Re: how many pounds thrust needed ?

[cdubya]

About 200 lbs of thrust. Try this link. Read paragraph 4 at bottom of page

http://www.continuo.com/marske/jar22/modifications%20to%20jar%2022%20march%2
024,%202002.htm

Craig





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
>
>

[cdubya]

Guess the link didn't work. Here is the text.

4. Turbine powered self launch gliders: Currently under development is a
simple turbine type engine to be used for self-launching gliders. The size
of a 2 lb coffee can and weighing 16 lbs it can produce enough power to
launch an 800 lb glider. Only 3 moving parts 150 - 200 lbs thrust. Without a
propeller much retraction complexity is eliminated. The high thrust line
associated with a large propeller produces a strong nosedown pitch when
power is applied. Air drag of a stationary or windmilling propeller is
extremely high compared to the small exposed turbine engine. If the engine
does not restart immediately the pilot is in deep trouble due to the high
drag propeller

Craig

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
>
>

[TomnKeyLargo]

The P160 JetCat with 37 lbs of thrust should give you about 400 fpm on a 15
meter ship. We worked the numbers out for a ASW 27 this last spring. It could
self launch with a auto tow to get you up to speed to break ground. 2.5 gals
of fuel will give you about 5 2500 ft. climbs. They have a FCM for engine
start and just need a batery like we carry already. The P160 goes for about
$3995. My R/C friends have smaller versions on their r/c Jets. Try to find a
r/c hobby shop for a field around you where these guys are flying. They are
something to see. Tom

[CH]

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


"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
>
>

[cdubya]

Her is just what you want. I like this idea.

Two J.E.T. Ltd Cobra turbo-jet engines have been
successfully installed in a French built Cri-Cri
aircraft. The Cobra powered plane is the World's
smallest jet .

picture of the craft is at the bottom of the page

http://www.gasturbine.pwp.blueyonder.co.uk/page2.htm




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]

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."

[CH]

Ok Ok ....
I should have left the crazy conversion to non metric units
to blokes with more experience to twist units around

a. horizontal approx. 105 N or 23.6 lb
b. climb approx. 238 N or 53.6 lb

happy now?
Chris


"Alan Baker" > wrote in message
...
> 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."

[Marcel Duenner]

There is a jet-powered sailplane called Prometheus built at the Swiss
Federal Institute of Technology in Zurich sometime in the seventies.
I couldn't find much on it on the web. Only this: Its a side-by-side
double seater with two jet engines with about 900N thrust each gives
the Glider a 6m/s (12kts) climb at 200km/h (108kts).
Seems slightly overpowered to me.

In the meantime they have cut off quite a bit of the wings and are
testing so-called winggrids as an alternative to winglets.

http://www.fva.rwth-aachen.de/jahresschrift/99/sommertreffen.htm
somewhere in the middle
and
http://home.arcor.de/luftpiraten/luftpiraten/glos_w00.html
under Winggrid

[BD5ER]

>
>Her is just what you want. I like this idea.
>
>Two J.E.T. Ltd Cobra turbo-jet engines have been
>successfully installed in a French built Cri-Cri
>aircraft. The Cobra powered plane is the World's
>smallest jet .
>
>picture of the craft is at the bottom of the page
>
>http://www.gasturbine.pwp.blueyonder.co.uk/page2.htm
>
>
>
>
>Jim Culp > wrote in message
...
>>
>> Gentlefolk,
>>
>> Rough estimate please:
Just for the fun of it I took the 19m Cirrus thing that comes with X-plane,
bumped the weight to 1000 take off, and added two 40 lb thrust jet motors at
the cg. The TO performance isn't that great but it will self launch in about
400 feet and fly about 90 knots.

Bumping the thrust to 80 lbs each gets it off the ground - very - well.

X-plane is generally pretty close to reality if you give it good numbers to
work with.
>> 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

[Martin Hellman]

Jim Culp > wrote in message >...
> 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

CH gave formulas that work in a later post in this thread, but there's
a simpler (at least to me) way to calculate these numbers.

a) L/D is the ratio of Lift (which equals glider weight) to Drag. So,
if the ship weighs 705 lb and L/D=30 (as in CH's example), then the
drag is 705/30 = 23.5 lb. You have to use the L/D at the speed you are
operating, so drag will increase at higher speeds, where the L/D drops
off.

b) To get the additional, "climb thrust" needed for a given climb
rate, take the true air speed (60 kts), divide by the climb rate (3
kts) to get 20. Then divide the weight of the glider (705 lbs) by 20
to get the additional thrust needed for this climb rate (35.25 lb).

Add this additional, climb thrust to the level drag to get total
required thrust, 58.75 lb. Note that if the desired climb rate equaled
the true air speed, you would need to add 100% of the glider's weight
to the level drag. Which makes sense. A thrust to weight ratio of a
little more than 1 is needed for vertical flight.

It's interesting that nautical units are better than even metric
(km/hr and m/sec) for calculations like this, at least within 1%.
That's because, within 1% (OK, more like 1.01%) a nautical mile is
6000 feet, a number which is evenly divisible by the number of minutes
in an hour. That's why 300 fpm = 3 kts (within 1%).

Hope someone else finds this simpler too.

Martin

[MB]

Don't forget the Caproni A-21J/A-21SJ. I believe that was the first Jet
sailplane. They addressed the 'melting the tail" problem by splitting
the exhaust into two vectors, each having a slight angle away from the tail.

It was moderately heavy at the time (early 70's I think), ~1400 lbs, w/
220 lbs of thrust, but climbed well, particularly at altitude. Only a
few (+/-3) still registered.


Mike





Martin Hellman wrote:
> Jim Culp > wrote in message >...
>
>>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
>
>
> CH gave formulas that work in a later post in this thread, but there's
> a simpler (at least to me) way to calculate these numbers.
>
> a) L/D is the ratio of Lift (which equals glider weight) to Drag. So,
> if the ship weighs 705 lb and L/D=30 (as in CH's example), then the
> drag is 705/30 = 23.5 lb. You have to use the L/D at the speed you are
> operating, so drag will increase at higher speeds, where the L/D drops
> off.
>
> b) To get the additional, "climb thrust" needed for a given climb
> rate, take the true air speed (60 kts), divide by the climb rate (3
> kts) to get 20. Then divide the weight of the glider (705 lbs) by 20
> to get the additional thrust needed for this climb rate (35.25 lb).
>
> Add this additional, climb thrust to the level drag to get total
> required thrust, 58.75 lb. Note that if the desired climb rate equaled
> the true air speed, you would need to add 100% of the glider's weight
> to the level drag. Which makes sense. A thrust to weight ratio of a
> little more than 1 is needed for vertical flight.
>
> It's interesting that nautical units are better than even metric
> (km/hr and m/sec) for calculations like this, at least within 1%.
> That's because, within 1% (OK, more like 1.01%) a nautical mile is
> 6000 feet, a number which is evenly divisible by the number of minutes
> in an hour. That's why 300 fpm = 3 kts (within 1%).
>
> Hope someone else finds this simpler too.
>
> Martin