12S power systems ideas and options

[rcbirk21]

everyones talking about putting the motor in a 27%er...if its as much power as manta talks about on a 30%er, that would be nuts. im always looking for a ken alternative for a 50ccer, especially since i just got the q80 for my 87 because it was the best option out there. may have to get another 50ccer to put a ken special in

 

[Aeroplayin]

Yep, we're talking about what some consider silly power, but is is what keeps some of us interested in the hobby. But you have to understand that we're propping down on the 78 inch airframe, which means less power, less heat, and more efficiency.

With this motor, we're not really adding much more weight than some setups with what we consider to be marginal power. This setup that I'm talking about is about the same Watts per pound as my EF 60 EXP on 6S and a 16x8 PJN on the DM4315-480, my EF 48 inch EXPs with the DM2820-750 on 4S with a 14x7 APC, and my 3DHS 74 Edge 540 with an A60-7S on 10S with the 21x10 Falcon... 250 to 275 Watts per pound, if the motor will come in as light as reported.

AND... the same Watts per pound as this motor to 5200W with a 24x12 PJN on 12S on a 19 pound plane.

 

[rcbirk21]

i guess i just have a different view on power setups, not that its an issue. im not just about watts per pound, i also like an airframe to be light for its size. you add watts, you also add weight, and ive found that i like lighter planes. its not marginal power, its adequate power. it doesnt get you into trouble, it allows the plane to fly much smoother, and just feels more correct in the air to me. to each his own, the great part about the hobby.

 

[Aeroplayin]

i guess i just have a different view on power setups, not that its an issue. im not just about watts per pound, i also like an airframe to be light for its size. you add watts, you also add weight, and ive found that i like lighter planes. its not marginal power, its adequate power. it doesnt get you into trouble, it allows the plane to fly much smoother, and just feels more correct in the air to me. to each his own, the great part about the hobby.

Not really. You don’t add weight when you add Watts because Watts is only a product of volts and Amps, which means changing the cell count or moving up and down with prop sizes. I can add cell, add Watts, and reduce Amps without changing the weight. You add weight when you add battery capacity, or keep the same capacity and add cells. If you gain Watts, but reduce Amps, you don't have to trade off capacity weight if you do a little math.

I can, in certain instances, add Watts, add cells, and get the same flight time on the same plane. I programmed the PropEngine to help novice electric power users calculate how cell count, Kv, motor efficiency, and prop size, can be manipulated to get the power they are looking for. Feel free to use it. http://rcwebclub.com/PropEngine.aspx

For Motrolfly motors and PJN props, use 82% in the Kv Efficiency field and 0.96 in the Prop K field.

Also, although power is synonymous with Watts in these setups, thrust and torque will be important to 3D pilots since full stall maneuvers requires high torque and thrust, and we can even create scenarios where higher Watts means lower torque.

An example is talking a motor with a 216Kv, and using a 20x8 prop on 12S and 3300mAh batteries, then switching to a 21x10 prop with 10S and 4000mAh batteries. The motor is the same, and the 2x 6S batteries are actually 33.7 oz, and the 2x 5S 4000 batteries are 35.6 oz.

The 20x8 on 12S will produce 2855W and 65A, with 2.18 lb-ft of torque and a pitch speed of 60 mph at 7895 RPMs. The 21x10 will produce 2510W and 69A, but 2.31 lb-ft of torque, and a pitch speed of 62 mpg at 6575 RPMs.

 

[gyro]

Not really. You don’t add weight when you add Watts because Watts is only a product of volts and Amps, which means changing the cell count or moving up and down with prop sizes. I can add cell, add Watts, and reduce Amps without changing the weight. You add weight when you add battery capacity, or keep the same capacity and add cells. If you gain Watts, but reduce Amps, you don't have to trade off capacity weight if you do a little math.

I can, in certain instances, add Watts, add cells, and get the same flight time on the same plane. I programmed the PropEngine to help novice electric power users calculate how cell count, Kv, motor efficiency, and prop size, can be manipulated to get the power they are looking for. Feel free to use it. http://rcwebclub.com/PropEngine.aspx

For Motrolfly motors and PJN props, use 82% in the Kv Efficiency field and 0.96 in the Prop K field.

Also, although power is synonymous with Watts in these setups, thrust and torque will be important to 3D pilots since full stall maneuvers requires high torque and thrust, and we can even create scenarios where higher Watts means lower torque.

