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Ace Hobby . Esprit Model . Thunder Power RC

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e-Electric Conversions > Hirobo Lama Electric - what motor?
 
 
Surri
Heliman
Location: Nidwalden, Switzerland

I finally decided to go electric with my Hirobo Lama after several continuous and uneventful days where I was struggling to bring my OS 32HSX alive. So I guess by know I read most what's being recommended as suitable brushless motor for my Hirobo Lama; replacing the nitro engine while keeping the original clutch. I discovered the “Rules of Thumb” stating 100W motor power per lbs helicopter weight and mathematically calculated engine power requirements based on weight, torque, rotor rpm, gearing, voltage and; compared what has been published in several forums. And this is exactly where I am today.....lost !!!! As example, some folks seem to be very happy with a small Hacker A30-12XL @720rpm/v; other stated that only a "pure power" Hacker C50-12XL @1350rpm/v will make it.



So may I ask what is your recommendation / field experience ?

Cheers – Surri
03-27-2007 Over year old.
 
 
Tap or Snap
Senior Heliman
Location: Springhill, Fl

Quote: “Rules of Thumb” stating 100W motor power per lbs. You can go to 50 or 60 watts per pound for a scale bird. As for what kv rating to use somewhere between 565 and 800 will work. Try to optimize your gear ratio so your controller is operating at 80-90%, makes for less heating in the controller, some may disagree but I like to get the gear ratio close to give me the headspeed I want as opposed to turning down the controller percent to compensate for a wrong gear ratio. Some controllers dont seem to mind if you dial them down to lower the headspeed. Since this is a scale bird you dont need a screaming headspeed, 1500-1600rpm should suffice, the 100w per pound is for the hard 3-d guys.

Jeff
03-28-2007 Over year old.
 
 
Surri
Heliman
Location: Nidwalden, Switzerland

E-Lama

Thank you for reconfirming.....this helps to select the proper motor.

Cheers - Surri
03-28-2007 Over year old.
 
 
R.J.
Senior Heliman
Location: SF bay area, CA USA

Hi Surri,

We used the 50 watts per pound figure and came up with the Hacker A30 12XL at 770 kv on 6S at about 8.5 lbs ready to fly. Power is fine for scale. 3D guys would say it's anemic. Whatever you do, try to keep it as light as you can to keep the disc loading from being unreasonable. You may need more power if you plan to run a 3 blade head. I have not tried the 3 blade with the Hacker A30. Let us know what you end up trying.

Regards,
Rick Jow
03-28-2007 Over year old.
 
 
Bell Bloke
Key Veteran
Location: England

Hi Surri,
Just browsing the conversion section and see that the Hacker you intend using is a 720rpm per volt unit with your Lama, and this you plan to run on 10 cells. I am not familiar with the size of this motor but at a cold calculation level I think that 10 cells will give a too higher headspeed. I would suggest that you run a 2x 4cell set-up which will give you a far nicer flying model. The target headspeed you want to be at is 1500-1800rpm. Your set-up would put you well over 2200rpm and this could put you in danger of stripping the main gear if you are running 550mm 110gram blades, which I would recommend you do when running the 2 or 3 bladed head.
A simple calculation here is:

Number of cells
Multiplied by
4.2
Multiplied
Rpm per volt...720
Divided by the gear ratio....ie how many times the pinion gear goes around to 1 turn of the main rotors.
Then finally take off 20% mechanical loss and then you should end up with your headspeed....simple

Hope this helps, all the best Bell Bloke
Here's my electric Lama on its maiden 2 years ago.

03-31-2007 Over year old.
 
 
Surri
Heliman
Location: Nidwalden, Switzerland

Lama E-Conversation

Hi Guys,

Thank you all for your great suggestions. I will now review all your thoughts and get back to you with my selected way forward....motor.

Thanks again and have a great day / night.

Cheers - Surri

04-05-2007 Over year old.
 
 
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e-Electric Conversions > Hirobo Lama Electric - what motor?
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