Wednesday, May 9, 2012
Sunday, May 6, 2012
Turnigy Talon V2 Build: Part 1
The tricopter I built last year has been sitting gathering dust- it never flew well enough for me to have any fun with it. I've been watching the prices on the KK board clones drop in price, and when I noticed that Hobbyking released a new carbon fiber quadcopter frame I had to pull the trigger and give it a try again.
I'm re-using the 18A ESC's, receiver, and some other bits from the Tricopter. Otherwise it's a fresh build.
THe L2215 900kv motors are a bit of an unknown- Hobbyking was out of stock of pretty much everything else. The L2215's fit, but the bolt pattern only allows two screws instead of the normal four to attach them to the arms. Also, it would be better to have a motor that has mounting holes on the side of the motor that shaft protrudes from to allow the motor to be below the mounting arm. You could push the shaft through on these motors, but to do so you need to loosen some tiny allen screws- which when I tried, seemed like they really wanted to strip the heads. So I left well enough alone and mounted them without moving the shafts.
Quick review- the frame seems very nicely done. The aluminum bits are nicely machined and anodized, and the quality of the carbon fiber seems good. I did have to drill out a few of the holes on the flat carbon plates which form the center hub of the 'copter.
One of the sweet things about this copter design, is that you can run the motor wires through the inside of the carbon arms. To do so, the motor leads need to be long enough- I found that they should be about 10 inches total from the tip of the wire connector to the side of the ESC body. This provides enough length to allow the wires to be loaded through the tube during assembly and plugged into the motor connectors.
In order to add length to the ESC motor leads, you need to join wire extensions to the ESC. I used an overlapping butt joint. I also used 14 gage wire, overkill for this application, but it's what I had available. Going with some 16 or 18 gage wire would save some weight.
Once the ESC lead is inserted into the wire, I applied head with a soldering iron and wicked solder into the joint. I finished it off with some heat shrink. Again, it's best to slide the heat shrink over the wire before you add the connectors- it makes assembly much easier.
I re-used the ESCs from my old tricopter, which is why there is multiple wire joints shown in the photo above.
If you are using new ESC's, you'll want to hold off on adding the battery connector to the ESC.
The pre-cut holes in the bottom carbon fiber plate are just the right size to allow feeding the ESC and wire harness through. This will allow mounting the ESC's to the edge of the 'copter hub later.
After I inserted the screws from the bottom, I fixed them in place with two nuts per screw tightened against themselves. I then used some aluminum spacers to give enough room between the carbon plate and the power board. I think these spacers were landing gear wheel spacers from my defunct Parkzone T-28. Always part out those crashed planes and keep the misc. hardware!
After the power distribution board is in place, the rubber servo grommets can be placed on the screws. The grommets will provide some vibration damping for the control board. Less vibration = more accurate control and less error from the piezo gyros.
The 1" 4/40 screws are just long enough to put another set of grommets on top of the control board and fasten everything down with a single 4/40 nut. I might try re-doing the stack with a shorter spacer on the bottom, to allow a double-nut or locknut to be used on top. I'm worried the nuts might loosen or fall off in flight, causing a big problem.
Now the trick- how to wrangle all of the ESC's, power cables, and ESC control cables into something resembling order. It looks like the ESCs could be zip-tied to the corners of the hub. Two possible orientations present themselves- horizontal:
Vertical made more sense to me- it seemed to allow for better fit of the various wires.
Since my ESC's already had EC3 battery connectors soldered on, I had to make some short adapter harnesses. The Hobbyking power distribution board had 3.5mm female sockets soldered on. If I was using brand new ESC's I would have simply soldered 3.5mm male connectors onto the ESC's and directly plugged them into the board. That would have made for a neater and lighter installation. Also, fewer connectors = less possible failed joints. If I really like how this flies I might clean things up a bit. I'd also replace all of the 14 gage wire with lighter 16 or 18 gage.
Next steps:
I'm re-using the 18A ESC's, receiver, and some other bits from the Tricopter. Otherwise it's a fresh build.
