Safety of winch launch vrs. aero tow?

In article ,
Bob Johnson wrote:

Our engine is petrol fueled. Despite Google's best efforts, I have not
yet located a Torque/HP/RPM curve for our very common 7.4 L engine, but
have heard that it develops max torque and HP at about 3000 RPM and
further that the curves are fairly flat at this point.

You are making some totally contradictory and inconsistent claims there.

If max torque and max HP occur close together then they must both drop
off precipitously after that.

If the torque curve is flat then HP will be increasing linearly with
RPM, max torque and max HP will be very far apart.


It is quite likely that you do have maximum torque at around 3000 RPM,
but if for example the torque curve is flat enough that the torque at
the 5000 RPM redline is still 60% or more of that at 3000 RPM then that
(redline) is exactly where maximum power will be.

-- Bruce

Hi Bruce --

That's a very welcome correction to my hazily-remembered version of a
second-hand report of what the 454 c.i. engine torque/hp/rpm chart looks
like. This is the kind of info I was looking for and thanks for providing it!

In all our past kicking around of the ideal winch prime mover, here's one
that sounds silly but might rate at least an engineering investigation -- a
recip steam engine! If I recall correctly, the steam engine develops max
torque at stall.

What got me thinking about that was the fact that the Navy gets 66,000 lb
Super Hornets flying in about the same three seconds that it takes us to get
airborne. And they do it with steam, not because it's handy, but that's
probably the only practical way to get it done.

BJ

Bruce Hoult wrote:

In article ,
Bob Johnson wrote:

Our engine is petrol fueled. Despite Google's best efforts, I have not
yet located a Torque/HP/RPM curve for our very common 7.4 L engine, but
have heard that it develops max torque and HP at about 3000 RPM and
further that the curves are fairly flat at this point.

You are making some totally contradictory and inconsistent claims there.

If max torque and max HP occur close together then they must both drop
off precipitously after that.

If the torque curve is flat then HP will be increasing linearly with
RPM, max torque and max HP will be very far apart.

It is quite likely that you do have maximum torque at around 3000 RPM,
but if for example the torque curve is flat enough that the torque at
the 5000 RPM redline is still 60% or more of that at 3000 RPM then that
(redline) is exactly where maximum power will be.

-- Bruce

Actually, I read somewhere that the US Navy is converting its steam
catapults to linear electric motors to get finer control over the launch. I
also suspect that it reduces the manpower required to operate the "cat".

Bill Daniels

"Bob Johnson" wrote in message
...
Hi Bruce --

That's a very welcome correction to my hazily-remembered version of a
second-hand report of what the 454 c.i. engine torque/hp/rpm chart looks
like. This is the kind of info I was looking for and thanks for providing
it!

In all our past kicking around of the ideal winch prime mover, here's one
that sounds silly but might rate at least an engineering investigation --
a
recip steam engine! If I recall correctly, the steam engine develops max
torque at stall.

What got me thinking about that was the fact that the Navy gets 66,000 lb
Super Hornets flying in about the same three seconds that it takes us to
get
airborne. And they do it with steam, not because it's handy, but that's
probably the only practical way to get it done.

BJ

Bruce Hoult wrote:

In article ,
Bob Johnson wrote:

Our engine is petrol fueled. Despite Google's best efforts, I have not
yet located a Torque/HP/RPM curve for our very common 7.4 L engine,
but
have heard that it develops max torque and HP at about 3000 RPM and
further that the curves are fairly flat at this point.

You are making some totally contradictory and inconsistent claims there.

If max torque and max HP occur close together then they must both drop
off precipitously after that.

If the torque curve is flat then HP will be increasing linearly with
RPM, max torque and max HP will be very far apart.

It is quite likely that you do have maximum torque at around 3000 RPM,
but if for example the torque curve is flat enough that the torque at
the 5000 RPM redline is still 60% or more of that at 3000 RPM then that
(redline) is exactly where maximum power will be.

-- Bruce

Gonna take a California Governor-sized battery and alternator combo down there
in the nuclear engine room!

Using my handy-dandy winch horsepower spreadsheet, solving for required
launching force is an incredible 218,000 pounds and over 50,000 horsepower! Of
course the engines are in full AB, but still ---

Other numbers are a "ground run" of 306 ft and a peak acceleration of 3.3G in
2.4 sec.

I can see that they have already provided the Super Hornet with a pretty stout
nosegear. That's where their "cg hook" is, I believe.

BJ

Bill Daniels wrote:

Actually, I read somewhere that the US Navy is converting its steam
catapults to linear electric motors to get finer control over the launch. I
also suspect that it reduces the manpower required to operate the "cat".

Bill Daniels

"Bob Johnson" wrote in message
...
Hi Bruce --

That's a very welcome correction to my hazily-remembered version of a
second-hand report of what the 454 c.i. engine torque/hp/rpm chart looks
like. This is the kind of info I was looking for and thanks for providing
it!

In all our past kicking around of the ideal winch prime mover, here's one
that sounds silly but might rate at least an engineering investigation --
a
recip steam engine! If I recall correctly, the steam engine develops max
torque at stall.

What got me thinking about that was the fact that the Navy gets 66,000 lb
Super Hornets flying in about the same three seconds that it takes us to
get
airborne. And they do it with steam, not because it's handy, but that's
probably the only practical way to get it done.

BJ

Bruce Hoult wrote:

In article ,
Bob Johnson wrote:

Our engine is petrol fueled. Despite Google's best efforts, I have not
yet located a Torque/HP/RPM curve for our very common 7.4 L engine,
but
have heard that it develops max torque and HP at about 3000 RPM and
further that the curves are fairly flat at this point.

