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Sig Riser 100 with HK Propdrive 35-48

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Sig Riser 100 with HK Propdrive 35-48

Old 10-26-2021, 06:06 PM
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Bigshark
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Default Sig Riser 100 with HK Propdrive 35-48

The last time I built an electric sailplane the brushed Kyosho Endoplasma geared 3.8 to 1 on 7 nimh cells was the best budget power system on the planet for a 1.5 to 2 meter sailplane. I thought nothing in the modern world of lipos and brushless could possibly be that heavy...........Then based on nothing but assumptions I bought a Propdrive 35-48 (since it would fit the nose and bigger is always better right?) I also bought a 25C 3S 5000 lipo from HK to power it. The power results are impressive. I just tried those items with a 15x6 Aeronaut folder. At full throttle it was pulling 52amps and turning 9300 rpm. Based on the pull this combo will take my Sig Riser 100 vertical. I may prop down a bit because the motor is supposed to go 55amps max and it did get king of hot on my bench runs. The bigger issue is the weight. When exactly did lipos of the same capacity start weighing as much as round cells. Sure I should've checked the weight before I bought but good grief those Turnigy lipos are heavy!

Live and learn......

Old 10-26-2021, 07:20 PM
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speedracerntrixie
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My question is why on earth do you need a 5000mah battery? I fly my 3.5 meter Supra with an 850mah battery. My suggestion with E powered sailplanes is to arrange the radio gear and use the smallest battery that gets you a CG of 35% MAC.
Old 10-26-2021, 10:10 PM
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That's a good question. The answer is that it's the first lipo I've ever bought and I assumed they'd all be tiny compared to the car packs I used to use. I could cut the battery weight in half with a 2700 or 2200 3 cell and I may do that next time I need parts.

Last edited by Bigshark; 10-27-2021 at 07:47 AM.
Old 10-27-2021, 04:02 AM
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Depending on how you want to fly, you could easily go as small as 1000mah. The type of flying I do with mine is referred to as ALES ( altitude limited electric sailplane ). It’s a form of competition that allows for a 30 second motor run followed by a 9.5 minute thermal flight. My 850 pack provides plenty of power for that but if I wanted to cruise around some under power then it would prove too small. Bottom line is that how you fly will determine the size of battery.

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