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Old Feb 12, 2012, 01:35 AM
Livin it UP when Im goin DOWN
Arcteryxxx's Avatar
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Wow! Thanks for sharing those very interesting numbers, Peter!
Do you have any guesstimate of the actual speed you got out of the surprisingly high pitch speed/watt ratio?
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Old Feb 12, 2012, 01:58 AM
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Quote:
Originally Posted by jackosmeister View Post
The big question is, was it fast?
Not fast in drag racing from one side of the field to the other, but hugely fast if you fly one complete and continuous circuit at WOT to allow it to get "on step"!

I need to fly both props more to figure out what I like best, but both are good.

Also whilst the current level for the 23 looks low, the motor temperature indicates that you wouldn't be safe running WOT continuously.
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Old Feb 12, 2012, 02:35 AM
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Quote:
Originally Posted by Arcteryxxx View Post
....Do you have any guesstimate of the actual speed you got out of the surprisingly high pitch speed/watt ratio?
I think I'm going to have to do some dopplers to get the facts.
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Old Feb 12, 2012, 02:37 AM
Livin it UP when Im goin DOWN
Arcteryxxx's Avatar
Norway, Telemark, Skien
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Quote:
Originally Posted by Peter M View Post
I think I'm going to have to do some dopplers to get the facts.
I concur
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Old Feb 12, 2012, 04:56 AM
Crashing into the sky!
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Auckland NZ
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Heres the numbers off my oversqaure prop testing, not a direct comparison, but hey

This was the fastest pass, which happened to be the pass before I landed. Its hard to judge the speed acurately, but its fast Wouldnt be surprised if its 170mph+

Vertical power on climb, roll over the top and power on back down. The way I figure it, is that its unloading in the usual way, not a big rpm gain, but watts and amps drop off as it accelerates.

16/25/2 KPG25 5.2 6S 1600 45C RFM 14.5x14 prop, .4" hacked off each blade on a 42mm +5 degree aeronaut centre. Measures up as 14x21" prop
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Old Feb 21, 2012, 08:07 PM
Carbon fiber is our friend
Steve C's Avatar
United States, CA, Lodi
Joined Feb 2001
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Quote:
Originally Posted by Peter M View Post
I think I'm going to have to do some dopplers to get the facts.
I flew a geared motor right over the top of a camera and you can't make out a clear doppler curve. There's too many sounds coming out I guess

We tested a new prop on a Cyclone last weekend. It took a bit of time to un stall, but once it did it was very fast. The pinion came loose, so I ordered some 648 and I'll get it back in the air with a radar gun and maybe Eagle Tree to see how many amps it pulls in the air. Motor is Mega 1635/1 Kontronik 4.2 and 4S lipo. I think it will be okay on 5s once the pinion is secure, but I wish those things had set screws like the old Aveox box.

Steve C
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Old Feb 22, 2012, 02:14 AM
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Steve,
Nice work on your props! (More info here: http://www.rcgroups.com/forums/showthread.php?t=1595613)

Are you running a ICE controller that could give some inflight data or do you have to stuff your Eagletree in there first to get some numbers?

I'm planning on installing my Mega 16/35/1 with 5.2:1 gearbox into my Plasma in the next week or two to get some data with my Koch blades. I'm interested is seeing the effect of going from my 3100kV Kira to the 3500kV of the Mega.

Please continue to post your thoughts and any data you harvest as there is a few of us very interested!

Regards
Peter
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Old Feb 22, 2012, 04:24 PM
Carbon fiber is our friend
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Thanks Peter.

No ICE in this one. Are they more reliable than the Phoenix line? I can still smell Phoenix guts in the Cyclone

I have an Eagle Tree here, so I'll get that installed for the next flight. I want to know too! I think we'll find that the amp draw on 4s is reasonably low. The battery and controller were pretty cool to the touch after the first flight.

I'll let you know when I have some data to share.
Steve
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Old Feb 23, 2012, 02:14 AM
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Thanks Steve!
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Old Feb 24, 2012, 12:48 AM
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Some interesting comments from Yello regarding F5D folder design: http://www.rcgroups.com/forums/showp...0&postcount=21
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Old Feb 26, 2012, 03:03 AM
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Dr Marcus Koch - 9.8 x 17.5 Blades on Mega 16/35/1 5.2:1

This afternoon I got to very briefly run my new Koch 9.8 x 17.5 on an RFM spinner, Mega 16/35/1 5.2:1 and Turnigy 5 cell 1800mAh 30-40C battery in my Plasma II and was pleasantly surprised at the nice mix of acceleration and speed.

Inflight reasonably level and ALMOST unloaded gave:
17.4 volts or 3.48 volts per cell at 24% discharge
65 amps
1132 watts
11,340 rpm or a pitch speed of approximately 188 mph

Looking at the graph indicates I need to run it longer to allow it to completely unload.

Like when it was on the Kira, it was a great balance of acceleration and speed and great fun but boy, was the motor hot on landing!
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Old Feb 28, 2012, 03:03 PM
never mind the boll⁣⁣⁣ocks
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Australia, NSW
Joined Dec 2010
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careful peter.... much longer and she might be toast!
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Old Feb 28, 2012, 03:09 PM
Crashing into the sky!
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Its strange that its hot, 65A is naff all for a 16/35/1
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Old Mar 02, 2012, 04:03 PM
Livin it UP when Im goin DOWN
Arcteryxxx's Avatar
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So, what airspeed can be expected from a F5D ship with a 8x23 rotating at 12500 rpm?
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Old Mar 02, 2012, 07:49 PM
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Arctery,
I think the answer is ultimately zero, zilch, zippo........................................and pieces of airframe spread over a large area!

I think you're in the realm of Speedcup models now and the common F5D airframes won't hack 272mph pitch speeds from 8 inch blades for long. I also think that sustaining that level of power will require larger capacity batteries than will fit in a F5D fuselage.

I think you'll be spending more time on German language websites but please post whatever you come up with!

Ambrose and Jacko,
I am surprised how hot the 16/35 runs too. I guess I need to compare the temps with what Heliclown is seeing with his similar setup to see if I have a motor problem.
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