Monthly Archives: February 2015

Building an F450 quadcopter – After the Build

flight_mapAfter our successful first flight it quickly became obvious that having a machine that can fly is just the beginning.  In the weeks that followed there were a number of change, crashes, and not an insignificant number of problems some of which are still not yet solved.

All of this occasionally has me wondering why I decided to build a quad copter instead of just plunking down money and to answer that we need to go back about 10 years to when I took my first tentative steps into the world of websites.  Back then I started a web small business with a friend and the venture lasted about two years before closing it’s doors.

Was I sad that the company closed?  No!  In those two years I had learned far more by doing than I could have learned in the same time at school, and the same applies here.

Each problem is a puzzle to be solved, an opportunity to learn and, as I have discovered, a great way to make new friends.  As I learn I like to give back to the community that helped me when I can and, as such, I plan to memorialize much of my learning here in small posts dealing with very specific subjects.  Much will not be of interest to people, but my hope is that one day someone will benefit from the time it took to put this together.

Pay it forward!

 

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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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