Sunday, September 6, 2009

Epic fail on the X-240 diagnosis

OK so I it turns out I'm wrong about the remote being the source of the noise. After a big session of connection tracing in the remote today, I came to the conclusion that I could just de-solder the audio wires in the remote, and see what happens.

So after doing this, the hum/buzz was still there. Further tracing showed that there is a direct connection between the headphone socket and the subwoofer enclosure and this is not an audio cable. It is probably flipping a bit in an integrated circuit inside the amp which disables the pre-amp (and as a result my previous diagnosis of the amp still being turned on when the headphones are connected is wrong).

Anyway the status therefore is that the noise is being produced within the subwoofer enclosure, not the remote. This makes it a lot harder to fix because this is where the "brains" of the amp are and there are a lot of components which could cause the problem. I still believe it's a design fault or the quality of the components used to hit their price point, but it may be beyond my abilities. I'm going to leave it a few days and see if I get inspired to keep digging.

Oh, there isomething else discovered today: when turned "off" the speakers consume 6 watts of power, and when turned "on" they consume 7 watts. This is pretty poor for standby power consumption, and does not speak well for the environment friendliness of their circuitry. By comparison, my ancient set of Altec Lansing ACS45's (the original plastic-subby version) pulls 4 watts when "off" and 8 watts when on. That's a much nicer difference in consumption - and it even has an "auto off" feature.

Friday, September 4, 2009

X-240 architecture

Well I pulled apart the X-240 last night and - while I didn't fix the problem - I think I discovered the source.

So, the "remote" where the volume control lives is acting as the pre-amplifier (kinda, it's more that it's restricting the "volume" of the input source). Signals come from the PC here and a potentiometer (the volume control wheel) determines how much this signal is restricted - full volume I am assuming is "no reduction in input power" . It's also where the majority of the brains are located, including some additional circuitry which allows for the speakers to be shut down when headphones are connected. And most importantly, when this happens the hum goes away.

This "speakers turn off when headphones are connected" function interests me. It's not like power is being cut to the speakers, just the input source. If you put the speakers close to your ears you can hear a faint hiss, which shows that the power amp is still powering the speakers but is not amplifying any signal.

Further testing also showed that the headphone socket will work even when the speaker system has no power to it at all (even at the mains wall socket). This shows that the headphone connector is mechanically switching the audio input source from the PC sound card to the headphones. Only when the headphones are removed from this socket does the mechanical switch go back to passing the audio input source to the X-240 power amp, via the volume control potentiometer.

Therefore, my deduction is that the noise is coming from the circuitry in the remote. The power amp in the subwoofer box has filtering capacitors on it and shows - by itself - no external noise source. At the moment, I believe that the circuitry in the remote is the source of the noise, or there is noise coming up the power cable from the woofer box.

There are a number of ways I can try to test this, and my ideas at the moment are:
  • Solder in my own separate power lines between the subwoofer box and the remote
  • Hard-wire the power circuit and use the switch on the remote just for the audio connection
  • Hard-wire the audio connection between the PC, the potentiometer, and the output back to the power amp (bypassing the power switch)
  • Hard-wire the power, and also use my own potentiometer for volume control rather than the surface-mounted one in the remote.
Well, that's it so far. Now all I have to do is find some time to run the tests!

Wednesday, September 2, 2009

Logitech X-240 speakers, and humming.

This is way off the usual RC topic, but recently I purchased some Logitech X-240 2.1 speakers for my main PC in the study. They sound fine, but they hum like crazy as soon as the amp is switched on.

For those of you with the same speakers annoyed by the hum, allow me to let you know I'm about to pull this sucker apart and find the source. I've already had a peek inside the box by removing the subwoofer and I can see a very cheap job of cabling, and a separate AC-DC transformer. The transformer will be my first port of call, following by the amplifier circuit itself.

I may not fix it, but I haven't seen anyone else yet trying to fix their X-240. Sure it may well be because they're so cheap and folks feel like "they get what they pay for", but I've got a 10-year old Altec Lansing 2.1 system on my wife's PC which doesn't hum at all, and I recall paying a similar price. I am determined to track down and fix the hum, unlike Logitech who don't seem to care a whisker (the problem looks to be have been in the product for a long time).

Monday, July 13, 2009

Polishing a turd

As my experience with the RC crack habit has increased I've become a bit more cocky, and lately I decided to convert my old Aerobird Xtreme to stock electrics with a Spektrum AR500 receiver.

The basic process of conversion from those older style custom Hobbyzone electrics was pretty simple.

I went from this:

To this:

The new electrics allow me to use my main DX6i transmitter, which is a nice change from the stock Mode-1 thing that came with the 'bird. The flight characteristics are the same - that is to say that it handles like a pig and wants to crash a lot! Compared to my Radian, it really is a bucket of trash.

Anyway, I decided to continue the modding theme and use some of my spare servos to add ailerons to the wing. Top stuff, I thought. I immediately set to work, marking my aileron positions and servo positions on the wings with a permanent marker and a ruler, followed by cutting the ailerons from the wing and hinging them using tape. I hot glued the servos down to the underside of the wing after cutting a void in which they could sit, and carefully fitted the control horns and servo arms. All good, and nicely trimmed.

