Martin Harris - Moderator

You can, but it’s more efficient to reduce the load by using either a smaller pitch or diameter, appropriate to the model.

There are a lot of variables but could you borrow a few props for testing from fellow club members? Many long established modellers are likely to have a stash - redundant IC props would give you some ball park indications too.

A 5mm shaft suggests a reasonably capable motor. Power capability of a motor relates closely to heat generation/dissipation. With no motor information, you could adopt a trial and error process, gradually increasing prop size and/or cell count, monitoring motor temperature after short - then longer - runs. For safety, the motor shouldn't get hotter than you find comfortable to touch. Work from behind the prop, as you would with IC and disconnect the battery between "finger" tests... A Wattmeter is invaluable for experimenting with motor and battery combinations so beg, borrow or buy one if at all possible!

Hope you're planning to stick around on the forum - would you like to change your name to something less specific?

Yes - a couple of lessons to be learnt here. One is to read the thread title more carefully and the other is to post important info about a question in the original post! Well spotted though Brian. If the 7c can’t be programmed to reverse surfaces in its elevon mix (I would think just a matter of setting direction(s) from + to - or vice versa in the mix) and a physical reversal is impractical, then it may still be possible to obtain (or build) an electronic servo reverser. You might also bear in mind that some servos operate in reverse rotation e.g. Hitec do (or did?).

Hmmm - still ok on the other models? Sounds like memory corruption then. Perhaps clear the memory and reprogram from scratch? However, it doesn’t make sense that swapping the servo connections didn't make any difference!

I don’t know whether channels can be reassigned on the 7c but you could just swap the servo plugs in the receiver channels. Is this a new radio or have you bought it second hand? Maybe the internal connections have been swapped?

Which receiver channel do you have each function connected to? Futaba usually uses 1 for aileron and 2 for elevator.

A few words of praise for HobbyRC - I ordered a couple of ESCs and a programming card from them yesterday, just before their 16.00 cut-off deadline. 19 hours later, they arrived safely. Refreshingly, the P&P charge for 24 hour tracked delivery was only £2.95 - quite a contrast from a well known and often recommended supplier who added postage on each individual item on a recent order - totalling just under £8 for a similar sized - but standard service - package a week or so ago. I do find some supplier’s postage charges so annoying that I will abandon an order and look elsewhere when I come across these hidden added premiums.

Slow blow fuses use a "blob" of solder as the fusible link, situated between a spring on one side and a plain wire on the other. They are obvious with clear glass types but are usually prefixed with a T for identification whereas "standard" fuses will be marked with an F, e.g. F1A for a 1 amp fuse. Rather than a thin fuse wire melting instantaneously when too much current passes through them, there is a time delay while the solder heats up before melting - when the spring pulls the connection apart with a large enough gap to prevent the possibility of a sustained arc. When a lamp filament first passes current, its relatively low resistance can blow a fast blow (ordinary) fuse but once the filament is glowing white hot, its resistance is much higher (this is where the specified wattage is quoted) so that the current reduces sustantially. It's very quick but if you've picked a value of fuse based on the lamp wattage (i.e. by calculating the current at a particular voltage) then you might have unexplained fuse failures.

I've taken the liberty of amending your original advert to avoid any confusion now that the engine's gone - hope that's OK?

My recollection is that the previous aborted landing from below 10 feet was thought to be of limited value and rather too simple for a more advanced test and rather a waste of effort. The collision avoidance is just that - the assumption being that in a real life situation, the pilot has detected the hazard in peripheral vision and assessed the need to avoid the hazard safely in a controlled manner and return to circuit height. In other real situations it’s possible that it wouldn’t be the appropriate action. The manoeuvre is one of a controlled aborted landing with a change of direction - effectively a demonstration of a safe climbing turn from low level. It is certainly not meant to be a pylon racing turn!

Thanks for the ideas Brian. I established an input range of 3.9 - 6V which would work using an adjustable power supply connected direct to the board so I can discount battery or connector issues. Funnily enough, I did wonder about the ground connection and tried a link across the board but that made no difference. It’s so strange that I’ve had these problems and I’m perfectly prepared to find that I’ve done something incorrectly but I’m at a loss to see what that could be with such simple circuit connections. I’ve built two examples (both from the instructions, not copied) and they both show exactly the same characteristics, despite one Arduino having been programmed and tested by Phil. The only unknown is the OLEDs - which were sourced separately but physically identical although those more informed than me can’t see any way it might affect these symptoms. It would be interesting to discover whether anyone else has built one from currently available components and how they got on. I believe 99% of us are using Chinese clones of Arduinos so there might be some differences from older versions? FF - thanks, it seems like the shielding on microwaves isn’t totally effective then…

I’ve gone with a vape battery - luckily my daughter is staying with us this week and had just finished one - what a waste, lasts a week or so but unrefillable apparently but with a 650 mAh LiPo cell and neat little USB C charger module, complete with LED charge state display. Unfortunately, I damaged the display during the excavation of the module which seemed to disable its charging function so went with a simple charge jack. While 2S would probably be better, it seems happy to work for several hours while maintaining sufficient voltage to function effectively and there are no balance charging considerations (although my ISDT charger gets a little excited by the prospect of doing an unbalanced charge!) I may modify the case design to incorporate a charger module and display once I’ve worked out its switching arrangement (some sort of suction operated switch in the discarded parts of the vape, but I don’t recall any wiring) - I’ve got my name down on the next vape!

