Jet Sailplane Flies!

All,
Please refer to the following link to see a video of the Silent moter-glider
with jet engine's attached. It is absolutely amazing watching a sailplane
doing a low pass with jet engines screaming, AND self-launching.
http://www.alisport.com/pag_ing/news.htm

Yes, the Jet's on the Silent ARE retractable.

For those of you who saw the pictures of the Ventus 2 moter-glider with Jet
engines attached, there is no way that thing self-launched. It does not count
unless it can self-launch! Here are the general numbers for those of you who
would like to do the math. The engines produce 34 pounds of thrust each, and
with a flying weight of about 1000 pounds, initial takeoff acceleration would
be a blistering 0.06 G's (About 1 knot a second). You would need a REALLY long
runway (See Edwards AFB) at sea level in order to get the thing in the air, IF
they could even produce enough thrust to beat the breaking point to start the
roll (Doubtful).
-Mitch Hudson

(Mhudson126) wrote in message
All,
Please refer to the following link to see a video of the Silent moter-glider
with jet engine's attached. It is absolutely amazing watching a sailplane
doing a low pass with jet engines screaming, AND self-launching.

(snippage)

Jet Engines Screaming? So much for the "Silent" part of that self
launcher. The one that started of with the electric motor, didn't it?
Ah, progress. Time to get back to work on that pulse jet for the HP.

Steve Leonard

(Mhudson126) wrote in message ...
All,
Please refer to the following link to see a video of the Silent moter-glider
with jet engine's attached. It is absolutely amazing watching a sailplane
doing a low pass with jet engines screaming, AND self-launching.
http://www.alisport.com/pag_ing/news.htm

Yes, the Jet's on the Silent ARE retractable.

For those of you who saw the pictures of the Ventus 2 moter-glider with Jet
engines attached, there is no way that thing self-launched. It does not count
unless it can self-launch! Here are the general numbers for those of you who
would like to do the math. The engines produce 34 pounds of thrust each, and
with a flying weight of about 1000 pounds, initial takeoff acceleration would
be a blistering 0.06 G's (About 1 knot a second). You would need a REALLY long
runway (See Edwards AFB) at sea level in order to get the thing in the air, IF
they could even produce enough thrust to beat the breaking point to start the
roll (Doubtful).
-Mitch Hudson



Don't try this site with Netscape 7.1 but it works ok with IE 5.5.

Andy

It's a great sight and a great achievement. Practically though these
engines have a huge problem of poor fuel consumption. The consumption is
about 95lts/hour. A petrol self launcher will use 16lts/hr and will have a
21lt tank. To give the same duration the jet will need a very large and
heavy-when-full 120lt tank.

"Mhudson126" wrote in message
...
All,
Please refer to the following link to see a video of the Silent
moter-glider
with jet engine's attached. It is absolutely amazing watching a sailplane
doing a low pass with jet engines screaming, AND self-launching.
http://www.alisport.com/pag_ing/news.htm

Yes, the Jet's on the Silent ARE retractable.

For those of you who saw the pictures of the Ventus 2 moter-glider with
Jet
engines attached, there is no way that thing self-launched. It does not
count
unless it can self-launch! Here are the general numbers for those of you
who
would like to do the math. The engines produce 34 pounds of thrust each,
and
with a flying weight of about 1000 pounds, initial takeoff acceleration
would
be a blistering 0.06 G's (About 1 knot a second). You would need a REALLY
long
runway (See Edwards AFB) at sea level in order to get the thing in the
air, IF
they could even produce enough thrust to beat the breaking point to start
the
roll (Doubtful).
-Mitch
Hudson

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

Not for me (too noisy) but interesting.

I wouldn't want all that heat pointed at my vertical stabilizer though.
Also, I imagine you'd have to let it cool down before retracting the
engines.

Paul Remde


"Mhudson126" wrote in message
...
All,
Please refer to the following link to see a video of the Silent
moter-glider
with jet engine's attached. It is absolutely amazing watching a sailplane
doing a low pass with jet engines screaming, AND self-launching.
http://www.alisport.com/pag_ing/news.htm

Yes, the Jet's on the Silent ARE retractable.

For those of you who saw the pictures of the Ventus 2 moter-glider with
Jet
engines attached, there is no way that thing self-launched. It does not
count
unless it can self-launch! Here are the general numbers for those of you
who
would like to do the math. The engines produce 34 pounds of thrust each,
and
with a flying weight of about 1000 pounds, initial takeoff acceleration
would
be a blistering 0.06 G's (About 1 knot a second). You would need a REALLY
long
runway (See Edwards AFB) at sea level in order to get the thing in the
air, IF
they could even produce enough thrust to beat the breaking point to start
the
roll (Doubtful).
-Mitch
Hudson

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