Now I'm really confused !

[flyer88]

OK, I've just spent hours running prop tests on my Nexstar electric and have come up with some confusing data.

I set up the test with Tach, watt meter, and an assortment of props that I intended on logging data with.

I've been running Master air screw GF Series prop (11 x 9) which is a nitro 4 stroke prop. It has given me highest efficiency numbers out of all the other props I've tested. I'm not just talking a minor difference but a significant reduction in amp draw, while still producing great thrust. Most of the other were electric props from APC, Master Air Screw and a nitro prop from Evolution.

For the life of me I can't figure out how it's more efficient ? Not to mention it's super easy to balance, having a square tip which you can just grind down versus a profiled APC type prop.

Any suggestions ?

[flydiver]

Did you do actual thrust tests?
Efficiency means power in vs. power out. If you only are reading power out via wattmeter you aren't really measuring efficiency just how much a particular prop using a particular battery draws.

You also need to be careful about KIND of prop, not just make. APCe is NOT the same as APC-SF by a LONG shot.
Thin straight blades will draw less, sometimes a lOT less than a fat SF prop. MAS tend to be thin and straight > likely less draw, but also probably less thrust.

The wattmeter lets you know what you CAN fly without killing your motor/battery/ESC. You have to actually FLY them to figure out what you and that particular plane like.

FWIW the MOST efficient prop is not something most people would fly. The most efficient speed for your car is around 45MPH. Do you drive it that way?

Example-
Buddy came over with a plane and a box of props. We did wattmeter and thrust tests on a bunch. I proved to him with numbers that a particular GWS prop got more thrust with less amp draw than his beloved APC-SF. He tried it but has always used APC-SF and didn't like it. He can't get it that 2/3 throttle on a more efficient prop is using less of his battery than 1/2 throttle on the SF.
This is in spite of the numbers staring at him. And the GWS-HD flies differently than the APC-SF, more thrust, but, at the cost of eating more power. Nothing is free.

How did you manage to put HC props up there (most of them pretty raw, out of balance and generally ugh) and not GWS?
GWS SF are pretty lame props except for REALLY slow turning motors (geared) but the DD are great.

Because it does not differentiate between types of prop as well as brands I don't think the poll will be very useful.

[duck9191]

i ran a MAS 10x8 on my cub for a while, and the amp draw was a bit less but the lack in thrust was very noticeable. APC-E always worked wonders for me as amp draw wasn't a concern so i was just worried about thrust.

i haven't had to bad of luck with the hobbycity props, ya they do need to be balanced but so far have worked great. they have some very nice wood props to but they are on a gasser.

[flyer88]

Me too. The HC props seem to be ok. I can't say I put anymore effort into balancing them then any other ?

One prop I was very disappointed in was the new Evolution line of props, I had to add a ton of clear nail polish to get it to balance.

Glenn

[flydiver]

Are you talking the black SF HC props or the ones that look like APCe clones?
I find the black one's terrible. I bought them several months ago so it's possible they've improved.

[duck9191]

the ones I have used are the "TP" apc look alikes. I haven't tried the sf props yet, I'll have to throw a few on my next order to show bad they are.

[flydiver]

The TP/APCe are quite a bit better.
The black seem to pretty much APC-SF type clones. Very bad balance, blades and hub. I use nail polish to balance and it often takes 5+ coats, some full length, and as much as I can be bothered to put on the hub.

[mrmugen]

Why add? I have always sanded the heavy side with good results.

Curious,
Kevin

[duck9191]

if I am in a hurry or at the field I use thin CA, but if have time to ill sand it instead. wood props I sand either way.

[flydiver]

Sanding removes material and can change the flex characteristics if more than a little is removed. This could possibly lead to a balanced prop that is dynamically flawed.
On 'good' props it may not be an issue. On poorly balanced ones it might be.
I'd worry on GWS-SF those are so thin and floppy anyway. OTOH you best not be turning them very fast.

Besides, it's just easier to paint on some clear nail polish.

[ginginho]

Pah, when did the poll get added, and why ain't GWS DD/HD's an option. I fly em (as do a few others I believe) and think they are the dogs dangly bits. FWIW I think APCe's are too brittle.