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Oct 09, 2012, 06:54 AM
"The Judge"
sebbe's Avatar
Quote:
Originally Posted by DownUnderPilot
@Mopar, You are definitely getting a set of the 4.7x5.5's to test, don't worry, no-one is getting those until I can validate how much they can be revved to.
That is a very good idea before we other get them...
IF they just hold up to high rpm:s, then we can test them in planes and compare to apc 4.7x5.5...
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Oct 09, 2012, 12:12 PM
Why the dirt on the wings?
moparmyway's Avatar
Quote:
Originally Posted by DownUnderPilot
How can I forget you Sebbe!

You are next in line..... poor Mopar, it's looking like the 6x10's are going to be tested by planes!

I'm pretty confident they'll work quite well, though

@Mopar, You are definitely getting a set of the 4.7x5.5's to test, don't worry, no-one is getting those until I can validate how much they can be revved to.
DUP,
No worries here ......... I will test whatever makes its way over to my parts !
Oct 09, 2012, 06:11 PM
Registered User
GryphonRCU's Avatar
DownUnderPilot,

How close are you planning to get to 3-4KW testing if the 4.7X5.5 prop holds up as you increase cells and RPM?

Any predetermined limit or you will pour on the power till it blows?



I assume you will not bother trying to reach supersonic prop tip speeds since it'll be inefficient.

Gryphon
Oct 09, 2012, 06:20 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
@Gryphon - that's up to Mopar I guess, I am confdent they'll perform better than the APC version, because they are much stiffer, but I think there is not much sense in pushing them above 50K, assuming they survive at that speed.

It remains to be seen what the current draw is at that speed....

That's 275 MPh pitch speed!!!!
Oct 09, 2012, 06:42 PM
Registered User
GryphonRCU's Avatar
Ah, I get it now.

I thought you were doing some pre-validation before sending it to Mopar.

_________________

Mopar, have some ear plugs handy.



Gryphon
Oct 10, 2012, 03:18 AM
310mph Kolibri T25 Swist
henke's Avatar
Quote:
Originally Posted by DownUnderPilot
@Gryphon - that's up to Mopar I guess, I am confdent they'll perform better than the APC version, because they are much stiffer, but I think there is not much sense in pushing them above 50K, assuming they survive at that speed.

It remains to be seen what the current draw is at that speed....

That's 275 MPh pitch speed!!!!
From my calculations you will need about 6kW input power to reach 280mph with a Swist in level flight.
Oct 10, 2012, 03:27 AM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
So safe to assume 50K RPM is going to be a lot less power than that! If you got 80% of pitch speed (maybe) then 220 MPH top speed. Possible?
Oct 10, 2012, 07:12 AM
Why the dirt on the wings?
moparmyway's Avatar
Quote:
Originally Posted by DownUnderPilot
@Gryphon - that's up to Mopar I guess, I am confdent they'll perform better than the APC version, because they are much stiffer, but I think there is not much sense in pushing them above 50K, assuming they survive at that speed.

It remains to be seen what the current draw is at that speed....

That's 275 MPh pitch speed!!!!
I am gunna hit those babies with 12 cells and some BIG motors ............
I will post up the ICE graph after testing is done
Oct 10, 2012, 08:19 AM
"The Judge"
sebbe's Avatar
Quote:
Originally Posted by moparmyway
I am gunna hit those babies with 12 cells and some BIG motors ............
I will post up the ICE graph after testing is done
Oct 10, 2012, 03:34 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
Mmmmm Ben (Slowbarless) pointed out to me that at 50K, we are looking at ~100kg of force on the blades. I'm not certain they'll take that much force. The root has 8x12K rovings in there, but even so.... I'm also sceptical the centre piece can take that sort of abuse.

Oh well, in the interest of science....
Oct 10, 2012, 04:22 PM
Drinks Day Old Expired Milk
VooDoo Child's Avatar
Quote:
Originally Posted by DownUnderPilot
Mmmmm Ben (Slowbarless) pointed out to me that at 50K, we are looking at ~100kg of force on the blades. I'm not certain they'll take that much force. The root has 8x12K rovings in there, but even so.... I'm also sceptical the centre piece can take that sort of abuse.

Oh well, in the interest of science....
My 16-35-1.5 on 6S w/APC 4.2X5.5 took 46 rpm.....just had to look at them after landing to make sure there were no stress marks around the hub....I realized that after I had one blow apart on me
Last edited by VooDoo Child; Oct 10, 2012 at 11:43 PM.
Oct 10, 2012, 05:09 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
I'd also like to reveal that the prop I'm making actually is ~4.7x6.1

I added +2.5 degrees pitch...
Oct 10, 2012, 08:13 PM
Chillaxin dude!
BulletMaster's Avatar
Quote:
Originally Posted by DownUnderPilot
I'd also like to reveal that the prop I'm making actually is ~4.7x6.1

I added +2.5 degrees pitch...
Now that's a prop I would like to try on the ElNino...
Oct 10, 2012, 09:09 PM
DroneWorlds - TEAM NEW ZEALAND
jackosmeister's Avatar
There is literally no point even going above mach .9 helical tipspeed (not just rotational tip speed, the planes moving forwards too).

Depends on the aiframe, but thats somewhere around 190mph and 48k rpm with a 4.7" prop.

All ya get is noise, and slower speeds (been there, done that)

Good article on spinning props too fast here http://www.supercoolprops.com/articles/
Oct 10, 2012, 10:30 PM
SB7
SB7
I am actually really slow
I wonder how many people know to watch for stress marks on APC props, they form quickly if you're running over 1kw on the s400 sizes usually less then 10 flights. As soon as they form the prop is toast and you should replace it. Carbon ones don't suffer from fatigue so quickly.

I think if you could get the blades to 40k that would be fine. Any further then that can be a 'use at your own risk' kinda thing.