What a great tool. I’ve used it for years and I can’t believe it’s $8 a YEAR for just one tool. Saved me so much time that it payed for itself 20 times over.
Something I'm curious about is how one of the standouts in the market for efficiency and endurance, the STRIX Nano Goblin, gets away with its motor and prop setup. It runs a 1606 4000KV motor and a Gemfan 3 blade 3052, in a pusher configuration. Even with a 2S Li-ion pack that's still significantly higher RPM than other planes. It would seem to be doing everything wrong for efficiency and noise: high KV, small diameter prop, extra blades, pusher configuration. Yet it's widely considered one of the quietest and most efficient platforms on the market. What gives?
My guess is that it isn't actually very efficient. It gets long flight times because it has a Li-ion battery that is way bigger than the batteries on most planes that size. If such a battery were used on a tractor motor glider with a large prop and a low KV motor, I think the flight times would be even better.
I've personally been making my first wing. Enjoy comunity.. in my quest for knowledge. Not many videos on Props.. motors.. direction and size and why'.. thanks! Wings in general. Coming from quad's. Didn't even know push only props.. can you use any prop for a Wing? As long as installed right. ??
You can but some props will work well with some motors. You tend to find that there is more of an eye on static thrust for MR props and a greater balance in FW props as it is the wings that create the lift.. See the other video in the series..
Assume you have a Pull propeller on a motor on front of the aircraft. Now move this motor to the back of the aircraft and change the motor rotation: will the motor/propeller work as a Push type?
I use the cheating method of choosing a prop & motor, by following the recommendations of the manufacturer, though it can be confusing. I’m preparing to work on a new model, that recommends a 2216 900-1000kv motor, 20A ESC, & 8’- 9’ prop. I use a 2216/ 960kv motor & 45A ESC combo in another model and it works beautifully with a 10 x 5 prop. So I purchased this again for my new plane, with a 8.25 x 5.5 prop (9’ prop wasn’t available). The manufacturer of the motor/ESC recommend a 10 x 5 to 12 x 6 prop. So the intended prop is smaller than recommended for the motor, I have spare 10 x 5 props but they’re larger than recommended for the model. This plane is a WW1 scale model so I’m hoping that if I stick with the smaller prop, that it will fly well in a scale manner. Can you foresee any problems?
So what about situations where you have something like a 6.5x14 on a goblin? Am I going to have to catapult launch it? I have tested it once so far and it did not go well at all. It would be cool if you could just touch on some of the more exotic stuff to give us adventurous builders a building block to start with. Ecalc is great but I haven't had much luck trying to figure this one out... My membership also needs renewed 😬
Launch is all about static thrust. If the setup you have is tricky to launch then you need more than what your existing setup is giving you... Best of luck
Lee, One question that I have about eCalc is about the ability to save a configuration. Over the years this has been my biggest trouble, is that every time I pull up the program I have to re enter information for every setup I want to test. This can be inconvenient when working on multiple projects. Is there an existing way to save setups, or is there an alternate reason that Pawel has not added this feature? I know this video is a little older, but I hope that you still see this response.
The 66% Rule doesn't seem to apply to Big-Quads ......... My best calculations based off of T-Motor's Spec-Sheets, ( for a huge Camera Platform), seems to be more like Diameter X 30% = highest efficiency. 21" X 6.3" Pitch at "Hover-Power". ( 1451.5 - Grams of Static-Thrust per Motor/Prop Combo ). Top-Speed is not a priority, but Maximum-Thrust is still over 3X Hover-Thrust. ~48-Volts X ~15-Amps Max. . . .
I think this needs discussing in the next video (if we get enough interest). Another example I mention in the video is that smaller 5x5 props are not a bad choice for things like the AtomRC Dolphin but according to eCalc they will stall... Happy flying
Hi Jim, the 66% rule is NOT for best efficiency. It is a rule of thumb where the laminar air flow over the blade stards to get turbulent. e.g. if you in crease the pitch of an 18“ prop byond 12“ the propeller blade tends to stall in static conditions.
Does speccing a lower TWR prop and motor combination give a produce a noticeably more efficient vehicle, and if so what's a good minimum TWR? RC planes tend to have TWRs above 1, but in larger scale aviation you see significantly lower TWRs across the board, from a 737 (~0.3) to a Cessna 172 (~0.25), and only fuel guzzling fighter jets go for TWR >1.
