Peter Beeney

   I put mine in the petrol cans. After all, it does say, ' place in a metal container......'

    Eric,    Thanks for your answer.  At least you know the cause of the crash was straightforward, even if the reason was a bit of a mystery.  I’ve seen this occur, too, admittedly not very often, and I found that yanking the lead out of the master effected a cure. Theory says that if anything goes wrong, the master tx takes control, no matter what, and that does happen, usually, but I wondered if the tx’s could get crossed up in some way. In your case, as you say, it could well be the battery, but I would be gently surprised if it was. I’ve generally found, that once it’s flat, if it recovers it very quickly fails again. May I recommend you do a bit battery inspection. Oddly enough, I’ve just posted about batteries in the ‘Saito cutting out. Help please’ thread by Tim Campling, and also ‘Common sense regarding ALL batteries’ by Myron Beaumont.     I reckon you did the right thing, model wise. If the Wot Trainer is only half the model of Chris’s Uno Wot, then it’s still a cracker!  Unfortunately we don’t have any in our club, I shall recommend it to the next person that wants to learn to be a total masochist. I’m sure your Instructor gives it the occasional workout, and with that lively lump energetically cranking it’s curly bits, I imagine whole package is given a plus vote.     You Have Control!    All The Best.             PB

    I’m afraid that there is a rather different rule for consumer items as opposed to industrial items. The consumer industry has a vested interest in just selling batteries.  Does it suit them to give as little information away as they can get away with? I think it does! It would need a concentrated effort, perhaps by all consumers acting in concert, to change this, and that might not happen.     Regarding a battery’s age related to it’s quality, for lead acid and nickel this may not be a big issue. Nickel cells can last up to 20 years, the best I’ve seen is 27 years, and I had some Saft 4Ah D size nicads for over 15 years, I’d bought them as scrap, from an electronics maintenance man, so they could have been more than 5 years old then. Lead acid can live longer than 20 + years, I know of one set of cells that is over 30 years old, and still going strong, although I think this is exceptional.    It all depends, to some extent anyway, on the amount of TLC!     There has been some evidence to suggest that lithium cells are subject to ageing, irrespective as to whether they are used, or not, at least up to now, but that may be changing. The latest generation of the more up-market lithium polymer power supplies, i. e. expensive laptops, is suggesting a 4 - 5 year life cycle. We can but hope that this will eventually filter down to the model flying fields!       My personal drum is the one that beats out the message, please test your battery pack, from new, and also on a regular basis. I’m generally not in agreement with throwing good packs way, for a whole variety of reasons; one, of course, is the fact you could swap a perfectly good pack for dodgy one, certainly I’ve seen more than some evidence that brand new packs can be faulty.     I’d imagine that in the main, the turnover of batteries is fairly brisk, so that by and large they do not have a long ‘on the shelf’ life. But there are exceptions to every rule, and I’m sure occasionally one of these must crop up.     I’ve very recently purchased a pack of 4 2900mAh AA Ni-MH, with the intention of testing them for capacity etc. but mostly to prove, or perhaps disprove, the tendency to fail under heavy loads theory. I’ve only got as far as far as discharging to zero, so that I can start off with a flat battery. These were half flat, so assuming that they were fully charged to start with, then I think they could be up to a year old. I have a feeling that these cells will acquit themselves with flying colours. I’ve also got a pack of 1100mAh triple A, from the same stable, and also to be given the same treatment.     I’m hoping to get a bit of a handle on this apparently slightly conflicting argument.    PB  

    Just to clarify, is the Wot 4 one model, a high wing sports plane, and then is there the Uno Wot, Chris Foss’s Trainer. Eric says that his was a Ripmax Wot trainer,  I think this a modified or ‘made under licence’ ARTF version of the Uno Wot, probably in China. Then, if so, I’d be tempted to say that going back to a standard trainer might be, in some ways, a slightly retrograde step. The Uno Wot, Chris’s original, although regarded as a trainer, was probably only limited by the pilots ability, as they say.                Can we ask, Eric, and with the greatest respect, of course, how did you crash? If you were fooling around, then perhaps you don’t need a trainer anyway. If it was too hot to handle, would a consultation with your instructor be a good idea? If you are going it alone, a big glue pot, and a equally large sack-full of determination is a good start. Whatever model. When I remember my first lone hand 10 second attempts, off the slope, shares in Balsa Cement and Tissue Paste must have gone through the roof!     It sounds to me as though you might be well into it, so perhaps a practise model, a Seagull 40, as a first low-winger maybe, while you look around and see what you really want to fly. An Irvine 53 will give that a nice sparkle!!     This is all personal choice really, but I can only believe that if you’ve been poling a Wot Trainer around with an Irvine 53 up front with confidence, then you can only progress forwards.         Good Luck and Happy Landings.           PB    

