My new FPV multirotor was in the air for only a minute when it plummeted to the ground. A bad solder connection on the VTX caused it. The loose wire made contact with something it shouldn't have. The flight controller, receiver and camera were damaged.

I have a lightweight micro FPV quadcopter. The frame is designed to carry a 19mm x 19mm FPV camera. I decided to replace the camera with the Caddx Ratel. The camera I’m replacing is a Foxeer Micro Arrow Pro. It is a good camera but I’m wanting to fly at night too. The Ratel is a few grams heavier but fit into the same space and mounted using the same screws. The 12m lens barrel and 2.1mm glass lens are the largest I’ve seen fit onto a micro camera so far. The horizontal FOV appears to be approximately 135 degrees. The 1200 TVL CMOS sensor has starlight sensitivity. On a clear night illuminated only by stars, the light level is about 0.0001 lux. The camera can capture images in that very low-light but low-light conditions result in image noise. Digital Noise Reduction (DNR) circuitry is an electronic filter that reduces noise. 3D NR improves on DNR by eliminating motion blur and graininess. Also, Wide Dynamic Range (WDR) adjusts the light intensity of different portions of the image which then shows objects that would ordinarily be muddied or obscured. Camera settings are displayed on screen and are changed with the OSD menu board which operates like a joystick. The menu board is temporarily attach by wire when needed. Installing a RunCam (UART) control adapter to change the settings through the BetaFlight OSD menu should work. The adapter is only 10mm x 14mm but there is no room for it. The frame is already chock full. So, the adapter will remain untested here. The OSD...Continue Reading

I found a dozen micro quadcopter drones in a closet. They appear to be between 3 and 6 years old. All ready to fly sets that include the quadcopter, transmitter, accessories and user manual. I decided to get LiPo batteries and have some fun before waste management got them. The oldest drones have imaginative designs and are festive night flyers. I was flabbergasted when I saw an identical quadcopter at Walmart this past weekend. It was selling for $80 on sale ($100 less 20%). I have completely under estimated the value of these things. The future is now.
The eclectic collection includes a quadcopter that uses WiFi and a smart phone instead of a RC transmitter. Two others combine a phone and a transmitter for assisted flight. Luckily the apps were still available to download. There are fast FPV drones which come with 5” monitors and sophisticated looking transmitters. A 220mm wheelbase camera drone can be flown in windy conditions and it has the best range of all. The smallest might be the most recognizable of the group because of the “Tiny Whoop” craze that followed. They're all fun.

I have improved my polystyrene foam cutter. The cost to build was about $10. Using household tools, a drill, soldering iron and glue gun it was complete in a couple of hours. The size accommodates polystyrene foam up to 1" thick. It is portable, powered by 2 alkaline D cell batteries. 3 inches of very thin steel wire is heated by resistance to just beyond the temperature polystyrene transitions. Polystyrene is safely cut in a ventilated area. The heat is minimized to avoid unhealthy fumes. As a result, cutting speed is more or less 9 inches per minute depending on the size and density of the PS. The cut is barely larger than the diameter of the resistance wire so detailed and accurately sized pieces and voids can be achieved. It also cuts thin molded PS (recycling symbol 6). The platform lifts off to change the batteries or resistance wire.
Resembling a pizza box, a 12" square frame made of 1.5" x .5" poplar with a .25" paper board top and bottom. The lumber was cut with a small hand saw. The top board is left unattached and small blocks are glued to the underside which keeps the top in position on the frame.
A light steel rod is bent at a right angle. One end of the rod is fitted into a hole in the frame and held with a set screw. The point of the screw tip is ground off. The arm is parallel to the surface at 2" above. The negative battery wire (22 AWG) is inconspicuously soldered to the rod using a heavy soldering iron. The resistance...Continue Reading

Brushless Micro Foam Quadcopter DIY
Since it's introduction last week, I've been bouncing it around the apartment. I began flying at ever increasing speeds and eventually made a mistake. The hard impact fractured the foam in several places but the propellers and motors were protected. One of the screws had broken loose from the camera's shell. The camera was undisturbed. More importantly, the quad didn’t mar anything that it hit. For now, cracks have been glued and the loose screw is repaired. Although my repair work is hardly noticeable, I don’t trust the integrity of glued foam. Anyway, the damaged part is a roughly cut prototype not the final version of it.

