Scratch Built Front-steering Tricopter: The Stinger

[Beaver5150]

I'm new here, but Ive been on other forums and in the hobby for over 10 years. This is my 3rd Multi-rotor build in a few months, each one morphing into the next.
This one isn't pure scratch, but made from an Eachine tilt rotor 180 frame and parts of a wrecked MSH Mini Protos 450 heli and are spliced together at the mid section. The motor mounts are from a Tarot Ironman 450 quad, and the landing skids are MSH.
Electronics consist of AR6200 Diversity 6ch Rx, an older Illuminati32 (Naze32/F103) controller on Betaflight, Castle 25A ESCs, 2- T-Motor 1806/2300kv motors up front on the steering arms, and a single 2206/2300kv on the tail, Gemfan 6042 x 3 props. . Steering and "bomb/cargo release" servos are F.T. ES08AII. I plan to upgrade to 25mm or 28mm motors and 7 inch props soon.
Programming the controller was a pain as I'm new to Betaflight, and the default configuration profiles wont automatically assign the proper servo outputs. I had to research and enter the proper CLI commands to get it working.
The Stinger started as an experiment, but after putting a few flights on it, I've decided to keep this one for awhile. It flies like a mix of helicopter and a quad, with a little airplane thrown in there somewhere. I have nearly 2 solid hours of flight time on it now, 5 minutes per flight on a 3S/3600mAh/50C pack, which isn't bad considering the 800g flying weight.... and that's 5 minutes of fast flying, not just hovering around. The front steering works perfectly, no yaw problems whatsoever.
The LEDs are generic 12V strips and are necessary as I do most of my flying after dark due to my work schedule. This tricopter is a blast to fly at night, ripping around looking like a small UFO!
Well, there it is. I'm including pics now, and will have video soon. Questions are welcome.

 

[Beaver5150]

One of the 1806 motors up front died mid flight last night, no damage after a 50ft drop!
I installed 3 big 2816/850Kv motors (Dji type?) and 9.4x5 props for now to evaluate the performance. This is, after all, close to a 450 size copter. After some re-tuning of the PID settings, Stinger is acting like a different animal and is much more quiet. A few more sessions of tune and fly should have everything set and ready for weight lifting tests.

 

[Beaver5150]

All is well so far using the 2812 motors and 9 inch props, but I don't like the reduction in responsiveness despite pid adjustments. Stinger was much more agile with the original 6 inch setup, but those 1806/2300Kv motors were worn out when they were given to me, and undersized for a 1000g model. I have ordered new 2807 Emax motors to go with the 7 inch props Ive been saving. 7 inch is what I wanted in the first place.
I had an issue with signal drop, the Stinger has survived two falls from over 50ft and taken only minimal damage.... 10 minute fix kind of damage. I have installed a dual Rx Diversity radio since.
I plan to upgrade from the F1 naze32 clone to at least an F4 or F7 flight controller. The F1 just doesn't support all of the features I want, like GPS.
The Stinger has flown with a 20 oz. bottle of water hanging on the drop hook, and it didn't seem to have any issues so long as pid tuning was stable. Drop hook functions perfectly.
I did get a night video in a couple weeks ago. Most of my flying is usually as fast as in the video.
Fly it like you stole it!

 

[Tench745]

When I saw "front-steering" I thought you had build a tricopter with the single tilt rotor in front. Your system looks quite elegant and robust; I like it.

 

[Beaver5150]

When I saw "front-steering" I thought you had build a tricopter with the single tilt rotor in front. Your system looks quite elegant and robust; I like it.

yeah, split-tilt rotor front, but was inspired by original QX-180 front/rear tilt rotor frame since most of the hardware looked to suit my mods. I took a gamble on the front rotor steering having more yaw control/authority, and so far its paying off.
I'm about to install the new 2807 motors as we speak.

 

[LitterBug]

Very interesting! I have a few too many tricopters myself and built a front steer a while back using two of the Impossible Tilt mechanisms, similar to the RCExplorer tilt mech. I like your setup! Really need to get my tri fleet back in the air.

 

[Beaver5150]

The new 2807 motors and 7 inch props worked perfectly! The Stinger is more agile and even looks and sounds mean. I have some fine-tuning to do, but that's expected.
more pics and vids coming soon.

 

[Beaver5150]

Latest pics with 2807's and 7's installed. The last several flights have been nice and fast.
If anyone wants a more detailed photo than the ones here, or other info.... just ask.