THe L2215 900kv motors are a bit of an unknown- Hobbyking was out of stock of pretty much everything else. The L2215's fit, but the bolt pattern only allows two screws instead of the normal four to attach them to the arms. Also, it would be better to have a motor that has mounting holes on the side of the motor that shaft protrudes from to allow the motor to be below the mounting arm. You could push the shaft through on these motors, but to do so you need to loosen some tiny allen screws- which when I tried, seemed like they really wanted to strip the heads. So I left well enough alone and mounted them without moving the shafts.
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| Nice packaging. |
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| Assembled frame without electronics |
Quick review- the frame seems very nicely done. The aluminum bits are nicely machined and anodized, and the quality of the carbon fiber seems good. I did have to drill out a few of the holes on the flat carbon plates which form the center hub of the 'copter.
One of the sweet things about this copter design, is that you can run the motor wires through the inside of the carbon arms. To do so, the motor leads need to be long enough- I found that they should be about 10 inches total from the tip of the wire connector to the side of the ESC body. This provides enough length to allow the wires to be loaded through the tube during assembly and plugged into the motor connectors.
In order to add length to the ESC motor leads, you need to join wire extensions to the ESC. I used an overlapping butt joint. I also used 14 gage wire, overkill for this application, but it's what I had available. Going with some 16 or 18 gage wire would save some weight.
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| Applying flux to end of wire |
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| ESC lead inserted into center of wire |
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| ESC with added cable length |
If you are using new ESC's, you'll want to hold off on adding the battery connector to the ESC.
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| Wires threaded through carbon rod |
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| Motor mount, wires ready to go |
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| All four arms with wires. |
The pre-cut holes in the bottom carbon fiber plate are just the right size to allow feeding the ESC and wire harness through. This will allow mounting the ESC's to the edge of the 'copter hub later.
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| Mess 'o wires |
The Turnigy Talon V2 kit came with some nylon posts, nuts, and screws to mount the control board on top of the hub. However, I couldn't figure out how to use that hardware to also mount the Hobbyking power distribution board. The power power is exactly the same size and has the same mounting holes as the control board. The option I'm going to try first is just to use some 4/40 x 1" long screws and appropriate nuts, spacers, and servo grommets.
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| 4/40 x 1" screws inserted from the bottom of the carbon plate |
After I inserted the screws from the bottom, I fixed them in place with two nuts per screw tightened against themselves. I then used some aluminum spacers to give enough room between the carbon plate and the power board. I think these spacers were landing gear wheel spacers from my defunct Parkzone T-28. Always part out those crashed planes and keep the misc. hardware!
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| Power distribution board installed |
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| Control board stacked |
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| Stacked boards- side view |
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| Test Assembly |
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| Zoom view of the stack |
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| Horizontal |
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| Vertical |
Since my ESC's already had EC3 battery connectors soldered on, I had to make some short adapter harnesses. The Hobbyking power distribution board had 3.5mm female sockets soldered on. If I was using brand new ESC's I would have simply soldered 3.5mm male connectors onto the ESC's and directly plugged them into the board. That would have made for a neater and lighter installation. Also, fewer connectors = less possible failed joints. If I really like how this flies I might clean things up a bit. I'd also replace all of the 14 gage wire with lighter 16 or 18 gage.
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| ESC's all plugged in. |
Next steps:
- building battery mount
- hooking up control board
- prop & motor setup
- Fly!
- airborne photography
- FPV?
- stringing Christmas lights in tall trees?
Parkzone Icon A5 tail fix
A week ago I had a very hard crash with my Parkzone Icon A5 after a radio glitch (or elevator servo problem?) caused the airplane to dive at high speed into the lake.
The fuselage glue together nicely with white Gorilla glue. The tail, on the other hand, was a problem. The foam was crushed in one area making it really difficult to glue it back together straight. I decided to insert a small carbon fiber reinforcement to keep it straight.
I chose to insert the carbon in the natural joint between the vertical stabilizer and the fuselage foam pieces. I had to use an X-acto knife to lengthen and deepen the slot to make room for the carbon strip.
I manually held the tail as straight as possible, inserted the carbon strip, then wicked in some foam-safe thin CA. Once the strip was tacked into place, I filled the slot with some thick foam-safe CA and used some accelerator to cure it.
I haven't yet flown it.... I'm crossing my fingers that everything is straight and true!
