Search results

The idea that high voltage is just magically more efficient is a myth. It's not. There are many other things you need to get right that are more important than voltage.

Seems you can pretty much do whatever you want in the US right now. The FAA has lost two important court cases which set the precedent that they don't have the authority to prevent commercial use of UAVs. Even the FAA's head council has issued a statement that people should just ignore any...

The Eurocopter X3 is actually faster than the Sikorsky X2. The coaxial rotor on the X2 presents a lot of extra drag in forward flight. An X8 is not less efficient than flat Octo. That's the main point of the presentation. The only way you can say it's less efficient, is if you constrain...

I don't know the answer to that. My guess is that, not matter what you do, you're not going to beat the efficiency of a single rotor with the same diameter as your largest propeller. Having a small propeller above or below that, could only be less efficient, I believe. Really, all that...

Yes, the added disks on a coaxial do not add disk area. You could have triple co-ax, and it would still have the same area. A co-ax is going to have many of the same characteristics of a quad with 4-bladed propellers. Basically, the solidity ratio goes up, which does increase the amount of...

Not bad. But the yaw control seems not great? Spline definitely will look better.

Wow, so Arducopter flew it with a motor out? That's cool. I haven't seen other evidence that that would work on a hex with Arducopter.

Hmmm... interesting. Thanks. I had only found this as official guidance up until now: http://www.dji.com/product/spreading-wings-s800-evo/faq Which is definitely unhelpful. I've tried several levels of tightness. From very loose, to fairly tight. Nothing seems to make a significant...

I envisage it more like... They would have a truck that would be like an aircraft carrier. It could drive down the main roads of a town, and a swarm of drones would come in and out, doing short haul delivery. Save having the trucks drive down every little road. The drones would be able to...

I've heard of them, they've been around a while. Don't know much more than that.

The worst vibration seems to be radial. Didn't do any motor balancing. Never have bothered on any motors, and don't normally have a problem (due to good vibration damping. These are KDE motors, so should be very well balanced already. Bearings are good. They run very very smooth without...

I'm not looking for the basics of vibration damping, I'm pretty skilled at that. (and that certainly doesn't include moon gel) The camera is very already fairly well vibration damped. If I could add some mass to the camera mount, put the battery up front, then it might work. But the battery...

I just finished building a Tarot 650 quad frame, and I decided to try the folding DJI 15" props. So far the machine flies quite well, but I can't get rid of the vibrations. It's bad. Worst I've ever seen. Worse than any heli I have. I've tried different amounts of tightness. No luck. I've...

I've got some very large resistor banks I could get from work, designed as braking resistors for large machinery with variable speed drives. I've been thinking of getting one, and then setting it up with a large FET, and a basic control system. This actually isn't a difficult problem to solve...

Watts (Power) = Voltage x Current. Cells x Volts/Cell x Amps Watt-Hours (Energy) = Voltage x Current-Time. Due to industry convention, LiPos are measured in milli-Amp-Hours. So divide by 1000 to get Amp-Hours. Then: Watt-Hours = Cells x Volts/Cell x Amp-Hours Obviously my spreadsheet...

I don't know. Clearly there is no industry standard. Didn't one of the more expensive brands get caught labelling some batteries at 65C, but they were really only good for 5C? I'm not even entirely sure how they come up with mAH ratings. I mean, if draining past 80% of the battery damages...

If you guys want to throw out some input on your favorite batteries, I'll see if I can add them. Just need: Name, xS ymAH, C rating, weight (excluding shipping packaging, obviously), dimensions, and price. Though the last two are technically not required, nice for comparison.

C rating doesn't affect energy density at all. Well, actually, there's a loose, inverse, correlation between C-rating and energy density. Typically, the higher the C-rating, the lower the energy density. But there's no consistency in C-rating across brands, so it's hard to say for sure. Yes...

Yeah, the 3.7V is just a nominal per/cell voltage. Could be 4.2... but industry seems to label nominal voltage as 3.7 for whatever reason. Doesn't really matter as long as you use the same number across all batteries. Also, could use mAH/gram, but Watts allows you to compare energy density...

Wow, from a little Phantom. Amazing. You could definitely be in trouble if you got that in the neck. I've been wondering if textile motorcycle jackets would work well enough.