CurryKitten's Mini Talon build

[CurryKitten]

With my bits of wire finally arriving, I set to work on a soldering night last night.  I extended the battery cable for my ESC, combined my power/video cables from the IRC 600mw VTX to a single servo cable so I could plug it straight into the Vector, and then I wired the BEC into the ESC wire, and finally took an old GoPro live out cable to use on the FireFly q6, and made that into a servo entension lead so I could power it from the ESC BEC... I think that was it.

Anyway, this morning (I do love not working Mondays) I first plugged the ESC in so I could check the motor direction (wrong, so fixed it) and then laid out all the electronics to test all my surfaces were working, and all the new cables were ok.  Everything seemed good



Next I started gluing... I really wish I had more than one set of hands here.  Although it felt like it went together very well, you'd get little tiny gaps opening up somewhere you wouldn't notice..  I was using my hands and feet at one stage - but taped everything up for a while while the glue went off.



Next I stuck the canopy on, and passed through all the cables - checked everything out again, all good.  So put the wings on for a test.



It's not quite done though, I need to put the reinforcement on the hatch cover, and put some sticks in the front so it will hold into the fuse (not that it's going anywhere, it's very tight).  I also realised I forgot to set the failsafe on my rx (schoolboy error)  Luckily, it's not deep in there, but will be a bit awkward to do.  I also noticed that my pitot tube is slightly crooked, which is annoying, but I don't think is a big issue.

Oh, and I've got to sort out where the CoG is and get some velcro in for my 4s 5200 multistar lipos and check the lipo cables reach the current sensor ok.  *Then* I can take it for a maiden and really hope for the best :)

I could do with ordering a new skew as well, I pinched this one off my Bixler, and I like all my stuff just ready to go without swapping bits around.

[FPVSteve]

Nice build Wayne,

Can I just emphasise getting the CoG correct because I find with mine if I have even the slightest hint of tail heaviness, it is VERY easy to tipstall on a launch. If in doubt, go for slightly nose-heavy. Don't want you to ruin the nose!!

Mine balances on the spars with very slight nose weight and it launches very nicely with a decent chuck.

[English Turbines]

 Looking good Mr Kitten....Have you remembered how to fly fast smooth planes..?
   
    Remember, you cant fly higher than 50mtrs....LOL......Hope the Maiden goes well anyway m8......:)

I must start gluing mine together, once I figure out this APM 2.8.....:)

:vulture:

[CurryKitten]

Cheers Steve - yep, bignose gave me a quite specific cog reference after his went wonky - so there's that.

I just need to get krikey on throwing duties for the first try

[Billy_boy_2010]

Pretty sure that's not super critical or anything.  It's lengthening the battery wires that causes more issues.

Really? Why would lengthening the battery wires cause issues? Assuming good solder contacts and suitable wire?? Interesting!

[Andy Sayle]

It increases the inductance on the input side of the esc. Because it essentially switching on and off (motor coils) very quickly, this can cause an excessive voltage ripple on the supply, and electronics don't like that.  The capacitor on the input side of the esc is there to smooth things out again thoughe.   The longer the escape wires,the more capacitance needed....

[English Turbines]

It increases the inductance on the input side of the esc. Because it essentially switching on and off (motor coils) very quickly, this can cause an excessive voltage ripple on the supply, and electronics don't like that.  The capacitor on the input side of the esc is there to smooth things out again thoughe.   The longer the escape wires,the more capacitance needed....

"Escape wires"...?.....Serious question though, I assume you mean we should keep the 3 cables from the ESC to the motor nice and short?

                                          :vulture:

[Andy Sayle]

Sorry, I was typing that on my phone, fat fingers and autocorrect.  It should have said ESC input wires (i.e. from the battery to ESC).

The capacitors fitted to ESCS can usually cope with a small increase in wire length, especially if you are running the ESC well under its spec.  As the current goes up, the voltage ripple will also go up, so must the input capacitance to keep control of the ripple to keep the sensitive electronics happy.

