Jet Sailplane Flies!

To give the same duration the jet will need a very large and
heavy-when-full 120lt tank.

Yes but what about the weight saving over the mechanics of the petrol
engine/prop etc.?

Peter S
DLA

The advantage of the lightweight jet engine is totally eclipsed by the fuel
consumption problem.

A self launcher engine and prop and fuel tanks weighs 55-60kg with full fuel
tanks. They are already heavy enough and it would be better to go lighter
not heavier.

A pair of jet engines will weigh only 7kg but the fuel with tanks will be
about 95kg and so at 103kg is nearly double the weight surcharge,
furthermore as I implied before there is a big problem in finding enough
room to store 120lts. There may also be a weight and balance issue but if
the fuel were stored in the wing tanks instead of water ballast that would
be less of a problem but you would have little room left or weight reserve
for water then. You could treat the fuel as ballast and dump the fuel if
you chose to, it is pretty cheap stuff, cheaper than many brands of mineral
water.

If there existed a model fanjet engine and if it were to use say less than
half the fuel, a jet engine would begin to look like a good option.

"Peter Seddon" wrote in message
...
To give the same duration the jet will need a very large and
heavy-when-full 120lt tank.

Yes but what about the weight saving over the mechanics of the petrol
engine/prop etc.?

Peter S
DLA

http://www.popsci.com/popsci/aviatio...563899,00.html

Interesting reading in the 01/2004 Popular Science and the approach to fuel
consumption.

Frank Whiteley

"John Mason" wrote in message
...
The advantage of the lightweight jet engine is totally eclipsed by the
fuel
consumption problem.

A self launcher engine and prop and fuel tanks weighs 55-60kg with full
fuel
tanks. They are already heavy enough and it would be better to go lighter
not heavier.

A pair of jet engines will weigh only 7kg but the fuel with tanks will be
about 95kg and so at 103kg is nearly double the weight surcharge,
furthermore as I implied before there is a big problem in finding enough
room to store 120lts. There may also be a weight and balance issue but if
the fuel were stored in the wing tanks instead of water ballast that would
be less of a problem but you would have little room left or weight reserve
for water then. You could treat the fuel as ballast and dump the fuel if
you chose to, it is pretty cheap stuff, cheaper than many brands of
mineral
water.

If there existed a model fanjet engine and if it were to use say less than
half the fuel, a jet engine would begin to look like a good option.

"Peter Seddon" wrote in message
...
To give the same duration the jet will need a very large and
heavy-when-full 120lt tank.

Yes but what about the weight saving over the mechanics of the petrol
engine/prop etc.?

Peter S
DLA

If there existed a model fanjet engine and if it were to use say less
than
half the fuel, a jet engine would begin to look like a good option.

Not so long ago a jet engine of the size to fit into a model was just a
dream so perhaps a small turbo fan my soon be on the cards.

Peter S
DLA

If the goal is soaring, whta is such amount of fuel needeed?

Fuel for few minutes to climb up to 500-1000 m, then fly soaring with only a
little amount of spare fuel to lenghten the final glide, if seems to be
getting short and no chance of convections. Maybe that 55-60 kg total weight
would be enough for engine and fuel, about half of it as emergency spare.

Noisy yes, and qoite flammable with burning heat gases.

There is a rocket fuel, peroxid, which generates adjustable thrust and
exhausts only hot water and oxygen, but it's unfortunately dangerosly
bioactive. Used to blond hair, too.

js


"John Mason" wrote in message
...
The advantage of the lightweight jet engine is totally eclipsed by the
fuel
consumption problem.

A self launcher engine and prop and fuel tanks weighs 55-60kg with full
fuel
tanks. They are already heavy enough and it would be better to go lighter
not heavier.

A pair of jet engines will weigh only 7kg but the fuel with tanks will be
about 95kg and so at 103kg is nearly double the weight surcharge,
furthermore as I implied before there is a big problem in finding enough
room to store 120lts. There may also be a weight and balance issue but if
the fuel were stored in the wing tanks instead of water ballast that would
be less of a problem but you would have little room left or weight reserve
for water then. You could treat the fuel as ballast and dump the fuel if
you chose to, it is pretty cheap stuff, cheaper than many brands of
mineral
water.

If there existed a model fanjet engine and if it were to use say less than
half the fuel, a jet engine would begin to look like a good option.

"Peter Seddon" wrote in message
...
To give the same duration the jet will need a very large and
heavy-when-full 120lt tank.

Yes but what about the weight saving over the mechanics of the petrol
engine/prop etc.?

Peter S
DLA