Gonna Fly Now... Maiden Flight of my SK450 Quadcopter

The day has finally arrived.  I have been waiting a long time for this moment.  Time to turn on the transmitter, plug in the battery and let my Quad take wings....   um... props  and fly.
I have tested, retested and tested again every possible thing I could test, check and confirm but now is the moment of truth.

The truth is, I think I am a little scared...  Scared for several reasons.  Will it actually fly?  Did I make some fatal mistake in the construction?  Was I wrong about the parts?  Would there be enough thrust to lift off?  Would there be too much thrust and the dang Quad will rocket off into the sky never to be seen again?  Will I be able to control it, since I have absolutely no Quad flying experience and very little helicopter or even RC plane experience?  All legitimate reasons to we a little nervous - and nervous I was.

So, time to head out to the back yard and give it a shot.  My other concern was my backyard has a bunch of bushes and buildings and trees so the only clear area I have is about 20 feet wide and about 10 feet deep.  Kind of tight for someone with no Quad flying experience.  The only good thing is the wind is very light.

Without further ado, here is the video of the maiden flight of my Quadcopter:

I do have to admit, this video was not the absolute first flight.  I did a number of short hops to check the configuration settings.  What I found out pretty quickly is that I needed to turn on Self Leveling or the Quads days were numbered.  So this video shows the first flight with the Self Leveling turned on.
My total flying time for all the hops was about 10 minutes, which I thought was great.  I had estimated my total flight time on a battery would only be about 6 minutes.

I was ecstatic, the dang thing flew and it actually flew pretty well, once I turned on Self Level.

For those of you that might be interested, my initial flights were using the default tuning values for the KK2 board under firmware version 1.5.

Roll & Pitch: P Gain=50 P Limit=100; I Gain=25 and I Limit=20
Yaw: P Gain=50 P Limit=20; I Gain=50 and I Limit=10
Self Level Settings: P Gain=100 P Limit=20 with ACC Trim Roll and Pitch both at 0

I had a very hard time controlling the Quad with Self Level turned off, it was just all over the place.  I suspect someone with good piloting skills would have had no trouble controlling it.  But with my "limited" Quad skills and my nervousness, I switched on the Self Level and was amazed how much easier it was to control.  I still had to make a lot of corrections with the sticks, but I could keep it in the air and in the same general location pretty easily.

All in all it was a very successful maiden flight.  I confirmed I had the right parts, put together properly so that even with my limited skills, I was able to fly the Quad. 

Next Post: Always Wear Protection (and other stuff).

Testing.... Testing...

Well, once again this post is not the post promised in the last post...  I think it is even better!!!

Today was testing day.  I was able to test all my motors, including Thrust tests.  I also did a preliminary test of the KK2 board.

Before I could do any testing I needed to make some cables for the Thrust Test Bench so that I could connect the ESC to the motor and the battery to the Test Bench.  I won't bore you with the details, other than, while I really like using the 4mm polarized banana plugs for connecting batteries, soldering them on is kind of frustrating.  The soldering part is easy, the problem is getting the metal part of the connector to snap into the plastic part of the connector.  If you get any solder on the outside of the metal barrel you will have a problem getting it back in the plastic connector shield.  Needless to say, I always manage to get solder on the outside of the connector.  So, then I have to get out a little file and try and remove the excess solder.  Not a lot of fun.

Anyway, I got a battery connector cable made for the Test Bench and also made up three wires with 3.5mm bullet connectors on one end so I could connect from my terminal strip to the motor.
This part was pretty easy, just solder on the connectors and put a piece of heat shrink over the exposed connector.  Easy Peasy as our Aussie friends say...

Below you will see a short video of a motor test, including Thrust measurements.  There is good news and bad news...  The good news - all the motors worked great.  The bad news...  They actually worked better than I had planned and gave me more thrust than estimated via eCalc.  I had expected about 600 grams of thrust at about 10 amps current draw.  I got that, but at about 70% throttle.  At full throttle, with a newly charged 3S battery I got 800 grams of thrust at 16 amps of current draw.
In subsequent tests I got about 760 grams at 15 amps since the battery was not fully charged.
This was bad news because the Electronic Speed Controls (ESCs) that I bought are rated at 18 amps and I am getting close to that rating at 16 amps.  I was hoping to have only about 10 amps at full throttle, which would have given my sufficient "head room" with an 18 amp ESC.  It's even "badder" news because currently Hobby King is out of bigger ESCs.  I would like to return the three unopened ESC and exchange them for 30 amp ESCs of the same brand, but they are completely out of stock.
Not sure what I will do now...

