By: MiG-23MLD
- 25th June 2008 at 02:23Permalink- Edited 1st January 1970 at 01:00
I tried it in easy words.
You claim things, that none did post in that way.
The claim about the wider cross section is from yourself.
Your way to explain, where the higher internal fuel load of the F-111 comes from.
In the meanwhile you have learned, that a lot of fuel is housed in the wings of the F-111, when not so in the Su-24.
The F-111 undercarriage is different to the Su-24, which does free further volume for internal fuel.
The links about the pics were related to that. See the height difference of related cockpits to bottom
All that has nothing to do with logic, but to stick to data and material at hand.
The force to propel the F-111/Su-24 does come from the airflow of the engine.
The TF30 has an airflow of 118 kg/sec each
The AL-21F has an airflow of 105 kg/sec each
To generate that the TF30 has ~5500 kp dry each
To generate that the AF-21F has ~8000 kp dry each
To generate flying thrust you are in need of three main elements.
The most import one is the inlet-system, the second important one is the out-let-system and then the engine. The higher the speed the more in that ranking. At a given speed you do not need even an engine, see the RAM-Jet-system.
The kp output-value has something to do with the temperature. But with a TF you have a bypath-ratio. A hot stream through the engine and a colder one around that, both do produce thrust up to the transonic range.
To have some way to compare effective thrust-levels, you can no longer look at the installed max dry at ground-level and zero-speed.
Comparing Tj or comparing Tf with the same bypath ratio, such comparison can work, but it does not work, when comparing a Tj with a Tf.
I hope you got it, but I fear too much details from my side again for easy understanding.
The higher installed nominal thrust does not mean, that you have the higher force from that too. kN - kg/sec you remember.
The AL-21F has a higher fuel consumption of 10% at least for every kN.
To reach similar flight-performances to a more powerful TF30 the AL-21F is in need of more kN to feed. = double penalty, which does rise the difference to ~30% really.
When you give the F-111 and the Su-24 the same internal fuel of 4 tons for example, what result in range will you get from that.
Will it be none as you claim, or will it be ~10% more for the F-111 or will it be ~30% more for the F-111?
So now we have the mistery thrust, the mystery thrust!:eek: Sens is the TF-30 a ramjet? ramjets only work at speeds of Mach 3 or more, the F-111 is no more than a Mach 2.5 speed aircraft, its inlet only reduces the amount of fuel needed but still it has a specific thrust, using a fan the turbofan reduces the amount of fuel spent, but still a turbofan can not work beyond a specific subsonic flow, besides big turbofans with high by pass ratios are for subsonic speeds and commercial aircraft and beyond that ramjets and turbofans with very low by pass ratios are more practical, these low by pass ratios are not very different from a turbojet in reality. So the AL-21 will spend more fuel to produce the same thrust because it sucks less air, however its thrust is higher at military power, the TF-30 is a low by pass ratio engine not a high by pass ratio like a Trent 900
This Trent 900 high by pass turbofan has a simple inlet nacelle cowling with no ramp or even VG ramp
So Sens this explains you why the TF-30 is not more different than the AL-21 at full afterburner, simply because the by pass ratio is still low.
When you fly at speeds beyond Mach 3 the ramjet can start working.
Now you have to see a reality, the TF-30 has lower yield and has to power a heavier aircraft, but of course you are in one way belittling the Al-21F3 used by the Su-24, this engine might be more fuel thirsty in SFC and this is not by 10% but only 8% at full military power, this engine however will power a lighter aircraft and has a higher thrust at military power.
Sukhoi claims the MTOW for the Su-24MK is slightly more than 43000kg and the RAAF claims the F-111 has a MTWO of almost 52000kg, see that the difference in absolute ferry range at max fuel weight, has a difference in fuel weight of almost 11000kg between both aircraft, that ratio is almost the same in range and in max fuel capacity
By: franc
- 25th June 2008 at 05:36Permalink- Edited 1st January 1970 at 01:00
The size of Tu-22 almost same as B-1, so it is hard to say, Tu-22 is a sort of bomber which is more efficient than neither F-111 or Su-24.
