pikeman401

My Feedback: (1)

I'm the guy who is putting an Astro 05 on an Electrosteak. Well Rather than post a lot of threads I decided to down load Motocalc. So I pluged in the numbers ----geared 2.38:1 . The recomended bat pack was a 3X1950li4p. So I assume that would be a 3S4P or a 11.1 volt 7800mah batt pack. Considering the weight of the packs ( probably over 16 oz) doesn"t that seem a little much? They recommend a 10/ 6 prop. I can live with that. In another thread someone said that my astro 05 with gearbox would pull 20 amps, somewhere else it says 30 amps. ???? Would I be better off going direct drive? A 10 in prop is about as long as I can go.

BadSplice

My Feedback: (1)

if the motor only pulls 20A, then a 3s1p 2000mah lipo would be plenty. that battery would probably be ok if the motor drew up to 30A but in that case, you might want to go with a 3s2p1500 (3000 total)

Matt Kirsch

My Feedback: (21)

Rather than pay attention to the pack it recommends, pay attention to the numbers it generates. You can choose your own pack based on the numbers. Motocalc should tell you exactly how many Amps the motor will be drawing on a 3S (11.1V) LiPoly pack with any 10" prop you choose.

If you're going to be making extended full throttle runs, which is what an Electrostreak is meant to do, you don't want to be running right at the ragged edge of a LiPoly pack's rated capacity. Build in a little safety margin. Yes, they claim the packs can run from full to empty at that rated capacity, but that's in perfect conditions. Our conditions are far from perfect, and the packs' lifespan will certainly be shortened.

A pound isn't bad for that much capacity. That's less than what the equivalent 3300mAh NiMH pack would weigh, and it gives you well over double the duration. You could probably drop that pack down to a 3S2P and still be safely within the pack's capabilities for long speed runs, depending on what pack you choose.

I'm guessing Motocalc is using ThunderPower packs, which are now rated at 10C. Two packs in parallel would give you 39 Amps of peak current capability and 3900mAh of capacity. That's plenty for a speed plane with a peak current of 20, or even 30 Amps.

pikeman401

My Feedback: (1)

The bat pack I have is a 3S2P 1500 Dymond pack. I went with this after Matt said I would smoke a 3S single pack if I tried it. Astro 05 draws too much current. From what you said it sounds that this combo should work. I will play around with some different props and playaround with motocalc. I just downloaded it last night and starting out at the learning curve. I may take the box off and try it direct drive. Maybe an 8X4 or 8X6 prop. The plane comes in at 33 oz. I assume with direct drive I may gain speed but loose power? I'll go back and try motocalc again. Oh unfortunatly that 33 oz includes the 1 oz of lead I had to put in the tail. That Astro is a heavy motor.