Merlin spit Posted June 22, 2009 Share Posted June 22, 2009 hi ive got this setup out of a foamie protech cessna(more glue and tape and hard to trim now) ,its a outrunner motor on a stick mount using a 8*4 prop it pulls 7.5a 70w on a 3s 1250 lipo with a appolo 25esc auw was 750g on the cessana but was over powered ,i was looking for somthing like a artf cub or similar (maybe a warbird)to put it in but any ideas welcome id consider myself able to fly most models so any suggestions welcome Quote Link to comment Share on other sites More sharing options...
Jonathan Lewzey Posted June 23, 2009 Share Posted June 23, 2009 Sure its not 170W? 170 would make more sense with the other components. 750g is over 1lb so that would be a lot less than 70W/lb - hardly overpowered. An alfa or flying styro warbird might fit the bill. Quote Link to comment Share on other sites More sharing options...
Merlin spit Posted June 23, 2009 Author Share Posted June 23, 2009 i just double checked it on the wattmeter with a fresh battery its pulling 98w peak at 9a about 85 watts constant ,the cessana did seem overpowered but not by much i would have thought somthing around the 750g mark would be good again Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted June 24, 2009 Share Posted June 24, 2009 hello austen-a gws corsair will fit the bill for you and your set up-get the no power system version-allready painted etc-fit gear and away on a mission................ ken anderson.............. Quote Link to comment Share on other sites More sharing options...
Jonathan Lewzey Posted June 24, 2009 Share Posted June 24, 2009 ok, the corsair or another small warbird would be fine. Just watch the AUW. I've got the GWS mustang converted to PSS which flies well so any small GWS model would be fine. Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted June 24, 2009 Share Posted June 24, 2009 here you go austen-10-15 min's with a 3cell 1000m/a lipo... ken anderson............. Quote Link to comment Share on other sites More sharing options...
Terry Whiting Posted June 24, 2009 Share Posted June 24, 2009 I'm curious to know how this figure of 100W pr lb was arrived at. I admit I'm new to electric and have found it a complete new learning curve after so many years flying IC. In the late 60's and 70's a 4-5lb model was flown on a 40 size motor,(8cc) which by todays standard would have a power rating of a 25-30 motor (6cc). , but who would think of flying 4-5lb on a 30 size engine. Today the model is more likely to be flown on a 46-52 size engine. These days there seem bo be a lust for the excess (power), has this lust also given rise to the 100W lb figure? I currently fly a 5.75 lb Hawker Tomtit on 325W. A 7.25lb T,N. Lancaster on 345W, and a 7.75lb Puppeteer cum Stutter on 450W. Now these Watt figures are only required for ROG , once airborne I'm flying between 1/2 and 3/4 throttle Quote Link to comment Share on other sites More sharing options...
Merlin spit Posted June 24, 2009 Author Share Posted June 24, 2009 thanks guys the gws series looks idea just got to pick one now ,im going to wings and wheels so hopfully il see one there ,if not ive already seen the painted nps corsair for £30 +p+p which has to be a bargain .Edited By austen rover on 24/06/2009 15:38:37 Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted June 24, 2009 Share Posted June 24, 2009 Terry, you have a fair question and I think it perhaps also illustrates why it is very difficult if not impossible, when people ask for "equivalents" to IC when they start on electric flight. There are simply too many variables ( which should be viewed as a good thing BTW ) that can be applied to leccy powertrains which are not so with IC. For example, sticking a larger fuel tank in an IC model cant change the way the motor runs, it just runs for longer - but the revs and torque etc are the same, fitting a larger prop will very likely cause the engine to labour, and not achieve its correct power band and so on. However, variations of battery voltage and prop size on an electric model will alter its flying characteristics tremendously - and this is some of the reason that trying to use a "one size fits all" approach such as "you need 100 watts per pound" is not very accurate. I have heard people say that you need at least 150 - 200 watts per pound for EDF...yet I have EDF stuff which is more than fine on 120, conversely, but there is also the belief that slower flying biplanes and the like will be OK on as little as 50 watts per pound. The truth probably lies somewhere in between, and of course what one person sees as fast, another person complains is too slow and so on. One thing I do often suggest to people when they are dabbling in the black art, is to have a variety of props, and if possible a selection of different voltage batteries, and using a wattmeter, aim for approx 75 Watts per pound for first flights of most prop models, and 100 watts for EDF. Then, after that first flight, experiment with those other components and being mindful of the maximum tolerances of the components, adjust things unitl it flies right for them. Edited By Timbo - Moderator on 24/06/2009 18:23:03 Quote Link to comment Share on other sites More sharing options...
Terry Whiting Posted June 24, 2009 Share Posted June 24, 2009 Thanks Timbo, one thing for sure I'm gathering a great collection of props which are an asset when static testing. After years of IC I have come to realize just how flexable electric power can be. Edited By Terry Whiting on 24/06/2009 21:04:11 Quote Link to comment Share on other sites More sharing options...
Merlin spit Posted June 27, 2009 Author Share Posted June 27, 2009 just an update i picked up a gws painted me 109 at wings and wheels for £25 Quote Link to comment Share on other sites More sharing options...
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