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Flight performance

Technical Specifications for the Rocrow:

(and all the small sized models in general!)

Technical specs non airbrake Rocrow:
Material body fin and wing EPP
Material head PU
Material of the plastic parts Nylon
Wingspan 930 mm
Length 580 mm
All up weight 640 g +20 g for the sensors
Surface area including tail 0.275 m2
Wingloading 0.2327 g/m2 + 0.0073 g/m2 for the sensors
Flight time 5 minutes full throttle, 10 minutes half throttle
Max range 1.4 km
Max LOS 300 meter
Max climb rate 4.2 m/s
Sink rate 1.36 m/s
Maximum ground speed 91.5 km/hr
Minimum ground/cruise speed 36 km/hr
Power to weight ratio 1:0.625
Maximum level of acceleration 0-80 km/hr 7.1 sec
Aspect ratio 4

 

Technical specs airbrake Rocrow:
Material body fin and wing EPP
Material Head PU
Material of the plastic parts Nylon
Wingspan 930 mm
Length 580 mm
Airbrake weight 41 g
AUW 680 g + 20 g for the sensors
Surface area including tail 0.275 m2
Wingloading 0.2472 g/m2 + 0.0073 g/m2 for the sensors
Flight time 5 minutes full throttle, 10 minutes half throttle
Maximum range 1.4 km
Maximum LOS 300 meter
Maximum climb rate 3.9 m/s
Sink rate 1.55 m/s
Maximum ground/cruise speed 72 km/hr
Minimum ground speed 41 km/hr
Power to weight ratio 1:0.588
Maximum level of acceleration 0 – 70 km/hr
Aspect ratio 4

The following measurements are recorded with both a barometric sensor measuring air pressure and a GPS to measure ground speed, both sampling with an update rate of 10 Hz. With graphs we are able to review the flight data to get a better understanding of the performance of the Rocrow models, allowing us to accurately match the Roprey to the live predator.

 

The addition of the airbrake adds 35g. This increase is negligible when flying fast, but more noticeable when trying to fly as slowly as possible.The maximum range has been tested in a dry climate, using LOS (line of sight). At 1.4Km, the Rocrow still does not experience an unstable connection or suffer any signal drop outs. A fluid motion in the servos is maintained. 1.4Km is hugely within the range required for falconry, bird deterrence, and RC enthusiast flights. We have not measured the read signal strength indication (RSSI).

Weather conditions for the flight data below have been measured in wind strengths of less than 1-1.5 km/hr (0.3-1.5 m/s). Measurements related to surface area and dimensions are based on our 3D drawings.

Flightdata – Rocrow without airbrake:

Maximum climb rate in m/s:

In the first graph it can be seen that it takes around 40 seconds to climb from 30 to 170 meters, equaling 3.5 m/s. In the second graph you can see the climb rate already set out against the altitude, which is also maxing out at roughly 3.5 m/s.

 

Sink rate in m/s:

85 meters in 62.5 seconds = 1.36 m/s

It’s interesting to see that tailwind or headwind does not affect the sink rate.

Minimum ground/cruise speed km/hr:

In this graph, barometric altitude vs GPS speed can be seen. Instead of counting and takeing an average of each data point, two blue lines can be seen that represent the maximum and minimum ground speed. The pink line represents the average ground speed of 36 km/hr.

 Maximum ground speed km/hr:

The maximum ground speed has been measured with headwind and tailwind. As mentioned before, wind conditions were below Beaufort 1. Altitude, in red, has been set against the GPS speed. Because the launch is included you can see it takes almost 10 seconds to get to the maximum speed, but eventually maxes out at 85 km/hr. With the tailwind it’s maxing out at 97.5 km/hr which averages out at 91.5 km/hr max ground speed

Power to weight ratio:

In this case we measure power as thrust. The model is on a weighing scale and giving full throttle down into the scale gives a reading of 400 g. This on 16.4V. The all up weight of the model is 640g. 640g:400gr thrust=0.625 or 1:0.625. This means that the Rocrow cannot do vertical climbs which has been covered in the maximum climb rate graph.

Maximum level acceleration 0-80km/hr:

8.7 seconds in headwind:

 

 

Since the speed did not exceed 80 km/hr the amount of time for 40 km/hr was taken and doubled.

2.75 sec x 2 = 5.5 seconds. Which averages the acceleration speed at 0-80 km/hr in 7.1sec

Flightdata Rocrow with airbrake:

The airbrake adds 35 g to the model. Let’s find out how and if it’s affecting the flight performance.

Maximum climb rate in m/s:

In the first graph you can see that the average climb rate is roughly 3 m/s. It takes around 37 seconds to climb from 30 to 170 meters, that is roughly 3.78 m/s. Interesting, since the airbrake weight should decrease the climb-rate. Let’s do this again, but now over a longer period of time, see second graph. It takes 53.5 seconds to climb from 14 to 205 meters, that’s 3.57 m/s. In the second graph you can see the climb rate already set out against the altitude, which is roughly maxing out at 3 m/s.

 

Sink rate m/s:

The sink rate is measured starting from an altitude of 98 meters, decreasing to an altitude of 35 meters which takes 65 seconds. The sink rate over this period of time is 1.45 m/s.

Minimum ground/cruise speed km/hr:

Here you can see the barometric altitude compared against the GPS speed in the same graph. Instead of counting and taking an average of each data-point, you can see 2 blue lines representing the maximum and minimum ground speed. The pink line represents the average ground speed of 41 km/hr

Max Ground Speed km/hr:

Graph comes shortly.

 

Power to weight ratio:

In this case we measure power as thrust. Placing the model on a weighing scale and giving full throttle vertically down into the scale gives a reading of 400 gr. This on 16.4V. The all up weight of the model is 680g. 400g:680g=0.588 or 1:0.588. This means that the Rocrow cannot do vertical climbs which has been covered in the maximum climb rate graph.