User:VAMK

Vaasan Ammattikorkeakoulu - Vaasa University of Applied Sciences

Introduction

This page is part of a final thesis project made for Vaasa University of Applied Sciences. The idea in this project was to implement the Paparazzi hard and software to an RC airplane. The project began in June 2009.

The project is sponsored by WRD Systems

Hardware

The Plane

After a long period of choosing the plane, the Sig Kadet was chosen to be the one. Below are listed some characteristics why it was chosen.

• Big wing area (easier to control)
• Powerful electric engine (ability to take up extra payload)
• Light
• Semi-ready built (no balsa work)

In the process of choosing the plane the following properties of the plane had to be decided such as following just to name a few:

• plane type
• engine type
• engine size

There are several matters that needed to be taken into consideration when choosing the plane type. Different types of planes have different weight, dimensions, fuselage size, manoeuvring capabilities, maximum pitch angle, stall speed, wing tip design and so and so on... Just like there are thousands of different kinds of real airplanes, there also are thousands of different kinds of model airplanes available.

These model airplanes come in many types and sizes ranging in weight from a few hundred grams to several kilograms and in dimensions from a half meter wing tip size to even one meter. Some of the model are so called "ready-sets" these come with comfort of not having to build it yourself but have the down of being difficult to customize the others are semi-ready or DIY -models. We were glad to notice that there was plenty of room inside the plane to fit extra payload (the Paparazzi electronics). What we were looking for was an easy to build and fly aeroplane with enough power and space to carry some payload, the payload being the Paparazzi autopilot hardware that weighs about 300g.

Making decisions in purchasing an aeroplane is a win-lose situation. On all situations where you win there is always a downside where you lose. For example: a bigger engine brings power and speed but adds weight and either the fuel tank or the battery takes space also you can't fit a big engine in a small plane, more wing area brings more up-thrust and stability but adds air resistance thus hindering speed and losing power to win the drag.

If we had been looking for an airplane for just for flying that would have been easy but the choice was difficult because we needed the ability to carry payload and none of the RC models are designed to carry extra payload. Even if you can fit with extra payload and your plane being able to carry it, the balance point will be different from what the manufacturer has designed and if you started correcting it with extra balance weights you lose power because the plane has become heavier. It is not so disastrous if the extra weight is located near the nose of the plane but if you are forced to place it near the back then the plane becomes unstable. Adding extra payload to an already heavy plane doesn't have such a huge effect on balance than it would have on a light plane. For example: if you add 300g to a 3kg plane the new weight 10% greater than the original but if you had put the same weight in a 700g plane the new weight is about one and a half times as big as the old weight.

Choosing the radio controller is much simpler because they all basically work the same way and the only difference is the number of channels it can use. When choosing a radio controller, especially with Paparazzi in mind, make sure to buy a controller which has at least one more channel than the manufacturer recommends.

You can find SIG manufacturer site here.

Engine Type Comparison

Pros for electric engines:

• simple starting and stopping - can be turned on and off in mid air by just adjusting the throttle
• no dangerous liquids needed
• less noice than in combustion engines
• less vibration than in combustion engines

Cons for electric engines:

• useally less powerful than combustion engines
• charging the batteries needs much controlling especially Li-Po which also need a special charger
• charging takes more time than refueling a combustion engine
• different kinds of batteries need a different charger

Pros for combustion engines:

• powerful
• refueling is a quick procedure compared to charging batteries

Cons for combustion engines:

• vibration
• unable to restart engine while airborne

Radio

• Hitec 6 Optic Sport

The receiver is also from Hitec, it's a HFS-05MS.

In order to use this one with Paparazzi, the PPM signal can be easily obtained as shown here:

The receiver works like a charm.

Battery

• Li-Po 1300 mAh 11V.

Why Li-Po? "Li-Po batteries are light and small and have large storing capacity. As rule of thumb Li-Po batteries have four times the capacity compared to same sized and weighed Ni-Mh batteries".

Software

Used Programs and operating systems

All of the programs were run on Mac OS 10.5 and virtualized Ubuntu 8.04 on VMWARE Fusion 2.0.

A VMWare image containing Paparazzi as well as Wine+U-Control is available here. It is based on Ubuntu 8.04 LTS, but has most of the standard included tools and sofware removed.

Linux

• Paparazzi GCS

Mac

• VMWARE Fusion
• Flight Gear

Simulation Example

In the screenshot you can see a Paparazzi GCS run on Ubuntu in a virtual machine and Flight Gear run on Macintosh. The navigation signal is broadcast in the local area network using UDP.

The reason why there's no land under the plane is that there were no landscape textures loaded into the Flight Gear at that moment.

How to Launch Simulation

Check the Paparazzi Wiki here.

Here's is a shorcut for Mac users to launch Flight Gear to see the simulation.

tell application "Terminal" to activate
try
	tell application "System Events"
		keystroke "cd /Applications/FlightGear.app/Contents/Resources"
		keystroke return
		keystroke "./fgfs.sh --fdm=null --native-gui=socket,in,30,,5501,ud"
		keystroke return
	end tell
on error
	display dialog "Error: could not launch FlightGear. Is it installed? Please download and install FlightGear to Applications folder." buttons {"OK"} default button 1
	set download_url to "http://www.flightgear.org/Downloads/binary.shtml"
	open location download_url
end try

The run this open Script Editor from /Applications/AppleScript copy paste above code and compile and run. To save it as an executable you must "Save As" and click the "Run Only" to true.