HTHL vs VTVL - Wheeled sled for landing?

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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Earl Colby Pottinger wrote in message ...
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

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Our current (unpublished) X PRIZE concept is a high mass ratio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.
( http://www.tour2space.com )

Earl Colby Pottinger wrote in message ...
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

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.
( http://www.tour2space.com )

Charles Buckley wrote in message ...
Earl Colby Pottinger wrote:
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



If I am understanding this correctly, you have a seld on the
ground that the descending vehicle connects to as part of the landing,
correct?

In that case, you need to factor in how to cause the coupling between
the vehicle and the sled. Would you accelerate the sled up to speed,
or would you do a zero-velocity capture? Or something else?

Len mentioned the alignment issue. I will address the zero-velocity
capture. In that, you need some sort of arresting gear that would
be able to handle the velocity differential and it's resultant shear
on the arresting gear. I suspect that a detailed calculation between
the weight and requirements of an arresting gear vs a skid on the
vehicle actually favors a skid mount on the vehicle itself. That
lateral shear is much less on something designed to apply the
deceleration slowly.

I favor either a skid or wheeled landing for a HL independant of
any ground mechanism. The way to improve glader landing characteristics
is to maximize L/D and reduce ground speed, then stick with landing
zones that have multiple vectored approaches to allow for better
crosswind options.

If the returning vehicle is light enough and slow enough,
then I think that air recovery--perhaps with a helicopter
--is more practical than trying to line up with a sled on
the ground. As a pilot, I am much happier with a couple
of minutes, rather than ten seconds, to match speeds and line
up with the recovery vehicle.

Relative speeds are far more important than absolute speeds.
However, this seems to scare non-pilot types a bit. Military
pilots learn to fly in tight formation at high subsonic speeds
and in almost any attitude. It's fun.

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

Charles Buckley wrote in message ...
Earl Colby Pottinger wrote:
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



If I am understanding this correctly, you have a seld on the
ground that the descending vehicle connects to as part of the landing,
correct?

In that case, you need to factor in how to cause the coupling between
the vehicle and the sled. Would you accelerate the sled up to speed,
or would you do a zero-velocity capture? Or something else?

Len mentioned the alignment issue. I will address the zero-velocity
capture. In that, you need some sort of arresting gear that would
be able to handle the velocity differential and it's resultant shear
on the arresting gear. I suspect that a detailed calculation between
the weight and requirements of an arresting gear vs a skid on the
vehicle actually favors a skid mount on the vehicle itself. That
lateral shear is much less on something designed to apply the
deceleration slowly.

I favor either a skid or wheeled landing for a HL independant of
any ground mechanism. The way to improve glader landing characteristics
is to maximize L/D and reduce ground speed, then stick with landing
zones that have multiple vectored approaches to allow for better
crosswind options.

If the returning vehicle is light enough and slow enough,
then I think that air recovery--perhaps with a helicopter
--is more practical than trying to line up with a sled on
the ground. As a pilot, I am much happier with a couple
of minutes, rather than ten seconds, to match speeds and line
up with the recovery vehicle.

Relative speeds are far more important than absolute speeds.
However, this seems to scare non-pilot types a bit. Military
pilots learn to fly in tight formation at high subsonic speeds
and in almost any attitude. It's fun.

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

Charles Buckley :

If I am understanding this correctly, you have a seld on the
ground that the descending vehicle connects to as part of the landing,
correct?

First, it a wheeled sled that is also used for launching the HTHL. This
means it is powered and is capable of matching the landing speed of the HTHL
craft.

In that case, you need to factor in how to cause the coupling between
the vehicle and the sled. Would you accelerate the sled up to speed,
or would you do a zero-velocity capture? Or something else?

Anything short of matched speeds sounds too dangerous to me. Yes, it would
run at the same ground speed of the landing craft.

Len mentioned the alignment issue.

Since it is wheeled, not on tracks it can align itself to the ground track of
the landing craft.

I will address the zero-velocity
capture. In that, you need some sort of arresting gear that would
be able to handle the velocity differential and it's resultant shear
on the arresting gear. I suspect that a detailed calculation between
the weight and requirements of an arresting gear vs a skid on the
vehicle actually favors a skid mount on the vehicle itself. That
lateral shear is much less on something designed to apply the
deceleration slowly.

That is why zero velocity was not even considered by me.

I favor either a skid or wheeled landing for a HL independant of
any ground mechanism.

But that is extra weight on the landing craft that is not needed.

The way to improve glader landing characteristics
is to maximize L/D and reduce ground speed, then stick with landing
zones that have multiple vectored approaches to allow for better
crosswind options.

None of those considerations prevent the use of a land based powered landing
sled that matchs speed and ground track with the landing craft (note I don't
assume it is without any power) thus saving more weight.

Note: the feedback system to make the sled track the landing craft can be as
simple as a laser directed downwards from the base of the landing craft and a
set of sensors on the sled insure that the beam is always held in the center
of the landing sled's platform.

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

Charles Buckley :

If I am understanding this correctly, you have a seld on the
ground that the descending vehicle connects to as part of the landing,
correct?

First, it a wheeled sled that is also used for launching the HTHL. This
means it is powered and is capable of matching the landing speed of the HTHL
craft.

In that case, you need to factor in how to cause the coupling between
the vehicle and the sled. Would you accelerate the sled up to speed,
or would you do a zero-velocity capture? Or something else?

Anything short of matched speeds sounds too dangerous to me. Yes, it would
run at the same ground speed of the landing craft.

Len mentioned the alignment issue.

