Power Switch

I've just completed installing the power switch between the battery and the ESC. This will make installing the battery much easier for one person -- just set the power switch to off and happily install without fear of shredded arms / legs from the rotor blades :-)



That being said, i have a slight nagging in the back of my mind about this particular switch. I assumed (i know, i know!) that because there were 2 wires for this switch, it was of the DPST variety (which is exactly what the doc ordered for this application), however when i applied my continuity tester just after soldering, i discovered it's actually only an SPST! -- that is, no matter the position of the switch (on / off), the continuity on the negative wire is never broken, only the positive wire is switched.

With a DC voltage, high amperage, brushed motors (inductive load -- unlike brushless motors) and now i also learn the switch is Single-Pole-Single-Throw... I'm a wee bit nervous, but hopefully it'll all be fine!

Many thanks to Monika for the 3rd and 4th hands during this work!

First Non-Crash Ending Flight!

I finally managed to completely use a fully charged lipo without one crash (i landed 3 times during that run all of them pretty good!). My flying control has improved quite a bit (i'm now just rubbish where before i was hopeless) recently and i have to attribute a lot of that to changing the way i hold the controls.

I had been flying with my thumbs on the tops of the sticks without even thinking about it. This method just comes naturally and seems the obvious way to hold the transmitter. Then i read a suggestion that holding the controls between thumb and forefinger results in better flying.

What i have noticed is this method encourages me to reduce the amount of control input i give and reduce the extent of that control when i give it. So when i reduce the amount of control i give the heli, it tends to hover more, rather than darting all over the place. It has all but eliminated my tendancy to over-correct.

I had been analysing the cause of each of my crashes and I had been attributing a lot of them to flying in too small a space, but now, i think for a lot of these the real root cause was my over-correcting.

Simple stuff, but it works. The only down side is holding the controller with my small fingers, balancing with my ring & middle fingers and controlling the sticks with thumb & forefingers is not a comfortable way to hold the controller. However, thanks to the SPAD (Simple Plastic Airplane Design) flying fraternity, we have a simple transmitter tray design to build which supports this method of controlling very well. And now i can't find a damned link to that transmitter tray i was impressed with! Oh well... at least this is something else to research.

How To Disassemble

I've been run off my feet with other things in the run up to Christmas, so not much heli flying time... though i still managed to squeeze some in: where there's a will, there's a way ;-)

Ok so my outstanding adjustments, each of which requires stripping the heli down:

• Tilt swashplates slightly forward to give a nose-high stance (in tandem with my earlier mixer adjustments).


• Increase the throw on the fore/aft controls


• Eliminate the need for very slight right-roll trim of the heli by levelling the swashplates port / starboard


• Install a power switch to ease turning on of the model

The steps i went through to strip the heli down were:

1. Remove rotor blades: these are simple, there's just the one screw & nut combo per blade. Obvious stuff.


2. Remove rear wheels: With a little tugging, these just pull straight out. If you're a bit ham fisted i'm fairly sure you could damage the lexan here, so be careful to pull straight out.


3. Remove the carbon-fibre bars between the front wheel post and the lexan sides: these just slide out, and it's not one long bar, it's two shorter bars, one each side of the front wheel post.


4. Pop the lexan shell with rubber grommits off the metal bars just below the swashplates. I found this tricky. The goal is to have the metal bars inside the lexan, so by squeezing your fingers inside the lexan from the top of the model, you can gently prise the rubber grommits off the steel bars one side at a time.


5. Manipulate the lexan up over the top of the model

Tada! at this point you have the lexan shell off, and one strange looking metal / plastic frame thing. All this is probably obvious to any seasoned rc heli flyer, but to me the beginner, it was all very much trial and error.

Screwdrivers

The screw which holds the flybar / balancing bar in place is tiny. I just didn't have a screwdriver small enough to take it out. Coupled with my local hobby shop's suspicion that this is not a screw of the self-tapping variety -- i resorted to ordering a good set online (local hobby shop can't source the ones he likes anymore).

I need to strip the heli down to make any of the adjustments i am planning (swashplate tweaking / installation of a power switch etc).

Which Screwdriver Set Is a Good One?

