On 23 Jun 2004 21:23:16 GMT, (Steve VanSickle)
wrote:

From article , by Richard Lamb Steve VanSickle wrote:

Because it was designed to be a sub-orbital ship...

This particular *design* won't work, yes, but why not the "method" (i.e.
moving surfaces to make for a "hands off" reentry)?

if they can stand up to 3000 degree heat...

Reentry from orbit is a vastly more difficult proposition.

All to the speeds involved.

Yes, it is more difficult. Yes, much hotter, much more energy. But I
have heard many people claim that the "shuttlecock" method Burt developed
"won't work" from orbit, and no one says *why*. If shuttle wings can be
protected (most of the time) from the heat, why can't Burt's wings?

First off, I should point out that in ~25 years in the space biz, I've only
worked *one* program where safe re-entering the atmosphere was a design
element. And I solved THAT by saying, "...assuming it survives re-entry,
we'll deploy the rotors at Mach 3..." :-)

With that out of the way, let me set up some reasons why the shuttlecock
system may not be the best solution for an orbital mission. Feel free to
whack 'em down.

First, you've got a device that must be in the deployed position during
re-entry. Whatever actuators you've got holding the tail in position are
in danger of exposure to the re-entry plasma. On the Shuttle, everything
gets set into positions that minimizes disturbance of the plasma, but the
shuttlecock mode is exactly the opposite.

Two things can happen: The actuators can jam, or the actuators can break.
If they jam, you're not going to land. If they break, your speed increases
and your structure will probably overheat. If one side breaks and one side
jams, you are probably going to end up in a fairly fierce spin.

Yes, you can design covers for the actuators. But the covers themselves
could jam, and cause the same problems they're designed to prevent.

It's not much of a risk during SpaceShipOne's re-entry at Mach 3...the
interface period is over pretty quickly. But OrbitOne will spend about
10-15 minutes in the plasma. A lot of ugly things could happen.

Second...and, probably more-easily overcome...there's the G-load issue.
IIRC, Melville experienced about 5 Gs, maximum, during re-entry. 5 Gs from
a re-entry speed of Mach 3 vs. a re-entry speed of Mach 25. Hmmmm...think
we'll have to trim the size of shuttlecock tail. :-)

Finally, we get to the heretical part of this posting: Why wings at all,
for an orbital mission?

Forty years ago, a few square feet of ablative heat shield was good enough
to handle most manned space missions. The Russian space program has flown
them continuously.

Just because you want to re-use an orbital vehicle doesn't mean it has to
have wings. Unless the vehicle is able to reposition itself from its
landing location to launch location, you're still stuck with considerable
infrastructure to recover, service, and transport the vehicle. Wings on
your deorbit vehicle don't help those functions. They allow pin-point
precision landings...but if you're just going to land out in the desert,
does it really make a difference? If you're aloft for more than one orbit,
you are not going to be able to land at your departure point until about 12
hours later.

For the most part, American capsule landings were within sight of the
recovery base. Isn't that accuracy enough?

However, wings may well have some good application to an orbital vehicle:
They can be used to change orbit planes by aeromaneuvering. That means you
dip into the atmosphere deeply enough to get some 'bite,' then deflect your
orbit aerodynamically. You'll need thrust to bring your perigee back up,
but that's a heck of a lot less than all but the most minor orbital plane
changes. So Burt might keep the wings for OrbitOne.

To me, Rutan's shuttlecock mode is an outstanding engineering solution to
ANOTHER re-entry problem....one which he might re-think, by the time he
gets to the problems of an orbital vehicle.

The Shuttlecock wasn't the only solution to the stable-reentry problem. A
split-flap system would have worked just as well, and would not have
required as wide a movement range.

But...a split-flap system would have imposed the G-loads on the occupants
in the eyeballs-out mode! In other words, the nose of the craft would be
pointing down, and the pilot would have been hanging on his straps during
5G acceleration.

Instead, in the shuttlecock mode, the nose of the vehicle is high, with the
G-loads being supported by the pilot's seat. Great solution to two
problems...

It remains to be seen whether the increased complexity of a similar system
designed for orbital re-entry will overcome the simplicity of a basic heat
shield.

By the way, NASA has "Astronauts," Russia has "Cosmonauts." We need a name
for the ordinary folks who fly on SpaceShipOne:

I hereby suggest "Commonauts" for those lucky SOBs who get to ride Burt's
space bird.

Ron Wanttaja