    Tim,    I’m very glad you’ve solved it with out doing any damage. I have to say, because of the way the fault showed itself, it was not the top priority in my list of suspects. But, it’s always amazed me how these little coincidences often get together. However, and with all due respect to you, it certainly does bear out, in a fairly unambiguous way, the importance of checking the power supplies.     I’ve been repeating myself here for years.     Have you considered an on-board monitor, such as VoltSpy? I’ve witnessed at least two cases where these have saved a nice model from certain death. Oddly enough, the very tell-tale symptoms were spotted by other eagle eyed modellers just before the pilot took of on what might very have well been the model’s last flight. If you’ve not used one before, I think you soon get into the habit of checking it, you very quickly relate the flying time to the number of glowing leds; and then any abnormality shows itself in an instant. Well worth a try!     Your dodgy cell would deliver current satisfactorily until it reached the end of it’s reduced capacity, then, even if only on a fairly light load, it would totally collapse in a few moments, by at least 1.25V, thus reducing the battery voltage by this amount. On it’s own, this might not necessarily even so cause the battery voltage to drop to 3V, thus activating the fail-safe, but if this was happening after a short time into a flight it’s possible the pack was a bit iffy anyway. Maybe it’d been so for a long time, even perhaps from new. It’s happened before.     As this engine problem thread has now become very much battery orientated, right on topic now, I reckon, perhaps I can say that I’ve noticed recently some comments about high capacity Ni-MH cells being unable to deliver high currents. So I’m just purchasing some 2900mAh AA cells, and some 1100mAh AAA’s, with a view to giving them a good hammering, and a bit of a kicking, to boot, and then I’ll perhaps find out exactly what does go on with these puzzling little power supplies.     All Good Luck for future flying, and you have checked out that new battery you’ve just installed in your model, haven’t you……….        Best Regards.       PB   

    Steve,   With the greatest respect, I’m looking at this from a slightly different angle. I would be inclined to think that from extending the length of the wires from the ESC to the motor point of view, the volt drop across the length is the main consideration. If you used a conductor with a smaller cross sectional area than that of the existing motor wires then the current carrying capacity could well become an issue perhaps; however, if we increased the length, and thus the resistance of the circuit, using the same size conductor, if only a very short amount, less current would flow. A proportionally small amount less. Everything else remaining equal, of course. Volt drop will apply to the circuit, and have exactly the same effect, whether the current is continuous, or in short bursts.     I certainly agree with you on the wire size though, certainly as at least the same size as the existing motor supply wires, and in fact bigger if possible, particularly if it’s a longish extension.     I’ve seen the odd statement, a bit vague perhaps, but it seems the competition men sometimes tend to connect the battery on to the ESC, and then the ESC on to the motor. Is this an effort to eliminate the volt drop across the wires, perhaps?     Hope this all makes sense!             PB   

    Ian,     Sorry to read of your  difficulties with respect to joining a club, this must be extremely frustrating. If you try to go it alone, see if you can find some help, otherwise repairing the model might be the only order of the day, at least for a while.     I’m not entirely familiar with the JP Micro Battery Checker, but, ‘keeping an eye on it’ is the operative word, at least to start with.     Thanks for the charger details. I did slightly anticipate this. You’ve most likely sorted the charging procedures out ok, so this might help as verification. I’ve not had any personal dealings with these particular charging units, as yet. The rx half is a fast charger, it will charge the rx pack up, from flat, in around two +? hours.     The tx. I’m assuming this is also a 1200mAh battery, I would be extremely surprised if it were not. This is a slow charge, probably because Futaba still retain the protection diode in the tx, and this makes it difficult for the charger to read the battery voltage.      Establish the charging time like this -       1200mAh is the C, or capacity, it can deliver 1200 milli-amperes for one hour. Or, conversely, 1 milli-amp for 1200 hours.     The charger can deliver a constant current of 120mA. If we divide the battery capacity by the charge current we can see this is equal to 10, so we can say that we are charging at the 10 hour rate, or in aeromodelling speak, at C/10. Or, if you like, 0.1 times C. The battery will be charged, from flat, in 10 hours. But, nothing’s perfect, there will be losses, so to compensate for this we need to throw in a bit extra, this is generally 40 - 60 percent. Taking a mean line on this, lets call it 50%. So we can now deduce that we need to charge it for 15 hours. This is a standard charge.     Now you can apply this reasoning to the rx, but the peak detect automatically takes care of all the extra charging time.     My humble apologies if this is all OTT, if it is, please ignore it.     I’m sure the tx has some sort of voltage indicator, and it might also have a low volt alarm, so you are protected to some degree from a flat battery. And when you charge it, it will seldom be completely flat. So sometimes you may well be charging over the top; however, this is ok, at least for reasonably short periods of time.  A 24 hour period, or less, say.     Regarding the charger, I’m not much help here I’m afraid, my own lump is very old, but has been updated to the latest spec. It’s long out of production now, the replacement might be out this year. When I look in the mags, there seems to be a multifarious amount of chargers, batteries, and all the other paraphernalia, it makes me a bit nervous. I’ve repaired a few, oddly most ‘electrical’ faults seem to be mechanical problems, dodgy wires etc. I’m also occasionally asked to explain some obscure angle of a charger’s idiosyncrasy, but beyond that I take little notice. I think they tend to be too technical at times.     There must be many forumites that have found quality items, a few inquiries will soon yield a result, I’m sure.     If my guess about the diode in tx is correct, then I’m afraid that may in some way defeat your anticipation of fast charging the battery with a different charger. There are some options, though, you could remove the pack each time, which is a bit of a bind, and could ultimately cause you headaches, or you could remove/strap out the diode, something that I wouldn’t do, for myself at least. And you wouldn’t want to invalidate the warrantee anyway!     But this may all be rubbish, there may not be a diode!     Just for interest, my own charger has got a provision for charging via a diode, but it has got a hefty microprocessor which very carefully monitors the input voltage to the tx. It also is limited to a max 1.2A current, which you’ve already calculated is the one hour rate for your tx. 1200 milli-amperes is just the aeromodelling industry’s sexed-up way of saying 1.2 amperes.          Every success, and please don’t be afraid to ask any questions at all.        PB                           

    Thank you for the comments.           Ian,   The way I would consider it would be something  like this:  Stay with what you’ve got for the moment, don’t complicate the picture too much. One thing to consider, if you’ve joined a club, is to find a nice friendly lad that has a suitable charger that can discharge your pack to make sure that is about the capacity that it says it is. In other words, that it doesn’t have a problem to start with. I think that if you are able to do this, it is important. Being Futaba supplied, this is probably most unlikely to be an issue, but you never know. Make a note of this value, and the date, for reference to any future checks. Check your batteries regularly, say annually, and most will last for many years. As I’ve said before, I’ve never really seen the need to change them until they start to fall over.     A word of reassurance, to go with the others. 1200mAh will surely give you dawn to dusk flying. I’ve been there, a few times! On less!     Another little point of safety is that of a battery state indicator. Such as VoltSpy, or something similar. This plugs into the rx, it’s just a type of voltmeter with a full-scale deflection of about one volt; the voltage indicated by a series of leds (light emitting diodes). A four cell nickel pack will be about fully charged at 5.4V, down to a lowest useful voltage of about 4.4V. The number of leds varies, but if there are say, 10, then each one going out represents a fall of 100 milli-volts. Usually you can wait until you are going well past the centre before you even think of stopping. Certainly I know for dead certain sure these have saved at least two models, not from flying over time, but from duff batteries. So well worth the tenner purchase price. These can be set to 4.8 or 6V; and there is a version now with two DIP switches, 4 settings, these plus 7.2 and 8.4V. They may be suitable for 2 cell Li Po packs.   Point to remember -  faulty batteries can pop up anywhere!     One more related point, always lock the battery plug to the switch harness socket. I tie mine with a piece of string, only because I’ve plenty of lacing twine, relics from work. There are a number of stories concerning plugs and sockets coming apart, and you don’t need me to tell you what happens next.     If I can ask one more question, what is the rated rx output on the charger label? And also what does the instruction book exactly say about charging the rx pack? I’m only asking from a point of interest.     Now you really need to get on and enjoy the flying bit! That’s the best! But I can understand your desire to get the ground support right, then that makes life far simpler.     This is the sort of advice that I might give to any new recruits at the field, however many people also have their own way of doing things, so, as always, this is only my opinion, definitely not a set in stone wad of instructions.         Good Luck.                            PB   Edited By Peter Beeney on 29/01/2010 23:04:51

    Ian,           To make an effort to try and and your question, I need to maybe ask some questions myself, and to perhaps make some suppositions, at least to begin with.     Firstly, when you say ‘back-up’ battery, I’m assuming you just mean a spare, or perhaps replacement battery?     Also, what are your charging arrangements, do you have just the standard charger that came with the 6EX, or perhaps another type? Such as a fast charger?     The simple answer is that the 2200mAh battery would be a replacement for the 1200mAh, but with some slight complications. I think you need motive, or perhaps a different application, for doing this, and just extending the amount of capacity might not be entirely necessary. I’m not entirely sure that you would see any great benefits.     If you are using the 1200mAh in a standard 4/5 servo sports type model, then I’d have thought that this would give you adequate capacity, i. e. flying time. I’ve never been convinced that the flying loads on the control surfaces are that great anyway, all the anecdotal evidence seems to point to this. However, I’ve only ever taken a general appraisement of this, some proper documented testing might be the next trick to play. Given some good flying weather, when I can get some suitable lengthy flying sessions in!     I think there are more important aspects for your power supply that need considering first.     If you wish to dive in a bit deeper, come back with some info on your charging system, plus why you think you might need to increase capacity. We will consider the pros and cons. Also, I’m guessing again, but from your previous post about the flight box, are you just starting out as a model flyer?              Hope this is of interest.                     PB

    BB,   You are on the right track, regarding gel cells, although perhaps they are not that new. Known generally as Sealed Lead Acid, (SLA), also Valve Regulated Lead Acid, (VRLA), there are two main types. The gel cell, in which sulphuric acid is mixed with ground-up silica, to form a gel, and the Absorptive Glass Micro-fibre, (AGM), a mat which soaks up the sulphuric acid. They are designed so that they don’t generate gas, but there is a pressure release valve if there should be a build up, which, as I remember, blows at around 4lbsqin. These are claimed to be capable of being installed in any orientation, but when this was tried, albeit a long time ago, this was definitely a ‘negative’ exercise. These cells are considered benign, i. e. they don’t release any gases at all, thus they are able to be installed in the same cabinets as the electronic equipment they are driving.       Gel cells are like all the others, the quality varying from the almost immortal through to downright rubbish. Some SLA’s have failed catastrophically, within a very short time frame, even when treated with the tenderest of loving care.     An example of the better quality. Gates, an American company, (nothing to do with computers!) made many types, amongst them a 100Ah SLA. This was a king size version of the standard 12V, 7Ah type used by many modellers. I acquired one as a Maintenance Exchange, (ME), it had already done it’s allocated service time, and I installed it on my Peugeot 205 Van, with a 2 litre diesel engine, when the original battery failed. I had to pack the battery compartment out with large pieces of polystyrene foam, it was certainly far smaller, and significantly lighter, than any car battery; and I also had to make connecting links because it had threaded terminal posts. This never failed to start the van, ever, in the further five years that I owned it, and was still going strong when I sold it. This was circa. 1980’s, and since retiring rather sadly I’ve never been able to source these. It was an industrial battery, made to an aviation spec., I believe, there was no information legend on the cell at all. But it certainly can be done when someone really tries!        And all these particular types were exactly the same quality!     As an off-thread aside, we had a safety video, showing the result of placing a full dead short across a number of SLA’s, in series and parallel configuration.  50V and up to 2000Ah. The result was impressive, to say the least.     Hope this is of interest.                   PBEdited By Peter Beeney on 26/01/2010 21:14:44

    Whilst not wishing to get at all involved in the pros and cons of the main thread, and with respect to James40, what I would be a little bit interested in is the actual fault on the tx. The blown internal fuse.     This might be the wrong place to discuss this, apologies for that, but perhaps I can at least raise the question here. I first saw this, on a JR 35MHz tx, some three years ago, when an inquisitive beginner removed the battery from his tx, just to have a look, replaced it, and then nothing worked. He suggested we have a look inside, and there was the blown fuse. At the time, I was surprised, to say the least. He returned it to McGregor, and they replaced it free of charge; but with no explanation. Which may be understandable, given the circumstances.     Subsequently, I’ve read the odd report about Spektrum tx’s and blown fuses. So now can I assume that Spektrum, in conjunction with JR, have a fuse in the input line to the tx electronics? Obviously, they have a reason for this, but I have taken the back off a number of other makes of tx’s, over the years, and I’ve never seen this feature before. In fact, I’ve always understood that the general consensus of opinion said that this was to be avoided, on safety grounds.     So, on these same safety grounds, can I ask if there are any records of this fuse blowing on a transmitter in use, i.e. before or during flight?     This line of thought may well be inconsequential, in which case it can be ignored, or perhaps otherwise may be worth moving to a specific thread.       PB

    Ralph,         Speaking from the benefit of spending far too many years slaving over a hot buddy box, there are one or two facts that I’ve learnt. This tome applies mainly to 35 stuff, 2.4 is easier in some respects.     Very importantly, and firstly, you need an infinite amount of patience. Plus you need to become an expert in all things aeromodelling, aerodynamics, principles of flight,  engines, batteries, radios, models; plus an unshakeable knowledge of the BMFA handbook. Latterly, a complete understanding of electric flight is becoming very necessary.      We start by teaching club etiquette, frequency control and engine/pit safety the most important. Whenever possible, I like to use my own kit, at least at the very beginning, then there is only one unknown quantity, the beginner him/herself. Slightly controversially, when simulators started to appear, I always suggested, that if possible, the pupil ignored these and learnt to fly the proper way; particularly youngsters. You only ever learn to fly once! Enjoy it! It’s possibly the most memorial time in anyone’s time spent model flying. But I’m sure it doesn’t always feel like that. From the instructor’s point of view there is nothing quite like the feeling of the time when you pull the plug, hand over the tx and say, ‘Ok sunshine, now show me how to do a proper circuit and landing!’ I guess this must be the same in many professions.     Again, slightly askew from conventional wisdom, I’ve always gone for full control throws. No rate switches or anything else. As simple as possible. I also like to get into things like circuits and landing approaches as soon as possible. Good discipline. But, you do have to pay full full regard to each individual’s limitations, of course. I can certainly identify with Ultymate’s ‘No two students are the same‘ observation.  From choice, I would always use a standard 4 channel trainer, in my experience anyway, that is the fastest way to go. I think they are brilliant. But occasionally, some newcomers have different ideas.      You also learn lots of useful rubbish along the way. Two little nuggets that I would uphold, associated with 35MHz, very early on. Always personally check the student’s Xtal, before they switch on, irrespective of what they tell you, and also always make sure the Xtal is removed from the buddy tx.     Little teach-in’s are useful, take an old engine to pieces and get the students to tell you how it works. Explain the fundamentals of how the tx transmits, and how a servo works. The only trouble with this sort of stuff, nobody ever wants to go home. There is always someone ready to ask, “ Can we have another go, please?”     The fact you’ve asked for opinion/advice I would applaud. It also sounds as though you are already working out a system, from both yours and the beginners point of view. Ten out of ten there, too.     One final tip. The first thing any of my students have to do, as soon as they get any where near starting the engine, is to take the spinner cone off, and tighten the prop nut more securely!    Plus one more. I’ve found that sometimes treating youngsters like adults, and (some) adults like youngsters can pay dividends.     I’m sometimes asked what I get out of instructing, and I think it might only be slightly tongue-in-cheek when I say that I often think the beginners teach me more than I teach them!     Very Good Luck with it all!                     PB 

    Reading Mal’s and Erfolg’s posts about the model diesel fuel and ether respectively brought back a few memories. I think I started using diesel fuel as a primer from the time of my first glow engine, a Veco 19. But even before that, my brother and I, as schoolboys, had tried to buy ether, for home brew, from various chemist’s, but we were never successful.     I did have one engine, an elderly Moki 60, that, in cold weather, toward freezing, would not start. It was perhaps not the very most powerful of 60’s, but it was totally and utterly reliable. Once running, that is! Eventually, I discovered that warming it up with my Primus gas torch was the answer. This always instantly worked. Then we perfected the ‘hot refuel‘ technique. Engine ticking over, take the stopper out out of the tank filler, and before the engine could stop from lack of fuel pressure, filler line on; I’ve always used a home made squeezy bottle, that never fails, either, and so then refill the tank. This was slightly tricky, too much pressure, trying to go too fast, resulted in the engine flooding, and stopping. This was all a gimmick, of course, probably not at all really necessary. But all these shenanigans were always a source of great merriment at the club field, there was always the inevitable wag with some wisecrack! Great fun!     I found the diesel primer not entirely infallible, but the little system I’ve used for years must be in general use all over, I guess. If you can get at the intake, and you can on most models, two strokes anyway, open the throttle; a squirt of fuel in, that’s standard glow fuel, swing the prop to draw it in, shut the throttle. A couple more swings by hand, a short burst of starter, glow clip on, starter again, and it’s running.                    This was working for me this morning……….               PB

   Simon,             Apologies, a crossover posting by me, I fear!

    Phil,         Perhaps I can add some of my confusion to your excellent synopsis. As you said, ESCs are not perfect switches, because of the switching periods. One of the judgements of the quality, and thus in some measure the expense, of a MOSFET is the value of it’s forward, or ON, resistance. Or rather, the lack of it. The lower, the better; but, consequently, a proportional higher cost. So I’m a bit suspicious that the cheaper brands of ESCs do not always use the most expensive, and thus lower resistance, FETs. Thus the ON resistance might have a significant part to play when on full throttle, adding to the heat generation. This could be another good example of how doubling the resistance increases the power dissipated fourfold. Making your little formula earn it’s keep, let’s say, hypothetically, the resistance is 0.1 Ohm. The current 40A. Then, 40 × 0.1 × 0.1 = 40 × 0.01 = 0.4W. Doubling the resistance to 0.2 Ohm, then 40 × 0.2 × 0.2 = 40 × 0.04  = 1.6W. A fourfold power increase. I think this might account, in some small part, the reason why I seem to see probably too many cases of obvious overheating. In one or two cases, very spectacular, the ESC exploding in a shower of sparks, nothing left!     Going right back to the top of the thread, Simon’s efficiency question, this might be a thoughtful discussion. I’m not always convinced that we actually pay enough attention to the propeller/motor/battery combinations for maximum efficiency, and thus maximum performance. There might be a trade off here. Again, a dynamometer might be a useful tool.     Some experiments with the amount of watts used might be a start.     PB         

    Ian,   A slight modification then. If you use the change over switch, put the in-line fuse in between the flight box socket and the switch. If you provide it on the battery it will still be in circuit when the battery is connected to the power panel and the starter etc. This may/will cause you problems. The starter particularly sometimes needs a lot of power, this may be more than the rating of the fuse. The reason for having a dedicated pair for the charging lead, and the fuse close to the terminal is so that the maximum length of wiring is fused.     Just a thought.                PB  

    Ian,     Excellent!  I would be inclined to consider the on/off switch in the charge lead a mite superfluous, it’s just one more thing to remember. The time when you forget it will be just before one bright, warm, sunny Sunday morning…   … and as a result you’ve got a flat starter battery…   But, that is purely a personal choice.  You will now be able to charge up with impunity! These things are not inherently dangerous, think how many small, and big, chargers there are in use at any one time..    All quietly doing their thing, without any attention whatsoever.     Good Luck.       PB      

    Ian,     Very briefly, I’ve just caught up with the thread. Please don’t fit any other fuses other than in the charge lead. This could cause you more hassle than it’s worth. And again, with respect to the other posters and Myron don’t be at all concerned about any gas build up in the flight box. This doesn’t happen. If you wish, I can give you a better, but longer, explanation.     As an aside, with regard to the car fire, I think there is quite a lot of concern about the safety aspects of modern automotive electric's. Ever greater use, think of all the devices there can be, but not enough attention given to the detail, such as the fuse in our flight box charge lead. Cost, I suspect, might also play a part here.     Again, this may, or perhaps, maybe not, be of some use.      PB 

    Ian,         With the greatest respect to Tony and flytilbroke, above, may I offer a slightly alternative view?      One way of ensuring at at least a degree of safety in charging your 12V battery is to have a dedicated input socket on the flight box and the appropriate plug on the charger leads. One reason for this is that, if the starter uses two 4 mm plugs, sooner or later you will connect them, (the charger leads), the wrong way round. When this happens, any reversed bias diodes in the charger then become forward biased. It’s then possible that the circuit impedance may become very low, which might then make the term ‘hot wiring‘ quite obvious.     Run a separate pair of wires internally in the flight box from the socket to the battery, and on the positive leg, as near to the terminal as you can, fit an in-line fuse holder. The type designed for the continental automotive fuses are good. Put a 10 or 16A fuse in this. The reason for this is to protect the wiring in the event of a short circuit occurring in the charger. The relatively heavy fuse rating will carry any normal current. If a short circuit happens the impedance will undoubtedly be low enough to allow the instantaneous fault current to be at least towards the hundreds of amps, popping the fuse very quickly indeed.     This would be normal practise in the full-size electrical world, but there are exceptions and I have seen evidence of this. Modelling wise, recently a friend and fellow club member was charging his 12V flight box indoors. He was alerted, after about a couple of hours, by a smoke alarm. I have the photographic evidence of the carnage caused, and copies of the letters I wrote to the manufacturer concerning this, all without any replies, as always, I might add. The problem was simply the very poor standard of construction, and the quality of some of the components, of the charger, which had resulted in a short circuit and the resultant very heavy current catching the charging lead alight. And his carpet. As he said, had he been out at the time, he could have so easily have come home to find it all a smouldering heap of rubble! At the time he was, to say the least, a bit shaken; as you can imagine!     If you wire up any secondary battery, it’s always a good idea to fit a fuse to cover the wires. They can be, in these extreme circumstances, a fire hazard. That’s why you have the diode in the tx charging circuit. Even these batteries, in the right conditions, might easily be capable of setting those lightweight wires on fire. This would be very unusual, but not impossible. My MPX tx has a 2A fuse in the charging circuit, not to protect the battery, to protect the wiring.     Please, on no account consider this to be any sort of scare story. It’s just what I see as good working practise. I don’t normally lecture on these things but here I see this as a little safety point which is not usually considered. I’ve carried a 12V lead-acid battery in the back of my car for modelling purposes since before history started, well, a long time anyway; this is connected to the car charging circuit and I protect the wiring with a fuse at both ends. I’ve popped a fuse a couple of times, when I’ve donged the croc clips together, but this will never cause me any burning concerns!     If your battery uses the standard push on ‘Lucar‘ type connector, you can obtain a ‘piggy-back‘ adaptor, enabling two connections on to one.     One other thing, it may be a plan to use fairly heavy duty wires on any wiring you do yourself, the starter etc. We overcame a heli pilot’s starting problems in one go once, just by re-wiring his flight box.     Hope this may be of at least some use.                PB             

    Craig,                     If you are into reading, you will really enjoy Neil William’s book, ‘Aerobatics’. Neil was the Captain of the GB Aerobatics Team until his untimely death in 1977, in a flying accident. I watched him flying all the Shuttleworth machines at Old Warden, a long time ago, as often as I could, his Pitts and Spitfire displays particularly were seriously something else!  A lot of real low level stuff back then.     There is a smaller book, called Radio Control Aerobatics for Everyone, by Dave Patrick, published by AirAge, the publishers of Model Airplane News, in America. My copy was bought by a friend, from Amazon, in the States I believe. For about a tenner.     Another similar tome is Flying Radio Control Aerobatics, by Charles Allison and Andy Nichols. (I think!). I have seen a copy of this but I don’t own one.       Good Luck!                     PB

       One book that really stands out for me is - Wilfrid Freeman: The Genius behind Allied Survival and Air Supremacy, 1939 to 1945.    By Anthony Furse.     This is the story of the man that perhaps was more than anyone else responsible for the Mustang, he decided to buy the P51 from North American, the Merlin, when it was then fitted to the Mustang, and, of course, the Mosquito. Against a lot of opposition he ensured the Mosquito was developed and put into production, at that stage it was colloquially known as Freeman’s Folly. And he had a decisive say in the Hurricane, Spitfire and Lancaster.      It’s also a fascinating insight to the in-fighting and disagreements etc. that took place, even right at top Governmental level, before and during the War! Nothing ever seems to change!         RAF Biggin Hill.  By Graham Wallace. A delightful little paperback tale about the Battle of Britain’s most famous fighter station. Written around 1957 it relates events from 1916, when it was acquired by the Wireless Testing Park, which soon became the WEE, nothing new here then, either, Wireless Experimental Establishment, to the 1950’s. 95% content about the Battle of Britain, though.         Aerobatics.   By the late great Neil Williams.  This is about flying full size aerobatics; which can be translated in some measure to models. But there is a wealth of other detail in there, many little details and experiences.      617 Squadron: The Dambusters at War.   By Thom Bennett.  Some more legendary tales of the elite squadron.  633 Squadron for real!              PB

      Steve,         Hearing many other similar modellers tales you are by no means alone in your experience with the battery, sold at a model show. This seems to occur on a regular basis; and it’s by no means just batteries and model shows that would appear to be contributors. Engines and Ebay are just two other areas of possible ‘suspect’ activity that spring to mind.     Re. the longevity of the cells, for a variety of reasons, I only throw them away when absolutely necessary. Just occasionally, and sometimes a smidgen more than ‘just‘, when I’ve investigated power problems, I’ve found it’s not always the cells that are at fault, although the owners were generally on the point of considering that they were just junk.     Deciding on the type of cells is perhaps a simple personal choice, I’m not quite so enamoured with lithium’s as apposed to nickel. However, I think that could be a debate in it’s own right, and as I now think I should apologise for getting so far off the beaten thread here, the O/P started out as an errant engine I believe, this may not be the place to embark on that discussion.     Perhaps we should start another thread that’s more applicable to batteries and their applications, and the various peripheral units. How about “Charged Chatter” ? Perhaps even “Battery Banter” ? Or if we really want to stretch credibility, “ Watt’s Woes ” ?     The humble battery usually only gets a passing glance in the general scheme of things, but it can be very conspicuous when it goes AWOL.  A little more TLC is sometimes useful.            PB

