Monday, July 29, 2013

A Couple of Pictures from COSMOS

 Unbeknownst to this blog, the charming Mrs. EastBay RC carried a camera outside when we went flying and took a couple of pictures.

Here's the Arcticopter VI failing to arm.  I took the chance to explain that lots of technical work consists of standing around looking befuddled and troubleshooting on the fly.  They seemed to appreciate that, having apparently experienced the same thing on their own projects.
 The NutBall never fails to please.  It was nicely visible in the sunshine, and handled the small flying area pretty nicely.  I did take the opportunity to have the wind blow it into a tree, though.  I got some laughs when explaining that I had been going for a patriotic USA paint job only to have it turn into a lovely French scheme.  Many thanks to piloting assistant Sandra for impeccable launch form!
I was pretty impressed with the COSMOS attendees I met.  They seemed smart and motivated, and are working on some interesting projects.  Perhaps the future is in good hands after all!

Sunday, July 28, 2013

One Minute Guide to DX6i Binding

Here's how to bind a Spektrum DX6i to a receiver.
  • Tx power off
  • Insert bind plug into Rx bind port.  Polarity doesn't matter
  • (optional) Plug a servo into Rx AIL channel.  Not necessary, but you can use it to see if your binding worked.
  • Insert ESC plug into any RX channel.  Doesn't matter which one, since we're only concerned about power.
  • Rx LED will fast blink.
  • Move Tx about 5-6 feet away from Rx
  • Pull up Tx Trainer switch.  Turn on Tx.  Screen will show "Bind"; Keep holding Trainer switch
  • Rx LED will: stop flashing; resume slow flashing; stop flashing;  Wait a couple more seconds.
  • If you have a servo plugged in, it will come to life.  Test by moving AIL channel.
  • Release Trainer switch.
  • Power off Tx, Rx, remove bind plug.
Two biggest problems:

  • Tx and Rx are too close.
  • You don't hold the Trainer switch for enough time.

Friday, July 26, 2013

Great Amazon Metric Fastener Pages

Found some great pages at Amazon that let you select various sizes of fasteners.  I called Amazon to see if there was a way to locate all pages with these awesome selection menus, but it seems there's not.  If anybody knows a way, please leave a note!

Till then, just recording these:  machine screws, pan head screws, steel hex nuts,

Thursday, July 25, 2013

Taranis Quick Unboxing and Overview

Well the much-awaited Taranis arrived, and here's a quick unboxing and overview.  I hate long unboxings, so this one is pretty quick.  I'm going to do new versions of my er9x videos and posting (which have received lots of nice comments, thank you all very much!)

Most important bit: there's a bolt and washer sitting loose in the foam padding, so be careful to retrieve them before they get lost.

In case you want to see the er9x mixing videos (which apply about 99% to the Taranis as well), they are here:

Wednesday, July 24, 2013

Are your 18650 Li-ion Batteries Fake?

 TaoBao has some hints here.  I've copied the pictures below and translated the Chinese text. ht: ahvttvsn.

Note the 2D Bar Code.  I think the white text identifies the manufacturer.

Looks good on the outside, but look more carefully.

The outside code is super-thin and elastic.
 Take off the covering and look on the inside.
 Quality of body and cap is matched perfectly.  It is not done by a counterfeiter.

Bare ("naked") cell diagram.
 Counterfeit vs. Genuine.

Counterfeit is only plated on top and has dull body.
Genuine is consistently shiny.

Note the reflection on fake and real.
There's more information on the vendor's page.  There's a chart showing the lousy power output of the fakes.

Vibration Dampening Grommets

I saw a jabrams @ rcgroups post where he mentioned the vibration dampeners he's using.

He got them from element14.  Note you need two pieces.  Read the post for more details.

GEL MEC - GVD-1010-40
Manufacturer: GEL MEC
Order Code: 1422144

Manufacturer: GEL MEC
Order Code: 1422159

PX4 Ar.Drone Settings

If you just install the raw PX4 board, you will discover that all PID coefficients are zero.  Here's the well-hidden location showing the necessary settings.  Tuning notes here.