Since it is wheeled, not on tracks it can align itself to the ground track of
the landing craft.

I will address the zero-velocity
capture. In that, you need some sort of arresting gear that would
be able to handle the velocity differential and it's resultant shear
on the arresting gear. I suspect that a detailed calculation between
the weight and requirements of an arresting gear vs a skid on the
vehicle actually favors a skid mount on the vehicle itself. That
lateral shear is much less on something designed to apply the
deceleration slowly.

That is why zero velocity was not even considered by me.

I favor either a skid or wheeled landing for a HL independant of
any ground mechanism.

But that is extra weight on the landing craft that is not needed.

The way to improve glader landing characteristics
is to maximize L/D and reduce ground speed, then stick with landing
zones that have multiple vectored approaches to allow for better
crosswind options.

None of those considerations prevent the use of a land based powered landing
sled that matchs speed and ground track with the landing craft (note I don't
assume it is without any power) thus saving more weight.

Note: the feedback system to make the sled track the landing craft can be as
simple as a laser directed downwards from the base of the landing craft and a
set of sensors on the sled insure that the beam is always held in the center
of the landing sled's platform.

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

Earl Colby Pottinger wrote in message ...
(Len) :

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.

Still what was your relative speed to the carrier? I am talking about
landing on a platform that matchs your ground speed on purpose. IE if you
are landing at 100 KPH that is the also the speed of the platform. Also it
uses feedback so if you drift from side to side it matchs your movements
automaticly.

The carrier might have about 30 knots wind over the deck (WOD).
I was still a bachelor and used to fly an approach at about
67 knots (between the power-on and power-off stall speeds--OK
so Navy pilots are all crazy, especially when they are still
teenagers). That would give only about 37 knots relative speed
in the intended direction of landing. However, side motions
might be quite signifcant. I'm afraid they often were in my
case.

So while you do need to line up to the landing platform in the final stages
of landing it appears to move very slowly in ralationship to the landing
craft.

I think that the main problem is the lack of time to get
everything going at the same speed and direction. That's
why I like a long glide to rendezvous; it could give the
pilot and the recovery aircraft a lot more time to get
into the right position, altitude and speed.

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.

How big and fast can skids go? Is water cooling possible with them? I
really don't know. Can something the size/weight of the shuttle be landed
this way?

With wire brush skids, I suspect that they could be a lot
better than tires with respect both to landing speed and
reentry temperatures.

Best regards,
Len (Cormier)
PanAero, Inc.
(replace x with len) ( http://www.tou2space.com )

Earl Colby Pottinger

Earl Colby Pottinger wrote in message ...
(Len) :

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.

Still what was your relative speed to the carrier? I am talking about
landing on a platform that matchs your ground speed on purpose. IE if you
are landing at 100 KPH that is the also the speed of the platform. Also it
uses feedback so if you drift from side to side it matchs your movements
automaticly.

The carrier might have about 30 knots wind over the deck (WOD).
I was still a bachelor and used to fly an approach at about
67 knots (between the power-on and power-off stall speeds--OK
so Navy pilots are all crazy, especially when they are still
teenagers). That would give only about 37 knots relative speed
in the intended direction of landing. However, side motions
might be quite signifcant. I'm afraid they often were in my
case.

So while you do need to line up to the landing platform in the final stages
of landing it appears to move very slowly in ralationship to the landing
craft.

I think that the main problem is the lack of time to get
everything going at the same speed and direction. That's
why I like a long glide to rendezvous; it could give the
pilot and the recovery aircraft a lot more time to get
into the right position, altitude and speed.

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.

How big and fast can skids go? Is water cooling possible with them? I
really don't know. Can something the size/weight of the shuttle be landed
this way?

With wire brush skids, I suspect that they could be a lot
better than tires with respect both to landing speed and
reentry temperatures.

Best regards,
Len (Cormier)
PanAero, Inc.
(replace x with len) ( http://www.tou2space.com )

Earl Colby Pottinger

Please remember that I am a VTVL fan, I am just trying to give HTHL a fair
shake but getting rid off completely the major weight problem VTVL fans claim
for HTHL.

(Len) :

If the returning vehicle is light enough and slow enough,
then I think that air recovery--perhaps with a helicopter
--is more practical than trying to line up with a sled on
the ground. As a pilot, I am much happier with a couple
of minutes, rather than ten seconds, to match speeds and line
up with the recovery vehicle.

A flying sled? Interesting idea, why not? Now you have the sink time to try
to mate up. You would have time to either do it very slowly or multiple
tries - probably both. Not there is no need for the flysled to be able to
hold the HL up, the HL already has wings, some extra thrust from the flying
sled after mating will keep the air speed up so it can continue to support
itself.

Does light weight really matter? If the catcher aircraft has beefed landing
gear/brakes/support structures to handle the weight of the HL craft then all
the catcher has to do match speeds with the HL, mate, and if needed supply
some thrust to get the HL to the runway. Think off a souped up SS1 but with
the thrusters on the bottom.

Another interesting thing about this idea is the weight of the catcher does
not have to be that high and thus not too expensive.

Relative speeds are far more important than absolute speeds.
However, this seems to scare non-pilot types a bit. Military
pilots learn to fly in tight formation at high subsonic speeds
and in almost any attitude. It's fun.

While not a pilot, I thought this would be well understood. But for some
strange reason more than one person seems to think that I don't plan to have
the landing sled pre-match the landing craft speed first before they meet
which as far as I can see would be a crazy way to land on any sort of movable
pad.

In the case of a flying sled can they be brought together without the airflow
between the two crafts messing up the fine control needed?

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp