motorgliders as towplanes

At 12:30 19 March 2009, Bob Cook wrote:

Clearly not a geologist then. I wonder why they do gravity surveys if it
is a constant?

Ok I'll bite.....

Since I am a firm believer that you can't change gravity (although some
of you out there try to in your analysis), gravity remains constant.

Further to earlier post. Gravity is measured in Gals (in honour of
Galileo), 1 Gal = an acceleration of 1 cm/sec2. Average gravity at the
surface is 980.654321 Gals (or so). At the poles it is more at about 983
Gals and on equatorial mountain tops only 977 Gals - a difference of about
0.6%. There are significant local variations. Now if we start to take
height into account...

By the way, what happened to the discussion about slow tows?


At 14:15 19 March 2009, Big Wings wrote:
At 12:30 19 March 2009, Bob Cook wrote:

Clearly not a geologist then. I wonder why they do gravity surveys if
it
is a constant?

Ok I'll bite.....

Since I am a firm believer that you can't change gravity (although
some
of you out there try to in your analysis), gravity remains constant.

On Thu, 19 Mar 2009 17:00:04 +0000, Big Wings wrote:

Further to earlier post. Gravity is measured in Gals (in honour of
Galileo), 1 Gal = an acceleration of 1 cm/sec2. Average gravity at the
surface is 980.654321 Gals (or so). At the poles it is more at about
983 Gals and on equatorial mountain tops only 977 Gals - a difference of
about 0.6%. There are significant local variations. Now if we start to
take height into account...

I notice that's not an SI unit. Is the Gal some sort of engineering or
specialist geological unit? Its a pretty big unit for gravimetry, since
the maximal variation at the earths surface is only 6 Gals.

The SI unit is uM/s^2 (micrometers per sec squared), or 0.1 milliGals,
which looks more in tune with what satellites and aerial surveys are
measuring these days.

By the way, what happened to the discussion about slow tows?

Got too slow and stalled in.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Dear Big,

You are on to something here. Get one of those geo surveys, and fly your
glider only over areas of higher gravity. This extra gravity will give
your glider extra power, and you will be the best glider pilot!

Cookie

At 14:15 19 March 2009, Big Wings wrote:
At 12:30 19 March 2009, Bob Cook wrote:

Clearly not a geologist then. I wonder why they do gravity surveys if
it
is a constant?

Ok I'll bite.....

Since I am a firm believer that you can't change gravity (although
some
of you out there try to in your analysis), gravity remains constant.

At 00:45 20 March 2009, Bob Cook wrote:

You are on to something here. Get one of those geo surveys, and fly
your
glider only over areas of higher gravity. This extra gravity will give
your glider extra power, and you will be the best glider pilot!

Well, that should work. The important thing is that you have to find and
use thermals only in *low* gravity areas, and then do your inter-thermal
cruising in the *high* gravity areas. Next best thing to dynamic
soaring.

Jim Beckman