A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

how many pounds thrust needed ?



 
 
Thread Tools Display Modes
  #1  
Old September 11th 03, 05:43 AM
cdubya
external usenet poster
 
Posts: n/a
Default how many pounds thrust needed ?

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

http://www.continuo.com/marske/jar22...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




Ads
  #2  
Old September 11th 03, 05:47 AM
cdubya
external usenet poster
 
Posts: n/a
Default

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




  #3  
Old September 11th 03, 06:20 AM
TomnKeyLargo
external usenet poster
 
Posts: n/a
Default

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
  #4  
Old September 11th 03, 06:27 AM
CH
external usenet poster
 
Posts: n/a
Default

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




  #5  
Old September 11th 03, 06:48 AM
cdubya
external usenet poster
 
Posts: n/a
Default

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




  #6  
Old September 11th 03, 08:26 AM
Alan Baker
external usenet poster
 
Posts: n/a
Default

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."
  #7  
Old September 11th 03, 08:40 AM
CH
external usenet poster
 
Posts: n/a
Default

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."



  #8  
Old September 11th 03, 12:13 PM
Marcel Duenner
external usenet poster
 
Posts: n/a
Default

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/jahres...mertreffen.htm
somewhere in the middle
and
http://home.arcor.de/luftpiraten/luf.../glos_w00.html
under Winggrid
  #9  
Old September 11th 03, 07:03 PM
BD5ER
external usenet poster
 
Posts: n/a
Default


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



  #10  
Old September 13th 03, 10:00 AM
Martin Hellman
external usenet poster
 
Posts: n/a
Default

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
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
more radial fans like fw190? jt Military Aviation 51 August 28th 04 04:22 AM
spaceship one Pianome Home Built 169 June 30th 04 05:47 AM
max altitude and Mach 1 Boomer Military Aviation 22 June 1st 04 08:04 PM
P-38 Exhaust Stephen Harding Military Aviation 10 April 19th 04 07:03 AM
More long-range Spitfires and daylight Bomber Command raids, with added nationalistic abuse (was: #1 Jet of World War II) The Revolution Will Not Be Televised Military Aviation 161 September 25th 03 07:35 AM


All times are GMT +1. The time now is 12:09 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Copyright 2004-2022 AviationBanter.
The comments are property of their posters.