In the scene in the desert, after Indy finds the Ark of the Covenant and the Nazis recapture it, what plane is involved in the big fight scene?

A made up one. No such plane existed.

One that was designed to never leave the ground.

It's the plane Al Pachino used in "Heat".  

I thought it was a movie plane.  I couldn't find anything like it in my German aircraft book.

Quoted: A made up one. No such plane existed.

Though it would not be surprising if it had existed on paper.  The Nazis were way ahead of their time on paper.  They had trouble getting new concepts into production but they were never short on new ideas.

Quoted: It's the plane Al Pachino used in "Heat".

Here's a cool site to give you an idea of what I mean:

Luft '46

Quoted: I thought it was a movie plane.  I couldn't find anything like it in my German aircraft book.

The closet thing to it would be a Horton Ho V, but that was a much smaller plane.

They talk about it in the DVD special features which I rented once.  I think I remember hearing it was similar to some prototype of a plane that was never produced.

The German Flying Wing



The plane in Raiders looked so unique because it was.
Here is a quote from
The Raiders of the Lost Ark Collector's Album.

"The futuristic Flying Wing was chosen by director Steven Spielberg to represent the ominous and advanced state of aeronautics in Hitler's Germany Production designer Norman Reynolds used a Northrop Corporation prototype of the Flying Wing and drawings by Ron Cobb to design for Raiders of the Lost Ark this strange plane that has no tail and no fuselage. The plane was built in England by Vickers Aircraft Company and painted at EMI Elstree Studios in London. In order to ship the elaborate prop to Tunisia for filming, it had to be disassembled and sent in parts, then rebuilt on location. In the film the Flying Wing is in Egypt (the Tunisian location) for the top secret mission of transporting the sacred Ark of the Covenant. But before the Ark is even aboard the plane, a series of dramatic events results in the fiery destruction of the Flying Wing."



This plane was never air-worthy,
and has been stowed at the Disney Indiana Jones Attraction.

** LINK **

As other people have mentioned, it's not a real plane, but it was probably inspired by designs like the German Horten brothers and the Northrop N-1M,XB-35, and YB-49.

It's real.  I took a picture of my son standing next to it.  At Disney World.

Well, yes, they actually built it for the movie but it wasn't a "real" aircraft that could actually fly.

Quoted: The German Flying Wing www.indygear.com/props/images/Fwingb.jpg The plane in Raiders looked so unique because it was. www.indygear.com/props/images/Fwing2b.jpg This plane was never air-worthy, and has been stowed at the Disney Indiana Jones Attraction. ** LINK **

Fine Scale Modeler did an article on updating the toy lookalike they sell there.
It turned out pretty cool.