Flat bottoms generate much higher levels of life at the same speeds.

If your are having problems lifting off with the syms you might have the following issues:

1: Your reciever armed improperly.
Correct arming procedure:
-When plugging in your helicopter make sure your TX throttle trim is set to the lowest possible setting. As well your stick should be at the lowest position.
-Once the reciever arms and goes green, move the trim back up to mid-point just below the mid-point before you hear the blades try to spin.
This will give you the full range of throttle.

2: Your blades are not at 0 pitch.
Correcting blade pitch:
- Unplug the main and tail motors from your reciever.
- Move the throttle trim on your reciever to the mid point and flip the idle up switch on.
- Move your throttle stick to the mid point.
- At this setting your blades should be at 0 pitch, if your pitch is off (your blades are tilted up or down) adjust the pitch links until they are at 0 pitch.
- Once both blades are adjusted to 0 pitch verify by swinging both blades to one side and checking that the blades are on the same line with each other.
- You should not have one blade high and one blade low.
- Reinstall everything and spool up, be sure to adjust tracking before your first official flight.