Cheap jeweller's screwdriver sets are 10-a-penny. They're cheap, but they're rarely made well and are more likely to grind away the delicate head on this screw than anything else. So what are my requirements for this screwdriver set?

• Recommendation from a fellow hobbyist: very important to me.


• Strong tips: very important to my heli :-)


• Good grips: It's frustrating not to be able to apply the necessary torque to a screw, a good grip helps solve this.


• Price: my local jeweller's shop will sell me very high quality screwdrivers (sold individually, not in a set) for £19.99 each!!! A set of 7 at that price would cost more than the heli!

The Candidates

1. Bost screwdriver set: This is what the local hobby shop use, however they can't source them, and i can't find the same set online (otherwise i'd link to it). It's a handle with interchangable heads of a good quality, all stored in a rigid plastic presentation box. Seems to be good, but difficult to source. Next!


2. Rolson 15pc Precision Screwdriver Set from Maplins. These are cheap enough (£10 in the maplins sale). However, these are made by Rolson, and my past experience of their cheap but nicely presented tools is terrible. I've been sucked in by their nice presentation boxes before and the tools are just cheap rubbish. Next!

At this point i felt i was struggling -- i don't know any other hobbyists to phone up and consult on this, and i can't find a screwdriver review online (ok so i'm not totally surprised by that last one, hence my attempt here!).

Known Good Manufacturers

So i resorted to thinking about tool manufacturers i have been happy with in the past, and one name sprang to mind from fiddling with the car: Draper.

Draper do a few ranges of tools, typically you will come across their budget offerings. A lot of these budget draper tools are perfectly serviceable and a great price. However, draper's budget line of jewellers screw drivers were clearly of the 10-a-penny variety and of no use.

The Draper Expert line is a different story. I've chosen to go for the Draper Expert 8 Piece Precision Screwdriver Set @ £9 from Abbey Power Tools.

These screwdrivers are excellent in my experience so far. I recommend them! I also recommend the Abbey Power Tools guys. I got to them via the Amazon.co.uk marketplace search. Their delivery was very prompt and their price was the most competitive for this set. Thumbs up.

First Crash!

Well i've had lots of little mishaps (including chewing the blade edges when the upper and lower blades flopped into each other's path!) during testing & tweaking, but this was my first proper crash.

I was losing control and the heli was flying backwards too fast. I dropped the throttle a bit much, and while i protected the blades (this time!), i managed to snap the front wheel of the under carriage. Very hard landing.

That was in the office, later on when i got home, i took the heli out the back to fly off the grass, but i managed to collide with the neighbour's fence and shred a few blades.

Total Damage

• 5 x Blades


• 1 x Front Wheel for the undercarriage

It would be good if it stopped there, but it doesn't! I decided to try to glue that broken wheel back on. While i couldn't get the wheel to stick, i did manage to glue the stump from the top of the broken wheel / leg into the post to which it locates.

The result was an unusable front post -- i can't plug a new front wheel into this heli now. Ok no problem. I have made a temporary fix for now while i wait for new under carriage (order placed with Ed tonight) and a new mounting post.

A £5 fix becomes £15 fix, but i learned my lesson: order spares before flying for less downtime! :-) Seriously, don't make half baked repair attempts. Think it through!

Tomorrow i visit a local model shop with it for some guidance on installing a switch for the battery. Hopefully No more awkward power-on for me!

Maiden Flight!

Woohoo! Finally, after lots of studying and some tweaking, it was time!

I had been doing small hops in the living room, progressing to short hovers as i tweaked each setting nearer the sweet spot. I felt pretty confident i was ready for a basic low level outdoors test flight.

I lifted it up to around 4ft and aimed for a steady hover. It became apparent that there was still some very slight giro tweaking required: when in hover the heli would tend to spin very slowly, very slightly counter clockwise. A little right-turn trim was a good "quick fix" for now.

I found the heli wanted to wander a bit, and given its size and the relatively small space in my back garden, it wasn't long before i had to do some beginner type stabbing at the controls (despite telling myself over and over "smoothly does it") to veer away from the fence and bring her down on the grass.

Success

Bumpy landing or no bumpy landing. I call that a success! It looks cracking in the air, and although the controls are a bit soft (i'll be addressing that soon) i was very pleased with the handling so far.

