Mustang7302's Racing Mini Quad Build

[Mustang7302]

Hi Mustang,
Nice design should be great for racing I hope.
I might be printing a frame soon, so what's the reason you went with ABS over PLA?

PLA is strong but brittle, it doesn't absorb shock well. ABS absorbs shock better before breaking. Most importantly however is that PLA will warp/deform if left sitting in the car during our summer heat (which gets up to 105*F/41*C pretty commonly), where as ABS does not.

 

[Mustang7302]

What about a tiny secondary camera and a video switch? You can have one camera setup at 35 or so degrees of tilt (motors + camera) and another with 0 degrease of tilt for lending and taking off and flying slow.

This:

http://www.ebay.com/itm/weight-1-gr...694?pt=LH_DefaultDomain_0&hash=item4187ff546e

Plus This:

http://www.ebay.com/itm/3-Channel-3...555?pt=LH_DefaultDomain_0&hash=item4873b53c1b

I couldn't find right away a 2-way switch, but I am sure one can be found, to make the setup smaller. By removing those pins and direct soldering you can probably drop the weight for the whole setup to about 5 grams or so.

- Bogdan

PS: I think that camera I linked can be upgraded with a wide angle lens from 808#16, I am not sure, but I have seen it somewhere. It will make it 2 grams heavier though.

It is an interesting idea. However it means finding a spot for two cameras on a platform which already had very little real estate for putting stuff. Plus the extra wiring and load on the regulator.

After CR's mention of a tiny servo, I recalled seeing the tiny servos on crafts like the Blade CPX Heli or UMX Super Cub. Poked around on Amazon and found this little guy: 2.0-Gram Linear Long-Throw Servo. I ordered one and will be redesigning the top plate to have a mount for the it and make the camera mount tilt forward and backwards. It isn't much of a weight penalty and it shouldn't put too big of a load on the 5V regulator.

 

[Mustang7302]

Progress has been slow on the build this week, however last night I took the time to solder up the KISS ESCs. They fit nicely on the boom and I am happy with how clean the wiring turned out. I even got lucky by nailing motor direction correctly on the first try, even though I wasn't paying attention!

The two gram servo should come in today, so I will probably be spending some time in SketchUp tonight designing the changes for a tilting camera mount and a servo mount on the top plate. Depending on how late it gets I will get the parts printed tonight, aim to finish the build tomorrow night, and get the new craft flying this weekend.

 

[cranialrectosis]

Can't wait to see this one fly, Mustang!

 

[Mustang7302]

Speaking of seeing the new build fly... I will never put a Mobious on board to capture video because there is no good place for it, it would only ever see the ground whiz by, and I wouldn't carry the extra weight in a race. Getting video from the ground only is decent to see when you're flying low and close, which will only ever be for moments at a time.

A local buddy picked up the FatShark Dominator V2 goggles not too long ago and I have had a chance to try them a few times. Even though they're the same resolution and field of view as the Attitude SD V2 goggles I use now, I find the optics and screens to be -just- noticeably nicer on the new Dominator goggles. The biggest selling point though is that they have a built in DVR. So I just ordered a set from ReadyMadeRC and hope to see them come in on Saturday, just in time to go flying on Sunday.

 

[Twitchity]

I had never thought about using those little servos for a tilt mechanism for the camera. I have my old Blade MCPX that I don't fly which has a few of those servos... I may have to experiment with them as well. I'm excited to see some footage of this quad racing around the track.

 

[x0054]

Mustang, those servos look like a really good idea. I kind of like them for my own design as well. Do you think you could post the whole diameter and distance whole to whole for the mount wholes, once you get it? I want to see if there is enough space on my quad for one of those. If there is, I want to try making a tilt mount as well.

Also, I was looking at your 3D printed design, and I had an idea. What about designing the arms with a 2 or 3mm diameter whole through the center of the arm, going length vise? Then you can insert a 3mm solid carbon fiber rod through the center and epoxy it in place. It should make it a bit tougher, though, who knows. I don't know much about 3D printing, so I am not sure if that's possible.

