I have a Sainsmart Jr mini DIY drone kit. It has 4 rotors and they all spin but the drone simply does not take off. Any suggestions appreciated.

 

Can you show us photos of the drone and a link to the kit assembly manual?

Here are some possibilities:
1) The rotors are not properly installed with regards to CW and CCW rotation.
2) The polarity of the motors are incorrect.

 

Thanks. The possibilities 1 and 2 - are they the same - i.e. if polarity is not correct, CW and CCW rotation would also be incorrect?
Sorry for the typo- should be Sainsmart not Sinsmart

 

I have a Sainsmart Jr mini DIY drone kit. It has 4 rotors and they all spin but the drone simply does not take off. Any suggestions appreciated.

The most likely cause is a bad battery.
How old is it?
Do you have a good charger for it?
What is the voltage across he battery terminals at full power?

 

Sorry for the typo- should be Sainsmart not Sinsmart

Title corrected

 

It is new, batteries good as the 4 rotors really turn at full speed, but does not take off.

 

It is new, batteries good as the 4 rotors really turn at full speed, but does not take off.

Hoe do you know that the batteries are good? There is obviously not enough power there to become airborne. Have you measured them under load?

 

As suggested somewhere above, check you propellers

https://dronesgator.com/how-do-drone-propellers-work/

Edit: re reading, I found it


/Edit

 

Thanks this really helped and it flew. I damaged a prop in the process and wonder where I can get spare props?

 

As suggested somewhere above, check you propellers

https://dronesgator.com/how-do-drone-propellers-work/

Edit: re reading, I found it

View attachment 271945
/Edit

Anyone know where I can get spare propellers? Buying a new drone too costly.

 

Anyone know where I can get spare propellers? Buying a new drone too costly.

Every drone is different and uses different propellers.
Can you post a picture of the drone and close ups of the propellers?
Try Sayal Electronics.

 

Have you tried contacting the seller or manufacturer? Slow I know, it's likely the only way to get it done I just noticed this thread started last year.

 

Anyone know where I can get spare propellers? Buying a new drone too costly.

It did work after your suggestion, then one prop broke which I replaced, then stopped working although all props rotate. Here is a pic

 

I think that your propellers are in the wrong locations and wrong orientation.

(1) Note that the red and black blades ought to be angled in opposite directions.
(2) Note that there is a top side and bottom side of the blade.
(3) Usually, the red props are on opposite arms and the black props on opposite arms.
(4) Check the rotation of the motors. You need to have the props spinning to provide lift, i.e. to blow air downwards.

Edit: This photo shows that the same coloured props are not opposite, i.e. ignore (3) above but check (4).

 

In this photo, as far as one can tell, the props are not consistently colour coded.
The black rotor on the left and the orange rotor on the right need to rotate in a counter-clockwise direction.
The other two rotors need to rotate in a clockwise direction (looking from above).

 

Like your drone, my cheap little drone has two white propellers on its front and two black propellers on its rear so we can see the forwards and reverse directions. The same colored propellers spin in opposite directions and propellers on opposite corners spin in the same direction.
My drone is in a lightweight cage so it can bounce away from a wall or the ceiling without stopping or breaking a propeller.
It uses infrared remote control. My drone battery is charged from a USB cable.