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Archive for May, 2009
Posted by Jack Crossfire | May 30, 2009 @ 09:44 PM | 4,327 Views
Something 4 U to think about

A micro paraglider. Use throttle for altitude & a coil actuator for yaw. Fold up the parachute & put it in your pocket. Never been documented before. Someone in China should have one ready in a couple months while...

Calif* is out of money again

2 months after U voted for higher taxes again, BARF ran out of money so U raised BARF fares another 6%. A day after raising BARF fares again, U, wait for it, ran out of money again.


Guess 10% wasn't all the sales tax U would ever need. Maybe 15% is all you'll ever need. It's a temporary increase of course, because next month it'll be 17%.
Posted by Jack Crossfire | May 30, 2009 @ 04:17 AM | 4,451 Views
The answer is yes. A heat gun can desolder SMT chips. Good news if U plan on many revisions.

20 minute exposures still aren't bulletproof. Need to dilute only enough draino to cover 1/2 of the bottom of the container & keep using the cotton swabs. Only took 1 hour to expose & etch the last board.

Remove contact lenses before soldering. That gives objects 20 microns away the same sharpness that normal people see 20 ft away. It's like going to atomic force microscope mode.

After another 2 hours banging on the soldering iron & getting nowhere again, decided to blast it with the heat gun to remove it. It automatically centered itself on the pads, joined all the solder balls, & started working!

That probably won't work for anything that blows away & U need guess when to stop blasting.
Posted by Jack Crossfire | May 29, 2009 @ 12:32 PM | 4,504 Views
Lost 1 to the draino. The draino was the same concentration as yesterday but real active for some reason. Then for the next 2 hours, had board after board expose unevenly from 5 minute exposures. After giving up on having any blog material by the next commute, exposed 1 for 20 minutes & it was the most beautiful photoresist in the history of photoresist board torture.

No-one ever used 100W fluorescent spiral lights before so there was no way anyone could guess 20 minutes. Unfortunately, couldn't get it to work before commuting time.

There it is. The most complicated board U can make in gEDA without going more insane than U already R. PCB has the 2nd worst user interface ever made, matched only by Windows itself. Got it down to 28x30mm. It could be much smaller if it was double sided, but we have to subsidize your mortgages.

To program the XBee, we have sort of a header. The PIC has to be in reset mode to override its serial output. The PIC programmer uses the same pins as PWM, a high risk design.
Posted by Jack Crossfire | May 28, 2009 @ 12:16 PM | 4,404 Views
60 minutes into the draino, realized there was no way to do more than 1 gyro per commute. It takes 2 hours to etch a board. The yield on these boards is too low to combine multiple designs in a single etch. 3 hours later, Gyro #2 started working. The mane problem is there's no way to test the connections on a leadless package. U just keep reheating all the connections over & over until it works.

There's no budget for a hotplate to test the Nate method & everyone besides Nate says it just detaches the pads. Assuming we keep getting time off, you'll have an IMU on Friday & the computer board will have only leaded packages. If U can figure out an optimum layout, U'll have 1 more day of driving to Santa Clara for parts before that board is fabricated. Didn't have enough money to buy it all.
Posted by Jack Crossfire | May 27, 2009 @ 12:01 PM | 4,757 Views
There it is. The LISY locked & loaded. Took 4 hours to get it working. Chees n crackers that thing was hard to solder. U SMT worshippers R crazy. Mutilated those SMT components nicely, but only needed 1 rework, an SMT world record.

Unfortunately, before U can build Vika3, U need to fabricate all the electronics & prove they work on Vika 2. That means a complete flight computer needs 2 B made out of SMT parts & soldered to Vika 2. The flight computer has no leadless parts like the IMU but it has many vias. Probably going to fake the vias with wrapping wire.

The Vika3 budget is limited by LCROSS. Really wanted to find a telescope in September for photographing LCROSS & that means you're lucky to get $300 for Vika3.

Focused on mirror lenses. 800mm at F/8 may sound horrible, but digital cameras R heading to ISO 20000. Would expect it to mainly do astronomy. Mirror lenses being what they R, U'd only want the cheapest.

In lens school, we learned all consumer lenses R made by Tamron. Opteka, Rokinon, Bower, Phoenix, & Vivitar R probably all the same. U ever go to lens school?
Posted by Jack Crossfire | May 26, 2009 @ 12:20 PM | 5,120 Views
With the SCP1000 altitude sensor, we're using very aggressive landing & takeoff programs to get these missions done as fast as possible between commutes. That means U need stronger landing gear. Contact lens bottles R on the scene again.