The undercarriger was designed on F-111 makes inlet shorter so that structual weight reduced. Dual-wheel which Su-24 undercarriage used gives a using flexible for wild runway but more space in aeroframe occupied.
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By: MiG-23MLD
- 25th June 2008 at 16:48Permalink- Edited 1st January 1970 at 01:00
The size of Tu-22 almost same as B-1, so it is hard to say, Tu-22 is a sort of bomber which is more efficient than neither F-111 or Su-24.
The undercarriger was designed on F-111 makes inlet shorter so that structual weight reduced. Dual-wheel which Su-24 undercarriage used gives a using flexible for wild runway but more space in aeroframe occupied.
The Tu-22M is in a total different class from the F-111, however the irony is the FB-111 tried to fill the same niche successfully, but it failed and today the Tu-22M remains one of the most sucessful bombers of all time.
The F-111 might have a SFC more economical but at lower thrust.
By: Sens
- 25th June 2008 at 17:06Permalink- Edited 1st January 1970 at 01:00
So now we have the mistery thrust, the mystery thrust!:eek: Sens is the TF-30 a ramjet? ramjets only work at speeds of Mach 3 or more, the F-111 is no more than a Mach 2.5 speed aircraft, its inlet only reduces the amount of fuel needed but still it has a specific thrust, using a fan the turbofan reduces the amount of fuel spent, but still a turbofan can not work beyond a specific subsonic flow, besides big turbofans with high by pass ratios are for subsonic speeds and commercial aircraft and beyond that ramjets and turbofans with very low by pass ratios are more practical, these low by pass ratios are not very different from a turbojet in reality. So the AL-21 will spend more fuel to produce the same thrust because it sucks less air, however its thrust is higher at military power, the TF-30 is a low by pass ratio engine not a high by pass ratio like a Trent 900
This Trent 900 high by pass turbofan has a simple inlet nacelle cowling with no ramp or even VG ramp
So Sens this explains you why the TF-30 is not more different than the AL-21 at full afterburner, simply because the by pass ratio is still low.
When you fly at speeds beyond Mach 3 the ramjet can start working.
Now you have to see a reality, the TF-30 has lower yield and has to power a heavier aircraft, but of course you are in one way belittling the Al-21F3 used by the Su-24, this engine might be more fuel thirsty in SFC and this is not by 10% but only 8% at full military power, this engine however will power a lighter aircraft and has a higher thrust at military power.
Sukhoi claims the MTOW for the Su-24MK is slightly more than 43000kg and the RAAF claims the F-111 has a MTWO of almost 52000kg, see that the difference in absolute ferry range at max fuel weight, has a difference in fuel weight of almost 11000kg between both aircraft, that ratio is almost the same in range and in max fuel capacity
When someone is unable or at best unwilling to understand some basic, there is no problem to accept that. But it becomes worse, when someone tries to distract from that shortcomings through further ridiculous claims.
For the benefit of the others.
The flow of air does behave different with different speeds.
There is the true subsonic range below Mach 0,7 - the transonic range - the true supersonic range and the high supersonic range.
For take-off and climb most aircraft do operate in the true subsonic range, when for cruise they stay in the lower transonic-range at around Mach 0,8.
The best suited engine is the high bypass TF with 4:1 up to 10+:1 or the TP
of 100:1 sticking to the true subsonic range only.
Military TFs are at 1,5:1 or lower, related to the wider speed range.
Military Tj are at best at true supersonic or behind Mach 1,2. The best possible military engine will one with a variable cycle. That was the promise with the first GE F120 engine, which was too futuristic for the USAF.
The low by-path PW F119 does offer the best available compromise between lower fuel consumption of a TF and still good enough at supersonic.
The best compromise for fighters was 0,5:1 in the 80s or lower. Below of 0,5:1 such engines are called "leaky Tj".
Possible through the gains in pressure-ratio and TET.
But for someone I have to push the basics to the limits, despite little hope about that.
The V10 engine of a F1 Ferrari did deliver 925 hp at 19.800 U/min.
The V12 engine of a T-72 MBT did deliver 780 hp at ~2000 U/min.
