Zii Battery Box

So I cut out a battery box for the Zii... After checking with Andreas, I trimmed the foam on the indentations of the front box at the front and back edges.  White PU for attachment.  I set the front and back boards of the box such that they would transfer shock along the side and bottom boards.  I routed out some battery strap slots (the middle one by hand, in case you can't tell).

Initial box cut, a little bit tall.  I whittled it down with a fresh-bladed box cutter.

Not too bad.  Fits snugly in the slot.

Oh no!!  It's just a bit too narrow for the 3S 3000's!  It's pushing one side out... That will affect the structural integrity in a crash, so I may recut the box.

Here's the batteries snugged in and tied down.  Will talk to Andreas about the best place to put the APM, receiver, and ESC.

Zephyr II and ArduPilot Layout

Here's a few notes by Andreas on laying out a Zii with an Ardupilot Mega.

This is his first Zii.  One 5000 mAh 3S or one 3000 mAh 4S battery is placed sideways at the nose.








In his second Zii, he started with a plywood battery box.  He cut this himself; it's sized to hold two 4000 mAh 3S Turnigy Nano batteries.











To keep the radio components separated, he:

• moved the video transmitter all the way to the winglet
• put the RC receiver is in the center of the wing on the opposite side
• put 3DR radio close to the APM in the main compartment

He mounted the ESC above the APM.

Zii Battery Tray by Team Blacksheep

Trappy explains:  "the battery bay is there to make your ZII durable. on our tests we dived in vertical from 30 meters on purpose. the forces get spread evenly and the 6mm plywood takes most of the beating, protecting the battery and the ZII. Use lots of gorilla glue when glueing it in, the glue will enter through all these tiny holes in the ZII Bay and make it really strong."

Product page here, forum discussion here.  Lots of detail from Trappy, be sure and check it out!

Zephyr II glued up!

Got the body glued up... wasn't quite sure what I was doing with the 3M 90, but it went not too badly.  That stuff is sticky.  I got some on my hand and had to wait for the next day for it to wear off.

I didn't get good coverage on the tips, but a bit of epoxy seems to have set things right.

I followed Chris' video for the motor mount installation.  It worked well.  I used a skinny hacksaw blade, so the motor mount was a bit of a tight fit and caused some cracking of the foam.  A bit of epoxy set things right.  Next time, I'll use a fatter blade, or make extra passes with the skinny blade to hollow the slot out a bit more.

Zephyr II bay measurements

I didn't see these online anywhere, so I made a few quick measurements, close to at least a couple of mm.  If there's more than one depth measurement it's front/middle/back.

            length  width  depth
    front bay  152    110  35-40-38
    back bay    70    110  20-15
    servo       53     40  20

Kicking off the Zephyr II build!

 Well it looks like our favorite uncle in Hong Kong is ALMOST ready to send a gift to me, so it's about time to get my Zii build kicked off.  Here's a couple of pictures of the Zii kit out of the box.  Andreas loaned me his can of 3M 90 spray adhesive, and I picked up a can of flat black spray paint.  Here's everything as they came out of the box.  The wings were wrapped in foamy wrap.

 Here's the (optional) gopro kit and skids come in one bag.

 The motor mount, battery compartment cover, and wing tips come in another bag.  There's a bit of cutting dust from the wing tips, so it seems like they're CNC milled?  Chris has a nice video about attaching the motor mount that you should watch before starting to build.

Left to right, the (optional) covering, spars (2 black, 4 white), and balsa ailerons.

Zephyr II launching notes

From Chris:

Launch with 3/4 throttle to full power.
Align elevons to match wing top foil contour out by the wing ends
and give 3 to 5 clicks of up.  If you align with bottom you will
stall it as soon as you launch and naturally try grab for elevator
up.This will also cause the roll out during the tip stall, its not
an issue with lateral balance , its you stalling it by too much up
input and no airspeed.
Once you get it flying and trimmed power on then do a few passes
under good power and chop the throttle to see if she rises or drops
once power is removed.  If it does either than your thrust angle
is off ,and will need to adjustment.
Launching it with no power and holding it back by the prop opening
is just asking for finger slicing issues.

Drone Downed in Stormy Sea, Rescued by Daredevil Sailor!

Have you ever worried that people might take you too literally? When I tossed off the EastBay C tagline ("come fly with Mark in the lovely San Francisco East Bay") this is certainly not what I was thinking!

I went out with Andreas today... he had figured out the problem he was having with his FPV receiver -- a bad connection on the ground station -- and had everything ready for trying out out FPV + ArduPilot.

First, the good news... APM + FPV is a great success.  Fly-By-Wire mode perfectly controls the plane while flying FPV -- smooth turns, no problems with oversteering etc.  And if you ever get disoriented, a simpe flick of the switch puts the plane into loiter mode while you get things figured out.  It's also great for switching pilots... pop into loiter mode, swap the video, and take up where the first pilot left off.

Things were going great, when suddenly the receiver lost connection; being in fly-by-wire mode, the Zii was content to continue flying the direction it was headed -- North, towards Marin County.  Andreas headed after it, with me following behind.  He ran towards the north part of Chavez Park, and found a lady who had seen the Zii fly by.  In fact, she had seen the Zii land in the water.  Here's the view, facing north; Point Richmond is in the background. It's sort of visible in this picture here.  Andreas was not in a cheerful mood at this time... when I pulled out my phone to document things, he sort of groaned, "do you have to be taking pictures of this?"

