HTHL vs VTVL - Thunderbirds to the rescue

First, I am a VTVL fan first but that does not mean you should not think of
other possible solutions.

While thinking about the problem of the weight of take-off and landing gear I
remembered an episode of ThunderBirds where they used a sled to save a SST
landing that could not lower it's landing gear.

While a number of people have suggested using a rocket sled for takeoff to
remove the need for the heavy gear of takeoff what about using a braking sled
for landing. A HTHL that has no T/L gear has just made a major wieght
savings.

Valid idea, or fool's dream?

Earl Colby Pottinger
--
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Earl Colby Pottinger wrote in message
...
First, I am a VTVL fan first but that does not mean you should not think
of
other possible solutions.

While thinking about the problem of the weight of take-off and landing
gear I
remembered an episode of ThunderBirds where they used a sled to save a SST
landing that could not lower it's landing gear.

While a number of people have suggested using a rocket sled for takeoff to
remove the need for the heavy gear of takeoff what about using a braking
sled
for landing. A HTHL that has no T/L gear has just made a major wieght
savings.

Valid idea, or fool's dream?

The difficulties of hitting the sled precisely (getting it accelerated to
match your vehicle's speed, etc.), plus reliability issues, and the "what do
you do if you have to land somewhere else" question kinda make it a no-go.

Earl Colby Pottinger wrote in message
...
First, I am a VTVL fan first but that does not mean you should not think
of
other possible solutions.

While thinking about the problem of the weight of take-off and landing
gear I
remembered an episode of ThunderBirds where they used a sled to save a SST
landing that could not lower it's landing gear.

While a number of people have suggested using a rocket sled for takeoff to
remove the need for the heavy gear of takeoff what about using a braking
sled
for landing. A HTHL that has no T/L gear has just made a major wieght
savings.

Valid idea, or fool's dream?

The difficulties of hitting the sled precisely (getting it accelerated to
match your vehicle's speed, etc.), plus reliability issues, and the "what do
you do if you have to land somewhere else" question kinda make it a no-go.

Earl Colby Pottinger wrote:

First, I am a VTVL fan first but that does not mean you should not think of
other possible solutions.

While thinking about the problem of the weight of take-off and landing gear I
remembered an episode of ThunderBirds where they used a sled to save a SST
landing that could not lower it's landing gear.

While a number of people have suggested using a rocket sled for takeoff to
remove the need for the heavy gear of takeoff what about using a braking sled
for landing. A HTHL that has no T/L gear has just made a major wieght
savings.

Valid idea, or fool's dream?

Earl Colby Pottinger

Certainly not impossible, but launching *from* a ground accelerator
(Fireball XL-5, anyone?) is rather different from matching velocities
with, and landing *on* such a device. Espically when there's finite
runway or track on which to do it, and assorted wether variables that
wouln't affect a launch as much.

I know the episode you refer to, and by definition, it was an
emergency situation, not something you'd want as part of regular
operations....


--

You know what to remove, to reply....

Earl Colby Pottinger wrote:

First, I am a VTVL fan first but that does not mean you should not think of
other possible solutions.

While thinking about the problem of the weight of take-off and landing gear I
remembered an episode of ThunderBirds where they used a sled to save a SST
landing that could not lower it's landing gear.

While a number of people have suggested using a rocket sled for takeoff to
remove the need for the heavy gear of takeoff what about using a braking sled
for landing. A HTHL that has no T/L gear has just made a major wieght
savings.

Valid idea, or fool's dream?

Earl Colby Pottinger

Certainly not impossible, but launching *from* a ground accelerator
(Fireball XL-5, anyone?) is rather different from matching velocities
with, and landing *on* such a device. Espically when there's finite
runway or track on which to do it, and assorted wether variables that
wouln't affect a launch as much.

I know the episode you refer to, and by definition, it was an
emergency situation, not something you'd want as part of regular
operations....


--

You know what to remove, to reply....

On Dec 9, 2003, at 1:39 PM, Bob Martin wrote:

The difficulties of hitting the sled precisely (getting it accelerated
to
match your vehicle's speed, etc.), plus reliability issues, and the
"what do
you do if you have to land somewhere else" question kinda make it a
no-go.

Make the Sled do the work?
It's not starved for fuel, and it could use that to match velocities
with the ship.
The ship lowers itself, the sled latches on, and begins braking.