    Steve,         Thanks for the reply. As it so happens, I checked that ‘low volts trip and reset’ on one of the very first Futaba PCM receivers a long time ago, for one of the then main aerobatics men. At that time it triggered at 3.9V, which I considered was a bit low. I don’t suppose anything has changed. All the batteries were four cell, 500mAh, nicad packs back then!     Regarding the Sanyo cells, I’ve always considered these to be about the best of the bunch. From choice, I’d pick Sanyo every time. I have six Sanyo NiMH cells in my MPX tx, which are now more than ten years old and still ‘as new’. They replaced the original MPX nicads, which failed quite early on.     One small point to consider is that of counterfeits. I’m convinced that good old fashioned genuine fakes do sometimes lurk around. Nokia had some battery troubles way back with their mobiles. This proved to be down to counterfeits, in every case. And they’d fooled even the consumer group inspectors doing the quality checks, in Belgium, I believe. I’m sure it is the top brand names they target most.     I think I’d have returned it to the seller. At least you’d have got another one. I’m also pretty sure Sony would want to know about any faults on their batteries, particularly new ones.     As with your unbranded packs, I’ve always been of the opinion that batteries can vary in quality from almost unbreakable right down to permanently broke; and, generally speaking, the average modeller doesn’t really have the right gear to sort this out. So it’s just a case of buying new and junking the old. And, as I’m now old and cynical, I don’t think that the battery industry loses any sleep about that at all……     Stay Charged.            PB  

    Mike,         Thanks for that, very interesting indeed. I suspect you must have really been into these engines, and aeromodelling, at that time. And probably still are!     Was it possible some discrepancies were beginning to creep into these dynamo results, do you think? Although the integrity of these gentleman, I’m convinced anyway, would not be in any doubt.     This was a very different age, bygone times indeed! I’d say that these people were only concerned with establishing some performance facts and figures, without any particular bias. Did they get overtaken by the speed of progress? In today’s rather more commercial world, are there any totally independent concerns prepared to organise and run such an enterprise as a suitable dynamometer for testing small power plants?     I’d have thought that because the range of modern i/c engine manufacturers is, relatively speaking, now fairly limited, that most would be known by reputation. For instance, a standard trainer, where most beginners start, has the ubiquitous 46 as a power plant. One of a choice of about 4 or 5. With the equally ubiquitous 11 by 6 ACP propellor. Or, at least that’s how it more or less is on our patch. With the greatest respect to Stephen Grigg, in his post, if you have an OS 46LA, a plain bearing cooking engine, it’s unlikely to have the performance of, say, an Irvine 46. But it is probably cheaper! The competition amongst the maker’s is fierce, I think.     In the electric motor department, however, it may be a different picture. It seems there is a bewildering array to choose from. As you said, to make a choice, a set of motor output performance figures would be a very good start. Plus a general quality check and report, such as that given by the WOO and occasionally Mike Billington, when they are doing engine tests. This might start to quickly narrow the field, I’m not sure the industry would fully approve, so I guess that’s already a non-starter then?     Closely allied to this must surely be ESC’s and batteries. Should these be getting the same treatment? Again, the choice is vast.     Anyway, the chance to reminisce about those past memories is very pleasant, looks like I shall start 2010 thinking about 1960!       Again, many thanks, and a HNY.    PB

    Tim,         Many thanks for your answer. I only raised the question because these little mysteries always intrigue me. It doesn’t seem to add up with what is current practise.     If I might be so bold, the way I would be tempted to approach this would be thus -     Waving the fuz around with that motor running flat out on the front certainly might well concentrate your attention so is it possible that you can get these symptoms without the engine running? If you can, does it form any sort of pattern? To the point that you can get it to occur on a regular basis? At that point, I would change the throttle servo. If that doesn’t effect a cure then put the servo back and then, if possible, change the rx, switch and battery. Only one at the time, and restore everything back to normal as you go along. Then, hopefully, you may be able to pin-point the fault quite quickly. If it only happens when the engine is running, vibration could be a strong contender. Same changes, same order, but carefully!  I have a feeling that opening and  closing the throttle is just part of the problem, not the answer!     Your battery. If you have a charger with a discharge facility give it a little test just to make sure it’s not totally duff. As per my battery spiel, above. Anything is possible!  Generally speaking, batteries are not prone to vibration, but there could be a dodgy connection under the heatshrink; but that would be unusual. However, I have to say, I have yet to be convinced that, when the electrical supply is cut off, the servos can actually move. I would personally discount this. This is not in anyway intended to be a reflection on Olly’s post, above, merely my own observation.     I can well understand your loss of confidence. I’ve helped to investigate the cause of many strange crashes over the years; inevitably I’ve heard the remark, ‘I’ll never be able to trust this again’.  Sorting this out will restore you back to normal.     I’m not 2.4 but I think we have 4 sets of Futaba 2.4 in our little club. Apart from one episode of very severe interference, on a petrol engined plane, which was caused by the ignition system and related elsewhere in another thread, we’ve had no reports of any problems at all. This was a separate issue altogether.     These are only my thoughts, undoubtedly there are many other ways of cracking this. And the reason for the throttle closing maybe something entirely different. But this may be a starting point.          PB