In any case, looking foreword to seeing some flight videos of the quad from those Dominators.

- Bogdan

 

[Mustang7302]

Downloaded the Cleanflight utility and flashed the Naze32 last night. The Cleanflight utility looks and works a lot like Baseflight, which is great for a minimal learning curve. Setup for features and settings was a breeze. Turned on OneShot125, PPM Input, VBAT Monitoring, Telemetry Output, Servo Gimbal, set Angel Mode, set Horizon Mode, set Aux 2 to Servo Pass through. I then set a baseline tune with the following settings:

Min Throttle: 1030
Max Throttle: 1970
Min Command: 1000
RC Rate: 1.10
RC Expo: 0.10
Throttle Mid: 0.30
Throttle Expo: 0.35
Pitch & Roll Rate: 0.60
Yaw Rate: 0.80
TPA: 0.40
Looptime: 2000
Pitch & Roll P Gain: 3.2
Yaw P Gain: 6.0

I did have one of the KISS ESCs let out a puff of smoke the first time it powered up and was exceptionally warm. This was one of the KISS ESCs I received from Cranial and wasn't terribly disappointed when one was bum. Luckily I have had a spare ESC laying around from the Twitchity Acro quad build, so no real issue there.

At this point the build was ready for a maiden, but I found vibration to be wildly problematic when armed and throttled up on my desk before I got around to putting props on it. The studs which the FC were mounted to are under tension and acted like a huge tuning fork resonating vibration. When I took the FC off the studs, put nylon stand offs in its place, and used o-rings on either side of the FC's mounting holes, the vibration was no longer an issue. Now I have an issue where the FC is sitting about 15mm higher than I had planned. It not only looks bad, but leaves the RC flopping around, and might cause some clearance issues with plans for mounting the FPV camera. It looks like I might be replacing the 30mm and 35mm aluminum screws with something in the 20mm ball park and need to source some shorter nylon stand offs. So close, yet so far...

The two gram servo looks like it works like a champ. It runs great off of 5V, has minimal chatter, and looks to have about 3/4" of an inch of linear travel. I will have to fiddle with the geometry to give the servo a mechanical advantage to swing the camera +/- 25* of travel.

x0054, I will get the dimensions up for you tonight when I get home.

 

[cranialrectosis]

Can you use the studs and put a nyloc under the board and make an O ring sandwitch between nylocs to hold the Naze in place on the original studs?

 

[Mustang7302]

Can you use the studs and put a nyloc under the board and make an O ring sandwitch between nylocs to hold the Naze in place on the original studs?

The PCB, RX, and FC made a sammich of components which leaves the mounting holes to the FC unsupported. The studs were also not perfectly aligned due to 3D printing tolerances, which meant one or two were pushed into alignment putting the board under tension. Even if I did have supporting stand offs which accommodated o-rings above and below with these long studs, the board would still be under tension. By using a stand off, nylon screw from the top, with a o-ring sammich, it takes the tension off the FC by getting it up and away from the studs.

I've got an order in to Amazon for some 20mm M3 screws which will come in tomorrow. I will 3D print my own FC standoffs just tall enough to clear the RX between it and the PCB. Then I can address plans for the camera mount.

Oh, and then there is the bit about taking out the 30mm screws without taking -everything- apart for the new 20mm screws...

 

[Mustang7302]

Do you think you could post the whole diameter and distance whole to whole for the mount wholes, once you get it? I want to see if there is enough space on my quad for one of those. If there is, I want to try making a tilt mount as well.

Hole Spacing: 14mm x 15mm
Hole Diameter: 1.25mm

 

[x0054]

Hole Spacing: 14mm x 15mm
Hole Diameter: 1.25mm

Thanks! That's so tiny. It fits very nicely in my design. I am ordering one. Looking foreword to seeing how you do your mount.

 

[Mustang7302]

Orange Scream flies! But I will get back to that.

