Team 7 Conservation · Capstone
Removing illegal drones without breaking everything under them
A low cost interceptor that catches a drone in a net instead of shooting it down.
02 / Problem statement
Rogue drones are cheap, easy, and everywhere
A drone costs a few hundred dollars. The countermeasure used to stop it can cost more than the drone, which makes flying one a very low risk activity for whoever is doing it.
The scale
| Signal | Figure | Source |
|---|---|---|
| Drone related violations recorded in 2023 | 1,067,112 | team research doc |
| Unauthorized sightings reported to the FAA per month in 2020 | over 100 | team research doc |
| Flights disrupted at Gatwick in 2018 by one drone | 837 | paper 3, Yu et al., 2022 |
| Passengers affected across 24 hours at Gatwick | over 130,000 | paper 3, Yu et al., 2022 |
| Military drone market in 2023 | 14.14 billion dollars | team research doc |
| Projected market in 2032 | 47.16 billion dollars | team research doc |
| Fortem DroneHunter 5.0, per unit | about 100,000 dollars | competitor analysis |
Why today's answers fail
The tools that exist were designed for war, where stopping the drone is the only priority and debris is an accepted cost. In a civilian setting that cost lands on people, property, and the evidence needed to identify whoever was flying.
Three problems with the obvious answers
Shooting it down
Falling debris lands on whatever is under the drone, and the airframe is destroyed so the operator can never be identified.
Jamming the signal
Interferes with communications well beyond the target and the drone is lost rather than recovered, so there is no evidence trail.
Buying a military interceptor
The Fortem DroneHunter 5.0 runs about 100,000 dollars per unit and weighs about 18 kg. That is a military tool, not something a park or a campus can field.
Who carries the cost
Critical sites are the obvious target. Airports, prisons, power plants, and communication sites are attractive because a drone is cheap and deniable, and a single unknown aircraft can ground an entire day of flights. Protected land sits in the same category with even fewer options, because the people responsible for it are usually unarmed, thinly spread, and legally boxed in.
Everyone else pays in smaller ways. Malicious drones blend in with legitimate ones, so every harmless flight makes enforcement harder. Falling wreckage from countermeasures becomes its own hazard. And when the law goes unenforced, the violations grow.
We need to quietly disable a drone without generating debris.
03 / Research and brainstorming
The physics is already proven. The price is not.
Three published papers establish that a net can be launched from a drone and that it catches a target. None of them produced something a civilian operator could actually buy, build, or legally use.
What the literature already proved
P1, ground launched net
Xu and Wu, 2025, in Drones. Optimized launch angle, launch speed, and block mass in simulation, trading net coverage against hang time. The lesson for us is that the net is only wide enough for a moment, so timing decides the capture.
P2, drone carried net
Han and others, 2026. A Kevlar net, 3 by 3 m open, fired by six tungsten weights at 75 m per second. Simulation matched field tests above 80 percent across deployment, collision, and entanglement.
P3, complete launcher
Yu, Judasz, Zheng and Botta, 2022, AIAA SciTech. A working pneumatic launcher for a hunter drone, built for under 50 dollars in materials at 0.80 kg. This is the direct ancestor of our design.
What nobody has done
There is no low cost, open, civilian legal interceptor that combines detection, tracking, and non destructive capture in one package. The market leader costs about 100,000 dollars and is closed. The research literature is small compared to the size of the problem. That gap is where a small team can contribute, by building the affordable version and publishing what it actually does.
How we brainstormed
We started from every interception method we could find, impact, electromagnetic interference, lasers, kinetic systems, and net capture, and scored each one against three questions. Does it create debris. Does it interfere with anything else. Does it leave the evidence intact. Net capture was the only method that answered all three the way a civilian setting needs.
Why net capture wins on our criteria
| Method | Debris | Interference | Evidence kept | Cost |
|---|---|---|---|---|
| Shoot it down | Heavy | None | Destroyed | High per engagement |
| Jamming | None | Severe | Lost | Medium |
| Lasers | Heavy | None | Destroyed | Very high |
| Net capture | None | None | Intact | Low |
04 / Design and planning
Two subsystems, one aircraft
The quad flies. The launcher does the work. Every gram is budgeted because the net catcher alone is nearly a third of the aircraft.
Mass budget
| Subsystem | Target mass | Allowed maximum |
|---|---|---|
| Frame, landing gear, mounts | 450 g | 600 g |
| Motors and propellers | 360 g | 480 g |
| ESC, flight controller, GPS, wiring, power | 220 g | 320 g |
| Battery | 750 g | 950 g |
| Net catcher and actuator hardware | 900 g | 1,150 g |
| Camera, sensor and telemetry hardware | 120 g | 200 g |
| Fasteners, straps, isolation, contingency | 200 g | 220 g |
| Total takeoff weight | 3,000 g | 3,920 g |
Drive targets
| Parameter | Value | Why |
|---|---|---|
| Mission weight | 3.0 kg | normal flying weight with the launcher loaded |
| Design maximum | 3.6 kg | headroom if the net catcher runs heavy |
| Hard limit | 3.92 kg | above this the aircraft stops being controllable |
| Propellers | 9 to 10 inch | sized from the thrust target, 11 or 12 if the airframe grows |
| Battery | 6S | higher voltage keeps current and heat down |
| Thrust to weight | 2.3 to 1 minimum, 2.5 to 1 target | gives the agility to line up a moving target |
The launcher chain
Air tank, then regulator, then solenoid valve, then the printed barrel, then the net. The tank is a 13 ci aluminum bottle rated to 3000 PSI and refilled from a paintball station. An inline regulator drops the working pressure to a fraction of that. A 12 V solenoid valve fires the shot when the flight controller tells it to. The barrel is printed in house with four tubes angled outward, and it doubles as the net storage compartment. The net is roughly 10 by 10 inches of nylon with steel weights on the corner tethers.