You are making some totally contradictory and inconsistent claims there.

If max torque and max HP occur close together then they must both drop
off precipitously after that.

If the torque curve is flat then HP will be increasing linearly with
RPM, max torque and max HP will be very far apart.

It is quite likely that you do have maximum torque at around 3000 RPM,
but if for example the torque curve is flat enough that the torque at
the 5000 RPM redline is still 60% or more of that at 3000 RPM then that
(redline) is exactly where maximum power will be.

-- Bruce

I love it! The boiler could provide the permanent thermal off the top of the
launch too!

Ian

"Bob Johnson" wrote in message
...
Hi Bruce --

That's a very welcome correction to my hazily-remembered version of a
second-hand report of what the 454 c.i. engine torque/hp/rpm chart looks
like. This is the kind of info I was looking for and thanks for providing
it!

In all our past kicking around of the ideal winch prime mover, here's one
that sounds silly but might rate at least an engineering investigation --
a
recip steam engine! If I recall correctly, the steam engine develops max
torque at stall.

What got me thinking about that was the fact that the Navy gets 66,000 lb
Super Hornets flying in about the same three seconds that it takes us to
get
airborne. And they do it with steam, not because it's handy, but that's
probably the only practical way to get it done.

BJ

Bruce Hoult wrote:

In article ,
Bob Johnson wrote:

Our engine is petrol fueled. Despite Google's best efforts, I have not
yet located a Torque/HP/RPM curve for our very common 7.4 L engine,
but
have heard that it develops max torque and HP at about 3000 RPM and
further that the curves are fairly flat at this point.

You are making some totally contradictory and inconsistent claims there.

If max torque and max HP occur close together then they must both drop
off precipitously after that.

If the torque curve is flat then HP will be increasing linearly with
RPM, max torque and max HP will be very far apart.

It is quite likely that you do have maximum torque at around 3000 RPM,
but if for example the torque curve is flat enough that the torque at
the 5000 RPM redline is still 60% or more of that at 3000 RPM then that
(redline) is exactly where maximum power will be.

-- Bruce

In article ,
Bob Johnson wrote:

In all our past kicking around of the ideal winch prime mover, here's one
that sounds silly but might rate at least an engineering investigation -- a
recip steam engine! If I recall correctly, the steam engine develops max
torque at stall.

That is true, and it is also true of many electric motors.

Unfortunately, I suspect that if they are strong enough with the glider
flying at 60 knots then they will be far *too* strong at the start!

-- Bruce

I believe a German club has recently built themselves a DC winch using
dozens of automotive type batteries. Haven't heard how they have done
with it, though.

BJ

Bruce Hoult wrote:

In article ,
Bob Johnson wrote:

In all our past kicking around of the ideal winch prime mover, here's one
that sounds silly but might rate at least an engineering investigation -- a
recip steam engine! If I recall correctly, the steam engine develops max
torque at stall.

That is true, and it is also true of many electric motors.

Unfortunately, I suspect that if they are strong enough with the glider
flying at 60 knots then they will be far *too* strong at the start!

-- Bruce

There once was a non-BGA soaring site/club in East Anglia in the UK. The
operator was named Fred, but the surname escapes me and I believe he passed
away in the 1980's. By all accounts he operated a steam winch though I
never met him nor saw it in action. I believe that operation was dwindling
and may have ceased operations about 1980. Any stories out there?

Frank Whiteley

"Bob Johnson" wrote in message
...
Hi Bruce --

That's a very welcome correction to my hazily-remembered version of a
second-hand report of what the 454 c.i. engine torque/hp/rpm chart looks
like. This is the kind of info I was looking for and thanks for providing
it!

In all our past kicking around of the ideal winch prime mover, here's one
that sounds silly but might rate at least an engineering investigation --
a
recip steam engine! If I recall correctly, the steam engine develops max
torque at stall.

What got me thinking about that was the fact that the Navy gets 66,000 lb
Super Hornets flying in about the same three seconds that it takes us to
get
airborne. And they do it with steam, not because it's handy, but that's
probably the only practical way to get it done.

BJ

Bruce Hoult wrote:

In article ,
Bob Johnson wrote:

Our engine is petrol fueled. Despite Google's best efforts, I have not
yet located a Torque/HP/RPM curve for our very common 7.4 L engine,
but
have heard that it develops max torque and HP at about 3000 RPM and
further that the curves are fairly flat at this point.

You are making some totally contradictory and inconsistent claims there.

If max torque and max HP occur close together then they must both drop
off precipitously after that.

If the torque curve is flat then HP will be increasing linearly with
RPM, max torque and max HP will be very far apart.

It is quite likely that you do have maximum torque at around 3000 RPM,
but if for example the torque curve is flat enough that the torque at
the 5000 RPM redline is still 60% or more of that at 3000 RPM then that
(redline) is exactly where maximum power will be.

-- Bruce

In article , F.L. Whiteley
writes
There once was a non-BGA soaring site/club in East Anglia in the UK. The
operator was named Fred, but the surname escapes me and I believe he passed
away in the 1980's. By all accounts he operated a steam winch though I
never met him nor saw it in action. I believe that operation was dwindling
and may have ceased operations about 1980. Any stories out there?

Frank Whiteley

In the 60s there was an instructor at the Midland GC who had the idea of
building a steam winch.

Because the Long Mynd is largely peat, we thought we might use the
terrain as a fuel source.

The project never got off the ground; we never got any steam driven,
Mynd fuelled launches.


--
Mike Lindsay
n