pt40crasher

Newb here. I am looking to install an AXI 2808/20 Motor with Jeti Advance PLUS 30 amp controller with a 3S 2100mAh Thunder Power LiPo in a GWS Formosa. Does this sound right? This Electric power rating stuff is a little nebulous. Thanks in advance.

Crasher

Dr Kiwi

This 10x6 GWS HD takes it to just short of the max amp limit (22A/60secs)


Motor: Model Motors AXI AC2808/20; 1490rpm/V; 1.3A no-load; 0.105 Ohms.
Battery: Thunder Power TP2100 (ProLite); 3 cells; 2100mAh @ 3.7V; 0.018 Ohms/cell.
Speed Control: Castle Creations Phoenix 25; 0.0065 Ohms; High rate.
Drive System: Direct; 10x6 (Pconst=1.07; Tconst=1) direct drive.
Airframe: Anything you want.
Conditions: 600ft above Sea Level, 29.92inHg, 68°F

Motor Amps = 20.6
Motor Volts = 9.9
Input (W) = 202.7
Prop RPM = 7354
Thrust (oz) = 23.4
PSpd (mph) = 41.8

Trogdor the Burninator

That will work but is a load of power for that plane... If you're used to fast powerful planes though it should be real fun. Only thing is at that weight it won't come in for the floaty landing. I used a smaller axi motor on mine and going from a 1320 3s pack to a 2100 really made a difference in the lower speed stuff. normal sport flying was great and it probably handled the wind better too.

Dr Kiwi

I wondered about a 79g motor and 144g pack on a light (425g/15oz max) plane like that too!

pt40crasher

Thanks for the replies. I have re-cosidered. I think I'll be using a E-flite 400 920 kv motor, 35A Phoenix speed control and the Thunder Power 3S 2100mAh LiPo. Is this a more reasonable option.

Dr Kiwi

That saves you 21g anyway. I agree that a larger ESC is usually a good safe thing to do, but 35A on a 13A max motor seems excessive. A Thunderbird 18 would be plenty and you could probably even get away with a PH10.

cptcrusty1

Dr. Kiwi, Maybe you could help me out a little too.... PLEASE

I'm flying a Zagi 400xs. I asked the Tower Hobbies people what brushless upgrade to use and I end up with a dead motor. The DC motor is a speed 400 running backwards (stock from Zagi). Their Brushless upgrade information only tells me that its a 3000kv motor. Here's what I picked....

Known.
35amp Electrifly Brushless ESC w/BEC
9.6v, 2000mah 2/3 C (I think this means sub c, right?)

5x5 prop.

I put the Ammo inrunner (Tower said it would work) 28-35-3900KV on all that equip. box says Constant is 22amp, max surge is 45 amp. My speed control is rated at max 40 amp surge, however, since I'm using such a small prop, I'm not thinking its going to work that hard...

After installation, it ran like a scalded ape. I got 3 good flights out of it, the 4th was sluggish, the 5, the motor wouldn't turn.. The prop just kept flipping back and forth. I pulled the motor and can hear something rattling around in there... Could I have burned up the motor somehow? Tower still says its the right motor and that its defective....

Any ideas?

Thanks.
Crusty

Dr Kiwi

According to Motocalc that 5x5 on 8-cells should have been well within the motor's limits - something is amiss! Perhaps these Ammo motors are not as good as they should be?


Motor: GPMG5200- AMMO 28-35-3900KV; 3900rpm/V; 1.8A no-load; 0.24 Ohms.
Battery: Sanyo CP-2400SCR (25C); 8 cells; 2300mAh @ 1.2V; 0.0053 Ohms/cell.
Speed Control: Castle Creations Phoenix 45; 0.0026 Ohms; High rate.
Drive System: Direct; 5x5 (Pconst=1.47; Tconst=1) direct drive.
Airframe: Anything you want.

Motor Amps = 15.8
Motor Volts = 8.9
Input (W) = 140.7

Prop RPM = 14498
Thrust (oz) = 8.2
PSpd (mph) = 68.6


Did you actually check the current draw?

cptcrusty1

Uh..... current draw? Uh.... I don't know how to draw current.... I'm like the other guy.. .ignorant. I can read... it tells me the limits. Ok... Here's the latest twist to this story...

Just for grins, I hooked up the motor, esc, battery, and turned everything on..... on holy.. XXXX, the dumb thing was working.... I had to add extensions to the motor since the leads are so short... could one of the extentions been bad, i.e., bad connection causing the motor to freak out?

Could this be kind of like your car battery when its corroded? You don't get good juice to the starter, thus it doesn't start? When I reconnected the motor, it was without the extentions.....