Night Vapor Improvements

Some nice Night Vapor improvements mentioned on RCG:

• prop twisting -- if you're not getting good thrust, twist the 5x3 prop to restore the pitch.
• upgrade to this beautiful 5x3 CF prop from bsdmicrorc.com.
• upgrade to an Ultra Micro J-3 Cub motor.  You will need to extend the wires but otherwise it's a direct swap.  You will be able to hover and pull out.
• add .5mm CF supports to front rod and elevator.

Arcticopter IV indoor maiden

Got everything put together and tuned.  For the video, I had my iphone sitting on its side on the landing next to me, so I had to fly in the ground effect to keep it in frame.  I had stabilization on, and it handled quite nicely I think.

MultiWii with gyros and accel.  About 9.5oz without batteries.

Encyclopedia of RC Foam

Some Vendors

• rcfoam -- EPP 1.3#, EPP 1.9#, Deppron, XPS, carbon and other materials.
• Dollar Tree -- 36x24 6mm sheets from Adams, with paper.
• Model Plane Foam -- top quality Adams foam, without paper.

Types of Foam

Here's a summary of various types of foam used in RC modeling.  I'm no expert in this area, so let me know of any inaccuracies.  Thanks to TP16 and RogueTitan on rcgroups for some of the material below.  This is a work in progress.  If you have more information or more types of foam leave a comment below!

First, a few definitions:

Expanded foam is melted and injected into a mold.

Extruded foam is cast as large blocks and cut into sheets.  In real life this foam is often used as building insulation.

Polystyrene, Polypropylene, etc, are different types of materials with different characteristics regarding weight, strength, flexibility, etc.  Wikipedia discusses them at a level of detail far beyond my freshman chemistry class.

And the foams:

EPP a.k.a. Expanded Polypropylene.very durable sheet material, bounces well, holds up to rough treatment.  Very floppy, so needs to be reinforced. comes in densities of 1.3 and 1.9 pounds per cubic foot.  Typically sold in sheets up to 24x36 inches, in 3mm, 6mm, and 9mm thicknesses.

Depron. Sheet foam, very stiff but much easier to break than EPP.  Easy to cut and sand, comes in white, gray, and black.  Used in Europe as flooring base.

Depron Aero.  even lighter than depron.  Popular in competition indoor pattern flyers.

Elapor. Trade name for Multiplex's EPP foam.  The Easy Star is made from this and is renowned for being a durable model.

Z Foam. From Horizon Hobby, this is a proprietary reinforced foam construction method.

Blue Core, Pink Core, etc. Extruded Polystyrene.  Sold in home improvement stores in sheets of various thicknesses.  The color depends on the manufacturer.  Lacks beads and is generally sandable and shape-able.

Fan Fold Foam, aka FFF.  The same material as Blue Cor, but in 1/4'' thick 2 feet x 50 feet sheets, fan-folded every two feet.  Cheap and popular for scratch-built models.  Between EPP and Depron in terms of strength and flexibility.  You can see here that it's labelled as being Extruded Polystyrene.

Dollar Tree Foam Board, a.k.a. Rediboard. 3/16'' thick, 20x30 inch. Sold at Dollar Tree stores for $1 each.  Official product name is ReadiBoard.  Flimiser than FFF, but easier to get in warmer places where FFF is not stocked.  Reinforced paper backing on both sides, people usually remove it to reduce weight.  Spray with water or window cleaner, let dry, and the paper will peel off in one piece.  Elmers foam board is similar but heavier.

EPP, a.k.a. Expanded PolyPropylene. This is another sort of bead foam. Generally held to be some of the most durable stuff out there, it can be flexed and twisted without snapping. Because of this, it's got very low structural integrity so airframes have to be strengthened by other means such as CF or fiberglass. Comes in a couple different densities.





EPO a.k.a. Expanded PolyOlefin. Similar to EPS but different as well. It's reportedly stronger and has a smoother, more finishable surface.  Used by manufacturers such as FMS.

EPS a.k.a. Expanded PolyStyrene. This is your basic beer-cooler foam. Little white beads, various densities. Note that "EPS" is also occasionally used for Extruded PolyStyrene, which is a different material entirely. Still foam, but made by -you guessed it- extruding rather than expanding.

