I have decided that although i could probably cobble together a vehicle relatively quickly i would like to make it as professional as possible. I had started a 3d drawing of the vehicle bu decided it to be unnecessary. It would help in determining the weights of the structure but i think the simplest thing to do is to just build it.
I am planing on building a prototype first, and then a proper vehicle. This may not be nessicary but i do not think i will get everything (weight distribution in particular) right the first time. When i tried to make the first compressed air airframe i had a hard time making all the frame square, this could also be an issue. I may have to make some sort of jig to hold the pieces in place while i drill and rivet them together.
As for the shape of the airframe i am currently thinking about a simple rectangular prism. A cylinder would be nice aesthetically and also more rocket like but with the shape but the way i plan on building the gimbaling mechanism its not really possible. Layers of perspex of aluminum plate joined together with welded rod are temptingly simple, but i from my first attempt of building the frame a rivited frame would be more rigid.
The gimbal will be just like one of those gyroscope toys:
Accept on one end of each joint will be a servo and there will be a ducted fan where the spinning mass is. Also instead of being circular it will be square.
One issue i just considered is that there will be extra force from resisting the spinning mass of motor shaft and impeller, hopefully the servos should be powerful enough.
I am not fully aware of the isues with response time etc, but just from thinking about it i can imagine that a brush less engine and servos will have a better response time than moving/changing the thrust of a bi-propellant rocket engine, although for the engine it does not matter that it is producing more thrust than it needs to hover, as we will need to speed up the engine when we thrust vector just to stay level. I ordered digital servos as they were not much more and from my reading they seem to be more accurate. I am considering the possibility of gearing down the servo at present i believe they can traven from -180 to +180 digrees. This amount of movement is not required and if i could gear them down i would have more accuracy.
Charging batteries could be a minor annoyance as we are using three battery packs and the charger i purchased only charges one at a time. I imagine it would take about 30-45 minutes to charge one pack. This may become a constraint during later development of software but initially i imagine we will only do small runs.
I am feeling good about the project at the moment but i haven't started building anything! I have a tendency of half finishing projects, so i am a but anxious to prove to myself that i can see this one through. The goal is a completely autonomous hovering robot that is as rocket like as posible, capable of moving between two points in space reliably. Dont forget that! I think if i work steadily i should be fine. The temptation to quit will be when i build the first prototype that semi works (perhaps in one axis), but i will be disappointed with myself if this happens.
Also sorry for anyone who is reading this! i can only imagine what you are going through..... I will try in future posts to make it more readable and understandable (with pictures). I have trouble expressing my thoughts into words.
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