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Old 03-16-2004, 12:22 AM
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Spaceclam
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Default RE: Building a DraganFlyer - need to mix speedcontrollers - HELP

you are not biting off more than you can chew. i just turned 14 and i managed to get it to fly while i was still 13. just a couple things. don't order the props yet, and make sure that you get at least a 4 channel receiver and a 4 channel transmitter. do you know how to hook up the veetails? sence you dont have mixers with the cheaper radio you can do a mix on the veetails to bring down the atvs some as 30% travel is by far too much. how big are you making this? i would advise you to figure out a target weight first. if you are going to go smaller the draganflyer blades will do great but you have to gear them down to about 1000 rpm or less before you have to reinforce them a bit with carbon fiber laminate or something. if you plan on going over a pound, go with the smaller blades. i know it doesn't seem logical as it will make your rotor disk loading higher and make it less controllable but those draganflyer props can not handle the rpms needed to generate enough lift to power a model much heavier than 1 lb with their construction and specifications. once you add up the weight of all the components (allow about a half ounce at least per speed controller if you are going real cheapo) find a motor gearbox match that will suit your needs. www.balsapr.com has a good list of motors and they all have statistics for props and voltages so it will really help. it tells you thrust, current draw ad different voltages with diferrent props. those stats are only accurate for the props they sell and the other blades (the todds models ones not the draganflyer ones) are almost identical so it is a good source. i am using the EPS-300C-C system they sell. it is a 5.33:1 ratio and is swinging a 10x4.5 prop drawing about 8 [email protected] volts. for the four motors, that's about 32 amps so you have to find a battery that will put out that kind of current that doesn't weight too much. if you go to batteriesamerica.com and click on battery cells, the one that works best for this application (around that same draw and weight limitations) are the cp-1300 scr cells. you you won't find a commercial battery pack that will work very well. those cells i mentioned are ultra low impedance meaning they can put out a lot of current for their capacity. they are micads listed under the fast charge cells catagory. they are only a 1.3 ah battery however (you sacrifice capacity for the low impedance) and at that amp draw you only get about 2 mins of flight time. that alone is a $40 pack (for an 8.4 volt pack) and if you go smaller you will most likely fry the batteries awful quick. you can go with lipolys but you have to get a lot of huge packs and then you get a lot of flight time but you will have to get so many it will cost you at least a hundred dollars for all the cells. i am not dictating i am just saying that unless you want to spend a bunch of money you won't get a lot, and in my opinion these are your best bet. once you figure out all that then you need to figure out what speed controllers you need. don't go too heavy, and if you go too cheap they may not have a good enough resolution to allow for an accurate control. remember these are designed to power a single motor on a plane so accuracy isn't an issue. so when you put the cheap stuff in a thing like this it really shows. if you can find some of hitecs now discontinued sp-1010 speed controls, they are 10 amp rated, very very fine control, they have both motor arming switches and bec switches. but nomatter what you do, put a fuse on them. there's a lot to this.