Hi.
I am very interested in e-ppg flying and Voltair looks great.
I like the idea of mounting only 2 batteries for total lightweight and to take off from a hill and to use in free-flight, and just in case I need some extra power ( low wind ) to keep flight level to reach a desired landing field.
But the cage, and the propellers produce a very big drag in flight, so I was asking myself; What if I fly without the cage and folding props? That would propably reduce the drag a lot and help for better flight performance.
I don’t think the cage is necesary for protection during take off because you only turn power on when the wing is on top of you already inflated, and during flight the same. And when landing, if you turn power off just before touching the ground no problem with lines either…
What do you guys think?
well, if you reverse launch, you are right, it will work also without a cage.
However if you do a forward launch, the lines will get caught right away by the two lower arms/motors/props!
Also: If I have the option to launch from a hill side, I would not use the OpenPPG. Why? because I can use the elevated hill to launch from.
Should I not make it to the landing zone, I’d land elsewhere and walk back (happened a couple of times already to me).
I am going to use the OpenPPG to launch from the ground near my house, for either a short (20 minutes) flight, or to get into the thermals.
The motors on this design are pretty close to your body. It’s easy to touch the net with your elbow and it’s a gentle reminder not to press your elbow back any further since the net isn’t very far from the propellers. Also, the throttle cable is continually blown back against the net and I do not have excessive length in my cable.
We’ve been doing forward launches with snow skis and noticed the net stopping the lower paraglider lines from getting sucked into the prop. With a normal forward launch your lines should be tight before throttle up but with skis we need the thrust to push us forward.
You would only have to hit a decent thermal for the wing to partially collapse thus causing the lines to go slack for a moment. If that happened one of those lines could foul a prop. Imagine what effect on the wing it would have if any one of the lines were wound in by being winched on a turning motor. That actually happened to a guy here in Oz. Granted it was a petrol motor and standard PPG setup but the point is his wing was wound into the prop within a split second and he spiralled to his death.
What about a hoop and 4 smaller nets/cages? Slightly more complex but less drag, and the same safety level.
Or (this might be an entirely separate topic) a thrust tube? I’ve seen them in marine applications and they increase the efficiency of a prop in water by redirecting the flow which would otherwise go outwards away from the prop. Has anyone tried this with any success in droning? Seems to me like a way to (1) protect the prop and pilot and (2) increase efficiency.
What you are talking about is a ducted fan. That concept has been discussed several times on this forum and has always been shot down by people with experience. Type ducted in the search of this forum and you can research it more. Here is a link to one thread: