old man emu Posted June 16, 2015 Share Posted June 16, 2015 How can I locate the article that appeared here in the News section recently which contained a video interview of an electric motor for airplanes that was powered by LiPo batteries? OME Link to comment Share on other sites More sharing options...
facthunter Posted June 17, 2015 Share Posted June 17, 2015 How do you interview an electric motor? You could end up on a charge of verbal assault and battery. Nev 1 4 1 Link to comment Share on other sites More sharing options...
old man emu Posted June 17, 2015 Author Share Posted June 17, 2015 PEDANT!!!!!! YOU ARE JUST TRYING TO SHORT CIRCUIT MY ENQUIRY!!!! ome 1 Link to comment Share on other sites More sharing options...
facthunter Posted June 17, 2015 Share Posted June 17, 2015 just curious ......... Nev Link to comment Share on other sites More sharing options...
corvairkr Posted June 17, 2015 Share Posted June 17, 2015 Is this the one http://www.recreationalflying.com/threads/now-thats-a-lipo.135799/ Jason Link to comment Share on other sites More sharing options...
pmccarthy Posted June 17, 2015 Share Posted June 17, 2015 You think that's a Lipo? THIS is a lipo........ Link to comment Share on other sites More sharing options...
old man emu Posted June 17, 2015 Author Share Posted June 17, 2015 Yep. That's the one. Thanks. I was interested in comparing the electric motor with a 4 cylinder petrol engine. Taking the Jabiru J170-D with a 2200 engine: Engine Weight (complete to fit, without exhaust system) = 62 kg Full fuel 135 l = 97 kg Useful load at full fuel = 260 kg - 97 kg = 163 kg 135 l @ 20 l/hr = 6.75 hrs Electric motor: Motor weight (motor + controller circuitry + 21 LiPo batteries): 38 kg 135 l fuel weight in batteries = 75 batteries Useful load: 260 kg + (62 - 38) = 260 + 24 = 284 kg Total number of batteries equivalent to full fuel and engine = 21 + 75 = 96 21 batteries = 1 hour's power, 96 batteries = 4.5 hrs. The big question to answer is: "How many units of horsepower are required to maintain straight and level flight at a constant speed?" In other words, if L = W, how much Thrust is needed to balance Total Drag? OME Link to comment Share on other sites More sharing options...
Old Koreelah Posted June 17, 2015 Share Posted June 17, 2015 Cricket, OME you must have a lead foot. 20lph on a 2200? Link to comment Share on other sites More sharing options...
old man emu Posted June 17, 2015 Author Share Posted June 17, 2015 Yeah. I just used that figure for ease of calculation. Quoted figure is 16 - 19 lph. When I get some moments, I am going to look at the Lift and Drag equations to see if we can calculate the relationship, Thrust = Total Drag. According to Newton, once we get the airplane in straight and level flight at constant speed, then we only need to have Thrust equal to Drag to maintain the situation. OME Link to comment Share on other sites More sharing options...
facthunter Posted June 17, 2015 Share Posted June 17, 2015 You are not in contention there, but how will you work the figures out? You can get Shaft horsepower with a torquemeter and a tacho , but that isn't thrust. Drag in a glide at cruise speed monitoring actual glide angle, but how do you eliminate the idling prop? Nev Link to comment Share on other sites More sharing options...
old man emu Posted June 17, 2015 Author Share Posted June 17, 2015 Got to give some thought to the method of calculation, but I'm flat out like a lizard drinkin' at the moment. I'll get back to the problem tonight. I might even do Pommy Phil's trick of lubricating the grey cells with some Cab Sav. OME Link to comment Share on other sites More sharing options...
bexrbetter Posted June 18, 2015 Share Posted June 18, 2015 How do you interview an electric motor? You could end up on a charge of verbal assault and battery. Nev That's shocking. Link to comment Share on other sites More sharing options...
PA. Posted June 18, 2015 Share Posted June 18, 2015 You think that's a Lipo? THIS is a lipo........ Now that's reVolting. Link to comment Share on other sites More sharing options...
Guest asmol Posted June 18, 2015 Share Posted June 18, 2015 Guys, the leaders in the electric aircraft industry, Airbus and Pipistrel are both only getting just over 1 hour in normal flight for a 2-seater. They collectively have spent millions in developing their systems with state-of-the-art custom batteries etc so why do you all fall for the claims of some backyarders that claim unbelievable performance and duration? Link to comment Share on other sites More sharing options...