Granted, the margins are gonna be PRETTY THIN if the ship is an
Unpowered Glider.

Aloha mai Nai`a!
--
"Please have your Internet License http://kapu.net/~mjwise/
and Usenet Registration handy..."

On Dec 9, 2003, at 1:39 PM, Bob Martin wrote:

The difficulties of hitting the sled precisely (getting it accelerated
to
match your vehicle's speed, etc.), plus reliability issues, and the
"what do
you do if you have to land somewhere else" question kinda make it a
no-go.

Make the Sled do the work?
It's not starved for fuel, and it could use that to match velocities
with the ship.
The ship lowers itself, the sled latches on, and begins braking.

Granted, the margins are gonna be PRETTY THIN if the ship is an
Unpowered Glider.

Aloha mai Nai`a!
--
"Please have your Internet License http://kapu.net/~mjwise/
and Usenet Registration handy..."

Earl Colby Pottinger wrote in message ...
First, I am a VTVL fan first but that does not mean you should not think of
other possible solutions.

While thinking about the problem of the weight of take-off and landing gear I
remembered an episode of ThunderBirds where they used a sled to save a SST
landing that could not lower it's landing gear.

While a number of people have suggested using a rocket sled for takeoff to
remove the need for the heavy gear of takeoff what about using a braking sled
for landing. A HTHL that has no T/L gear has just made a major wieght
savings.

Valid idea, or fool's dream?

Earl Colby Pottinger

Your idea has merrit since new electronic control and location methods
should allow relatively accurate manoevering for 'mating' of an
aricraft and sled.

Control systems to auotmatically land and 'capture' helicopter on an
rolling miitary ship exist. (this is a version of the above
situation) as well as auomtaitc arrested landings on aircraft
carriers.


Since the mass fraction of a hypothetical single stage to orbit
vehicle is around 10:1 most of the gains in undercarriage weight are
in saving on mass in the launch weight since only a smaller
undercarriage is required for landing. I believe undercarriage mass
is usually around 4% though the B58 Hustler managed 1.6% somehow.

Much of the undecarriage weight is infact brake. The brake is
required to deccelerate an aircraft during an aborted takeoff. Allan
Bonds Skylon space plane used water to cool the brakes and dumped the
water immediatly upon liftoff. This substantialy reduced the brake and
therefore undercarriage weight.

Earl Colby Pottinger wrote in message ...
First, I am a VTVL fan first but that does not mean you should not think of
other possible solutions.

While thinking about the problem of the weight of take-off and landing gear I
remembered an episode of ThunderBirds where they used a sled to save a SST
landing that could not lower it's landing gear.

While a number of people have suggested using a rocket sled for takeoff to
remove the need for the heavy gear of takeoff what about using a braking sled
for landing. A HTHL that has no T/L gear has just made a major wieght
savings.

Valid idea, or fool's dream?

Earl Colby Pottinger

Your idea has merrit since new electronic control and location methods
should allow relatively accurate manoevering for 'mating' of an
aricraft and sled.

Control systems to auotmatically land and 'capture' helicopter on an
rolling miitary ship exist. (this is a version of the above
situation) as well as auomtaitc arrested landings on aircraft
carriers.


Since the mass fraction of a hypothetical single stage to orbit
vehicle is around 10:1 most of the gains in undercarriage weight are
in saving on mass in the launch weight since only a smaller
undercarriage is required for landing. I believe undercarriage mass
is usually around 4% though the B58 Hustler managed 1.6% somehow.

Much of the undecarriage weight is infact brake. The brake is
required to deccelerate an aircraft during an aborted takeoff. Allan
Bonds Skylon space plane used water to cool the brakes and dumped the
water immediatly upon liftoff. This substantialy reduced the brake and
therefore undercarriage weight.

In article , The
Enlightenment wrote:

Control systems to auotmatically land and 'capture' helicopter on an
rolling miitary ship exist. (this is a version of the above
situation) as well as auomtaitc arrested landings on aircraft
carriers.

As I understand it, the situation with helicopter landings is that the
helicopter lands on the deck, and then is latched onto - it doesn't
"land on" the locking device, but the locking device gets it once it's
down. Very quickly once it's down, mind you, but...

(I can check this with Them As Knows More About It, when I next see him,
but I do know there's two commonly used systems - I may only have
understood one)

--
-Andrew Gray