Daemon on RCGroups notes:


EPS is easiest to do injection molding. EPO is trickier (and varies from manufacturer to manufacturer). EPP is a real pain (requires a lot more vents in the mold, which create all those little dimples on the finished product). EPS can be the most rigid, but it's also the most brittle and hard to repair as regular CA and any solvent based glue totally dissolves it, and foam safe CA has various limitations. It's the worst around heat, so can't use iron on covering and if you crush it or bend it, it stays crushed and bent.

EPP is the least rigid per weight, but is totally bounceable, does not dent or scratch and not all that hard to stiffen up with some added stiffeners (carbon ribbons and tape). EPP is the most resistant to heat so can take any covering.

EPO is a mix of the two, so it has more rigidity per weight than EPP, and it can bend more like EPP, but still will dent or scratch. If it's a "good" EPO (Skywalker EPO, or Multiplex Elapor), it can be repaired with regular CA (creates a nice chemical bond that's stronger than the foam itself), and you can take the dents and scratches out and straighten bent or crushed foam with proper application of heat (165-170 degree water or steam). Have to be careful when applying iron on coverings (Monokote,
Ultracote, Laminating film) to not overheat the foam and puff it up.


blogodex = {"toc" : "foam", "idx" = {["suppliers", "EPS", "EPO", "Depron"]};

Theraband Data

Here's a thread on RCGroups where jackerbes goes into great detail about using 1/8'' slices of blue Theraband to make high quality prop savers.

Sparklet follows up and shows how they make good vibration dampers for quad photography.  He uses it to attach two bolts together

It seems that ebay vendor drdcsupplies is the goto guy for retail quantites of Theraband.  At the time of writing it's $1.50/foot postpaid for yellow (thin), red (medium), green (heavy), and blue (extra heavy).

Full specs and info are on the manufacturer's page.  Here are the physical dimensions of each kind of tubing:


Color  Dimensions                      Part Numbers
Tan    .062 ID x .031 wall (.125 O.D.) #21010 #21110
Yellow .200 ID x .045 wall (.290 O.D.) #21020 #21120
Red    .200 ID x .057 wall (.314 O.D.) #21030 #21130
Green  .200 ID x .069 wall (.338 O.D.) #21040 #21140
Blue   .200 ID x .085 wall (.370 O.D.) #21050 #21150
Black  .200 ID x .098 wall (.396 O.D.) #21060 #21160
Silver .200 ID x .125 wall (.450 O.D.) #21070 #21170

Some MultiWii links

Got the Arcticopter IV put together with the MultiWii, but couldn't get the MultiWii Conf to talk to the board.  Have to check with Andreas to see what's up with that.

Here's a few links.

• Source and Configurator.  Needs a Java Runtime.
• Paris board setup.  The quad section starts about half-way down.
• MultiWii FAQ.

Stick Controls

• lower-left: disarm
• lower-right: arm
• lower-left / down: gyro calibrate
• lower-left / up: accelerometer calibrate
• up / up,down,left,right: accelerometer trim

Setup Notes

• sticks should be 1095 / 1500 / 1905 low / mid / high

LiFe battery in Turnigy 9x

 Here's how the 1500 mAh LiFe fits into the Turnigy 9x transmitter.

 It uses the servo-style connector.  From the left, it goes black-red-empty.  I put a sticker in so I won't forget it.

There's plenty of room inside the battery compartment.  I put the wires on the right side.  The cover fits on very easily now!

GoPro FPV Setup (cables)

Output cable is: 2.5mm 4-pole jack
From inside, connections are: ground, video, audio, unused
yellow: video with shield (ground) , white: audio with shield (ground)
connecting to servo plug:

• two grounds together, to servo black ("ground")
• video, to white/bronw ("signal")
• audio: to red ("power")

Two versions of off-the-shelf cables from ReadyMadeRC:

• generic a/v
• immersionRC specific

Nice tutorial from RCTestFlight:

The Servo Database

Truly the Internet has everything!  Everything you ever wanted to know about servos.

APM carrier for Hawk Sky and related planes

Inspired by the new Bixler Accessory Chassis on diydrones, I thought I would tidy my own setup and make my own adaptation for the Hawk Sky.  I haven't quite finished it but it looks promising enough to write up, and I think something similar would work on other models with a front hatch.