Marty_d Posted June 18, 2015 Share Posted June 18, 2015 Taking the Jabiru J170-D with a 2200 engine: Engine Weight (complete to fit, without exhaust system) = 62 kg Full fuel 135 l = 97 kg Useful load at full fuel = 260 kg - 97 kg = 163 kg 135 l @ 20 l/hr = 6.75 hrs Electric motor: Motor weight (motor + controller circuitry + 21 LiPo batteries): 38 kg 135 l fuel weight in batteries = 75 batteries Useful load: 260 kg + (62 - 38) = 260 + 24 = 284 kg Total number of batteries equivalent to full fuel and engine = 21 + 75 = 96 21 batteries = 1 hour's power, 96 batteries = 4.5 hrs. You seem to have forgotten the 97kg "full fuel" battery weight in the line: Useful load: 260 kg + (62 - 38) = 260 + 24 = 284 kg Should read: 260 kg - 97 kg (extra batteries) + 24 kg (difference between 2200 motor and electric motor) = 187 kg Still means you can carry 2 largish people with full fuel rather than having to get a new wife. The big question to answer is: "How many units of horsepower are required to maintain straight and level flight at a constant speed?" In other words, if L = W, how much Thrust is needed to balance Total Drag? Answer depends on how much drag you have, ie how slippery your design is. For something like a 701, heaps. For something that looks like a powered glider, a lot less. Link to comment Share on other sites More sharing options...
ayavner Posted June 18, 2015 Share Posted June 18, 2015 That's shocking. Think I need to meditate. OHMMMMMMMMMMMMMMMMMMMMMMMMM Link to comment Share on other sites More sharing options...
Marty_d Posted June 18, 2015 Share Posted June 18, 2015 Think I need to meditate.OHMMMMMMMMMMMMMMMMMMMMMMMMM It's good to remain current. Too easy to switch off. Some people remain active, some stay neutral, but I guess we all end up in the earth. 1 1 Link to comment Share on other sites More sharing options...
Gnarly Gnu Posted June 18, 2015 Share Posted June 18, 2015 The motors are neat the batteries are garbage. Actually worse than garbage - according to Dr John Torode from Dynon general household garbage has a higher energy density than lithium ion batteries have. Personally I want a micro nuclear reactor to power mine. Link to comment Share on other sites More sharing options...
fly_tornado Posted June 18, 2015 Share Posted June 18, 2015 I am hoping Jabiru go into the micro reactor business 1 Link to comment Share on other sites More sharing options...
ayavner Posted June 18, 2015 Share Posted June 18, 2015 It's good to remain current. Too easy to switch off. Some people remain active, some stay neutral, but I guess we all end up in the earth. your capacitance for witty observations is always electrifying. Link to comment Share on other sites More sharing options...
old man emu Posted June 18, 2015 Author Share Posted June 18, 2015 Aw, c'mon you guys . I was being serious when I started this thread and you've all just been making pun of it. I'm thinking of taking my slide rule and pencil and going home. OME 1 Link to comment Share on other sites More sharing options...
ayavner Posted June 18, 2015 Share Posted June 18, 2015 ... guilty as charged? 2 Link to comment Share on other sites More sharing options...
fly_tornado Posted June 19, 2015 Share Posted June 19, 2015 have a look at the Efan, its not designed for long flights, Airbus are trying to build a trainer that can be flown from airports close to population centers, primary goal is low noise so they can operate without complaints. the batteries are tiny compared to the size of the wing. 1 1 Link to comment Share on other sites More sharing options...
Marty_d Posted June 19, 2015 Share Posted June 19, 2015 I like that. Like a miniature, quiet, A-10 Warthog. Link to comment Share on other sites More sharing options...
bexrbetter Posted June 19, 2015 Share Posted June 19, 2015 GM Nissan and their ilk make electric cars that can go for a block or two.. and Tesla does 500km... Cars can be cruised at a mere few percent of the energy needed to accelerate them to that cruise speed, aircraft are not the same and the constant need for energy absorption is far higher. Next time you drive down the freeway on a flat stretch at 100kmh, note how little you are depressing the accelerator pedal. Link to comment Share on other sites More sharing options...
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