VTOL newbie

[twiglet]

Hi im interested in getting into VTOL aircraft as normall RC has sort of lost its apeal to me im after something a little more challenging now.

Ive got a few ideas for designs mainly something that looks similar to the small hunter killer in treminator 3 (three props/turbines one at the back two at the front), im also hoping for it to have some load carrying capacity.

Im basicly just after any advice you can give to me before i start and guide me away from making any big cockups.

Thanks in advance.

[Unconventional]

I like the concept of the T3 Hunter-Killer - probably never been done before. In the movie it was completely animated.

I found that to start from scratch as you want to do, I had to start with a known quantity: thrust. If you go electric here is what I would recommend:

1. Pick a motor / prop combo with some published thrust values. You can start by getting a copy of MotoCalc8 at http://www.motocalc.com/motodown.htm This will help you choose from almost every available battery / motor / prop combination. It also predicts performance for conventional flying based on power available, wing loading, etc. Since I found that it was very easy to exceed 2-3 lbs when prototyping (4 rotors, 40amps), I recommend going with an option that can put out 4-6 lbs of thrust. Although 15% more thrust is the minimum, you will want to shoot for 50% - 100% more thrust for a reasonably responsive VTOL.

2. Order / test your choices on a static thrust stand! Make sure you can get the published thrust values / durations which may be overly optimistic. You will have to build a test stand which isn't difficult, but do a search for this since many have gone before you. Use all the components that you want to have on your prototype: battery (probably batteries), ESCs, radio, motor and prop components. This will eliminate surprises when you integrate everything into your model.

3. Design for low weight, high strength and plan for stability problems. For example, if you don't use counter-rotating props (which you can't find for ducted fans) you will have a strong yaw component to correct. You will also need some automatic pitch and roll correction. Go with some good gyros or autopilots. I am building my own, but only because it is a learning experience. Since stability problems are evident only after the VTOL leaves the ground, this has been the most challenging stage for me.

4. Once you have chosen all your power components, build the prototype around them. Of course, your design should accomodate any adjustments you will need to make for motor mount angles, wing width, weight and balance, etc. I started with a plywood prototype but will be designing the next fuselage out of carbon fiber rods. This will make it lighter and stronger, but requires much more design / development time.

5. Once it will hover, the next step is to get it to transition to/from horizontal flight. I have no experience with this yet but I'll let you know. :-)

Good luck...

[twiglet]

Cheers most helpfull, i would imagine there is a lot of trial and error involved too butit should be fun.

[twiglet]

Sorry to bug you all again but i just saw something on the TV about UFO's and they showed that strange triangle shapped model made of foil and balsa wood does anyone know the name of it and i think it had a website to, im sorry i dont know very much about it apart from the fact that no one knows why it flies and is triangle shapped.

[Flipper_118]

Thems are called Lifters I do believe,
They use a high voltage source between a very thin wire and the foil that you saw. I am fairly sure they are lifted by ionic wind created by the HV potential between the wire and foil.

Run a search on lifters and I think you will be overwelmed with the amount of information.

Curt