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Inspiration

Posted by Gunnisilli , in Frame Work 04 March 2012 · 174 views

As I am now in the process of designing my frame, I would like to go over some of my favorite designs and look at what inspiration we can draw from each one of them.

First I would like to say that I am a total newby in the field and I am currently building my first Quad. So many (if not all) my points could be total bologny. However, since I would like to do a good job of designing my quad and hope that many will find the design useful, I throw myself at your mercy :P

As I talked about in my previous post, the plan is to make a "easy to build" frame for areal photography with a fixed camera.

So, perhaps not so unexpectedly I am going to have a look at the VC-450.

VC-450

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Generally considered to be one of the best frames out there for FPV and just by looking at it, one can easily see what so many people like about it. Although the propellers are in view during photographing, I still want to take what knowledge I can get from it.
All parts are made out of the same flat material (G10) which make fixing such things as ESC and RXs to the hull and arms, really easy.
The arms consist out of vertically aligned plates which give support, where it is needed. My guess is that there is very little horizontal stress on the arms, so this is a great way to keep the frame light and lowering moment of inertia.
The center plate has a flat edge between the arms, which is handy for fixing cameras and equipment to the frame.

All in all a great frame, and I will take allot of inspiration from it :) However there are some things that I don't think are so nice... Here are a few.

My largest complaint concerns the design of the legs. They are very bulky around the mid section, but then get much thinner where they connect to the center plate. For a pure strength analysis... this is totally tits over arse. Just by looking at it, I can tell you exactly where it is going to break if you apply horizontal pressure to it.
Now there are a couple of reasons for them to design it like this.... One is that the adjustable landing gear needs to be fixed on two places that are spaced apart. The other is that the arms are the lowest part of the copter, if the adjustable landing gear is removed (many have used this option).
But neither of those reasons are very strong in my opinion and I generally don't consider this to be a good design.

The other complaint I have is that the distance between the top and bottom center plates... is very small. I cant see for the life of me why it should be. In my mind it would be good to be able to mount your equipment (HD and FPV camera, Batteries, CC, etc) between them.

The next frame I want to look at is

Michels pet 25 quad

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Although it is obviously not designed for areal photography, my engineering background just leans me towards a design like this one. The arms are over dimensional and couple probably hold a quad 10 times its weight.... However I love the idea of using plates with a large surface area and then lowering the weight by carving out of the center.
Also I like how the two plates that make up the arm are not parallel. This gives increased strength to the horizontal axis of the quad, without adding weight to the frame. Very nice design indeed.


Lastly I want to look at the turtle shaped

VC-FPV1

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The prototype that JUZ has made famous lately, with some of the most impressive shots I have ever seen, will be the last frame I tackle in this round.

This frame is designed for FPV with propellers out of view. The frame takes its shape from the camera being mounted parallel to the front two propellers. In order to keep the COG at the center of 4 motors, the battery must be pushed to the back end of the quad.

I love the flat design of this quad and I will guess that it does fairly well in windy weather. This quad is constructed very similarly to the VC-450, which is a good thing. I think it looks and operates very well.

However there are some things I would like to remedy right off the bat.

The battery is aligned lengthwise towards the front, which doesn't make sense to me. Turning it 90° horizontally will keep the same COG with less moment of inertia, making it more agile. It will lower the total length of the frame and arguably make it easier to adjust the COG.

The designers attach the front two arms very close to the camera, but the behind legs are fixed to the center of the quad. For me, this is counter intuitive to wanting to move the COG backwards.
I still feel like the top and bottom plate are too close together and the legs are bulky where they don't need to be and thin where they need to be thicker.
Why not allow the GOPRO to fit between the top and bottom plate ?

One last thing that applies to both the 450 and this one. Why have the horizontal plate so large around the motors? I get that you need spacing to stabilize the motor, but this just seems like such an overkill. I might be knit picking here... But Inserting an overly large plate directly under the motor (thus hindering air flow and reducing lift) seems so very unnecessary.


I hope I haven't bored you all to death with my ramblings. I would love feedback on this, as these are issues I am basing my design on.

Thanks for reading.



Great analysis. I would love to hear your thoughts on a totally different frame design: Mikrokopter and/or Flyduino.
I like them. They are very very simple, quite durable, and efficient.
May not be the best FPV platform, but from an engineering perspective, they are super clean.

Anyway, it might be good to have a look so you can get more examples of what people use.

Oh, and I almost forgot: http://www.multiwiicopter.com. These are some of the most beautiful frames I've ever seen.


-z
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YouMadeMeDoIt
Mar 11 2012 03:24 PM
Great frames, can't wait to see what you come up with! New to this doesn't mean you won't design a great frame. You probably have a ton of other life experience that will get the job done. Wanted to throw one of my favorites in here just in case you haven't seen it:

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Details are Here - V1.0, and Here - V2.0

Just in case it may spark any other ideas. I like that it is simple, and built around the camera. Instead of placing the camera on the quad copter, he designed the copter around the camera.

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