Geoff Gardiner Posted August 6, 2015 Share Posted August 6, 2015 Hi All. I have recently obtained a second hand Puppeteer and am in the process of converting it to an electric setup. I have been looking for a rough guide to the relationship between power increase to increasing prop size – so that I don’t have to spend a fortune on loads of different prop sizes. This is what I have: Motor – Turnigy G60 – 300kv Battery – Lipo 5Cell 4000mah 45C ESC – 80 Amp (separate bec) All up weight – 3482g (7.68lb) I initially thought I would need around 750-800W (using the 100W per 1lb rule) but I believe Mr Danny Fenton managed to fly a 9lb Puppeteer on 330W! I have tried 2 props, which gave the following readings on the wattmeter: 14x7 APC e - 215W – 11A 14x8 APC e – 300W – 15.4A Can anyone advise what to try next as I don’t want to keep buying props at £12-15 a go. I can physically go to about 17inch before I turn it into a lawn mower. I was hoping someone had produced a rough guide to % increase in power as you step up prop sizes and pitch. Any advice gratefully received. Geoff… Quote Link to comment Share on other sites More sharing options...
Gavin Mack Posted August 6, 2015 Share Posted August 6, 2015 http://www.modelflying.co.uk/forums/postings.asp?th=66615 http://www.modelflying.co.uk/forums/postings.asp?th=31610 Edited By Gavin Mack on 06/08/2015 08:51:43 Edited By Gavin Mack on 06/08/2015 09:00:23 Quote Link to comment Share on other sites More sharing options...
Reno Racer Posted August 6, 2015 Share Posted August 6, 2015 Geoff, try this, **LINK** . It will save you money in working out EP components and props Quote Link to comment Share on other sites More sharing options...
Gavin Mack Posted August 6, 2015 Share Posted August 6, 2015 Looking at my pup it has a 17" prop, doing a google search should find plenty of other electric conversions as it's a popular plane Quote Link to comment Share on other sites More sharing options...
Geoff S Posted August 6, 2015 Share Posted August 6, 2015 Sadly, I think you fundamental problem is that your motor kv is too low. The theoretical max rpm on 5S is only about 6000 rpm (300 x 18.5 = 5550) so you need bigger props to get the power you need. The 500kv version draws about 47 amps on a 13x8 (or perhaps a 14x7) which would suit your needs according to HK. Unfortunately, it's on backorder in the UK warehouse (isn't that often the case? ). Might be cheaper than buying a load of props and save this motor for a 6S battery - or use that in your Puppeteer? HK claim only a 17 amp draw on 5S with a 15x8 prop (306 watts) with a thust of 1950 grams with the G60 300kv. In fact none of the claimed figures seem to give a lot of power, even on 6s. It might be better to bite the bullet and get a different, higher kv motor than try to compensate by fitting a much bigger prop. The Puppeteer is a fairly slow flying model which really needs a propeller with a pitch at the lower, rather than than the high end of the range - 6 or 7? I would have said your 14x7 would be ideal with a suitable motor? Geoff Quote Link to comment Share on other sites More sharing options...
Trevor Crook Posted August 6, 2015 Share Posted August 6, 2015 Geoff, I would agree with the other Geoff above about trying another motor. All I would add is that you won't need 100W/lb for this type of model to achieve a respectable and realistic performance. From my experience with the (smaller and lighter) Flair SE5A, which flies well on less than 400W, I'd say 500-600 will be ample. Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted August 6, 2015 Share Posted August 6, 2015 Agree with GS, kv far too low. Did a quick calc earlier on and the best you're going to get is around 300W @ 5000 rpm (ish), which represents about 3lbs static thrust on a 14" prop. Pretty feeble even for the good old Puppeteer. Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted August 6, 2015 Author Share Posted August 6, 2015 Thanks for your replies. I am hoping not to have to change motor or batteries so I thought I would try a different prop first. I had seen a youtube clip of a pup using the same motor with 6S battery but a 14x6 prop, and it flew rather well. I had a go on eCalc but did find the figures (for the props I had already put the meter on) coming out quite a bit lower for the power estimate. Using this and my 'best guess', I have just been to my LMS and purchased a 17x8 APC e. This is giving me 430W - 22A at full chat. More importantly, it nearly rips my arm off trying to hold it back. Tomorrow's weather looks promising so I think I will try it with this setup and see what happens - fingers crossed. Geoff... P.S. Does anyone use differential on the ailerons (less down than up, i believe)? Quote Link to comment Share on other sites More sharing options...
Trevor Crook Posted August 7, 2015 Share Posted August 7, 2015 I think 430W should be fine - that prop turning slowly should be nice and efficient, with plenty of draft past the cowl. I use differential ailerons on the SE5A, also have 15% rudder coupling - I know some would say that's cheating, but I like an easy life! Let us all know how it went. Quote Link to comment Share on other sites More sharing options...
