C-Astral Bramor PPX

 C-Astral Bramor PPX

The Bramor PPX is a fixed-wing, catapult-launched, parachute recovered, unmanned aircraft that is operated fully autonomously. In order to conduct flight operations with this aircraft, the flight crew uses software called C3P to create missions/grids. Much like the flight planning tool in Measure Ground Control seen earlier, the flight crew can create specialized missions for any situation. In this lab, I became familiar with the nuances and specifics of this software in order to better my understanding of the aircraft. I will go through some of the main functions throughout this post.

Parachute Folding

One of the largest components of preparing the Bramor PPX for a mission is the parachute. In order for the aircraft to land without damage, the parachute must be folded and packed well. If the parachute is not, the aircraft runs the risk of failing to slow down fast enough before hitting the ground. One of our biggest tasks for learning the aircraft was understanding how to fold the parachute. The video below is one that I made with a partner showing our knowledge.

(Figure.1 Parachute Folding Video)

Mission Planning

A very common theme for UAS operations is mission planning. This is because there is a vast number of possible unknown conditions that can appear during a mission. Ensuring the the flight crew is aware of as many conditions as possible and planning in their favor can create a safe and efficient operation. Below is a list of various things that the flight crew should be aware of before departing.

• Know the study site
• Know the vegetation
• Know the terrain
• Check the map for possible man-made obstacles
• Check the weather
• Check all of the equipment such as batteries

When the flight crew arrives at the location they should do many of the same checks as before but also go further in detail to check the flight area. 

• Wind speed, wind direction, temperature, dew point
• Assess the vegetation
• Assess terrain
• Asses power lines, underground cables/metal, and power stations
• Collect the elevation of the launch area
• Create teams and groups
• Reevaluate Missions
• Confirm cellular network connectivity

C3P Software

The C3P software allows the user to create a specialized mission for their needs. There are many options and tools that can be used to ensure just that. Below is an outline of a test mission that I created with various specifications from the lab assignment. 

Mission #1: 

Altitude - 125 meters (Relative to Terrain)

Frontal overlap - 80%

Sidelap - 75%

Camera - RX1R II 35 mm

Overshoot - 150m

(Figure.2 Mission #1)

(Figure.3 Mission #1 Settings)

Mission #2: 

Altitude - 125 meters (Relative to Terrain)

Ground Sample Distance - 2.5cm/pixel

Frontal overlap - 80%

Sidelap - 75%

Camera - RX1R II 35 mm

Overshoot - 150m

(Figure.4 Mission #2)

(Figure.5 Mission #2 Settings)

These two missions are very similar in terms of overshoot, front lap, sidelap, etc. The biggest difference, however, is the change in GSD. According to the C3P manual, GSD is "the distance between two consecutive pixel centers measures on the ground." By increasing the GSD the altitude is also increased automatically. If the altitude is too low for the selected GSD it will increase the height to make up for the difference. 

Another thing to note with these flights is the change in flight lines depending on the altitude selected. In mission #2, raising the GSD also raised the altitude which in return decreased the number of flight lines. This is because the higher the altitude, the more that the sensor can pick up in a single image. Understanding this concept is important when planning missions and knowing the quality of images that you want.

Lastly, the overshoot of these missions is important to understand. Unlike a quad such as the Mavic 2 Pro, the Bramor PPX is a fixed-wing aircraft which requires ample space to be able to turn around. In the above figures, you can see a pointed shape outside of the blue lines on the north and south side of the flight plan. This is the path that the aircraft will take in order to make a 180-degree turn. Increasing the overshoot will give the aircraft more space while decreasing the overshoot will give the aircraft less space. Understanding this and planning for the flight area is important in allowing enough space for the aircraft to make its turns.

Mission #3: 

Altitude - 300 meters (Relative to Terrain)

Frontal overlap - 80%

Sidelap - 75%

Camera - RX1R II 35 mm

Overshoot - 100m

For this mission, when setting the wind direction a purple area appeared on the map close to the landing point. The wind was set to 5.3 m/s moving in the southeast direction which is fast enough to cause some error in the exact landing point. The purple area is the estimated landing area with the wind speed calculated in. (Figure.6) After this, I increased the wind speed to 9.7 m/s and changed the direction to northeast. The circle moved when these changes were made. This feature is very useful for mission planning. For example, let's say that we are not in an open field and we only have a small portion of open area for landing while the rest of the site has trees everywhere. When setting the landing point we want to ensure that the aircraft floats down in the open area. With this tool, we can now calculate the general area the aircraft will come down. 

(Figure.6 Mission #3 Landing area with wind - 5m/s & 300 degree direction)

(Figure.7 Mission #3 Landing area with wind - 9.7m/s & 194 degree direction)

After practicing with all of these features I actually ran the flight within the simulation to use some of the in-flight features. Throughout the flight, the user has some tools they can use to control the aircraft in case of unpredicted circumstances. The first tool, "Rally" sends the drone to the rally point that was previously specified and flies in a circle around that point. The rally tool is useful in the case that there is an issue with the flight crew and they want to keep the drone in the air but not continue the mission. The second tool, "Loiter" does a similar function as the rally tool except the drone will just circle at the current location instead of heading to the rally point. Furthermore, the "Home" button sends the drone back to the home position in case of an error or the need to relaunch the aircraft. Lastly, and possibly the most important, is the "Parachute Pop" button. This button deploys the parachute when the PIC presses the button. This is important for any emergency or scenario in which the aircraft needs to be landed. This can range from failure of motors to the wing spars coming loose and a wing falling off. Below is the flight summary from the simulation (Figure.8)

(Figure.8 Mission #3 Flight Summary)

All of these tools combined during a flight can ensure that the flight crew has effective and efficient control over the aircraft. There are many unforeseen events that can happen during a flight operation in which the crew will need to utilize these tools. For example, a crop duster takes off while you are flying in a nearby field. You are unaware of his flight path so you set the aircraft to loiter while you get a better idea of his pathing. 

Reflection

For UAS operations, mission planning is one of the most important aspects and should be taken seriously. Studying your equipment, the flight area, and the software can ensure that your flights are always conducted safely and efficiently. In the UAS industry, those two things are the deciding factor in success and failure. Pre-flight checklists are an essential aspect of mission planning. These checklists should be followed very closely to ensure every step is covered. For example, during a mission, this semester flying a Mavic 2 Pro, my partner and I went through the checklist but missed over a couple steps. Upon trying to takeoff we remembered that we had failed to insert the SD card into the aircraft. Luckily Measure Ground Control warned us about this before we could take off. While this is not a dangerous mistake, if we would have payed a greater amount of detail to the checklist this could have been avoided. In the future or with larger drones, mistakes like this could mean a redo or even an accident. Understanding the flight area is also immensely important before going to the field. Using software like ArcGIS, flight crews can study the area and look out for any possible obstacles that need to be monitored. Furthermore, the flight crew can identify landing and take-off locations to save time before going to the field.  All of these coupled together will ensure that the flight crew is operating with the utmost level of safety and efficiency.