 

[Beaver5150]

Stinger still flying well on 2807/1700kv/7x4.5x3.
I will be adding some ws2812b LEDs for voltage monitoring and mode indicators.
I haven't been tinkering with this one much lately. Been busy with the Mongrel, and Stinger flies fine as is for now.

 

[Beaver5150]

I spoke too soon. Went to activate RGB-LED function on the FC, and it locked up (brick). Now I have to do a heart surgery.... Remove FC, open, bridge bootloader pads on board, re-flash firmware, or replace with a newer FC. The one I'm using is "Naze32/F101" so it's long outdated to the point I had to retrograde Betaflight firmware to use it. I'll have to upgrade anyway before I can use the GPS module I have.

 

[LitterBug]

D'OH!

 

[Beaver5150]

After several flashings and attempts to activate rgb (ws2812b) LED output without results, it seems I've found another limitation of this F1 FC. No LED out on this one.

I did however, manage to get more experiances with CLI commands in setting up for servo/motor outputs. I also found a few tricks for putting Dif-thrust on twin motors for Mongrel.
I activated the camera gimbal servo and installed a grill/headlights/soon to be camera base in prep for Fpv/Osd experiments. I already have cam/Tx, but I need to reconfigure for gimbal mount. I may mount it underneath and run a separate pushrod for gimbal leveling on same servo. I'm not sure yet. Will also use same channel to control bomb release when I re-install that...... 4th of July coming yunno.
On the same channel, I made a 2-way 5v LED switch out of a worn out servo's circuit board to toggle between landing lights and headlights depending on whether or not Stinger is level or pitched forward flight. The headlights stay level since they are on the grill.
If this FC can't do what I want it to do, I'll make it do everything else it can do till I replace it with an F4-F7 that will do what I want. Compass, GPS, sonar, Ws2

I went back to 2812/850kv motors and big props. Those 2807/1700kv/3x4.5x3 motors and props seemed like they were drawing more amps than I expected compared to the bigger motors. Oddly enough, the PID settings fell into place easily and I only had to configure 3 times to get locked in.
Waiting for Lipos to charge.
Will get demo video of the auto switching lights this evening.

 

[Beaver5150]

Stinger went down. Seemed to be yaw servo failure from what I saw in the video. No major damage aside from broken yaw and gimbal servos so far. Yaw servo was a FT ES08aii, and I've actually had good luck with them on planes, but not "helicopterish" things that occasionally have to absorb high torque transients. The steering servos I'll be ordering will be some good solid metal gear servos for Stinger and the 450 heli I'm about to re-fit.
So that's 3 falls so far from 50+ ft, with only minor damage repairable within an hour or so. I'd say that proves that Stinger is a durable airframe.

 

[Beaver5150]

Well, I tried another yaw servo from my pool of remnant parts, just to see what's what..... The thing flew, but the yaw was not locked in. I need a metal geared servo equivalent to the ES08aii servo. It was working perfectly, but the plastic gears, the small output spline and flimsy servo horns don't do the servo justice. Crash damage revealed a servo-horn split that could have been before or after the crash. I did notice a yaw twitch The night before, but figured it was the 30mph wind screwing with the FC momentarily. The gear-lash (slack) on the ES08aii servo is remarkably tight and precise, they just can't take high torque (helicopterish) transients. Otherwise, for planes, no fails so far, I don't have a problem with (EMax)ES08aii servos, FT versions or not. They served me very well on the FT-Explorer plane I flew for awhile under some hard flying, and are still working flawlessly on Mongrel, transplanted from the FT- Explorer.
Still have yet to settle on a permanent replacement yaw servo. I'm not putting Stinger up again till I get the right one. I don't like watching her fall 50ft even if she can handle it.........it's just wrong!!

 

[Beaver5150]

Trigger pulled on new F-7 flight controller, one actually capable of running GPS and a few other peripheral devices that I intend to use. Built in Baro, dual gyros, dual camera switching, plenty of "uarts", etc. It's in the mail. Price seemed reasonable, only hope quality is up to par. It's a 30x30 board, which I prefer over 20x20 for heat sinking properties. Im not a fan of micro-technology trying to handle high current loads even if it's below 5A.
Still shopping for better servos, I need to match the specs of the ES08a2 with a metal geared and slightly stronger servo. I'm in no hurry, I'm currently busy rebuilding Mongrel, and I don't want another 50ft drop on Stinger due to another weak servo. I'll have a servo on the way within next 24 hours though.