Cuban8 Posted August 7, 2015 Share Posted August 7, 2015 Geoff, what rpm are you getting with the 17x8? Fortunate that you've got enough ground clearance with the larger prop - very often not always the case. Edited By Cuban8 on 07/08/2015 13:31:53 Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted August 7, 2015 Share Posted August 7, 2015 one of our older club members(BVRMC) electrified his magnatilla successfully ...pat is his name he may come on to this thread and let you know what set up he has...probably work with your pup. ken anderson...ne...1 electric dept. Quote Link to comment Share on other sites More sharing options...
PatMc Posted August 8, 2015 Share Posted August 8, 2015 Ken, I prefer the term "one of our more senior club members". Actually the Puppeteer's a bit heavier & bulkier than the Magnatilla so I'd expect it to need a fair bit more power. FWIW my Maggie's power train is a 4s lipo, Turnigy 3548/900 (old version), 60A esc & 12x6 APC prop. The lipos originaly used were 20C rated 4000s but recently I've been using 30C rated 2650s. Numbers with the 4000 lipos are : 99oz AUW, at WOT : 31A, 460W, 8700rpm. The model previously flew powered by an original version OS40FS & a, slightly more powerful, pre-schnuerle Super Tigre 40 both driving a Graupner grey 11x6 prop. It gained about 16oz in the over-engineered conversion to electric but is actually more sprightly. I suspect that the extra inch has made a big difference to the prop's effective thrust given the size of the cowl. Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted August 8, 2015 Author Share Posted August 8, 2015 Thanks everyone for your input. Cuban8, I don't have the ability to measure rpm. It flew yesterday. It is possibly a bit underpowered but there may be a element of me not being used to the slow flying characteristics of this type of model. This is the second flight: Quote Link to comment Share on other sites More sharing options...
Geoff S Posted August 8, 2015 Share Posted August 8, 2015 That seemed to fly with sufficient authority and actually quite fast. It certainly took off very quickly which would imply that there's sufficient power. It would be interesting to know what rpm you're getting with that huge prop. How long was the flight? Your video is obviously edited so it's not clear. It rather looks as if the Puppeteer would loop easily from level flight. Did you try that? Mine flew OK with an Irvine Q40 which are known for not only being quiet and quite torquey as well but I can't remember what prop I used, possibly a 12x6 but certainly at much higher rpm than you're getting. Nice model. Geoff Quote Link to comment Share on other sites More sharing options...
Stevo Posted August 8, 2015 Share Posted August 8, 2015 Nice take off... That must be a 'scale' speed of 300mph + Possibly under powered? I think not - you've got it right on the button Geoff! Quote Link to comment Share on other sites More sharing options...
Trevor Crook Posted August 8, 2015 Share Posted August 8, 2015 Looks to have plenty of urge, Geoff. Glad you found a solution with your existing motor and cells. Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted August 9, 2015 Author Share Posted August 9, 2015 Having had a chance to think, I am wondering if I may have an issue with one of my batteries. I have 3 identical Zippy's. One is brand new and the other two are maybe a couple of years old. The older ones have only been used once before the model they were being used in 'took early retirement'. They have held charge, cells balance and show no signs of puffing. When flying my Pup, I set the timer for 7 minutes. The first (maiden) flight seemed to be more of a struggle to take off and I was having to use close to full throttle most of the time. Once landed, I checked the battery (which was quite warm) and it was showing 50% used. The other two flights, with the other batteries, seemed to have more power on tap and I was using less throttle (the video is of the second flight). The batteries had only used 20% and were not warm at all. I will keep an eye on my batteries and see what happens next time out. Quote Link to comment Share on other sites More sharing options...
Geoff S Posted August 9, 2015 Share Posted August 9, 2015 It could be that your older batteries are suffering from a high effective series resistance (esr). A typical battery can be considered as a perfect battery with a series resitance. It's current flowing through the series resistance that makes it get hot and also causes a voltage drop so there's a lower voltage supply to your motor. A reasonably good LiPo has a series resistance of around 5 milliohms or lower but that can increase as the battery ages. That won't show up with a simple check of capacity. So a good battery will drop 5 milivolts/amp (150mv for 30 amps) and disipate 900mW at 30 amps because the power is proportional to the current squared. If you know anyone with an icharger then that will tell you the esr of your battery packs. Geoff Quote Link to comment Share on other sites More sharing options...
John Emms 1 Posted December 24, 2016 Share Posted December 24, 2016 Coming a bit late into this one (a LOT late!). I owned a Magnatilla, that was very pleasant to fly, and had more than enough performance on a Merco 40. I have also test flown two Puppeteer, I am sure both had Super Tigre 60, and I would have preferred more power "to get out of trouble". I see the Magnatilla as a 4S model at around 450 to 500W, and the Puppeteer as a 6S model at around 700 to 800W. Motors of around 300kv, I would have been selecting as a part of 8S power systems... But if it works for you on 5S, that is clearly fine. Regards, John Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted May 27, 2018 Author Share Posted May 27, 2018 Still flying the pup. I have recently added a 3d printed radial engine and wooden prop. Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 28, 2018 Share Posted May 28, 2018 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
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