In development · schematic only. This is a planning document, not a verified build or operating instruction. Verify the exact flight-controller/ESC board revision, pinouts, signal direction, and every supply voltage against the manufacturer documentation and your hardware before soldering or connecting components. All performance figures are predictions until independently measured.
Reuse & attribution
© 2026 Jack Kidder. My original drone hand calculations, concept drawing, design/CAD materials, and build-reference text and tables published with this project are shared under Creative Commons Attribution–NonCommercial 4.0 International (CC BY-NC 4.0). The original supplied PDFs remain unchanged; this notice states the terms for my original content in them.
You may copy, share, and adapt these materials for noncommercial purposes with credit to Jack Kidder, a link to the source and license, and an indication of any changes. Suggested credit: “Hammerhead 5-inch speed quad — Jack Kidder, CC BY-NC 4.0; changes: [describe, or ‘none’].” Do not imply endorsement.
Commercial use requires separate permission, including selling products based on my design. Contact Jack on LinkedIn to buy directly or request commercial permission ↗. This is noncommercial sharing, not an open-source license.
The license applies only to my original drone materials, not third-party logos or trademarks, vendor documentation, linked resources, third-party content, or unrelated portfolio projects. Those remain subject to their owners’ terms. No patent or trademark rights are granted. Materials are provided as-is without warranty; reuse is not a statement of airworthiness or flight approval. See the full license terms.
What it takes to build and fly it
Prices are dated estimates/cart prices supplied with this build sheet (Oct 11, 2026), in USD before tax and shipping—not live-verified prices or proof of purchase. Ground gear (goggles, radio, charger) is reusable, so the aircraft-and-flight-pack subtotal is listed separately.
Showing filtered rows only; the aircraft and all-items totals below and every CSV export always include the full bill of materials.
| Qty | Part | Why | Source | Each | Line |
|---|
Not included: the motor/prop thrust stand (its own project), the Jetson phase-2 parts, and a 3D printer. A third CNHL 2-pack ($43.98) is optional for longer sessions.
Mass & CG budget
Stations in mm from the nose| Item | Mass, g | Station | Moment, g·mm |
|---|
CG = Σ(m·s) / Σm. Seven of ten entries are estimates until the printed parts are weighed, so treat the 184 mm CG as ±10 mm for now.
The CNHL pack is listed at 82 × 40 × 36 mm. Its cross-section diagonal plus wall and clearance needs about 58.8 mm of outer diameter along the bay (stations 79 to 161). Measure the real pack before printing the shell; the bay is sized to it, not the other way round.
One battery, three voltages
The 6S pack feeds the 4-in-1 ESC. The flight controller takes battery voltage through the 8-pin harness and makes 5 V and 12 V from it. Nothing except the ESC ever sees battery voltage.
Pad names and the harness pin order here come from published reviews of the Velox F7 SE stack, not from my own board. Check them against the manufacturer wiring diagram for your exact board revision. Some older boards are reported to use a 10 V BEC (labelled 5V/10V on the solder bridge) instead of 12 V; verify both that output and the air-unit input range from the current manufacturer documentation before connecting anything.
Connection schedule
7 runs| # | From → To | Conductor | Carries | Notes |
|---|
Power budget
From hand calcs| Load case | Value | Against limit |
|---|---|---|
| Hover, total electrical | 119 W | at 22.2 V nominal |
| Hover current, pack | 5.3 A | 4.1C on a 1.3 Ah pack |
| Hover current, per motor | 1.3 A | ESC rated 55 A continuous |
| Hover endurance, 80% usable | 11.7 min | Speed runs will be far shorter |
| Full-throttle current | — | Measure on stand |
| 5 V and 12 V BEC loads | — | 3 A each; check with a USB meter on the bench |
Full-throttle current is not predicted. The hand calcs only bound thrust there. The thrust stand measures it per motor and the number goes here.
First power-up
Props off- Check for shorts. Multimeter in continuity mode across the XT60 pigtail. It should not beep.
- Plug in through the smoke stopper. If its LED stays lit or the bulb glows hard, unplug and find the short.
- Measure the DJI plug before connecting the O4: about 12 V (or 10 V on older boards). Battery voltage here destroys it.
- Motors tab in Betaflight: confirm order and direction one motor at a time. Pusher props mount curved face toward the motor.
- Turn on bidirectional DShot and RPM filtering. The validation sheet relies on eRPM in the blackbox log.
- Calibrate the current sensor against a clamp meter at hover throttle before trusting any current log.
Eighteen numbers drive the whole model
The SolidWorks part is built off global variables. Change a and the motor pods, fin planes and clearance checks all move with it. Import the file below, then build sketches that reference these names instead of typed dimensions.
Global variables
Units: mm and degrees| Name | Value | Meaning |
|---|
Import into SolidWorks
Equations manager- Tools › Equations, then Import, and pick
SQ_Globals.txt. Tick all rows. - Square roots are written
sqr(). Everything after the apostrophe is a comment. - Plane offsets won't take an equals sign in the PropertyManager. Type a number, then double-click the dimension and enter
="s_max"in the Modify box. - Keep
gap_ppandgap_bodyat 6 mm or more. They are checks, not inputs; if one goes under, changeaor the prop.
Model structure
Feature order- Orientation. Fuselage runs along Y from the nose; +Z is up. The Front Plane holds the side profile.
- Station planes offset along the axis at
s_max,s_aft,fin_leands_prop. - Body. Profile sketch revolved about the fuselage axis, then shelled to
wallwith the tail left open. - Pod planes. Two planes through the fuselage axis and the diagonal motor positions at ±
a, ±a. Fins are sketched on these. - Fin and nacelle, one pod, extruded as a separate body (Merge off), then mirrored to four.
- Fin root flat runs to 34 mm from the leading edge. The two spar bores (13 and 29 mm) and the wire channel (21 mm) sit inside it, clear of the taper.
- Save Bodies to split shell, keel and pods into printable parts.
File contents
SQ_Globals.txt · CRLF line endingsEach prediction, and how it gets tested
Every number here is a prediction from the supplied hand calculations, not a measured result. The proposed pass bands are documented in advance; testing is still pending. Results should be recorded here after measurement, including failures.
| ID | Quantity | Predicted* | How it's measured | Pass band | When | Measured | Status |
|---|
The fin fore-aft stiffness (3,780 N/mm) is too high to measure with a dial indicator: a 2 kg load moves the tip about 0.005 mm, half the gauge's resolution. Only the frequency is tested for that mode. Blackbox logs must run at 2.7 kHz or faster to show a 1,330 Hz peak at all; otherwise the tap test is the only evidence.