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The Parrot AR Drone 2.0 is a consumer drone with a built in camera and WiFi network, that is easy to mod and has a large backing community. It is controlled via an iPhone or Android device, but can be modded to use a variety of things (such as an Xbox Controller) to fly it. It sells for about 300 USD.
Specs
Pros
Pro Has a large community
The Parrot AR Drone 2.0 is very popular with modders and hackers and has large communities with events such as NodeCopter.js, a full days event where developers team up in groups of 3 to hack.
Pro Many tools for hacking and modding already exist
The team at NodeCopter team have assembled a list of modules that can be installed on the AR Drone 2.0 such as face recognition or controlling it via your web browser. There is also SkyJack, a program for using your AR Drone 2.0 to hunt down and take control of other Parrot Drones. It uses a Raspberry Pi with an Alfa AWUS036H wireless adapter in order to interact with the WiFi networks of other drones around yours.
Pro The option Flight Recorder GPS adds useful functionality
As an optional purchase of about 127 USD, the Flight Recorder GPS can be added to the AR Drone via the USB port which adds a multitude of capabilities such as geolocation, selecting destination via a map, recording with a 4GB flash memory, returning to take-off point as well as stability improvements.
Pro Great value for money (~$300 USD)
For the amount of features you get with the AR Drone 2.0, the price is excellent compared to the other drones. For about 300 USD(or 420 USD with the GPS addon) you receive all the basic and some advanced features of most drones for about half the price.
Cons
Con Underpowered out of the box
For the cheaper price, the Parrot AR Drone 2.0 is less powerful out of the box. It lacks power, has a limited range and doesn't have a built in GPS. Out of the box the drone can only carry about 8 grams, which is extremely small compared to the other drones.The range can be increased with a simple range extender and the GPS extender can be bought from the website, but in order to improve the power, a motor and frame mod will have to be done, which is detailed in this video.