What is required by the FAA to obtain an experimental type certificate for a manned prototype aircraft?
Found it. It's easy to get lost in the FAR's, but in case you're curious I managed to find the requirements I was looking for under 14 CFR 21.193:
An applicant for an experimental certificate must submit the following information:
(a) A statement, in a form and manner prescribed by the FAA setting forth the purpose for which the aircraft is to be used.
(b) Enough data (such as photographs) to identify the aircraft.
(c) Upon inspection of the aircraft, any pertinent information found necessary by the FAA to safeguard the general public.
(d) In the case of an aircraft to be used for experimental purposes—
(1) The purpose of the experiment;
(2) The estimated time or number of flights required for the experiment;
(3) The areas over which the experiment will be conducted; and
(4) Except for aircraft converted from a previously certificated type without appreciable change in the external configuration, three-view drawings or three-view dimensioned photographs of the aircraft.
(e) In the case of a light-sport aircraft assembled from a kit to be certificated in accordance with §21.191(i)(2), an applicant must provide the following:
(1) Evidence that an aircraft of the same make and model was manufactured and assembled by the aircraft kit manufacturer and issued a special airworthiness certificate in the light-sport category.
(2) The aircraft's operating instructions.
(3) The aircraft's maintenance and inspection procedures.
(4) The manufacturer's statement of compliance for the aircraft kit used in the aircraft assembly that meets §21.190(c), except that instead of meeting §21.190(c)(7), the statement must identify assembly instructions for the aircraft that meet an applicable consensus standard.
(5) The aircraft's flight training supplement.
(6) In addition to paragraphs (e)(1) through (e)(5) of this section, for an aircraft kit manufactured outside of the United States, evidence that the aircraft kit was manufactured in a country with which the United States has a Bilateral Airworthiness Agreement concerning airplanes or a Bilateral Aviation Safety Agreement with associated Implementation Procedures for Airworthiness concerning airplanes, or an equivalent airworthiness agreement.
[Doc. No. 5085, 29 FR 14569, Oct. 24, 1964, as amended by Amdt. 21-85, 69 FR 44862, July 27, 2004]