There is only one problem with the ailerons on the Aerobird. Quite simply, they do NOTHING!

First, I managed to launch off-axis from the wind and crashed, which caused the wing to snap since I had weakened the skin from where the ailerons were cut out. After glueing the wing back together and taping the weak points, I headed back out but only to find that after getting in the air I had no roll response from the ailerons. Getting back on the ground when I only had my rudders and elevators but now on different sticks was a challenge in itself, but as always altitude was my friend and I was able to spend the needed time focus and line up for a clean landing.

Obviously, things weren't working as planned. It turns out I made a range of classic mistakes:
  • The ailerons are WAY too small (5 inches each on a 55 inch wingspan)
  • It's an overhead wing aircraft with a very heavy low-slung center of mass
  • The wings have a huge dihedral to stabilise the flight characteristics
Is it any surprise that these points are going to make it hard to turn? I'm going to have to accept that performing rolls is out of the question, but if I can at least get her to turn using ailerons and elevator I'll be happy.

I will double the length of the ailerons and fit carbon rods to them for stiffness, but in the meantime I have mixed the aileron inputs to the rudder 100%, so that I can still control her using the right stick. Certainly before I did that today, my first attempt was very difficult as I was airborne with zero response from the ailerons, and I am not used to using separate hands for pitch and yaw.

I have most definitely put too much money into this little plastic plane. Even stock, the Aerobird had twitchy handling - it's designed to be stable but the wind causes it to roll even in slight breezes, and it tip-stalls easily. Spiral dives are an easy thing to happen and the small elevator throws make it difficult to get out of trouble.

Ultimately I really am polishing a turd. However, it's my first experience with 4-channel controls and I suppose that it's better for me to experiment and learn here with a plane I will be less devastated over if I bin it. I have soft-mounted the AR500 receiver, so if I can retrieve that at the least, I will happily put money into a Parkzone Corsair Plug N Play.

Thursday, June 25, 2009

Good batteries for a Spektrum DX6i

Those of you with a Spektrum DX6i transmitter will know that the LCD display constantly gives you a battery voltage reading, and that under 4.8 volts the transmitter will warn you about low voltage. What is annoying about this system is that while it's great to show you the voltage, battery consumption differs wildly between Alkaline and rechargeable batteries.

For example, you might feel great that your Alkaline batteries are reading 6 volts, but you can be surprised by how quickly the voltage drops as the battery discharges. In comparison, if you use rechargable Nickel-metal Hydride batteries, the charged voltage can often be less but the voltage reading doesn't necessarily change as greatly as the battery discharges. The DX6i voltage meter has to basically "split the difference" because it has no idea what kind of batteries you are using. And because of this, it errs on the side of caution.

My Spektrum DX6i came with a set of Nickel Metal Hydride (NiMH) batteries rated at 1.5 amp hours (1500mAh), and they were pretty crap with regards to holding a charge. Straight off the charger after a good three cycles of charge and discharge, they only ever show about 5.5 volts, which on the DX6i voltage display looks very close to the "too low" mark. And this can make you concerned. Certainly it makes *me* concerned, even when I may not need to be.

Enter the Low Self-Discharge NiMH battery. I went out today to pick up a set of rechargables and was about to grab a set of 2500mAh AA batteries when I saw a pack of what was called "pre-charged" NiMH batteries, of only 2100mAh capacity. I was curious - a pre-charged NiMH battery? How can that be - they're supposed to self-discharge when on the shelf! I ended up buying this pack, but shortly afterwards felt bad because maybe the extra 400mAh of the standard pack would come in handy.

When I checked Wikipedia (link above) for the details on these batteries though, I was surprised to read they are indeed a new type of battery, released onto the market in 2005. And have a look at the features which I ripped from Wikipedia:
  • Voltage is more stable (less load- and capacity-dependent).
  • Reduced heat buildup when the battery is quickly charged or discharged
  • Higher efficiency
Well Hello! Voltage is more stable, eh? That's great for my DX6i, because it means I won't see the lower voltages like 5.3 volts or so for a longer time. That is reassuring And I can charge the battery at or near 1C with less concern and less heat? That also is reassuring.

I discharged this battery pack today (4 AA batteries) down to 4.2 volts, and then charged it back up between .8 and 1.1 amps on my Thunder T6 charger in Delta-peak mode. When it finished, the pack read a comfortable 6.0 volts on the DX6i, which is very nice and quite similar to a fresh pack of Alkaline batteries.

If you wear an anorak, you might tell me at this point that I'm actually less safe because these new batteries have more of a voltage "cliff" where the voltage will not drop much until the batteries come close to being flat, before dropping suddenly. Well NUTS to you, sir: the voltage warning of the DX6i is 4.8 volts, which will give me plenty of time to land my plane, thanks.

All up, I thoroughly recommend these new low-self discharge NiMH batteries for your DX6i, DX5e or DX7. They are for sale nearly everywhere, and you can pick 'em by their "pre-charged" or "ready to use" branding and maximum capacity of about 2100mAh.

As always, cycle your batteries a few times (discharge and full charge) and be aware that some cells can be duds from the factory!

Wednesday, June 24, 2009

Teaching Dad how to fly

Being the RC Muppet, it is probably a bit cocky of me to think that I can teach someone how to fly given I only have a few hours of flight time myself. But what the hell, I mean, I'm the MUPPET so it would be out of character not to!

And this is exactly what I did last weekend with my father. We had both chipped in for a new Parkzone Radian sailplane and it came with a DX5e transmitter which I made a trainer cable for. Saturday afternoon had rolled around and Dad must have been keeping an eye on the weather forecasts, because he called me on the phone and I could tell he was keen. The conversation went something like this:

"Hey there"
"Hey Dad"
"What are you doing tomorrow?"
"Not much, why?"
"The weather looks good for flying, perhaps I should come round?"
"Hellz yeah!"

OK so maybe I don't use "hellz yeah" in general conversation but you get my drift. Before long it was Sunday morning and Dad had rolled up on his Bandit 1250, replete with backpack containing his DX5e. We didn't waste much time, grabbing both the Radian and my DX6i as well as my complete Mini Super Cub kit, and spare batteries for each.

I have to say I was initially nervous about getting Dad into the air but really excited too, because - aside from motorbikes - we haven't many chances to spend time together with a common purpose. Dad's a great guy, but he's not really into "just hanging around and shooting shit"; he needs to be actively engaged in something, preferrably complex and mechanical (or just riding his bike). RC planes turned out to be the perfect thing for us, because once I had gotten into it myself I remembered dad used to have an old glow plug motor in the shed he was going to fit into a scratch built plane one day (which he never got around to, but I still think he has the engine!). He saw my USB TX and simulator software and was so excited about it I bought him a set for his birthday. I actually don't think I've seen the raw excited side of Dad for a long time, so I knew he was going to be interested from that point on.

Well anyway, we hooked the DX5e up to my DX6i, turned on the plane and my radio (not the DX5e because it was the slave radio), and did some controls testing using my radio and then his radio while I held the trainer switch. Sure enough, all looked good. So we hit the skies and once I had some decent altitude I let dad go for it. This is where praise for the Radian comes in - it has really nice gentle handling and hangs in the air, giving you plenty of time to think. Unless you whack the throttle open, it won't get so fast that the plane is ahead of your brain - and I had planned ahead for that, getting Dad to keep only low throttle inputs.

Sure, he had the usual problems at first:
  • flying too close in and over his head
  • flying close to the sun and risking blinding himself
  • flying too fast for his level of skill and reaction time
  • flying too low and maneuvering too aggressively
But these were only small events quickly rectified by me releasing the trainer switch and taking control of the plane before we got into trouble. I think we kept this up for about 90 minutes and only two batteries (hey, it *is* a Sailplane you know!) before mental exhaustion got the better of Dad. At this point I whipped out the Mini Super Cub and had a short fly to give Dad a rest. I figured he was ready though, so I offered him complete control of the 'cub by himself, no buddy box.

Now, Dad's first attempt at flying were some weeks ago and with the super cub. They were less than stellar! Since I had mentioned the plane only has rudders he was trying to steer left-stick (we're mode 2), and I didn't realise it. He also was too low, and too aggressive on the controls and - even though the super cub has "Anti Crash Technology" he crashed nose down at full speed and snapped the nose off (which I repaired with hot glue and toothpicks).

But that was weeks ago. This day, dad picked up the radio and with throttle held, I hand launched the super cub for him into the wind and he flew really well. He was a little aggressicve on the controls at first, but only because the Radian has very soft handling and could even be called "laggy" on the rudder. The Super cub on the other hand has very fast handling responses and is best flown with a deft touch. It's not hard - it's actually a REALLY easy plane to fly - it's just quick handling.

Dad was flying so well, the only mistake he made was that he got cocky and decided to dogfight with a crow (they HATE my planes and they think where I fly is their airspace!). The crow bugged out, but not before Dad was low, fast, over a road, and into a spiral dive. He pulled out not in time to avoid crashing, but enough to avoid damage! Not that I really mind, the Super cub has taken a fair beating and keeps on tickin'. Heck, I snapped the wing in two and glued it back together with hot glue fer feck's sake!

All up it was a really great day and Dad earned his wings from me. Before he left to go home, he was already talking about a Spitfire ARF kit he had seen online.

Bug. Bitten. And don't I love it.

Friday, June 12, 2009

Using a DX5e and DX6i as a Buddy Box system

WARNING: Do not connect an older "DX6" to a DX6i, DX5e or DX7! It has twice the voltage and will do nasty things to your newer transmitters, like blow fuses!

The ParkZone Radian that me and my father just chipped in for together was an RTF kit, which included a Spektrum DX5e transmitter. I already have a DX6i, so the two of them together created a very powerful capability: the Trainer function.

All the new Spektrum 2.4Ghz gear (DX6i, DX5e and DX7) can be hooked up together to create a buddy box setup which allows one of you to be the master (active) transmitter, and the other to be the slave. Whichever plane the master transmitter is bound to can be controlled by the slave transmitter as long as the operator of the master transmitter is holding the "Trainer" spring-loaded switch.

It's very easy, and all you need is a trainer cable (and of course the two transmitters). "But wait!", I hear you say, "where do I get a trainer cable?". Well, you can buy an official one from JR or Spektrum, but nobody seems to advertise these and you can bet they will be overpriced. Save yourself the money and buy a simple mono "headphone" cable which is male at both ends, like so:

If you happen to only have a stereo cable, that will also work just as well. Alternatively, if you're a junk hoarder like me you only need to dig through all your cables until you find two cables which both have these small headphone jack ends on them, and then solder them together. The cable is "straight through", meaning that at both ends of the cable the wires connect to the same part of the headphone plug.

Spektrum recommends you don't use a cable longer than 15 feet. Personally I think the message should have been "don't use cables shorter than six feet!". If your cables are too short, one of the operators will spin around or do something else ham-fisted and end up yanking the other person's transmitter out of their hands. THIS WOULD BE BAD, especially if that was the master transmitter which was just tossed to the ground.

Anyway, once you have your cable, you just need to connect it to each transmitter (it's on the side of the DX5e, and the back of the DX6i). We're going to use the DX6i as the master here, as it has greater range of functions for servo mixing and the like.

You will notice as soon as you plug the trainer cable into either of the transmitters, they will switch themselves on. This is normal - your power switches on the front of the transmitters now define which one is the master and which is the slave, like so:

Note that the DX6i on the left has its power switch ON and the DX5e is OFF. This has set the DX6i as the master transmitter. From here on, the DX6i will operate as normal until the "trainer" switch is held. When held on, the sticks on the DX6i will not respond and all control inputs are taken from the Slave transmitter.

What's nice about this solution is that the "instructor" can hold that trainer switch until the trainee makes a dog's breakfast of flying. The instructor then can release the switch and have immediate control of the aircraft.

Now let us cover the critical things to do BEFORE YOU GO FLYING:

First, make sure all servo reversal switches on the slave match the settings on the master. If you don't do this, when the trainee takes over they will instantly turn the wrong way, dive rather than climb, and possibly go to full throttle when their stick is at idle. THIS WOULD BE BAD.

Next, TEST THE CONTROLS ON THE GROUND. Use the trainer switch to let the trainee take over and make sure their stick inputs make the control surfaces go the right way and that the throttle functions as expected.

Lastly, define that each person must set their control sticks in the failsafe position when not in control. THIS MEANS LEAVING THE THROTTLE AT IDLE! If you are the instructor and give control to the slave while leaving your throttle at 100%, then when the trainee gets ham fisted and you release the trainer switch you will accelerate into the ground at warp factor 10. THIS WOULD ALSO BE BAD. I recommend setting up some pre-agreed language for when instructing, like "instructor has control" and "slave has control", and to mentally associated those statements with the action of setting your throttle to zero when control is taken by the other person.

Thursday, June 11, 2009

Converting a Spektrum DX5e from Mode 1 to Mode 2

Hi folks,

I should probably first post that the reason I have a DX5e is that it came with my ParkZone Radian RTF kit. This thing is a beauty and if you check out the YouTube videos you might also fall in love. I'll post later about the Radian.

Anyway, since I live in Australia the DX5e 2.4Ghz transmitter came as Mode-1. I hate Mode 1, so I decided to convert it to Mode 2. It's so easy, even the muppet managed it!

First up, note that there are five switches on the front of your DX5e. Actually there are six switches, but the sixth one is covered up.

Once you remove the screws from the back of the case and pop the front off, you will notice the sixth switch on the right. It's labelled "JR_SW", and this sets the Mode between 1 and 2.

You have to flick that switch down to make your TX Mode-2, which tells the onboard computer which sticks are the throttle and elevators. Having set that, you lastly need to move the springs and throttle "clicker" from one stick to the other. It requires a small phillips head screwdriver, good lighting, and some patience. So, rather than bore you with the details you can watch my YouTube videos below which show how to do this to a similar device. Fundamentally the procedure is identical but some of the screws are in slightly different places. Don't worry, you'll get it!

Friday, June 5, 2009

First roll!


Now that I have that off my chest I should explain what it all means, Stimpy. Well, I achieved my first rolls today with my Mini Super Cub! Not bad for a plane with no ailerons, and I seemed to be able to consistently do it. I also was performing stall turns and a fair amount of loops, with a wee bit of flying inverted to boot. I do have to say though that I can't fly inverted for long as my eyes start telling me strange things and my fingers get all scared when I start thinking about turning while inverted. This is usually followed by immediately getting anxious about the whole thing and yanking back on the elevators.

Oddly enough, there was little or no wind today, unlike yesterday when I managed to snap a wing off during my lunchtime flying break. I've been bitten by this damned bug so bad I want to fly - and usually do - even when it would be really stupid to do so.

Thursday, June 4, 2009

Mmmm...shiny DX6i

My latest addition to my kit arrived on Monday - a new transmitter! It's a beautiful Spektrum DX6i, 6-channel 2.4ghz unit. And the total cost when delivered to my door was $294 from ModelFlight in South Australia. I love these guys, and will only buy somewhere else if they are out of stock.

People tell me I needed to have purchased a more expensive transmitter with like 7 channels or more. Bollocks to them! All I want to do is fly planes with ailerons and maybe have flaps and retractable landing gear. 6-channels does that just fine thankyouverymuch.

Anway, Spektrum make excellent kit and I just love the feel of it. However I can't use the darn thing yet because only my Aerobird can really be upgraded to stock electrics and I didn't have either an Electronic Speed Controller (read that as "a throttle for an electric motor"), nor any servos. The transmitter came with a very tidy little Spektrum AR6200 receiver.

This little receiver has two antennas, which you mount at 90 degrees to each other to increase the reliability of your signal. And they work up to three miles. MILES! Good Lord, about the most I fly away from myself is a hundred FEET!

Well to ensure I don't have a DX6i sitting on my desk for ages gathering dust, I picked up a 30-amp brushed ESC for $25 (the Aerobird has a 540 motor with a prop that only causes it to pull about 20 amps), and a a pack of six servos, also for $25. Sure they're cheap chinese servos with nylon gears, but I'm still starting out and my whole ethos at the moment is don't waste lots of money when you are just going to crash and need to spend it again.

Some of you will say I'm stupid and that maybe I wouldn't crash if I used expensive gear but I disagree with that. Most stuff that goes wrong at this level of experience is caused by the muppet at the transmitter, not dud gear. Give me about a year and then you'll see me bitching about stripping the gears out of my servos, but not before!

Mini Super Cub, and wind

Did you know that if you fly your Mini Super Cub in 15 mile an hour winds, you can snap the wing off?

Neither did I. But I do now!!! At first I was like "whoa check out how much the wings are bending!", and then when I landed (practically without moving forwards, the wind was so strong) and taxied up to my feet, the right-hand side of the wing just fell to the ground! It was a bit like that scene in The Blues Brothers, where after beating the shit out of their car for the entire movie, it gets them where they need to go and then completely falls apart.

But no matter. First, parts for Hobbyzone planes are very cheap (wings are like $14 AUD), but since she's made from that non-polystyrene Z-Foam I just held the wing in place and squeezed some hot glue into the gap where the wing snapped. A few minutes of holding position while the glue dried, and she was ready to go again. Since a lot of the wing strength comes from the thin skin that goes over the foam though - and obviously this was ripped - I added a couple of layers of clear packing tape over the break point, and also the left-hand side of the wing just in case.

I went back out to test it and sure enough she flys, but the wind was so much worse that I actually had a couple of cartwheel crashes from crosswind-induced flipovers. Ah well, there was no extra breakage so I'm still happy.

Monday, June 1, 2009

Don't fly into the sun!

I've just bought a new battery charger for my planes, and like the muppet that I am I managed to overcharge my NiMh 6-cell battery pack for my Aerobird Xtreme, causing it to vent. I had been inspecting the charging process every few minutes and it just so happened that I was standing there when I heard the telltale sounds of hydrogen venting. Not good, but after checking the voltage of one of the cells, I was happy that I hadn't destroyed any of the others thanks to that cell's voltage being exactly 1/6th of the total battery pack. But I thought I should go for a flight to check what run time I was able to get out of the battery, just as an test exercise (and possibly an excuse just to go flying!).

It was late in the afternoon before I managed to get out to my "field" (an unfinished new estate development with roads but no houses), and the sun was very low in the sky. I hand launched the Aerobird into the wind - not facing the sun at this point - and went to perform a circuit around me. Unfortunately, I then made the fatal mistake of getting my Aerobird between me and the full glare of the sun. And right at this point, the wind gusted and cause a bank to the left. By the time the plane was out of the sun glare, it was downwind from me, heading into a dive, and I couldn't tell what direction it was heading!

Now before I go on, I need to explain one of the biggest problems with the Aerobird Xtreme - it's shape! The tailboom, the V-tail, and the wing shape all combine to create a plane whose direction in relation to you is very difficult to determine. You can literally take your eye of this plane for a second and look back only to find your brain thinking "hang on it wasn't facing that way a second ago!".

So now that my Aerobird was banking and I couldn't tell what direction it was facing, I fed the wrong input to the rudder and only made the bank worse to the point where there was no more lift and a crash began. I reacted with up elevator and managed to initiate a recovery, but I still did not know which direction she was heading. And when the wings dipped again, I again reacted the wrong way. This time I was so low that she just nosed over into a dive and my up elevator only served to shallow out the angle with which she smacked into the ground.

There was only minor damage which was repairable - as is usually the case with the Aerobird - but it served as a reminder that all of my reaction skills are still concious efforts rather than unconscious muscle memory. And that means I still have a lot of learning to do.

Seeing as I was out there to test the battery capacity, I repaired the 'bird and went out again yesterday afternoon. This time, I avoided going anywhere near the sun and instead spent the time doing simple circuits and landing practice. Even during this, there were a few times where I just lost the mental image of the direction the plane was heading and had to override what my eyes were telling me with what my brain "knew" the plane was doing last. To say these moments are an intense mental battle is an understatement, and I am sure experienced RC pilots will attest to mastery of this battle as a critical skill needed for consistently safe flying.

