old Mar 11, 2014, 05:48 AM
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Fenton,MO USA
Joined Aug 2005
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Love the viking, great job.
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Old Mar 11, 2014, 10:53 AM
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Arngeir Blakseth's Avatar
Molde, Norway
Joined Jan 2001
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Quote:
Originally Posted by Martin Turner View Post

So I am looking for a Jet Kit - I want to build something!

Anyone know of proven plans and ideally a short wood kit for a large 120mm Fan EDF Jet ?. Not confident enough to scratch build a big jet.
YES!

Ziroli F9F Panther, lots of people have successfully built and flown this design. It's designed for a Dynamax fan so 120-127 fans will fit easily, the plane will fly fine on a 12S 5000W setup. Plans, short kits, retracts and canopy and whatever else you need is readily available.
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