The Cherry Bomb measures 5" x 5" x 1.75” and weighs 30 grams. Basically, an impact resistant foam guard is bolted on. The protective rings are strengthened by the nearly Invisible clear plastic ducting. The assembly has proven to be durable. The rest of the unit can be completely disassembled if necessary. A simplified carbon fiber frame supports the motors. The F3 flight control / 4 x ESC board is isolated by vibration dampened mounting. There is more than enough room to tuck in a mini receiver. An OSD ready, 25 mW AIO FPV camera is mounted near the center of gravity under the protective shell. The guard and props are in the camera’s view. Unfortunately, that is unavoidable. The 46mm props and 0703 brushless motors are a powerful and efficient combination. A 250 mAh, 3.8V HV LiPo lasts for over 3 minutes. The battery adds 6g.

It’s been great fun flying around the neighborhood, the park and playground this summer. But thanks to the RC Groups field finder, I found a bigger flying field that is accessible by public transit and only 20 minutes away. There are 4 soccer fields placed end to end along the river. I’m guessing they are reserved by clubs. There are shaded areas, picnic tables, restrooms, a parking lot and cold bottled water vending machines too. The whole place was deserted when I was there. I only saw friendly grounds keepers. One seemed accustomed to RC modelers asking if it was okay to fly. “No dogs and don’t feed the geese”. That’s all he cared about. There is a fee to park but I got off a bus right outside the gates and it’s free to walk in.

It was a warm Summer evening. I put on bug repellant and went outside. This was the first full battery flight of a lightweight (75g gross) micro quad copter that I had recently built. The first couple of minutes was line of sight. Onboard LED indicators make it bright enough to track in the dark but didn't help with orientation. The fast motors and short props spin smoothly and quietly so I wasn't disturbing the peace. A “throttle punch” was respectable and after a few flips and funnels it was time to try the goggles. Since the flight control board has Betaflight OSD the peripheral screens are redundant and are turned off. Unfortunately, the camera isn’t configurable through the Betaflight OSD menu. A wired dongle is needed to change it’s settings. Using it was inconvenient enough that I’m already browsing for another camera. Taking off into the darkness, the clarity and brightness of the image was actually disappointing. This could be because I’m not adjusting the camera correctly. The FrSky X7 radio can take advantage of the 16 channels on the SBUS receiver. in other words, I need to remember or label the switches on the radio. There is no telemetry but the “full range” receiver shows RSSI in Betaflight OSD. I had previously set up 3 profiles but chose the BF 3.4.0 default PIDs with the rates changed to my liking. Flying around obstacles closer to the ground a propeller clipped a shrubbery. I was unaware that a blade broke off until afterward. Economy and distribution of power were challenges when building this. I’m happy that a small 2S LiPo lasted almost 7 minutes.

July 31st. Over the course of this month everything except for the frame, motors and camera had been changed out. The quadcopter has been put together, flown and taken apart a dozen times. This last change was quick and easy. Swapping out the VTX was done to reduce the load current. It worked and the image quality seemed improved too. But, there is a problem. I eventually figured out that the voltage from this new VTX to the camera is now dropping slightly below 5V. And, that isn't enough. Today, I’ll rework that and hopefully everything will be copacetic. If I shot a build video about this, it would be 4 hours long.

My last post was celebratory. I had finished building a micro FPV quadcopter. For various reasons, it had taken almost a month and I was glad it was finally done. Well, the celebration was early. I had overlooked the flight controller BEC specification. It could only handle half as much current as I thought. So, the FPV system I put together was causing a brown out. An additional BEC won’t fit so finding a lighter duty VTX became crucial. I eventually found one with a lower input current. I hope the specs are right. It will be here someday next week.

I've just finished the final flight testing for this is one. It's done!
Alfa-Genie 110mm Frame- This is a popular design theme these days. The CF frame kit has a 2.5mm base, 1.5mm top and pieces to mount a 19mm camera. Made of quality material that is nicely cut. Aluminum standoffs are 20mm.,
Halo F3 (Omnibus) Flight Controller and BS410 four in one 10A (BLHeli S) ESC Fly Tower Stack- Flight control and ESC boards are pre-assembled into a 20mm x 20mm stack. And, a LC filter is in line to the flight control board.
Crazepony BR1103 10000KV Motors & 2035 4 blade Propellers- These motors are running very smoothly (D Shot & Dynamic Filtering). The open motor bell is without screw holes so the propeller simply pushes on to the 1.5m shaft. The factory made bullnose props are well balanced.
FrSky XM+ 2.4G Diversity Receiver- A small "full range" 16 Ch. SBUS RX without telemetry. The firmware was flashed so RSSI can be seen in BetaFlight OSD.
Foxeer Micro Arrow Pro FPV Cam- A "better" camera with low light sensitivity is the whole purpose behind building this quadcopter. It has an on screen display and a detachable dongle to change settings.
Eachine VTX03 Video TX and Antenna- The frame requires a split cam and VTX. The unit is basic but has switchable power and a single character LED indicator. The light-duty antenna is attached with an IPEX snap on connector. The board gets very hot even at low power so it is mounted as far away from the rest of the electronics as possible.
7.4V 400mAh 30C- JST and balance charger connection. The flight times are about 6 minutes.
The weight is just 76g including the LiPo battery

