Jonathan M

Update: all issues now sorted and, after several more runs on the ground in the last week, finally maidened the Acro Wot today! (Lovely model, a real pleasure to fly! Did I mention losing it for a few tense moments in the low cloud!?) The ASP 70 FS settling in nicely, still with the smaller 12x6 running-in prop and still lots of smoke and castor oil residue streaming over the wing, but with a fairly reliable tickover of 3500, slow enough to land into a light wind whilst avoiding the worst of the sheep-shit and the forest of mole hills pocking the patch! Second flight we topped up the tank (say 50:50) with a mate's fuel containing 5% nitro. The idle seemed better as did the transition with the risk of cutout almost completely gone, but at full throttle the engine seemed to vary a bit in note and speed? Should I stick with the Model Technics Special Four Stroke 0% nitro, or for my second gallon get the 5% nitro version? Also, when would it be 'safe' to fit the 13x8 prop? Jon

I've finally decided to start the Middle Phase with aileron wing as my first proper build. (I do a bit of regular DLG thermal hunting with a 1m Elf and a soon to be completed 1.5m Blaster 3, and have cut my teeth on the slope with a lightweight Libelle... which is otherwise floppy and certainly useless for DLG!). Although I've garnered much from various MP threads here and elsewhere, I have a few residual questions before I commit to butchery or spending any more money! The supplied snakes look a bit basic and I've got a spare gold-n-rod to use for the elevator, but would a closed-loop be superior for the rudder on this model? Will tape and glue micro-servos in the wing at the centre of each aileron, line the cutouts with 1/32 ply, and run the extension wire forward into a channel behind the LE strip. Will a budget servo like a HS-81 be up to the job, or a mid-price HS-85BB or a dearer HS-85MG? (I'm happy to spend my ill-gottens on quality, but only if really necessary.) What servos would I then need for the rudder and elevator? When I originally bought the kit my LMS originally bunged me a couple of Futaba S3003 servos (but I later diverted these for use in my Acro Wot ARTF). The two marginally dearer options are the S3004 and S3001 units, the latter being a bit heavier still. I suppose bearings are good, metal is good, both is even better... or overkill? What are the equivalent Hi-Tech servos? Going for maximum strength and longevity, I'll be inserting a couple of ply braces in the wing before applying the fibreglass belt, and I'm also inclined towards rubber bands rather than nylon bolts to secure the wing, but with a nylon bolt for the stabiliser. Also, in the event that I wish to experiment with ballast on windier sites (6 to 10oz), I intend to fit in a ply-box at the fuselage CG. Covering. This is where I'm really in the dark. I want a tough fuselage (including at least fibreglassing the underside as far back as the rear wing seating), but don't want to overdo the overall weight. I'm attracted to using Poly-C rather than epoxy, but don't know in the slightest what weight of cloth to use for this or the whole fuselage? Could I then glass the wings and tail structures using lighter weight cloth (what weight?) then spray paint? Will this all add up to an elephant-full of weight, so should I use iron-on film for everything - and then what type and/or different products on different parts? Cheers, More-questions-than-answers-Jon

Posted by Tom Sharp 2 on 26/12/2016 23:34:02: How to make God laugh. Tell him your plans for the future. Yeah, and if you have enough on your list, one might just maybe slip through un-noticed...!

1/ Finish what I've started: - Get Acro Wot airborne and improve flying skills at the patch, - Get Blaster 3 complete (almost there!) for DLG thermal work from any old field, - Get Middle Phase kit (aileron wing) out the box, build it properly and get slope soaring. 2/ Start building (and complete in time for this year's BMFA Indoor Nats): - Peck Polymers 13" span Andreason biplane for Peanut Scale, - Aerographics 18" span SE5A for Kit Scale.

Chris, John, Dennis, et al - many thanks! The last bit of missing info was setting the low-voltage limit for discharge... now I know. Might yet get a battery-load tester. This one **LINK** loads at 500mA for 4.8v rather than the 1 or 2amps suggested above, but I'm unlikely to ever go larger than a 40 or 60 sized IC. Interesting however to note that my two batts both show a higher remaining capacity when the meter is put directly on the battery rather than via the switch lead! Learning absorbed re capacity and charging efficiency. I've removed the big 'un (which required butchery to get out) and will fit the smaller Eneloop (in an easy to remove padded sleeve) plus only as much lead as is needed to balance.