Here is the video I promised:

 

 

Here is the eCalc simulation estimates:

The other testing I did was plugging in the KK2 Flight Control Board to make sure it at least powers up and the buttons and sensors work.  That test went very well.  The KK2 board powered up as expected and I was able to move through all the menus and perform some preliminary sensor tests and configuration loads.  So, it appears the KK2 board it functioning A-OK.

So, lots of good news today.  Unfortunately I need to decide to go with the ESC's I have or wait until they get more in stock and then wait the 2 or 3 weeks to receive them from China.
At this point I am not sure what I will do...

Next Post:  Check back and see  :-)

Oops... this isn't Building the Thrust Test Bench

Sorry everyone, I decided to slip in this post today since I have to go to the hardware store and buy a hinge before I can build the Thrust Test Bench.

Just a quick little update on where I am...

I had ordered all the parts, well, not quite true.  I forgot to order an extra set of arms for the Quad frame in bright green color and also bright green props.  Both are for the front of the Quad to help in orientation.  The normal arms are white and the props black.

Here is what the replacement arms look like:

The props are the same color, so I should be able to tell the front from the back (hopefully) a little better.
I placed the order this morning from HobbyKing in HongKong and this order is coming International Air Mail rather than Air Parcel Post like my big order.  We'll see which arrives first.

I also noticed something while reviewing my original order...  It appears I might have ordered the wrong motors - well kind of wrong.  They appear to be sending the same motor but not the "short shaft" version.  The motor I wanted basically has no prop shaft sticking out of the motor.  You have to screw on a prop adapter to the motor bell housing and the prop goes on that.  The motor it appears they are sending (can't tell for sure) has a shaft, which will be in the way.  So, if I do get the "wrong" motor I will need to cut off the shaft with my Dremel tool.  I will need to come up with a good way to make sure none of the metal "saw dust" from the cutting gets into the motors.  Remember the motor are stuffed with powerful magnets so any metal filings will get pulled into the motor by the magnets.
My plan is to tape up the openings and then wrap the entire motor in aluminum foil before cutting.
Hopefully I will receive the correct motor, but just in case, I will be ready.

I promise the next post will be: Building the Thrust Test Bench

Designing a Thrust Test Bench

One of my "Buyer Remorse" concerns is that the ESCs I ordered (Turnigy Plush 18A) won't have enough capacity for the combination of motor (NTM 28-26 1200Kv) and prop (8X4.5) that I also ordered.
I have searched the Internet for others using similar configurations but found in almost all cases they used a larger ESC (usually 30A).  When checking the specs provided with the motor it would appear that the motor/prop combo will draw no more than 10 amps at full throttle, so my 18A ESC should be plenty big enough...  or will it???

So, the only way to know for sure, short of building the Quad and seeing if it fails, is to test the components and develop some data.  To do that the motor has to be running with the prop on.  You also need some way of determining how much current the ESC is being asked to control.  In addition, it would be nice to measure the thrust provided by the motor/prop combo to see if it (with it other three brother motors) will have enough thrust to fly the Quad.  Most Quad gurus say that you need twice as much thrust as the Quad weighs for successful flight.  Based on my calculation my Quad should weigh about 1,000 grams (about 2.2 lbs) AUW (All Up Weight, the weight of the craft with everything installed, including the battery).  So, if my Quad weighs 1,000 grams I would need thrust of about 2,000 grams for good flight.  Since I have four motors, each one needs to generate at least 500 grams of thrust.  Based on info I have found I am expecting my motors to generate about 700 grams - but until I can test it, I won't know for sure.

Based on the info above, my test bench needs to be able to meaure the following:

• Motor Thrust at full throttle
• Maximum Current consummed at full throttle
• Voltage at full throttle (to calculate watts)
• Temperature of ESC and Motor during and after run

The bench also need to be able to support the motor as it runs and allow unrestricted airflow both in front and in back of the prop as it runs.  In addition, the bench should allow easy connection of motor, ESC and battery.  The bench also needs some way to control the speed of the motor (a throttle).

I found a great video on YouTube from the boys at FliteTest. They build exactly the Thrust Test Bench I think I need.  I will be stealing their design, with a few changes of my own...

To build the Thrust Test Bench I will need the following:

• 2X2 and 2X4 lumber
• A Hinge
• Corner Brackets
• Scale that reads in grams
• Watt Meter
• Terminal Block (to make connecting the ESC easy)
• Battery Connector
• Motor wire connector (3) (short wires with 3.5mm barrel connectors for easy motor connection to Terminal Block
• Servo Tester (to act as throttle - won't need to use transmitter)

Good news is I have everything I need other than the Hinge.

Here is my CAD drawing:

Next Post: Building the Thrust Test Bench