Cutting props down in diameter

[Bartman]

Anyone have an opinion on cutting props down to smaller diameters? I'm without props for my Okto and it'll be three weeks if I wait for the 10x5 props but the 11x5 may be available next week. I can cut and balance the 11x5 but thought I might be overlooking something so I thought I'd ask. I kind of like the idea of an 11" prop cut to 10" since the blade/hub joint will be stronger and the blades a little stiffer.
Thanks,
Bart

 

[RTRyder]

First off, which props? Some I would cut, others not...

If you have room to swing the 11 inch props, just use them as is, the stock motors should be able to handle them. I'll be installing a set of 11 inch on the Hexa as soon as the sled dogs from Fedex make it across the snowbound city from their terminal facility.

Given the weather across most of the eastern US and upper midwest, I doubt the new F/C board I ordered will be arriving anytime soon so having the props right now isn't going to help me much

Ken

 

[Bartman]

Graupner E-props, 11x5
My MK Okto doesn't have room for 11" props. the props are off right now but as i recall, the tips were probably less than an inch apart.
Thanks,
Bart

 

[RTRyder]

OK then, I'll save you the effort. If you want I'll send you a set of 10 x 5 Graupners from my stock of spares as long as you replace them once they're back in stock. I'm waiting on the 11 x 5 to try out on the Droidworx Hexa which will take up to 12 inch props, I have a set of APC 11 x 4.7 that hopefully will arrive today so I have plenty of props on hand and there's so much &$#!#@ snow outside I can't do much flying anyway.

You'll still need the 8 to 5mm adaptors regardless of which way you go (or 8 to 6mm if you have the heavy lift motors)

Ken

 

[Bartman]

Thanks Ken!!!!
I've got 6 or 8 sets on order and I'm expecting them to arrive in two to three weeks (doh! Graupner!!) so I'll send you some new ones as soon as I get them. I'll ask Sandy from www.v-eastonline.com to send the spacers today if he can.
I'll PM my address.
Bart

 

[RTRyder]

The APC props arrived today, since the Hexa is down until the new F/C board arrives I put 4 on the Hoverfly quad to test them out. First thing I noticed, the blades are much bigger and shaped very differently than the Graupner props. Next thing I noticed, the tracking on these things is crap. Decided to put one on the balancer, ARRRRGGGGHHH... now I remember why I like the Graupners so much, I'll be lucky if can even get these pigs to balance, period.

I did spin up the motors on the Hoverfly and I will say the APCs push a lot more air than the Graupners and once they get some rpm they appear to start tracking better but so far all they've done is confirm to me that I really don't like APC for good reason. Graupners may be more $ but I'll gladly pay it to not have to spend a half hour trying to get one balanced or find that it doesn't track right after installation.

I'm hoping tomorrow the weather is decent enough to go outside with the quad and get it in the air with the bigger props, I'm very curious to see the difference though I doubt that I'll be using these long term.

Ken

 

[Bartman]

i think the Xoar's will be pretty sweet running props, fwiw. and the more i think about it, the more i like the idea of cutting 11's down to 10 to get a stiffer blade and better prop/hub joint. have any 11's you can cut and test?

 

[RTRyder]

i think the Xoar's will be pretty sweet running props, fwiw. and the more i think about it, the more i like the idea of cutting 11's down to 10 to get a stiffer blade and better prop/hub joint. have any 11's you can cut and test?

There isn't enough difference in the blade root between a 10 inch and 11 inch APC prop to make it worth the effort of cutting the 11 down. Within the same brand and type of prop there's also not that much of a difference in the blade itself from 10 to 11, the only time I would even consider the work necessary to cut the prop down then get it balanced correctly is to get a size that isn't available any other way. Cutting down APC props probably wouldn't be that difficult, just time consuming and tedious to get each one just right.

I wouldn't even consider cutting a Graupner, I don't know that the material they're made of lends itself to that sort of thing and they're so nicely balanced out of the package it would be a shame to mess it up.

I don't know that an EPP prop would survive being trimmed and I don't trust them in stock form, so definitely not a candidate for trimming unless its going on a beater.

Ken

 

[Bartman]

i defer to the gentleman from Boston.

 

[Bartman]

Ken,
The good news, the props arrived today, thanks again.
The bad news, the adapters i got two weeks ago are the wrong size!!!! Arggggghhhhhhh!!!!
I never bothered looking at them because I didn't have the props. Arggggghhhhhh!!!!!!
&$!**?*%^#!!@!*!!!!!!!
I feel better now.
Bart

 

[Droider]

Heheeeee. me Graupners arrived to day.. Got back earley from working away with a few packets of goodies on me desk.. interrogation by her indoors was worth the hassle!!..
If these fly as good as they look then their well worth the sheckles.. Even the packaging is quality! Germans.. they know how to make stuff pucker..

 

[Droider]

Prop Profile

So These Graupners.. do they genarate as muck lift as the APC's They look well skinny in comparison!?

 

[RTRyder]

So These Graupners.. do they genarate as muck lift as the APC's They look well skinny in comparison!?

They're a very different blade profile from those APC, look at how big the root of the blade is on the Graupner compared to the APC. They do not generate as quite much lift as the APC but they are much stiffer and quite a bit stronger, plus if you put each one on a prop balancer you'll find the Graupners are near perfect out of the box, the APC are generally rather far off. I've also had issues with the APC not sitting square and concentric on the prop adaptor and consequently not tracking true when spinning, overall too problematic to make them worth using when there's a better alternative that's a lot less work IMO.

Ken

 

[Droider]

Yep... I put a couple on the balancer last night and blade balance was almost perfect and hub balance was spot on.. I got a set of 10" and a set of 11" hopefully I will be trying them today.. weather permitting.. Ill report back

 

[Droider]

Ok just did my first hover with the 10" Graupners on and I am about 10% more throttle to get it up. Do you recon if I shove the 11" ones on they will be about the same lift as the 10" APC's? Also do you recon my motors will be ok with the 11" (AXi 2217/20's)