Thanks for all the helpful feedback. So, from this, as well as an earlier thread on this subject, plus a dose of advice from a randomly-found Tamiya forum... Some charge at 0.1 while others at 0.5 or 1.0C, although low C-rates run the risk of the delta-peak not being sensed, leading to overcharging. If in a terrible hurry then up to 1.5C is possible but 2.0C is cruel. A good compromise between charging-time and battery-life is 0.5C. Delta-peak defaults (for NiMH) seem to be set, depending on actual charger, at 6 or 7mV per cell (roughly half that of than the more tolerant NiCds). The Tamiya boffin uses between 3 and 6mV per cell, with a max of 8mV for older batteries. He says batts are all different and one should experiment, starting from a low setting: if charging stops but the battery isn't warm, then its picked up a false peak and the setting should be increased. Warm is correct, but if the battery gets hot then its overcharging. I like the idea that cycling isn't something that's terribly necessary with NiMHs, but once a month certainly seems sensible. By the way, my only rationale for fitting the 260g Sub-C 3800mAh pack below the fuel-tank in my ARTF Acro Wot was because, despite the 70FS up front, it was coming out tail-heavy (like all the ARTF ones seem to!) but now it needs 50g of tail-weight to balance. Yes, fitting the 110g 2000mAh Eneloop would save 150g up front, and I can then lose the 50g from under the stabiliser, but would need to add lead back to the nose (with its much shorter moment) to re-balance. But, for a model that is bang on spec at 6.25lbs (2.83kg), a net 100g saving only represents 3.5%.  I might yet do this, or maybe I'll just move the 3800 back a smidge into the radio bay - where at least I'll be able to monitor its temperature during charging! Happy Christmas to all! Mithering Jon  Edited By Jonathan M on 24/12/2016 19:34:03

For clarity, this is the NiMh charging options flowchart: One thing I've noticed is that the Discharge options require you to choose the total voltage of the pack, whereas the charge options don't - I assume the charger simply senses the voltage here?

With apologies in advance for so many questions, but having moved from LiPo-fuelled electric foamies (with that whole learning curve!), I'm keen to now understand and look after NiMh batteries. This is for my first IC, an Acro Wot with five Futaba S3003 servos and a Spektrum RX. (I've trawled through many pages of threads in this topic and garnered many useful bits, but thought I'd pose my questions as a complete set - which might then be of use to others passing this way in future.) Q1. Will a 4.8v pack be sufficient for this application, or will 6.0v be cleverer - more torque, less risk of brownout? If 4.8v is adequate, then what is the dis/advantage of a pack with greater capacity - i.e. a 3800mAh pack made up of four physically larger (but heavier) cells over a 2000mAh Eneloop with its four AA sized cells? Q2. My 3800mAh 4.8v pack (I chose the heavier option to avoid adding the usual nose-weight to this ARTF) was purchased new and fully charged. After a bit of use during installation, setting throws and then forgetting to switch it off for a few hours, it is now down to 4.9v (five bars out of seven on the battery checker), so about 1.0v per cell. Is there an absolute minimum voltage below which the battery will become damaged or can one just let it drain down in use? (Obviously I wouldn't want to fly with capacity below, say, 25%.) Can I safely charge it back up from half-way, or should I cycle it fully down and back up again, and should I do this every time or just the first few times when the battery is new? Q3. I have a Fusion Elysium charger, manual here  **LINK**  which gives me lots of options, but I'm unsure what settings to use for safety and longevity of battery pack. (i) Charge Current. I gather 1/10C is the correct setting, certainly initially,for NiMh batteries, e.g. 0.4A for the 3800mAh pack, which from empty will then take about 10 hours, i.e. overnight. Should I do this every time or can I use a higher C (1/5, 1/2 or 1C) once the pack has had a few cycles? (ii) Delta Peak Sensitivity. To what level should I set this? The available range is from 3mV to 25mV per cell. (iii) Discharge Current. To what level should I set this? The available range is from 0.1 to 1.0A. Is 'fast' bad? Just how slow? (iv) Discharge Cutoff Voltage. To what level should I set this? The available range is from 0.1V to 16.8V in total. (v) Cycle settings. I don't fully understand the menu options here. I can toggle between D->C and C->D and can, for each, choose between 1 and 5 in 1 unit steps, but I don't know what these mean. Does D->C mean from 'discharged' to 'charged' and vice-versa? Which setting both discharges and then automatically charges, or is this something I have to do manually (there are also separate charge only and discharge only menu screens)? Do the numbers mean total number of repeated cycles or something different? Specific help with some, most or all of these questions would be hugely appreciated! Thanks Jon Edited By Jonathan M on 24/12/2016 13:05:52