The new 20mm stainless screws came in on Saturday, it was a pretty easy swap to remove the 30mm aluminum inner set of screws (didn't even need to take everything apart). I 3D printed a set of 7mm stand offs and used a steel screw to thread the ABS (used a 1.45mm radius for the interior hole). These standoffs were the perfect height to sandwhich the RX between the PDB and FC, while allowing enough depth for the 20mm screw and a 8mm long screw with o-rings to secure the electronics stack. With those dimensions finalized, I could finally draw up a top plate to protect the FCB and have a place to mount the servo for the tiling camera.

The geometry for the tilting camera has been a pain to get right. I must have printed four sets of parts adjusting fit and the linkage alignment. I have actually gotten to the point where I think I will abandon the pivoting mount and go back to a 20* static mount because it has been that much headache and I am not thrilled with just having the servo sitting on top of the center stack. To take a break from the fiddly work on the pivot, I decided I would go a head and get the thing in the air and see how it feels.

We had pretty high winds almost all weekend long here, so the maiden hover took place in my living room. Once I put props on it, it took at least six or seven PID adjustment attempts to get the high speed oscillations dialed out of it for the first hover. Getting it to take off on its own went well, but boy is there a lot of "fighting" those tilted motors. Flying in auto-level mode it takes a lot of back pressure hold a hover. After hovering for a minute or two, I set it down and noticed that the tilted motors wanted to make the thing scoot forward across the wood floor. Amused by this, I "drove" the quad around the floor for a bit using yaw to steer. It was fun, but the dog was not amused.

Here is the new baseline settings after the maiden:

Min Throttle: 1030
Max Throttle: 1970
Min Command: 1000
RC Rate: 1.10
RC Expo: 0.10
Throttle Mid: 0.40
Throttle Expo: 0.35
Pitch & Roll Rate: 0.60
Yaw Rate: 0.60
TPA: 0.40
Looptime: 3500
Pitch & Roll P Gain: 1.4
Yaw P Gain: 4.0

It came in at 350 grams plus the battery, which is awesome for the super heavy motors on it. If I had used traditional 2204 motors, it would saved 80 grams of weight. I will say though that the RPM and mass of these bigger motors seem like they're going to really drive some performance. The yaw authority was way more than expected for a mini quad and I ended up dialing down the yaw rate.

At this point I just need to wind to be calm and get it out to start doing some shake down runs on it.

 

[Mustang7302]

Thanks! That's so tiny. It fits very nicely in my design. I am ordering one. Looking foreword to seeing how you do your mount.

Due to the limited space, I ended up mounting the servo in the center of the top plate which covered the FC. When I printed the plate I put some grooves where the servo was going to sit so that hot glue would have more surface area to bite on to. The bottom of the servo is not flat, combined with impossibly small holes, I didn't want to bother with trying to screw it into the plastic.

If I was to do it again, I would probably order the 3.5 gram non-linear servo which is more in line with a traditional servo. It might help with some of the headache of getting everything setup.

 

[Mustang7302]

Two weekends ago I took Orange Scream to get some initial shake down runs on it and finish getting it tuned. Somewhere between the heavy/torquey motors, the ABS material flexing just enough, and/or vibration to the Naze I just could never get a tune on it that was a sweet spot between high speed oscillations and low speed oscillations. I had the P gains as low as 1.6, but never could get it dialed in. With a couple of design changes and a 1806 motor setup, this frame could have been pretty nice to fly, but that defeats the purpose of this project.

I had already been having discussions with Twitchity to modify my existing Acro frame with new arms which had slotted holes oriented forward to allow the motor mounting screws to pass through at up to a 15* angle. I was running out of time with Orange Scream and had asked Twitchity about getting another Acro frame since I had already had plenty of experience with it and loved the design. With only a couple of other minor changes to the design, he had the new frame delivered to me with plenty of time to get everything built for this past weekend. A huge thanks to Twitchity for being so quick and great to work with!