The output side of the ESC (i.e. motor to ESC) is not sensitive at all to wire length.  The output circuitry is designed to cope with a massive variance in inductance, due to the fact the the coils in various motors can range from silly low inductance, to crazy high inductance, depending on things like the KV rating of the motor.  So adding a bit of wire here, makes very little difference.  It helps to keep all three motor wires the same length, but I can't see why they wouldn't be!

That is why it is better to extend motor wires, instead of battery wires, in general.  Of course if you add extra capacitance to the ESC input, then extending battery wires is okay.  Also using a larger ESC and operating well under its limits, will help (as it already has a larger capacitance than required).

Posh ESCs (like the latest Castle Creations ones) actually have the ability to log the input voltage ripple.  It allows you to fine tune your ESC tuning, and also check whether your batteries are performing well amongst other things.

Hope that helps!
Andy

[CurryKitten]

Bah - typical, I was going to increase it at the output stage, but thought that was the one that was more likely to cause issues.

On the plus side, it's not a huge extension, and my ESC is over spec'd for the motor - so hopefully no issues, but I'll watch out for any !

[English Turbines]

Thanx Andy....well on the Mini Talon, I want the motor and ESC close together...I dont like having the ESC anywhere near my RX or FC...
   With the Lipo up front, having long feeder cables seems unavoidable......I have a fancy Heli ESC for mine, well overspec.....good job it is sounds like..

:vulture:

[Andy Sayle]

As a guide, I'm running a 50A esc (all I had at the time), at a maximum current of around 20 Amps, and I've had zero problems.  I have the motor and ESC at the back of my MT, with the esc pushed up against the motor mount.  The input wires have been extended to come to the Vector current sensor which is installed by the front spar/wing joiner tube thing.

It's one of them things that it is a case of trying it, and see how you go.  99% of the time, it won't be an issue.  The majority of ESC manufacturers will overspec the input Cap anyway.  Even if it is an issue, all you would need is a couple beefy electrolytic capacitors soldered in place at the ESC, so a simple fix.  I only learnt all this after building a contraption to demonstrate mechanical advantage, and torque.  Basically a long pole with a prop on the end, and a spinney office chair.  The battery leads were about 3 metres long, and I couldn't figure out why the ESC kept resetting itself.

If you do get an issue (and I really doubt you would in a Mini Talon), you will notice the input capacitor on the ESC getting hot, and the ESC may behave oddly, like randomly rebooting/reinitialising, or behaving erratically.

Cheers
Andy

[CurryKitten]

Because I'm a completionist, I just thought I'd do the last update on the build thread as I had just a few little bits to finish.  I made holes into the front of the fuse and then stuck some BBQ skewers into the hatch cover which then line up.  (also added a sticker :) )



Also on the hatch cover, to stop it from breaking, I glued in 3 bits of carbon fibre rod... which I had laying around from making a control rod for something else.  They aren't particularly straight, but I decided I didn't care



Then using the precision tool that is a sharpie marker, I sorted out the CG and drew a line where my 5200 4s Multistar lipo had to come up to.  I got the CG measurement from bignose, but it lines up just behind the spar, where the servo line channel goes around that corner.  I'm slightly nose heavy to start, so hoping for things to be ok.



Finally, and the biggest ball ache of the evening, was to set the failsafe that I'd forgotten to do.  My rx was attached far back into the fuse and the antennas were stuck through the top.  I managed to move some stuff just enough to be able to get a stick in there and press the failsafe button.  But now my rx isn't stuck on as straight as it was, and some servo cables aren't quite as tidy. *sigh*

It's now *properly* ready for a maiden.  I just need the right day, weather, and a chucker to help.

]

[Lola]

Looks very nice, good luck with the maiden.

[English Turbines]

Looking good Mr Kitten, very nice.

Have you got the L9R in there..?..Your going to need it methinks.

:vulture:

[Brucey]

Looking good Wayne. Good luck with the maiden