Justin, Denis - thanks for this! Especially good to know the idle will settle down after a few flights. With the tank removed from the airframe, but before removing the bung or any of the neoprene tubes, I tried a pressure test by nipping off the filler and pressure tubes and blowing down the fuel tube. I couldn't detect any leak... but I did then get a serious blowback of residual fuel right down my gullet - yeuch!! The likely culprit then emerged: the clunk tubing was actually too long, especially after it had slipped slightly off the copper pipe inside, and was sitting right against the back of the tank.  It also didn't help that my test was done on a slight downwards stope in the garden, thus with the nose slightly down - didn't think that one through!  So, I've cut 7mm off this and re-installed the tank (which is a Dubro rather than the Ripmax effort).  Will test/replace all the external tubing, lose the filter, and run the engine up again tomorrow... on the flat! Edited By Jonathan M on 22/12/2016 20:56:45 Edited By Jonathan M on 22/12/2016 21:01:14

Things getting much better: slow-speed mixture now set okay so that throttle transitions up and down without faltering, although can't quite get idle speed low enough. But seem to have another problem in that the fuel supply sometimes falters due to visible air pockets travelling up the fuel-line, even with a reasonable amount of fuel still in the 10oz tank. If the air pockets are excessive then the engine cuts completely, especially at lower revs when vibration seems to be greater (hence the problem with dealing with the slow-speed setting above). This happens with the model static on the ground and I don't know - if vibrations are the cause - if the same thing will occur when the model is eventually in flight, and with the fuel system being subject to dynamic forces as the model manoeuvres. The model is an Acro Wot ARTF and the brand new fuel tank will need to be taken out (the usual hassle) in order to check for air-leaks. The clunk tube was cut so the clunk cleared the rear wall of the tank by about 10mm, and I tightened up the bung-screw pretty well before installing. The filler tube has one of those plastic cut-off clips and the tank is pressurised via a tube from the silencer. The only other element in the supply is a brand new fuel-filter between the tank and the carb. If vibrations are the cause, then surely the tank should be held in suspension from the airframe using foam?

John I wouldn't worry too much about the ONE visit thing, which is probably (based on their experience) aimed more at deterring casual fliers from accessing their patch for free than putting off genuine prospective members. When the weather improves, mosey on down a few times and chat to the people doing the actual flying - mostly ordinary, welcoming folk just like you and me. Jon

Posted by Robin Colbourne on 22/12/2016 02:22:23: ... If would be flyers don't know where to find you, then you have to go and find them. As you said, all the nausea of child protection rules out the younger end of the potential recruits, so you need to find the older ones. Do a bit of brainstorming of groups who may appreciate a visiting speaker. A few examples could be the British Legion, the Civil Service retirement fellowship and full-size aviation groups. Try and persuade the most charismatic member of the club to do the talks, and cover as many of types of model as possible. You never know, even members of the Women's Institute may be looking for ways to get their husbands out of the house.... Local newspapers are always looking for interesting articles to fill the pages, so an article about the club with the offer of hands on flying of a buddy box equipped trainer should bring some potential members out of the woodwork. Offer a few alternative days, as some people, particularly those with families, may have standing commitments at weekends. Robin, thank you for a whole roster of very useful ideas! There is evidently much we can do to raise our profile at little real expense or effort. Its not a question of some ambitious plan to double in size, but one of 'feeding the hopper' now, so that in x years time we don't suddenly find ourselves with too little critical mass to remain viable. Jon