Well OK, we did integrate picoc as a runtime thread in VicaCopter. It locks up, it doesn't do floating point, it crashes your entire autopilot when it encounters an internal error, but after working around all the problems, managed to get some nifty flights out of it.


is now

#define RANGE 10


What a revolution. It's like turtle graphics with a very very expensive turtle. U can build up incredibly complex flights out of reusable maneuvers. U can repeat maneuvers. U can nest maneuvers in maneuvers. Too bad none of U R old enough to remember LOGO.

Ironically, picoc was written to fly airplanes but its author never flew it in an airplane. VikaCopter is the first airborne use. His only application was that Surveyor rover.

If VikaCopter had any more flight time, she'd probably get an interactive interpreter.
Posted by Jack Crossfire | May 24, 2009 @ 08:41 PM | 4,723 Views
Chinese proverb #1: Even motor windings can break

Chinese proverb #2: There R people in this world who wind their own motors.

Chinese proverb #3: It's a good idea if U buy Chinese motors.

Did horrible in motor theory class. Just learned to recognize which equation to use for which problem, but learned nothing about picking wire guage, winding count, poles, phases, termination.

Reading through


kV determines winding count which determines wire guage. Use the largest wire which can fit on the stator. Anything U rewind 4 a trirotor has to be done for 3 motors.


So U want something more powerful than VikaCopter's UAV programming language. Your best option is to keep using VikaCopter programming language & compile a higher level language into it. The other option is to run picoc in a thread & have it send 1 VikaCopter assembly language command at a time. Have those function send commands block until VikaCopter advances the command pointer.

How about some Picoc notes.

Run a C program by calling picoc() with a pointer to a string of the source file. It returns when the program finishes.

Create C library functions by adding lines to struct LibraryFunction CLibrary in clibrary.c. Then create native functions in a platform_*.c file. These can just print out lines of VikaCopter assembly language.

Well, now U have 2 languages: VikaCopter pico C functions & VikaCopter assembly language.

If U go with the preprocessor, there's no way to translate branches & conditions in picoc to branches & conditions in VikaCopter assembly language. It would expand everything based on compile time conditions.

U really need a function which scans a frame of video & determines the next navigation command by return value. The next step is remote control by body gestures instead of ground stations.

Vision activated commands would have to be branches in VikaCopter assembly language & not native autopilot functions.

The payoff is loops, complex expressions, variables, nested functions.
Posted by Jack Crossfire | May 24, 2009 @ 05:06 AM | 4,977 Views
Time for your first SCP1000 demo in 20mph wind. It's also your chance to see the latest in navigation tuning, fulltime GPS power. U know how most VTOL demos slowly crawl through their waypoints. Well take a look at how fast VikaCopter screams through these missions.

SCP1000 altitude control (4 min 1 sec)

According to our unbiased gyro biased panel of tri rotor judges, this is the optimum barometer placement & the barometer bandwidth should be down to 0.125. With 11" propellers, it's really solid in the calm air. The T-Rex never had enough space to mount a barometer.

Dug up our old waypoint missions from last year & ran through a few. There's no problem with vortex ring state & automatic takeoffs anymore. Automatic landings R probably slightly faster than GPS.

Mind U, we're hard coding collective to get her into the first bit of ground effect, then ramping. It keeps U from dragging on the ground. The barometer is so sensitive, the collective hardly ramps at all before going into altitude seeking mode.

Ublox5 could do just as well, but not consistently & certainly not with today's satellite outages. Sometimes we power cycle it to see if full time power makes any difference, & it does. Had a pretty serious GPS glitch which sent us into a tree.
Posted by Jack Crossfire | May 22, 2009 @ 08:11 PM | 4,942 Views
The day job gave Friday off so we could get some work done instead of pay off your mortgages. The SCP1000 on the tri rotor was as advertized on the T-Rex. Lots of noise in the rotor wash. Lots of drift in the sun. We have more placement options than the T-Rex so hopefully those problems can go away. Certainly no lag in the pressure changes.

It's not as delayed as last year because we're using high speed mode instead of high precision mode. Clearly a lot more magnitude in air pressure changes, but is it just rotor wash?


The shuttle takes 200lbs of paper to orbit, mainly cue cards & reference manuals. Computers aren't reliable enough to do the job. U take no paper to the flying field.


When fighting a war, U need to avoid giving away your position by launching UAV's. Every man portable fixed wing must be hand launched & give away your position. What about copters?

U can stash a copter far away from your position & have it take off outside of line of sight, unattended. That's a good idea for a demo. Just need to get some Americans to play the communists.
Posted by Jack Crossfire | May 21, 2009 @ 12:47 PM | 4,936 Views
Spent $60 on an SCP1000 breakout board over a year ago, but the cost of buying something & not using it all this time is less painful than the cost of having to put it back in. It means doing the same thing as everyone else, adding more weight, more wires, surrendering to the new normal of free SUV's & broken GPS.

Our previous data started on May 06, 2008.