Between it raining -all weekend long- here this past weekend, it looks like I will be going into the race event next weekend with very little practice under my belt. This was making me very nervous and I ended up making the decision to change up the deck by erring on the side of caution. I needed setups which I could be confident in not roasting ESCs, not melting batteries, getting at least four minutes of -hard- run time, and a level of performance which will be comfortable to run with minimal practice. Here is how the deck is going to run for this first event for the year:

Spec Class Race Quad:
Frame: TwitchFrames Acro Quad w/ 15* Forward Tilted Motors
Motors: Cobra 2204 2300KV Motors
ESCs: KISS 18A w/ One Shot
Props: HQ 5045 Bullnose (Glass Composite)
Flight Controller: Naze32 Acro w/ Cleanflight
Receiver: FrSKY D4R-II w/ PPM & Telemetry
Battery: ThunderPower Magna 1300mAh 3S 70C
FPV vTX: TS5823 32CH 5.8Ghz 200mW Mini
FPV Camera: ReadyMadeRC Pico V2 520TVL
FPV Antenna: VAS LHCP Airblade 5.8Ghz
Camera Tilt: TGY-D1290P 3 Gram Servo

Open Class Race Quad:
Frame: TwitchFrames Acro Quad w/ 15* Forward Tilted Motors
Motors: SunnySky 2208 2600KV Motors
ESCs: KISS 18A w/ One Shot
Props: HQ 6045 (Carbon Composite)
Flight Controller: Naze32 Acro w/ Cleanflight
Receiver: FrSKY D4R-II w/ PPM & Telemetry
Battery: Turnigy Nano A-Spec G2 1800mAh 3S 65C
FPV vTX: TS5823 32CH 5.8Ghz 200mW Mini
FPV Camera: ReadyMadeRC Pico V2 520TVL
FPV Antenna: VAS LHCP Airblade 5.8Ghz
Camera Tilt: TGY-D1290P 3 Gram Servo

The Spec Class craft is a compromise between not going with as much power as I can throw at it and still optimizing the build for speed, minimal drag, and a good riding experience. The build came in at 260 grams, plus a battery, thanks in part to a lot of attention to making everything as refined as possible. There are no connectors any where, with everything being directly soldered and cutting wires to length. The RX is tucked away under the flight controller and the top deck (3D printed) for the camera and vTX is pretty low profile.

I found with the angled motors and a static camera facing 20* upwards, it was all but impossible to have graceful landing under the goggles. So the addition of a servo and using the Pico camera is a solution reminiscent of some of my early FPV setup tinkering. The Pico camera is a lower resolution and it doesn't have as good of a contrast range as the Sony Effio-V cameras; but it does not have any output lag, its contrast switching is still fast, and it is a very small size which makes it a million times easier to fit on a frame with limited real estate. The camera is compromise to have better usability during race time and being able to go slow for a soft landing.

Here is a few pictures of the Spec Class racer:

Getting a baseline tune on this build went very smoothly and took very minor tweaks to get it super solid in the air. I can finally comment on my impressions of using OneShot with this setup. Using the KISS ESCs before with Baselfight, the old setup was locked in and felt connected; but it was very robotic. With OneShot and Cleanflight it still is locked in and connected feeling, but now you watch it in the air and it just looks effortless. It isn't super noticeable but the difference is there.

This week I am building on the Open Class craft and will post an update on it later.

 

[cranialrectosis]

Can't wait to see this one race!

Details on how you control the servo for the camera?

 

[Mustang7302]

Details on how you control the servo for the camera?

The Taranis features four analog pots (potentiometers) which can be mapped to any channel. Two dials at the top of the face and two sliders on the left and right sides where your index fingers would just about naturally sit. One of these pots (I use the right slider) gets mapped to channel seven which feeds into auxiliary two on the Naze. Enable the Servo_Tilt feature (this changes the ESC output order) and map Aux 2 to drive the tilting servo which will then give you manual control. Finally just adjust your min, mid, and max adjustments of channel seven through your transmitter to limit up, down, and where it centers.

 

[Twitchity]

The new quad looks nice Mustang. That's also an interesting camera setup you have there. You sure didn't leave any spare room anywhere on that frame. I hope it serves you well in your races.