Theoretcially and mathematically yes. However, you have to look at the dimensions and weight of the 4200 pack vs. the 2100 pack.
here is the 2100 pack:
Cell Specifications
11.1 volts
Length: 3.94in. 100mm
Width: 1.34in. 34mm
Height: 0.79in 20mm
Weight: 5.01oz. 142gm
Here is the 4200 pack:
Cell Specifications
11.1 volts
Length: 3.94in. 100mm
Width: 1.34in. 34mm
Height: 1.57in 40mm
Weight: 10.02oz. 284gm
The 4200 pack is twice the weight and twice the height. (1) make sure it will fit (2) that is one heavy battery, double the weight of the 2100 and almost 3/4 of a pound [:-] The heavier battery is going to throw off your C.G. and it is going to majorly affect the performance of the plane, it is going to fly slower and heavier.
Pulling less amps is a way to get more air time. Maybe going down a little in either pitch or length of prop is a better solution than getting an anchor for a bettery
