to drill steel use heavy feed, low speed and lubricate, lubricate, lubricate. Use cutting oil to keep the hole well lubed. And oh yes, a dremel really isn't meant to drill through steel as you need to bear down on it pretty hard the motor isn't designed for such heavy applications. The dremel instructions in fact tell you not to use pressure but to use the speed of the motor, this is contrary to the requirements of drilling steel. Aluminum you can use higher speed, but if your 100% sure it is steel you are drilling then you need to get an actual drill motor for the job. I can't think of any steel parts needing to be drilled on an RC plane however.