Drone for a final-year project: parts list and design calculations

In most final-year projects the drone carries the real work: a sensor, a payload or some software. Buy an airframe that is known to fly, spend the semester on the project, and do the design sums properly, because the examiners will ask for them.

Pick a platform you won't have to debug

The platform we suggest for most projects is Holybro's X500 V2: a 500 mm carbon-fibre quadcopter that PX4 uses as a reference airframe and that ArduPilot flies just as well. The ARF version arrives with motors, speed controllers, propellers and the power board fitted. The development kit adds a Pixhawk 6C autopilot, an M10 GPS, a PM02 V3 power module and a SiK telemetry radio. Our kit comparison covers the S500 and X650 alternatives.

At our current prices the development kit costs less than the ARF kit plus the same avionics bought one by one. It also saves a week of matching connectors. Buy it unless your project is about the autopilot itself.

Budget kits built on copies of the old Pixhawk 2.4.8 cost much less, and many of them fly. The trouble starts when one misbehaves a week before your review. A copy has no manufacturer behind its sensors or its firmware support, and nobody can tell you whether the fault is yours or the board's. Holybro documents its boards' pinouts and wiring, and both PX4 and ArduPilot maintain firmware for them.

Choose PX4 or ArduPilot in the first week and stay with it. Both run on the Pixhawk 6C, but their parameters, logs and ground-station software differ, and a team that switches halfway through loses a month.

The weight budget

Every calculation starts from the all-up weight, so build the table first and keep it up to date. For the worked examples below we assume the X500 V2 weighs 1,450 g ready to fly with a 4S 5,000 mAh LiPo and no payload. That is a typical figure for this kit, but weigh yours: a kitchen scale is accurate enough, and a measured number reads better in a report than a quoted one.

Add your payload, its mount and anything else the project puts on board. A camera with a gimbal, a companion computer and its regulator easily add 300 g. For the examples we add 300 g, which brings the aircraft to 1,750 g.

Thrust-to-weight ratio

The motors must lift the aircraft with enough in hand to climb, fight wind and recover from a gust. For a camera or sensor platform the usual minimum is 2:1: total full-throttle thrust at least twice the all-up weight.

At 1,750 g that is 3,500 g, or 875 g per motor at full throttle. Read it from the manufacturer's thrust table for the kit's motor and propeller at your battery voltage. Ask us for the propulsion data for the exact kit we quote and we will send it. If the table comes out short, the payload is too heavy for this airframe, and the X650, with larger motors and 15-inch propellers, is the next step.

Hover power and flight time

Momentum theory gives the ideal power a rotor needs to hover:

P = √(T³ ÷ 2ρA)

• T is the thrust each rotor makes in hover, in newtons: all-up mass in kg × 9.81 ÷ 4.
• ρ is air density, 1.2 kg/m³ near sea level. Use a lower figure for a hot day or a high site.
• A is the disc area of one propeller. The X500 V2's 10-inch propellers sweep 0.0507 m².

Real hardware is less efficient. Divide by a figure of merit of about 0.5 for a propeller this size, and by about 0.78 for the motor and ESC. Add about 5 W for the autopilot, GPS and radios.

Example, 1,450 g, no payload. T = 1.45 × 9.81 ÷ 4 = 3.56 N. Ideal power per rotor = √(3.56³ ÷ (2 × 1.2 × 0.0507)) = 19.2 W. Electrical power = 19.2 ÷ 0.5 ÷ 0.78 = 49.3 W per motor, 197 W for four, 202 W with the electronics.

A 4S 5,000 mAh LiPo holds 14.8 V × 5 Ah = 74 Wh. Using 80% of it leaves 59 Wh, so the hover time is 59 ÷ 202 × 60 = about 18 minutes. Holybro quotes about 18 minutes of hover for this kit on a 5,000 mAh pack with no payload, which is a useful sign that the assumptions are sensible. Put that comparison in your report.

