jdetray

Hi Pete -

As you might guess, flight time depends on many factors: the type of plane, throttle management, your style of flying, etc. For example, a 3D plane that spends a lot of time hanging from the prop is generally going to consume battery power a lot faster than a slow flyer cruising lazily around the sky.

If you know a couple of numerical vales about your power system, you can at least estimate the flight time.

Formula for Run Time

run time in minutes = (Battery Capacity in Ah/Motor Current in A) x 60

This is just a rough guide, and it requires that you know approximately how much current your power system draws. A wattmeter will tell you. The formula also needs your battery capacity in Amp Hours (Ah). Divide mAh by 1000 to get Ah.

The simplest method is to measure your current at full throttle and use that number in the formula. In reality, you probably won't fly at full throttle all the time, so your average current usage probably will be less than the full-throttle value. Also, a power system will often draw less current in flight than it does during ground testing.

So if you use the full-throttle current in the formula, it will generally give you a worst case flight time. Actual flight time will usually be greater.

I've included some examples below.

- Jeff


Here are some examples.

Example 1:
5000 mAh battery
power system draws 50A

5000 mAh = 5 Ah

5/50 x 60 = 6 minutes


Example 2:
5000 mAh battery
power system draws 35A

5000 mAh = 5 Ah

5/35 x 60 = 8.57 minutes