Koifly - electric harness for hang gliders 

Thanks, I hope that making this system available will help some people stay in the sport, and maybe even bring new people in. I don't know, maybe that's just wishful thinking... but we could really use a resurgence in hang gliding right about now, before all the remaining old timers retire.

Thanks, love your videos! I hope that I will actually be able to make these for other people. As you can imagine, selling this kind of novel design commercially is a liability nightmare, especially here in North America. I really want to make it work somehow though. If anyone has any insight or advice on this kind of thing, I am all ears, see my email on koifly.com

@@koifly Thank you for the compliment. I'll drop you an email.

Hi Rol, sure, will be happy to help any way I can with that! Perhaps my system could even be adapted to your aircraft, we'll see. Your wing's low drag could be quite beneficial performance-wise.

Please see all my other comments here and in the "ePowered hang gliders" Facebook group. If you want flatland launch, I don't think such a small prop would be enough.

@@koifly I am also planning to use Robert Berndes style twin motor downtube control frame setup (if you see his dual motor setup where he takesoff flat land zero wind) 10 kw motor X two. or less 7kw motor X two Prop 27 or 30, etc hope it works .I feel side motors better then tail also battery safety but cost increase of all components, motor sync speed thrust , etc Please post more videos of your making enjoying it Thanks

Weight is 20 kg for the whole system that attaches to your harness, including batteries. With some adjustments to the hardware and software, I could potentially use any battery that can deliver enough current and have good enough energy density. Right now, commercially available Sodium-ion cells are no good at either of these. As for solid state - sounds promising, but I'll believe it when I'm holding one in my hands :) Hopefully some day.

Not right now, but eventually, soon-ish - it's still rather unpolished at the moment. Please fill out the survey on koifly.com with all the details, and indicate that you would like to test.

Thanks! Of course, see my email on koifly.com

Aside from other issues, you need ~10KW for a good confident take off, and no less than 3KW for maintaining altitude.

@@koifly Several human power aircraft were tested over history, with some of them reaching more than 100 km of distance, taking into account that humans can delivery a max of 1000W over short periods (take off) or 300 watts on longer periods (cruise). Of course that requires larger wings and quite light structures. But hand gliders are quite light too. I know that my power numbers are very optimistic, but yours are not optimized either. In your case your prop is too small, those are good for speed, but not for efficient thrust. I guess something in between could be achievable, like 2000W for Cruise and 5000W for take off, besides my power calculation of 1000W using Solar Cells was using just 5 m2, but most hand gliders have 15m2, this mean 3000W. A battery can provide the take off power.

@@angellestat2730 Well, you asked specifically about solar panels on delta wings, so I told you my numbers on said delta wings. My design choices, including the size of the propeller are the result of a complex optimization problem that concerns not only raw power output, but also weight, costs, handling, etc. It's not really possible to "just change this one thing" because it will result in a cascade of many other things that now need to be different - and they all could be heavier, more expensive, or degrade handling. Using solar panels on flexible delta wings is not straightforward. You suggested using cheap PV panels, but how much do these actually cost, how much do they weigh, how much power do they produce (not at noon in California, but in other times and places too), and are they light / flexible / durable enough to mount on our flexible wings, and is it possible to somehow wrap them up for storage. There's a lot of hype about solar panels, but to actually experiment with them, you need to actually buy those panels at some point. And there's a significant difference between technologies that show up in the news yet only exist in a lab, vs an actual component that I can see the specs of, and buy, to experiment with. I have not seen any actual purchasable solar panel components that would have good enough specs for use on hang gliders. I will be happy to be proven wrong about that, but I will not be convinced without specific data sheets and price lists. Press releases alone don't count. Of course, if you don't constrain yourself to hang gliders, and don't care much for the aircraft complexity, size, costs, etc. - then you will find some existing designs that do use solar panels, for example the various SunSeeker sailplane designs. As for human powered aircraft - their wing span is completely impractical for recreational flying, and they only have barely enough structural integrity to fly in calm morning air. By the time you adapt their design to make any other use case possible, the aircraft will look, fly, and weight more like a traditional sailplane, with the corresponding power requirements.

​@@koifly look, I was just looking for an interesting discussion about the possibilities of what can be achievable (maybe not for me, not for you, but for a company with certain budget). I show you how there is a whole world of possibilities between your 3000W vs 300W for cruise. But in your mind, there is nothing in between. I understand, you are in selling mode. So I wish you good luck with your setting and sales.

@@angellestat2730 That's not what I'm doing, and not what I'm saying. I am not in "selling" mode. Posting one video four months ago isn't much of selling. I am in building mode. I've done the research and I've done the math, I know what's currently possible and at which tradeoffs, and now having built a series of prototypes, I have actual numbers that confirm my prior analysis, so that's what I can share confidently. I am not saying that there is nothing between 3000W and 300W cruise. Closer to the 3000W side are flex wing and rigid wing hang gliders, and farther down are microlift gliders, sailplanes, etc. I even gave you examples of actually existing solar powered sailplanes. I'm not sure why you don't like that answer. It accurately reflects reality. As a builder, I work in the reality of things that exist, not in some potential future reality that the endless press releases from various companies and universities promise us (but rarely deliver outside of the lab). It's fine to talk about the potential possibilities in the future, as long as you understand that those are just potential futures, not the current reality. Maybe someone will invent a more efficient hang glider that only needs e.g. 1500W for cruise. Maybe the PV cells suitable for our use will become commercially available. That might happen eventually, but it hasn't happened yet. But when you ask "why hasn't anybody done this yet", you yourself are putting the conversation into the present reality - because that is where this hasn't been done. I honestly don't have much to say about the future. Batteries, motors, solar panels, structural materials - everything will be better and cheaper in the future. But we're moving into that future very slowly. All the components and materials available to me today are pretty much the same as the ones that existed a few years ago. Li-ion chemistry has seen incremental improvements in that time, but nothing earth shattering. Will be nice when we get those promised 500Wh Li-ion cells. But as it is, they aren't even used in real cars yet, let alone sold commercially, meanwhile I want to fly this thing now, and have to focus on what I can actually get. I'll welcome all that new tech with open arms once it actually materializes.

@@JoshuaWriter Heyo, sorry to keep yall waiting, I've been busy designing and implementing various upgrades, from electronics to the power components to new manufacturing processes. Haven't had the time to do a proper update in the meantime. I will post another video some time this year when I cross over the finish line with some of the most important upgrades. Working hard to make that happen as soon as possible. Cheers

@@koifly Just do an update, about the upcoming update... We don't need perfection. Would be cool to see what your planning ...