The same sum with a payload, and with a second pack:

The last row is the lesson worth writing up. Doubling the battery doubles the energy but adds 500 g, and hover power rises with weight to the power 1.5. The second pack buys five minutes, not thirteen, and takes much of the thrust margin with it.

Current, the speed controllers and the battery

Divide hover power by pack voltage to get the current: 267 W ÷ 14.8 V = 18 A in total, about 4.5 A per motor. That is the figure to use for heat and wire sizing in hover.

The full-throttle current per motor comes from the thrust table, and it must stay below the ESC's continuous rating. The X500 V2's speed controllers are rated at 20 A each.

For the battery, divide the maximum total current by the capacity to get the C-rating it must sustain. Four motors at 15 A each draw 60 A, which is 12C from a 5 Ah pack. Holybro recommends a 4S LiPo of 3,000 to 5,000 mAh rated 20C or better, with an XT60 connector, so a 20C pack has margin.

The PM02 V3 in the kit measures voltage and current and powers the autopilot. Holybro rates it at 60 A continuous, well above this aircraft's hover draw.

Check the sums against a real flight

Your estimate uses two assumed efficiencies, and a real flight replaces them. Once the aircraft flies:

1. Hover for three minutes in a position-holding mode.
2. From the log, take the average voltage and current, and multiply them for the hover power.
3. Work the figure of merit back out of the equation and compare it with the 0.5 you assumed.
4. Redo the flight-time estimate with the measured power.

A table of estimated against measured figures, with a sentence on why they differ, is worth more marks than either on its own.

Look at vibration too. ArduPilot's guidance is that levels below 30 m/s² are normally fine and that above 60 m/s² position and altitude hold suffer. PX4 logs the same data and plots it in its log review tools. If the payload mount rattles, the log will show it before the flight does.

What the design chapter needs

• The weight budget, measured, with the payload listed separately.
• The thrust-to-weight ratio, with the thrust table you took it from.
• Hover power and flight time, estimated and then measured.
• Current at hover and at full throttle, checked against the ESC, battery and power-module ratings.
• The centre of gravity, and how you set it. Put the payload under the centre of the frame and slide the battery to balance.
• Failsafe settings: what the aircraft does on losing the RC link, the telemetry link or battery.
• Vibration levels from a real log.

Before you fly in India

Ready to fly, this aircraft weighs between 250 g and 2 kg, which makes it a micro drone under the Drone Rules, 2021. Rule 42 exempts research and testing flights by educational institutions recognised by the central government from the type certificate, unique identification number and remote pilot certificate, when they fly within their premises or in a green zone. Check with your department how it applies this, and look at the Digital Sky airspace map before flying anywhere else.

Confirm which telemetry band you may use before you order the kit, because the 433 MHz and 915 MHz versions are different part numbers. Our telemetry radio guide explains the choice. If the project needs onboard computing, see the companion computer guide. For a smaller, faster aircraft with the same electronics, see the 7-inch build.

Sources.

• Airframe, kit contents and recommended battery for the X500 V2 from Holybro's X500 V2 kit page and PX4 development kit page (accessed 2026-09-23). The hover time of about 18 minutes on a 5,000 mAh pack with no payload is Holybro's.
• Current rating of the PM02 V3 from Holybro's product page (accessed 2026-09-23)
• Vibration limits from ArduPilot: measuring vibration (accessed 2026-09-23)
• The R&D exemption and drone categories from the Drone Rules, 2021 backgrounder published by PIB.
• Hover power from momentum theory, as set out in J. G. Leishman, Principles of Helicopter Aerodynamics. The all-up mass, figure of merit and motor efficiency in the examples are our assumptions, not measurements.

Published 23 September 2026. Last revised 25 September 2026. Corrections to sales@vebixautomation.com.

Ordering for a department?

Send us the project, the payload and the flight time you need. We will confirm the kit contents in writing and send a formal quotation with part numbers and HSN codes that your department can raise a purchase order against. Ask for a quote.