Old Newbie,
I think it is good to have an idea that you are building for FF. You will learn that you will build it differently if it is strictly for display. I have built and flown these 400 series right out of the box. It was my Mustang that I had my best flight in those early attempts with the the kit prop and rubber. I would leave off the landing gear if you plan to fly Rubber FF.
The important thing is build it straight and balance the model. To do this I put a short rubber motor in the plane to hold the prop. Then go though your test glides. I want my models to glide straight. Start low to the ground...eventually from over your head a nice toss... I would hope for a 10 to 1 glide ratio.
You can look though the forum here and learn how to make the model lighter and better, but I do not want to overwhelm you if you do not have a specific question.
I have made every model in the 400 series (each a few times). The Mustang has been a good flyer for me. I think if you follow the build instructions in the box you should have a nice 10-15 second flight that would stay inside a school yard or small field.
Mitch
PS Here is a picture of the last Mustang I built. I used domestic colored tissue paper. This was built with some contest wood, a removable wing and adjustable nose block, rear peg moved forward, tan rubber and a 9 inch Peck prop. You can build yours right out of the box. This was built for Competition.
