Hacker B50 not producing acceptable thrust
04-13-2005, 12:25 PM
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Hacker B50 not producing acceptable thrust
Hey all,
I am running a Hacker Brushless B50-10L w/ 5.2:1 Planetary Gearbox on 14 SR Batteries 3000H NiMH cells turning a 14x10 prop (the ESC is a 40 AMP Master 40-O-Flight). This setup should produce at least 5.5 lbs of thrust, but I am only getting 2 lbs out of it [e-calc and motocalc gave me a max of 7.2 lbs]. I have no idea what the problem is, but I am going to check voltage and amperage pull tonight. Anyone who might be able to help, I would greatly appreciate it. This is for a Competition at Rensselaer Polytechnic Institute, in Troy NY.
By the way, I have already ruled out end point adjustment and ESC programming (I think :-) )
Thanks,
Phil Bracken
I am running a Hacker Brushless B50-10L w/ 5.2:1 Planetary Gearbox on 14 SR Batteries 3000H NiMH cells turning a 14x10 prop (the ESC is a 40 AMP Master 40-O-Flight). This setup should produce at least 5.5 lbs of thrust, but I am only getting 2 lbs out of it [e-calc and motocalc gave me a max of 7.2 lbs]. I have no idea what the problem is, but I am going to check voltage and amperage pull tonight. Anyone who might be able to help, I would greatly appreciate it. This is for a Competition at Rensselaer Polytechnic Institute, in Troy NY.
By the way, I have already ruled out end point adjustment and ESC programming (I think :-) )
Thanks,
Phil Bracken
04-13-2005, 01:29 PM
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RE: Hacker B50 not producing acceptable thrust
I just ran the numbers through P-Calc at www.flydma.com, and they jive pretty close with what you're expecting.
First, make sure you have what you think you have. Wrong gearbox, wrong wind motor, wrong prop... Any of these will drastically affect the real-world output.
My suspicion is battery output. They're not able to hold up to the 40+ Amp draw that combo should be making, and the voltage is dropping drastically. With 14 cells, they've got to drop to less than .5V per cell to get the low-voltage cutoff to kick in.
The solution is to get a better battery pack. I was not aware that SR, if it's the SR Batteries I'm thinking of, dealt with NiMH batteries. Last I checked, they were NiCd only, and would NEVER touch NiMH cells.
First, make sure you have what you think you have. Wrong gearbox, wrong wind motor, wrong prop... Any of these will drastically affect the real-world output.
My suspicion is battery output. They're not able to hold up to the 40+ Amp draw that combo should be making, and the voltage is dropping drastically. With 14 cells, they've got to drop to less than .5V per cell to get the low-voltage cutoff to kick in.
The solution is to get a better battery pack. I was not aware that SR, if it's the SR Batteries I'm thinking of, dealt with NiMH batteries. Last I checked, they were NiCd only, and would NEVER touch NiMH cells.
04-14-2005, 07:47 AM
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RE: Hacker B50 not producing acceptable thrust
Well...I figured it out. I am obviously not up on my wiring knowledge, because I had the two 7-cell packs wired in parallel, not series. Thanks for the suggestions!