Posted by Tipsy Pilot on 19/12/2016 23:20:30: I have a feeling the same circumstances exist here in Australia. I had my interest in the hobby lifted by a work colleague who owns and flies models, discussion came up at the lunch break and I mentioned I had tried many years ago to fly models (control line) and failed miserably. Anyway he gave a few suggestions which I researched on the internet and before I knew it I was walking out the door of a good hobby shop with an apprentice, a simulator and an ear full of very good advice about contacting a club as well as where I could or couldn't fly (plus a little advice on the law). Anyway I really wasn't keen on joining a club, firstly because of my work arrangements (I'm away for two weeks of every three) and secondly I really didn't want strangers telling me what I did wrong or what to do or not do when the inevitable crash happened as the hobby shop owner advised me would happen 😄. He also wisely said the best way to not crash was to not fly. About 12 months later after many hours on the simulator and a few good hours of flying time on my own I thought I was doing just fine on my own. By this stage I had also become keen enough to start researching the hobby more, after all I wanted to get better at it and with all things that means a bit of research and study. That's where publications like RCM&E come in. I was reading a magazine on drones in Australia and one article in particular opened my eyes, it was about changes to the aviation laws with regards to drones/multirotors but also touched on RC flying machines in general. Suddenly the advice from the hobby shop owner was again ringing in my ears about joining a club and flying sites. Uh oh, time to find a club before the law found me. So now I'm joining a club, plus I have another work colleague who is as keen as me and he's joining as well as a complete novice. So what's the secret to growing club membership? I think it's awareness. Thanks to a good, responsible hobby shop owner (whose advice I almost ignored) and a magazine publication I have been made aware of my responsibilities as a model flyer and in order to be a better pilot you need peer advice, therefore clubs are a must. The hard part for clubs is putting their banner in the face of prospective members, I think that just comes down to advertising in whatever form that may be. Websites, magazines, community events....... whatever it takes. Best of luck to all clubs. TP Good post Tipsy

Excellent explanation Peter, thanks, and Stuart et al also. Every component in a chain is always a complete new learning curve! Already ordered a power-panel. Useful however to know the built-in meters can't be relied upon, but this can of course be periodically checked/calibrated at the plug end of the lead with a hand-held multimeter.  Don't want either 1v or 12volts! Have also ordered a 2000mAh sub-C replacement for the little JP unit as a backup power at the field. Will see how charging and ability to hold the charge works. Edited By Jonathan M on 20/12/2016 13:06:37

Hi Martin - Contacts completely clean, voltage same when measured at head and at battery terminals. Just ordered a couple of OS F plugs as spares, so can compare them in use to the ASP plugs. By the way, when the glow was powered from my mate's power-panel the engine started with a hand flick first time, whereas this was never possible with the battery-stick even when fully charged.

Posted by eflightray on 19/12/2016 20:41:27: If I remember correct back to my Nicad/Nimh flying days, those types of cell do not really like long low amp charging, they soon start to drop the voltage under load and wont hold the capacity. If the cell is suitable, then a high current charge may reinvigorate the cell What charge would you suggest?  Using the hot-wire method above, I might try to resuscitate the 3800mAh NiMh cell...? Edited By Jonathan M on 19/12/2016 22:43:12

Thanks for the various observations - good to know the meters are all pants. Clean unit, direct clip-on, barely used. Plug is a new ASP unit for 2 or 4 strokes (used in an ASP 70 FS). Interestingly, a few hours now since ending the 24hr charge, I've just checked and the voltage has fallen back to 1.38v. Will check again tomorrow morning where its settled. Could get a couple of replacement cells and hot-wire (excuse the pun) the charging-head and leads from the wall-charger to my proper charger (Pb/LiPo/NiCad/NiMh) and select an appropriate charging capacity. Or - more reliably - I've decided to complete my flight-box properly with a 12v power-panel with adjustable current to a lock-on glow-lead! Cheers Jon Edited By Jonathan M on 19/12/2016 22:40:26

Got one of those 'handy' JP Glow Starters with a rechargeable 3800mAh NiMH cell, but don't seem to be getting much glow out of it after a few starts?! Abandoned using it at the field yesterday when it failed to get the plug hot enough - luckily a mate had a lead clip plugged into his 12v power-panel. At home the battery registered 1.27v on the multi-meter, which went up to 1.35v after 3 hours charging (240v wall-charger rated at 1.25v 170mA, however 1.85v on the multi-meter), then 1.41v overnight and finally 1.43v after 24hrs. Do these voltage levels make sense? Even after a full charge, the unit's integral meter needle is barely out of the red-zone. Surely a 3800mAh battery should hold a heck of lot of capacity, and the meter should read higher?