Last night I was out flying after dark again. I’m still amazed at the view through the goggles. The twilight appearance of everything is erie. The sky has been clear which helps the visibility. Of course where the man made ambient light is stronger, there is less noise in the image. My little 1S drone is quiet, unobtrusive and dimly lit. I’ve spotted some wildlife around neighborhood. A bat catching bugs under a street lamp and a skunk rummaging in the dark recesses. A few blocks (300m) down the avenue, the light from the bars and restaurants looks very bright. I’d like to checkout the “wildlife" down there in a future (late night) adventure. Tonight’s forecast is cloudy and I’m interested to see the effect of that.

Tonight was the first time I've tried flying FPV outside at night. I flew a little brushless micro with a very inexpensive AIO VTX/Cam. The camera shows a grainy, washed out image in low light indoors. Outside it's grainy too but I could see pretty well. The resolution is poor. I'm in the camera's view but I look like a fuzzy blob in the picture. There is a lot of light pollution and the camera picks up on it. With the camera pointing towards Manhattan the sky is actually bright. Also, there is some color to the objects. This was about 45 minutes after sunset. To my naked eyes it was dark out there. Anyway, this is something I want to do more often.

2 cups of coffee. New batteries and a beautiful spring morning. New power for the goggles and transmitter too. I was flying fully charged.

I had been reading about building RC electronics like ESCs and receivers. While beyond my ability, I think it is interesting to read about what makes these things work. The fishpepper uSKY receiver was of particular interest to me because of the 10mm by 12mm size. While the tiny SBUS receiver started as a hack/project, assembled versions had become available here and there. I had come across a professionally assembled version from a factory in China. It looks identical to one now sold on Banggood. Anyway, the receiver operates at 5V. Compatible with the FrSky D8 SBUS protocol, binding to the Q X7 transmitter was simple. The assembly is neat, clean and a bind button has been added. The antenna wire is a generous 144mm long. So it was trimmed to an appropriate size for my quad. After insulating with heat shrink, the tiny receiver was tucked in between the standoffs of a 16mm stack. First tested inside, the uSKY worked reliably. Outside, the control distance is said to reach 200m. The 25 mW FPV signal only carries about 100m+ but the RSSI was still strong at that point.
Note: Betaflight 3.3.1 CLI syntax "set serialrx_inverted = ON” now replaces the old "set sbus_inversion = OFF”
To purchase a fully assembled receiver go to Banggood.com and search for 8CH-SUBS. Yes, they misspelled SBUS in the URL/description. Or, for more information about the open source check out https://fishpepper.de/projects/usky/

About a month ago I wrote about a micro size drone kit. The drone's frame isn’t so small (90mm) but the whole thing only weighs a few grams more than a “Tiny Whoop”. I don’t have a yard or a field nearby. But, I’ve got a bench outside my building and that is where I’ve been. I was astonished by the drones outstanding performance outdoors. The FPV signal carries for just over a block (100m). It’s great fun flying around the neighborhood. Over the past few weeks the configuration has been tweaked to the point of perfection. The combination F3 flight controller and 4 in 1 ESC is working flawlessly. The 0703 15000KV brushless motors are very quiet and after the flight they're still cold. I believe this is due to the DShot 600 ESC protocol and Dynamic Filtering in Betaflight. The motors and 3 blade props produce an abundant amount of thrust and the drone could afford to gain a little weight. So today, I’m building another Happymodel Trainer90 and I will continue to experiment.

