March 29, 2014

Tri-copter test flights

I got the time, place and weather to test out the tri-copter the other day. I flew three batteries to adjust the PID settings on the board and try out the mobius recording from the air.

I'm still having issues with wobbling when flying forward at low prop speeds (slight descent) but from what I read I have to give up some P to get rid of it.

You can see from the telemetry data that there's good margins in the power system with burst peaks of about 23 amps while giving some aggressive cyclic inputs.


March 28, 2014

Servo connector crimping tool

The crimping tool is one of those tools you should have from the beginning. Being able to adapt the length of your servo leads helps a lot in improving your builds.

As mentioned earlier I ripped away the S.BUS decoder from the tri-copter since I expected a release of the KK 2.1++ S.BUS firmware. But it never came. Instead I set out to re-solder the servo connectors on the decoder to make the leads shorter and fit better on the tri-copter body. I have re-soldered servo connectors before and I know it sometimes doesn't work. What happens is that the solder flows into the connector and prevents the male connector from entering the female and it can't be connected properly (obviously). Soldering is an option if you don't have a crimping tool available, but since I had a lot of connectors to re-solder I figured I wouldn't succeed after having broken a few.

The other day the crimping tool from hobbyking arrived. Word has it that the hobbyking tool is good enough, but if you wan't the real deal you should get this one.

I had the opportunity to try it out and actually complete the tri-copter setup tonight. I must say the result when crimping with the hobbyking tool is so-so. It is maybe a millimeter to short and the result must sometimes be corrected afterwards.

As you can see in the picture the first connector got a bit ugly. I took it a part and corrected that after the picture was taken.

March 20, 2014

Found a fitting main shaft for the scrap 450

Having 30 minutes of spare time I revisited the scrap 450 which I knew had gotten a main shaft of the wrong length. I could adjust it with radio subtrims, but I would not have 90 degrees at zero pitch. I went through my drawers and found a main shaft that fits. Next step now is to get it hovering to check the blade tracking.

March 19, 2014

FPV250 has arrived

I got the FPV250 frame in the mail today. And with it came one ESC (silly me). Still lacking a lot of components but the receiver and camera is already in the drawer. I have ordered more ESCs from HobbyKing, motors and props from myrcmart and a cc3d controller from drotek.

Quickly checking the camera ( Fatshark 600TVL with pan and tilt ) I noticed that the servo would fit perfectly into the slot in the FPV250 frame. But some silly engineer at Fatshark probably decided to save some dollars and use a servo which has the cable sticking out the side of it. This means it won't pass through the slot in the frame. Unless you take the servo apart, which I probably will do.

March 18, 2014

F-35 ready to fly again

I finished the repairs of the F-35 EDF today. I got the hinges I needed for the rear control surfaces the other day. The ones I got are actually a bit too big, 4,5mm. It works but takes a bit too much force to my taste. If the plane had been more valuable than it is I would probably have waited a few more weeks to get smaller ones.

The ones I used this time are these 4,5mm hinges. I previously ordered 2mm hinges, but they are too small for the large holes left after all my crashing. 2,5mm or 3mm should be the best pick.

FPV250 ARF available from HobbyKing

I just saw the daily on the FPV 250 ARF package from HobbyKing. This package contains the setup of the FPV250 recommended by HobbyKing from the beginning plus some extras like a cable, pan-tilt mount, washers and bolts.

I quickly did the math and it seems not to be any cheaper than buying the parts individually, but it is definitely more practical and the props and motors have been on back-order for some time now.

To be noted is that the package contains only one of each prop, no extras. If you get a bad prop (they're cheap props from HobbyKing) or if you break one you are out of luck. Similar props are available from where they seem to be in stock.

March 17, 2014

Ordered the wrong video transmitter

I got the video transmitter I ordered from ebay last week in the mail today. Great! Much faster than expected. However, I didn't do my homework and this transmitter, Boscam TS351, does not work with my Fatshark goggles. When it's too cheap to be true, it simply isn't true.

I have now placed on order for a far more expensive ImmersionRC transmitter instead.

Almost finished 250, but no flying today

The elevator servo on my CopterX 250 died in-flight this summer and I finished the repairs yesterday evening. I replaced all cyclic servos with Corona DS929HV and the gyro with a 3GX MR. The previous setup was all CopterX parts, servos and the 3x1000 gyro with a standard 6ch receiver. The receiver was a quite clumsy orangerx and got a good deal on the 3GX MR gyro. The gyro is really small and setup is quite easy compared to the standard 3GX.

One big issue with the servos are that the elevator servo is slightly to long and the canopy does not attach well on the canopy mounting bar. I'll have to find some great solution to that.

I intended to give it a test-spin today. But the weather surprised us all and the winter came back.

