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Old Oct 09, 2012, 05:54 AM
"The Judge"
sebbe's Avatar
Sweden
Joined Feb 2006
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Originally Posted by DownUnderPilot View Post
@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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Old Oct 09, 2012, 11:12 AM
Why the dirt on the wings?
moparmyway's Avatar
New York
Joined Jan 2009
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Originally Posted by DownUnderPilot View Post
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 !
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Old Oct 09, 2012, 05:11 PM
Registered User
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United States, CA, SF
Joined Mar 2008
3,812 Posts
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
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Old Oct 09, 2012, 05:20 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
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@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!!!!
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Old Oct 09, 2012, 05:42 PM
Registered User
GryphonRCU's Avatar
United States, CA, SF
Joined Mar 2008
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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
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Old Oct 10, 2012, 02:18 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Lšn, Ljungby
Joined Jan 2001
4,762 Posts
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Originally Posted by DownUnderPilot View Post
@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.
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Old Oct 10, 2012, 02:27 AM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
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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?
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Old Oct 10, 2012, 06:12 AM
Why the dirt on the wings?
moparmyway's Avatar
New York
Joined Jan 2009
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Quote:
Originally Posted by DownUnderPilot View Post
@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
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Old Oct 10, 2012, 07:19 AM
"The Judge"
sebbe's Avatar
Sweden
Joined Feb 2006
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Originally Posted by moparmyway View Post
I am gunna hit those babies with 12 cells and some BIG motors ............
I will post up the ICE graph after testing is done
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Old Oct 10, 2012, 02:34 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
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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....
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Old Oct 10, 2012, 03:22 PM
Drinks Day Old Expired Milk
VooDoo Child's Avatar
United States, OR, Portland
Joined Aug 2010
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Originally Posted by DownUnderPilot View Post
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
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Old Oct 10, 2012, 04:09 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
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I'd also like to reveal that the prop I'm making actually is ~4.7x6.1

I added +2.5 degrees pitch...
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Old Oct 10, 2012, 07:13 PM
Chillaxin dude!
BulletMaster's Avatar
Newcastle, NSW, Australia
Joined Apr 2003
4,783 Posts
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Originally Posted by DownUnderPilot View Post
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...
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Old Oct 10, 2012, 08:09 PM
Crashing into the sky!
jackosmeister's Avatar
Auckland NZ
Joined Aug 2007
7,145 Posts
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/
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Old Oct 10, 2012, 09:30 PM
I am actually really slow
SlowBarless's Avatar
Brisbane
Joined Jun 2008
947 Posts
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.
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