The fuselage glue together nicely with white Gorilla glue. The tail, on the other hand, was a problem. The foam was crushed in one area making it really difficult to glue it back together straight. I decided to insert a small carbon fiber reinforcement to keep it straight.
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| Carbon strip recycled from a RIP aircraft |
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| Sizing it up |
I chose to insert the carbon in the natural joint between the vertical stabilizer and the fuselage foam pieces. I had to use an X-acto knife to lengthen and deepen the slot to make room for the carbon strip.
I manually held the tail as straight as possible, inserted the carbon strip, then wicked in some foam-safe thin CA. Once the strip was tacked into place, I filled the slot with some thick foam-safe CA and used some accelerator to cure it.
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| Finished product |
Spektrum TM1000 telemetry voltage probe installation
I recently upgraded from a Spektrum DX6i to a DX8. Among the new features is telemetry- and the new radio came with a TM1000 telemetry module, a temperature probe, and a voltage probe. For me, the main advantage is to be able to set a low voltage alarm so you can fly out the entire flight pack. This is really helpful when you might be using a range of battery capacities- on my Parkzone Icon A5 I use everything from a 1300 mAh to a 2200 mAh, which makes using a simple timer useless.
The temperature probe doesn't need any real installation- just plug it in and attach the sensor to whatever you want to measure, so very quick and easy. The voltage probe does need to be hard wired into the aircraft's electrical system. I decided to make a removable wiring harness so I could easily move the TM1000 and voltage probe from aircraft to aircraft.
Making a custom harness is very easy for anyone who is capable of soldering their own EC3 connectors.
Step 1: Cutting the wires
I used Turnigy 14 gage wire. Choose your wire according to expected current draw. I cut the wires to 2" in length. Shorter is probably better for fitting in your airplane, but it gets more difficult to solder and attach the connectors. If I were to do it again, I might try 1" pieces.
Step 2: Trim the insulation
I like using a roll cutting technique. Use a razor blade or X-acto knife and gently press into the wire insulation while rolling the wire. Take care not to press too hard or you'll cut through wire strands. You could also use a wire stripper, but for small trims like this I find the roll cutting technique to be easier and more convenient. For these connectors I chose to remove 1/8" of insulation from each end of the wires.
Step 3: Soldering the connectors
The temperature probe doesn't need any real installation- just plug it in and attach the sensor to whatever you want to measure, so very quick and easy. The voltage probe does need to be hard wired into the aircraft's electrical system. I decided to make a removable wiring harness so I could easily move the TM1000 and voltage probe from aircraft to aircraft.
Making a custom harness is very easy for anyone who is capable of soldering their own EC3 connectors.
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| Voltage Probe, as from Spektrum |
Step 1: Cutting the wires
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| Wires, cut to length |
Step 2: Trim the insulation
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| Roll cutting |
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| Insulation trimmed |
Step 3: Soldering the connectors
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| Set up in 3rd Hand Tool |
You'll have to choose which end of the wiring harness you want your sensing wires to go. It doesn't matter if it's the battery end or the ESC end. Just take care to make sure your polarities are all correct, if they aren't you can easily fry your ESC, TM1000, battery, etc.
A third hand tool really comes in handy here. It's a bit tricky to solder both the power wire and the sensing wire into the connector at the same time. In the photo above you can see both wires inserted into the connector before soldering. I like to hold the soldering iron on the outside of the connector, wait for everything to get hot enough, then feed the solder into the joint. It also helps to put a bit of soldering flux on the wire tips.
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| Finished connector |
Once the connector is soldered, press it into the EC3 plastic body. There are plenty of online videos / guides elsewhere to show how to do this in detail. Repeat for both wires.
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| Harness with one end complete |
Before I attached the connector to the other end, I chose to put a bit of heat shrink to act as a strain relief.
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| Completed harness, ready for installation |
Friday, April 27, 2012
Digital Niterider to LIPO conversion
I have a few old late 90's vintage Niterider Digital Head Trip units that I'm still using occasionally for commuting. One has the original NiMH battery, one has a home-made NiMH setup. This works fine, but both battery packs are super heavy and outdated by the newer Lipo batteries that are available. I have plenty of 11.1volt LIPOs around for flying electric RC planes, but unless the voltage is lowered to something my old 6V Niterider's expect, the vintage lights will go up in a puff of smoke.
