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Old Apr 18, 2014, 04:04 PM
Balsa Flies Better!
Stamford, CT
Joined Oct 2000
6,781 Posts

The advantage of twins is that that ducting gets pretty easy (splitters are harder.) I suspect that you'll have enough room in between the ducts for batteries- having done a small Arrow single (and I keep toying with the airplane as a twin...)

Size the airplane to the fans- not the other way around! The challenge with twins is that often the fans that you think should work in the airplane- well, they're too big for the ductwork. I'd recommend staying with 70 mm fans- there are plenty of them, lots of power systems, and a bit less expensive than the 90s.

If you haven't done an EDF before, I recommend getting your feet wet with something less complex than a twin. Balancing and assembling the fan can be something of a knack.

And yes, there's some theory on fan placement- check the Wemotec site. Pretty sure that ideal exhaust length is between 2.5-3x fan diameter but I could be wrong.

Don't get hung up on static thrust- a lot of the inlets we use don't work real well at delivering max static thrust but do fine once the airplane is in the air. Check Ken Williams thread on his F-100.


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Old Apr 19, 2014, 02:03 PM
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Kambalunga's Avatar
Deutschland, Hessen, LA
Joined Jan 2009
1,244 Posts
An Excel sheet for delta COG calculation.
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Old Apr 22, 2014, 10:06 AM
killickb's Avatar
The Villages. Florida
Joined Jan 2005
1,591 Posts
Here is my 106, you can see the line marking my cg just in front of the wheelwell. I have good pitch control at this position.

Not sure where it is with respect to the MAC but the wing is 22 inches long from where the leading edge meets the inlet and the cg is 7.5 inches from that leading edge point. Maybe you can interpolate that to fit your model.
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Old Apr 24, 2014, 02:10 PM
It wasn't me...
DanSavage's Avatar
Trabuco Canyon, CA
Joined Nov 2000
4,591 Posts
Originally Posted by killickb View Post
Here is my 106, you can see the line marking my cg just in front of the wheelwell. I have good pitch control at this position.
Have you flown your -106, yet?
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