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Old Mar 20, 2013, 07:12 PM
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Joined Feb 2013
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Hmmm well I may have to look into the shirtless then but I built one out of cheap foam and it didn't seem to work well. But the foam was so cheap it wasn't perfectly straight. By skirt being thinner are you referring to widening the hole in the bottom of the skirt? Would you suggest lengthing the hole also?
-Mike
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Old Mar 21, 2013, 04:05 AM
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Staffs, UK
Joined Nov 2003
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The skirt is the bit round the edge...it needs to be narrower all round. That will make more area for the actual air cushion (which is what I think you're calling "the hole in bottom of the skirt").

I'm not sure you've quite got the idea of a hovercraft yet....it doesn't actually ride on the skirt. It rides on the cushion of air inside and flowing under the skirt. The purpose of the skirt is just to hold that air cushion in place (that's oversimplified but not far off). The point is that to carry a load what you want is more pressurised air NOT more skirt .

Steve
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Old Mar 21, 2013, 05:48 AM
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Australia, VIC, Bass
Joined Jan 2013
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if you want to try the foam edge idea maybe start with a new model as big as per
permitted - cut a strip of the flexible foam about 10 x10 mm and glue it to the underside of the model level with the outside edge
position the lift fan towards the front or back so the middle position is where the payload can go - also try reversing your motor / fan mounting so the prop is above the motor level witb the top of the duct
make the prop a neat fit in the duct with about 2-3 mmm clearance
you may need to run the motor at full power to develop enough pressure to lift the load otherwise the prop may stall and. it supply enough air , or alternatively use a 4 bladed prop
Given the problems you are having with the bag skirt I think this approach could be worth a try
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Old Mar 21, 2013, 11:53 AM
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Quote:
Originally Posted by slipstick View Post
The skirt is the bit round the edge...it needs to be narrower all round. That will make more area for the actual air cushion (which is what I think you're calling "the hole in bottom of the skirt").

I'm not sure you've quite got the idea of a hovercraft yet....it doesn't actually ride on the skirt. It rides on the cushion of air inside and flowing under the skirt. The purpose of the skirt is just to hold that air cushion in place (that's oversimplified but not far off). The point is that to carry a load what you want is more pressurised air NOT more skirt .

Steve
Haha I do get the concept now, at least the simplified version of it.

Quote:
Originally Posted by windnsea View Post
if you want to try the foam edge idea maybe start with a new model as big as per
permitted - cut a strip of the flexible foam about 10 x10 mm and glue it to the underside of the model level with the outside edge
position the lift fan towards the front or back so the middle position is where the payload can go - also try reversing your motor / fan mounting so the prop is above the motor level witb the top of the duct
make the prop a neat fit in the duct with about 2-3 mmm clearance
you may need to run the motor at full power to develop enough pressure to lift the load otherwise the prop may stall and. it supply enough air , or alternatively use a 4 bladed prop
Given the problems you are having with the bag skirt I think this approach could be worth a try
I'm not sure reversing the motor mount would make much difference imho. Though I may take my last bits of foam and try the skirtless since your are pretty sure that will work for us. The flower pot is within 2mm tolerance of the side of the prop. I think it will supply enough air, just need to get the skirt right.
Thanks again,
Mike
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Old Mar 24, 2013, 05:41 AM
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Australia, VIC, Bass
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im sure you'll get it working but whatever skirt is used you'll need to put the payload close to the CG
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