Pressure sensors suck. For the amount of taxes U spend on GPS, they're like spending 75% of your income for a car & walking.

The SCP1000 locks up at random. It starts sending the same
reading over & over even though DRDY is toggled. Pretty sure this happened last year, but we never bothered blogging about it. It only makes sense in terms of some electrical interaction on the airframe mounting.

If the budget for a Vika 3 tri rotor ever made it, you'd have 1 micro copter & 2 full size copters to read about. After the sonar derating & the loss of GPS altitude, operating 2 full size copters doesn't buy much anymore. Vika 2 would have to use the Maxbotix EZ1 for altitude.
Posted by Jack Crossfire | May 20, 2009 @ 12:53 PM | 4,838 Views
GPS had a pretty big loss of performance recently & it seems due to the loss of satellite 5 on Mar 26. Your communist government doesn't have enough money to keep all 34 satellites going, so it's paired satellites which it thinks R about to die with newer satellites in the same plane, & that's 5 & 12, 3 & 6, 9 & 27, 7 & 25, 30 & 1. Unfortunately, 5 & 12 was the pair used during our normal flying time.

The effect is greater sensitivity to interference, degraded altitude precision & that means you're probably getting back the SCP1000.

All the media is reporting is "an increased likelihood that in 2010, as old satellites begin to fail" & "the first replacement satellite is expected to be launched this November, some three years after the original launch date." Whatever it takes to keep your mortgages solvent, but we know they're already dying.


While Arrow shipping only took 1 day, the passives R still a week away, so instead, how about the highest resolution photos of the LISY300AL ever shown on the internet.
Posted by Jack Crossfire | May 19, 2009 @ 12:22 PM | 4,558 Views
All because of those gyros doubling in price, now your bank needs double the bailout. Now your government needs to print double the money.

Ghetto IMU damage:

Passive components: $44.21
Gyros: $53.92
Transparencies: $32.76
Draino: $7
Ferric Chloride: $10.96
Photoresist board: $13.16


U know, it would have been cheaper to buy $90 of $parkfun breakout boards. Hopefully this'll come out cheaper in a few more boards. We can now build lighter boards for everything.

The actual cost of ghetto IMU consumables in 5/17/2009 dollars:

Gyros: $30
Passive components: under $1
Photoresist board, transparency & chemicals: under $2

Obviously much more in 5/18/2009 dollars, but at $33 it's not your normal IMU.

Then there's the Feigau spin copter disaster:


How R U supposed to recover that in a tri rotor?

Cost to use 2 more Feigau's + Chinese ESC's in a tri rotor:

Feigau 17g 150g thrust $33 * 2
Micro servo: $20
Tax: $8.6
Supersimple 10A $8 * 2
Chinese shipping $30


Cost to buy ESC's locally:

Feigau 17g 150g thrust, 3" propellers $33 * 2
Micro servo: $20
Castle 9A $25 * 2
Tax: 11.6


Cost to start over with chinese parts:

AD-C5 Micro Motor 4.6g 90g thrust, 2.5" propellers $18.20 * 3
Supersimple 10A $8 * 2
Chinese shipping $30
Micro servo: $20
Tax: $2


Batteries are the same. Hobbycity says those AD-C5's can't make as much...Continue Reading
Posted by Jack Crossfire | May 16, 2009 @ 07:55 PM | 4,930 Views
Exposed it using the 2 transparencies, 26W fluorescent light, distance of 18" for 5 minutes.

Dunked it in the most diluted draino possible. Had just enough draino to wet the bottom of the container & the rest was water.

Fluid flow affects the developing rate. Wherever U grab on the board is where the fluid is most turbulent & that develops the fastest.

As it developed unevenly, dunked just the parts which needed more developing. Eventually should use q tips. Slowly dunked & rinsed to remove the tiniest amounts.

Photoresist stood up better against ferric chloride than it looked. Even though it was faded, got solid traces. Concentrated, 80F ferric chloride was good enough to etch.

Dunk it in a container of water to stop etching. It avoids splashing pure ferric chloride around the sink.

After etching, dunk it back in the draino to remove the last photoresist.

The Nate Siedle technique of running a solder ball over it sort of works. U need to constantly melt fresh solder, let it bridge, then suck the excess. Apply the solder with pulling movements, like a felt pen.

Expect to destroy most of the boards in the draino. This is really a matter of luck.
Posted by Jack Crossfire | May 16, 2009 @ 04:26 AM | 4,850 Views

So the laser printer isn't dark enough. Even 2 transparencies aren't enough.

Did learn U need to dilute the draino 10:1 or it'll dissolve everything instantly. Keep the draino off your skin or else. The best result used ordinary copier paper & 10 minutes of baking. Need to find someone with a super dark printer.

