David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 Guessing this no good? Look at this on eBay http://www.ebay.co.uk/itm/112445274581 Quote Link to comment Share on other sites More sharing options...
PatMc Posted July 10, 2017 Share Posted July 10, 2017 Posted by David Wainwright on 10/07/2017 14:58:53: Guessing this no good? Look at this on eBay http://www.ebay.co.uk/itm/112445274581 Good guess! Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 So how about redneck remedies like converting an alternator or using washing machine motor and inverter? Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted July 10, 2017 Share Posted July 10, 2017 Posted by David Wainwright on 10/07/2017 13:42:56: Ok, thanks for replies so far. Just to clarify, this was never supposed to be a serious bit of kit designed to fly 90kg. For a start, the wing is what flies it. Am just after a motor to power the prop. As an incentive and seeing as they have just delivered two props by mistake, anyone who can come up with a viable option which falls within parameters, and they pay postage, they can have a free, 30x10" carbon prop as thanks. Remember, I'm not building a rocket. Yes, but you've said you want 10,000 rpm................... a DLE 120cc 12 HP at 7,500 rpm has a largest recommended prop size of 28 x 10, so for a 30 x 10 you'd need something say equivalent to a 150cc engine, like this, you'll need more volts than 12v though Washing machine motor would be an option if you run it from the mains as they are synchronous AC motors. Edited By Frank Skilbeck on 10/07/2017 15:59:34 Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 10, 2017 Share Posted July 10, 2017 David you mentioned in one of your posts you wanted enough power to move 90kg and even though the wings do the flying the model is still 90kg and has certain restrictions on it. As the other guys have already mentioned you wont get a prop that big to 10k rpm. The prop tips will be supersonic and the propeller will disintegrate. You also need almost 60hp to turn a prop that fast and that is not really very practical. As you have not provided any details of what your project is, its dimensions and its performance requirement it is more or less impossible to offer advice. Your apparent lack of understanding of the basic principals is also a concern as the sort of power we are talking about is non trivial and quite dangerous if you lack the experience to operate a model of this type Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 That's a really helpful post. Thanks. Looks like battery packs gonna need reviewing but that's clearly a substantial motor. 10kw kits are over four grand so this looks feasible if can keep price batteries and controller down. Is 150cc equiv to petrol output then? Thanks again for your time, input and taking me seriously. Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 And I'm here for info, not to be judged thanks. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted July 10, 2017 Share Posted July 10, 2017 Yes, the 150cc is equivalent to a petrol 150cc, running the motor, Turnigy RotoMax 150cc through E Calc with a 30 x 10 prop gives the following on a 12s battery (10,000 mah 45c) rpm - 6,000 thrust - 26 kg volts - 44v amps - 194 A around about 8.5 kw (90% eff), motor is rated upto 9.8kw Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 Thank you. Very useful. Guessing lithium power packs and hefty potentiometer needed. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 10, 2017 Share Posted July 10, 2017 I think we need some clarification / confirmation. As I understand the OP and subsequent info, this project is for a backpack type power unit for a man carrying wing, so large model regulations don't come into it. There are many factors to take into account and the speed range is very important. Static thrust (your angle grinder experiment) means very little as the relative airflow will change dramatically with airspeed. Power in (as I discovered recently) does not necessarily relate to power out as electric motors have different efficiencies at different loadings (rpm) and this can easily vary between something in the order of 40% and 90% To get a realistic estimate, factors such as wing loading, stall speed and maximum speed will need to be taken into account as well as safe/efficient propeller rpm. Quote Link to comment Share on other sites More sharing options...
Dickw Posted July 10, 2017 Share Posted July 10, 2017 Posted by David Wainwright on 10/07/2017 16:17:46: Thank you. Very useful. Guessing lithium power packs and hefty potentiometer needed. That motor won't run on DC, and a potentiometer won't help you. You will need a speed controller capable of at least 44v and 200amps going by Frank's data. Something like this:- https://www.electricwingman.com/jeti-spin-300-opto-controller.aspx Dick Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 Blimey. That costs more than the motor! Wasn't expecting that! Clearly a couple of lithium car batteries not gonna do either.Thanks for info. Quote Link to comment Share on other sites More sharing options...