Maybe a solution now but not really an explanation. It doesn't complete the boot sequence using a 2S Lipo - or a 2S LiFe for that matter but it does on a 1S Lipo with and without pull up resistors! I've left the new test assembly running in the kitchen for several minutes and it seems happy. I can see a couple of ways forward now but it does seem so odd that I've had these problems with the standard 9V power source. There seem to be two issues here - but are they related? First is the boot up - not a problem for anyone else and seemingly relating to the absence of pull up resistors to SCK and/or SDA. Second is freezing which seems to happen mostly, but not exclusively, in the kitchen where I'm seeing much reduced signal amplitude displayed when operating on the PP3. The only common factor which hasn't been eliminated - but one that doesn't seem to be considered a possible source of the problems - is that the display that I sourced from a separate supplier is physically identical to the first one. Worse in the kitchen...no, the microwave hasn't been in use while I've been testing but that does raise a separate concern...has anyone seen activity from one registering on the scanner or is mine leaking?

I don’t know if it helps but I knocked up a quick test assembly with my original Arduino and the new display. Guess what? It behaved almost the same and I’ve tried a Duracell on both too. I’m sure it’s wired as shown on the mode-zero site but in case I’ve suddenly developed colour blindness or electronic dyslexia, I’ve attached a photo of the test version and a video of it failing to initialise. A 10k pull up resistor to VDD got it further through the sequence but I didn’t bother trying to find the “magic” value(s) for this one. IMG_3997.mov P.S. I know the Duracell is out of date but it was still sealed...

I was referring to the direct board to board mounting method which I believe uses A6 linked to 0V and A7 bridged to 5V to feed power to the OLED. I’m using fresh Procell (industrial Duracell) PP3s and seeing a steady 5V at the 5V pin. On the first attempt, I established that it would work on any input voltage between 3.9 and 6 volts.

Weird, isn't it! I'll put another one together tomorrow with my "spare" bits. Could there be any difference connecting it via the spare pin method for direct mounting of the display on the Arduino - which way did you connect on test? Update - re the freezing problem, there does seem to be an environmental factor. In my living room, the scanner is showing a fair amount of 2.4 GHz activity (router and Bluetooth devices close by) and seems to run for extended periods but moving into my kitchen, where most of my testing has been done, signal levels drop dramatically and within a few seconds, the display freezes. However, the boot problem was occuring in the living room before I added the pull up resistors.

Got nowhere with the trial and error approach other than establishing that going much above or below 10k made it worse. A4 (SDA) seems to be the more critical pin to pull up in order to get it to complete the boot up. I'm wondering if a small 5v regulator to power it through the Arduino's USB connector would be the easiest solution.

Working from a couple of different devices for me. Maybe an ISP caching issue? Try a shift/refresh...

Hmmm....the saga continues now that I've put everything back together. While it now starts up and functions (almost) every time, the display locks up after a varying amount of time. It looks like I might have to continue experimenting with resistor values... One slight worry though - when my wife just turned on the (fairly new) microwave, it detected strong activity!

As soon as I hit enter on the post above, I had a thought based on some research I did a few days ago and Googled "Arduino pull up resistors" - which came back with a suggested value of 10k. With little to stop me and in the fine old spirit of "poke and hope", I did a temporary lash up based on Phil's earlier suggestion and lo and behold, it worked straight away! I'm not entirely sure about the function of these pull ups, which seem to be to better define 1 or 0 conditions and how this affects the working of the circuit but perhaps 1k resistors are now too low a value with the latest boards?

Well, I don't think it will come as a total surprise to Phil that connecting a new OLED made no difference! My replacement OLED didn't have anything connected to the C2 terminals either... The scanner works perfectly when connected to a 5v supply to the onboard USB port but despite measuring 5.08v at the 5v terminal when supplied by the PP3 it resolutely refuses to complete the boot sequence. Phil - can you recall whether you powered the board that you so kindly sent me from a PP3 while you were testing it? Scanner powered via on-board USB I'm wondering if anyone else has tried running this simple circuit while powered from other than the USB port? Perhaps something has been changed in the currently available Arduino boards? Anyone else here having a go at putting one together ? I see 8 people have downloaded my case design...

That's a fair point but on reflection it's probably more likely they put the tabs inboard on the trailing edge rather than on the ailerons to avoid all sorts of mass balance complications. Splitting the effect between the two wings would reduce the assault on the J60's aesthetics - perhaps a similar approach would make reduce Mike T's horror if you still have the model David?

I believe an upgoing trim tab like that will reduce tip stalling propensity but its interesting that the full size solution to correcting the effect of one twisted wing was to provide two inboard tabs.