Nominal the Ferrari engine has a higher output in hp, but none will get the idea to put that into the T-72 MBT?!
Can it be, that hp or kp are not the single yardstick about force?!
The bypath-ratio of the TF30 did differ between 1,1:1 to 17,1 pressure ratio or 0,7:1 to 22 pressure ratio.
Every variant of that was on the higher side of bypath-ratio for military engines (up to 1,5:1)
I never got the idea, that someone may try to compare that to present airliner-engines and their limited flying envelope to operate.
To save my time, I will not explain how an AB does work. (As the related AB-ratios and the related sfc) That does not make sense about the lack of understanding about the basics and the limited use in striker-missions.
Even the math is limited. Please try it again.
0,69 = 100
0,76 = X
The next fancy "highlight" is about MTOW.
The ferry-range is related to the amount of fuel at take-off, whatever you prefer, be it kg or liter. (conversion-rate is ~0,77 kg per liter).
The yardstick is, how far can you go in km for every kg or liter?!
Filling the same amount of fuel into into a Su-24 and the F-111 does bring a remarkable difference in range from that, well behind the difference in SFC.
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By: MiG-23MLD
- 25th June 2008 at 17:37Permalink- Edited 1st January 1970 at 01:00
When someone is unable or at best unwilling to understand some basic, there is no problem to accept that. But it becomes worse, when someone tries to distract from that shortcomings through further ridiculous claims.
For the benefit of the others.
The flow of air does behave different with different speeds.
There is the true subsonic range below Mach 0,7 - the transonic range - the true supersonic range and the high supersonic range.
For take-off and climb most aircraft do operate in the true subsonic range, when for cruise they stay in the lower transonic-range at around Mach 0,8.
The best suited engine is the high bypass TF with 4:1 up to 10+:1 or the TP
of 100:1 sticking to the true subsonic range only.
Military TFs are at 1,5:1 or lower, related to the wider speed range.
Military Tj are at best at true supersonic or behind Mach 1,2. The best possible military engine will one with a variable cycle. That was the promise with the first GE F120 engine, which was too futuristic for the USAF.
The low by-path PW F119 does offer the best available compromise between lower fuel consumption of a TF and still good enough at supersonic.
The best compromise for fighters was 0,5:1 in the 80s or lower. Below of 0,5:1 such engines are called "leaky Tj".
Possible through the gains in pressure-ratio and TET.
But for someone I have to push the basics to the limits, despite little hope about that.
The V10 engine of a F1 Ferrari did deliver 925 hp at 19.800 U/min.
The V12 engine of a T-72 MBT did deliver 780 hp at ~2000 U/min.
Nominal the Ferrari engine has a higher output in hp, but none will get the idea to put that into the T-72 MBT?!
Can it be, that hp or kp are not the single yardstick about force?!
The bypath-ratio of the TF30 did differ between 1,1:1 to 17,1 pressure ratio or 0,7:1 to 22 pressure ratio.
Every variant of that was on the higher side of bypath-ratio for military engines (up to 1,5:1)
I never got the idea, that someone may try to compare that to present airliner-engines and their limited flying envelope to operate.
To save my time, I will not explain how an AB does work. (As the related AB-ratios and the related sfc) That does not make sense about the lack of understanding about the basics and the limited use in striker-missions.
Even the math is limited. Please try it again.
0,69 = 100
0,76 = X
The next fancy "highlight" is about MTOW.
The ferry-range is related to the amount of fuel at take-off, whatever you prefer, be it kg or liter. (conversion-rate is ~0,77 kg per liter).
The yardstick is, how far can you go in km for every kg or liter?!
Filling the same amount of fuel into into a Su-24 and the F-111 does bring a remarkable difference in range from that, well behind the difference in SFC.
Why you forget simple details you that always claim to know details?
