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.
I really like it. Especially the multiple balloon version with the rigid structure around the outside, looks very spaceshipy(for lack of a better word). I hope you get it working. It's very difficult to build a rigid structure and keep it light enough as I found out with my research.
I've done some work with something like this and have thought about concepts similar to what you're interested in trying. You can find the thread for my project here: http://diydrones.com/forum/topics/new-uav-platform-in-development-s... or you can look at it on my website as well: http://www.awkengineering.com/aerospace/uav/projectdreamchaser
I realize this is kind of an old thread, but I thought I would reply anyway as it is very interesting. Good luck if you're still pursuing it. I'm hoping to pick back up on my work in that field soon(hopefully this summer at the latest), as I'm currently working on a different UAV project that has taken precedence over this due to my job and a grant I received. When I get back to working with hybrid airship type stuff I'm hoping to do some work with an electronic variable pressure system that will allow me to reuse a weather balloon style balloon and make this process a bit more economic. That would be applicable to the expansion problem someone else in this thread mentioned if I read it all correctly. Good luck. Hope you're still working on it or some variation of it.
In the meantime a group of students in Switzerland built a similar but different concept. Even though it got 4 engines it´s not really a quadcopter. But it has an autopilot implemented and a bizarre look and flight characteristics.
It´s capable of total omnidirectional movement and turning, while mainting the position or directional flight.
Have a look here:
Rule of thumb ballast it slightly heavy. With a Quad for power you may be able to overcome the lift and bring it back down. Also, watch out for the prop wash it can potentially ruin your envelope over time, if it is constantly being buffeted.
Your project reminds me of this as well...
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.