The first part of a detailed build is available here. This post is mostly an overview of the parts used as well as some sample flights.
Part list:
- Eachine Naze32 Brushed FC ($7): note that newer ones like the F3 will not work. (Or at least not as easy)
- DasMikro FlySky Receiver ($10): version B, for PPM output on CH8.
- Eachine 8520 Motors ($12): I'm really interested to try the RacerStar or Chao-Li ones to see if I can get a bit more oomph out of them, as currently its a bit anemic even with ladybird props. Maybe 2s?? :P
- Ladybird 55mm props ($8): works great now for the quadcopter. Have some 65mm King Kongs on way which hopefully provides more power and are considerably cheaper at $5 for 10 pairs intead of $8. There are less clearance issues on the tri compared to the quad.
- 3.7g servo ($2.50): could have gone lighter, but was the cheapest I could find on AliExpress at $2.50. The Emax 2.5g should work too (and may be better quality) but is a whopping $5!
- 1x rubber grommet ($1.50) for ghetto-mounting the tail motor to servo horn
- 3x "craft grade" popsicle sticks from the dollar store
- Prop guards ($2.30)
- Elastic bands
AUW is about 50 grams before camera.
Total was a bit over $40 without FPV stuff, with a lot of spare props and grommets, plus an extra motor (Since the tail servo handles all the yaw and the number of motors are odd anyway, the third motor can be any direction). Not super cheap compared to RTF quads available on the market these days, but I'm not aware of a tri in this price range, and it was a pretty fun build process! I would love to hear how one might go cheaper on this if anyone has any ideas! :) I expect 720 motors could work, but the cost savings would be negligible. Oh and I forgot to include the price of the battery, which was from my V222 quad...
Using FlySky i6 receiver with 10-ch mod. (swich off AFHDS 2A to bind).
Indoor flight:
While not as anemic as the initial popsicle quad with the weak triblades, its definitely could do with some more power. Hopefully the 65mm props in the mail would help. I should also consider removing the prop guards as they add a tiny bit of weight, and also see if getting different batteries would help. (These are from a unbranded multi-pack I got for my V222, and there's no discharge rating on them. Have some 600mAh 25C's coming, so will see if the battery may be the limiting factor here...)
*update* the 65mm props have arrived, and there's a lot more thrust now! Check it out:
And some flight footage:
*update2*: Yet another outdoor video with the 65mm props:
This time I had a larger area to play in and was able to fly a bit harder. It flew well generally, but I'm finding that the props are a bit loose and pop out relatively easily (this could have been after an incident where I crashed it indoors while tuning perhaps)... by the end of the second pack, I had lost the tail prop in flight and crashed it such that one of the main popsicle sticks have unglued... luckily all electronics appear to be intact. back to the workbench!
Bonus pic the happy DIY multicoper family (so far):
3 comments:
You said "any direction" for the yaw motor... I'm sure you know as long as the spin direction matches the motors spin direction so the brushes don't bind from spinning backwards.... others might not know that though. I had a u807 that came with motors wired in reverse spinning backwards and they failed in a few flights one right after the other. Replacement motors never failed with at least 5 hours use and still working well. I've had great luck with small coreless motors.
BTW was looking at 8520 props to find this... about to order the larger King Kong 65mm props you used. Not sure why they would put 55mm 7mm motor props on 8.5mm motors with similar KV. Thanks...
@John, thanks for the clarification in your first comment. Yes, what I meant was that you can use either a CW or CCW motor but it should be wired correctly with the + and - hooked up accordingly. Otherwise they will spin in the opposite direction but as you mentioned, will drastically reduce life of the motor.
For the second comment, I think both 65mm and 55mm props *could* work for 8mm (8520) motors, and 55mm will mean cooler operation but slightly less thrust (assuming other things like blade pitch is the same). for 7mm motors 65mm is probably a bit too much. it also depends on whether you use 1s or 2s, as most of the 8520 ones will often in practice work with 2s (even some that are rated with 1s) and i would use smaller props in that case. either way i expect life to be reduced as it will heat up a lot more... so probably best to just stick with 1s. the good thing is brushed motors are pretty cheap these days so its not too $$ to experiment. i've been more interested in brushless builds now and there's some interesting 110x, 130x and 140x options for quads not much larger than these brushed counterparts. would be fun to build a micro brushless tri using 110x running on 2s for example!
Finally, another thing to note for the King Kong 65mm props: the hole is actually a tad larger than 1mm and is much looser compared to the 55mm ladybird props. I've had them fall out during aggressive manoeuvres (esp the tail prop on the tri which does a lot more work when pitching forwards). The easiest solution is to add a bit of dental floss on the motor shaft - you may have seen this tip from other sources online... :)
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