You clearly know by simple physics an aircraft needs a force to achieve a speed when it weighs a specific mass and in an aircraft you have to consider gravity and air drag. you know perfectly the F-111 at full military power has a lower Thrust to weight ratio than the Su-24 at full military power, perhaps at subsonic cruise speeds the F-111 is more economical but carrying a heavy load it won`t fly too fast either due to weight
The inlet was designed to disaccelerate the supersonic flow to subsonic speeds, a true ramjet has not such limitations since already air preasure and compression is achieved by the speed the airplane flies, so no need for compressor or blades, however the turbofan and you know it very well can not work with a supersonic flow, it compresses the air but not due to speed since the ramp and duct slow down the supersonic flow to subsonic speeds, and for such a reason you have a ramp or even an variable geometry ramp that generates multishock waves.
A scram jet even can work at supersonic speeds of air flow.
With engines like the TF-30 and AL-21, you have a very similar yield of 11000kg thrust, however one engine compresses air more and needs therefore less fuel to produce thrust however it has lower thrust at military power ask your self at the same max military thrust of the TF-30 the AL-21 does not have its max military power and does not spend the same amount of fuel at a SFC of 0.86, but has a lower fuel consumption .
In a high by pass engine like the Trent 900 you do not need a ramp simply because air is not traveling supersonic so there is no need for a ramp to slow down the supersonic flow however with the olympus fitted to the Concord you need a ramp and the same happens with the F-101 that powers the B-1A and B-1B
By: Sens
- 25th June 2008 at 18:55Permalink- Edited 1st January 1970 at 01:00
Why you forget simple details you that always claim to know details?
You clearly know by simple physics an aircraft needs a force to achieve a speed when it weights a specific mass and in an aircraft you have to consider gravity and air drag. you know perfectly the F-111 at full military power has a lower Thrust to weight ratio than the Su-24 at full military power, perhaps at subsonic cruise speeds the F-111 is more economical but carrying a heavy load it won`t fly to fast either due to weight
The inlet was designed to disaccelerate the supersonic flow to subsonic speeds, a true ramjet has not such limitations since already air preasure and compression is achieved by the speed the airplane flies, so no need for compressor or blades, however the turbofan and you know it very well can not work with a supersonic flow, it compresses the air but not due to speed since the ramp and duct slow down the supersonic flow to subsonic speeds, and for such a reason you have a ramp or even an variable geometry ramp that generates multishock waves.
With engines like the TF-30 and AL-21, you have a very similar yield of 11000kg thrust, however one engine compresses air more and needs therefore less fuel to produce thrust however it has lower thrust at military power ask your self at the same max military thrust of the TF-30 the AL-21 does not have its max military power and does not spend the same amount of fuel at a SFC of 0.76, but has a lower fuel consumption .
In a high by pass engine like the Trent 900 you do not need a ramp simply because air is not traveling supersonic so there is no need for a ramp to slow down the supersonic flow however with the olympus fitted to the Concord you need a ramp and the same happens with the F-101 that powers the B-1A and B-1B
Please read carefully and do sleep a night about that.
Even the simple math you left aside.
The engine has nothing to do with the weight of a flying aircraft at first.
The counterforce of weight is the lift.
That lift is generated by lifting areas and speed. (The single exception are VTOL aircraft).
The more weight you will bring into the air the more lift you are in need of.
A Su-24 or F-111 are in need of lifting areas to do so and some related controls for stability.
But that lift is not for free. In a similar way you rise lift by that, you have to counter the related rise in drag, when doing so.
To counter that drag, you are in need of a propulsion-system. One central part of that is the engine to accelerate to lift-off speed and overcome the flying drag.
The trick is to get the most lift for the least drag. (One of the main advantages of the VG-design).
When doing so you do reduce the need of thrust to overcome the related drag.
Related to your minimum demand in lift you will choose the least draggy speed to do so, which is subsonic in general. The best engine for that is an engine, which does operate close to its optimum cycle, when doing so.
A TF has two cycles to benefit from, when the Tj has a single cycle, which can not adjusted in a similar way to the related power-demands.
In the meanwhile it is common knowledge, that the drag-thrust ratio is the most important yardstick. For the lack of published data about that, some got the idea to use the installed thrust to have a rough yardstick.
When assuming, that in the 50s all jets did have a similar drag, a similar jet-engine, that may have worked some way, just to give the public an idea about that.
