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Old Oct 24, 2010, 11:30 AM
Team Hacker
Geoff Dryer's Avatar
Vancouver BC Canada
Joined Jul 2006
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Originally Posted by eajohnson View Post
Hi guys,

I just maidened my 35% H9 Extra (electric) this afternoon. I was taking a year off flying for travel and fitness, but was back on a mission this fall to get this plane in the air!

Plettenberg Predator 30/8 on 14S/10Ah, Engel 28x14 prop (also have a Mejzlik 26x15 electric but I need shorter bolts to mount it), AUW 30lb 6oz. It pulls ~196A on the ground with full packs. I flew a short (5 min?) flight with the idea of seeing if the wings were going to fold on me or not (they didn't - I pulled +ive and -ive G but no snaps yet). Put 2800mAh back in on today's flight, which did include one long upline where I gratuitously used full throttle. Full throttle is never, ever necessary on this plane as currently set up. I need to prop down. I'm hoping the Mejzlik 26x15 might be more efficient, as power is well in excess of requirements and good flight duration is more of a concern.

Over the winter I'll get a custom motor mount built from aluminum and that should shave off enough I hope to get it under 30lb AUW.

Some guys were shooting video so hopefully will have a link sometime next week. In the meantime there is the ground test and motor runup from last week: http://www.bottomlinestudios.ca/Site...a_Testing.html
Congratulations on a successful maiden. At around 30 lbs and 196 Amps it must be ballistic!
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Old Oct 24, 2010, 12:38 PM
The Eh Team
Ottawa, Ontario, Canada
Joined Aug 2000
954 Posts
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Originally Posted by Geoff Dryer View Post
Congratulations on a successful maiden. At around 30 lbs and 196 Amps it must be ballistic!
Yep, and that's 196A on 14S too. There's so much more power than is needed I'm definitely going to try propping down; I'd like to try the Mejzlik 26x15, Biela 26x16, Biela 26x14, and Engel 27x14 to see how those go. BTW the motor came down barely warm to the touch and same with the batteries.

What prop did you eventually settle on for yours Geoff? (and what RPM are you spinning it at @ full power on the ground?)
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Old Oct 24, 2010, 02:01 PM
Team Hacker
Geoff Dryer's Avatar
Vancouver BC Canada
Joined Jul 2006
1,169 Posts
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Originally Posted by eajohnson View Post
Yep, and that's 196A on 14S too. There's so much more power than is needed I'm definitely going to try propping down; I'd like to try the Mejzlik 26x15, Biela 26x16, Biela 26x14, and Engel 27x14 to see how those go. BTW the motor came down barely warm to the touch and same with the batteries.

What prop did you eventually settle on for yours Geoff? (and what RPM are you spinning it at @ full power on the ground?)
I found the most efficient combination with the best power curve (for IMAC) to be the Hacker A100-8 with a Xoar 24x12 This is about 150A at full throttle. I don't recall testing the RPM with with combination. All last season I used the Hobby King Flightmax 30C 5800 mAh packs (12Sx2P)
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Old Oct 24, 2010, 04:40 PM
The Eh Team
Ottawa, Ontario, Canada
Joined Aug 2000
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Originally Posted by Geoff Dryer View Post
I found the most efficient combination with the best power curve (for IMAC) to be the Hacker A100-8 with a Xoar 24x12 This is about 150A at full throttle. I don't recall testing the RPM with with combination. All last season I used the Hobby King Flightmax 30C 5800 mAh packs (12Sx2P)
Sounds like I should be aiming for a prop that pulls around 125A at full throttle on 14S.
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Old Oct 24, 2010, 08:09 PM
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You guys all seem to have experience with the Mejzik 26x15E. I am running an APC 26x15E prop at around 100 amps on 15S, will the Mejzik give more power? figure it would be stiffer and all. Thanks
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Old Oct 24, 2010, 08:12 PM
Barefoot Birkinsomething
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United States, CA, Hayward
Joined Aug 2004
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Originally Posted by yellowbird2800 View Post
You guys all seem to have experience with the Mejzik 26x15E. I am running an APC 26x15E prop at around 100 amps on 15S, will the Mejzik give more power? figure it would be stiffer and all. Thanks
in general, the mejzlik's are stiffer than the apc's (your assumption is completely correct ), which means the apc props cavitate much easier and more often, which i believe makes it lose some efficiency.

