This post might be a little premature in that I'm just getting started, but after hanging out at DIY Drones for a few years and doing little more than adding editorial comment to other's posts, I'm anxious to share my real DIY Drone project. Since all of the hard work has already been done by others in this community with regard to the autopilot, this blog will focus on the airframe.
I decided to turn my DIY Drone project into my first attempt at designing an airframe from scratch. I have built from plans before, but never went this far. I chose the IAI/AAI RQ-2A Pioneer to model. First, I like the simplicity of the design and felt it would be fairly easy to model. Second, I prefer a more traditional tail to the v-tails that seem so popular with UAVs. I'm sure there are very good aerodynamic reasons for that, but they just don't appeal to me aesthetically.
My plane will be a 1/3 scale model of the Pioneer. That gives it a wingspan of 67-1/2". The design of the main wing and empennage assembly is pretty much done. Next I'll move on the fuselage. My plan is to have all ribs and formers laser cut.
I'm using Google Sketchup for the design work. It has been very easy to learn. The most difficult thing so far has been figuring out how to get 2D plan-view prints out of Sketchup. It's not really geared toward basic engineering. It's primarily a 3D modeling platform. However, with a little playing you can get the printouts you need.
When finished, the plane will be equipped with APM, telemetry and on-board video (of course). I will most likely learn APM on a smaller ARF, though, before risking this airframe.
I'll post a few more images in this blog, them move over to just posting progress photos in an album on my DIY Drone page. The first one below is the real thing hanging in the Air and Space Museum in Washington DC (not my photo).
Thanks.
Paul
This is my current design for the boom saddles that will attach to the horizontal stabilizer. I'll try to shape them from a layer of four 1/4" balsa ribs. The channel is for servo leads.
The boom attachments for the main wing will be a little different and will be integrated into the wing itself. All three spars will pass through the supports. The wing sheeting itself will also add strength to these supports.
Ribs will be 1/8" balsa. Spars will be plywood with 3/32" balsa webbing. Main wing sheeting will be 3/32" balsa. Tail feather sheeting will 1/64" ply.
Vertical stabilizer and rudder.
Finally, a little fun I had with Google Sketchup before starting the plane design. I modeled the CCD camera I'll be using and figured out how to model the clear dome.
Comments
In order to import airfoil coordinates, you'll need the points cloud plugin for Sketchup. It's available HERE.
I use a clark-y. The type I used to inspire my design is the Ruag ADS Ranger, a copy of the IAI Scout (http://en.wikipedia.org/wiki/RUAG_Ranger). But the wings have a different design. One of the parts I still use of this design is the that the wing are low decker type. Virtually all drones have the wings placed on top of the main body. I will use its lading skid system too. It's not so clear from my photos but I actually have installed these skids, but have wheels on it. It's a robust design: I used a heavy hammer to test it ;-)
I want the drone to be capable to land of difficult terrain.
... I didn't know Sketchup was able to import airfoils. Good to know.
Thanks for the comments!
@Justin -- Yes, this is the free version of Sketchup. The Pro version (~$500) would solve my printing problems, I believe, with its "layout" function. However, forum posts suggest downloading the 30-day free trial version for a one-off project. When I'm ready to print, I'll probably do that. I'll have to look up the video system info again. I'll post that later. I am open to suggestions there, though.
@Marco -- I did see your photos before and noticed the resemblance. The Pioneer was designed by Israel Aerospace Industries (IAI). I think AAI here in the States might have licensed the design. This one dates back to the 80's. The main wing airfoil is NACA 4415 and the tail section is NACA 0012. I probably sound like a commercial for Sketchup, but it turns out to be very easy to import airfoil data (point clouds) and get an exact shape. I was also wondering about the control surface size, and in particular the ailerons. However, I am getting some good advice on this design and they didn't seem concerned.
Thanks again for all the comments.
Paul
Nice. It remembers me he Sketchup work I've doe for my drone project. I decided to copy the drone used by the swiss army (an outdated copy from a israeli drone in the early 90's). The actual photos of it are here: http://www.diydrones.com/photo/img0457-2
Finally during the first build phase I changed the design and used an inverted v-tail. I think there is no way to build the real thing. Plans are good but the most of time but it turns out different.
What profile do you use? Looks like a clark-y. Maybe you may consider to user bigger control surfaces.
Nice job !
I assume this is the free version of Sketchup ?
Also, what camera do you plan on using ?
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