That was never true as it its with different designs and technology.
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By: MiG-23MLD
- 26th June 2008 at 01:06Permalink- Edited 1st January 1970 at 01:00
Please read carefully and do sleep a night about that.
Even the simple math you left aside.
The engine has nothing to do with the weight of a flying aircraft at first.
The counterforce of weight is the lift.
That lift is generated by lifting areas and speed. (The single exception are VTOL aircraft).
The more weight you will bring into the air the more lift you are in need of.
A Su-24 or F-111 are in need of lifting areas to do so and some related controls for stability.
But that lift is not for free. In a similar way you rise lift by that, you have to counter the related rise in drag, when doing so.
To counter that drag, you are in need of a propulsion-system. One central part of that is the engine to accelerate to lift-off speed and overcome the flying drag.
The trick is to get the most lift for the least drag. (One of the main advantages of the VG-design).
When doing so you do reduce the need of thrust to overcome the related drag.
Related to your minimum demand in lift you will choose the least draggy speed to do so, which is subsonic in general. The best engine for that is an engine, which does operate close to its optimum cycle, when doing so.
A TF has two cycles to benefit from, when the Tj has a single cycle, which can not adjusted in a similar way to the related power-demands.
In the meanwhile it is common knowledge, that the drag-thrust ratio is the most important yardstick. For the lack of published data about that, some got the idea to use the installed thrust to have a rough yardstick.
When assuming, that in the 50s all jets did have a similar drag, a similar jet-engine, that may have worked some way, just to give the public an idea about that.
That was never true as it its with different designs and technology.
You theory is only part true and over simplistic, why? let us start by simple physics
The newton (symbol: N) is the SI unit of force. It is named after Sir Isaac Newton in recognition of his work on classical mechanics.A newton is the amount of force required to accelerate a mass of one kilogram at a rate of one meter per second squared. In addition http://www.convertworld.com/en/weight/Kilonewton.html
A jet engine measures thrust in Kilo newtons, the Russians usually do it, SFC only reflects the amount of fuel to accelerate kilo newtons.
In a jet engine, air is compressed by a turbine. Fuel is added to this air and is exhausted out the other end. This gas exerts an equal reaction force, providing forward thrust as it exits the engine. This thrust is transmitted from the engine to an airframe and engine mountings to propel the aircraft. Thrust is measured in pounds (lb), kilogram force (kgf), or the international unit, newtons (N).
Fc = mv2/r, where Fc = centrifugal force, m = mass, v = speed, and r = radius
and we can say that despite for us the F-111 or Su-24 are flying straight, in reality they are traveling in a gravitational parabolic path in the same way a cannon ball flies however they constantly burn fuel and fly straight in our reference point of view
parabolic trajectory. The downward force of gravity would act upon the cannonball to cause the same vertical motion as before - a downward acceleration.
now since we are not in the vaccum the F-111 and Su-24 will experience drag, however by simple physics we know An object in motion would continue in motion at a constant speed in the same direction if there is no unbalanced force so our F-111 or Su-24 will slow down due to air drag or in other words friction.
Know if the Su-24 and F-111 have different masses, the same amount of kilo newton force will accelerate them differently since they have a difference in weight.
If the Max military power of the TF-30 is lower then the SFC of the AL-21 at the same thrust will be lower and therefore more efficient than you really expect, now if the Su-24 is lighter and has higher thrust to weight ratio at full military power you can not expect the aircraft to be less fuel efficient as you claim, however in aboslute numbers the F-111 has a longer range and higher payload, in that sense the F-111 is a more efficient aircraft by packing a higher density at a given volume
Now the SRAAM AIM-132 shows you an AAM can fly by just thrust alone
By: Rocky
- 26th June 2008 at 08:25Permalink- Edited 1st January 1970 at 01:00
You theory is only part true and over simplistic, why? let us start by simple physics
The newton (symbol: N) is the SI unit of force. It is named after Sir Isaac Newton in recognition of his work on classical mechanics.A newton is the amount of force required to accelerate a mass of one kilogram at a rate of one meter per second squared. In addition
A jet engine measures thrust in Kilo newtons, the Russians usually do it, SFC only reflects the amount of fuel to accelerate kilo newtons.
