Sinister 770 Quad Build

[Graham Lawrie]

That is one of the best explanations i have read Paul:) great work:)

[Derek]

There are times that Paul just over powers me with his explanations.....but i think i understood most of what he said lol

[Derek]

Finally, here is a picture of my the Sinister 770 Super Class Quad. My daughter, who has proven to be a valuable Crew Chief, requested a photo op....I can't deny her that, lol. She has help quite a bit during this build by sanding parts and tightening screws (as well as losing a few, lol).

Sinister 770.jpeg (256.53 KiB) Viewed 5010 times

[DOG]

Good luck with your next attempt Derek We're all pulling for you

[pvolcko]

Damn that thing is big.

What motor's and props are those? Hard to believe they're in the 24A current range of those ESCs.

[Derek]

The motors are T Motor 3520 400kv with 15x7 Master Airscrew 3 blade props. The specs for the motors state a max amp draw of 28 amps on 6S with 17x8 props. Im running two 6S packs, in parallel, with 15" props on 40 amp, 6S capable, Little Bee esc's.

No, it won't be the fastest thing at the field but it should be an "eye grabber."

[pvolcko]

Hmm. specs seem okay. Hopefully just a bad ESC. May want to check the motor it was on to see if it has any shorts from the mounting screws or something. Can't believe those little things can handle that kind of current and power.

[Derek]

Checking the motor mount screws was one of thr first things i checked (previously learned lesson). There is lots of room between the screw tips and the windings.

Paul...you were saying something about not believing "those little things" can handle that kind of current and power.

Are you talking about the motors or esc's? The motors arent very little, at all. Quite beefy. I'll get a link to the motors and the esc's and I'll share them. That way you guys can check them out.

[Derek]

Here is a link to the motors that I used:

http://www.buddyrc.com/t-motor-mn3520-1 ... motor.html

Here is a link to the esc's that I used:

https://www.helidirect.com/littlebee-40 ... ot125.html

I needed a low kv motor that would handle 6S. These T Motors are rated for 8S. I can't get the images on that page to load up, right now, but if I remember correctly, these motors will pull 28 amps on 8S with 17" props. I'm set up for 6S on 15 props, with enough frame room for 16" props.

As for the esc's, they needed to me 6S capable...obviously. With an amp draw of 28 amps on 8S, I opt'd for for amp esc's and I found that Little Bee has 40amp esc's. I love the Little Bee esc's (Thanks Stambo!)

My new esc's showed up yesterday. I've got to work tonight, so I won't be able to work on the 770 until Wednesday.

[pvolcko]

I was speaking of the little ESCs.

[Derek]

Question time...I think I know the answer but I'd rather ask a silly question than.....well, you know, lol.

My esc's are OPTO, no BEC. I have them connected to the FLIP32 with the ground wires to the ground pins....signal wires to the signal pins. Fair enough. Now, I soldered a JST plug, from the 5v pads, to power the previous KISS FC. If I remember right, I can take that JST plug and plug it into any of the spare pins on the Motor Output side of the fc to give power to the fc, right? Or, does the JST plug need to plug into a set of pins on the RX Input side? I'm using a PPM rx setup, so there are plenty of "spare" spots to plug into.

I'm thinking that I'm right, but I've been wrong before. I'm thinking that I can plug into a spare pin set on the motor side. Am I right?

[KevG]

Yes mate just run the BEC to a spare motor position.

[Derek]

I sure do like having you UK guys on the forum, lol. It's early AM here but I was almost certain that either you or Graham were around.

Thanks Kev!

My replacement esc's showed up, the other day. I have the FLIP32 on hand. Can't sleep, so I'm in the garage doing some soldering.

[Derek]

Alright, I've been looking for info on this next topic but i'm not finding anything that really helps me out...so, its time to pick the brains of the Hangout, lol

VBAT on the FLIP32

If I'm understanding this properly (that's questionable, lol), I can run a lead from my PDB to the VBAT, with a beeper connected, and the VBAT will make the beeper "beep" when voltage is getting low. Considering that my 770 is a 12lbs craft, I'm thinking "battery voltage monitoring" could be useful.

Whats a good way to use the VBAT pins?

[Derek]

Since I had that "still unexplainable" esc fire last week, I've replaced the burnt esc with a new one (and I have two spares now, just in case). I've also added a bit of thin plastic, to act as an insulator under each of the esc. Esc's will short out of the voltage touches carbon fiber frames...my frame is not carbon fiber. My frame is wood and composite that is covered with fiberglass and then colored with black Plasti-Dip. Could my fire have happened because the esc pads were touching the Plasti-Dip? Is Plasti-Dip conductive? I'm going to say "no" because it's more of a rubber...I think. So, I dunno.....but I added the insulator anyway.

insulator.jpg (414.03 KiB) Viewed 4974 times

I've removed the KISS FC and installed a freshly Cleanflight flashed FLIP32 FC and added a new PPM cable from the fc to the rx

FLIP32.jpg (550.27 KiB) Viewed 4974 times

I got the wires all pulled to the sides with simple plastic cable clamps and I've been all though Cleanflight with the FLIP32 (3 times, just to be sure). I did plug a battery in (obviously in the Motors Tab, to calibrate the esc's) and I got no magic smoke nor flame....which is a good thing if I'm not mistaken. I've put the 770 on the floor "WITHOUT" props, plugged in both batteries, and armed the fc. All 4 motors spin with such a beautifully smooth and harmonious sound of synchronization.

I am going to go into the BLHeli Suite and double check the calibration numbers and I'm going to read up more on the protocols. I'm being told that ONESHOT125 is too fast for a quad of this size. I'm going to refer back to Paul's given explanation about protocol's, earlier in this thread and whatever else I can Google Search.

We should be ready for a hover test next week, given the fact that I'm working my usual 12 hour shifts all weekend.

[Derek]

I was just reading through my last post and I saw the picture of the FLIP32 with the standoffs on top. No, I'm not going to be adding anything more on top of the fc. On the 770, I just figured that it would be better to use some of my extra, of extras, standoffs to secure the fc in place instead of the usual small screws. Using the standoffs just seems to make it easy to reach in with my fingers and remove the standoff in order to get to the PDB, whereas using screws is a bit more complicated.

So, when you notice the standoffs on top....that's why they are there and not screws, lol.

[Derek]

I have a friend that is much more knowledgeable about PID tuning that I am. I've never had to tune a quad, lol. My Sinister 770, on the other hand....well.....lol.

My friend met up with me at my usual field today to test hover and tune the 770. We plugged in both 6S packs and stepped WAY BACK, lol. Lets face it...this machine is more than any of us had seen before and now it's got voltage running through it, lol. Armed the board and raised the throttle slowly....it does manage to get off the ground a bit with TERRIBLE oscillations and before I can set it down, the quad flips over and slams into the ground. Nothing broken, so we try again. After about 30 minutes of hovering and tuning...the 770 now is able to be flown around but still has some oscillation. We are going to meet up again this weekend for more tuning. But....the Sinister 770 Super Class quad did fly and it did go home in one piece. I'm stoked!

Dad was on hand with a video camera. I'll share some the videos as soon as I get them.

Sinister 770b.jpg (73.45 KiB) Viewed 4964 times

[DOG]

Awesome dude . Cant wait to see the video

[pvolcko]

Cool beans!

[Graham Lawrie]

Nice one:) looking forward to the video:)