While your plan is theoretically possible, it is not practical. There are many reasons why this is true. Here are a couple just to warm up:
1. Your motor is probably designed to operate at either 1750 rpm, or perhaps 3,400 rpm, in round figures. In order to make it produce any meaningful amount of electricity, you will have to turn the shaft that fast. A "propeller" (it's not really a propeller) of the right diameter could never go that fast in any reasonable wind. So that means you now need a weatherproof, low friction, low maintenance transmission to gear up the prop shaft to the motor shaft. Not a trivial job.
2. To get decent clean air, which is air that has not been made turbulent by nearby objects like trees and houses, you have to put your mill above all that. How tall is the tallest tree around your house? Now, make a tower to support your new mill 20-40 feet above that if you want decent power output. Oh yeah, and it has to be strong enough to survive the strongest wind that will happen in the next X years. If it fails, what will that 40-100 foot tower land on? Your house??? This is no fault of your washing machine motor idea, just that you have several major obstacles to overcome to get decent power output out of ANY wind turbine.
3. Have you thought about how to keep your new mill, and it's fancy transmission, pointed into the wind automatically? And how do you bring the power down the tower on some kind of wires, yet still allow the mill to follow the wind without twisting up the wire/cable? You could build or buy slip rings, but they are often problematic and may require periodic service. How are you going to get the mill up and down that 40-100 foot tower on a regular basis?
4. Lot's of things, including AC motors can be made to generate some kind of electricity, but they are often inefficient, or have to be operated at a certain rpm to get much useful out of them. How much output do you want/need? Your answer to that question is going to affect everything in the system from blade size, to how heavy the tower has to be, to how big your battery bank needs to be, times 100 other issues. Analysis of your need really has to come first.
5. The bearing in your average washing machine motor are designed to drive a belt, not support 8' blades. The "prop" will inflict all kinds of loads on those bearings that they were never designed to handle. How many spare motors do you have that are identical, and how often do you want to crawl up there and do a motor transplant? Maybe your transmission will be designed to handle both axial and radial loads typical of a wind turbine. You're an engineer right?
6. Congratulations, you have just installed a really big lightning rod, I mean, Wind turbine tower. Do you know how to keep your house from getting fried with the next thunderstorm?
7. Do you know which kind of charge controller to get that also includes a dump load so your turbine won't overspeed and blow up the next time your battery bank is fully charged? A wind turbine MUST have an electrical load at all times. Sometimes that can't be your battery bank, b/c it's already charged.
8. And 19 other things I'm forgetting at the moment
OK, this is not meant to be critical of the idea. It's meant to illustrate that there are multitude of factors that will determine if you have a successful turbine or not, no matter what the form of the actual generator/alternator is.
So, here's the payoff. There's a bunch of home brew folks who hash this stuff out and teach each other how to get the job done. They are a nice bunch. This is the best discussion group for how to do home brew wind power on the planet, bar none.http://www.otherpower.com/
They sell a nice little book for not too much money to show you the ropes if you want to build their style of machine, which has 99.9% of all the kinks already ironed out.
They also have a discussion group:http://www.fieldlines.com/
There are LOTS of motors and whatnot out there that can be made into wind machines. Every one has some pros and some cons. Go get yourself educated. They'll teach you about towers, magnets, rewiring car alternators, building blades, electrical, electronics, home brew controllers, building one completely from scratch, etc etc etc etc. You have many hours of enjoyable work ahead of you.
I have no relation to them, except as a happy participant and occasional customer.