Sunday, July 21, 2013

Motor Thrust Measurement

 I'm starting on a project to measure some motor/prop/battery combos, so I took the chance to update my thrust jig to hold some bigger props.
 There's a cutout where the motor mount attach so that I can use M3 25mm bolts.  Most of the motor mounts are sized for M3, and 25mm are the longest M3 bolts I've got handy. It's still plenty strong.
 Be sure and clamp the entire thing securely to your bench so it doesn't fly off right into your face!  If there's any vibration, this unfortunately magnifies the noise.  I'm going to try putting some padding underneath to quiet everything down.

(update below on the L-bracket connection.)
 I had some crossbars screwed onto the motor cutout as a reminder not to put my fingers near the prop line.  They added to some vibration, so I took them off.  The thing is loud enough that there's no doubt where you should not be putting your fingers.

You only need to spin the props up for a few seconds to take the thrust reading.  You can then shut down and then read the values off the watt meter.
 Here's the electronics.  There's a watt meter in the power circuit, and a servo tester to control the motor speed.  After running the initial tests I finally got around to swapping out the Deans connectors to XT-60s.
 The watt meter nicely has a hold function to measure the peak power use.  Unfortunately, the scales don't have such a feature, so you have to keep your eye on the max value there.
It occurred to me that it's a good idea to put a monitor on the battery to beep when the battery starts going low.  I taped up the speaker to quiet it down.

Update: it's working pretty well, with the exception of excess vibration when spinning big props at high speed.  That's because when I drilled the mounting hole for the L-swing I left a tiny bit of clearance so the thrust would transfer smoothly to the scale, but that introduces slop which induces vibrations at high thrust. I've got some 4x10 bearings ordered which will hopefully smooth things up.

Here's the unit in action:

Quick and Dirty Spray Booth

Friend and fellow Concord Model Engineer Warren Delane reports a clever idea for an outdoor spray booth:

Thanks to Richmond Sanitary, their paper-only recycling bin is perfect... The bin screens out breezes when I spray outdoors (you do spray out of your workshop, don't you?). There are indents that can support the wing tips of a 28" w/s model like this Sig 'Shoestring' C/L .15 class racer. Two coats of spray Gloss Lemon Rustoleum, $3.77 at Wal-Mart. Bought 'Shoestring' kit and engine at Alameda Swap Meet for only $20. Such a deal!"

Friday, July 19, 2013

Great Time at the COSMOS Program!

I had a great time speaking at the COSMOS program at U.C. Davis this week.  Gave a talk about the work we're doing here at EastBay RC, showed them lots of models, flew (indoors) the Ladybird and Vapor and (outside) the Nutball.  Had a hands-on demo in applied glitchery when the Tx wouldn't bind to the Arcticopter.  Met some great students... smart and enthusiastic!

It's a neat program... if you're a high school student it's definitely worth checking out.

Pool Noodle Blade Guards

It's summertime, and that means cheap pool noodles at the store! In honor of the terrible, horrific, scary posting at diydrones about prop injuries, here's a method a lot of people use when working on their quads.
Slice out a section, and it will fit nicely over your props.  If you accidentally power them up, they'll shake and shudder alarmingly in the noodle, giving you plenty of time to pull the plug.

See it shimmy and shake in the most shocking manner!

Monday, July 15, 2013

EastBay RC Distinguished Lecture at U.C. Davis

As part of the COSMOS 2013 Distinguished Lecture series at U.C. Davis, I'll be presenting "Homemade Drones: The DIY Revolution in Aerial Robotics".

Synopsis: "This talk will be about hobbyist drones. We'll talk about how they are made, the interesting technological innovations that make them possible, and how you can build your own. I'll bring a couple of homemade drones (both multirotor and fixed wing) for you to examine. Conditions permitting, we'll take them out for a flight following the talk."

