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I can imagine it using one of those Rotec Radial engines high HP and low weight. And probably not much more than the battery and electric motor weight over all. https://www.rotecaerosport.com/
Will the infamous "flying car" finally have its day?
- Thread starter cmartinez
- Start date
I can imagine it using one of those Rotec Radial engines high HP and low weight. And probably not much more than the battery and electric motor weight over all. https://www.rotecaerosport.com/
Hello,
@shortbus , That site has some weird motorcycle projects:
https://www.rotecaerosport.com/motorcycles
Bertus
@shortbus , That site has some weird motorcycle projects:
https://www.rotecaerosport.com/motorcycles
Bertus
Nice! those engines are almost as old as aviation itself... I would've thought you'd prefer the wankel type of engine instead.
The motorcycle stuff is how I learned about those engines being available. Saw a couple of builds people did.
I was interested in the Wankel but couldn't find one in any of the local junkyards. The earlier ones like the Mazda's used were really heavy and had lobe seal problems, also had problems meeting emission regulations.
If trying to do one of these with an IC engine, I'd use it to drive a hydraulic pump and then hydraulic motors to drive the props. Like in a zero turn lawn mower. Doing it like that would save on power transmission ,no gear boxes to keep the counter rotating props on each corner. Just two hydraulic motors that probably are close in weight to the electric motors.
and also, said hydraulic motors would probably have the same response time as the electric ones, wouldn't they? I mean, controlling their speed and torque would be much easier than directly using IC engines .... OTH, what about using a small turbine instead of an IC engine?
I did, a few days ago when this vehicle took over my youtube feed. Cost $92k USD and has a flight time of 15 minutes. Cool to look at, probably cool to fly too.. but not for long. It does 67mph I think, so that works out to a range of 17 miles. For $120k USD you can get the world's cheapest helicopter which is a two seater with 460 mile range, top speed of 155mph, and fly it up to 2,000ft while running on pump gas.
I really think that you could build a quadcopter like this using a rotax engine and some kind of clever geartrain to eliminate the need for electric motors, and have something much cooler.
The only problem with a turbine, like they use in a helicopter or Abrams tank is they are either on or off, and use a CVT transmission to change speeds. Some people use them in Tractor pull tractors without the transmission because of the weight but they don't do so well, they break the tires loose and don't get traction.
I think hydraulics would work, but there are several drawbacks. Horrid efficiency, heavy weight, hope you don't spring a leak in flight. I think a system of rotary shafts and small CVTs would be a better bet
Looks like an abortion lol or a pregnant motorcycle take your pick. Upright V twin is far more appealing to me, just saying, not into the inline, Bullet vs Twin, sounds and looks different. Now a Rotary that is interesting, never heard of it, I enjoyed the Diesel versions in Europe, smelly though can only imagine, but also a work horse.
kv
How about keep the electric motors, but use a gas turbine as a power generator?
I don't know a whole lot about gas turbines but since you seem pretty sold on them I'll make the assumption that they produce a lot of power in a small package, efficiently. That assumption made, I still don't see the advantage of making it a hybrid electric system. Conversion of mechanical to electrical and back to mechanical is going to eat into the overall efficiency in a big way. IMO mechanical power should be transmitted in the most direct way possible straight from the prime mover to the propellers, regardless of what the prime mover is, not just for the sake of efficiency but for robustness, reliability. What would be gained by going hybrid? As the craft is expending constant energy to stay aloft, I don't see any opportunity for regenerative braking or anything.
Earlier I suggested CVTs at the propellers. After some thought, I believe a better idea is the variable pitch propeller, which if I'm not mistaken is what helicopters already use. I believe that would offer the same near-instantaneous changes in thrust that quadcopters are famous for, and allow for the mechanical drive train to be very simple, and run at a more or less constant speed. Imagine a 4WD/AWD car drivetrain, but with simpler gearboxes instead of differentials.
On 6th thought, a vertical shaft engine with timing belt drive directly from the motor shaft to propeller shafts would be probably more efficient than rotating drive shafts and gearboxes. Do they make vertical shaft gas turbines? If so, that's my vote. Vertical shaft gas turbine directly driving variable pitch propellers via timing belts.
Reason 428 for no flying cars. The fracking noise.
Imagine that crap flying over your nice house every day and every night. Flying cars will also need to extremely quiet.
I may have seen it wrong in the opening video posted here, but to me it looked like each corner has 2 props, an upper and lower and counter rotating to lower torque thrust. https://en.wikipedia.org/wiki/Counter-rotating_propellers So that would take some sort of gear, not a belt or chain to make them counter rotate.
From what I understand about turbo shaft engines or even turbo jet engines, they don't worry about how they are mounted, horizontal or vertical. It is just easier to package them like in a plane, helicopter or a tank being horizontal.
Yet another vehicle is about to hit the market ... I hope this is not a passing fad:
