Building an F450 quadcopter – Beware Idle Hands

 The first time I ordered something from China it was supposed to arrive in 2 to 4 weeks.  It took 7!

Aerosky

When I decided to build a quadcopter I found a kit on eBay that seemed just the ticket.  The price was good and the seller had great reviews but, unfortunately, they were in China.  Expecting the same delays I found myself nosing around various website the following weekend and came across a ready to fly H100 very similar to the one I was planning to build.

The controller wasn’t as fancy as our build (no GPS) but it down from the regular price of almost $500 to just $200.  

My mind got to reasoning this way.

  • The parts aren’t going to arrive for a quite a while, so if I buy this I’ll have something to fly until the other one is ready.
  • Having a pre-built one nearby will help with figuring out where things go.
  • I’ll be able to upgrade the controller and add a GPS later and can then either have two fully features quads or could sell one (perhaps even at a profit).
  • I had a little extra income which would more than cover the cost of this.
  • That price was so good…I’d be throwing money away if I didn’t buy one!

After putting it into and out of the shopping cart a few times, I finally pulled the trigger.  Since it was only coming from California it would arrive on Friday…the parts for the build arrived the Wednesday before!  

Not only that but the weather turned nasty bringing wind, ice and snow with the result that the maiden flight of this machine ended up occurring about 5 minutes before the maiden flight of the our build.

Thanks Mr. Murphy – you did it again!

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Doing the right thing…even when you’re scared!

When I was in second grade we lived in a little street in Plumstead, East London.  It was the sort of place where the houses were all joined together and everyone knew everyone else’s business.  For the most part everyone was in the same boat with little money to go around.

Across the street lived a chap named Clem.  Clem was one of the few people that we considered successful since he ran a construction business and owned both a van and a Jaguar when most people had neither.

Clem was well regarded and generally considered a decent sort. His wife was a permanent fixture hanging out of the upstairs window and surveying the street.  Nothing much escaped her eyes.

catapaultWith limited resources improvisation was the name of the game and one day I found a large piece of elastic and used it to fashion a simple catapult.  To say it wasn’t accurate was a huge understatement, but what it lacked in directional ability it more than made up for in power.  

I spent a happy few hours dropping stones into the little cup I had and flinging them up the street with gay abandon.

But then I pushed my luck a little too far with the size of one of the rocks.  It was a little large to fit in the cup and was quite a snug fit.  I figured with sufficient power it would easily fly out and, as I had done dozens for times before, aimed up the street and let fly.

Smashed-windowsUnfortunately in this case the rock did not immediately fly out, instead staying in the cup just long enough to fling around sideways and exit at a very acute angle, right into the side window of Clems van.  There was a pop and the window was immediately transformed into a million small fractures, rendering it almost opaque.  

I did what any self respecting 7 year old would do.  I ran!  I shot into our house, ran up to our bedroom at the back of the house and sat on my bed in a panic. What should I do?  Did anyone see me?  Could I get away with this?

Knowing that we didn’t have the kind of money available to repair a window like this I was sick with worry.

But, as I sat there, it slowly dawned on me what I had to do.  It took a while, probably 20 minutes or so, but I eventually found myself walking across the street and knocking on Clem’s door.

Clem answered and I slowly stammered out.  “I’m really sorry, but I was playing with my catapult and I broke your van window.”

I waited for the anger, the righteous indignation, and the demands for reparations that neither I nor my Mother had any means of paying.  In those days a good whooping wouldn’t have been out of the question either, and when my Mum found out I’d get the same from her.

Instead he just looked at me and said “I know.  Don’t worry about it.”  And, without another word, he went back inside and closed the door.  He never told my Mother and it was never mentioned again.  A few days later the window was repaired and life went on as though nothing had ever happened.

I often wonder what would have happened if I had not come forth.  Would the result have been the same?  Would I have been the same?  I don’t know, but I do know that i felt an enormous sense of relief and gratitude at how things turned out.

I never expressed my gratitude to Clem for the kindness he showed that day, so I’ll say it now.

Thank you Clem, you were a real gentleman.

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Building an F450 quadcopter – Maiden Flight!

We finally had a break in the weather long enough to get outside and get up in the air!

Before leaving there was some question about which two flight modes I should start with.  Key candidates were Stabilize, Altitude hold and Loiter.  I finally opted for the first two.  Stabilize because it doesn’t rely on anything fancy, and then Alt. hold to make flying a little easier.

The result?  In a word – awesome!  It’s been a while since I was able to fly and it was great to finally get back into the air.   See for yourself.

The F450 has some wobble to it.  Nothing terrible and it should be something we can fix using the Autotune feature of the APM.

S. loved it and wanted to try it out, but was too nervous.  That’s actually good as I would really like things 100% sorted before she does that.  But in the car on the way home she told me she wants a little quadcopter that is all her own :)

What a wonderful journey!

I’ve shared my parts list including links to where I bought things in case anyone is interested.  You can see those details here.

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Building an F450 Quadcopter – Day 7 – A very low first flight

Having seen one too many videos where the quad flips over on takeoff I was understandably nervous about trying our new baby out.  It seemed that at every turn there were little details that needed to be checked and re-checked.

For example, we checked the rotation of the motors and S. then fitted the props according to their direction.

APM RotationLater I noticed that we had the exact opposite of what was shown on the APM website.  Our props should have looked like this but were not. So, when S. wasn’t looking, I switched them.  

Fortunately I had woken up that morning with an idea that would allow the quad to fly a little, but not enough to flip over if things go wrong.  It didn’t take long before I had it lashed to our table tennis table and we were ready to try her out!

With S. videoing the first test was a spectacular non-event.  I powered up and slowly increased the throttle until full throttle was reached.  We had plenty of noise but absolutely no lift at all!  Then I realized.  S. had been right all along and I had switched the props which were now pushing it DOWN!

A quick switch of the props and we were back in business.  This is when I thanked my lucky stars that I didn’t trust myself to try it without a safety net.  Every time it lifted up it would go wild and try to flip over.  Fortunately the string kept it in place, but it was all over the place and none of the controls made any sense!  See for yourself!

I checked things over again and realized my mistake.  I had plugged the motors into the APM board with output 1 going to motor 1, output 2 going to motor 2 etc. in a clockwise pattern.  However, as you can see from the diagram above, the ONLY motor I got right was number 1!

Switching the connections on the flight controller had us finally up and running.  It now behaved, didn’t try to flip anymore, and I could lift it up and move it backwards, forwards, left and right.  Forward and backwards was reversed because for some reason the APM sets it up to expect the ELE control to be backwards.  No problem, it just took 30 seconds to change that on the transmitter.

While it seemed to be working it was very twitchy and super sensitive to the controls – nothing like my Phantom which was very docile.  

I posted the video on the quadcopters FB page and our good Samaritan made a comment about how twitchy it seemed. I then found out that the latest version of the Mission Planner software has a sliding scale from 1 to 100 where the higher the number the faster it responds.  Guess where mine was set…yup…100!  I backed that off to 80 which seems to have calmed things down nicely without taking all the fun out of it.

basicOne last thing.  Remember I said that my motors were the exact opposite of the picture on the APM website?  I was under the assumption that it didn’t matter as long as they the same rotation was on the opposite corners.  Turns out that is incorrect and that not having it the right way around is going to cause problems with yaw (spinning on its axis), and possibly more.  So, after some gentle teasing by my friends about not knowing how to fit props, I switched the bullet connectors so that they now all spin the right way.

After all those changes I put it back on the “test rig” and what a difference!  It was beautifully smooth and easy to control.  See for yourself.

So, that it is.  There are still many tweaks to do, such as setting up the battery failsafe and adding LED lights, but really the next big step is to wait for a clear day and take her out.  I can’t wait!!

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Building an F450 Quadcopter – Day 6 – Ready to Fly?

AssemblyFinally the weekend arrived and, with the new flight controller in hand, we could get to work.  S. was at a sleepover again so on Friday I performed the ESC calibration and confirmed that in all motors were finally working!

Unfortunately when I tried to run a normal flight test (minus the props) the double flashing red LED told me the pre-arm checks were failing.

I pondered the problem for a while and then realized the FC was in loiter mode which requires a GPS signal to work.  There’s not much GPS signal reaching my basement!  Switching it to “stabilize” mode had it firing up and we were finally ready to put everything together.

IMG_1544I waited for S. to arrive and we set to work.  She installed the anti-vibration plate, flight controller and radio receiver.  I put the GPS post together and she added the GPS to that.  The post had a little hinge on it and I couldn’t understand why, so when S. asked me which way it should go I told her it didn’t matter.  I figured out later that it allows for lowering the mast for transport.  By pure luck it turned out we had installed it correctly.

We had a hard time figuring out where to put the power module and it ended up awkwardly squeezed alongside the battery.  That might need to be moved if we decide to go for a larger battery in the future.

IMG_1556S. checked the motor rotation, installed the props and then, all too soon, it was ready to fly!  It wasn’t pretty but we were both over the moon with it.

S. had insisted that we set up my phone to record a time-lapse video, which I had to admit was fun to watch.  See below.

Not much to do now but give it a test flight, or so I thought.  With the conditions outside being 13f and 20-30mph winds it looked as though we would have to hold off for now.

To be honest I was nervous about this first flight.  I’ve seen a lot of videos where something small or silly caused the quad to flip and when it happens, it happens FAST!  

I went to bed worrying about that and, as is often the way, woke up with an idea on how to make that first flight almost foolproof!

Next post:  The first flight (why second guessing your daughter is a bad idea).

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Building an F450 Quadcopter – Day 5 – Flight Controller Test – FAILED!

After putting the frame together I figured it would be a good idea to bench test the flight controller, ESCs and motors before we actually attached them to the bird.  S wasn’t around so I had to do this sneakily, figuring I would then repeat the process for S once I knew what I was doing.

APM RotationIn theory all I needed to do was hook up the motors to the flight controller, connect to the power module and give it a whirl.  The first question was which way around the FC connector wires go, but a quick question and I confirmed that the white wire goes towards the middle of the FC.  I had the motor order from the APM website and I was ready to go.

I connected the battery, moved the stick to the bottom right which should arm the motors and…nothing!

After some fiddling (and some blind luck) I figured out that I had the throttle reversed on the transmitter.  This video helped me to sort that out.

Unfortunately I now had a bigger problem.  I could arm the motors but only 3 of the 4 would spin.  Motor number 1 (front right and connected to APM output #1) was NFG.

Back to those cool guys on Quadcopters who pointed out that I really needed to calibrate the ESCs.  Oh yes (doh!). Armed with the knowledge that I had missed a step I went back.  But, even after calibration, motor 1 failed to start.

Motor 1 happened to be the one that I had left the power cable connected (for backup) so I wondered if that was the problem.  I removed the wire without cutting it (this time), reassembled and…still nothing on motor 1.

Now we were in full on trouble shooting mode.  I tried starting things and wiggling wires and calibrating the ESCs individually.  Nothing worked.

Screenshot 2015-01-25 22.15.30There is a way that you can connect a computer to the APM and have it run a test on each of the motors.  To do that you need to connect to the “console”, but each time I connected to the console I ended up with spurious characters appearing on the screen and I couldn’t enter any commands.  I tried all of the methods people suggested to get around that and finally came across a post with a person who seemed to have a very similar problem. His problem was solved by replacing the APM flight controller!

I was now starting to think I had a hardware issue.  I tried one last test which was to switch the connections on the APM between motors 1 and 4.  When I started up this time motor 1 (previously not working) fired up fine and motor 4 (previously fine) was no longer working, thus indicating that output #1 on the APM is the culprit.

Since I was still within the 30 day money back guarantee (just) I started a return with the company I bought from on EBAY. I posted this on the FB Quadcopters group and one the most helpful people there – MG – who had been making suggestions and providing encouragement all along said that he would send me a spare APM that he happened to have to avoid the wait time involved in returns and re-shipping,!  No payment, wouldn’t even accept shipping.  Just said to try it out and we can work out what to do once things were up and running.  Amazing!

So, for a short time at least, the fun and games has to stop.  But not for too long – MG’s APM should be here in a couple of days, assuming the snow doesn’t get in the way.

I’m constantly humbled by the outpouring of advice and support the Quadcopters group has provided and only hope that one day I will learn enough to pay it forward.

Stay tuned…we will get this bird in the air yet!

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Building an F450 Quadcopter – Day 4 – Frame Assembly

My daughter was finally able to fit me into her schedule we had a date for 9:30am on Saturday.

We spent a little bit of time on Friday night trying to work out the best way to piece everything together.  To my surprise the APM 2.6 was too large to fit onto the PDB without sitting on the solder joints, and there was definitely no room for the damping plate.  

After much debate, and taking advice from the FB Quadtopers page, we finally decided there was no option but to switch places and put the battery inside and the APM on top.

IMG_1537

Satan’s torture device

First task of the day was assembly of the damping plate.

Let me just say, for the record, the person who came up with the idea of forcing those little squishy balls into those tiny holes on the plates is an agent of Satan.  Getting those things forced through 8 holes without tearing them took almost 45 minutes and included some serious tongue biting to avoid teaching S some bad habits.

IMG_1527

Frame assembly

While I was busy cursing the damping plate S. was busy attaching the frame spars to PDB and then flipping it over and starting on the top plate. Blue loctite was used to keep things secure but not permanent.

IMG_1538With that done it was time for us to attach the motors and secure the ESCs to the frame with zip ties.  Pushing in those little bullet connectors was tough, especially after the punishment my digits suffered putting the damping plate together.

IMG_1539Had I been more confident I would have cut the wires shorter before soldering to the PDB, which would have left less slack.  But with some zip ties we were able to make them secure, if not exactly pretty.

At this point we were ready to attach the flight controller, power module and battery and start configuring.  Getting to this point had taken us to 11:30.  I was all for pressing on but S said “No, I don’t want to finish it yet.  I’m enjoying building it with you”.  Awww!

We talked about what the next steps are and how the flight controller works with the ESCs to control the motors.  This was easy for her because we had built a robot with a Raspberry Pi, so she understands that the power cannot all flow through the computer.  We also took a look at the Turnigy 9X transmitter, which is very different from the Phantom one that she has used before.

9xNoting that the throttle doesn’t spring to the center she asked “How do we make it hover?”

This was a question that I didn’t have an answer for, but a quick look on the Arducopter site and know we know that in loiter or altitude hold mode the throttle just has to be within 40-60% range and it will hold altitude.

For once it is my calendar that is getting in the way.  I have a very busy week ahead and it doesn’t look likely that I will get around to doing anything significant until next weekend at the earliest.

If I’m lucky I will be able to bench test the motors before then.  I might have to sneakily do that before next weekend, as it would be nice to then do that again with S watching and know that it is going to work :)

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