The valve choice mattered more than it looks. We needed something that holds pressure, opens electrically, and does not choke the airflow on the way out. The affordable answer was an irrigation style valve with its stock solenoid swapped for a larger one, which gives a faster pressure drop and a stronger launch.
The plan we submitted
- Phase 1Problem analysis and research, completed this quarter
- Phase 2Solution design and planning, underway
- Phase 3Development and testing, launcher build and bench tests
- Phase 4Implementation and evaluation, flight tests against a target drone
- Phase 5Final presentation and documentation
The launcher chain
Air tank, regulator, solenoid, barrel, net. The flight controller closes a 12 V circuit and the solenoid drops the valve diaphragm. Everything upstream only has to hold pressure and stay out of the way of the airflow.
Where the mass goes
Every subsystem has headroom except the one doing the work. The net catcher is budgeted at 900 g of a 3.0 kg aircraft, which is why the design maximum sits at 3.6 kg.
05 / Building process
Every part priced before anything is bought
Long lead items were the reason this page exists early. Specialized parts can take weeks to arrive, so sourcing came before assembly.
Launcher hardware
| Part | Specification | Qty | Price | Vendor |
|---|---|---|---|---|
| Nylon netting | 3 by 3 ft knotted nylon, 1.75 inch mesh | 1 | 35.00 | Nets of America |
| Air tank | 13 ci aluminum, 3000 PSI | 1 | 49.95 | East Coast Paintball |
| Inline regulator | adjustable, paintball thread | 1 | 52.00 | Amazon |
| Tank adapter | regulator to tank fitting | 1 | 8.99 | Amazon |
| Tubing | high pressure hose | 1 | 11.99 | Amazon |
| Solenoid valve | 1/4 NPT, 12 V DC, normally closed | 1 | 10.69 | US Solid |
| Subtotal | launcher hardware | 168.62 |
Free or in house
Net line comes from the robotics shop, the steel slugs that weight the corner tethers are cut from scrap, 3D printing filament is covered by the shop, and two air canisters are already available at school. That keeps the cash outlay for the launcher at about 170 dollars, which is less than one percent of the cost of the commercial alternative.
Assembly order
- Step 1Pressure test the tank and regulator at low pressure only, then step up
- Step 2Print the four tube barrel and check that the net packs into it cleanly
- Step 3Wire the solenoid and confirm the trigger fires from a bench switch
- Step 4Attach the net to the four weights and load the barrel
- Step 5Film the first dry fire and record opened area and range
Slot reserved
Build photos
Bench test stills and a short clip go here as soon as the launcher fires. Until then this panel marks the slot so the page keeps its shape.
06 / Iterations and refinements
What we changed and why
Most of the work this quarter was choosing between options and throwing the worse one away. These are the decisions that moved the design.
Decisions we revised
A paintball tank instead of PVC
The reference launcher uses PVC pipe as a pressure vessel. We moved to a rated aluminum tank because a shop built pressure vessel of unknown rating is not something a school team should pressurize.
An irrigation valve with a bigger solenoid
The stock solenoid was too small to drop the diaphragm quickly. Swapping it for a larger one was cheaper and simpler than designing a valve.
Four tubes, not one
A single barrel tends to launch a net folded rather than open. Four angled tubes pull the corners apart as it leaves, which is the difference between a net and a bundle.
Nylon over Kevlar
Kevlar outperforms nylon on strength, and it also costs far more than a first prototype justifies. Nylon baseball netting is the cheap test bed, uprated later if the concept holds.
A 3.0 kg aircraft, not 6 kg
Our early framing used a heavier craft. Working the mass budget from the payload up settled it at 3.0 kg with a 3.6 kg design maximum, which changes the props and the battery selection.
The use case narrowed to protected land
A general counter drone product has to satisfy everybody. Narrowing to conservation and protected areas gave us a real user with a real gap, and it keeps the design honest about collateral risk.
What we would try next
Two refinements are queued behind the bench test. Net shape is one, since a rectangular mesh opens differently than a diamond one and the literature suggests shape matters as much as size. The other is launch pressure, because the sweet spot between a net that opens and a net that tears is something only testing will find.
07 / Final solution
A capture, not a kill
The target is a 3.0 kg interceptor that flies to a rogue drone, fires a net across its path, and brings it down without destroying it or anything under it.