In a jet engine, air is compressed by a turbine. Fuel is added to this air and is exhausted out the other end. This gas exerts an equal reaction force, providing forward thrust as it exits the engine. This thrust is transmitted from the engine to an airframe and engine mountings to propel the aircraft. Thrust is measured in pounds (lb), kilogram force (kgf), or the international unit, newtons (N).
Now an aircraft fights gravity by two simple forces, centrifugal force and lift
Fc = mv2/r, where Fc = centrifugal force, m = mass, v = speed, and r = radius
and we can say that despite for us the F-111 or Su-24 are flying straight, in reality they are traveling in a gravitational parabolic path in the same way a cannon ball flies
No no no. A jet is rarely in ballistic flight, and never in cruise.
however they constantly burn fuel and fly straight in our reference point of view
parabolic trajectory. The downward force of gravity would act upon the cannonball to cause the same vertical motion as before - a downward acceleration.
now since we are not in the vaccum the F-111 and Su-24 will experience drag, however by simple physics we know An object in motion would continue in motion at a constant speed in the same direction if there is no unbalanced force so our F-111 or Su-24 will slow down due to air drag or in other words friction.
Know if the Su-24 and F-111 have different masses, the same amount of kilo newton force will accelerate them differently since they have a difference in weight.
If the Max military power of the TF-30 is lower then the SFC of the AL-21 at the same thrust will be lower and therefore more efficient than you really expect, now if the Su-24 is lighter and has higher thrust to weight ratio at full military power you can not expect the aircraft to be less fuel efficient as you claim, however in aboslute numbers the F-111 has a longer range and higher payload, in that sense the F-111 is a more efficient aircraft by packing a higher density at a given volume
:rolleyes:
This is a mass of irrelevancy. Thrust to weight ratio and acceleration have nothing to do with range or fuel consumption in cruise. A jet is not an ICBM. Sens knows more about the issues here than I do, so I'm not going to wade into this fencing match, but you are clearly lost in the dark.
Now the SRAAM AIM-132 shows you an AAM can fly by just thrust alone
No, it gets lift from its body. But I very much doubt it reaches any equilibrium between thrust and drag before burnout, so it doesn't cruise either.
The Saturn V also is wingless and flies
The Saturn V does not fly. A glider flies. A Saturn V is ballistic.
By: Sens
- 26th June 2008 at 09:20Permalink- Edited 1st January 1970 at 01:00
A hopeless case, when it comes to the understanding of the basics of physics. To read something and do understand the meaning of that are two different worlds sometimes.
So someone has to live with the mystery, that the F-111 can generate at least 1/3 more range from every kg of fuel carried over the Su-24.
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By: MiG-23MLD
- 26th June 2008 at 13:46Permalink- Edited 1st January 1970 at 01:00
No no no. A jet is rarely in ballistic flight, and never in cruise.
:rolleyes:
This is a mass of irrelevancy. Thrust to weight ratio and acceleration have nothing to do with range or fuel consumption in cruise. A jet is not an ICBM. Sens knows more about the issues here than I do, so I'm not going to wade into this fencing match, but you are clearly lost in the dark.
No, it gets lift from its body. But I very much doubt it reaches any equilibrium between thrust and drag before burnout, so it doesn't cruise either.
The Saturn V does not fly. A glider flies. A Saturn V is ballistic.