I cut the horizontal top plate using the opening as a template.  I just cut the cardboard "close enough" and then traced the opening directly onto the cardboard.  I used scissors for the cutting.

 I then did the same for the forward and rear risers.  I attached the three pieces with epoxy.  I positioned the pieces on the plane and then spread the adhesive on the front and back joints.  I used enough so that the joint didn't need any extra reinforcing.  Note that the fuselage opening bends down towards the front.  I attached the top plate to the front riser in such a way as to keep the top plate level.

 I tried a couple of different ways to attach the APM.  What eventually worked best was a cardboard carrier  bent to the appropriate size and hot glued to the top plate.

I cut some holes to run wires, see the ABC lights, and reach the reset button.  I attached the xbee and GPS on the top plate with velcro.  I didn't make a GPS mount like diydrones did; if I have reception problem I will do so.

 I uncased the Turnigy 9x receiver both to save weight and get clearance for the battery.  I replaced the standard 3-wire connectors with single wire connectors.  Later I'll get the rectangular 6-way connector and use that instead of multiple single wire connectors, but it doesn't seem to be a problem for now.

 The unit sits on top of the battery.  With the receiver case removed, there's just enough clearance for the 3S 2200 mAh 15C battery.  I velcroed the reciever on the bottom and hang the antenna wire out the side.  That's roughly equivalent to what I've been doing and haven't had a problem so far.  I provided some strain relief for the antenna by hot gluing it onto the board.

c

AUW for the unit with velcro is 13.3g. Still to do:  put some magnets to hold everything down, velcro or otherwise attach the APM to the lower carrier, and attach the pitot tubes.  I'm hoping to attach the tubes to the carrier if I can.

I'll update later when I've applied the finishing touches and gotten the thing into the air.

Spherical flyer from japan

Amazing spherical flyer from Japan Defense Dept.  350 grams, 42cm diameter, made from off-the-shelf components costing about $1,400.  Hobby King, get busy!

Article on PID tuning

Bookmarking this post for future reference; with a couple of videos.

Sugru: repairing DX6i charger port

Another note to Sugru about repairs.  This to my DX6i where the charge port had busted loose.

Here's a simple, unglamorous repair that saved me time, money, and the expense of being without a radio transmitter that I use frequently.

The battery recharging port had worked its way loose, due to a crack in the groove that holds the connector in place.  It's a standard sized connector that's available at any local electronics
store, but it turns out this particular piece is a nonstandard size and can only be replaced by sending the unit in for warranty service.

I was actually opening the case each time the unit needed to be charged; in addition to being inconvenient, I was worried that the wires attached to the case would undergo more stress than they were designed for and might work their way loose.

I considered using epoxy, but then the connector would be permanently bonded to the case, and if it ever went bad I would have even more work to put things right.

The sugru worked perfectly; the connector is held very tightly and resists the pressure when the power cable is attached;  and if I should ever need to remove the connector, the Sugro can be easily scraped away with a small blade.

The work took about 10 minutes including opening and closing the case, and I let the Sugru cure overnight before testing, so I didn't have any downtime related to the repair.  I didn't bother making it
pretty since (a) there wasn't a lot of room for my fat fingers, and (b) with any luck it will be many years before somebody has to look at the inside of the case again.  I guess if it ever gets stolen I'll have the perfect identifier -- my fingerprints permanently embedded inside the case!

And the package of Sugru was so much cheaper than the shipping cost of returning the unit to the manufacturer (via tracked mail) I'm money ahead as well!

Thanks again Sugru, you've saved me time and money!

Sugru: repairing macbook feet

I recently bought a package of Sugru.  It's neat stuff and I'm happy with the results, so I sent them a note and picture to their gallery, and reproducing it here.

For some reason I seem to be pretty hard on the plastic "feet" on the bottom of my macbook pro.  I've busted three of them right off and the fourth was looking pretty dodgy.

So, I popped the fourth one off and replaced them with sugru feet.  I used one package of black sugru, divided it into five equal pieces and reserved one piece for an unrelated repair. The remaining four pieces I shaped into chubby "coins" the same size as the original feet.  Underneath the feet the case is open to the inside, and I wanted to be careful not to fill up the guts of the computer by squishing the Sugru through the holes.

