Electric setup for 108" C-130
10-24-2013, 05:10 PM
#1
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Electric setup for 108" C-130
I want to use 4 electrics on a 108" C-130 rather than gas simply for the reliability. That being said i dont know squat about electrics. I am going to estimate that the model will wigh between 15-20 lbs, 20 lbs max as a high estimate. I have 2 2650 mah sky lipo batteries, I would like to use them if i can get the kind of power and flight time out of them that i will need. I was looking at using a 25 size outrunner as recomended by a friend but am unsure that this battery will cut it. http://www.rchotdeals.com/products/O...-lb-plane.html I have the option to use 730 840 or 1000 KV and a 50 or 60amp speed controler combo. Looking for input on this setup or other alternatives. I would like to know what kind of flight time i might expect from this setup flying at 60-70% power, and wheather or not i can run two motors off of one battery in order to save money, weight, and space. I also need a to know what prop to use, i would like to use a 3 or 4 blade prop, 11.5" with squared tips. I would likely buy a 13" prop and cut it down in order to square them.
10-27-2013, 07:44 PM
#3
That airplane is not a trivial project. I recommend doing a little more research on your power system - I don't think those two batteries are going to cut it for an airplane that big (maybe 4 of them per flight - one per motor - but I would have to put a lot of thought into how I would want to setup a 20lb, 108" 4-engine airplane). Batteries and power systems are not the place to skimp on a project of this magnitude.
The 2650mah is pretty low for an airplane of that size, you will be very limited in flight time unless you used 4 of them. My first inclination is something like a pair of 5S or 6S packs, 5000mah capacity.
The 2650mah is pretty low for an airplane of that size, you will be very limited in flight time unless you used 4 of them. My first inclination is something like a pair of 5S or 6S packs, 5000mah capacity.
10-29-2013, 04:12 PM
#4
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I didnt really figure they would be enough but was hopeful, maybe if i used 4. I have not settled on a power system yet and was just hopeful that i could buy 2 more batteries rather than 4. If you have any recomendations i would love to know what you would recomend for motors. i think i will be closer to 15lbs than 20, time will tell.
10-31-2013, 03:05 PM
#5
I have not done a 4-engine plane, but if I was about to start this is my thought process (actually I've been thinking lately about building a big scale DC-3 so this has sort of been in the back of my mind for the past few weeks).
First off, if you have some kind of failure you do not want both motors on one side of the plane to quit. So make sure you have both inboard motors powered off the same batteries, and both outboard motors powered off the other batteries.
My go-to motors are usually Hacker and E-flite. Both are very high quality motors with good product support. E-flite is a little less expensive, Hacker is a little higher performance with a little better technical assistance (as in calling from the flight line and getting someone on the phone who really knows these motors). Both of these motor brands can be run at their upper limits all day, every day, so there is no fear of pushing them and there is comfort in knowing you don't have to think much about something failing.
With 4 motors, I would probably divide overall weight by 4 and choose a motor for that size plane, i.e. choose motors for roughly a 4.5-5lb plane. This would bring you somewhere around an E-flite Power 25 or the Power 32. The Hacker A30 series is equivalent, just match the weight and kV. For me I'd think 3300mah would be a bare minimum, if not for anything else than the safety of longer flight time during the first few flights. I would weigh out the cost, desired flight time, and weight of battery packs (3S 3300 vs 3S 4000 vs 4S 3300, etc). I would decide on what power system I wanted, build the plane, then buy the batteries. This way you can get the biggest batteries you can afford (weight wise) for longer flight times and also not be stuck with bricks that are too heavy for your plane or that mess up the balance. I think my choice would be 3S packs and the Power 25 motors. It would cost less, likely weigh less, and be enough power. Higher mah packs will give longer flight times and run cooler, and cooler running packs last longer.
Here is a decent read to get started - it's geared toward electric twins, but same principle just double:
http://www.modelairplanenews.com/blo...win-electrics/
Here is an E-flite twin engine electric plane that is a little more than half the weight of what you're looking at. I would read the manual and basically copy the power system, X2 (meaning copy the way things are hooked up; copy the power system X2 if you decide on the Power 25 or 32, etc). You would get better performance though due to the weight, so the Power 25 would likely be fine. The manual should show you how to rig up your power system. Again, just double the wiring setup.
http://www.e-fliterc.com/Products/De...ProdID=EFL4550
First off, if you have some kind of failure you do not want both motors on one side of the plane to quit. So make sure you have both inboard motors powered off the same batteries, and both outboard motors powered off the other batteries.
