Martin

Ah... I found this: http://www.rcgroups.com/forums/showpost.php?s=475204ae4a93e631ee0e44b3786beabf&p=20690934&postcount=4094 Sounds like they provide the throttle arming function as a specific feature for electric planes, provided you use the MOTOR function rather than THROTTLE for the throttle channel. I'm not sure if that will work for this (IC) plane though, as it sounds like that functionality might replace the throttle cut functionality (which obviously I do need on an IC plane). However, that is an interesting option... I might test this out and consider moving

I've seen the MOTOR function - how do you use this to implement an arming switch? All the examples I've seen using that have been for powered gliders, with the motor on a switch - either full power or off.

Thanks for the tip. I'll try it out. I have used the throttle curve many times before. The issue with this plane though was that I happened to not have VPP assigned to any channel. I think it's normally assigned to one of the higher channels, and since I wasn't using them on other models I never bothered to change it. With this model I'm using channel 5 for AIL2, and I think maybe this is where VPP was originally assigned. Assigning a random unused channel to VPP does allow throttle curve to work, but is only an option if there are unused channels to waste in this way! That is

Wow. That looks to be a beautiful model!

I've been setting up a throttle arming switch on my Futaba 8FGS for a model which didn't have it. For previous models, I have used a switchable throttle curve: curve #1 (default) has all outputs set to 0 curve #2 (activated by switch) has all outputs set to the same as the input With this model, this didn't seem to work. Curve #1 (all zero) was never activated, no matter what the position of the switch. After much experimentation (and cursing), I have discovered that there seems to be a bug in the 8FGS software. If none of the receiver channels are set t

Thinking about it, this reminds me of a comment that the Ripmax rep made at a club night (late 2013, maybe), about an upcoming rule change that would affect FASST (but not FASSTest). The way he was describing it made it sound as though some sort of Rx-to-Tx transmission was mandatory (at which point you may as well have telemetry too). Anyway, when I asked him whether this would mean that we would be unable to buy new FASST receivers, he said that they were classed as spare parts for an existing system and so could still be sold. I'm not sure whether this is the same rule change, thoug

Wow. Thanks for the heads up!

Thanks for all the advice! I'll add 20-30g of nose weight temporarily and see how it goes.

I don't think it has flown since the tailwheel mod was done, which appears to have added tail weight.

I've been fettling the Cougar 2000 I bought off Emay some months ago. This has a non-standard steerable tailwheel which Emay had started but not finished. I've managed to tighten up all the closed loop cables so the rudder and tailwheel now move appropriately, but it does seem to add significant tail weight, which is affecting the CoG. I found a post on RCGroups http://www.rcgroups.com/forums/showthread.php?t=115294 which lists the manual-recommended CoG as 100-115mm back from leading edge. When I picked the plane up I also measured where Emay had the CoG on his other Cougar, w

Now SOLD. Seagull Boomerang II 4-channel IC trainer The Boomerang is widely recognised as one of the best trainers currently available (ask any instructor at the club and I'm sure they'll agree). Fully built, set up, and ready to fly - just add 4+ channel receiver. Can be seen flying at field. Very reliable OS 46 LA engine (I've only ever had one dead stick in over a year, and that was due to running out of fuel!) JR 591 ballraced servos (x4) Sanyo Eneloop flight battery Upgraded dural undercarriage Steerable tailwheel External charge socket APC 12x4 pro

How about a capacitor with a diode to prevent discharge other than by the Rx? Since the speed controller is totally independent of the Rx (being mechanically controlled by a servo) I can't see a reason why not. You'll lose an extra 0.7V, but if that's a big problem you're cutting it quite fine anyway! A 200mA small signal diode would probably be sufficient (getting quick switching), relying on the 1A/2A surge rating for the times when the servos are actually operating. I'd guess that the main problem would be the size of capacitor needed, as while you can protect against the motor drai

