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Old September 11th 03, 08:26 AM
Alan Baker
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In article ,
"CH" wrote:

Its easy mate
a.
lets assume that your LS4 has 320kg (705lb) mass
and a glide ratio of 30 at 70kt(130km/h, 36m/s)
to fly with this speed you will need
320kg*9.81 / 30 = 105N thrust (72lbf)

b.
at 36m/s horizontal speed and 1/30 the sink speed
results in 1.2m/s.
You wanna climb with 300ft/min (1.524m/s)
to achieve that the engine has to give you 2.7m/s
vertical speed which would make roughly
105/1.2*2.724 = 238.4N thrust (53.6lbf)

CH


Check me on this:

Have you just not shown that climbing requires 20 lb less thrust than
level flight?

Don't you think there's something wrong there?



"Jim Culp" wrote in message
...

Gentlefolk,

Rough estimate please:

How many pounds thrust might be needed
to
keep a std class glider with std pilot aboard
such as a
Std Libelle or Ls4 or Discus

a) continuing in level flight at 60-70 knots
b) climb at rate of 3oo fpm at 60-70 knots

Sure, Ok. You got it.

Thinking one or two Graupner JetCat Gas Turbines
and such, as might be got from Motors & Rotors of Watford,
UK, suitably applied to gliderairframe in extendable/retractable
manner with weight of extension hardware and mountings
and engine and fuel, with maybe 20lbs jet A fuel aboard.


Thus, a Graupner JetCat jet turbine sustainer or climb
propulsion set up, with one or two engines.

Wonder if any of the glider manufacturers or akafliegs
are working on such an application?

If not, why not?
Seems natural.
So much simpler than propeller systems.

These engines are good. I have seen them operate
in Gainesville Florida. Super. Amazing.
Quite powerful and reliable now.
What an advance in 'model' or small turbine engines
they are.

Visioning: Turbine Sustainer or Climber, Enroute Turbine
Power for Glider - Thus, a set of doors above or
below and behind landing gear, you know aft of landing
gear on top or bottom that open and close like gear
doors, being turbine engine doors.

A pop up or down or pop out turbine or two on extension
rack.

Self startable by triggering in cockpit (the Graupner
JetCats do that) .

Vertical fin and empenage covered with heat resistant
foils, tho the distance from turbine blast may obviate
need for this after experiments disprove need for thermal
protex.

Possible need for turbine horizontal or vertical V
nozzles to direct heat blast appropriately.

Right now, there is a model aircraft weighing 133lbs
that does take offs with two of these Graupner JetCat
120s . shown at 'YAS - Yorkshire Air Spectacular
' . See those engines there. These engines are
used widely now, in model jet power and rotorcraft
and they are moving some amazing weights in flight.
Little model aircraft are too too little for these
engines.

These things are real. They move mass. Heavy mass,
and pretty large airframes of many types. Amazing
engineering.

Dancing on clouds,

Keep it up!

Jim Culp USA
GatorCity Florida
Std Libelle





--
Alan Baker
Vancouver, British Columbia
"If you raise the ceiling 4 feet, move the fireplace from that wall
to that wall, you'll still only get the full stereophonic effect
if you sit in the bottom of that cupboard."