gld2

Can anyone tell me how much current a speed 400 7.2 volt with a direct drive 6-3 prop on 12 volts will draw.

Gary

smokingcrater

on 12 volts? (10 cell pack) probably about 10-12 amps before the motor smokes... (well, maybe it would be ok at that, but 10 cells is alot for it.) are you talking 12v from a pack fresh off the charger like an 8 cell nimh pack usually is, or something that is rated at 12v nominal, which would be a 10 cell pack? on an 8 cell pack a speed 400 on a 6-3 prop will probably draw around 6-8 or so.

skater_719

My Feedback: (4)

ya, thats really pushing one of those little speed 400s, i wouldnt go too much over the recommended cell count which is prolly around 7 or 8.

gld2

Here's the story. I found this electric C-130 plan in dfx format. It calls for four speed 400's direct drive 6-3 props and a 10 cell nicad. I bench checked one motor for amp draw and it showed 9 amps. So 4X9=36 amps total. Called Castle Creations and got a 55 amp speed controller, and Battery's America for a 2500 10 cell nicad. This gave me aroud 3 to 3.5 min flights. On flight number 13 it spun in and destroyed the aircraft. So now I have built a new one and wanted longer flights, so I installed ball bearing gear boxes 3-1 ratio , 4 blade 10-8 GWS props. I now show 28 amp draw which will increase flight time. Also purchased a 3 cell li-poly 7500 ma battery. Longer flight time lighter battery. HA HA. It did not have enough thrust to maintain flight.
Tried 9-6 two blade props, no go. Tried 8-4 props. It would fly ,but not as good as the 6-3 direct drive. BTW both planes weighed 5.9 pounds. Back the the drawing board!!!!!!!!!!!!!!
OK now I am back to direct drive 6-3 props. Thought I would recheck current draw and am showing over 60 amps on one motor. Do not understand what is happing here.

I was flying ok before buy Iam afraid to fly as I do not want to burn up my speed controller.
The first aricraft can be seen on my web page.

http://www.gldpages.com/C130.htm

Any suggestions would be appreciated.

Time Pilot

If I did it right, motocalc suggests that you're running at around 10 amps and 112 watts.

I know that some people fly 400's with 3C LiPo's. They don't fly at full throttle much, the motors don't last forever, but the 400's aren't that expensive.

Something I don't understand is that flyers will push the little 300's to 9.6 volts. I would assume that a 7.2V 400 would easily handle 10.8V. 12V is taking the relationship up to the next level though.....

Billy Haynes

I just came across this thread. I've been fly'n a 7.2V, APC 6x4 prop on 3s lipo's. I have..... say 15 flights on this set up. I only expect 25 flights before the motor is done for. It kind of depends on how well the battery will supply voltage under load. I usually fly with a 3s 1050 Apogee pack. I just did some quick test with a Medusa Power Analyzer. With the 3s 1050 pack it only draws 8.5-9 amps, 80-90 watts (which fly's the Python rather well). Now with a 3s 2480 pack it draws 11.5 amps, 130 watts (more power, yes, but the motor wouldn't last long).
At 6lbs AUW your asking each S400 to pull 24oz..... I feel that’s a lot for a DD 400. I feel geared would be better, more thrust but at the cost of prop speed. I don't understand the 60amps on one motor. Even if you meant to say 60amps w/all four, that’s 15amps each! Could it be possible that one or more motors are bad (shorted)? That's a nice battery pack you got there (7500 3s). It could supply power to some better motors. Here's what I'd try-- (4) 450 turbo, 3:1, APC 9x9, 3s 7500, motors wired in parallel. Here's the motor I'm talk'n about, look for Permax 450 turbo-- http://www.multiplexusa.com/product_fs.htm
I have two of these motors I plan to use in a twin, but haven't got around to it yet. I've heard these motors are good on 3s only when geared 3:1 to keep the amps down. I don’t know the plane spec’s (W.S./ W.A.) but it doesn’t look to have a lot of wing area for the weight (=high wing loading). Four Graupner Cam 10x8's might be a good combo with only a slight loss of airspeed. The down side would be 9x9 42amps vs 10x8 50amps, but would work if you didn’t fly WOT the whole flight. Just some of my thoughts......

bobbart

I'm building a C-130 with four 400's. I also customize the props, 4-blades 5.5 x 3. As of now, I'm only at 5% competed and did not test the motors at full speed with those props.

Bob

HitecRedneck

Using a long can speed 400 motor will take care of the extra voltage from a 10 cell pack. I'm using 11.1 1500 mah packs without problems