But yeah...the airplane schtick might go over better if your plane was less menacing....I mean I get the whole flying tiger P-41 screaming in bit.. That may be giving them an idea of what your like in the sack too....guns a a blazing screaming in for the dive bomb action....and scream out.....wow...excitement there. I guess if you went with a 747 they might think you are trying to compensate for something. Sopwith Camel...well they may not be into multiple partner things.....I think you might just be at a loss with planes...maybe the reason you are getting a "meh" response is because women at the bar are generally not interested in planes....
And then hiding the phone number? Really? That picture would become the next coaster. If you are so "good" that you think you have to hide your number in the drawing and let the woman figure it out....then she is thinking "that dumb*** came up to me, who the heck does he think he is?!"
You would be better off scoping her out for a little bit...then doing a sketch of the bar that you are currently at. does not even have to be her in the picture, just the bar and maybe the bartender. It will be something she recognizes because she is sitting right there, and it is obviously something she is somewhat interested in because she came in there to begin with. If you really want to add class to the image, then you draw her at the bar and only her, no bartender. Then you have a line like "when I saw you at the bar I was inspired to draw what I saw" What she will notice is that it is only her.