An example is talking a motor with a 216Kv, and using a 20x8 prop on 12S and 3300mAh batteries, then switching to a 21x10 prop with 10S and 4000mAh batteries. The motor is the same, and the 2x 6S batteries are actually 33.7 oz, and the 2x 5S 4000 batteries are 35.6 oz.

The 20x8 on 12S will produce 2855W and 65A, with 2.18 lb-ft of torque and a pitch speed of 60 mph at 7895 RPMs. The 21x10 will produce 2510W and 69A, but 2.31 lb-ft of torque, and a pitch speed of 62 mpg at 6575 RPMs.

Very interesting calculations! It's amazing we can break this all down so simply

 

[rcbirk21]

Not really. You don’t add weight when you add Watts because Watts is only a product of volts and Amps, which means changing the cell count or moving up and down with prop sizes. I can add cell, add Watts, and reduce Amps without changing the weight. You add weight when you add battery capacity, or keep the same capacity and add cells. If you gain Watts, but reduce Amps, you don't have to trade off capacity weight if you do a little math.

I can, in certain instances, add Watts, add cells, and get the same flight time on the same plane. I programmed the PropEngine to help novice electric power users calculate how cell count, Kv, motor efficiency, and prop size, can be manipulated to get the power they are looking for. Feel free to use it. http://rcwebclub.com/PropEngine.aspx

For Motrolfly motors and PJN props, use 82% in the Kv Efficiency field and 0.96 in the Prop K field.

Also, although power is synonymous with Watts in these setups, thrust and torque will be important to 3D pilots since full stall maneuvers requires high torque and thrust, and we can even create scenarios where higher Watts means lower torque.

An example is talking a motor with a 216Kv, and using a 20x8 prop on 12S and 3300mAh batteries, then switching to a 21x10 prop with 10S and 4000mAh batteries. The motor is the same, and the 2x 6S batteries are actually 33.7 oz, and the 2x 5S 4000 batteries are 35.6 oz.

The 20x8 on 12S will produce 2855W and 65A, with 2.18 lb-ft of torque and a pitch speed of 60 mph at 7895 RPMs. The 21x10 will produce 2510W and 69A, but 2.31 lb-ft of torque, and a pitch speed of 62 mpg at 6575 RPMs.

you would put the same motor in a 78" plane as i would in a 92" plane. i think that is weight that is in excess of what i would make for a setup. i understand p=v*i, but that is only ideal and whenever people go up in cell count they tend to go up in power. like i said, to each his own. im not trying to argue that you are happy with your setups

 

[Aeroplayin]

Sure, but I want to make sure that guys reading this understand that the relationship between these variables can be used in a simple way to find the power, prop, cells, motor Kv, and current, that makes sense for them. The beauty of the motors I get from Subsonic is that they are light, powerful, and run cool. That means a lot to me because my son beats the pee out of his (and my) 3D planes here in the Florida heat. If I can get 275 Watts per pound from Ken's motor that was designed for a bigger plane but weighs the same as a 225 Watts per pound power system that was designed for the smaller plane, then I'd go with the more powerful motor because it will operate more efficiently. If Ken's motor is as light as Matt said, then it can mount and balance as good as a less powerful motor, and power the plane during the Florida summer without breaking a sweat.

 

[wedoitall]

I've learned a ton reading Aero's post and still learning.

All I can say is if this motor works out to give me the same watts per pound that I get in my 60"EXP's, That may change a lot of plans I had in the next few months.

 

[skibum44]

Subbed... Wow the new subsonic 50CC looks great. Looks like a bigger brother to my 12s 4330s. If it performs anything like it, it will be a power house cool running mamajamma. I have been playing around with 12s setups for some time and it has proven it self to be the coolest running systems for 30CC planes. If you don't mind the 2 pack battery applications it has many upsides. To get the power I am producing @ 72A, a 6s setup would need to produce 144A, 8s wold need 108A, and 10s would need 86.4A. Another benefit is battery sharing... The 6s 2600 batteries I use in my 12s 71" slick I also use in a 500 pro, 57 Extra, and 60" Extra for floaty setups. Also, 78" class birds could also use 2x 6s 3300s in combination with a 57"-60" versatile setups. I use the 6s 3300s in combination with a 600pro, 57" extra, and a 60" extra and hope to have a 78" Extra "EXP", hint hint. It saves me a bunch of money not having to invest in all different flavors of batteries. I intend to use the 6s5000s between a 50cc 3D bird running the new 50cc subsonic motor and a 700 class hell.

 

[wedoitall]

How much run time are you getting out if the 6s 2600 in your extra? Also do you know what your AUW is on the extra?