AirBlade Transformer Mini 4 Inch Micro Long Range FPV
#microlongrange is here!
Most of what you see on the FPV drone market are drones that are powerful and fast, but very little attention is paid to the type of drones that can fly longer and further.
So the idea naturally came to us, what if we were to design a micro long range 4 inch FPV drone that are similar to a DJI Mavic Mini? Here are key features we want to incorporate in this design:
- Sub 250g. Amid the uncertain time that we are in, it is safe to say that small and light drones are still a favourable choice to many pilots, novice and seasoned alike.
- Long flight time. The DJI Mavic Mini is boasting 30 minutes flight time with Li-Ion battery. We will be aiming for 20 minutes flight time and, if possible, more.
- Capable of capturing HD footage
- Capable of doing mid range to long range flights
Given the features above, here is our thought process:
- The DJI Mavic Mini carries a 2400mAh 2S Li Ion weighing roughly 100g, which gives it 150g for the dry weight of the drone. Since we can definitely build a dry drone for about 120-130g, that leaves us 120-130g for battery. So we will be going for something like a 3500mah 2S Li Ion or 4200mah 2S Li Ion.
- Let's assume that we have 130g of dry weight to play with, that limits the motor choices to anything t-mount and smaller than 1407. That leaves us with 1306, 1404, 1303, 1204 motors. Generally, pancake style motors are more efficient so we decided to look at 1404 and smaller.
- Now because we only fly on 2S Li-Ion battery, which has an operating range of 5.5V-8.4V, we need to maximize thrust by changing the prop diameter as well as motor kV. The biggest motor in this case is 1404 which can safely handle 4 inch propeller. We will be testing the Superman 1404 4850kV but we think this setup can run up to 6500-7000kV on 2S without a huge penalty in current draw.
- The next step was to get some number to confirm our theory, so we contacted Ethan Bayer at Micro Motor Test Lab and have him tested our Superman 1404 4850kV with HQProp T-mount 4 Inch T4x2.5 and the numbers look quite promising. The 4850kV motor pulls about 3.5A to produce 120g of thrust on a static stand. We expect the current draw to be better in-flight.
- So now that we have our prop and motor combo picked out, the rest of the electronics can be easily solved. We want it to be as light as possible so a AIO board is the best candidate. Between a AIO Whoop 26x26 FC and HGLRC Zeus 20x20 FC, we opted to go with AIO Whoop 26x26 FC. However the frame is designed to do both. Given the current draw number we saw earlier, a 12A AIO FC board will do, but if you want to be safe, go with 20A version.
- To capture HD footage, we want to make it versatile, so the frame design will accommodate both RunCam Hybrid/Split as well as Caddx Vista for pilots using the DJI HD system.
- So our final electronics selection will be
- AirBlade Superman 1404 Motors
- BetaFPV 12A Toothpick AIO Flight Controller (if you want to use GPS, you will need a different AIO board with enough UART ports such as the BetaFPV 20A Toothpick AIO Flight Controller)
- TBS Crossfire Nano RX with Immortal T Antenna
- TBS Unify Pro V3
- RunCam Hybrid HD FPV Camera or Caddx Vista Kit
So at this point, what we are building is a light 4 inch Micro Long Range FPV drone capable of HD. Leveraging on our existing line of frames, we will be using the Transformer as our base. The benefits of using a Transformer frame is that
- Double stack for better electronic layout
- Long body for battery space
- Dead-cat design for prop-free footage
Here is the first stab at the design
We sent out a couple frames to our test pilots and immediately started working on some minor revisions.
UPDATE 1 (April 10 2020)
The frame is being cut as we speak, we are hoping to get our first shipment around the third week of April. Also, we designed a holder for Immortal T antenna and GPS. The Immortal T antenna holder will be bolted on the top of the top plate with one of the standoff screws, while the GPS holder will be slide over the back standoffs.
UPDATE 2 (Aug 13 2020):
We made some minor changes to the camera cage to include mounting holes for Insta360 GO or Naked GoPro HD cam. We also added the 12mm mounting holes for motors in future production run.