[Mmarciniak]

Hey I'm looking for a little help I have built a replica qav250. I have all of the motors spinning the correct direction and the props mounted correctly. When I go to take flight, the motors just spin at a crazy rpm and the drone does not take flight.

Anyone have any ideas on what else it could be?

Max

[mr_w]

Where does the air go? Is it pushing air up or down?

What kind of props you have? You might mounted them upside-down, while they still seem to be spinning into the right direction, they might have trouble creating enough air-flow if they try to push from the wrong side of the blade.

[TheOtherCliff]

Props must be the correct size and that depends on size of motor, KV of motor, and number of cells in LiPo pack.  There is also a very small possibility that the ESC's need calibrating.

[Mateusz]

Like others mentioned
- Usually this problem for most people is either wrong motor direction or prop type side.
- Less likely bad ESC calibration
- Even less likely thrust to weight ratio. Maybe to heavy battery and build ? Check motors specs to get info on thrust with specific props. Compare to weight of your aircraft.

[andycrawforduk]

Put full spec of build motors prop size etc

Sent from my SM-G903F using Tapatalk

[Mmarciniak]

This is the kit I bought on amazon

https://www.amazon.com/gp/aw/d/B010FMGUS8/ref=mp_s_a_1_4?ie=UTF8&qid=1485882513&sr=8-4&pi=AC_SX236_SY340_FMwebp_QL65&keywords=drone+kit&dpPl=1&dpID=51wgsyIpNOL&ref=plSrch

Yes I have the props facing the right way. The air is pushing towards the floor.

[TheOtherCliff]

The props will push air towards the floor whether you have them on backwards or not, but it will only blow 1/2 as hard if on backwards.

Imagine a prop with no airfoil curve in the blade.  The blade sits at an angle.  Rotate the prop 180 degrees to put it on backwards and you rotated the blade 180 degrees also.  The blade still forces air downward.