 

[LitterBug]

Trigger pulled on new F-7 flight controller, one actually capable of running GPS and a few other peripheral devices that I intend to use. Built in Baro, dual gyros, dual camera switching, plenty of "uarts", etc. It's in the mail. Price seemed reasonable, only hope quality is up to par. It's a 30x30 board, which I prefer over 20x20 for heat sinking properties. Im not a fan of micro-technology trying to handle high current loads even if it's below 5A.
Still shopping for better servos, I need to match the specs of the ES08a2 with a metal geared and slightly stronger servo. I'm in no hurry, I'm currently busy rebuilding Mongrel, and I don't want another 50ft drop on Stinger due to another weak servo. I'll have a servo on the way within next 24 hours though.

I bought BlueBird servos for all my Tricopters which is what David Windestål used on his kits. HobbyKing had some Turnigy branded built for them too which were just as good. Never had one fail for anything other than a drop from about 100' onto blacktop landing square on the tail servo. Just bent the output shaft and cracked the top bearing mount.
This was one of the slower ones:
https://hobbyking.com/en_us/turnigy...-heat-sink-ds-mg-servo-3-9kg-0-13sec-16g.html

Also used those on my bicopters. Direct drive pivot mounted to the servos.


Here's a sample of my fastest tail setup on my stupid crazy fast beast tricopter.

My dual tilt tricopter started life as a bicopter. Had ducts on it in this video.

 

[Beaver5150]

I bought BlueBird servos for all my Tricopters which is what David Windestål used on his kits. HobbyKing had some Turnigy branded built for them too which were just as good. Never had one fail for anything other than a drop from about 100' onto blacktop landing square on the tail servo. Just bent the output shaft and cracked the top bearing mount.
This was one of the slower ones:
https://hobbyking.com/en_us/turnigy...-heat-sink-ds-mg-servo-3-9kg-0-13sec-16g.html

View attachment 224983

Also used those on my bicopters. Direct drive pivot mounted to the servos.


Here's a sample of my fastest tail setup on my stupid crazy fast beast tricopter.

My dual tilt tricopter started life as a bicopter. Had ducts on it in this video.

The ES08a2 servo was plenty fast while it was working and had very little to no gear lash at the output. The plastic gears, small output spline and flimsy servo horns I suspect are what failed. 0.8 to 0.10 second speed does well with linkage ratio near 1:1 to both front arms. Heading hold was always good and solid. Only when the servo failed (I think) did Stinger twitch and then spin-out. I was going to go cross town and look for an ES08MD or an ES09MD (dual-bearing) servo at the HS, but ended up busy today.
I'll have a look at that link you posted.

Btw, nice work on the Tri, and the bi-copter. I've come close to building a bicopter, similar to the Scorpion copters on Avatar. Now that I know the tricks to reassigning the motor/servo outputs in Betaflight (CLI commands), I probably will one day.

 

[Beaver5150]

I finally put a metal geared servo on Stinger. It seems to be working fine so far.
I ended up using SG90 electrics in a MG90S casing and gearset.
I've been busy with Mongrel lately, so Stinger was on standby.

 

[Beaver5150]

I'm at an impasse, I can't make up my mind whether or not to put the new (cheap) F-7 controller on Stinger or not. I've been slowly soldering on bits of wire and have installed the GPS and Magnetometer sensors and generally setting the thing up for bench testing and programming to get the thing figured out before I bother actually using it on Stinger or possibly Mongrel. I did get ahold of an ultrasonic "sonar" sensor, but after reading up on that, it seems they only work well over hard surfaces, so I may skip that part. The new F-7 board has a barometer. The main problem will be figuring out the output mappings in the CLI commands to set the thing up for Tri-copter per whatever output pads I have on the board. I had to go through the same process to get the old F-1 (naze32) processor to run Stinger as it sits/flies right now!
If I don't use this F-7 on Stinger, then I'll use it on Mongrel.

 

[Beaver5150]

That's it! One too many random drops from altitude..... this time, right on the house, fortunately not a tree as usual.
Front arms trashed, frame tweaked......

Stinger is about to grow wings and become a Phoenix...... for real.
Will post final damage photo later.