Apparently not - they force you to buy unwanted hardware.

I recommend you look at
Phoenix, http://www.phoenix-sim.com/welcome.htm
Reflex or http://www.reflex-sim.de/reflex-sim/shop/catalog/
Aerofly Pro Deluxe. http://www.aerofly.de/

All of which can be purchased without a controller - you just need to select an adaptor cable suitable for your Tx

I would recommend any of them over RealFlight anyhow. Bloatware.