One other thing. No-one sells transparencies anymore because everyone plugs their laptops into projectors. So that's transparencies & inkjet printers in the list of extinct requirements for DIY photo etching. This is yet another one of those myths which could only work for the 1 guy in outer Gainesville who still uses transparencies & inkjet printers for presentations.


Got it locked indoors & swapped the aluminum in & out. Didn't notice a single difference. Between changing satellite coverage, microprocessor interference, & fuselage conductivity, even if there was a change, U couldn't say "Bingo! It's the aluminum."

When the GPS locks, its sensitivity goes up to the maximum, so any change in signal strength blows up.

Note that our uBlox5 lost its configuration after 3 weeks of no flying. Obviously the settings are what's backed by that battery & not the ephemeris. U better have initialization in software.


Ideally U have an SCP1000 away from rotor wash. We just hate copying everyone...Continue Reading
Posted by Jack Crossfire | May 15, 2009 @ 12:22 PM | 5,041 Views
Photoresist board: $11
Incandescent Black light: $5
Tax: $100000000000000000000

$5 incandescent black lights don't do the job. Ordinary 26W spiral fluorescent lights actually seem to work.
Posted by Jack Crossfire | May 14, 2009 @ 01:56 AM | 4,973 Views
After overcoming the shock, here R the mane budget drivers:

12mm brushless motors R too heavy for spin copters without landing gear.

7mm brushed motors don't have enough power for the smallest spin copters.

U don't have anything which can move around using sonar.

U have to recover your investment in 12mm motors & sonar before buying something else.

All roads lead to an indoor, IMU guided, sonar guided, autonomous, tri rotor home movie camera.

Fortunately, take a look at this.

The LISY300AL is mountable on a single side of 0.75x0.75" board. U can probably make an IMU for $30 + chemicals.

Originally got the laser printer to iron on toner masks. That didn't work. Now they're finding U need an inket printer for the photoresist method because the new laser printers aren't dark enoguh. Useless as always, Google.

Now today's video.

External tank with stabilization (1 min 20 sec)

No, they cannot be harvested & turned into a space station. The external tanks fall right back down into the Indian ocean after separation. They are completely drained to the pipes but it still isn't enough to get the shuttle into orbit. The shuttle uses the OMS engines to get into orbit.
Posted by Jack Crossfire | May 13, 2009 @ 03:06 AM | 4,772 Views
Spin stabilization had no way of landing. That should have killed it on day 1. Thought a blanket would be soft enough for crash landings but it wasn't. Too heavy for any kind of crash landing without destroying the propeller. Just didn't see it coming without test flights.

Total weight without sonar: 104g Only 17.5g was our crummy through hole board.

Also, even short bursts of descending power got the motor too hot. Based on motor heating, no power system capable of lifting itself with a 3" propeller is light enough for crash landings.

At full power, got enough thrust to lift itself without spinning. Didn't get enough flight time to calibrate the photodiode, but it appeared to have huge amounts of noise from either propeller reflections or motor induction.

For the spin copter to work would require the same design U see in malls, the giant styrofoam stator to land on & the tiny rotor inside. Otherwise, it would have needed a much larger propeller & much lighter power system to survive crash landings like a bladestar. Fuggedabout a world record.

Spin copter had but 1 purpose, to be the world's smallest UAV. It would have been hopeless to operate. The battery was fixed. It would have needed a pushbroom camera. It didn't excercise all the cost saving IMU measures we developed on Vika 2.

Would never spend $100 on spin stabilization if all of it couldn't be used in a backup. The same hardware can go into a micro tri rotor. It would need...Continue Reading
Posted by Jack Crossfire | May 11, 2009 @ 07:35 PM | 4,626 Views
We blew $100 on a copter so it's time for the 401k blog.

It is cheaper to pay the 10% penalty for early 401k distributions than to pay full income taxes. That's right kids. Calif* income tax is now high enough that U can move to a state with no income tax & do better with the early distribution penalty than U would taking full paychecks in Calif*. Since every other state has a lower cost of living, your tax bracket would also be lower.

It's a stupid idea of course, not because you're ever going to retire, but because paying in cash is stupid. You're supposed to be borrowing home equity. That's what mortgage bailouts R there for. Your government doesn't give free loans to first time home buyers & people with the right skin color so they can buy houses. It gives loans to make your houses appreciate 20% every year so U can buy stuff.


In the future, cash is meaningless. Everything is $100,000 & paid for with home equity. You're awarded a certain size mortgage bailout every year, based on party loyalty, race, skin color, religion, sexual preference & that becomes home equity U can borrow for some electronic root boots.


Calif* feeds on outsourcing. U lose your jobs in Montana because if it can be done in Montana, it can be done in Mongolia. U move to the main office in Calif* which can't be outsourced. The faster the internet gets, the more of U have to move to Calif* to find jobs. The more...Continue Reading