Using pressure around the edges gave a nice convex surface and ensured a good bond with the case, in addition to keeping the Sugru on the outside of the case.  After it looked like all the feet were pretty equal, I put a bit of soapy water on a flat tabletop and set the computer down for a second or two to make sure everything was level and the unit wouldn't rock.  I turned the computer over to let the Sugru cure.

The Sugru is working much better than the original plastic feet. In addition to being a lot more sturdy, the grip of the sugru on a desk or tabletop is excellent.

And as a bonus, my macbook pro got much quieter!  I had not realized how much of a loud hum the disk drive made with the missing foot.

Thanks Sugru, I don't know what else would have worked so well!

What's a "400" size motor?

I've seen this specification mentioned many times and couldn't ever find out exactly what it meant.  A quick query on rcgroups and all has been revealed!

Here's the original Graupner Speed 400. It was one of the original brushed electric motors when they started to be introduced.

DragonPlate Carbon Fiber

These guys look like the Leonardo Da Vinci's of the CF world... every possible formulation of CF: sheets, rods, trusses, tubes, core sheet goods, with a gorgeous mirror finish.

Motor Balancing

Not just props, you should balance your motors too:

• http://www.rcgroups.com/forums/showpost.php?p=15936915&postcount=8839

EasyStar upgrade

(Oldie but goodie... I typed this in and didn't publish)

Here's some notes from Andreas on some mods he has made to his EasyStar.  (It's interesting how we met:  he lives about 5 minutes away from me in our little town; he dropped me a note after reading a comment I had left on rcexplorer.se.  I've worked with one of his old neighbors for almost 10 years!  It's a small and crazy world!)

• To really make the Easystar fast, you need a brushless motor, esc and lipo. I just used the equipment from the first helicopter I wrecked. Original propeller fit too. With that power I can fly in any wind with no problem. Performance similar to this rocket.
• This is a full mod-project but I did not find any structural re-enforcement necessary:
• The Easystar's rudder is too small. Especially once you add more power. I found this credit card trick the simplest and very effective.
• All hinges should be replaced with real plastic hinges instead of just bending the foam.asdfa
• Also the center of gravity is often too far aft, even on stock EasyStar. Must add enough weight on nose to make it controllable. So I think it can lift a lot of weight (FPV, more electronics for your autopilot etc).

Update:  I've done all these and they make the EasyStar a very nice flyer.  I changed to a Hawk Sky for the ArduPilot platform.

By The Numbers: LiFe batteries

Lithium Iron Phosphate (aka LiFe, LiFePo, LiFePo4) batteries are most often used in RCLand for transmitters.  They're safer than LiPo, since they don't emit oxygen during rapid breakdown leading to combustion.  Lots of chemical detail on wikipedia.

Here's the model that fits into the Turnigy 9X transmitter.  Use the servo-style connector to plug it in.  Note that there are two ways to plug it in: only one of them works; the other doesn't do anything.

Charge Levels

 1S   3S

3.3   9.9  nominal voltage

2.8   8.4  minimal discharge

3.6  10.8  maximum voltage

Charging

You need to set your charge into LiFe mode.  Don't charge in LiPo mode. Bruce has a video here that explains how to do this on a standard 4-button charger. Here's the tldr for a typical 1500 mAh 3S:

Save Data / 01 / LiFe / 9.9 / 1500 / (hold start) / 1.0 / 9.9 / (hold start)
Save Data / pgm number / LiFe / voltage / mah / (hold start) / charge current / voltage / (hold start)

xbee causing odd servo jittering in APM?

Here's an odd thing that happens in my office.  I haven't noticed it happening in the field.

• when powered up, the servos constantly jitter
• jittering seems to be going through the APM... note the period of time when APM is booting and jittering stops
• jittering associated with 900MHz xbee
• if the xbee is disconnected, no jittering
• if I ground the xbee by touching the antenna, jittering stops

I'm curious as to the cause of this; partly to see if there's a problem, fix, etc, but mostly to understand what's going on. The primary practical issue is that the jittering noise seemed to make people nervous as they were looking at the unit.

update:  It seems to be noise from the radio.  There are quite a few postings on this in the diydrones forum.  Applying a ferrite ring on the cable between APM and xbee seems to be the recommended fix.

Xoar Props -- big and wooden

Xoar International has really nice big wooden props.  They've got a placeholder on their site for multirotor props.  The OMStudios MikroKopter is using them.

