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Electric Ducted Fan Jets Discuss electric ducted fan jets here including setup tips, power systems, flying techniques, etc.

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Old 10-04-2011, 04:59 PM   #1
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Default Home made thrust vectoring nozzles for EDF?

I've been thinking about tinkering around with a scratch-built EDF jet sometime in the future. I've seen prop thrust vectoring set up where the entire motor swivels. But, has anyone out there built a successful thrust vectoring nozzle for an edf jet? I've seen one offered online for $90, but that is way more than I am willing to pay. Plus its machined aluminum which is way overkill!

It shouldn't be hard to do, but was just wondering if anyone has something that is easy to build and works.

Thanks!

All of my landings are three point landings if you count the spinner, too
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Old 10-05-2011, 06:07 AM   #2
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Hi, This might give you some ideas, look at the video, it shows the vectoring nossel towards the end of the video, take care, Chellie

http://www.bananahobby.com/2120.html

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Old 10-05-2011, 02:10 PM   #3
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I don't know if you were thinking of one method or more, but I just realized there are 2 methods I've seen. One where the whole exhaust nozzle is gimballed, which seems difficult to make. The other would be to have directional vanes in the exhaust flow, which seems easier. I've seen a Banana-Hobbies F-15 someone had (For a little while...) with the nozzle vectoring, and the Phase3 Squall, I believe, had/has an optional kit with the vanes.
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Old 10-05-2011, 11:14 PM   #4
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You can purchase 2 axis ball gymbol thrust nozzles at Hobby Lobby. They have to match the edf size. Most are 64 or 70mm. The price is $12.99 for the SU-34. Try HLI34360711 for what they look like.
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Old 10-06-2011, 01:01 AM   #5
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Thank you for the help, everyone! I was thinking of a gimbal. I have seen vanes, but I think there is an inherent drawback to those. If you utilize a single vane, you are only deflecting half of the airflow. If you increase the number of vanes, you could be seriously restricting the airflow.

I have an idea in my rock-filled head for an easy gimbal joint based on the info share here. I'll see how it goes when I get around to it!

All of my landings are three point landings if you count the spinner, too
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Old 10-06-2011, 03:52 AM   #6
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I think the key thing to remember, is intake and exhaust areas are very critical to EDFs. The F-15 I mentioned earlier wound up crashing when the owner removed the vecoring nozzles and wound up losing a lot of thrust. I think a bigger nozzle creates more low velocity thrust, good for low end power, to a point. And a smaller nozzle creates high speed thrust. So there's a sweet spot somewhere. I guess it's kind of like the gears in a transmission. I believe shrinking the exhaust nozzle speeds the exhaust to a point, then creates too much back pressure or something, then loses efficiency. That F-15's exhausts were bigger without the vectoring gizmos.

Just food for thought!
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Old 10-06-2011, 11:03 AM   #7
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That's my understanding, too, xmech2k. The intake diameter probably isn't as critical, as long as it is at least the diameter of the fan housing. A bit larger may be desireable. The length of the intake is probably pretty important so that the airflow going into the fan is uniformly distributed over the fan area.

The exhaust outlet probably can be slightly smaller than the fan diameter. This will accelarate the flow, but puts more load on the motor. I have noticed that the nozzles of fighter jets adjust slightly as throttle is applied.

All of my landings are three point landings if you count the spinner, too
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