[Paparazzi-devel] Re: Steve Turners Post.

[Hugo Vincent]

Hi Steve,

I am working on a UAV project too; I haven't made a website yet, but 
have written and collected a fair bit of material in the attached PDF  
file (

SysOverview.pdf
Description: Adobe PDF document

) -- but I am not sure how the mailing list system will handle it. 
(It's still in a state of change, so ignore anything that looks 
unfinished or wrong!) Please feel free to use the ideas in it, and 
consider releasing your work under a GPL type license so we can all 
share :)

I have just looked at your website -- cool! I would like to know more 
about the airframe: did you design it? The specifications you came up 
with -- how where they generated/based on?

I have been playing around with SolidWorks/COSMOSworks (3D Cad and 
analysis plugin that does stresses etc, and aerodynamics), and XFoil 
(GPL airfoil design tool and simulator) trying to design an airframe, 
and am getting fairly bogged down in it all! I must say, just from 
looking at your website, that you sort of just got out the tools and 
started making it, with out really doing the design and calculations 
(no offense, I wish I could do that).

Also, for the airframe, especially the wings and tail-plane surfaces, 
you might want to investigate a technique called vacuum bagging, where 
you lay-up the foam with all the various composites, add an anti-stick 
film, put it in a sealed bag, and apply around 4-8 psi of vacuum 
pressure. Alternatively you can use the parts of the foam that you cut 
the wings from ("negatives" or something, sometimes called shucks), put 
your layed-up wing in them (with appropriate anti-stick protection) and 
puts weights on the shucks to apply pressure to the lay-up, increasing 
strength of the bond to the foam, and as a result, the strength of the 
whole wing, and allowing less epoxy to be used (less weight).

> Date: Wed, 21 Apr 2004 21:01:29 -0600
> From: "Steve Turner" <address@hidden>
> Subject: [Paparazzi-devel] Part Sources
> To: <address@hidden>
> Message-ID: <address@hidden>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>
>     I have been interested in UAV's for a while, and am attempting to 
> build one. I may try to build a paparazzi, and at least use some of 
> your ideas. You guys have done a great job. I am fairly new to the 
> AVR's and C programming, so it is a steep learning curve for me. I 
> have not yet located a source for the modem chip however. I have been 
> unable to find any info on the CMX469D3, but did find some info on a 
> CMX469AD3 (http://www.cmlmicro.com/Products/WData/CMX469A.htm). Is 
> this the chip you used? Looks like most everything else DigiKey has.
>     I am also wondering if your printer had any problems printing the 
> board to a transparency without smudging between the small pads of the 
> AVR's? I have a cheap HP printer, and some of my pads print out with 3 
> pads connected together. Maybe a higher quality printer would work 
> better.
I have had very good luck with laser printers and press and peel. With 
a little practice (especially with the chemicals i.e. correct 
agitation, heat etc) you can make very professional PCBs. Double sided 
is somewhat harder than single sided, as you have the added problem of 
alignment, but can still be done very professionally. But the best 
thing about purchased PCB's that I haven't worked out how to do yet, is 
plating of the board, especially through-plating of holes... Solder 
masks on purchased boards also make a HUGE difference when it comes to 
soldering the board. Hint: use heaps of SMD solder flux (the stuff that 
comes in a tube, it makes a huge difference).

>     I have a website with a little stuff on UAV's 
> (http://www.steveonweb.com). More just a collection of some of my 
> ideas. I have since moved away from the PIC's and on the AVR's. 
> Probably nothing new for you guys on there however. Thanks for any 
> ideas or pointers.
> Steve Turner
> Fort Collins, CO
> SteveOnWeb.Com


Hugo Vincent
address@hidden