Slickriff Posted July 10, 2017 Share Posted July 10, 2017 Unfortunately cost will be high. The potentiometer would have to be able to take the power dumped away from the motor when it it turned down. That means it becomes a several KW heater. It is for that reason you have no choice but to use a speed controller, and at high power they are expensive. In the model world anything more than a few kW would result in a petrol engine being used based on cost alone for all bar the most determined. At high powers the motor ends up the cheap bit. Even the batteries become VERY expensive, and that is for flight times of under 10 minutes, which I am guessing won't be enough for a paraglider. 4kW at 12V is 333A. That means a 33Ah battery (33000mAh) would only last 6 minutes. Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 https://hobbyking.com/en_us/turnigy-rotomax-100cc-size-brushless-outrunner-motor.htmlThis says it will power a 27x12 prop so 30x10 ok? Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted July 10, 2017 Share Posted July 10, 2017 The Blackhawk electric para glider uses a 10kW motor driving a 51in prop here. I think you need a bigger prop, more volts, less RPM and deep pockets! Good luck David. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted July 10, 2017 Share Posted July 10, 2017 Posted by David Wainwright on 10/07/2017 17:58:24: https://hobbyking.com/en_us/turnigy-rotomax-100cc-size-brushless-outrunner-motor.html This says it will power a 27x12 prop so 30x10 ok? Yes, the beauty of an electric motor is it's flexibility, but while this would turn a 30 x 10 it would be at less rpm than 150cc version, and power is roughly proportional to the rpm squared, i.e. if it turns 2 twice as fast it needs 4 times the power, so you'd have to drop the volts and that would drop the amps, and the thrust. Quote Link to comment Share on other sites More sharing options...
Slickriff Posted July 10, 2017 Share Posted July 10, 2017 I assume you realise that 12s is not 12V. It is 12 lipo cells at 3.7V each. 12x3.7=44.4VSo this motor would spin it, but at 44V to match 100cc engine.12V would not be even close. Quote Link to comment Share on other sites More sharing options...
Slickriff Posted July 10, 2017 Share Posted July 10, 2017 So at 44V you would need 4 batteries in series. It would pull 180A, so 4 lithium car batteries of say 54Ah each would run the motor flat out for 18 minutes. (discharging to a point that would not be advisable).....and I am guessing be a bit heavy and bulky into the bargain. Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 Yes, this has been covered and refer to first post re what needed. Seen 80cc motor, batteries and controller for under 500 that will produce what is needed. Didn't want a rocket.Thrust produced by above will be more than adequate. Thanks to those who chose to share knowledge rather than be blind to fact knowledge is only power when shared. Quote Link to comment Share on other sites More sharing options...
Paul Marsh Posted July 10, 2017 Share Posted July 10, 2017 I was wondering if you intend to fly your rig, I hope you know what you are doing. Also any legislation you will need, You should join the relevant club even before you spend any money. I reckon you just can't launch yourself into the air without training or licence and what I see here is a little risky - strapping a 80cc plus motor, with a 30 inch carbon prop doing 10000rpm with 44v of lithium batteries on your back, with no idea what you are doing. EEK! Sorry, but it looks like that - getting chopped up in the air with a 30inch prop then blown up when the batteries catch fire... see here: https://www.bhpa.co.uk Edited By Paul Marsh on 10/07/2017 20:36:55 Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 Condescending? You don't know what it means!Edited By David Wainwright on 10/07/2017 20:54:05 Quote Link to comment Share on other sites More sharing options...
David Wainwright Posted July 10, 2017 Author Share Posted July 10, 2017 Now see here,If you had bothered reading original post you will see it was a request for info and background as to neivity. Not sure which part of your answer addresses this. For your info, I trained and qualified in Derbyshire several years ago. During a session teaching, I saw folk steering their wings using cordless leaf blowers. I was never after a five grand rig, just a compact and light alternative for extra thrust.If you would care for a lesson get in touch!As for rpm, I'll be happy with max 5000 after doing calculations. Thanks for the unwanted concern however. X Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted July 10, 2017 Share Posted July 10, 2017 Right that's enough. BEB Quote Link to comment Share on other sites More sharing options...
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