Nice airbrushing

rcgroups maven hance has a nice way of airbrushing superflys.  Cut a template like this, move the two pieces apart, and you can use one piece as a mask for the other.  Check out the article, it's got two ideas for how to use this, with a bonus pic of the charming Mrs Hance!

FTDI and AVR cables

Here's a quick brain dump of the differences between FTDI and AVR programming cables.

• Arduino things use the FTDI adapter.  FTDI is basically a serial/usb converter. 
• FTDI is a company, their main product is a serial/usb chip.
• The Arduino boot loader has code to handle the ftdi loading process.
• Shown is the Solarbotics FTDI basic breakout.

• The KK Board is more hard-core, non-arduino, "pure" atmel.
• AVR programmer is used to "flash" the on-board chip memory, like writing an eprom.
• If you want to take an atmel chip and make it into an arduino chip, you would use an AVR programmer and flash the arduino boot loader.
• Likewise, you use an AVR programmer to flash the kkboard software onto the atmel chip.
• Daddy87 has a great tutorial here.

• "Name brand" AVR programmers are, ironically, more expensive than the HK KKboard .
• But, lots of cheap vendors on ebay, all based on the open-source hardware design of Thomas Fischl:  http://www.fischl.de/usbasp
• This one is from ProtoStack.

cheap lightweight battery for Night Vapor

 One of the things I love so much about my night vapor is how light and floaty it is.  Turn the throttle down, you can't hear the motor, and it just effortlessly glides across the room.

Of course, a lot of this is due to its light weight.  17g AUW with the supplied 70 mAh battery.  Unfortunately, extras of this battery are $5.50 + shipping, and when I originally ordered I think it was closer to $8.00!  So of course, everybody buys the cheaper, larger batteries.

 But, that adds another 2-3 grams to the AUW.  Still it's a fine flyer, but just a little bit more speed is necessary to keep it in the air, and just a bit of the floatiness is lost.  I can compare this out the Concord Model Engineer's indoor fun fly, where a couple of other guys have night vapors.

So, when I noticed that Hobby King had cheap single battery cells, I thought I would try to make my own.

 Here's exactly what I used:

• Zippy 70 mAh, 20C cell. I bought 3 units to experiment with.
• Mini plug extension wire. Cut in half to use the female plug.
• 2mm shrink tubing.  This is good cheap stuff to fill out the weight on any HK orders.

Total cost for 3 batteries: $5.50, $1.82 each.

I've never worked with raw battery cells before, so I was a bit nervous.  It turned out to be no problem... just keep in mind that you're working with a live circuit, don't touch wires together, don't short the tabs with a screwdriver etc.

The battery tabs take standard solder.  I snipped and tinned my wire, and then tinned the battery tab, leaving a proper sized blob to attach the wire.

I then put the cell flat on a piece of wood, and lined the wire up.  Touching the soldering iron to the wire allowed me to mash the wire down onto the tinned tab, making a very nice solder joint.

On two of the cells I make a straight solder joint, so I had the shrink tube on the wire as I soldered it.  Because of this, the wires were a bit longer than I liked... extra weight, and I was worried it might not fit in the plane very well.

 So for the third try, I flipped the wire around.  This is the top battery in the first picture.  This produced excellent results:  the wire was a lot shorter, it ran alongside the battery, and I was able to put the shrink tube on after the soldering, since I could just slip it over the tab and wire, heat it, and trim.

I think I'll resolder the other two cells in the same way.



[update: solved the charger problem using the 1S extension wires from Hobby King.]

 Mini Plug Extention for Micro Battery 10cm (5pcs/bag)

 When soldering, be sure and do one side completely (all the way up to shrink tubing), and you'll have a lot less chance of shorting the battery tabs together.

The completed battery is too fat to to fit nicely in the holder, but a bit of blue tape holds in on nicely.  I might a a tiny bit of velcro as well.  When I flew it for testing, there was a bit more tape than what I'm showing here.

The batteries fly perfectly; slow and floaty behavior restored due to the low weight, and the 20S discharge gives a lot more power.  The original 70mAh cells don't have a discharge rating, but the replacement eFlight 150s are rated at 12C.

I didn't test relative flight times, coz I was pushing the testing between a couple of other activities.  I'm guessing it will be comparable to the original battery, but I'll try it later and update this post.