July 31, 2013, 1:00 - 1:50 p.m.
UC Davis Conference Center, Ballroom A, B, C

If you're in the area stop by and say hello!

Sunday, July 14, 2013

Nice Blue Wonder Motor Mod

The always awesome joseico90 at rcgroups has a nice tip for easily improving the efficiency of a blue wonder motor.

with this mod to improve cooling I'm managing 11Amps for 20 secs periods doing the odd hover 
Blue wonder 1300KVAbout 110 watts on 3s 460's packsAnd the biggest slow prop I could, a GWS 10x4.7 
I love this set up for slow aerobatics on my 30" Big Blue

Wednesday, July 10, 2013

Concord Model Engineers, Minutes for July 9, 2013

CALL TO ORDER:  7:38 pm


Ed Ringue started building planes a couple of months ago. He's mainly interested in freeflight.

Steve, started with control line, interested in control line.


    Current Balance                 $4,980


Minutes on iphone and therefore not read, but approved anyways.

Tuesday, July 9, 2013

Motor Mounts: First Try

 Here's the first run of the motor mounts I've been fiddling with on the 3D Printer. I had to drill the holes out on the drill press using a 1/8'' bit, which is 3.175mm.
 The pieces hold on to the 10mm square fiberglass arm splendidly.  The friction fit is snug.  I don't think it will take much bolt tension to hold everything together nicely.
Need to extend the width of the mounts so there is more material surrounding the hole.  As expected, the bolts don't need to be tightened up much.  Final assembly should be with nylock bolts, or using threadlock.  Tighten them in opposing pairs or you will star to pull the mounts around the stick, stretching the holding arms apart. Black looks cool, should get some black bolts too.
 Just clearing the motor shaft.  Everything spins freely.  Maybe open up the hole a bit more so the entire circular part of the motor is exposed?

Need to extend the length of the mount.  Note that the bolt holes are covered by the motor.  I think instead of a single mount that holds multiple motor sized, it will be fine to have a couple of mounts customized for different sizes.
Need to get the countersinking right.  It seems to work even with the bad countersink, but I'm a bit concerned that the motor bolts will cause some stress on the relatively thin wall of the arm and it will crack when the motor gets some stress applied to it.

To Do:

  • make a couple of parameterized files, one for each mount size. parms: motor bolt length, overall length, bolt size.
  • fix bolt holes so they don't need to be drilled out.
  • fix countersink.
  • add LED holder? (one? three across on outside?)
  • extend material around clamp bolts.

Monday, July 8, 2013

The Fleet: Noodle Copter

Here's another one for Crash, as he's exploring the cheap, bulletproof quad space.  I got the idea from a post on diydrones.  The frame is pretty cheap... I paid $2/noodle at Target, but the cashier told me she bought some at the dollar store for $1.  I cut the yellow arms and the red and green cross pieces to 15-1/2'' lengths, as that's what the Arcticopter is.
The build is super-easy.  I screwed the motors onto some thin plywood, and just attached the plywood to the arms with zip ties.  Don't tighten it up, or it will compress the foam. I think tape would work just as well, and might not be so compressive on the foam.
I cut the noodles with my hot wire cutter, and glued them with Beacon Foam Tac.  It really works well.  White Gorilla Glue would probably work and might be a bit cheaper.  I cut the curves using a pattern cut by a 2'' circle hole cutter.  I might run some packing tape from the top of the red and green cross braces around the yellow arms back around to the bottom.
I used my handy Wago Connector power distribution system.  It was nice coz I needed a bit of extra length to get the wires down the H frame.  If after flying this looks like a reasonable thing to carry on with, I'll see if I can't run the wires through the noodles and eliminate some of the clutter.
I zip tied my KK2 board in the center, after cutting out a flat spot for it to sit on.  I've got a Flip on order.  I'm using a huge Rx coz it supports CPPM.  I will never use anything else with a flight control board... it's so nice having to manage just one wire!
I cut a slot out underneath for a 3S 2200 mAh battery.  I hadn't planned out the size, but got lucky that it just fit. It's being held on with a velcro strap
The top side of the foam arms and cross braces are reinforced with 3mm CF tube.  It took 4 15'' pieces.  I wanted to try some 1/8'' or 3/16'' fiberglass kite rods, but couldn't find any local suppliers.  So, the most expensive part of the frame is the embedded CF tube.  I taped the bottom of the arms with reinforced packing tape.  I goofed up on the red and green cross pieces and glued them to the yellow arms upside down, with the CF rods on the bottom.  Hope that's OK!
I embedded and glued the CF tube in a slit down the top.  The idea is that the stick will resist compression, and the tape will resist pulling.  The resulting arms are pretty stiff, although there's a bit of X-shaped flex in the overall frame.  Of course, coz it's built from pool noodles!  If it's too bad, I'll add some X bracing.

