Your first build

Build in this order

1. 01

   Decide the class before anything else

   The first decision is not a frame, a motor or a battery. It is the prop class: 3 inch, 5 inch, or 7 inch and above. Frame footprint, motor stator, current draw and battery weight are all downstream of this one choice, so make it first, and make it for a reason: where you fly, how far, and how much crash risk you can take while you are still learning to solder.

   A 3 inch quad fits a car park or a modest garden and is cheap enough to crash without flinching. 5 inch is the default freestyle and racing size, the one most parts exist for. 7 inch and above trades agility for range and flight time, and it costs and weighs enough that a wrong choice here is expensive twice: once in the parts you bought, once in the ones you buy to replace them.

   The former Mode 2 FPV Ghost 2 frame shows what moving up a class costs inside one design family: the same basic frame weighed 60 g in its 4 inch version and 75 g in its 7 inch version, without changing anything about the construction, only what it had to carry.

   Ghost 2 weight by prop class

   Class	Weight
   4 inch	60 g
   5 inch	65 g
   6 inch	70 g
   7 inch	75 g

2. 02

   Pick the frame, then read its FC mount

   Once the class is fixed, the frame follows, and the frame decides something most first builds get wrong: the mounting pattern for the flight controller and ESC stack. A stack that does not match the frame's screw holes does not fit, however good the individual parts are.

   The former Mode 2 FPV frames that used to sell from this domain show how tightly one frame decision cascades. The Kilowatt, a 3 inch frame with a 145 mm wheelbase and a 30 g unibody design, used a 20×20 mm FC mount and specified 13xx or 14xx motors: class, mount and motor size, all fixed by one frame. The Shredder shipped in two wheelbases from a single design, 220 mm for the 5 inch build and 280 mm for 7 inch, with the same low-deck layout and four press-fit nuts either way. Check the FC mount against the frame from step one before you order anything for the stack. Frame guides cover what the different geometries trade off.

3. 03

   Motors: stator size follows the prop, KV follows the cells

   Two separate decisions hide inside "picking a motor". Stator size, the width and height of the windings, follows the prop size fixed in step one: a 3 inch prop wants a small stator, a 5 or 7 inch prop wants a bigger one to turn a longer blade without overheating. KV, how fast the motor spins per volt, follows the battery's cell count, which has not been chosen yet at this point in the build. That is fine: fix the class and the frame first and the motor's two numbers slot in without guesswork.

   The Kilowatt's spec sheet shows the pattern directly: a 3 inch frame calling for 13xx or 14xx motors, a stator size range rather than one part number, because several motors in that range fit the same mount and the same prop class. Motors and ESCs covers how stator size and KV are read off a motor's own code.

4. 04

   Buy the flight controller and ESC as a stack

   The FC and the ESC do different jobs, flight control and power delivery, but buying them separately invites a mismatch: a 4-in-1 ESC with a connector the FC board was not designed for, or a current rating that does not match the motors chosen in the step before this one. A stack sold as a set is built to avoid exactly that, because one team designed both halves against the same mount pattern and the same connector.

   The ESC's current rating is not a free choice either. It has to survive whatever the motor and cell count from step three can pull, with headroom, because an ESC running at its rated limit under load is an ESC that eventually fails under load. Check the stack's mount size against the frame from step two before you order it. See flight controllers and motors and ESCs.

5. 05

   Radio and receiver: check the protocol before you order

   A transmitter and a receiver only work together if they share a protocol, and protocols are not interchangeable: a receiver built for one transmitter's protocol will not bind to a transmitter running a different one. This choice does not cascade from the frame or the stack, which is part of why it gets skipped, but it still has to be checked against whatever radio you already own or are about to buy, because a mismatched pair is unusable until one half is replaced.

   If this is your first radio, decide it once and keep it. It is the one part of the hobby that carries over between builds, unlike frames and motors, which get replaced. Start covers the beginner path through that choice in more depth.

6. 06

   Video: analogue or digital is a cost and latency decision

   Analogue video is cheaper, lighter, and has lower, more predictable latency, which matters when the gap between what the camera sees and what you do about it is the difference between a clean line and a crash. Digital systems trade that latency margin, plus the added weight and cost of more electronics, for a sharper picture. Neither is the wrong choice, but it should be made on purpose rather than inherited from whatever camera happened to come with a kit.

   This one does not cascade from the frame or the motor the way the earlier steps do, but it does add weight, and weight is what the battery step has to carry. Decide it here, not after the build is finished.

7. 07

   Size the battery to the build, not the build to the battery

   By this step the class, the frame, the motors and the ESC's current rating are all fixed, and the battery is the last thing they constrain: cell count has to match what the motors and ESC were chosen for, and capacity has to fit the frame's battery mount without pushing the all-up weight past what the motors can lift with margin. Buying a battery first and hoping the rest fits around it is the same mistake as choosing a motor first, just made one step later.

   Use thrust to weight to check that margin before you commit to a pack size, rather than finding out in the air.

8. 08

   Solder in an order you will not have to redo

   Joints that end up buried under other parts go first: power distribution pads and motor wires before the flight controller sits on top of them, the battery connector before the canopy goes on. Get the order wrong and you end up desoldering a joint that used to be accessible and is not any more, which is how a twenty-minute job becomes an hour.

   Work through the stack in the order the earlier steps fixed it: frame, then motors, then the FC and ESC stack, then the connectors that have to reach outside the frame. Frames and motors and ESCs cover the mounting details each part expects.

9. 09

   First power-on: props off, smoke stopper in, failsafe checked

   Connect the battery through a smoke stopper the first time, not directly. It limits current enough to give you a visible warning instead of a burnt component if something is wired wrong, and it should be done with the props off. Every check that matters at this stage, whether the motors spin the right way, whether the FC arms and disarms cleanly, whether the radio's failsafe actually cuts the motors when the signal drops, can and should be done before a single propeller goes on the aircraft.

   Props go on last, after every one of those checks has passed, not before. That is not a suggestion. It is the difference between a mistake that costs a soldering-iron burn and one that costs a finger.