|Jan 31, 2008, 10:18 PM|
G. Heights, Illinois
Joined Feb 2006
Took notes on chapters two and three. These first three chapters were on the basics of motion, lift, drag and the boundary layer. I now know much on how to calculate and think about the basics of a planes motion and the forces acting on it in flight. The next chapter is called 'Basic Model Performance Problems' and I assume it will teach me how to fit these ideas together into designing an actual plane.This seems likely because the chapters after that are about more specific topics, such as reducing vortex-induced drag, choosing an airfoil and things like that. And it is as long as the previous three combined. In the end this book will only teach me about the theory of how model planes work, and not actually about how to build one. For that I found a apparently great series of books by Harry Higley that is all about the practical side of designing and building model aircraft. So I have purchased his 'Master Modeler', 'Harry's Notebook' and 'All About Engines' books. I'll post something here after reading through one.
My organization of this project has changed somewhat. Also, after going through some of the new resources I found recently, and some more thought, I have also more or less decided what'll be included.
Airframe-Frame and gear.
Learning about how to design this right now. Will be single engine and slow and stable; easy to fly. I hope to also make it able to take a large payload for any sort of future projects. I'd also like to include an external refueling point, a battery charge point and retractable gear. Another idea is to have most, if not all, of the electronics accessible without having to cut the plane open. Also considering EMI shielding and heat sinks or ventilation for hot electronics.
Propulsion-Engine and fuel systems.
I don't know exactly how big the engine will need to be yet. I'm hoping for a four stroke diesel, but a four stroke nitro will do. I'd like a pressurized fuel system even though I don't technically need it. I'd like it for the efficiency mostly, but I also want the freedom of placing the fuel tanks where I want them. Problem is, I don't know of any four strokes with a fuel pump. Still gotta figure this one out.
Electrical Power-Starter/generator, batteries, control circuitry
LiPol batteries and this starter will remotely start the plane. Then the starting mechanism (provided it isn't a one way ratcheting one) will act as a power-take-off and drive the starting motor as a generator. The tricky part is the control circuitry. LiPol batteries require some special circuitry to charge for one thing. For another I'll have to find a way to apply the batteries directly to the starter one way, and then go through a DC/DC converter and out to electronics and batteries the other. I think I could find a LiPol charger in board form, but I might have to make the rest of it myself, perhaps with the aid of a control system microprocessor.
Control-Servos, radios, microprocessors and input device.
A regular RC controller (likely the one I'll get with my RC simulator) and perhaps a board of switches interfaced to a Parallax Propeller microprocessor. Throttle, elevators, ailerons, and rudder will each have their own dedicated core reading the controller and translating to the transmitting radio. On the plane there will be similar dedicated cores decoding from the radio and controlling the servos. Non-essential controls like flaps, gear, etc. will be handled by another core. There may exist the need to have yet another core handle the coordination of output data. A pan and tilt system may also be used for the camera.
Video-Camera, radios, LCD screen
Video goggles proved to be too expensive for a decent set. An LCD screen with sun visor would be ideal. All that remains for me is to choose a range.
Telemetry-Data capture, output device
This may work one of two ways. A simple OSD type telemetry will give me altitude and a GPS 'to home' direction arrow. It is less complex and cheaper than the other alternative which is to piggyback an RCATS system on the control radio. This will however give me a broader range of data and the advantage of live laptop display, GPS position on Google Earth, data recording, etc. This option will also decrease my bandwidth for the control system, since I will have to operate as a full duplex instead of master-slave.
I'll use the BTA AS-07G autopilot. It's expensive, but all controlling sensors are fully independent and it is made from a military grade design. If there is one thing I want to make sure will operate properly, its the autopilot. As an added bonus it includes a feature that 'smooths' out the input. Climb but not stall, decend but not dive, etc.