Merica 3" - All Black Theme

The First Build Attempt

This is my 3rd build and probably the most difficult one. I purchased this frame a bit ago and planned to use the Lumenier Alpha AIO FC&ESC combo in the lower section of the frame. Initially I wanted the 'Eagle' style canopy instead of the Mayday canopy in order to have a really clean and simple build. My first attempt at building this failed as the Lumenier Alpha AIO FC wasn't really as great as I hoped. It lacked in the inputs I needed as the SBUS pad was hardware inverted and it wasn't possible to turn off the inversion. I use Spektrum so this left me with only a single usable UART and I wanted IRC Tramp too. In addition it was a major pain to fit in the lower section of the frame. I had to use such a thin standoff that the battery strap was interfering with the flight controller and causing noise in the gyro. Since the AIO ESC/FC combo was a bit too bulky I also couldn't soft mount the board, so the end result was a really noisy and lousy flying machine that was frustrating to build and didn't have the components I wanted. I decided to scrap the AIO single board idea and see what else I could come up with.

I purchased the CLRacing F4S and Aikon32 ESC with the intention of using it in a 5" 6S build. However, Raceflight released their RevoltOSD and Bolt32 combo days after and I decided I'd prefer the Raceflight components in my 5" build instead. Since I had these boards already, I decided to install them into this 3" frame instead. (You can see a sneak peak of the 5" Merica w/ Raceflight in the pics below)

The Second Build Attempt

My second attempt at this build retained the Eagle canopy (it's a simple cover and camera mount that lacks the FC mounting capabilities of the other canopies). I mounted the Aikon ESC in the lower section of the frame and mounted the CLRacing FC to the top plate. The Aikon32 ESC has a rather large BEC on top so this left very little room between the boards to fit anything else. I managed to cram my receiver in there but the receiver could make contact with the FC which I didn't like. Mounting the VTX was a nightmare as the only space left was in the Eagle canopy. I eventually made it all work but it was very crammed, much too tight, and both the VTX and receiver ended up in contact with the flight controller. The end result was once again a noisy and lousy flying quad. I suppose it was 'okay' but it just wasn't the performance I knew I could get out of the components in this frame. You could hear the flutter in the motors when just hovering.

The Final Build Attempt (So far)

My final attempt at this build included the Mayday canopy which made everything infinitely easier. The FC mounts to the canopy, which is a printed TPU part already so it adds additional vibration isolation on top of the soft mounted FC grommets. The additional space created by mounting the FC in the canopy allowed me to fit my receiver easily between the FC and ESC. There was enough room to add a bit of double sided tape foam and a zip tie to securely mount the receiver so it can't move at all. The VTX is now safe and sound in the upper portion of the canopy with no room for it to move around. I haven't gone out to tune yet, but I can tell immediately just from flying around my apartment that it's significantly improved. the quad sounds so silky smooth in the air now. I think the vibration dampening in both the canopy and the soft mounted FC adds a lot of physical noise filtering which should end up in a smooth flying machine.

Some Regrets

However, there's a couple of downsides to this build. First is weight. The final weight of the completed quad is ~190grams. For a 3" quad it's pretty heavy. My 3" Ultralight build comes in at 140grams so the additional 50 grams in the quad is a lot. Obviously I've stuffed an oversized and overpowered ESC and FC into this thing where a 20x20 stack would probably be more fitting. I chose the Cobra 1407 4100kv motors because I wanted raw power, even at 14.5 grams per motor. However, I have found that the Rotorgeeks 1407 4100kv motors weigh a little less and perform just as well or better than the Cobra motors. If I had to rebuild it, I'd probably use those motors with a 20x20 stack. My estimates tell me that would drop ~22grams in total, which would make it a much more respectable weight.

Unfortunately, the frame also has it's issues on a 3" scale. The Mayday canopy solved the fitment issues but also caused a problem with prop clearance. The Mayday canopy extends a bit further up in the front and the props were striking the canopy. I had to raise the front arms to the top position in order to clearance the props to the canopy. This completely defeats the point of having the staggered arms to get clean air to the rear props. This is a real bummer as Catalyst Machineworks advertises this frame as capable of fitting 3.5" props but it can't even fit 3" props with this canopy.

All of that said, I haven't put a full pack through it yet; this thing has really powerful motors, a great flight controller, exceptional aero, a nice camera and a really clean VTX...it should be a really great flying machine. If I could drop the weight, it'd be absolutely bonkers.