Thursday, May 28, 2009

Just bought a new battery charger

I was doing my usual YouTube viewing of RC videos the other day and NightFlyyer had posted a review of a battery charger he had just purchased for $45 USD, a "Thunder AC6". This thing looked awesome, with fully computerised charging of NiCd, NiMH (up to 15 cells), Lead-acid, and all types of Lithium batteries, including cell-balancing up to 6 cells. It also discharges batteries for you, as well as charge your Lithiums to the right voltage for long-term storage.

Compared to the prices we are forced to suffer here in Australia this was an awesome deal so I decided to buy one myself from The unit Dave had was the AC-power model, but it seems that everyone else thinks these are awesome too so only the DC power unit model (the Thunder T6) was in stock. All up it was $76 USD including Priority International Mail which is still much cheaper than the "Swallow" charger available here from ModelFlight which is about $180 and doesn't even come with cables!

Anyway the charger arrived yesterday, and I have to say it's a full kit of stuff you need! The pack included all kinds of charging leads, the DC input lead with alligator clips, and even the temperature probe (which is usually an optional extra).

Probably the most interesting thing I have discovered about this charger is not its capabilities, but the fact that it's just one version of a number of chargers made in some factory in China. So far these are the chargers which are all fundamentally the same device in slightly different chassis:

  • Thunder AC6 and T6
  • Turnigy Accucell-6 (they also sell an 8-cell, 7 amp version)
  • Mystery charger
  • Imax B6
  • GT Power A6
  • Max E6
Now depending on who you ask - and their personal experiences - these chargers are either the best thing since sliced bread, or the biggest piece of crap ever built. There is certainly a number of people who have experienced failures (the Internet *loves* to point out failures and ignore success), but the biggest gripe seems to be a lack of accuracy in the charging process, especially when balancing LiPo cells. When I say "lack of accuracy", we're talking folks griping about .1 to .2 of a volt.

OK, I can see these people's point, but they're being pedantic! What about the el-cheapo chargers that come with the planes we buy? You don't see people shouting from the rooftops that these shouldn't be used, do you! Of course not, but they're probably just as cheap componentry - if not cheaper - than these cheap 6-cell balancing chargers. And I wouldn't be surprised if those came-with-the-plane chargers also have charging circuits which are only accurate to within .2 of a volt. So what.

I get really sick of people having a go at cheap kit, and basically saying nobody should buy it. BOLLOCKS. If these fools sat down for a second and actually engaged their brain, they might possibly have some common sense thoughts, like:
  • Is a $500 charger actually going to make a difference to battery longevity?
  • If it does, is the additional number of charges you get out of it going to be longer than before you toss the battery anyway, for other reasons?
Statistically, the answer is no, you muppets. This is market forces at its finest: some European or German company invents a charging system/circuit from scratch and has to recoup their costs. So, they make the circuit supremely accurate and charge an equivalent premium for it. Soon, some other company creates a less accurate but mass-market version of this technology and sells it for a third of the price. The difference in the products is a higher failure rate per 1,000 units manufactured, and the tolerances are less accurate in the circuitry.

Does this somehow mean that new product has no value or place in the market? No, it does not.

Friday, May 22, 2009

Busting my flying cherry!

The Easter weekend at our friends farm indeed proved the best place to learn to fly, with some great wide open spaces. Prior to this though, I did actually try to fly during the week previously. Near my house there is a large block of land slated for development as a school, which is where I eventually gave it a shot, but before I get into that I need to bear my soul for a second.

You see, I'm a bit shy. I also have a high sense of embarrassment and generally don't like calling attention to myself. Now picture yourself standing in the middle of a large empty field, surrounded by roads and houses with a large yellow plane in your hands: it is going to get people's attention! I was - and some days still am - torn between a huge desire to go out and fly because it's just so much fun, and the huge desire to avoid people seeing me make a mockery of myself. This battle of the mind went on for a few days, making me get more and more crotchety with myself, my family, my friends, and co-workers, until I'd had enough of myself and grabbed the Aerobird and went down to the empty lot.

Of course, I really had no idea what the hell I was doing, aside from having some flying skills shown by the simulator. Hands shaking, sunglasses on and my hat pulled down low over my eyes, I whipped the plane out of the car boot and strode onto the empty land. Without much fanfare, I picked the plane up started the motor on full speed and weakly tossed it into the wind. Immediately, it banked to the left, hit the ground, and shoved the rubber-band-mounted wing into the spinning propeller, taking chunks out of the foam wing. I repeated this process a couple more times before calling it a day and meekly hobbling back to the car with my tail between my legs. I didn't know it then, but the plane had a twisted tail which was acting as left-rudder input; ultimately it was lucky I didn't get airborne as I will soon describe.

So anyway, at our friends' farm at Easter, I managed to slip away from the house to a paddock behind the machine shed, out of view from most of the guests. My two boys, my brother in law, and the farmer's son (and his son too) all came to watch, and brought a video camera. Now this is where I would like to post a link to the YouTube video of what happened next, but for some reason nothing I did would let me copy the videos "of interest" off the camera. Maybe it was some kind of guardian angel protecting me from further embarassment... who knows?

