Backstory

I recently acquired a ZOHD Drift. It’s a very convenient FPV airplane. It has a 877mm (34.5 inch) wingspan, weigh between 240-300 grams (depends on battery size), and is a very gentle low speed and easy to fly cruiser. I’ve already flown it with a 3s 850mah lithium polymer (LIPO) battery with a 3 bladed 3×5 propeller. With this setup it would fly for 20 minutes. 20 minutes is plenty of time for most flying, but I decided I wanted to go for much longer endurance for kicks and giggles.

Setup

To achieve a longer endurance, I changed the battery to a 2s 3500 lithium ion (LION). This is a lower voltage pack and so the motor would be spinning slower. I changed the propeller for a larger 2 bladed 5×3 propeller. Since I went to lithium ion instead of lithium polymer I had to reprogram the ESC to allow for a lower cutoff voltage.

Here’s a picture of the two propellers side by side.

Amp Tests

With the throttle at 100%, the aircraft draws around 7.3 amps

However realistically I expect to cruise at around a quarter throttle, which pulls around 1.3 amps. With a 3.5 amp hour battery, this could give 2.6 hours of flight! However the load changes in flight, and I wouldn’t be at 1/4 throttle the whole time. No better way to test than to just fly it.

Flight

I conduct my flight 3/2/2021 during a break I took from work. The temperature was about 50 degrees and the winds were around 5 knots Really a nice day.

I did today’s flight with FPV with my Skyzone 04x goggles and Frsky Xlite transmitter with R9 module.

Result

Well I got a 45 minute flight out of it! Turns out the DVR in my goggles didn’t record (would be a pretty boring video though). The only reason I ended the flight early was because I had to get back to my job. However my charger only put back 1600 mah back into the battery. Considering it has a 3500 mah capacity, reaching 1 hour should be no problem. A 1.5 hour flight time might be possible!


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