Props, props, and more props

R

RTRyder

Merlin of Multirotors
This afternoon I got a chance to try out the Hoverfly quad with the 11 x 4.7 APC props on it and as expected they do generate a lot more lift, I was hovering a little below 1/2 throttle instead of the just slightly above when fully loaded on the 10 x 5 Graupners. It flew fine, the extra inch of prop length didn't seem to bother the motors so it appears they can handle it though it would probably be better with lower KV motors so they spin a little slower.

Big difference came in when a gust of wind hit it, the extra lift has a much greater effect on the quad when it's windy, bounces all over the place where it only had a little twitch to it with the smaller props so I think these are too much for the quad without adding some weight to keep it stable. Good to know I can up the prop size that much if I do need to lift more payload though.

Just as I got done with that I got an email notification that the 11 x 5 Graupners I've been waiting for are back in inventory, figures, I just bought the APC 11 x 5 set because it looked like it was going to be a while before the Graupners would be available and as soon as I got the APC in hand the Graupners show up. I immediately went to the website and ordered the 11 x 5's with plenty of spares, I can't wait to try them on both the Hexa and Hoverfly.

The Graupners have a very different blade profile than the APC so I think they will work out on the quad, on the Hexa I need the extra lift as right now it's very much at the limit of what it can lift on the 10 x 5 props.

So now I'll have a bunch of the Graupner 10 x 5, a set of APC 11 x 4.7 plus a couple spares, and a full set of Graupner 11 x 5 plus spares, looks like I'm set for the season on props now.

Speaking of the Hexa, I just checked tracking and found the new flight controller board is out for delivery, fantastic since I only ordered it two days ago and the weather between here and where it's coming from is crap right now. The USPS delivers the goods as promised! :)

Ken
 




R

RTRyder

Merlin of Multirotors
According to their website they still have 11 x 5 right and left in stock, that's all I bought this time, I've got plenty of 10 x 5's on hand already :D

Ken
 

D

DennyR

Active Member
Ken
I did a little testing of props this week and found some interesting things. The 14x4.7 does produce the best lift efficiency on the MK3538 motor on a test rig. BUT it does make the model very sensitive in throttle response. I did my tests on a small Minsoo Kim Quad with the 3538's fitted. Way overpowered but the idea was to gradually increase the payload and see what props worked best. In the lightest possible configuration it was almost unflyable due to the oversensitive throttle, however by cutting the 14x4.7 down to 11.5 dia. it was flying really well. So the fact is that you can have too much prop efficiency. As the weight got higher, so the increase in prop diameter improved the response. But even at very high payloads the full 14 dia was still too much.

I also tested the APC 13x6.5 and found that the pitch is too high at any dia. It was way down on endurance due to being very inefficient. It produces a lot of noise which indicates that it is stalling most of the time.
 


R

RTRyder

Merlin of Multirotors
The Graupner 11 x 5 props arrived today, twelve days from shipment in the UK to my front door, I guess they didn't go airmail!

Got a set mounted on the Hexa before it got dark and managed a short hop out in front of the house, wasn't enough to really notice much difference so far. Friday is supposed to hit temps in the 50's, I may take a long lunch break and see if I can sneak over to a nearby baseball field and get in a test flight or two.

I will say the parameter setting changes have made a world of difference in stability on the Hexa, it was gusting pretty good out there and it held position really well, have to wait and see how it does in regular flight.

Ken
 


R

RTRyder

Merlin of Multirotors
Got a chance to fly the Hexa with the new props at lunch time today, set the TX timer for 8 minutes and flew it around, tried out GPS hold, Altitude hold, and both at once. Seems to be working pretty good, motors were just barely warm at the end of the flight as were the batteries, I put back 3300 mA into each 5000mAh pack once they cooled down. If I get a chance tomorrow I'll swap back to the 10 inch Graupners and do the same flight to see how the battery usage compares.

Looking at the video out of the GoPro from the flight, I've still got some work to do dialing in the camera mount.

