Wednesday, August 26, 2015

Teksumo Build Log 01

Finally! After 10 days, my order from Hobby King arrived here in Vancouver. Surprisingly, it was sent out from Singapore, not Hong Kong. But whatever, it's here and I'll start the build (hopefully) on Thursday, as I am attending the Vancouver Houdini User Group tomorrow!

My toys arrived in a largish box, with the Teksumo in its own box at the very bottom, and the rest of the parts were firmly surrounded by little air bags in the middle of the box.

Let's take a quick look at the Teksumo.

I can't wait to glue her together. Next up let's take a look at some of the other parts that will make up the build. The servos are Corona 929MG servos. These were chosen because of the metal gears used inside. Supposedly, it's really easy to strip the plastic gears in the servos of flying wings when "landing", so several people have recommended running metal gear'd servos. Not bucking that trend!

Ah, the motor. There are simply too many choices and suggestions available. I picked up the Turnigy Aerodrive SK3 - 2826-1130kv. Being my first build, I have no experience with choosing brushless motors. The general idea though, is that lower kv motors (kv indicates how many rpm the motor will spin per volt without load) have higher torque and can spin a bigger prop, while the higher rpm motors that draw the same amount of power should use a smaller prop.
The motor is elegant, shiny and just needs to be caressed. The motor arrived in it's own little black glossy box, with the insides padded out with foam. In side, apart from the motor, contains two prop adaptors, the motor mount, as well as the mounting hardware.
This motor appears to have two configurations; by attaching the prop onto the shaft, the bulk of the motors weight is now moved forward - for a flying wing anyways. This is probably the configuration I will use, unless the plywood mount on the Teksumo doesn't allow it.
The alternative configuration is to have the prop directly mount on the outrunner. I feel this is not a good idea as the prop adaptor here consists of 3x M3 screws that connect to the outrunner's bell. Not a structural engineer, but I feel this is a weaker option of the two, and the mass is now pushed further back.

I say this now, but I've not yet attached all the electronics; I may end up running the later configuration to get a good center of gravity (COG). Next up is a speed control. While the chosen motor is rated for a maximum of 13A on paper, the engineer in me says best to have a higher upper limit, hence the 30A choice vs a 20A speed controller. It weighs somewhat more, so we'll see. The ESC does not have plugs attached on the battery/motor end.
Propellers! Again, no idea which prop will fit which best, so I've bought a smattering of props from TGS and APC, in 8x4, 7x6 and 7x5 options.
Next up, is some connectors. The orangey XT60 connectors on the left are what's used on the larger capacity Turnigy batteries, so additional sets are needed to get the ESC to work with them. The right side is some 3mm bullet plugs, which is what's attached to the brushless motor, and I will be soldering 'em to the motor end of the ESC as well.
Other parts I bought to help include a prop balancer, a power meter, and a tiny OSD for when my camera arrives.
I'm still missing a few things, and I hope they will arrive in a few days. First up, my receivers! I bought a LemonRX DSMX receiver with it's satellite straight from the source in Taiwan, and it's almost two weeks, hopefully it won't take too long to arrive as I can't really test my ESC or motors without a receiver!

Various glues are required as well:
  • Amazing Goop: To join the wing halves
  • Loctite 242 Blue for any metal/metal screw contacts
  • Wellbond: Bought on a hunch that it may be useful for wood.
  • Gorilla Super Glue Gel: Already had it to repair my other planes/helis.
Batteries have been mentioned in an earlier post; I got 3 Turnigy Nano-techs, each having a capacity of 2200mah.

FPV gear wise, I am still waiting on the camera to arrive from Banggood. It _should_ work with the lcd rx I have. Fingers crossed!

And, I think that's it! I will be building the Teksumo for pure line of sight (LOS) flights first. Once I've gotten used to it how it performs, then I'll put the fpv gear on.


I've also bought an additional motor, the FC 28-12. This motor runs much faster than the SK3, at 1534kv. However, in my newbieness, I did not know that I was also supposed to purchase either a prop adaptor or prop saver to use with the motor; unlike the SK3, it did not come with any equipment to mount the props.

Crashtesthobby reports running this motor for over half an hour, so I'm hoping that either this or the SK3, with it's relatively low power needs, will give allow me nice long flight times with the props I have.

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