I managed to get the plane airborne sure enough, but the first three attempts resulted in the following:
  1. Flipping into the ground as soon as I launched it
  2. Smashing the plane into the machinery shed at top speed
  3. Almost taking everyone's heads off
I mean, I launched it into the wind (a good thing) and had checked the trim, but because the tail was twisted it made the plane roll to the left and negated any possible trim inputs I could have made on the transmitter. At the time, I thought that the wing was off centre so I literally shifted the wing about an inch to the left to increase the lift on that side. Amazingly it worked, but probably shouldn't have! Once I finally was airborne I was flying quite well and having probably some of the best minutes of my life. In those short moments I had confirmed that all my impressions on how much fun it was were correct! Fun, just pure unadulterated fun, which is exactly what it is supposed to be.

After a few minutes of flying around I managed a neat landing and was quite chuffed with myself. So that I didn't spoil the moment, I decide that would do me for the day and put everything away. But trouble was brewing, and little did I know it but the poor Aerobird was quite severely damaged internally...

...and the next morning before everyone was up and about, I decided to have quiet little flight. As you probably guessed it did not turn out well; as soon as the plane was airborne, I couldn't control it! And with no trained emergency response, I reacted badly and ended up very high in the air, getting far away from me and headed for a road. Finally I chopped the throttle shut and nosed the plane over into a hard dive, straight for the ground. The impact didn't look bad but after I arrived I discovered that I had overflown some three phase power lines, missing them by a bee's whisker, and then crashed in a ditch between those power lines and the main country road. I was very, very lucky to not have caused more serious problems either to road users or the power grid!

Once again with my tail between my legs, I collected my broken plane and went to inspect the damage. I had split the fuselage and broken off the rubber nose cone, but worse I discovered that the cause of this crash was instigated by the previous days' impacts. Unknown to me at the time, I had yesterday cracked the circuit board which mounted the servos that control the tail, and it had finally broken whilst I was in the air this very morning. Due to the tail control surfaces being held by a rubber band (to put force on the fishing line control wires), the elastic force pulled the elevators down, and the circuit board inside the Aerobird was backwards. With the circuit board loose the servos could not pull the elevators up and so I had no up elevator control or ability to turn, which explained the crash! If only I had cut the throttle earlier I could have avoided coming so close to power lines.

There was good that came out of this crash though; the damage forced me to sit down with the plane and become introspective whilst repairing the plane. It was here that I discovered the tail was twisted, and also learned about how to properly adjust the trim of the control services using the control horns. Ultimately, I needed to crash to force myself to learn these facts and it was much better to do this on somebody's farm paddock than in an empty lot surrounded by houses in Suburbia!

And you know what? The rest of the day I had many successful flights with some beautiful landings. Only one crash happened that day and that was when I let my brother in law fly it, when he had zero experience. He did quite well and the newly-fixed control surfaces allowed for a much more graceful impact with the ground.

All up, I had managed to learn to fly, and I did it without destroying the plane thanks to its toughness. Sure it was basically held together now by gaffer tape and super glue, but it was still airworthy. And as they say, any crash you can walk away from is a good one. I think the analogy still works here.

Starting with a simulator

While sniffing around the Internet, I found that folks sell USB RC radios - you can't use them for real but they function as a joystick, albeit in the shape of an RC transmitter. And not only that but there are heaps of RC flight simulators on the market, ranging from free up to many hundreds of dollars!

I did my research and discovered that there are two schools of thought for your radio controller: Mode-1, and Mode-2. Mode-2 is where your elevators and ailerons are on the right-hand stick and your throttle is on the left, along with your rudders. Just like a real plane, oddly enough. I've also been flying flight sims on my PC for years, whether they be just a simulator, or a combat simulator like Falcon 4.0, and used the right-hand stick, left-hand throttle and rudders layout with my funky Thrustmaster joysticks. So naturally Mode-2 suited me just fine and all the folks in the USA use this, but there is a snag when you're an Aussie.

In Australia, the majority of folks fly "Mode-1". Mode-1 is where your throttle and ailerons are on the right-stick, and your elevators and rudder are on the left. And worse, it's a religious debate on what Mode is the best. Lots of people were telling me to fly Mode-1, because nobody would teach me how to fly using Mode-2. And did I already mention how I HATE RULES THAT EXIST FOR STUPID REASONS?

The arguments about why Mode-1 is so freaking awesome just pushed all my buttons. Reasons like "because you might accidentally get aileron input when you use the elevators" are rubbish. You like Mode-1, great - but please don't push your opinion onto people who like it different. People who look down on you for using Mode-2 can take their attitude and get lost!

So yeah, "feck the status quo" was my motto and I stuck with my plan to fly Mode-2 (and I haven't looked back either).

I was excited, but also feeling justified by buying the simulator kit; if I found that I couldn't fly worth a damn, I would only have wasted about seventy bucks ($30 for the USB "transmitter" and another $35 for the flight simulator). The simulator software is brilliant, because it simulates you standing on the ground in one spot and looking up at your plane flying around you, just like in real life.

Unfortunately for my bank account, it turned out I could fly quite well. Which only made me want a real plane even more!

For anyone who is interested, the USB "radio" I purchased was the E-Sky simulator kit which included the free "FMS" simulator, and the simulator software I later purchased is ClearView.

