Motor: This machine is designed specifically for 1407 or similar sized motors. 1806 or 22xx sized motors are too heavy and large for this frame. Keep in mind the 4R is designed around having as little mass as possible. 1806 or 22xx motors will fit but we recommend against using them. A large heavy motor will not produce the best race performance results with the 4R. 

(Brother Hobby 1407-3600kv) or similar 

Electronic Speed Controller: If you plan to run 4s lipo voltage a 20amp ESC is all you need. Since this machine has drastically reduced mass the motors do not need to be as large. This means the current draw is also low. You can use single ESC's mounted out on the arms or a 4-in-1 ESC/PDB combo. If you use a 4-in-1 the unit will need to be oriented so the ESC tabs face the left and right sides of the frame (like in our pics on the product page). Not front to rear. This is due to space constraints. 

X-Racer Quadrant 25a 


LB20a (PRO)

Flight Controller / PDB Considerations: In order to achieve the lightest frame possible we had to pack everything into a tight space. For this reason you must choose a specific type of FC / PDB. A standard FC (36mm x 36mm) will fit but only if you match it up with this specific mini PDB (Matek Micro PDB). Another type of FC that will fit is a micro FC/PDB combo like this (Piko BLX). Yet another option is to use a 36mm x 36mm FC/PDB combo like this (Kombini). The final type of configuration that fits is a standard sized (36mm x 36mm) FC and 4-in-1 ESC combo. Again, a standard sized FC matched to a standard sized PDB WILL NOT FIT

Lithium Battery: The 4R uses a battery that is smaller in capacity and weight than a 5" or 6" racer. Due to less amp draw a larger pack is not required and we suggest against using anything over 1000mah. Ideal battery sizes and capacities are below. The 4R is designed for racing so your target flight time under full load should only be 2:30. 

850mah 4s Lipo

1050mah 4s Lipo

800-1050mah 5s lipo

FPV Camera: Either a CMOS mini cam or HS1177 sized camera will fit. For the racing purist looking to be as light and nimble as possible go with a mini cam. 

2.8mm Mini Cam

1.8mm Mini Cam

Runcam Swift (RR)


FPV Video Transmitter: Most standard sized racing VTX will fit. 

TBS Unify Pro HV Race

Hawkey 200mW