Brief

At WARG, most of our drones are broken down into independent subsystems, which often incorporate multiple sub-teams. This page is broken down into these subsystems, with a brief description of the constituent components of the system, and how to configure them. For the functionality and alternatives, please consult the respective Sensors, RF Devices, or Propulsion documentation pages.

Please use this document as a guide and reference point for creating your pre-flight checklists! Do not use it as your pre-flight checklist.

Propulsion System

<< The propulsion system relates to all mechanical and electrical hardware that contributes to generating lift to fly the drone >>

All quadcopter propulsion systems constitute of a few basic parts, but what you see on Houston may not always directly translate to what you see on our next drones! Keep that in mind as you go through this document….

Power Supply

Houston’s batteries are type 3s 4000mah! The full product name is:

Turnigy nano-tech 4000mah 3S 35~70C Lipo Pack w/XT-60

They have soft velcro on the backside, and may be dated YYYYMM##, where YYYY represents the year, MM represents the month, and ## represents the number of the battery within the batch.

Battery Monitoring

Battery Monitoring on most warg airframes are taken care of using Holybro PM02 Power Modules. On Houston, we are using an analog power module saved from Icarus, which means that it has a few curious points to note:

• It has XT90 connectors, to which we have attached xt60 adapters (since houston is all xt60).

• It must have the correct calibration in software, and this could be affected by adverse weather.

• The current monitoring is no longer accurate.

Please follow Ardupilot documentation, for configuring the power module:

• BATT_VOLT_MULT 18.812

• BATT_AMP_PERVLT 36.364

• BATT_MONITOR 4

Power Distribution

Power comes in, power comes out. On Houston, this is handled as part of the frame! Note the XT60 connectors coming off of the bottom plate towards the ESC’s.

Note the 5th power lead coming out from the side of the pcb! This is typically where you would plug in your power supply, but all positive and ground terminals are connected to each other. Any additional wiring must be the same gauge or thicker.

Testing & Checking

Before you plug anything into your PDB, you should check for continuity on all voltage and ground rails! Do this using a multimeter, and make sure that all positive rails are connected, and likewise for the negative rails. Make sure that the positive rails are on the XT-60 are on the flat part of the connector.

Electronic Speed Controllers (ESC)

Houston currently uses unmarked “opto” ESC’s. These are leftovers from WARG “spare” and “parts” drones, and only accept a PWM signal. Newer revisions of Houston should use opto dshot ESC’s.

These ESC’s are currently soldered directly to the motors, but in the future will use 3.5mm bullet connectors. Motors typically use 16 AWG wire.

Motors + Propellers

Motor selection is always tricky, but keep in mind the basic principles of motor selection regarding stator volume (diameter vs height), and kv rating! Motor selection is also tied in very closely to propeller selection, so we include this together.

Currently, houston uses 2217 950kV motors. The full name of the motors is

Cobra CM-2217/20 Multirotor Motor, Kv=950

These are, slightly, slightly, underspec for 3s, but are fine for our use and are also carryover from spare and parts. You can find the datasheet for the motors on the cobra motors website:

innov8tivedesigns.com/images/specs/Cobra-CM-2217-20-Specs.htm

Please keep in mind that Houston’s frame only accepts 16x19mm motors.

< Technical drawing here (if possible) >

Tuning for motor/prop combinations

All motor+propeller combinations react slightly differently, so when changing configurations, it is recommended to switch back to defaults, by using the “initial parameters” tab and re-updating the tune. See Software Configuration for more info.

Flight Dynamics System

Flight Computers

Houston currently uses a pixhawk 5x which has been fully configured, but can accept any regular flight controller. Make sure the orientation matches with Red to left and White to right.

PWM ESC’s can be plugged into any port, but DShot ESC’s must be plugged into FMU or MAIN out. Using “IO” or “AUX” will not work. See software configuration for more information.

Communication Links

There are 2 RF links on houston, one for RC control, and one for telemetry. Both of these currently exist on different frequencies, but can easily be changed should you desire. Remember to configure the software properly when you do so.

Both airside antennas use U.FL connectors (someone please correct me if wrong).

Control Link

The current control link is a 915 frequency TBS Crossfire system. The full name of the airside receiver is:

TBS Crossfire Nano RX

This receiver is mounted on the back-left arm, with the dipole antenna mounted vertically on the aluminum leg. This is done so that there is optimal signal in any orientation (review your antenna radiation patterns kids!). Be careful not to damage this antenna when working on the drone.

Telemetry Link

The current telemetry link is a 2.4 GHz ELRS link, configured to do bidirectional serial passthrough, connected to TLM1 port. The receiver is a standard serial receiver, soldered directly to a 7-pin connector.

Sensors

Houston is quite simple, so there’s really only 1 mandatory sensor, which is a GPS! This is critical for position-hold flight modes. It is mounted on top of the drone, and plugs directly into the GPS1 port.

Optional Sensors

for optional sensors, please see the sensors information page for the other possible sensors. Most of these can be configured on houston should the need arise.

Payload

The “payload” refers to anything which sits in the third tray of Houston. Currently this is the 200$ camera, an FPV camera, and the Jetson.