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Electric setup for herr rubber powered cub

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Old 08-10-2013, 03:50 PM
  #1
Steve Westphal
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Default Electric setup for herr rubber powered cub

We are building a 30" Herr rubber powered Piper Cub and want to power it with electric. Any suggestions as to the correct motor and esc for this project? I would like a motor that will power planes a bit bigger also. Just getting into electric, but, we are still flying glow and will continue as we love it. Please let me know the gear such as brand and size. Has anybody flown one of these Cubs with electric? It seems as though it should be a good flyer with electric. Any suggestion will be greatly appreciated.
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Old 08-18-2013, 09:50 PM
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I went into the stockroom and tonight had a quick look at the Herr Cubbie Kit. Forgot how well designed this line of smaller airplanes are.
I have used the small 180- 250 range from Heads up R/c
Check these out..

http://www.headsuphobby.com/HURC-180...otor-H-560.htm

http://www.headsuphobby.com/Power-Up...otor-F-545.htm

You shouldn't need 3 cells...
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Old 08-19-2013, 05:51 AM
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Last year I completed a Herr Engineering - Star Lite and modified it with ailerons (see picture below), I posted a thread about the build here on RCU - Herr Engineering - Star Lite . The wing span is 24 inches so its close in size to your cub.

For the power plant I used the "Grayson Hobby - Indoor Combo - 2204 & 10Amp ESC - Link http://www.graysonhobby.com/catalog/...esc-p-510.html, I used a 2S 800 Mha battery and it pulls the plane quite well. It REALLY pulls the plane with a 3S battery, but I think it overheats the ESC because of air flow. I've got SEVERAL of the Grayson Hobby's Combo's with the "Welgard" brushless motors and they ALL work GREAT for the money. If you think you'll need more power, I usually go by 200Watts per Lb., then you might want to opt for the next combo up, the 370 Brushless Outrunner Motor & ESC (GH2208 Series) Link http://www.graysonhobby.com/catalog/...ies-p-334.html

Good luck in your build,and have FUN!

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Old 08-19-2013, 05:57 AM
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Hey, I just went on the "Herr Engineering" site and they recommend a 280 class brushless motor for the Cub kit. Just thought I'd let you know.
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Old 08-19-2013, 07:12 AM
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At these smaller sizes a few grams can make all the difference in how the model flies. If your goal is to keep the rubber powered like slow flying speeds I'd suggest you stay with one of the micro motors. This will also allow you to use a smaller pack for even more weight saving. With this in mind I'd suggest that a 280 class brushless is still too big a motor when there are other 13 to 15 gram micro motors that can still punch out the approximately 30 watts of power that would work very nicely with a 5'ish oz model.

For example here's a motor that says it'll handle up to 60 watts.
http://hobbyking.com/hobbyking/store...00kv_14g_.html
Even if that is the burst power it should easily handle the 30'ish watts needed for a light Cub. And it's only 11 gms. Couple this with a small 15AESC and something like a 2 cell 300 to 400 mah pack and you've got a nice light setup for flying smaller and lightly built stick and tissue models such as the Herr Cub.

Most certainly a 30 inch span Cub model will still fly even at a weight of up around 10 to 12 oz. But it won't look like a Cub while doing so. To keep the light and airy look of a proper Cub, especially one derived from a rubber power kit, you want to keep the weight down to around 4 to 5 oz. But you won't get that if you insist on a motor and pack that'll do well in a bigger model.

As a side benefit the lighter target of a sub-5oz weight will tend to make the model tougher during less than ideal landings where a heavier model will tend to act like an internal hammer unless even more weight is added with reinforcing the airfraime. This whole thing can easily spiral out of control until you end up with what has sometimes been described as a "weak rock".

It's your choice

Last edited by BMatthews; 08-19-2013 at 03:13 PM. Reason: Forgot link and spelling mistakes
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Old 08-19-2013, 07:25 AM
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Are you dong the Cubbie on Floats? Herr has three flavours of Cub
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Old 08-19-2013, 08:01 AM
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OK, looks like I misunderstood WHICH Cub you were building. Sorry about that, I assumed it was the "Electric" Cub, and NOT the Rubber powered cub, even though you said "We are building a 30" Herr rubber powered Piper Cub". With that said, I would have to AGREE with a motor size of 180-250 size motor. I actually built a Guillows "Lancer" and used a Great Planes - 180 Rimfire motor. Its plenty of power and a BLAST to fly. Sort of like a "micro" glider.

Here's details of my build "by Guitardude" http://www.wattflyer.com/forums/show...t=67133&page=2
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