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Old Sep 14, 2014, 06:07 AM
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tomooska's Avatar
Joined Jan 2007
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Quote:
Originally Posted by blitzu View Post
Nice machine wrk Tom!!
Now I know who to contact when I need a +5š,3blade hub (42mm hub thou,cause running 22 serries mtr)
At first I thought you said a 2 blade which would be easy, 3 blade is still doable but will take a bit more work. Remind me soon and I'll see what I can do. Is this for the 3x 5.25x7 blades you got from dean is it? Have you tested them on a standard 3 blades yoke yet?


Quote:
Originally Posted by moparmyway View Post
90 amps down to about 50 on an oversquare prop is nothing but magic !!

My hat is off to Dean - what an accomplishment !!

No 28mm motor operating @ 2600 watts is ever going to have an easy time unloading, but Deans props keep their shape, are uber light, and are thin .......... a recipe for speed and an unbelieveably efficient setup !!!

Thats one nice stand you built there !!!!

3 blade needs double oversquare !!
It's a similar percentage drop to what you have said but the static amps were ~100 and they unloaded to 60 amps, sometimes a little more. If you look on the graphs, there is a key to tell you what line is for amps and watts.

----------

Will be flight testing 7s soon with the old 6.25x11 blades on a 30mm yoke (so they will be smaller)... Static on that gave me 98A and 28500rpm
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Old Sep 14, 2014, 06:47 AM
Why the dirt on the wings?
moparmyway's Avatar
New York
Joined Jan 2009
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Quote:
Originally Posted by tomooska View Post
old 6.25x11 blades on a 30mm yoke ... Static on that gave me 98A and 28500rpm
........ and I believe the 6.25x11's will have the Formula - Swist - X - Rifle.......... and even the FJU crowd gathering around !!!!

I am VERY eager to see this inflight data !!
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Old Sep 14, 2014, 02:38 PM
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blitzu's Avatar
New Zealand, Bay Of Plenty, Omokoroa
Joined Dec 2012
791 Posts
Quote:
Originally Posted by tomooska View Post
Remind me soon and I'll see what I can do. Is this for the 3x 5.25x7 blades you got from dean is it? Have you tested them on a standard 3 blades yoke yet?
Hi Tom-yip its for the 5.25x7's from Deano.
I have done any testing yet...I've got a few more bills to pay first.
Then approx 7hundys worth of x3 esc's to save for...
Hopefully by then the LHS has reopened,(they're been shifting premises)and are the only agents in N.Z that can order my Horeson batts...

So a wee while away...but when all arrives I'll have x2 planes going and be able to do some decent testing,see where things are at and take it frm there.

Your offers much appreciated as its quite a technical job (I'll fix you up some $ for it)

Will definitely be in contact thou-CHEERS!
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Old Sep 17, 2014, 02:19 AM
300 mph club ;-)
M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
523 Posts
New 7x12, 7x13, 7x14, 8x12, 8x13, 8x14 Powercroco-folders

Hi Speed-guys!
Good news on the new props!
Gerd (Amperegerd) tested the new 7x12 on the monster yesterday and got very, very good results in comparison to the old 7x13 folders!
Here are the first data:

Motor is a Strecker serial motor without tuning
7x12 Powercroco new in flight data (yoke is a 34 mm which results in a 6,8x12)
Rpm: between 28-29.000
A: 95-80A
speed: 410-420 km/h
W: 3900W going down to 3300 W in flight

7x13 Powercroco old in flight data
Rpm: around 28.000
A: 165-140A
speed: 400-420 km/h
W: 5800W going down to 4700W in flight

Seems to work really good in comparison to the old one. Today he is testing the 7x13 new and 7x14 new on the monster.
The molds for the new 8x12, 8x13 and 8x14 Powercroco props are also ready and the first blades are ready for testing!
The new 7x10, 7x11, 7x15, 7x16, 8x15, 8x16 and 8x17 will follow soon!
Due to the new root the props fold very well on small yokes so you can hide nearly all the yoke under the spinner cap!
And the new props are much more quiet in comparison to the old one in flight!