Next Steps

• Giro tweaking: very slight adjustments required to totally elimate the yaw


• Dis-assembly: I'll probably do this over the weekend. I plan to very slightly adjust the swashplates to give a very slight "nose high" stance, in the air and when taking off / landing. This is in tandem with my mix ratio twiddling earlier!


• While it's disassembled, i plan to adjust the hole on the bell crank arm that the the pitch rod (is that what it's called?) locates into, to give more responsive pitch control.

If any of the above ideas sound clever, i must stress they're not my own. I just learned of them from reading other folks posts!

Although tonight on the late shift i will be flying it about the office, just to get some more of a feel for the controls. I hope we're not busy tonight!

First Flight! & How To Fix All The Common Issues

I charged up the battery, bought some cells for the transmitter, then got ready to rumble in a big open space (the office at work ;-) )

Lesson 1: Transmitter on first!

I plugged in the battery pack and wham! Lesson 1 -- turn the transmitter on first, before the heli. Otherwise the blades will spin up and draw blood :-( My fault!

Ok, setup, powered on, ready to fly! Give it some throttle... and the top blades stop spinning! Argh! What's wrong with it?!

Lesson 2: Top Blades Stop Spinning

I was having the "top rotors don't spin" issue, until i read and understood that its not a problem at all. When the top rotors don't spin up, or they stop, it's normally because the #38 is still sitting on the ground and the gyro is getting a bit confused. Fix: shut off the throttle, wait for the blades to stop, then give it some welly the next time! Don't be a wimp! The top rotors will come back on as expected and they wont cut out in flight.

Lesson 3: Tighten the blades, don't spin the rotors just out of the box

Next problem was that when the top blades shut off, they flop into the path of the blades below. Ouch! The blades looked pretty nasty all chopped up like that after hitting each other (top and bottoms).

Fix: The blades have to be firm (not overtight either!) in the grips, not floppy as they are out of the box. Screwdriver and pliers, and i was all set.

Lesson 4: The First Real (i.e. not my fault) Problem

This was the hardest and the first *real* problem (the first 2 were just my lack of knowledge. The heli *really* wanted to spin counter-clockwise with any throttle at all. On top of that, the rear was lifting sooner than the front. That meant instant crash -- the rear lifts, the heli is left to balance on the front wheel, coupled with the powerful counter clockwise spin (you may experience clockwise, it's the same root cause!). Ouch. I have a new found love of grass btw.

I'll stop for a second just to say this is my first heli, i was feeling properly out of my depth at this point. Thanks to a post by Xrayted on RC Groups, i learned enough to tackle the issue.

Fix: there's 3 adjuster screws underneath -- extent, which i believe controls how far the servos turn (not needed for this issue); sensitivity, this is the gyro control, this is the thing causing the heli to spin; mix, this is the %age power for the front rotors vs. the rear, this is what's causing the rear to lift before the front.

The Mix Screw: Make the Front End lift Slightly Before the Rear

Twiddle with the mix screw first, it's the easiest to set properly. Set your yaw trim control to max in the opposite direction of your spin -- it wont be enough to stop the spin, but it will slow it enough to give you a chance to hop the heli up slightly to see if the front lifts first or the rear. I have it set so the front lifts a split second before the rear due to the tricycle under-carriage, for max stability. This has the downside that the heli will float backwards ever so slightly in hover (trim can handle it) so i might have to re-think.

These screws are very sensitive, you will be tweaking by no more than 1/30th of a turn!! Also, as many folks have posted, when you go past maximum, you're instantly back at minimum. Frustrating for me! But i got the hang eventually.

The Sensitivity (Gyro) Screw: Man this is hard work!

The sweet spot for sensitivity screw is a lot more elusive! But eventually i got it to the stage where i could control the spin by setting the trim controls. Stop at this point, you wont get any better!

Recentre The Controls, Stop Using Trim

Now turn off the heli. Turn off the remote. Centre each trim control (except throttle, which you should set to minimum). Turn on the controller, turn on the heli. Tada! No need to use trim! It's re-centred the controlls on the reboot, now you may just have the tiniest sensitivity screw tweaks to make to ensure no trim is needed at all. Reboot both units afterwards!

No Test Flight Just Yet...

All this took a while to research (remember i'm brand new to this) and some time to implement. Next post is the maiden flight!