Model Monster - a useful post, thanks. It seems that a good website, plus the offer of training, is an important component. Jon

Thanks folks for the helpful input. Yes 'quality' is important (and we've got some great members, plus many regulars who drive from up to an hour away to enjoy flying from our site, as well as the odd divot), but the question will eventually be one of a viable minimum of numbers. I'd love to be able to muster some interest from the local secondary school (1,800 kids plus 140 staff - if only 1 in a 100 showed any interest that would still be 20 people!) but the issues surrounding child protection are way too much for us to handle. Yes, the ironic thing is that cheap RTF electric trainers makes getting into the hobby so much easier than ever before (no kit building or IC to worry about), but most people would still need the training, friendship and support that a club offers if they are to get anywhere beyond a bin-liner full of smashed foam. Jon

Our club has a fairly small membership (circa 50), with numbers shrinking very slightly rather than growing year on year - not enough to prejudice survival in the short-term but certainly a longer-term concern, especially due to the average (older) age of most members. One of our problems in attracting new members who need basic training is the relative lack of instructors. Also, although close to a growing town in Middle England, we simply don't have the skills or inclination of the already busy committee to deal with child-protection, so that seems to rule out attracting family people, let alone youngsters. I'm prompted to post this, having read the editorial in this month's RCM&E - where David Ashby notes the significant uptake in new applications to his club a couple of years' ago after their new website went up. We're lucky to have a good site with no noise or time restrictions. So, what aren't we doing right, what's the recipe for moderately growing members? Cheers Jon

Percy - thanks for these additional tips. Pre-adding a stiff member to the snake outer would have put me in the same position really as just using the rigid, wooden dowel linkage provided. I wanted to try the Sullivan system, but only discovered the flex (on push) after it was installed, and didn't fancy the idea of a sloppy elevator linkage in the air! I went for the heavier 3800mAh pack as earlier posts in this thread as well as David Ashby's 2012 review ( http://www.astramodel.cz/manualy/ripmax/ripmax_A-CF006_Review.pdf ) indicated considerable tail-heaviness in the airframe as manufactured and the need for loads of nose-weight. As it happens my AUW of 6lb 4oz, including almost 2oz of tail-lead, is still under the 6lb 10oz of David Ashby's model with the same engine, plus I get longer between charges. Justin, Steve - thanks for this most helpful advice. My TX is a the new-ish (black) Spektrum DX7 so all sorts of programming and mixing options are available. So far I've set up a three-position switch (same one as I use for electric for consistency) with throttle closed on two positions and active (from general idle onwards) only on the last one. I do like the idea of a slower idle for landings, so can easily re-programme for fast and slow idles. Failsafe is currently set up for level flight and to cut engine altogether, but I really like the suggestion for engine idle rather than cut-off. (If there is a controversy here, then my own view is that an uncontrolled plane is no more dangerous with an idling engine than with a dead one, plus a plane with an idling engine can be more easily flown to safety once signal is re-established after a brownout.) Also, re slowing for landings, our patch isn't huge - plus there are too-frequently mole-hills to avoid - so I've followed a suggestion much earlier in this thread and programmed in a mix of slight down 'flaperons' with a tad of up elevator to produce a slight nose-up attitude. When I eventually get to maiden (today was perfect but had to be cancelled due to stuff from... err... the Missus), I'll fine-tune this at height! Cheers for all the help Jon Edited By Jonathan M on 11/12/2016 18:09:36

Posted by Percy Verance on 09/12/2016 19:59:30: And if I may offer some further advice Jonathan, I'd put a locking nut on the servo end of the elevator snake. That will eliminate any chance of the snake itself unscrewing with engine vibration and becoming disconnected. Cheers Percy - no nut available, but a dribble of Loctite seems to have done the job. Final weight (dry tank) came out at 6lb 4oz (2.85kg) including 50g of lead under the tail to bring the balance point to the specified 83mm from root LE. I was worried about the big 3800mAh 4.8v battery I installed in the tank bay (opposite side to the engine cylinder to redress that imbalance), but I did this as I'd read about people usually having to add much lead to the nose to counter inherent tail-heaviness. So, is this weight reasonable for a 70 FS powered version, or a bit too heavy really? A question also on setting the throttle (as only ever flown electric so far): i.e how is 'throttle-cut' set up on an IC? Do I set the normal throttle travel to range from tick-over to fully-open, then programme a 'kill' switch to close the throttle completely? What about 'fail-safe'? ??? Edited By Jonathan M on 10/12/2016 23:30:11

Thanks Jon - very clear explanation and great video! Jolly useful having an accessible knob for the slow run mixture on your Laser engines, rather than the fiddly screw-head on the ASP (which now points downwards on my side-mounted unit). I haven't had time yet to run the engine again (albeit now in the airframe), but I think you're right about the slow run being too lean: I followed the instructions to re-set it to the factory level, which turned out to be some way out (i.e. a richer starting-point) from where I had been running it in previously. Will see how tomorrow morning's test-runs go. Jon