Mark Howard 1

I don't think it makes a difference really. Swapping the Rx between models almost certainly means a complete new setup in terms of end points, servo throws, rates, stabiliser setup (where used) etc. There's certainly more changes required for a multi-channel glider over an electric 4 channel model but a complete new setup is required either way.

It would appear that as the socket on the backup unit is undamaged, the high current required to damage the battery plug must have been drawn when the battery was unplugged. The damaged pins are those connected to cell 2 only so it would seem that perhaps the battery was subjected to a short duration short circuit (i.e. something just momentarily touching the exposed pins). Although the battery is small it would still be capable of momentarily supplying somewhere between 10 and 20 amps which would vapourise or at least heat up a fine wire strand or similar across the contacts without noticeably discharging the affected cell.

Posted by Simon Chaddock on 05/12/2018 17:49:30: Rocker Just remember the poor reputation LiPo initially gained was largely due to misuse & incorrect charging. The 1C charging limit advice is there for a reason.. Most manufacturers recommend an ideal charge rate or range. Gens Ace tend to typically be 1 to 3C with a maximum of 5C, Turnigy tend to average around 4C max depending on 'C' rating. 1C is obviously safe for the vast majority of packs but you can seriously save some charging time by following the manufacturers guidelines. I typically charge at 2C for all but the oldest, lowest C rated packs.

As Martin says, the charge rate is determined by the capacity. So for a 1C charge rate, a 2200mAh (2.2 amp/hour) battery is charged at 2.2 amps. Most packs are comfortable with a 2C charge rate if your charger can supply the current. Charging to just below the maximum cell voltage (4.1 to 4.15V) each time helps with battery longevity more than a reduced charge rate. My Revolectrix Powerlab chargers suggest a 'normal' charge at 2C and an 'accurate' charge at 1C. Fast charges can be up to 5C for large high quality, high discharge (>45C) packs if the manufacturers specs say this is safe but obviously you quickly run out of available power supply amps to charge say a 5000mAh pack at 5C. I usually parallel charge my helicopter packs as I run 12S (2x6S in series) for each flight. To charge 4 x 5000mAh packs at 2C split between two chargers sucks 40 to 50Amps out of the power supply which is its maximum capacity. So, don't listen to those telling you to charge at 10A unless your packs are at least 5000mAh or you are charging several in parallel so you don't exceed say 2C for each pack.   Edited By Mark Howard 1 on 05/12/2018 17:43:59 Edited By Mark Howard 1 on 05/12/2018 17:53:02

Posted by Gordon Whitehead 1 on 04/12/2018 16:25:31: Posted by Tim Kearsley on 30/11/2018 19:54:26: There must be an argument for the moderators closing a thread when it descends into such drivel and which has no relevance to the title. Tim. bump Why? If people are contributing to the debate, enjoying it and not being rude, why close it? Anyone not wishing to participate just needs to ignore the thread. Back on topic; frankly I think the original cost question is largely irrelevant. People fly whichever they prefer or what is dictated by the areas they fly in. Cost is not really a factor in these decisions.

Although the Zippy is the heaviest pack, it is also 30mm longer so if it fits and you can achieve the desired CoG, you should be able to move the other batteries forwards to hopefully achieve the same CoG as you must have 30mm of spare space to play with. One would hope that the Zippy, being a 60C pack, should perform better than the others so it might be worth persevering with it if it fits ok. I've added markings in the battery bays of some of my planes to allow me to position different batteries correctly.

Posted by supertigrefan on 29/11/2018 16:46:34: Could this be utilised for the Rx and servos or retracts? **LINK** It only seems to output up to 2.1 A per channel so it might be a bit tight for some servos especially retracts. It might be ok for smaller models but smaller models don't really need nor have the space for it. A conventional Rx pack might be the better bet or a lipo if you're using either a regulator or high voltage servos.

No, large or small, the setup is the same. If the ESC has a BEC to power the electronics, the Rx is the first port of call for the power. The Rx then supplies the power to the servos etc. The positive and negative leads for all electronics are effectively linked together within the receiver. Some people prefer to power the electronics separately via a receiver pack as a form of redundancy/backup. If you do this, remove the red wire from the ESC/BEC cable connector so that only the throttle signal and negative are connected to the ESC to avoid the Rx pack back-feeding voltage to the ESC (some ESC's won't tolerate being back-fed). Edited By Mark Howard 1 on 29/11/2018 05:45:34

Hi Adrian, As Ben says, good IR's are relative to pack size so smaller packs have higher IR's than large ones. The calculator that DickW mentions here helps to illustrate the point. If you plug the numbers in and divide the resultant max current number by the capacity of the pack it gives you the 'C' value that the battery is capable of (i.e. the maximum recommended discharge current). So, the 10 to 20 milliohm value mentioned in the RCME article is probably correct as for a 2200 mAh pack you get a C value of between 12 and 16 C. Most manufacturer C ratings are pretty ambitious (a nice way of saying disgustingly misleading) so 12 to 16 C from a 20 C pack is to be expected although a little low. Most 20C packs seem capable of delivering around 20C whereas a most 60C packs usually manage maybe 25 - 35C if you're lucky. There are of course exceptions but these seem to be the expected ranges. My pack (5000 mAh 6S) values of 1.6 to 2.2 give C values of 23 to 27 which considering they are variously rated at 45 to 60C is not that great but is in the expected range. My small 1200 mAh packs are pretty good as they are still giving about 35C which is pretty good for a battery rated at 70C. Your numbers are indicating C values of 10 to 12 which is quite low even for a 20C 5000mAh pack which is why I'm wondering if your charger is telling you the truth. According to the Powerlab charger manual, IR can only be properly calculated during a charge cycle when charging from somewhere below 75%. Maybe its worth experimenting with your charger at various stages of the charge cycle to see if your numbers change.   Edited By Mark Howard 1 on 24/11/2018 07:09:33

