Replies to This Discussion

Permalink Reply by Ken on January 15, 2011 at 4:31pm

The sky is bright. Really, really bright. LEDs don't have a chance.

Keep your fuse narrow. Make your wing & tail surface with thin carbon fiber spars, balsa ribs, and cover in clear polyester film (monokote, coverite, etc.)

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Permalink Reply by Johann Van Niekerk on January 15, 2011 at 4:40pm

Thanx Ken

Unfortunatly I can not redesign my airframe just for this purpose but would rather like to learn how to work get this up and running this will be the first step of many to come ! 

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Permalink Reply by Chris McNair on January 15, 2011 at 4:39pm

Just some rough calcs and a guess on weight tell me you would need 300 of these sensors to cover a 12'x36" wing. At .50g each (guessing) that's 150g for one side. Could be heavy!

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Permalink Reply by Johann Van Niekerk on January 15, 2011 at 4:42pm

Hi Chris

yes that would be the idea problem but for now jst one is enough and replicate the same color over the whole wingspan underside then later refine it.

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Permalink Reply by Ritchie on January 15, 2011 at 4:44pm

You have jumped in but there are plenty of tutorials.

 

You have a colour sensor (those sensors are reputed to be brilliant), an arduino and an RGB LED. The colour sensor sees the colour you have pointed it at and the RGB LED produces the colour. Now what I believe you mean to accomplish is that with the colour sensor pointing up to see the sky, this colour will then be produced onto the wing underside to reduce the difference in colour between the wings and the sky.

Its a nice idea but you will need more than an RGB LED to accomplish it. The LED will produce a spot of coloured light only. What you require is a perfectly diffuse colour spread across the entire wing underside with the correct luminance. I cannot think of any way a normal person could accomplish this and have it flyable.

The non-normal ways that come to mind are:

OLED wing underside - luminance and colour and perfectly linear across the area thanks to the being individual LEDs effectively. Who could afford to try and build something like this :D

6mm plastic diffuse layer (using 5mm standard LEDs) - RGB LEDs at one end with diffuse area showing the colour deteriorating towards the end. Do plastic wings fly?

Metamaterial skin - metamaterial tuned to visible spectrum would absorb "all" light and render the craft basically black and the night sky not just stealth bomber black. 

 

If you are worried about being spotted then add rubber sheeting. Its not exactly RAM but will help in the dead of night. Submarines do it to absorb sonar signals. It might make the plane heavy though. You could of course paint it black and sand it.

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Permalink Reply by Johann Van Niekerk on January 15, 2011 at 4:52pm

Hi Ricthie

I know where you get the black from but I want to do this for a other project mainly for day missions.

What you said bout diffuseing the light has comee to mind but my think of that was on a UAV with wing span of 60" at 399 feet ;-) just more or less getting the color right over the shadows of the wing underside should help a lot.

 

The Leds would be mouted on the fuselage pointing up towards diffrent gradients of the wing and should diffuse naturaly over the wing.

 

I would like to refine it at later stage but for now just want to get it working.

Your thoughts?

Thanx for the reply

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Permalink Reply by Johann Van Niekerk on January 15, 2011 at 5:27pm

There is always these

String of RGB LEDs

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Permalink Reply by Ritchie on January 15, 2011 at 6:58pm

Yep I went on after I commented and thought of you.

Mass will be the problem to be honest. If using say 3 RGB LED projectors to cover the 4-5" projected spot of appropriate colour this would help hide the plane but I'm fairly sure that RGB LEDs have not been developed that are powerful enough to work in daylight effectively (dusk it might)

I have a 5W luxeon (HUGE heatsink) white LED and with focusing optics its still useless. At night though its like a search light.

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Permalink Reply by Johann Van Niekerk on January 16, 2011 at 2:09am

Ya that project was bit of a disaster .

First i built it for him and trained him how to do it then when i wantted to post the biuld log he refused because of the natuur of the job.... week later got a phonecall saying that he completely crashed it to pieces ..... geuss how?! " he thought he switched it to Auto" he didnt and just left it to have a 600 foot free fall.

 the sadest part for me was he had two of these on it .

 

A well ..........LOL

back to project ! I know the LEDs you talking bout they brillant wich makes me think if they going to be shining in the shadow of the wing they nust have enough light to make a diffrence, I mean if you paint the underside of the wing a blue/white/grey color im sure it will work.

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DistributorPermalink Reply by Martint BuildYourOwnDrone.co.uk on January 16, 2011 at 5:17am

Hi Johann,

Interesting concept, I would recommend looking at oled and fibre optics for this project, money willing.

Regards

Martin

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Permalink Reply by Johann Van Niekerk on January 16, 2011 at 8:05am

Thanx martin

I was thinking of Fiber optics and the process would be fairly simple ...if I had nano  robots to place them correctly ;-)

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Permalink Reply by Sarel P. Wagner on January 16, 2011 at 10:49am

Johann,

 

Thinking outside the box, build a traditional type wing but use very thin carbon fibre for the interior structure  and use clear plastic cover material, Now only worry about the fuse :)

 

Rgrds

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