This is very similar but not identical to another flight control board with the same description. The package includes a battery connector and buzzer. The lowest price was from Banggood (on sale $23.49).
The Fusion X3... is a compact, lightweight option for 1S brushless multi rotor DIY. This is not a corner mount “whoop” style board. Instead, this is rectangular and typically mounted on 4 standoffs attached to a frame part. It can handle a variety of 1S brushless motors and 3.7V and 3.8V LiPo batteries. Both the flight control and ESC are configurable and have fairly recent and stable versions of their firmware installed. There is 5V for a receiver (PPM, SBUS and IBUS), VTX, buzzer and LED. But, no 3.3V for a Spektrum receiver. Soldering the peripherals and motors takes forethought because there are connections on the top and bottom of the board. The 5A ESCs are big enough to handle the current that passes through 06xx and 07xx motors.
CPU: STM32F303CCT6 (72MHZ, 256K FLASH) MPU-6000 6DOF (SPI connection)
Power supply: 3.7V 1S
Voltage detection, alarm and 5V/1A step up regulator
Betaflight programmable OSD, buzzer and LED Strip
Receiver protocols: PPM, SBUS, IBUS, Spektrum DSM2 / DSMX, 1024/2048.
Betaflight Omni 3.2 firmware
BLHeliSuite programmable BLHeli_S 5A ESC (6A 3 sec. peak) Supports D-shot150, D-shot300, D-shot 600, Oneshot125, Multishot, PWM
Measures 28mm x 30mm and weighs 3.1g.
2.5M screw hole spacing: 16mm x 16mm

It is spring here in the northeastern U.S. Yesterday morning the sky was cloudy and the air was warm and still. I finally had the perfect conditions to fly a small ultra light quadcopter I had built. The power supply is relatively small so I wasted no time in testing the quadcopter's abilities. The performance was no less than spectacular. I felt elated. Returning to home and descending from a high altitude the quadcopter clipped a thin branch of new growth and spun out of control. The quadcopter was hung up in a leaf cluster helplessly looking down from the 40 foot tree top. Sadly, I sat there on the bench and watched as the battery quickly expired. I went inside and chalked it up as a loss. It would take a strong gale to free it from the entanglement. If it fell at sometime in the future, finding it would be unlikely. All that being said, a dry, and gusty wind kicks up overnight and blows it out of the tree. The next morning, I find it resting right side up, undamaged and in the same spot it took off from. I think that goes beyond being lucky.

The cost to build was less than $90 US. That includes the miscellaneous parts, spare props and 4 batteries. I’m happy with the results. It is nimble and resistant to damage in closed spaces. Out in the open, it is fast and wind conditions aren’t a problem.
Cutting a lightweight frame helped to offset the weight of crash guards. Using a diamond wheel and bits, it was easy to accurately cut through thin (2mm) carbon fiber leaving clean sharp edges on both sides. Bright yellow crash guards are attached to the simple X frame supporting a 20mm flight control and ESC stack. That consists of a Betaflight 3.1 Omnibus F3 6DOF Mini Flight Controller (Omni 3.3.1 firmware). And, a 6A 4X (DShot 600) ESC that controls the 1103 8000 KV brushless motors. They're spinning 4 blade 2035 propellers. The tiny 10mm x 12 mm S-BUS telemetry receiver (D8) weighs 0.8g. 100 meters is about the maximum reliable control distance. An AIO 25 mW VTX/600 TVL camera has video in and out for OSD. The VTX/cam is the smallest available measuring 13.9mm x12mm, 3.5g. The weight of the quadcopter is 66g including the battery. It is a 2S (7.4V) 350mAh LiPo. Flight times are about 6 minutes.

This is the 24 gram, 0703 KV15000 brushless motor version of the Trainer90 BNF kit. In the box of parts I found 2 sheets of paper showing wiring diagrams and the steps needed to bind the receiver to a transmitter. The model is assembled as shown in the pictures. It is important to note that the bottom end of the motor shafts must be supported while pushing on the props. I've already made a few modifications. The 3D printed camera mount was replaced. The receiver board is now part of the stack. And, snazzy new 3 blade props. The power supply is a "Whoop" style stick battery so the fun is interrupted every few minutes. The main board is a combo flight control and a 4 way ESC that eliminates wiring and compacts the setup. Solder connections are on the top and bottom of the board. And, inboard mounting holes let the board fit onto the 16mm x 16mm stack. It overhangs but the ESC solder pads conveniently line up with the frame arms. I’ve tightly wrapped the slender arms with vinyl tape which also protects the motor wiring. Otherwise, the electronics are typical for a micro these days. Using Betaflight OSD, adjusting the PIDS and rates while flying was faster and easier than going back and forth to a computer. I really like that feature. My configurations and transmitter setups have gotten more sophisticated lately but that is a subject for a different post.
Flying around the apartment, it is safe and durable even without propeller guards. But, I fly away from people, pets and delicate items. It has more power than needed. Outdoors, it is light, airy and beautifully acrobatic. Now the Trainer90 name makes sense to me.