whatmovesyou
I am presently making my dual EDF J-20 and need to make my 2 extension ducts (16 " long) for the 70 mm fans. The ID of the nozzle and TV is about 3" in dia. So how to bend the foam? Some scour it, some use hair dryers, but I found another way for some builders.

nozzle 018.jpg  nozzle 019.jpg nozzle 020.jpg 

I needed to do 2 ducts 16'x9.5" . Our house has a hot water (200 degrees) heating system with a 1.5" pipe in the cellar. The piping becomes the source of heat to mold the shape.

The first thing I did was make the two ducts and put a cut line at one end so the TV ridge fits in straight.
Next, holding the flat piece behind the pipe and then start moving slowly and bending( I keep my hands on the backside of the flat plate) from one end to the other. Go back and forth numerous times bending a little until you reach the desired dia.

If you look at the third picture, you can see a old rubber band brings it together with very little force. I use to glue and tape the ducting, now just tape it because it doesn't need much to keep it together. The second picture shows it by itself after the heat molds it. Both ducts took 20 min to do.

I made a transport similar to FoamandTape and bent the curvature of the two wings using this method. I just purchased depron and if you notice the white piece, I found it shapes very nicely as you can see in the second picture.
I like to design and fly unique planes.
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dtribby
How do you think it will perform/weigh in compared to Crankshaw's rolled transparency films?
Yes, I've known that I'm "different" for some time now...
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whatmovesyou
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How do you think it will perform/weigh in compared to Crankshaw's rolled transparency films?


The ducted material is used as part of the frame of the airplane for stiffness. I cut out the area of foam where I am going to place the EDF-thrustvectoring nozzle, and glue the nozzle assembly in. It is designed so the thrust line is inline with 1/2 height of the battery
I like to design and fly unique planes.
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unclejamal
i found the following video in this forum: 'http://pfmrc.eu/index.php?/topic/50480-mig-29-model-drukowany-na-depronie/page-5'http://pfmrc.eu/index.php?/topic/50480-mig-29-model-drukowany-na-depronie/page-5



i like that
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quorneng
The duct on my Fieseler 103 (V-1) is made of 3mm Depron and is 28" long.Complete2.JPG 
No bending required as it is made up from 22 full length Depron 'planks' build up around a mandrel. actually a cardboard tube.
DuctRear.JPG  Very light and remarkably strong. In fact the EDF is simply glued in at the front and retains the bell mouth.
DuctFront.JPG 
It appears that 'planking' is not a popular solution to create EDF ducts.
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Wildthing
Quote:
The duct on my Fieseler 103 (V-1) is made of 3mm Depron and is 28" long.Complete2.JPG 
No bending required as it is made up from 22 full length Depron 'planks' build up around a mandrel. actually a cardboard tube.
DuctRear.JPG  Very light and remarkably strong. In fact the EDF is simply glued in at the front and retains the bell mouth.
DuctFront.JPG 
It appears that 'planking' is not a popular solution to create EDF ducts.

With the grey Depron I was able to roll a 70mm diameter tube, no heat or score lines. I used the wife's rolling pin using a fair amount of force and then slowly started rolling it by hand around the rolling pin and then moved to a smaller diameter tube I had . This was using 6mm Grey Depron so 3mm should be really easy.

2017_0421_115428_003.JPG 
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