I'm going to add LED light strips inside the arms.  This should make it a quite colorful night flyer!

I flew it indoors in a quick test... it needs some tuning, but seems to fly without trouble.  I dropped it down from about 6' onto the floor. It was great, it just bounced when it hit.

Even though it looks a bit inelegant to some eyes, I think it might be a great trainer... the colors make it easy to keep visual orientation, you can see it in the evening, and it should take a crash as robustly as any frame can.  I'll post an update and video when I get it into the air.

My Main Circuit Board Was Changed

Interesting!  I'm told this writing on my Turnigy 9xr says "the main board has been replaced."  I wonder what that means?

BTW, I confirmed it's an ATMega 128, and OpenTx puts 30 models in the menu.  Sweet!

Update: contacted HobbyKing, they offered $20 compensation which was fine by me.  Everything seems fine, and that will be plenty to order a replacement motherboard if this one ever dies.

blogodex = {"idx" : ["HobbyKing", "Funny", "Turnigy 9xr"]};

Sunday, July 7, 2013

SMD LED's Seem Quite Small...

 ... Until you get the bright idea to use SMD resistors to save weight! See the tiny white thing?  That's the LED.  And the little spec beside it, that's the resistor.  I had no idea they would be so small... it didn't occur to me that the ebay vendors would be photographing those things in such closeup.  I'm going to try to see if there's a larger size of SMD resistor.  Ideally I would be able to solder the resistor directly to the LED, forming one piece to mount.  BTW the white thing in the upper-left is the package of 50 resistors.
Here they are getting ready to be soldered.  It turns out that it's possible, but I didn't get any pictures of the soldering process, mainly because I wasn't optimistic enough to have a camera ready.  I'll follow up with some notes on how I did it and some pictures.

This is for adding some nav lights to the ladybird.  If there were some ready-made ones I think I would buy them without hesitation, but it's been educational learning how to deal with such tiny pieces.

Thursday, July 4, 2013

Cheapie Office Copter

 So Crash Hancock recently issued a cheapie quadcopter challenge.  He did a great job on a cheap blue wonder based propulsion system, and of course the $15 flip control board is the obvious way to go.

He ended up paying less than $10 for the frame parts... quite good, but it occurred to me you could do better.  While mulling this over and trying to think of cheap arms, I happened to notice some rulers in our office copy room.
 Eureka!  They were just the right length, and using some jumbo clips held them together nicely.  I had some a zip tie sitting around, so after clipping everything together I wound a zip tie around everything.  As you can see, it makes a very stylish looking X copter, with about a 30 second build time!  Surprisingly, it's a very stiff frame, and very crashproof (I think), since everything will just pop apart, ready to be reassembled.
I was planning to screw the motor mounts onto the arms, but it occurred to me that they would look pretty odd when I returned them to the supply cabinet.  No problem, a couple of more clips hold the motor perfectly.  And several cents saved on fasteners!  As soon as I get some more motors and a flip controller, I'll finish it out.  Until then, everything back into the cabinet, ready to be reassembled!