The build and procedure notes are
The World Is The Supply Chain Even For Specialty Parts - Cusped Airfoil, Rebranded ESC
Cusped airfoil 10.5% thickness (joukowsky10.5 for short) rotor blades are interchangeable with conventional parts: The production build's cusped airfoil on the rotor blades is known to extend the efficient angle of attack range for thin blades, discussed in https://estebanhufstedler.com/2020/09/24/joukowski-airfoil-l-d/ and https://estebanhufstedler.com/2020/07/14/improving-the-naca-00xx-airfoil/. The Fusion 180mm blade is modified from the NACA0010.5 thin airfoil with a cusped trailing edge. The result is that its fuel economy is nearly identical to that of the NACA0012 medium-thickness airfoil under the same operating parameters (blade speed and alpha). The reduced drag for the high angle of attack also keeps the stall angle of attack outside the operating angle of 10 degrees, similar to NACA0012. Video of the endurance test (6 degrees collective pitch) and an extraneous test (10.5 degrees) below. The NACA0012 blades operate with optimal efficiency at 5 degrees of alpha in static tests, and due to the quirk of vertical rotor fluid dynamics, the optimal angle of attack for cruising is 1 degree higher than that of the static test. Since the cusped blades perform nearly identically to NACA0012 blades, the production build's endurance cruising test was done with 5+1=6 degrees of collective pitch.
Extraneous (10.5 degrees alpha) test with high headwind here.
The part listing is in the following table.
Combo products are entries across different spreadsheets of this project, but split combo pricing to individual entries. Shipping discounts for multiple items from a vendor have been applied. No volume discounts.
The Horizon (Blade brand) components are priced the same on eBay and Amazon both with free shipping, as shown in the eBay and Amazon checkouts.
The entire craft is built without a machine shop and can be repaired by professionals in a car. Only light hand tools and light electric tools powered by car batteries are needed. This creates jobs.
Weight breakdown is https://nocomputerbutphone.blogspot.com/2018/08/iot-drone-weight-breakdown.html .
The World Is The Prototyping Studio - Congruent Parts, New Comers
The Align 300x has the same diameter and nominal length as the Blade Fusion 180. Align uses metric length 38 mm; Blade uses imperial length 1.5 inches. However, all suppliers use metric bolt threads and rod diameters. This is the base from which many brands/manufacturers make interchangeable parts.
1) Betaflight Software version 4.2.5 with the Zeus does not allow a reboot sequence to enter boot loader mode.
2) Not allowing entering boot loader mode means the hardware boot loader button needs to be used.
3) Using the hardware boot loader button means UART1 connecting to RF control receiver blocks USB flashing betaflight software version 4.5.2 unless UART1 is desoldered.
4) LED signal wire reassigned as S5 signal wire cannot flash FVT ESC, which needs resoldering to S4 pin to do the flashing.
Skystar Mini F4 solves all 5 hardware bugs.
The only difference between Skystars F7 and HGLRC F7 is the pinout assignments and physical chip orientations, and Skystars' accessory VTX wire pin voltage is reversed in one purchase out of three, as pictured below the correct voltage orientation. The reversed voltage destroyed two of my VTXs before I figured out the reversal.
$ diff dump_all_converged_IoT_HGLRCF722_6pin.txt dump_all_converged_
IoT_SKYSTARS_MINIF7.txt
6,7c6,7
< # Betaflight / STM32F7X2 (S7X2) 4.5.2 Mar 28 2025 / 21:47:17 (024f8e13d) MSP API: 1.46
< # config rev: 48588b7
---
> # Betaflight / STM32F7X2 (S7X2) 4.5.2 Aug 6 2025 / 03:55:33 (024f8e13d) MSP API: 1.46
> # config rev: 21f88d7
240,241c223,224
< serial 0 2 115200 115200 0 115200
< serial 1 64 115200 57600 0 115200
---
> serial 0 64 115200 57600 0 115200
> serial 1 0 115200 57600 0 115200
243,244c226,228The SParkhobby 1303.5 2500kv motor is a drop-in replacement for the HGLRC 1303.5, as pictured above for weight comparison. Skystars F7 Mini and SParkhobby 1303.5 motor have been verified on August 27, 2025, in the ground station setup note's weather prediction section with a successful beach dive. The Flycolor Fairy20A needs two different governor P=0.25 and Startup=0.75 parameters from traditional multi-rotor ESC brands, FVT, and DYS. Test video is here on the right. With the two new governor parameters different from the production build's, there is no difference in punch-up power and endurance (see the extreme robotics build tail_pid section for production build battery test with the two parameters' deviation), nor differences in punch-out tail bump characteristics from the production build. The post-stabilized video is below.