My first go at making an adapter didn't work, see this post. The original UBEC I chose didn't output enough voltage, so the head unit thought it was dealing with a flat battery.
So, I ordered a UBEC from hobbyking that outputs 7.2 volts, for a low, low price of $5.04 + shipping.
I finally had a few minutes to solder up the new UBEC and see if it works... For a cable, I cut the wires off of an old and dead Niterider pack. If you don't have that available, you can go to Radioshack and pick up some DC power connectors and make your own cable. Just be sure to bring your head unit with to make sure you get the right connectors. Also take care to get the polarity right.... otherwise you'll have more smoke!
Make sure to place any heatshrink you want to use on the wires before you solder them together!
There are plenty of good tutorials on youtube on how to solder EC3 connectors. It's quite easy once you've had some practice.
Before I placed the heatshrink, I tested the system out:
The Niterider head unit battery gage showed a full charge. That's good, but with this conversion the battery gage won't really work, it'll read full until the second the UBEC shuts down. Make sure to be aware of your expected battery life and plan accordingly, because you'll have no warning when this happens. There are nicer UBECs available that do have a LIPO battery gage, you could easily use one of those.
My first go at making an adapter didn't work, see this post. The original UBEC I chose didn't output enough voltage, so the head unit thought it was dealing with a flat battery.
So, I ordered a UBEC from hobbyking that outputs 7.2 volts, for a low, low price of $5.04 + shipping.
I finally had a few minutes to solder up the new UBEC and see if it works... For a cable, I cut the wires off of an old and dead Niterider pack. If you don't have that available, you can go to Radioshack and pick up some DC power connectors and make your own cable. Just be sure to bring your head unit with to make sure you get the right connectors. Also take care to get the polarity right.... otherwise you'll have more smoke!
Make sure to place any heatshrink you want to use on the wires before you solder them together!
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| Soldering UBEC output to Niterider cable |
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| Niterider connection on the left, EC3 battery connector on the right |
Before I placed the heatshrink, I tested the system out:
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| Let there be light! |
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| Finished adapter |
Tuesday, April 24, 2012
Radio Glitch
Lesson: Never ignore glitchy radio behavior!
My new DX8 radio failed earlier this week- it suddenly refused to connect to any receivers and wouldn't re-bind even after multiple attempts. It's sitting in a box right now waiting to get sent back to Horizon Hobby for service.
So, rather than waste a beautiful still evening after completing the night's yard work, I bound my DX5 to the Icon and walked down to the lake for a few flights. At the end of the second flight I bobbled a landing, and cartwheeled the aircraft across the water. No apparent harm- but just before takeoff on the next battery the elevator channel started behaving very strangely. I pulled the model back to shore, disconnected the battery, and reconnected. It seemed to be fine.... Rather than call it a day to let everything dry out thoroughly, I taxied out for another flight. After a couple circuits around the lake, bam! It went to full down elevator, and into the water it went.
The gorilla glue is curing right now, but the next flight there will be no ignoring any odd behavior. I also have the electronics soaking in a glass full of Corrosion X. Hopefully that'll also help prevent any future problems!
My new DX8 radio failed earlier this week- it suddenly refused to connect to any receivers and wouldn't re-bind even after multiple attempts. It's sitting in a box right now waiting to get sent back to Horizon Hobby for service.
So, rather than waste a beautiful still evening after completing the night's yard work, I bound my DX5 to the Icon and walked down to the lake for a few flights. At the end of the second flight I bobbled a landing, and cartwheeled the aircraft across the water. No apparent harm- but just before takeoff on the next battery the elevator channel started behaving very strangely. I pulled the model back to shore, disconnected the battery, and reconnected. It seemed to be fine.... Rather than call it a day to let everything dry out thoroughly, I taxied out for another flight. After a couple circuits around the lake, bam! It went to full down elevator, and into the water it went.
The gorilla glue is curing right now, but the next flight there will be no ignoring any odd behavior. I also have the electronics soaking in a glass full of Corrosion X. Hopefully that'll also help prevent any future problems!
Monday, April 16, 2012
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