basically, the mejzlik should make it feel like you have a lot more thrust. i love my mejzlik, and i think you would love it a well!
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Old Oct 24, 2010, 08:40 PM
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Thanks, I will order one tomorrow. Anybody recommend where to get it? Desert Aircraft sells them but I can't order on line, only by phone I guess?
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Old Oct 24, 2010, 08:47 PM
Barefoot Birkinsomething
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Originally Posted by yellowbird2800 View Post
Thanks, I will order one tomorrow. Anybody recommend where to get it? Desert Aircraft sells them but I can't order on line, only by phone I guess?
yeah, just give them a call. thats where i got my mejzlik, they are super nice on the phone and get the order processed pretty quick
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Old Oct 24, 2010, 09:15 PM
The Eh Team
Ottawa, Ontario, Canada
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Originally Posted by yellowbird2800 View Post
You guys all seem to have experience with the Mejzik 26x15E. I am running an APC 26x15E prop at around 100 amps on 15S, will the Mejzik give more power? figure it would be stiffer and all. Thanks
How big is the hub on the APC 26x15E? I would try one except APC didn't respond to my questions about the prop (max rpm and whether it was safe to drill) so I didn't chance it.
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Old Oct 24, 2010, 09:19 PM
The Eh Team
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Originally Posted by rcbirk21 View Post
yeah, just give them a call. thats where i got my mejzlik, they are super nice on the phone and get the order processed pretty quick
Desert was out of stock a couple weeks ago when I was looking to buy one so I bought one from Energon Solutions in the UK (energonsolutions.co.uk). It got to me quite a bit faster than shipments from the USA do (I'm in Canada). They shipped very promptly and the UK postal system is excellent and reasonably priced.
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Old Oct 24, 2010, 09:43 PM
aka Schleppmeister
PA
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Originally Posted by yellowbird2800 View Post
Thanks, I will order one tomorrow. Anybody recommend where to get it? Desert Aircraft sells them but I can't order on line, only by phone I guess?
if they are not in stock at DA:

http://www.aero-model.com/Mejzlik-26X15-Prop.aspx

http://www.e-flightline.com/props.htm

Thanks

http://iflytailies.jimdo.com/
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Old Oct 24, 2010, 10:36 PM
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Eajohnson, the APC hub is just over 1 5/8 inches wide and just over 1/2 thick.
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Old Oct 25, 2010, 09:06 AM
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Moss, Norway
Joined Jul 2003
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eajohnson,
APC have information regarding max. rpm on their website:
http://www.apcprop.com/v/html/rpm_limits.html

Thin electric props: Max rpm=145000/prop diameter (inches) so 145000/26=5575 rpm.
Your Predator 30/8 on 14s probably does about 6300 rpm on that propeller, so I would not risk it.

I have run the Mejzlik 26x15E and the Engel 28x14 on the 30/8. (on 15s, model weight 16.2 kg/35.5 lbs. But even at that weight, I reduced the max power to somewhat similar to 14s battteries. Plenty power)

Personally I prefer the Mejzlik, it seems to pull better, and is quieter in the air.

Regards,
Magne
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Old Oct 26, 2010, 10:35 AM
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I completely agree, 6300 rpm would be scary with an plastic E prop. My set up is way less rpm than that. Ordered the Mejzlik from Eflightline yesterday but will take a while to get since it is coming from WA to the east coast.
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Old Oct 26, 2010, 11:29 AM
Where is that remote?
lazyboyflyer's Avatar
Wildomar, California, United States
Joined Sep 2004
487 Posts
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Originally Posted by yellowbird2800 View Post
I completely agree, 6300 rpm would be scary with an plastic E prop. My set up is way less rpm than that. Ordered the Mejzlik from Eflightline yesterday but will take a while to get since it is coming from WA to the east coast.
That was a BIG mistake!! My son ordered the same prop from them online, got order confirmation and waited 2 weeks before he got an e-mail that they could not deliver the prop. Time wasted, cancell your order NOW!
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