March 12, 2014

S.BUS decoders

I have started getting used to using S.BUS in gyro controlled flyers (like FBL helis and multirotors). With S.BUS there is only need for one cable from the receiver to the controller which makes the setup simpler. Also, when using one of the two Futaba telemetry receivers available and picking the cheaper one you must use the S.BUS if you need more than three channels.

When collected the parts needed for the Tri-copter build I naturally picked the R7003SB telemetry receiver since even the cheapest helicopter gyros have S.BUS support nowadays and I had already stumbled upon RC911's build for the KK 2 board which supported S.BUS. However, it turned out S.BUS was not released for the KK 2.1 board yet. To solve this, you either but the pricey R7008SB receiver or you buy an S.BUS decoder. I picked the latter and installed a Corona S.BUS decoder in the Tri-copter.

However, the Corona takes up a lot of space, all the cables that is and I quickly removed it in hopes of a S.BUS release from RC911. Which never came. And now I have gotten what I thought was an alternative, the Frsky decoder. I have now tried out the FrSky S.BUS decoder and cannot make it work because I don't have a Futaba channel changer or the Frsky channel changer. I thought that I would be able to use either the Corona channel changer or my Futaba reciever, which has an S.BUS programmer built in. But it turns out it doesn't work.

The Frsky decoder seems to work like four S.BUS servos in parallel on the bus. While programming, you push the button to select one "servo" at the time to listen to the bus, and while installed they are all active. However, the "servo" does not support the full range of features that a S.BUS servo should according the specs and only supports the command for changing the channel. Using the Corona programmer in programming mode or in channel changing mode does nothing. Hooking the decoder to the Futaba transmitter only causes it to crash.

From the image below you can see why I had hopes for this decoder to be a better fit on my Tri-copter. It is really small and perfect for a tight installation. It is a simple device wrapped in a piece of paperboard with four servo PWM outputs. Some silly engineer must have thought it was a great idea to let one of the outputs point upwards instead in putting the four outputs in two rows, which would have been even better. Also, the outputs are very exposed and needs some insulation before installation.

I won't be using this product. It didn't gain my trust and I won't buy a programmer just to get this one device working. Instead, I'll be doing some cutting and soldering on the servo leads on the Corona device to make it fit nicely on the Tri.

March 7, 2014

FPV250 back in stock!

I noticed today that the FPV250 was back in stock. And of course I ordered one right away. I was also supposed to order the ESCs but made a classical mistake and ordered only one. The rest of the stuff needed was still on backorder.

I still haven't read up enough on FPV gear to decide which camera and transmitter to buy for the FPV250. I'm thinking a 200mW 5.8Ghz transmitter and a cheap and light 5V driven camera would be great.

F-35 progress

I spent some time on the F-35 today. Managed to do most of the work needed. I ripped out the old EDF and ESC. Soldered longer leads on the new ESC, added the E-FuelGauge and installed the new EDF64 and receiver. Made a mistake while setting up the transmitter and the fan started running, seems I need to read up on fail-safe with the FASST receivers.

The only thing left is one of the broken off tailerons. I have bought new hinges but they are too small. New ones are on the way.

I've added a page for the model in question.

March 4, 2014

Scrap 450 build finished

I finished the scrap 450 build today. I didn't have any good SE V2 canopies so the sharky canopy will have to do for now. Hopefully I can take for a first test flight the next few days.


March 3, 2014

Even more stuff today

Not only did the Fiji postal service deliver today, but the Danish as well. I got two more e-fuel gauges. I already have two of those and flying without them is getting harder and harder. To know how much capacity you have left instead of using a timer and to know how well balanced your power setup is is fantastic.

I plan on installing those two in the T-Rex 550 and the F-35 EDF. Right now I'm one telemetry receiver short, but it should show up any day this week.

HobbyKing service via Fiji was excellent, but...

Only one hour after I saw the hobbyking daily telling that they will stop shipping via Fiji since there has been complaints, I got my package via Fiji, to my doorstep.

I picked the cheap shipping option for this order, which normally does not include home delivery. It resulted in the Fiji shipping. Since I've heard about Fiji shipping being slow I actually ordered a few small parts again, just to get them sooner. It turns out the Fiji shipping was faster that the Singapore and Malaysia shipping. The latter usually takes 20-26 days (cheap option) but the Fiji only took 16.

So what was in the package?

A Fatshark FPV camera with pan and tilt. I haven't decided if this is going on the Bixler or on the Tri-copter. Forum posts indicates the Mobius should not be used for FPV since it is not stable enough, but firmware updates should have fixed that issue.

A HK 450 tail assembly. This is for the 450 scrap build, which is currently on hold waiting for this particular part.

3 Corona DS929HV servos. These are for use as cyclic servos on my CopterX 250. I've actually ordered Align servos from Helikraft, but I have the impression they will never show up, so I go with a cheaper option for this cheap helicopter.

And the usual extras; 14AWG wires, short servo lead extensions, screws and battery straps.