How to paint a perfect stripe on a nose?

Mount the prop on a shaft and chuck it in a Dremel.  Adjust so it spins true without nay wobble.  At a fairly low speed touch a brush loaded with paint and the stripe will be perfect.

I use Tamiya tape with success.

I have an old piece of glass (from a cheap photo frame) that i stick a lenth of tape too.  Then i use a metal ruler and a brand new No.11 blade to cut a lenght of tape to the desired width.  I read about this method on another website years ago (I think it was Swanny's tips on how to mask canopies or something similar). 

Using this method enables you to cut tape to any desired width and the glass backing enables the blade to cut through easily and also, the tape to lift up without losing too much adhesion.

Also, DoogsATX is quite right with having momentum when taping.  Whenever i'm taping, i hold the end of the tape and look to where it should finish, pull it taught and then lay it down.  Following this, i then burnish down.

However, it will be a bit mor tedious and difficult with a conical surface like the prop of the Mustang, but it can still be down, just requires patience and practice.

Chris.

ditto to the fineline tape.

Fineline can be tough to track down, though. If you're impatient, you can get this stuff at your local Hobby Lobby, and it works quite well:

http://shop.hobbylobby.com/products/fa2038-artist-tape-for-curves-133546/

I've used it to mask several cowl and fuselage bands:

The key, I've found, is to use momentum taping...get a good run more or less positioned, THEN burnish it down. If you burnish a bit at a time, the tape is flexible enough that you'll end up with a janky line.

Thank you very much for your reply. The images were there when posted and now seem to be not viewable. I will definitely give that a try. Thanks again!!

By the way the model I am working on is Bud Anderson's "Old Crow".

I can't see your images, but PTFE tape (like plumbers use), or automotive self adhesive fineline tape are both pretty good for doing what I think you want. Failing that, Tamiya tape cut very thin (a few mm) goes where you want it & conforms reasonably well.

I would be tempted to try 3mm fineline tape, 3M do "471 fineline tape" which is generally available through automotive refinishing suppliers, but there are quite a few different manufacturers out there.