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Old Mar 14, 2011, 02:24 AM
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Do you mean on the skirt? I think it will add unnecessary complexity to be honest and i would think you'd be revving up fairly slowly anyway, but you may find when you get there that you will have to experiment with a few different fans to get the right balance between power draw and an adequate cushion, and your skirt design will be critical for this. The sweet spot for bag skirts (certainly at model scale and i have no reason to believe different at large scale) is to aim for a skirt/plenum pressure ratio of about 1.5.
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Old Mar 14, 2011, 02:26 AM
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love to see pics of this done
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Old Mar 14, 2011, 05:35 AM
Yes, I know it's upside down.
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Someone is going to see your work here and offer you a job.
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Old Mar 14, 2011, 03:45 PM
um.. yeah, I can make that fly
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United Kingdom, Milton Keynes
Joined Jun 2007
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Great looking project, Id build one just so I had an excuse to buy that awesome motor. beware though, Ive done some research on that beast and someone mentioned the bearings were dodgy on their one. another quick thought was if this all does go belly up (god forbid) with you in it, say an ESC stopps responding at WOT. Perhaps a master electrical cutoff switch (or something) in the cockpit might be an idea. pop onto youtube and look up a drag car called "white zombie". it's an electric brushless (I think, might be brushed) racing car, and their safety dissconnection device is very simple but safe. also watching them make a dodge viper look like a toyota tundra on the line is funny as hell!

Good luck! CJ
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Old Mar 15, 2011, 08:58 AM
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Quote:
Originally Posted by jpcwebb View Post
Do you mean on the skirt? I think it will add unnecessary complexity to be honest and i would think you'd be revving up fairly slowly anyway, but you may find when you get there that you will have to experiment with a few different fans to get the right balance between power draw and an adequate cushion, and your skirt design will be critical for this. The sweet spot for bag skirts (certainly at model scale and i have no reason to believe different at large scale) is to aim for a skirt/plenum pressure ratio of about 1.5.
I completely agree with you. I am not exactly sure what you mean by 1.5. I know that it would require .065789psi to sustain a hover. That is without the variable of the skirt.
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Originally Posted by wheelman20012002 View Post
love to see pics of this done
Soon....
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Originally Posted by Harrow View Post
Someone is going to see your work here and offer you a job.
It already happened about a year ago.
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Originally Posted by Carlos230023 View Post
Great looking project, Id build one just so I had an excuse to buy that awesome motor. beware though, Ive done some research on that beast and someone mentioned the bearings were dodgy on their one. another quick thought was if this all does go belly up (god forbid) with you in it, say an ESC stopps responding at WOT. Perhaps a master electrical cutoff switch (or something) in the cockpit might be an idea. pop onto youtube and look up a drag car called "white zombie". it's an electric brushless (I think, might be brushed) racing car, and their safety dissconnection device is very simple but safe. also watching them make a dodge viper look like a toyota tundra on the line is funny as hell!

Good luck! CJ
There is no doubt that I will have a kill switch. The escs have a switches to cut the signal so the motors would shut down. I think I have to program th escs though, bt not an issue.

Those batteries aren't your average sized lipos. An onboard fire would result in a serious burn if I do not notice anything wrong.
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Old Mar 15, 2011, 10:39 AM
MHA webmaster
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Sorry, i should have been clearer. For bag skirts, there is usually a pressure differential between the skirt and the plenum, and for good performance with minimum skirt bounce the ideal is to aim for a ratio of skirt pressure to cushion pressure of 1.5:1. This gives good stability and directional handling without suffering too much from surface deformation problems (particularly on water), though if you want to run on rough surfaces, a lower ratio nearer 1.2:1 would probably be better (and result in lower power drain due to feeding the cushion). However, it is easier said than done and depends on the skirt design, but can be influenced by fan, ducting, weight distribution etc. A good explanation is here: www.4wings.com.phtemp.com/tip/bag.html
You'll also need a manometer and connection to the skirt interior to measure this - or work to the theory and hope
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Old Mar 15, 2011, 10:43 AM
MHA webmaster
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sorry, accidental double post - damn smartphone
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Old Mar 15, 2011, 10:50 AM
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BTW, do you intend to run this on water or stick to dry land? If the former, you'll need to think about waterproofing your electrics, especially the batteries and escs.
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Old Mar 15, 2011, 08:27 PM
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HELP NEEDED ASAP!!!
http://www.rcgroups.com/forums/showthread.php?t=1407175
http://www.rcgroups.com/forums/showthread.php?t=1407184
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Old Mar 15, 2011, 09:08 PM
In the 20' glider range
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Why is your deadline so soon?
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Old Mar 15, 2011, 09:40 PM
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Because the stupid public school system chooses to keep private schools uninformed on everything. The fair is on the 15th of April.

Oh, this is meant to ride on all surfaces just like any other craft, but I have to start simple.
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Old Mar 15, 2011, 09:42 PM
In the 20' glider range
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Thats life for ya.
Best of luck having it done!
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Old Mar 15, 2011, 09:46 PM
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That means that I have to place an EMS order tomorrow. That costs as much as the order total itself. But it is best to spend the extra to have it in decent time.
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Old Mar 15, 2011, 09:52 PM
In the 20' glider range
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Ouch. Im sorry. Thats a bummer. You ordering it from HK? I have ordered EMS and not gotten it any quicker than basic.
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Old Mar 16, 2011, 10:25 AM
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Yep...
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