I´ve did a small numerical exercise in order to improve the flight time for an electrical quadropter.

I did for a family of 5 quadropter weights from 500g to 1.5Kg, dry mass, (without battery).

The hipothesis are the following:

- power consumption is linear with total weight: Watts = 0.15 * weigth(gr). The ratio is taken from tests on my quad (730gr , 110 wat)

- battery weigths taken from Zippy & Turnigy Lipoly 3S 20C data at HK (average wights for a standard model) It can be expressed as: Batt Weight (gr) = 0.0688*Capacity(mAh)+26.5  )

The result is the following table:

• The slope of each curve decrease when quad weight increase. That is, for larger quads you need to increase more mA for same increase of flight time duration, than for smaller quads. For example, to increase from 7.5 min to 10 min you need to pass from 1000mAh to 1400mAh in a 500g quad ; and pass from 3000 to 4000mAh in a 1.5Kg quad

For example a quad of about 500gr (dry) with a battery of 2200mA is very good compromise, reaching about 15min flight time. In fact, one of my quadropters about these data, reached 17.5min continous hovering flight with a battery of  2250mA.

Attached is the excel file, if someone wanst to play more.

Hope you like

Angel

Note. This is an update of initial issue with better data (averaged) from comertial battery weights

flight time.xls

#### Replies

• I would have tought that a hexa is way more better than a quad or tri.

I thought the more motors share the weight, the less power consumption there is. Especially if I try to speed up and break..more motors can handle it more effective.

Did I make a mistake in my thoughts?

• Really nice work.

• Hi. For what I can understand from the graph and table, even if the 500gr is a good compromise, it looks like the heavier it gets, more efficient it gets too. The 1500gr model with 4400 battery does not consume 3x the power of the 500gr model, and the flight time is more than 1/3 of the 500gr time. Is that correct ?

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