My first plane

A few weeks after I had my simulator and being hooked on watching all the YouTube videos by folks like RCSuperPowers and NightFlyyer, I mentioned my new obsession in passing to a senior co-worker at the office. It turned out that he is also into RC - but only helicopters now - and that he had an old plane lying around which he didn't want anymore and had only flown six times.

To say that I jumped at the opportunity to acquire this plane is an understatment. I had no idea what it was of course - and I didn't care. I had to wait though, as me and the family were heading off to Tasmania for a week. I would say the wait was hellish, but I do actually like spending time with my wife & kids. So anyway when we were back home later that week I dropped around to my co-workers' place to pick up the plane.

It was not what I expected, to say the least! I had an image of a light, foam-bodied plane in mind, but what I got was a large, 55-inch wingspan Aerobird Xtreme, with a fibreglass tail boom and a V-tail, activated by a combination of fishing wire and rubber bands! The thing is huge, and very imposing. I was immediately scared to the fly it too, since it came with a Mode-1 radio that has a slider throttle on the back of the radio.

My co-worker had been advised by folks at his local club that it was a good plane to learn on. "Teh Interwebs" disagreed - most folks said it was a great plane, but not good for a learner. Again I figured they were full of it, but as time has worn on I can see why they were right. I am being completely truthful when I say that you want you first plane to be light, easy to handle, but also to have fast responses to control inputs. Let's see - the Aerobird Xtreme is heavy (with a big 6-cell Ni-Cd or Ni-Mh battery), handles slowly (great!), but has slow response to control inputs, so when you get close to crashing, it's hard to recover.

I took this plane down to the local club, looking for help with getting flying. The interest in helping me was there, but the enthusiam to do so was definitely low. Most folks saw this as a "toy" and nothing more, because it was electric. Once again, my enthusiasm for flying was beginning to be curbed by a bunch of too-serious close-to-retirement old buggers whose opinion was the only correct one. In the end I left feeling a bit dejected, because I was really keen to see the plane fly and be helped out. Since the result was basically "come back later", it just made me feel like when I was a kid - regimented rules on when stuff can be done, dictated by someone else.

I also wasn't impressed with the responses from the club members on how to get into the sport. "Minimum $600 to get started" was common. Oh really? A Hobbyzone Mini Super Cub will be delivered to your door in Australia for less than $200 - including radio, battery, charger, and everything. Please explain how this is somehow NOT an acceptable means of getting into the hobby? It was more narrow-minded, blinkers-on bollocks!

The weekend after my trip to the club was Easter, and our family traditionally travels to a friend's farm out near Maffra in Victoria (Bushy Park to be exact), and they have a few hundred acres to play on. I did some more Internet research and discovered that according to the CASA regulations (Part 101) you don't have to fly at model clubs; as long as you maintain good distance from houses and people, stay below 400 feet, and don't go within three miles of an airfield for real planes, you're good to go. So before we left, I packed the Aerobird into the car and planned to bust my flying cherry over the Easter weekend.

I wish I'd set up the blog when I first started flying.

So, this is a blog of me and my rapidly-developing obsession with model aeroplanes.

You know model aeroplanes - the flying kind. Not the kind you spend weeks painting and stick on a shelf, only to fill it full of gunpowder and see if you can turn it into a rocket. Hmm, did I just give away some of my childhood there?

Anyways, about three months ago I was putting my four year old son to bed and we were watching YouTube. Jet Fighter crashes and ejections, specifically - he thinks those are really cool (and hey, so do I). The usual Wikipedia effect happened and before I knew it, I had followed a trail of videos after my son was asleep which led to some stuff posted by a bloke named Dave Powers, otherwise known as RCSuperPowers, and he was having heaps of fun with RC planes.

Allow me to dig back into the past for a sec...
Now when I was a kid, I thought RC planes were very cool. My neighbour was a good mate of mine (hi to Marty Cooperwaite) and his dad was into RC planes *and* helicopters. This was the 1980s too folks, so it was scratch-build terrority and big dollars to get flying. I went to the local flying club with them a few times, but it all seemed quite rigid with rules and with some very serious people - maybe rightly given the costs if you crashed your balsa-framed beauty. It still put me right off though, because I'm all about fun, and I've always hated "thou shalt do it this way" garbage.

I guess it didn't help that I had no spare cash, consistently had no spare cash until I had been in the workforce for 6 years, and also happen to be a computer geek first (guess where the majority of my spare cash still goes). But I have digressed too far, so let me get back to the present day.

So there I am, watching Dave Powers on YouTube, and this guy is having a blast. He's out in the local park with his electric planes he builds out of foam (or testing planes from other RC merchants) and talking about how the planes work and how to fly, and the guy is really cool. His wife Val does all the video work and she's also really into it and having a laugh.

All I can think is "wow, maybe this can be fun after all". It doesn't hurt that I've got a more spare cash these days and people sell Ready To Fly (RTF) planes, including batteries, radio transmitters, the lot. And even under $250 - in Australia!

At that point, I found myself watching RC YouTube videos whenever I could. I knew I was hooked and that it would only be a matter of time before I actually did something about getting my own plane. That was three months ago, and I already now have TWO planes and want more. Finances will slow down the rate of acquisition certainly...