They may well improve over the first few cycles. Is the device designed for rechargeables or normal primary alkaline cells? If the latter then the 75% may just indicate the lower voltage of rechargeables - I have a DAB radio that I use 2x AA Eneloop in, and fully charged cells only give me 2 bars out of 3 for battery due to it expecting fully charged to be 1.5V not 1.2-1.3V. If the batteries are permanently attached to the device without a proper hard power switch (that physically disconnects the electrical path), then this may just indicate general consumption by the device. I have a digi

How are you measuring the charge lost, and for how long does this keep happening? As I note in my reply to Trevor, if you're measuring this by how much your charger wants to put back in, this probably has more to do with how quickly the charger can actually detect the end-of-charge condition. I expect you'll find the batteries slightly warm to the touch at the end of charge, which is normal for NiMH - when a cell is fully charged the extra charge flowing produces gas, which is converted back by a catalyst, wasting the extra energy as heat. (This is also why NiMHs don't need balance chargin

All of the low-self-discharge NiMHs will lose about 5-10% quite quickly. The difference with normal NiMHs is that the rate then slows down. The exact rated discharge rate depends on the generation (newer are better): https://en.wikipedia.org/wiki/Eneloop. Eneloops are also only charged to about 75% in the factory, which corresponds to a point where the self-discharge is very low (if they charged them to 100% it would be a waste as they would be down to 85-90% by the time they were sold). The main explanation for the top-up after a month, though, is probably more that it's the amount that t

If you want something that shows all the possible variables in an electric power system and how they interact, have a look at the calculator on http://rcadvisor.com/. I've also got the book by the guy who runs this site and wrote the calculator, and it's pretty good on the subject of specifying electric power systems.

Stepper motors have been around for a long time. They have the advantage of being quicker and more precise for small movements (which is why they're commonly used for CNC machinery). They do have some disadvantages though: * the risk of losing steps, if the load is too great or the steps are too quick (which would then mean your control surface is permanently out of sync with your TX, probably causing a crash in pretty short order) * the related problem that if the surface is moved while the power is off, it will be permanently out of sync when the power is back on * slow speed for large mo

This thread has a discussion of various other names that they go by... http://www.rcgroups.com/forums/showthread.php?t=778177 Martin

On a vaguely related note, I remember seeing an odd suggestion in a book on model engines (which I think must have dated from some time when nitromethane was much harder to obtain). This suggested using a small percentage of petrol instead of nitromethane (e.g. 75% methanol, 20% oil, 5% petrol). This doesn't really make sense to me, since the point of nitro is to provide oxygen rather than significant calorific input, while petrol would do the opposite. Given that as Dave notes the most noticeable effect of nitro is on quality of idle, perhaps the petrol acts in some different way to keep

Looking at the numbers in the table in the PDF, it does appear to be a table of the "diameter squared times pitch" relation.

I've got several spare unused Seagull Boomerang tanks. I can measure one tonight or tomorrow if you're interested. I'm not sure of the exact capacity, but they're big enough to keep an Irvine 46 running for over 15 minutes at mid-throttle. Martin

If "weather permitting" means it mustn't be raining then it might happen in about a fortnight...

I've removed the grub screw and the circlip. We all had a look at it at the field. The problem is that because the shaft is bent rather than broken it's catching on the bearing when we try to pull the case off. (The case will move 3-4mm then snag.) I could potentially just apply brute force, but risk damaging the bearings.

I've bent the shaft on mine, and the old shaft doesn't want to come out. Quite a few of us had a go at moving the shaft at the field last week without luck. The next step is to try cutting off the bent bit with a Dremel and pushing the shaft out the other way. Before I get round to that, I've decided to buy a new motor to get the plane flying again (so I can faff with the old motor at leisure). It seems to be hard to obtain the XYH motors at the moment - GiantShark list them all as "special order" (and don't list the 910kv one at all any more). There are two motors at HobbyKing that se

Do you think that the sloppiness of the tail gear is the only thing preventing the gyro from crashing it for you? Martin