To: Docket No. FAA-2007-27310

Date: July 9, 2007

From: Paul Wilde, Ph.D., P.E.

16826 Middle Forest Drive

Houston, TX 77059

I respectfully submit the following comments as a rocket scientist with
a professional and personal interest in rocket activities. I hope these
help the FAA ensure that amateur rocket activities thrive under safe
conditions.

1.  The preamble (see FR p.32817 last paragraph) states that "the FAA
    protects people and property from the dangers of advanced rocket
    operations by using hazard areas and operating restrictions," yet
    there are no "hazard areas" identified per se by any of the proposed
    regulatory language. The proposed regulation text includes several
    statements to the effect that must not "operate in a manner that
    creates a hazard to persons, property, or other aircraft," which is
    a clear acknowledgement by the FAA that these classes of rockets
    (even model and large model rockets) can be operated in a manner
    that creates a hazard. What are the hazard area requirements the FAA
    proposes to protect people and property from the dangers of amateur
    rocket operations? The proposed regulation does include an implied
    hazard distance of 1500 feet for high power rockets, which I suggest
    be clarified as discussed below.

2.  I recommend that the FAA adopt the NFPA approach in establishing the
    minimum separation between a launch point and spectators (see NFPA
    1127 paragraph 4.16) and other exposed elements of the pubic (see
    1127 paragraph 4.15.3). There is precedent for a regulatory
    authority to promulgate NFPA requirements. The NFPA 1127 is the
    basis for the current best practices that have been successful in
    protecting people from amateur rocket activities to date. NFPA 1127
    includes requirements, including many definitions of key terms,
    which are often necessary for clarity and appropriate for adoption
    by a regulatory authority. An exception is that the FAA should
    clarify that the term "launch" in NFPA 1127 requirements refers to
    the launch point when defining minimum separation distances. An
    excellent approach would be to keep the highly flexible performance
    based requirements proposed (i.e. must not "operate in a manner that
    creates a hazard to persons, property, or other aircraft," eliminate
    the specific distances (i.e. 1500 feet) in the regulation text, add
    that the operator must establish an appropriate hazard area, and
    simultaneously issue an Advisory Circular based on NFPA 1127, state
    in the preamble that compliance with the AC is sufficient to
    demonstrate compliance with the regulation, specifically the hazard
    area requirements. This approach would require reasonable hazard
    areas and enable an applicant to demonstrate compliance by following
    best current practices as stated in the familiar NFPA code for
    rockets up to the O motor level.

3.  The proposed 101.25 states that, "*No person may operate a Class
    3-High Power Rocket-...(d) within 1500 feet of any person or
    property that is not associated with the operations;*" Is this
    intended to ensure at least 1500 feet between the launch point (e.g.
    launch rail location) and members of the public, or does "operate"
    include activation of a recovery system or other phase of flight? A
    definition of operate or some other clarification is recommended.

4.  The preamble (see FR p.32817 last paragraph) states that "a hazard
    area is any region where there is a significant potential for harm
    from the rocket activity. Access to a hazard area is controlled or
    monitored by the operator (or by others through agreements) to
    protect the uninvolved public." Do spectators qualify as the
    uninvolved public? Note that the NFPA High Power Rocket Code (1127)
    includes spectator areas within the "launch site." I recommend that
    the FAA adopt this same approach: prescribe or encourage the minimum
    launch site dimensions in NFPA 1127 Table 4.14.2 to maintain a safe
    separation between these rocket activities and all those that a
    completely uninvolved (i.e. not participants or spectators, etc.).

5.  For amateur rockets with a total impulse above the O motor level, I
    recommend the FAA develop guidance in an Advisory Circular based on
    the "Supplemental Application Guidance for Un-guided Suborbital
    Launch Vehicles."

6.  The preamble (see FR p.32823 third from the last paragraph)
    encourages any applicant proposing to altitude to follow an FAA
    guidance document that includes the following statements.

> "An impact hazard area is defined as two circles and straight lines
> connecting the circles at tangent points to the circles. The first
> circle, with origin at the launch vehicle's launch point, has a radius
> of 1 nautical mile. The second circle, with an origin at the nominal
> no wind impact point of the last launch vehicle stage, has a radius of
> 3 (sigma) of the nominal trajectory as defined in Attachment 1."
>
> I recommend the FAA, at a minimum, clarify if/how this guidance
> applies to High Power rockets since the proposed rule at 101.25(d)
> implies a hazard area of 1500 ft. Should the guidelines hazard area be
> used in lieu of the 1500ft for any such launches planned to reach
> above 25000 ft? How should an applicant establish a hazard area based
> on the guidelines if the rocket is intended to fly straight up? Is the
> 1nm a minimum value for a hazard area to be used even if the nominal
> impact dispersion area is less? When computing the nominal impact
> dispersion area for a multiple stage rocket that includes control
> systems intended to inhibit ignition of the subsequent stages under
> conditions that would lead to excessive dispersion, should the control
> system be assumed to fail?