Nigel R

If that was using torque rods on a low winger, then some forward rake of the horns (as in, the torque rods themselves) is correct for that setup.

If it fires, runs and dies, it feels like a fuel/carb issue. My first bet would be gunk getting into the carb. Old fuel can congeal. Lumps of gunk throw the tuning. I'd be tempted to pull the carb, remove needles, give it a soak for a few days, and reassemble. 48fs had twin needle carb IIRC, and the needles are not usually loose. They have the internal O ring, the fuel tube dodge won't work? Might be worth changing the O ring for a fresh one.

Personally, I wouldn't worry about it on that size/type of airframe. Another alternative, you could (carefully) run a thin bead of silicone sealant along the hinge line, to fill the gap. Mask off the aileron first, mind.

Ah yes - Magnum GP40 - part for part compatible... I have two FP 40s, both with Magnum GP piston, liner and rod, which run just as well as they ever did with all OS parts 🙂

No, my bed isn't glass. Sounds like a small upgrade may be in order.

Thanks for link to the vid course PDB. Bookmarked 🙂 I'm just using cheapo PLA on an Ender3 with pre-rolled designs - very early days for me with 3d printing though and yet to truly get to grips with it. The Ender is sloooow but seems pretty capable and is incredible value. Mine has a very bumpy print bed however which I have struggled to get flat. I'm ok with small area prints but anything bigger than about 5" x 5" starts to get sketchy adhesion. Any recommendations for a worthwhile upgrade here?

I hazard to suggest that a half second throttle response is the least of your worries if you're that marginal. Anyway, the point of the 'slow' is to get the throttle to follow the fastest pickup your engine can manage after an extended idle. It's a last resort of throttle tuning after getting the needles set as good as you can. Put it another way, what's worse for your bin bag scenario? The 'slow' response (which if set right is as quick as the engine can manage anyhow), or opening the throttle - and getting the sound of silence? Smaller carbs do seem to be easier to manage. One of the best glow engines I have owned, in terms of throttle response, is the old OS 40FP, which has a tiny carb compared to most 40 size engines (and it's only a single needle air bleed, too). It's smaller than some 20s even. And the motor will idle and idle and idle and then snap to full throttle quite happily.

Sometimes it is difficult to get an acceptable balance between ideal idle setting and ideal pickup setting. Plus engine temperature affects the ignition, as JD8 says a minute is plenty of time for the engine to cool down. And we don't have accelerator pumps so cannot compensate with an extra dollop of fuel when the throttle is gunned... Servo slow is a pretty good feature to take advantage of on modern radios.

Never tacho'd an idle for anything other than interest. Just go for the lowest that you can get it reliable. Reasonable excuse to add some flaps?

Hold on - it's legal to drop an animal from a model plane? Guinea pigs with parachutes anyone?

Another happy customer of RC Japan here. Bought some OS spare carb parts a while back. Yes, definitely Japan based! Speculation... If you're inside Japan you probably get a website in Japanese... If you're outside you get English or Chinese options...?

Can't add much to the above excellent posts, low angles up to 30deg give lift for takeoff, over 60 deg is an airbrake. Both settings are useful in their own way.

Fitting dual servos for ailerons became commonplace in the 1990s, I would say. I remember at the time (20g size micro servos were still pricey) I used two standard size servos, probably S148 or JR 507, in several 40 or 60 class airframes. Before that, historically, I think central single servo with bellcranks and barn door ailerons were de rigeur for good while (1960's?) before torque rods and strip ailerons became common (70's?). These days of blow moulded foamies and near disposable price electronics, its simply too easy to dig out a hole in the foam and hot glue a 9g sub micro servo in place.

