On Wed, 9 Jul 2003 00:08:14 GMT, (Henry Spencer)
wrote:

In article ,
John Ordover wrote:

The time it takes to go from one airport to another is the least part
of the time it takes Fedex to deliver a package.

FedEx and similar companies have made considerable efforts to minimize the
ground overhead, with some success. That said, it remains significant,
and suborbital package delivery would be interesting mostly for the real
long-haul runs, mostly intercontinental. The advantage there is more than
just the travel time, incidentally, because the short transit times can
avoid timezone problems (e.g. airport-operations curfews) which constrain
current subsonic-aircraft operations.

Having anxiously tracked many FedEx packages, I have to say that
getting the package down the gravel roads in Northeast Iowa in winter
or through Customs any time swamps the time on the airplane.
Particularly the latter.

For the intercontinental runs, suborbital flight does gain enough time to
be really interesting. BUT...

+ Vehicle costs have to be low enough to afford a substantial fleet. You
cannot build a package-delivery service on one or two vehicles.

You will have to have a substantial fleet of ground vehicles, too, and
an efficient ground operation.

+ They pretty much have to be cleared to operate out of major airports,
and in several countries too, with airliner-class paperwork.

Not just out of major airports, but also _into_.

+ Their dispatch reliability -- readiness to fly when scheduled to --
must approach 100%. (Spare vehicles and rapid cargo handling can
cope with some shortfall -- subsonic-aircraft dispatch reliability is
usually below 99% -- but there are practical limits.)

It's not just dispatch reliability but post-takeoff, pre-landing
reliability. It's rare that a FedEx or UPS airplane or truck has an
accident in transit, and if it happened often customers wouldn't use
their services. It doesn't take many "Destroyed in transit" notices
before folks stop shipping irreplaceable objects.

+ They must be capable of flying through any weather except the rarest
and most severe adverse conditions.

It might be easier to do this than it is with aircraft, because it
won't be necessary to forecast the weather at the destination so far
ahead, as is the case for slower aircraft.

+ The vehicle/cargo loss rate must approach 0% very closely.

Both in the air and on the ground. This means safety, security, and
reliability.

(The last three are tied to a fundamental constraint of fast package
delivery: the probability of getting a package there *when promised* has
to be something like 99.999% for the business to be viable.)

Part of the promise is that the package must get there when promised
in good condition. Getting a few scorched shreds there doesn't count.

The chances that these constraints can be satisfied by a first-generation
reusable rocket are nearly zero. A second-generation system... perhaps.

I agree, entirely. However, reusability probably isn't the primary
issue in success or failure.

Mary

--
Mary Shafer Retired aerospace research engineer

"Turn to kill, not to engage." LCDR Willie Driscoll, USN