One of the first phase of my development and construction is the design and CAD model of the body, I have decided to construct the body from scratch.
I have developed two design ideas which are inline with my Product Design Specification. The first is a H frame layout, the other an X frame.
In a H frame resembles a H like this quad copter below:
This is the well known 3DR Iris quadcopter which is an extremely well engineered drone.
An X frame is the most common, it is seen below:
The benefits of a H frame is that it is possible in my opinion to build a more aesthetic frame and a more unique frame, H frames can also be better streamlined in forwards flight than an X frame, so it is possible to achiever higher flight speeds. However the benefits of an X frame are that they can fly in any direction the same, where as a streamlined H frame might struggle flying sideways even if not the flight characteristics are different if flying in different directions.
Here is my first design concept 1, note the designs will require development and not look exactly the same as these. The construction of both of these will be composite, specifically Carbon fiber. The construction of these would be done in a simmilar way. I shall create an exact CAD 3D model, which I shall then 3D print in ABS plastic. However this plastic is quite weak, and would not be able to cope with the forces involved. My solution is to print a thin shell, which I shall cover in a carbon fiber using a laminate process, then sanded up to a high Finnish. Once I have this shell I shall inset carbon fiber bulk heads (which I shall cut from a 2mm carbon fiber sheet). The shell will also incorporate fixtures for the bulkheads. There will be slots in these bulk heads to allow the insertion of a carbon fiber “deck” which I can mount the components to, and other various fixtures.
This design is the H frame design, it incorporates a very streamlined solid body with streamlined arms and motor mounts attached to it. There will be a single hatch at the top, and a clear dome at the front which is where the camera system will be mounted. Landing gear would be the motor arms themselves as there will be no under slung payload, everything will be internal. The hatch will allow access to the internals, and replacement of the batteries, the hatch will be incorporated into the structure so might need to be screwed in with removable screws, or I could develop some sort of quick release. This chassis will be easily waterproofed as there is no exposed electronics apart from the motors, however the motors, do not need waterproofing. The motors will actually be slightly tilted forwards in order to allow “cruise” level flight, high airspeed is the main benefit of this chassis.
This is the X frame, it will feature a solid hub shell, made in the process stated above. The arms will attach to this hub in an X configuration and will be removable, standard carbon fiber tube arms. There will be hatches top and bottom. On the bottom there will be a rear hatch to allow replacement of the batteries. There will also be a front hatch, which will be left open, inside there will be industry standard mounting rails to allow the under-slung attachment of accessories such as in my case the tarot gimbals and GoPro camera. The Landing gear will be angled backwards as to not be seen in the view of the camera. The top hatches will allow access to the electronics. It will be harder to waterproof this system.
Pros and Cons:
- Very streamlined – should be able to achieve a higher airspeed in the forwards direction.
- Very very good looking, it is a really stunning looking chassis especially in full carbon fiber – in my opinion of course.
- Extremely unique looks!
- Easy to waterproof.
- Unique selling point – the chassis is extremely unique!
- Sideways flight performance will be bad.
- Arms are not easily replaceable if they break they will have to be custom made.
- Very large single piece to be printed on the 3D printer.
- Will not able able to mount any other payloads in the drone other than a propriety gimbal and a gopro.
- Under slung payloads will ruin most of the advantages of this frame.
- Small viewing angle out in the dome, and the dome might cause distortion in the camera footage, unless I created a moving dome camera system, which is even more propriety.
- Sideways, forwards, and rearward performance will be very similar.
- Pretty aesthetically pleasing in my opinion.
- Will be able to easily change the payload, lots of room underneath for different payloads, wide viewing angle underneath.
- Easy to replace the arms, since they are just standard carbon fiber tubes.
- Will be a small single piece to 3D print.
- Harder to waterproof.
- Higher drag due to under-slung payload, so not as fast as the other design.
- Not quite as good looking as the other.
I have decided that the X chassis design will be the one I am carrying forwards at this time. However both design are good designs and I could equally carry the H frame design forwards perhaps in a different project. The both have their benefits. The reason I have decided to take the X chassis forwards is because of manufacturing constraints. I have a limited print size on the 3D printer I have access to, which this design exceeds. In order to make the design work with the printer I have access to I’d have to make sacrifices which I don’t want to make. Also I will have to design a custom gimbal and maybe even a dome system which will be very difficult.