This is a sub-page of our post on miniquad propeller thrust tests from the back of a truck. Please click the link to read the full article if you landed here.
Some notes on the plots in this post:
- If you are on a computer, you can view the data points by hovering over them. This also applies for legends which have been cut off.
- Check them out on a desktop computer! Mobile phones will work but you’re going to have a hard time seeing the legends and may have issues loading the page.
- Two plots are included for each prop: Thrust and Efficiency. Thrust is in kilograms (kg). Efficiency is in grams per watt (g/W). Efficiency was cut off before the prop starts to generate thrust, which is quite late in the test for higher speeds.
- The x-axis is time in seconds since the start of the test.
5″ Props Compared
The first comparison I put together is all the 5″ tri-blade props that I tested.
This is the performance of each prop at a full stop compared with each other. The first graph is thrust in kilograms, the second is efficiency in grams per watt. You can see from this chart that there are some problems with the data because there is no way that the HQProp 5x4x3B beat out the DAL Cyclone or the RaceKraft 5051 at static thrust. It should not be a surprise that the 4″ pitched props are the most efficient of the group at static thrust.
The is the performance of each prop at 25MPH. You can see the spread starting to fill out as expected – with higher pitch props beating out props with 4″ pitch, despite the errors seen in the static thrust tests. 4″ pitch props still do quite well in this environment, though.
And here is the performance at 50MPH. The gap between 4″ props and the rest becomes quite large here, with most of the high pitch props producing nearly twice the thrust of their 4″ brethren at this airspeed. I find it interesting that in this test, efficiency is climbing until the throttle hits 70%. I really wish that I had been able to hit 100% throttle for all these tests to see if that trend would have continued. The clear winners of this test are the DAL Cyclones and the HQProp Durable 5x5x3, which both put out impressive thrust and efficiency figures.
Blade Diameter Compared
In the next comparison test, I pit 4 props with the same blade count and pitch but different diameters against each other. Here’s how they stacked up:
Once again, the HQProp 5x4x3B does unnaturally well in the comparison – the test for it must have been done in zero wind (or even a slight tail wind). Otherwise, this lines up with what you would expect.
Pictured are the results from the 25MPH test.
And here is the 50MPH test. As you can see, the spread stays fairly constant for all props. This makes sense as the larger props have longer blade tips that can better cut through moving air, but also create more drag while in a headwind. It appears that in these tests the forces cancel out. The efficiency graph reinforces this story – more drag means more power required and efficiency will drop. The larger props get less and less efficient compared to the smaller ones as the airspeeds increase. I am not sure why the 3″ prop shows so much flux in this last graph.
Blade Count Compared
The last comparison test I put together compares the effect of blade count on prop performance. For this test, I selected 6 props: the RaceKraft 5038 and 5051 were natural to pit against each other. The HQProp 5x4x3B and 5x4x4V1SB were also natural competitors. The Gemfan 5045BN lines up closest with the DAL TJ5045 in terms of blade profile and pitch.
Again, the HQProp 5x4x3 is performing a bit too well and the RaceKraft props seem to be performing overly poorly compared with other static tests, both are likely due to wind. Efficiency-wise, low blade counts beat high blade counts, as expected.
A couple of things are happening here: the RaceKraft props assume the top and bottom of the charts, respectively. The Gemfan 5045BN and the DAL TJ5045 keep roughly the same spread as in the static test. Interestingly, the 4-bladed HQProp loses ground over the 3-bladed prop, however. Efficiency is as expected, with the exception of the RaceKraft 5038, which performed particularly poorly in this test.
The trend continues – the RaceKraft 5038 continues to pick up ground, while the HQProp 4-bladed continues to lose out to the 3-blade. This lines up with the stick feel I’ve gotten from high-blade-count HQProps: they feel great on the punchout seem to lose their “bite” quickly. Efficiency continues to prefer low-blade count props.