Ken
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
ken,
new graupners and spacers are finally all here and ready to go. i'm thinking a little thin CA glue at the base of the prop would be a good idea to lock the spacers to the props to keep things from spinning free under load. any opinion on that?
thanks,
bart
 

R

RTRyder

Merlin of Multirotors
Bart in NJ said:
ken,
new graupners and spacers are finally all here and ready to go. i'm thinking a little thin CA glue at the base of the prop would be a good idea to lock the spacers to the props to keep things from spinning free under load. any opinion on that?
thanks,
bart
Click to expand...

So you've probably noticed the spacers are longer than the prop hub is thick, glue is not the answer here. It's a bit of a PITA, but what I do is take a file and carefully bring the spacer down to the same thickness as the hub, once you do that you can tighten the prop nut down on the washer (you do have the large hub sized washers that go between the nut and prop don't you?) and the prop will be nice and snug on the adaptor. All the spacer does is keep the prop centered on the spindle, it has nothing to do with keeping the prop from spinning on the adaptor, so file the spacers and if you don't have the proper washers to go on top of the prop you shouldn't fly until you get some, it's really the only way to make sure the prop is secure and won't slip on the shaft.

Another reason I never glue the spacer is if you break a prop the spacer can easily be popped out and used in the replacement.

Ken
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
too late. i don't have the prop washers you're talking about, only star washers to use as lock nuts. they don't cover much beyond the spacers so i glued the spacers. i'm going to order more of everything as soon as i get a fix on which props i like best. xoars should be here in a few weeks hopefully with a 5mm prop bore already taken care of at the factory. i requested it, we'll see if i get it.
flying is almost certain tomorrow with the okto/camera combo. wish me luck.
bart
 

B

baker55

Member
I'm using the stock props APC 12" that my hexa kit came with. They seem to work well but I don't have anything to compare them with. If I ever get my camera mount I will be lifting a 7D so would these blades be ok? SM
 



Droider

Droider

Drone Enthusiast
Ahh not sure they go that big.. check out the website I linked you to. Drop them a line they are usually back to you very quickley. There are some new 12" carbon ones out in Australia.. will find the link

Dave
 

R

RTRyder

Merlin of Multirotors
Droider said:
Ahh not sure they go that big.. check out the website I linked you to. Drop them a line they are usually back to you very quickley. There are some new 12" carbon ones out in Australia.. will find the link

Dave
Click to expand...

Aerobot has them, http://www.aerobot.com.au/shop/index.php?_a=viewProd&productId=92 or Quadrocopter in the US is stocking them as well http://shop.quadrocopter.us/Aerobot-12x38-Carbon-Fiber-Propeller-Pair_p_303.html. Be prepared to dig deep if you need 6 or 8 of them, about $50 US a pair...

As for Graupner, unfortunately they do not (yet) make what we need in a 12 inch size. I just put a set of APC 12 x 3.8 on the Droidworx Heavy lift and find they work much better than any of their smaller sizes, of course right now they're the only game in town so like 'em or not they'll be staying on the HL until something better comes along.

Ken
 
Last edited by a moderator:

Bartman

Bartman

Welcome to MultiRotorForums.com!!
I received my shipment of Xoar wood props a couple of days ago and I think they're going to be just about perfect. The blade is a little deeper in chord in the outboard half and just about the same as the Graupners in the inboard half. That little bit of extra bite in the outboard half should make them close to perfect as I thought the Graupners gave up a little too much lift when I first went to them. The Xoars are also noticeably stiffer in the tips than the Graupners.
Xoar makes a variety of sizes of the PJA and PJA-P props so I suspect there is a 12" version. I'm probably going to special order a batch of the 11"x5" props for my X650 if anyone is interested.
Bart
 

Bartman

Bartman

Welcome to MultiRotorForums.com!!
Xoar props arrived and they're mounted but I can't get outside between rain and wind. It sounds like RTRyder has his in place but suffered a mishap. Did you like the props Ken before the mishap?
I'm hoping to get outside tomorrow to finally test them out.
Bart
 

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