My initial vision started with a disc like membrane that held the 'lighter-than-air' gas directly in the center of this blimpcopter - disc shape for an aerodynamic body.
I than protruded four bars from this disc (about the length of the disc's largest radius) to have the motor and propeller attached at each end (quadcopters style)
The blimpcopter works by having a (balanced/close to balanced) lift-to-weight ratio. a.k.a the lifting gas provides enough lift for at least the following basics:
- Disc membrane
- Motor x4
- Propellers x4
- And of course autopilot
The four motors can either provide enough lift to accommodate the negative balance to achieve flight or if a full balanced craft is constructed the four motors will only need to be turned on when in-flight direction/speed change is needed. This blimpcopter will hopefully combine the positives of known aircrafts; which is long duration flights (perfect for surveillance, poor man’s satellite and monitoring) and power, speed and control.
Blimpcopter = Primitive Flying Saucer???
This is what I have so far:
I am currently designing a couple of prototypes in both AutoCAD and Catia. The disc membrane is most likely be constructed using a weather balloon 8' in diameter. Roughly 7500 Liters of helium will be used and give us a total of 15-17lbs of playing field.
The disc shape could be made by using a small PVC pipe wrapped to make a circle (hula-hoop) and placed on top of the weather balloon. Lightweight rope/string will then be attached at 4 points on the top circle and pulled down to the 4 quadcopters-bars which would have to be mounted under the weather balloon to provide the clamping we need on the weather balloon to make the disc shape.
Electronics/battery would have to be mounted under the four quadcopters-bars.
Other prototypes include using 4 smaller weather balloons that will straddle two long intersecting bars with the quadcopters set-up on each end of the bars.
Any feedback/research/help brought forward would be perfect, if you guys have seen or heard anything like this please send me a link I would looooove to see how it is done.
Please keep in mind that the helium will act like any other gas: When heated by sunshine it expands, and provides extra lift. Danger is you not being able to get the whole thing back to ground with the extra lift or even the balloon popping form the stress of the expanded helium.
Other than that I personally do not believe in this kind of hybrid.
Ballast tanks would not be a bad idea. It would be better to have the thing too heavy sitting on the ground than to have the motors stop and you still climb climb climb.
OR maybe you could figure out a way to get the motors to run in reverse as a fail safe? (this seems like it would take some programing, though)
That's also why I mentioned not to zero out the weight with the helium.
I think Proto 3 looks the most promising. Will you be writing custom ACM code for this?
Acm code ?
proto 3 was one of my first designs, I will be saving it for a phase 2 of prototyping - advance structure and multi-balloon framework. With my first protoype I just want to accomplish placing 4 propellers at the horizon of a weather balloon with all components working and a close to full balance lift-weight. First with a spherical balloon and the next step would be to compress it.
Proto 1 is going to be my first attempt and I plan on running the following tests:
- Motor balance
- Payload/lift capabilities w/ and w/o motors
- Vert speed / horizontal speed / descent speed
- Total flight time
- Flight in select wind conditions
- battery life
I hope that proto-1 will be able to answer a few questions I have with just some of the above tests.
I have no experience coding for somethign like this, I will most likely be using whatever is available.
I'm still trying to find out what electrical set-up I would need to run four of these bad boys
I don't think you would have to buy expensive motors for this project since you won't have much weight. You can probably find cheaper motors that still take large props.
As for the code, if you keep it so there is still a little bit of weight (200 grams or so) so the thing doesn't float off you could probably use the AC2 code and adjust the PIDs.
I am not sure what kind of motors to look into or prop sizes. I'm thinking between 2-3' diameter for the props.
Planning the perfect set-up is going to be difficult...