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Electric Conversion Question

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Old 12-06-2008, 12:00 AM
  #1
UkerDuker
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Default Electric Conversion Question

Where are the electric Guru's??? I need some assistance.

I have a scale project in the works that I originally planned to install 4 RCV90SP 4-strokes. I also planned to swing 15x12 4-bladed props. My prop cannot exceed 15" in diamter. The plane could have a flying weight of 40-50lbs.

I have decided to make the leap into converting this. Now my problem. I have been reading through these threads on electric motors, ESCs, glow to electric conversions and nothing seems to click. I have seen many comment about there being no conformity to the indentification of motors that would be a one for one swap.

My LHS has recommended the Neodym Neo60 motor. It requires an 80A+ ESC. Is this a decent motor? When paired up with a suitable prop, would this be a enough to to produce 10-15lbs of thrust? If not, what is a good alternative motor? The motor should not exceed 55mm in diameter to maintain a scale appearance. http://www.neodymmotors.com/neo060.php

How are the Castle Creations High Voltage ESCs? Would these be a good match for the above motor?

What size Lipos would be a good power source for these motors? How many cells?

As you can tell I don't know much about electrics. I am slowly learning the basics. I do not have any issues with experimenting and changing if I need a better product. I have found a few programs that allow for every possible number to be entered and changed, but these are difficult to work with when my knowledge is lacking. All comments and suggestions are appreciated.

Mike

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Old 12-06-2008, 06:21 AM
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Default RE: Electric Conversion Question

hi you cold use the E-flite 60 bl, 400kv . These generate up to 1200 watts each, giving you around 48 lbs of power on 7`s li-po. Use 80 amp esc`s. Overall diameter is 50mm.
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Old 12-06-2008, 11:25 PM
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Default RE: Electric Conversion Question

I have two KMS 5331-10 (250 Kv) motors, CC HV-45's and 8800mAh 12S4P battery. These are cheap motors, Axi's 5330/18 would do better, but I'm getting 24lbs peak thrust with 16x10 3-Blade props. If you double this, that would give you 48lbs thrust from a system that weighs 17lbs.
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Old 12-07-2008, 08:10 PM
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Default RE: Electric Conversion Question

Mike, what model bird are you building? I am on a Don Smith B-24 148" wingspan project and have the same question you have on electric motors. Gene
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Old 12-07-2008, 08:28 PM
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Default RE: Electric Conversion Question

gborn

I'm building a Palmer plans 1/12th scale C-130. I am making all the mods to make it an AC-130U. I believe I have the right motors and I plan to pair them with the Castle Creations 85A High Voltage ESCs. I guess I have final two issues:

- What prop (14x?) or (15x?) ?
- What battery?

Once I determine these items, I will setup everything and see what kind performance I get. This is a difficult challnge, but I will understand in time.
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Old 02-15-2009, 04:37 PM
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Default RE: Electric Conversion Question


You'll need to determine how fast you want (or need) the aircraft to fly. I believe it's 2-3 times the stall speed. Once you know the approximate speed then calculate the rpm x prop pitch to get that speed. Go for the biggest prop that your motor/ESC/batteries can handle without going over max amps. RPM = motor Kv x volts, figure 10 volts for a 3 cell lipo pack.

Bigger prop = more amps needed
Higher pitch = more amps needed
higher prop speed = more volts needed

When I was trying to figure out what to use in a four engine conversion I looked at the props I wanted to use versus how much room for batteries I had in the aircraft. I also wanted 8 min of flight so I figured in how many amps I could pull from the batteries I could carry. I determined I could fit 4000mah 3s lipos in each nacelle, I then selected a prop that gave me the speed I needed (60 mph) and the amp draw I wanted. I cheated a bit too, I used the Hobby-lobby prop charts with the AXI motors they sell to determine what motor/prop combo to use. They also list what size aircraft that motor could fly. My aircraft was going to weigh 18-20 lbs so I selected the AXI 2820-12 since it was listed as being a good motor for 5lb aircraft and turned a 10" prop, I used 4 of them. It had a max amps of 35 which was over what I needed and turned a 10/8 prop at around 25 -30 amps. It turned out to be pretty accurate. The motor/prop combo works perfectly for me.

One more thing - watts per pound- My airplane flies great at around 50-60 watts/pound.

Good luck!
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