We had a chance to perform a load test on the Crossbow this past weekend. We’ve added additional cable supports and a landing apparatus which helped reduce the torquing issue evident in the initial test flight. We’ve decided not to reduce the chassis weight at this time because the extra weight will help us with load testing. 

The weather conditions during testing was a bit windy at about 8 mph, but since we weren't planning on doing more than 3-4 ft hover mode, we continued with our tests. 

During the first flights, it was evident that the initial torquing issues had been reduced significantly. The landing apparatus is made of 2" PVC piping and attached to each pair of arms like an outrigger. It was strong enough to counteract the torquing effect yet flexible enough to reduce landing impacts. 

The hover tests were successful and didn’t seem to tax the chassis and motors much at all. Towards the last test flights of the day, we decided to increase the takeoff weight by adding sandbags to simulate a partial load. The total take off weight has now been increased to 138.8 lbs (62.9 kg).

After clearing the area and going over pre-flight safety checks, I decided to do a light hover where the airframe was still in contact with the ground, but the motors were working hard enough to yaw the drone and pivot. This allowed me to “trim" the controls (micro adjustments) to respond better to the current wind conditions. After I've trimmed the controls and the drone was stabilized, I was ready to proceed with the hover test under load (138.8lbs / 62.9 kg).

As I increased the throttle, the loaded airframe slowly lifted off the ground. At takeoff, it seemed as if the motors were applying significant effort under the load, but after the entire airframe lifted off the ground, the motors did not seem to be applying much effort at all. 

All-in-all, the test was quite successful! Our next step is to take all the data we’ve gathered and improve upon the electronics as well as the overall structural design. 

I will also start developing concept designs and sketches to illustrate how the fairings will look as we work towards the final design. Stay tuned!

Maroon Vault