Every single part, bolt, and nut has more than one interchangeable source from independent business entities. See discussions in the following pages,
A summary of the dimensions of all component options is in the following table. And the reference component diagram is beneath the table.
Blade 180CFX Linear Bushing non-DFC Needs More Research Before Mass Use
The Blade 180cfx rotor (1.69g hub + 2.24g grips +0.82g thrust +0.90g radial + 0.53g blades bolt + 0.25g dfc = 6.43g) weighs 0.45 grams less than production build (1.4g hub + 3.7g grips + 0.1g washers + 0.9g dfc +0.8g dfc bolt = 6.9g). The grips are nearly identical (4.48 grams) in weight to production build when blade and DFC boltings are included; the DFC links are 0.4 grams lighter when the radial swasharms are included as part of DFC links.
The dyed rods don't use the common metric bolting pitches. In the last picture above, the M2 bolt's common thread pitch is 0.4 mm. The dyed rod is thinner than the M2 bolt, either M1.6 or M1.4, with a common thread pitch of 0.35 mm and 0.3 mm, respectively. However, as the picture showed, the thread teeth perfectly align under light. This is likely so, to reduce the turning needed when adjusting the DFC or servo link. The production servo link's die thread pitch is measured at 0.35 mm.
This Blade 180cfx rotor has thrust bearings and has zero slop of the feathering shaft, as is, without flanged washers. When you look up the rotor dimensions chart, you see a 0.25 mm hub-grip gap, but this gap is filled by the rubber grommet fully. As shown in the dimension chart, the 180cfx's DFC link is (11.3+11.2)-(10.8+10.7)=1 mm longer than the production build's Infusion180 DFC link. So, the servo link needs tightening 1/0.35=3 full turns, or 6 half turns, or equivalently increasing 90us PWM.
The installation is more complex with thrust bearings than the production build without thrust bearings. Production can not use the thrust bearings unless an assembly line is trained for it.
The Flycolor Fairy 20A main rotor ESC's Startup setting can not be the same as the production build's FVT ESC. The 1.25 setting produces oscillation and cannot spool up, and the lower the Startup setting, the less oscillation. The 0.5 setting is insufficient when the battery is half discharged, as shown in the following test. The first punch-up is good. All other punch-ups after the first one have fatigue and momentary failures indicated by the non-increasing altimeter reading.
However, the false solution 1.0 Startup for the main motor can still produce oscillation, failed spool-up, and the false workaround of paused spool-up at -93 from 97.8, as pictured, with false workaround video here on the right, with the very same battery and the same starting voltage as the previous test with 0.5 Startup. It shows consecutive 4 punch-ups over the course of the mission of nearly 10 minutes.
The last test video had a tremor from 8:36 (12 seconds after the start of diving) to 8:41, if you pay attention to the tree top line while not looking directly at it for the vibration with the full-size video. It is well known that human peripheral vision is more sensitive to light intensity and flickering.
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When I reduced the linear bushing gap with 2 layers of clear tape on the DFC links (4 layers filling for each link), the tremor persisted, raw video on the left, post-stabilized on the right. The tremor is between 0:12 and 0:17 during punch-out in the video, and the tremor frequency is faster than what PID vibration can produce.
The tremor can be diagnosed on tethered hovering with non-zero collective pitch when I feel like my hand is holding a sonic cavitation machine when it is operating.
The punch-out tremor was not caused by rotor imbalance as the 5th break-in mission's dive gyro graph shows here.
The punch-out tremor persisted into the 5th and 7th break-in missions, as videos and gyro graphs below.
Video verification is here, raw video on the left, post-stabilized on the right, taken immediately before taking the above 2 pictures. There is no tremor between 0:12 and 0:17 during punch-out. There was no modification to the craft other than the 90us PWM points compensating for the DFC link length difference, as evident by the consecutive video sequence number S0001, S0002 (landing), S0003 (takeoff), to S0004. Correct RPMs for temperature 74F for S0001 and 64F for S0004.
The minimal punch-out tremor (undetectable in video form) of the 3rd break-in mission of the production build verification videos is here, which has half of the noise amplitude as with the 180cfx DFC's 5th break-in mission and 70% of the noise amplitude as with the 180cfx DFC's 7th break-in mission. The amplitude is about the same as the diving tremor amplitutde of the 5th break-in mission with the 180cfx DFC.
The same Flycolor Fairy 20A ESC works with the production DFC rotor with the same spool-up false solution and false workaround. Pictured here is the same hub that produced the tremor video, but with the production DFC link and grips.
