manolis wrote: ↑
Fri Apr 17, 2020 10:42 am
Βy the way, did you get what problem /asymmetry Rodak sees in case the one engine of the Portable Flyer stalls?
As he says, it has nothing to do with lack of power, but with controllability.
Yes. I would recommend to make a list of all possible failure modes and if and how they are recoverable or what the "Plan B" would be. Just as an example, what if only one belt rips? It would generates asymetrical torque, wouldn't it. What if you hit something which damages both rotors on one side? which is quite likely to happen with such a setup You would have asymetrical lift which you can't recover.
Than an other thing. If i would hover in 5 or 10m hight and one engine seizes, does the other one automatically increase power or would i have to do this myself, in which case it's highly likely that i have not enough time to assess the situation and react to it before i come crushing down, with one pair of rotors still spinning which generates a chance to injure me further or even kill me.
How heavy is somebody allowed to be, that one of your engine can keep him in the air? And i don't wanna know what other engines can achieve, what do you think your engine can do? I'm a a bit on the fat side so i don't think i'm ideal anyway, but remember, an average european male is over 80kg in underpants.
Hanging in a 6 point harness isn't exactly comfortable, especially for men. So i hope you have a solution that wouldn't cut the blood flow to the testicals for your proposed up to 2 hours flight time.
And one more thing. You came up with the "pendulum rocket fallacy". But you didn't seem to notice, that your construction has exactly the same problem. Center of lift is above center of gravity, right? So what if, i can't bring the center gravity excatly under the center of lift for what ever reason?
if you tilt your rotorsystem to compensate for that, you induce a lateral movement. So basically, your personal flyer can't properly hover if the CoG isn't exactly under the CoL. And let me guess, do you plan to store the Fuel in a backpack? What do you think where the CoG goes when you attach a 20kg backpack to the person hanging under your flyer?
Edit: a Good demonstration i think is a shuttle start. If you look closely, you can see that a shuttle moves several meters lateraly in the first few second, just because the center of thrust is not alligned verticaly with its center of gravity.
You can use your mouse curser as a refrence, the camera is on a gimbal, but it doesn't move in the first few seconds.
Just a few points you really should consider.