Ciao, Marcus
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Last edited by M. Koch; Sep 17, 2014 at 02:25 AM.
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Old Sep 17, 2014, 02:33 AM
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blitzu's Avatar
New Zealand, Bay Of Plenty, Omokoroa
Joined Dec 2012
791 Posts
Awesome Marcus! Thats a major amp drop
Put my name down for two pairs of 7x12's please
Will pm you...cheers
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Old Sep 17, 2014, 03:05 AM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
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Well done Marcus! My experience shows we can build really quite thin carbon blades, they are strong enough, and draw so much less power. This has the obvious benefit of allowing a lighter power system. Which leads to faster airframes ultimately!
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Old Sep 17, 2014, 03:26 AM
300 mph club ;-)
M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
523 Posts
Hi DUP!
Thin is good, too thin results in an odd sound !
Niklas Kahlich tested a new designed 11x20 folder at the world record attempts in Ballenstedt with a very thin profile on the prop which resulted in a very nice but also very flexible prop. The sound was really strange in flight due to i think vibrations in the blade at our power levels. Would be a great prop for F5D or up to 2,5 KW but i think above 3KW it is to thin and flexible!

Ciao, Marcus
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Old Sep 17, 2014, 01:58 PM
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Calgary, AB, Canada
Joined Oct 2002
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Quote:
Originally Posted by M. Koch View Post
Here are the first pictures for the molds , Marcus
You guys are doing some real innovative work!

I'm intrigued by one particular feature of the molds. I'm not sure if its an optical thing with the photo's, but it almost seems like the LE & TE periphery of both mold halves are extruded positive shape "U" but in opposing contact ...vs. matched top/bot "U" index that would nestle within each like a typical mold dimple shape. Hope this question makes sense. If so, is that to pinch a sharp LE & TE contact line?
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Old Sep 17, 2014, 03:22 PM
300 mph club ;-)
M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
523 Posts
Hi Ptxman!
The molds are designed that there is only a small pinch point around the LE and TE of about 2-3 mm which has an distance of about 0,10 mm to allow dispensable resin to get out of the mold! After these 2-3mm there is an offset of 1mm in the top and bottom mold to allow the dispensable resin to stay there. The two mold halves only have contact on the 4 edges which allows to close the molds completely without resin blocking the complete closure.
Even 0.1 mm resin between the parting lines means about a 7% wrong profile in a 1,5 mm thick prop blade! The special design of the molds prevents this effect! Why doing a lot calculations on the computer, cnc-milling exact molds, when you destroy everything by laminating the blades!

Ciao, Marcus
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Old Sep 18, 2014, 08:15 PM
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arcticflyer's Avatar
Canada, SK, Prince Albert
Joined Jan 2006
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Marcus - just got my 11x20S set...THANKS! Forgot to ask you, what is the KW limit on these?
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Old Sep 18, 2014, 08:47 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
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Probably more than you can throw at it!

An RPM limit might be more appropriate ?
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Old Sep 18, 2014, 09:29 PM
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Canada, SK, Prince Albert
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With what I got right now you're right! Just curious!

Plan on throwing some KW's at it tomorrow or Saturday and getting some passes for Doppler.
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Old Sep 18, 2014, 09:32 PM
2012 NZ Speedcup - 231 MPH
DownUnderPilot's Avatar
New Zealand, Tasman, Richmond
Joined Mar 2006
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Quote:
Originally Posted by arcticflyer View Post
With what I got right now you're right! Just curious!

Plan on throwing some KW's at it tomorrow or Saturday and getting some passes for Doppler.
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Old Sep 19, 2014, 01:37 AM
300 mph club ;-)
M. Koch's Avatar
Regensburg, Germany
Joined Apr 2003
523 Posts
Hi articflyer!
The layup has been tested up to 30000 rpm and 10 KW are also no problem! Some of the props have been used up to 12KW peak, so donīt be afraid !

Ciao, Marcus
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