Help! Radial Twin C-pack

chris398mx

Master member
Does anyone know how heavy of a plane can be flown with the Radial twin C-pack? I am building a scratch build bomber with a 72 inch wing span and the weight is adding up fast. I am not sure the twin C-pack will pull around this plane. Or does anyone know how much thrust one C-pack motor can produce on 3S or 4S? Any help is appreciated.
 

mach1 rc

Master member
Oh
Does anyone know how heavy of a plane can be flown with the Radial twin C-pack? I am building a scratch build bomber with a 72 inch wing span and the weight is adding up fast. I am not sure the twin C-pack will pull around this plane. Or does anyone know how much thrust one C-pack motor can produce on 3S or 4S? Any help is appreciated.
Oh and what bomber are you planning on doing?
 

Zetoyoc

Elite member
Does anyone know how heavy of a plane can be flown with the Radial twin C-pack? I am building a scratch build bomber with a 72 inch wing span and the weight is adding up fast. I am not sure the twin C-pack will pull around this plane. Or does anyone know how much thrust one C-pack motor can produce on 3S or 4S? Any help is appreciated.

I do not have many props for my new c pack radial. and I do not have a 4s battery yet. but I did build and calibrate a test stand and have tested what I have. My best thrust so far is 1150g thrust pulling 23.3 amps using an APC 9x4.7sf prop and 3s battery. there is a lot more in this motor for sure. I just need more props and batteries to test :) I have a couple larger props on order, Ill let you know how they do when i get them.
 

chris398mx

Master member
Oh

Oh and what bomber are you planning on doing?

It is a 1930's B-10 bomber.

B-10 bomber.JPG


Here is what I have so far.

IMG_5406.jpg

IMG_5419.JPG

IMG_5420.JPG
 

chris398mx

Master member
I do not have many props for my new c pack radial. and I do not have a 4s battery yet. but I did build and calibrate a test stand and have tested what I have. My best thrust so far is 1150g thrust pulling 23.3 amps using an APC 9x4.7sf prop and 3s battery. there is a lot more in this motor for sure. I just need more props and batteries to test :) I have a couple larger props on order, Ill let you know how they do when i get them.

So if I have 2 that is 2300g thrust. Do I need at least a 1:1 ratio thrust to weight to get it off the ground?
 

BATTLEAXE

Legendary member
Does anyone know how heavy of a plane can be flown with the Radial twin C-pack? I am building a scratch build bomber with a 72 inch wing span and the weight is adding up fast. I am not sure the twin C-pack will pull around this plane. Or does anyone know how much thrust one C-pack motor can produce on 3S or 4S? Any help is appreciated.
Your twin C pack on 4s will draw a lot of amps compared to a 3s, also depends on the props you plan to use as well. What were you thinking of using for the props and ESC?
 

chris398mx

Master member
Your twin C pack on 4s will draw a lot of amps compared to a 3s, also depends on the props you plan to use as well. What were you thinking of using for the props and ESC?
The ones that came with the Radial C pack.....35A esc's. supposedly you can use a 10 inch prop on 4S, but the motor gets pretty hot when I tried it. So if I use 4S, I will likely use a 9 inch prop. 3S a 10x45 SF.
 

BATTLEAXE

Legendary member
The ones that came with the Radial C pack.....35A esc's. supposedly you can use a 10 inch prop on 4S, but the motor gets pretty hot when I tried it. So if I use 4S, I will likely use a 9 inch prop. 3S a 10x45 SF.
There is a lot of faux radial motor to get the airflow around. If the prop you have on there now is a 10x45 then that would be the smallest I would go. You don't need a high pitch on 4s either, the higher rpm will take care of that. Plus I am sure if your test was static while inside the faux radials you weren't getting sufficient airflow to cool the motor, that's probably why it got hot
 

chris398mx

Master member
There is a lot of faux radial motor to get the airflow around. If the prop you have on there now is a 10x45 then that would be the smallest I would go. You don't need a high pitch on 4s either, the higher rpm will take care of that. Plus I am sure if your test was static while inside the faux radials you weren't getting sufficient airflow to cool the motor, that's probably why it got hot

It was on a different plane with a single motor. My version of a master series spitfire.
 

Zetoyoc

Elite member
i have a 9x7x3 and a 10x6e on the way shoudl be here monday.

to fly you need a lot less than 1:1 ratio power to weight. to take off or loop or other aerobatics needs a bit more. :)

here are some figures i quickly searched for a moment ago. take with a bit of salt. i do not know of thier validity

50-70 watts per pound; Minimum level of power for decent performance, park flyer/slow flyer models
70-90 watts per pound; Trainers and slow flying scale models
90-110 watts per pound; Sport aerobatic and fast flying scale models
110-130 watts per pound; Advanced aerobatic and high-speed models
130-150 watts per pound; Lightly loaded 3D models and ducted fans
150-200+ watts per pound; Unlimited performance 3D and aerobatic models


if i assume 12.4 v (likely lower) on my best test with the 9x4.7sf and 3s. it was 288 watts
 
Your twin C pack on 4s will draw a lot of amps compared to a 3s, also depends on the props you plan to use as well. What were you thinking of using for the props and ESC?
So I just bought master airscrew three blade light weight 11x10 props for my twin c pack on a 4 cell 3300mah and had a heat up problem. Both motors got super warm. Should I switch back to a two blade or is it because my test was static? I didnt fly it I just tested it in my backyard.
 

Matagami Designs

Master member
So I just bought master airscrew three blade light weight 11x10 props for my twin c pack on a 4 cell 3300mah and had a heat up problem. Both motors got super warm. Should I switch back to a two blade or is it because my test was static? I didnt fly it I just tested it in my backyard.

I think you might be putting way too much load on those motors. I burnt up my 1st c pack on 3s 10x7 two blade prop during the summer. It depends on many factors though like ambient temperature how much cooling and throttle % too. I ran the same motor on a 10x7 3 blade in the fall though and was fine for a few shorter flights.