If I'm using two servos I'd use two independent RX channels - no point not... unless I'm stuck with an RX without enough channels. That said... Anything I build myself I usually fit a single standard servo, torque rods and strip ailerons. Differential (if needed) is easily possible via offset servo horn - as Paul's post shows. Old school? Sure, but, works, hidden linkage, looks tidy, happy with end result. On a fun fly or 3d type, you may very well need the two channels for elevator/flaperon mix. On something larger/faster/pricier you probably want redundancy. Something ARTF is probably built with holes for two servos. Horses for courses.

1.8m of Piper Cub will fly on a 0.25 two stroke, so I'd be keeping this as simple as possible, I'd fit a 2000mAh Eneloop AA pack, just one of them. Do get a new pack and bin that old one!

Absolutely this. Businesses provide what people want, if they can make profit on that endeavour.

Might be tiny air bubbles in the oil? Seems odd at first for a bike to spec ATF in the forks instead of regular fork oil, but I guess the viscosity must be matched to the fork's assorted valves.

Agreed on dry storage. I have had one engine stored with ATF gum up. Maybe it reacted with something in the fuel? After that I pushed the boat out, spent £10 on some air tool oil, use that for my infrequent assembly/storage jobs instead. ATF is not hygroscopic.

Cells can fail shorted. Yes, wiring can also short. Failover device like the 'ideal diode' linked by Phil provides protection against both. Even if a first failover devices fails with a dead short, the second failover will prevent the first problem from affecting the second pack. If a first failover devices goes open circuit, the second is there for backup. "chargers can fail" I think I said, or words to effect. Your models, your choice, etc.

What is "enough" power is down to the individual, I'd say. My own stuff, I have airframes from an electric trainer which just about loops from level up to 3d. Make sure it won't fall apart, have at it.

Given the Joker's era, Matt probably expected to use a 12x12 prop?

Far more problematic than the above scenario, is that cells can fail to a dead short. Two cells in a vanilla parallel arrangement have no protection against that.

Quite normal - AC is always rated much higher - the voltage crosses zero so any arcing naturally disappears quickly. The direction of erosion, from the arcing, also varies. DC arcs take longer to die out. The erosion is always in one direction. Hence the lower rating. As noted by Andy and Brian: We only use 5V or thereabouts - not 125V. When you switch off an RX, normal situation, all servos at idle, any current through the switch will be very low, 100mA or thereabouts for "your average sport model" (well within the current rating even at 125V DC). If the current isn't very low, you almost certainly have bigger fish to fry (stalled servo? burning servo?) and any small arc that may result from a 5V (ish) contact break is a bit "down the priority list" as it were. Sure. Many assumptions; it is an abnormal scenario. Nimh cell resistance is usually quoted as between 30 to 100mO - going to assume 30 for now. Cell #1 is charged perfectly to peak. Voltage will be quite high. e.g. it will read (maybe) 1.8V. When it is disconnected it will almost immediately drop to around 1.5V IF Cell #2 has been overcharged for whatever reason. If the peak during charge was (the same as cell #1) 1.8V and then charge continued until the cell was 1.6V. (that would be quite the overcharge, but, chargers do go wrong) When Cell #2 is taken off charge it will drops a comparable amount to cell #1, say to 1.3V. Now parallel them up. Initial current, (assuming the usual simple internal model of a battery) Vdrop = 0.2V, Rtot = 0.06Ohm ( 2 cells in series with 0.03Ohm each). Gives I = 3A The discharge curve at this current (1.5C ish) is sharp and of course, cell #1 terminal voltage will decay quickly. How quickly? Minutes, around 5 minutes or so. Within cell #2, the terminal voltage will also fall, but slower. The situation will self limit. There isn't enough energy in cell #1 to sustain the scenario. Meantime, further overcharge + temp rise within cell #2. Significant? Maybe. Depends. Likely outcomes 1) some further damage to cell #2 2) your power source is now busy self discharging and doesn't have much spare capacity to run the RX + servos.

No, not what I said: Anyway. Do what you want, this is just a discussion, no need to get upset.

Is the temperature change due to these reactions significant Mike?