I've misplaced my little subgram scale, but using my big scale show the following weights:

• Turnigy 138, 5g
• Parkzone 150, 4g
• Original Parkzone 70, 2g
• These replacements, 2g (I'm assuming the 3rd one was a bit less and would show it on the higher precision scale)

But, using my big scale, the the plane's AUW including the battery drops from 17g to 16g (with no battery, it's 14g).  So, it seems that these replacements are lighter than the original, and could get even a bit lighter if I were more aggressive about trimming the wire.

They fit on the charger nicely... line them up and poke them in with your fingernail,  pull them out by holding on to both wires (not the battery body) when finished.  Note that I have to tip up the third battery to get it to fit into the solder.  When I redo the others, I'll solder on the other side of the battery (if possible?) so that the batteries won't have to be tipped up; but it doesn't seem to be enough of a problem to resolder the one that's already made.

Update: Figured out how to eliminate the shrink wrap.
http://eastbay-rc.blogspot.com/2012/01/update-night-vapor-batteries.html

Turnigy 9x Trainer Mode

Here's some notes on setting up two Turnigy 9x radios in trainer mode.  Thanks to Miki for asking about this and training new RC pilots!

I'll type in a few quick notes now; I'll try to borrow my friend's 9x, take some pictures and maybe a video of trainer mode in action.

Overview

• We'll use "teacher" and "student" here;  The other common terms for this are "master" and "slave".
• The teacher radio is in contact with the plane.
• The two radios are attached with a 1/8 inch mono male-male jack.  Student radio turns on automatically when attached.

Student Radio

• In new model 9x's (the ones with a single antenna), there is a circuitry problem that blocks the trainer port.
• The simple way to fix this problem is to pop the module out.  The antenna connection is soldered to the main board, so be a little bit careful.  You have 2-3 cm of loose antenna wire.
• With the module disconnected, the trainer port is active.  I think it's ok to operate in this mode, just tape the module so it doesn't fall out and break the antenna wire.
• Another solution, but more work, is to solder a resistor into the circuit.  I have not tried this yet, but have my notes on this page.

Teacher Radio

• Turn on trainer channels [menu / func setting / trainer].
• You can turn on all controls or just some.  It might be useful for teacher to keep control of the throttle, for example.
• The settings are confusing.  I will probably make a video, but I think you want to set Off/On mode. When in that menu, pull the trainer switch and you should see the mode switch.
• In most radios, you pull the trainer switch to allow student control, and let go of trainer switch for teacher to control.
• Turnigy 9x is opposite!  Must hold trainer switch for teacher to control.  Use this method for mechanical reverse.

Simple Summary

• Eject the module from student radio.  Tape it down so it doesn't break antenna wire.
• Make sure "Reverse" has same settings on both radios. [menu/func setting/reverse].
• Set trainer mode on teacher radio.
• Attach mono cable to both radios.
• Test all controls to see if reverse is correct on both radios.
• Fly!

Quad Dome from Electronic Goldmine

Looks like these might be nice for a quad hat; also available in red, if you like that HAL look.  Sales page says:

Green See-Thru Super Quality Acrylic Dome-The Electronic Goldmine:

"These domes make great additions to small robots. They are large enough to mount sensors, small circuit boards, LEDs, lamps, etc. underneath. Each dome is 2.83" in Dia. plus a .5" mounting lip. The highest part of the dome (at the center) is about 1" tall. These were made for large projection TVs and came in to us in sealed master cartons so they are in perfect condition. Green See-Thru.

Nice rule of thumb for COG testing

mikeruth @ rcgroups:

A general rule of thumb is on a calm day fly the plane upright and trim it out for straight and level flight at a moderate speed.
Then roll over inverted and see if you need to put down stick input in and how much. This is the tell tale sign of your CG.
3d planes typically will roll over and fly with no input and or climb becuase of the reward CG settings we like for 3D flying.
As you move the battery back, it's going to take less input or in my case require holding some up-stick just to stay level since I like a very tail heavy setup. 

Wireless Simulator/Trainer Port - update

A while back I linked to a photo of a wireless trainer port and mentioned that I couldn't find the article.

Well here it is:

http://www.hobbyking.com/hobbyking/forum/forum_posts.asp?TID=19313