My go-to motors are usually Hacker and E-flite. Both are very high quality motors with good product support. E-flite is a little less expensive, Hacker is a little higher performance with a little better technical assistance (as in calling from the flight line and getting someone on the phone who really knows these motors). Both of these motor brands can be run at their upper limits all day, every day, so there is no fear of pushing them and there is comfort in knowing you don't have to think much about something failing.
With 4 motors, I would probably divide overall weight by 4 and choose a motor for that size plane, i.e. choose motors for roughly a 4.5-5lb plane. This would bring you somewhere around an E-flite Power 25 or the Power 32. The Hacker A30 series is equivalent, just match the weight and kV. For me I'd think 3300mah would be a bare minimum, if not for anything else than the safety of longer flight time during the first few flights. I would weigh out the cost, desired flight time, and weight of battery packs (3S 3300 vs 3S 4000 vs 4S 3300, etc). I would decide on what power system I wanted, build the plane, then buy the batteries. This way you can get the biggest batteries you can afford (weight wise) for longer flight times and also not be stuck with bricks that are too heavy for your plane or that mess up the balance. I think my choice would be 3S packs and the Power 25 motors. It would cost less, likely weigh less, and be enough power. Higher mah packs will give longer flight times and run cooler, and cooler running packs last longer.
Here is a decent read to get started - it's geared toward electric twins, but same principle just double:
http://www.modelairplanenews.com/blo...win-electrics/
Here is an E-flite twin engine electric plane that is a little more than half the weight of what you're looking at. I would read the manual and basically copy the power system, X2 (meaning copy the way things are hooked up; copy the power system X2 if you decide on the Power 25 or 32, etc). You would get better performance though due to the weight, so the Power 25 would likely be fine. The manual should show you how to rig up your power system. Again, just double the wiring setup.
http://www.e-fliterc.com/Products/De...ProdID=EFL4550
10-31-2013, 04:52 PM
#6
Yes those two batteries will not do the job. You can use one for each motor, for a total of (4) per flight.
I ran a few number through this calc program.
http://www.ecalc.ch/motorcalc.htm?ecalc&lang=en
I used this motor with a 10X6 4 bladed prop
http://www.hobbypartz.com/96m603-big...826-870kv.html
Battery
http://www.hobbypartz.com/98p-25c-3300-4s1p.html
ESC
http://www.hobbypartz.com/proton60aair.html
It shows that each motor will pull about 40 amps with with 520 watts and 5.5 pounds of thrust. It lists the flight time of just under 5 minutes. Well, it said I would have 12 minutes of flight time on one of my setups, but got over 30 with good throttle management.
I have (2) of the Tacon 60's, (2) of the 10's, one of the 46's. They have never given any trouble, lots of power.
Take all of this with a grain of salt, the information is worth every penny you paid for it
. You have a big project. do lots of reading to understand the E power.
Buzz.
I ran a few number through this calc program.
http://www.ecalc.ch/motorcalc.htm?ecalc&lang=en
I used this motor with a 10X6 4 bladed prop
http://www.hobbypartz.com/96m603-big...826-870kv.html
Battery
http://www.hobbypartz.com/98p-25c-3300-4s1p.html
ESC
http://www.hobbypartz.com/proton60aair.html
It shows that each motor will pull about 40 amps with with 520 watts and 5.5 pounds of thrust. It lists the flight time of just under 5 minutes. Well, it said I would have 12 minutes of flight time on one of my setups, but got over 30 with good throttle management.
I have (2) of the Tacon 60's, (2) of the 10's, one of the 46's. They have never given any trouble, lots of power.
Take all of this with a grain of salt, the information is worth every penny you paid for it
. You have a big project. do lots of reading to understand the E power.Buzz.
10-31-2013, 06:27 PM
#7
Senior Member
Four blade props can be hard to come by. Three blades have a somewhat limited size and pitch range.
A 15-20 pound AC - - -
100W per pound is what I'd use for minimum power calculation.
If this used a single motor, I'd likely use at least a 5000mah battery.
With what you have in mind, I'd think 4 3300mah to 4000mah batteries might do.
I'd likely use a minimum of four cell lipo's, and possibly a higher cell count, depending on the motors.
Using two instead of four batteries extends the wire lengths between the ESC and battery.
I'd also use opto isolated ESCs, and a separate battery or two for the RX and electronics.
A 15-20 pound AC - - -
100W per pound is what I'd use for minimum power calculation.
If this used a single motor, I'd likely use at least a 5000mah battery.
With what you have in mind, I'd think 4 3300mah to 4000mah batteries might do.
I'd likely use a minimum of four cell lipo's, and possibly a higher cell count, depending on the motors.
Using two instead of four batteries extends the wire lengths between the ESC and battery.
I'd also use opto isolated ESCs, and a separate battery or two for the RX and electronics.
