HTHL vs VTVL - Wheeled sled for landing?

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Earl Colby Pottinger - 13 Dec 2003 01:27 GMT

Thinking about the problem some more it seems a big problem would be landing
a high speed glider onto a sled that is on tracks. This would mean that the
sled could only control it's movements in one dimension. A bad cross wind or
gust leaves the glider to do all the working of correction with it's limited
energy budget. If instead the sled is a wheeled platform then it can follow
the glider's movements instead.

Any comments? Maybe HTHL is possible with today's tech!

Earl Colby Pottinger

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Len - 15 Dec 2003 15:01 GMT

> Thinking about the problem some more it seems a big problem would be landing
> a high speed glider onto a sled that is on tracks. This would mean that the
[quoted text clipped - 6 lines]
>
> Earl Colby Pottinger

A WWII CVL carrier was, IIRC, only about 67 ft wide. I found
that lining up with a carrier with a narrow beam could be more
of a challenge than catching one of 11 wires between the stern
and the barrier--at the relatively low landing speed of a
Hellcat.

Our current (unpublished) X PRIZE concept is a high mass ratio
vehicle. Takeoff is from a dolly and landing is on skids with
a nose wheel. The effective penalty for "landing gear" can be
quite reasonable with this technique. The X-15 used air launch,
skids and nose wheel to good effect--even with a more modest
mass ratio.

Best regards,
Len (Cormier)
PanAero, Inc.
len@tour2space.com ( http://www.tour2space.com )

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Oren Tirosh - 24 Dec 2003 16:10 GMT

> Thinking about the problem some more it seems a big problem would be landing
> a high speed glider onto a sled that is on tracks. This would mean that the
> sled could only control it's movements in one dimension. A bad cross wind or
> gust leaves the glider to do all the working of correction with it's limited
> energy budget. If instead the sled is a wheeled platform then it can follow
> the glider's movements instead.

Why wheels? Use a hovercraft as your sled.

Designed to operate in a place like salt flats, Utah, it may bear more
resemblance to an industrial hover-skate for heavy loads than to a
hovercraft in the english channel. It can match the returning
vehicle's velocity on two dimensions and absorb much of the vertical
velocity using a cradle cushioned with large, leaky, air bags inflated
by the same fans that generate lift.

The same hovercraft can be used for takeoff (possibly with a different
cradle configuration and boosters). There is no need for special
runways or reinforced pavement. With an air cushion and plenty of room
to accelerate (and decelerate) it can reach very high speeds and
reduce the size and weight of the wings.

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Earl Colby Pottinger - 25 Dec 2003 05:04 GMT

oren@REMOVETHIS1.hishome.net.retro.com (Oren Tirosh) :

> Why wheels? Use a hovercraft as your sled.

Well developed tech. Easy to get up to speed. Easy to design brakes for.
Braking a hovercraft is going to be a pain.

> Designed to operate in a place like salt flats, Utah, it may bear more
> resemblance to an industrial hover-skate for heavy loads than to a
> hovercraft in the english channel. It can match the returning
> vehicle's velocity on two dimensions and absorb much of the vertical
> velocity using a cradle cushioned with large, leaky, air bags inflated
> by the same fans that generate lift.

Yes about the landing bags, I was starting to think of that too. Made of a
higher temperature material like fiberglass the landing craft does not even
need to be completely cooled down before landing.

> The same hovercraft can be used for takeoff (possibly with a different
> cradle configuration and boosters). There is no need for special
> runways or reinforced pavement. With an air cushion and plenty of room
> to accelerate (and decelerate) it can reach very high speeds and
> reduce the size and weight of the wings.

The same applies for a wheeled design. Still nothing is carved in stone here.

Earl Colby Pottinger

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Space Forum / Space Flight / December 2003

HTHL vs VTVL - Wheeled sled for landing?