Posted by Scott James on February 23, 2008 at 9:00pm
Well it has taken me about a month but I think I finally have a plan for a UAV.Please excuse my childlike MS Paint style diagrams! This is what I would like it to be able to do. It is using in the BASIC Stamp and this GPS receiver.1. Have waypoints that include altitude.2. Be able to take Digital Photos3. Have a lost plane alarm after landing (or crashing!) in long grass etc… This could be turned on via Aux channel on the receiver. Alternatively this could turn on landing lights for night or dusk landings.4. Control of the autopilot from the Gear channel that totally bypasses the Basic stamp in manual control mode in case of Basic Stamp Problems.5. 2X16 LCD (optional) to display maximum altitude reached or maximum speed reached, waypoint info etc.. (I haven’t really thought about this bit yet).6. After all that was working…. (and if the thing can still get off the ground from all the extra weight!!) another thing that I was thinking about was having a voltage sensor (Lipo alarm) on the main battery. (I have one of these on my Trex 450 SE V2 Helicopter) It would monitor the main battery voltage, when the voltage dropped (if it was a 11.1 V Lipo) to say 10.5V the battery would be almost 80% depleted. (after 80% the battery will be damaged)The voltage sensor would then trigger a relay that would switch to a smaller backup battery and also trigger the BASIC Stamp to return to home. The home co-ordinates would be obtained when the autopilot was engaged.Here is a circuit I found for a RC Switch, I have not tried this yet. This is the relay I think I will use. (I had to because of the name!) [UPDATE 2/3/8] I am going to use this instead to save space and weight.The other idea I had was for altitude control. If the Basic Stamp is controlling the elevator for altitude I can see that it might be easy for the UAV to get into trouble as it does not know the angle it is climbing or descending. It could be resolved by adding more sensors but I thought this might be easier and less programming.I am going to mount the FMA Co-pilot onto a see saw mount that is controlled by a servo. The Basic Stamp would then just control that servo. If you wanted the UAV to climb at an angle of 10 degrees, just move the FMA servo by 10 degrees.The FMA Co pilot would then control the elevator to keep the FMA co pilot level, which means the UAV would be climbing by 10 degrees. (I think)Also in the altitude subroutines I was planning to turn off or turn down the throttle channel when the UAV is descending to save power. And then switch it back to where it was when it reached the desired altitude. Maybe even add a bit more power for climbing. After a few tests I should be able to work out what percentage the throttle channel would need to be at to hold altitude.This is the Plane I am planning to use for this project, There seems to be more room inside for electronics that a foamy.If anyone has any better ideas or reason why they think this wont work too well please let me know. As I start building I will post some pictures.Thanks!
I’m pretty sure I can fit one 11.1V 2200mAh 3S LiPo behind the wing in the fuselage and another one under the wing (if needed) leaving the front section for electronics. That’s why I chose the Omei 2000 over a foamy. (Multiplex easy glider) I will make up my own circuit board for the Basic stamp and other electronics to save space. I also think that this model may be a bit more aerodynamic and be able to travel a bit faster / further than a standard plane. Also I think it would look cool as a UAV.
All that being said I will probably be posting is a few weeks that Chris was right and it doesn’t fit but I’m going to give it a red hot go! On the plus is if it doesn’t all fit I have a mate that will buy it as he want’s one just for normal flying.
Are you sure there's enough room in there for the electronics?! The problem with using sailplane airframes is that the equipment bay is not at the center of gravity. So even if you are somehow able to cram all the electronics in the nose (plus batteries), you may have to add weight to the tail to keep the CG where it should be.
Why not use a high-wing trainer, which have big equipment areas under the CG, for this project?
It looks pretty good but seems a bit hard to find.
The main reason I am buying my Omei 2000 from a RC shop around the corner for the fact that they are close and parts are easy to get! Thanks for the suggestion Ian.
Hi Scott
have you looked at the smd accipiter badius as an airframe.
this design will recover to straight and level if all controls centred.
and very quickly at that.
I plan to enlarge this design 2.5 times because of the distance i need and also the wind factor been heavier means less blown off course.
Comments
All that being said I will probably be posting is a few weeks that Chris was right and it doesn’t fit but I’m going to give it a red hot go! On the plus is if it doesn’t all fit I have a mate that will buy it as he want’s one just for normal flying.
Why not use a high-wing trainer, which have big equipment areas under the CG, for this project?
The main reason I am buying my Omei 2000 from a RC shop around the corner for the fact that they are close and parts are easy to get! Thanks for the suggestion Ian.
have you looked at the smd accipiter badius as an airframe.
this design will recover to straight and level if all controls centred.
and very quickly at that.
I plan to enlarge this design 2.5 times because of the distance i need and also the wind factor been heavier means less blown off course.