I'm not sure how old or how well used your packs are but those IR figures look a bit high to me for the size of pack. My 4000 to 500mAh packs tend to have IR's around 1.6 to 2.2 milliohms (measured on Powerlab PL8 chargers). Even my tired small packs (6S 1200mAh) have IR's nearer 3 or 4 milliohms. Your figures indicate the packs are only capable of 10-12 C or 50-60Amps. I understand that most chargers only measure IR properly during a charge cycle (the figures change with charge state and temperature) so it may be worth reading up to see how best to get accurate figures. As all of yours seem very high I suspect that either the charger is not accurate or the readings are not being taken at the correct point in the charge cycle. Of course it may be that the packs are pretty tired but as all of them are high, I suspect the common denominator is the charger or measurement process.

I have only heard of 2 or 3 people using a mix of 3D printing and traditional processes. The Kraga Maripi ( https://3dprintedrcplanes.com/maripi/ ) is a 3D printed structure which is covered in film. I am just finishing the build of one of these. There's a chap on RCGroups who has built a Calmato 40 Sports ( https://www.rcgroups.com/forums/showthread.php?3102790-3D-Print-Balsa-Hybrid-Build-Calmato-40-Sports ) using a 3D printed structure covered in balsa and film. There is the Kaier Falcon (on 3DLabPrints) that has film covered wings. I'm sure there are more but these are the ones I've seen so far. Aside from printing whole planes I have found 3D printing to be incredibly useful to suppliment traditional components or construction techniques. From various jigs and mounts to other component parts like antenna mounts, battery trays, receiver mounts, cowels, hatches, wheel spats, protection plates etc. I have also printed a few wheels and tyres (tyres use flexible filaments) which have been successful too. I'm currently building a Das Liddle Stik from Aerofred on Thingiverse which is a conventional fully printed plane.

I have built and flown a number of 3D printed planes. I find the whole process fascinating but at this stage in the development, they are not without their problems. As Martian says, there are many advantages that make it worth pursuing but with the current crop of plastics available there are a number of issues which mean that 3D printed planes can be somewhat problematic. Probably the biggest issue we have is the density of the plastics available. To make structures light enough, they have to be dimensionally small and therefore structural integrity tends to suffer. The plastics available are in the region of 8 times more dense than balsa and 2 times the density of ply. So a typical structure needs to be a fraction of the size of a conventional build. Currently the models are capable of flying very well but they have to be treated with kid gloves and greased landings are mandatory if a pile of plastic shards are to be avoided. PLA plastics which are the easiest to print are very brittle. PETG is slightly more flexible and is arguably the best option currently. ABS is harder to print but is lighter and the least brittle but ideally needs additional structures to account for the additional flexibility. PLA and PETG are not very tolerant of high temperatures so leaving a plane in a hot car can cause warping issues. A few people (me included) are experimenting with mixed material builds where the structure is 3D printed and supported with carbon spars and then covered with conventional films or balsa which so far seems to work well but it means that repairs are not as simple as just printing replacement parts as required. It is a fascinating area of development and I have no doubt that at some stage in the future 3D printed planes will become much more mainstream but we are very much in the experimental stages at present. 3DLabprint, Eclipson and Kraga are worth searching out to see some of the planes currently available in the market.

You're right, there's not many to choose from these days. The main alternative seems to be Realflight 8 which is available as a disk or as a download via Steam. A seemingly less popular sim is Aerofly RC7 which is available in the same ways as Realflight. I use Phoenix, RF8 and Aerofly RC7 for planes (AccuRC for helicopters) and like them all. Aerofly has the best graphics, followed by RF with Phoenix being not quite as good. I think that Phoenix has the best flight physics (it can simulate tip stalls and snap spins better than the others) but RF8 and Aerofly are not far behind. Realflight benefits from a fairly active user community generating user models that are available from the Knife-edge swap pages - some of them are better than the supplied planes, some are not. Realflight also has a Horizon Hobbies add on package that includes a number of the current HH planes (including their SAFE system where applicable) if that floats your boat. There are a few other cheapie/freebie sims around but I'm not sure they are worth the effort unless your budget will not stretch to the above mentioned.

My first buddy box session with an instructor was done with a light weight foamy I had taken to the club. It was quite windy. My second session later that day was on a IC powered balsa WOT 4. I loved the stability and weight of the WOT 4 in the wind but learned a lot more with the foamy. I often fly a foamy on windy days just for the fun. Flying backwards in a head wind is a huge grin and the relative cost and bendyness of a foamy makes it a relatively low risk pastime. Foam planes are relatively cheap, relatively expendable and are responsible for bringing many people into the hobby and so should be encouraged IMO. I do agree though; an 'A test' taken on a foamy probably doesn't fully qualify you to fly a large heavy plane safely as their flying characteristics are so different. Maybe there needs to be a phased test scheme like full sized pilot training with each stage allowing you to fly different categories of aircraft (maybe based on weight) to cater for the diversity we have in the modern flying scene - I wouldn't want to administer it though.

I use auto-trim on the Horus too for the first rough trim on a maiden, it makes the process much easier. I also find that swapping the trim switches makes life so much easier too. With swapped trims the left hand stick switches control the right hand stick trims and vice versa. If you are flying mode 2 the elevator trim is done using the throttle trim switch and the aileron trim is done with the rudder switch. You can set the throttle and then fly on aileron/elevator only whilst the left hand is trimming the right stick. It's easy to do on Frsky Tx's and I think the Jeti's too but not sure about other transmitters. It's a major help on transmitters where the trim switches are small and not so easy to find by feel alone (like the Jeti).