First of all, I'm fairly new to electronics. I've been working on my own version of a miniature hovercraft just like this one http://www.thingiverse.com/thing:68639. I'm using an arduino pro mini for the controller, a nrf24l01 transceiver, small brushed motors (hubsan motors) running at 3 volts and a 3.7v 500mah 25c lips. I'm also using MOSFET transistors for the speed control. Here's the problem. I wired everything according to this page http://www.circuitmagic.com/arduino/run-small-brushed-motor-for-mini-quadcopter/, but when I turn the motors on, there's a huge voltage drop. When plugging one motor directly to the battery, it drops about one volt. When attaching two motors, the voltage drops down to 0.86 volts.
I don't know how to provide a steady 3.7 volts to my motors (without it dropping significantly), but I know it's possible since quadcopters like cheerson cx-10 runs four similar motors using a 3.7v 100mah lipo while I'm only using two motors. For that matter, how are micro quadcopters running multiple brushed motors without the motors running slow. I can only get a gentle breeze from mine. Please tell me if there's a way to regulate voltage or any other step or component I'm missing in my setup.