How an intercept runs, in four moves
Detect, close, launch, recover. The net is the only part that touches the target, and it is the only part that has to be built from scratch, which is why the whole test plan points at it.
Where the net has to open
A net opens wide and then contracts, so the capture only works inside a narrow window of distance and time. This is the problem the trigger has to solve, and the reason the bench test measures distance rather than just success or failure.
Why it fits protected land
A ranger cannot shoot a drone out of the sky over a wildlife corridor, and jamming one would take out the radios the team is using. A net does neither. It does not start a fire, it does not scatter wreckage across habitat, and it hands back an aircraft with a serial number and a flight log on it, which is what turns an incident into a case.
Cost is what makes it deployable. The commercial interceptor is about 100,000 dollars a unit. Our launcher hardware is about 170 dollars and the aircraft is built from standard parts, which puts the whole system in a range a park budget could actually absorb.
Target specification
| Parameter | Target | Status |
|---|---|---|
| Takeoff weight | 3.0 kg | budgeted |
| Design maximum | 3.6 kg | budgeted |
| Propellers | 9 to 10 inch | selected |
| Battery | 6S | selected |
| Thrust to weight | 2.5 to 1 | derived from mass budget |
| Launcher hardware cost | 168.62 dollars | quoted and sourced |
| Net open size | about 10 by 10 inches | first prototype |
| Bench test | opened area, range, hang time | next |
Recovery is still open
How the target comes down is the one part of the intercept we have not settled, and we are not going to pretend otherwise. Two options are on the bench this quarter. Option A is a parachute packed with the net, which opens on capture and lowers the aircraft on its own. Option B is a tether, a line running back to our own aircraft, so we carry the captured drone home instead of releasing it. Both are being tested, and we pick one on the evidence rather than on which is easier to draw.
One constraint applies to whichever we choose, and it is not negotiable. The target has to come down under control, in a place we can name in advance. A net that catches a drone and then lets it fall is not a solution, it is a second accident, and the whole reason this project exists is the people and the animals underneath.
Two options on the bench
Option A, parachute
A chute packed with the net. Light, simple, and it does not change the aircraft at all. The open question is drift, because a canopy in wind decides where the target lands rather than us.
Option B, tether
A line from the net back to our aircraft, so the captured drone is carried rather than dropped. Full control of the landing point, paid for in weight and drag on the interceptor.
The test both have to pass
Controlled descent, a known landing area, and no free fall over anything that matters. We would rather fly a heavier aircraft than drop a drone on a crowd.
Recovery, two candidates and one rule
Neither method is chosen yet. The parachute removes weight from the interceptor and gives up control of the landing point, the tether keeps control and costs payload. Whichever wins has to prove a controlled descent into a known area, because dropping the target would defeat the point of catching it.
What it does not do yet
We have not flown it. Nothing on this page has been in the air, and the capture has not been demonstrated against a moving target. The next quarter is about turning a budget and a parts list into a launcher that fires and an aircraft that carries it.
08 / Conclusion and impact
Cheap enough to actually put on a truck
If this works, the difference is not a better interceptor. It is an interceptor that a park, a campus, or a small department can own.
What changes if we succeed
Every countermeasure in service today is either destructive or expensive, and most are both. A non destructive capture at a fraction of the price changes who can respond. It also changes what a response produces, because a recovered aircraft is evidence and a destroyed one is litter.
The design is deliberately open and made of parts anyone can buy. If the numbers hold, the same launcher design scales up for larger targets and down for indoor use, and the test data we publish gives the next team a starting point instead of a blank page.
Limits we are honest about
One net, one target
A single interceptor catches a single drone. Higher traffic needs more interceptors, not a better net.
Range is set by the aircraft
The net cannot reach further than the quad can fly, so detection and interception have to be close to the protected site.
Authority is still a barrier
Even a safe system needs policy that lets a non federal operator use it. That is part of why ours is built to catch rather than destroy.
Next quarter
Buy and assemble the launcher, pressure test it in stages, bench test the net and record what it actually does, then mount it on the 3.0 kg aircraft and tune the trigger. The goal for the second quarter is one complete capture, on camera, at a known range.
09 / About the team
Team 7 Conservation
Three students in the Innovation and Design Capstone, working on one problem for the school year.
Lewis He
Project Manager
Software, data analysis, physics
Runs the schedule, owns the software side, and keeps the engineering numbers honest.
Alex Shi
Research Lead and Implementation Strategist
Research, mechanical engineering, software
Built the literature base, sorts what is actually feasible, and plans the tests.
Shane Reidy
Prototyping Engineer
Rapid prototyping, electronics, fabrication
Turns the drawings into hardware and owns the launcher build.
How we work
The Gantt chart splits the year into five phases and rotates responsibilities so nobody owns only one kind of work. Each phase has a named owner, every deliverable has a reviewer, and the whole plan is public on this site rather than living in someone's head.
Advisor is Mr. Anderson. The project runs through the Innovation and Design Capstone at Los Altos High School, 2026 to 2027.
Contact
Questions about the project, our test data, or the design are welcome. Reach the team through the Capstone course at Los Altos High School.