Robin Kearney Posted May 14, 2012 Share Posted May 14, 2012 Hi, I'd like to pick the brains of the collective if I may! My current project is nearing completion and thoughts are turning to to what I might build next. I've always fancied a BB Diamond Demon, which I'm thinking I could convert to electric power. Lurking somewhere around here are a couple of spare motors (a A2208-17T 1100Kv from BRC and a EMAX CF2822) and ESCs. So my question is whether either of these motors would suit? As far as batteries go I have a few 1000mah 3s lipos, but nothing smaller, it wouldnt be a deal breaker if I ended up having to buy a battery. r. Edited By Robin Kearney on 14/05/2012 22:37:06 Quote Link to comment Share on other sites More sharing options...
kc Posted May 16, 2012 Share Posted May 16, 2012 I am surprised none of the experts have given advice so far! Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted May 16, 2012 Share Posted May 16, 2012 Posted by kc on 16/05/2012 17:21:19: I am surprised none of the experts have given advice so far! I'm not, more information is definitely needed. I haven't a clue about model plane electric motors etc but iirc a diamond demon was designed around something in the range of .10 to .15 glo so anything that matches one of those is up for it, ie if my memory is correct. Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted May 16, 2012 Share Posted May 16, 2012 Having looked at the BB website, the model is designed around a 1 to 1.5 cc diesel, so basically you will need a powerset that will spin a 9 x 4 prop at between 7 to 9000 rpm. Weight will be up on a freeflight version so that needs to be considered. HTH. Edited By John Gibbs on 16/05/2012 19:57:16 Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 16, 2012 Share Posted May 16, 2012 Hardly call myself an expert, kc, just enthusiastic! However, looking at those two motors, I suspect they'll be a bit marginal - as far as I can see, they're good for up to about 90W or so. It might be worth having a read of Lee Damms Matador thread where he is electrifying the Matty, which at 48" span is about the same size as the DD. I suspect you'll be looking at an AUW of about 1 1/2lb, perhaps a bit less, particularly with 1000mAh Li-Po's. 70W/lb is a realistic minimum to give you a bit of oomph in the air with a vintage type, so that would make 105W minimum. I'd rather have about 140W to play with and use the throttle! There is some data about the Emax CF2822 here if it helps. Alternatively, I'd consider something like this KD 1130Kv motor which would probably give a bit more of a margin. The 1000mAh packs might limit your run time, whichever motor you use, however, much of the fun with a vintage is the climb and glide so that may not be an issue. Hopefully, a real expert will be along soon..... Pete Quote Link to comment Share on other sites More sharing options...
Robin Kearney Posted May 16, 2012 Author Share Posted May 16, 2012 Hi John, you are right, sorry about that I was a little light on the details. Pete, thanks for your input. I've had a good read through the Matador thread, very interesting. SteveH measured his CF822 on a 2200 3s LiPo at 165W. Which should be sufficient. Funnily enough I have three 2200 3s Lipos which I occssionally use in a Heli, so they might make a good fit. I was assuming the 1000mah at first just to keep the weight down, but maybe the 2200 is the way to go. Ideally I'd like to use what I have sitting around rather than having to buy new, if I just have to get the balsa it'll fit in my budget! I've taken the plunge and ordered the DD plan, I accidentally (oh ok, not that accidentally) put a Matador plan in the order as well just because I love the look of both, when the plans are laid out in front of me I'll make up my mind which to build Edited By Robin Kearney on 16/05/2012 22:09:59 Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 16, 2012 Share Posted May 16, 2012 Ah yes, I've now read the the thread through myself () and found a better set of specs for the CF2822 than I referred to earlier, so it certainly looks as if it will do the necessary. Pete Quote Link to comment Share on other sites More sharing options...
kc Posted May 16, 2012 Share Posted May 16, 2012 Of course the weight of an electric motor is usually a lot less than the IC motor it replaces, so for these short nose vintage models you often need a lot of nose weight. A 2200 LiPo will provide weight in a useful form, if you can fit it in. Maybe extending the nose will get weight far enough forward to produce a lighter model even though it's non vintage. Quote Link to comment Share on other sites More sharing options...
Robin Kearney Posted May 21, 2012 Author Share Posted May 21, 2012 The plans have arrived, and I have to say KC, you arn't wrong about the short nose! I need to find a bit of time to lay the motor and battery out on the plan but the thin triangular fueselage looks like it might be tricky to get the battery somewhere useful. Needs more pondering I think! I'm wondering if this is why I've not seen many (any?) electric Diamond Demons r. Quote Link to comment Share on other sites More sharing options...
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