We sat and watched the Zii in the water for a while... the wind was blowing back to us, and it looked like the plane was getting closer.  Unfortunately, the tide was moving to the west... the plane got closer to us, and then started moving away, floating towards the southwest. We weren't sure if it was floating towards San Francisco, or if it would veer out to the Pacific under the Golden Gate bridge.  I snapped this picture as the first Zii framed by the Golden Gate.  Trappy, I hope you're impressed!

There were a couple of sailboats around, and I thought we might be able to get one of them to come to the rescue.  Unfortunately, they were a bit too far out to communicate with.  But that gave Andreas an idea... he had a friend with a boat that sailed out of the Berkeley Marina.  He pulled out his phone, and made a call. Miraculously, the friend was driving over the Richmond Bridge... he would turn around, and be there within 30 minutes to launch a water rescue.

Traffic was good, the boat was launched quickly, and it came up the west side of the Bay.  Andreas saw the boat, and pointed out the Zii. It's just where his hand is.  We passed the time speculating about which pieces of the plane could be recovered.






Time between initial distress call and rescue, 27.5 minutes.  Hooray Captain Tim!  And our friend Jim who had come out with us did a great job of making sure all the gear didn't walk away.  Hooray Jim!

 Here's the recovered Zii.  The plane is in perfect condition -- nice job, RiteWing!  The GoPro was fine as well.  Wiping off some water, it was still powered on and running well.  Too bad we didn't have it recording all that time!

 RiteWing flyers, the choice of amphibious flying professionals everywhere!

Electronics:  The battery, APM 1, receiver, servos, and motor seem to have survived.  The battery compartment wasn't filled with water... the Zii must have landed smoothly and stayed flat the entire time.

The  GPS, XBee, and video transmitter were lost... it looked like there was a current active on these devices, and the brackish or salt water caused the power pads on the board to corrode away.

Here's the last logged location, at the northwest tip of Chavez Park, and heading north.  Strange,  that as soon as it went over water it seemed to lose power and stop logging.  Is the City of Berkeley running some nefarious experiment here, perhaps left over from the 1960's?  Will Chavez Park suddenly disappear in time?






Lessons learned

• Fly with a transmitter/receiver that has a Failsafe.  Ironically, Andreas' Christmas present was a FrSky Tx/Rx, still on its way from HK.
• Fly with the GoPro in the hard case.  This is only incidentally from landing in the water (hey, it survived that fine!) but from taking a tumble in a landing previously.
• If the plane loses connection, try and recall it immediately via the ground control station.  Andreas was downfield when connection was lost.  I was at the GCS, but didn't know that the connection was lost until I went to check with Andreas.
• It might be worthwhile to investigate a method for waterproofing onboard electronics.
• Always turn your GoPro on, even if you don't plan on an "interesting" flight!

Ritewing Zephyr II + Ardupilot Maiden

Great success with Andreas' Zii/APM combination.  Flew beautifully, APM control was good, able to tune things in the air. All around a great success and left everyone feeling very pleased.  Andreas has named it Beast of Kandahar.

We flew with two batteries... 3S/5000, and then a 4S/3000.  The 3S seems to provide plenty of power -- enough to accelerate straight up. Andreas had also just upgraded the power system to:

    NTM Prop Drive 35-36A 1800
    Turnigy Trust 70A
    10x6 prop

Ground Video. This contains most of the flying modes, takeoffs, landings, and low passes.  I'll make a trimmed down version later if this one seems repetitive.

Airborne Video.

Maiden Flight, Andreas' Zephyr II

 Just got back from Andreas' RiteWing Zephyr II and wanted to get this uploaded as quickly as possible.  It arrived yesterday, he got it ready to fly in a day... send me a quick note to see if I wanted to run out and give it a try.  Yes I did, so off we went!

Even with a 5000 mAh battery, the inital flight seemed tail heavy.  We added in another battery as ballast, and also fiddled with the subtrim.  It looks like, as expected, it won't be a problem to load the thing down with FPV and autopilot equipment.

Launching turned out not to be as much of an issue as we feared.  When the prop is wound up it handles the weight of the plane, so the launching assistant just needs to keep it flat as it takes off.  Don't hold it by the conveniently located motor mount though, even when just carrying it around!

I took it for a small flight so Andreas could get a feel for the throwing.  It handled very nicely once it was trimmed out.  At half throttle it would hold its heading and altitude hands off.   You can see how smooth it is in the video when it comes in for a landing.  Chris Klick mentioned that one of his goals with the Zii was to make takeoffs and landings easier... I would say he succeeded admirably!

Here's some video of the maiden, taken with my iPhone at the lovely Berkeley Marina and rendered in genuine ShakyCam (tm).  There's a seagull that chases the thing around. Andreas interpreted it as agressively trying to chase the Zii away, but I think it's such a good looking wing that the bird fell in love instantly.  Can the Zii outrun a seagull?  The suspense will thrill you!