hehehe or shall i say hahahaha, all of us are in a parabolic trajectory, why? because the the planet is round and spining in its own axis even wabbling, if the earth was flat you can say all airplanes fly and rockets have parabolic trajectories, however if you know the concept of limit taken from calculus, you know when X is close to 0 the Gradient seem to be a point but when X is X>0 or bigger than zero it seems to be a slope, however for our planet a plane is flying a parabolic trajectory due to gravity, in fact if you do not follow a parabolic trajectory you will get out of the earth`s gravity and go into orbit or out of earth`s gravity pull
Since you can not see thet kilo newtons is a measure to see force and to see the acceleration a mass can reach then you can not see a lighter mass will get higher acceleration, the Su-24 is lighter and has a higher thrust at military power therefore it needs less kilo newtons to achieve the same speed an F-111
W = mg
W = (1 kg)(9.807 m/s²)
W = 9.807
This proves you that gravity exerts to a mass of one kilo 9.8 newtons, a higher thrust to weight ratio exerts then higher acceleration and therefore the Al-21 is not using its max SFC it has when it has the same thrust the TF-30 has its max SFC at military power
By: MiG-23MLD
- 26th June 2008 at 13:50Permalink- Edited 1st January 1970 at 01:00
A hopeless case, when it comes to the understanding of the basics of physics. To read something and do understand the meaning of that are two different worlds sometimes.
So someone has to live with the mystery, that the F-111 can generate at least 1/3 more range from every kg of fuel carried over the Su-24.
hahahaha yeah yeah so kilo newtons are not the real measure for thrust eh? niether mean the acceleration a mass can get for a given mass in time yeah Sens yeah a hopeless case true if you think thrust is not an element that keeps an airplane flying, lift is also another element but not the only one, planes use lift but also speed in the same way a satellite in orbit goes fast to avoid falling into earth
In the SI system, the three fundamental quantities are mass, length, and time. The units are kilograms (kg) for mass, meter (m) for length, and second (s) for time. The force unit is called a newton (N), and is defined as the force required to accelerate a mass of 1 kg at a rate of 1 meter/sec. Mathematically expressed;
Specifications (AL-21F-3)
General characteristics
Type: Afterburning turbojet
Length: 5,300 mm (209 in)
Diameter: 1,000 mm (39 in)
Dry weight: 1,700 kg (3,740 lb)
Components
Compressor: 14-stage axial compressor with variable stator blades
Performance
Thrust:76.4 kN (17,175 lbf) dry
109.8 kN (24,675 lbf) with afterburner
Overall pressure ratio: 14.75:1
Turbine inlet temperature: 1,100 °C (2,000 °F)
Specific fuel consumption:
77.5 kg/(h·kN) (0.76 lb/(h·lbf)) at idle
87.7 kg/(h·kN) (0.86 lb/(h·lbf)) at maximum military power
189.7 kg/(h·kN) (1.86 lb/(h·lbf)) with afterburner
Thrust-to-weight ratio: 64.7 N/kg (6.6:1)
By: Rocky
- 26th June 2008 at 15:54Permalink- Edited 1st January 1970 at 01:00
hehehe or shall i say hahahaha, all of us are in a parabolic trajectory, why? because the the planet is round and spining in its own axis even wabbling,
Because the planet is round????? So what would the Earth's orbit look like if the earth was shaped like a cube?? :rolleyes:
if the earth was flat you can say all airplanes fly and rockets have parabolic trajectories, however if you know the concept of limit taken from calculus, you know when X is close to 0 the Gradient seem to be a point but when X is X>0 or bigger than zero it seems to be a slope, however for our planet a plane is flying a parabolic trajectory due to gravity, in fact if you do not follow a parabolic trajectory you will get out of the earth`s gravity and go into orbit or out of earth`s gravity pull
Airplanes DO NOT follow a parabolic trajectory, unless they are falling and pulling 0 g. Astronauts train for 0 g in a 707(?) that flies in an arc to achieve 0 g. Thats approximately a parabolic flight. I suppose you could say a plane in level flight is travelling in a circle, because the Earth is round and the plane would fly all they way around the Earth if it had enough fuel - but its not going nearly fast enough to say its in orbit.
Since you can not see thet kilo newtons is a measure to see force
"Newton" is a unit of force, not "kilo newton".
and to see the acceleration a mass can reach then you can not see a lighter mass will get higher acceleration, the Su-24 is lighter and has a higher thrust at military power therefore it needs less kilo newtons to achieve the same speed an F-111
No, the Su-24 is not a rocket in space. The top speed is all determined by thrust and drag. Mass is only an issue in acceleration. I think Sens told you that too.
This proves you that gravity exerts to a mass of one kilo 9.8 newtons, a higher thrust to weight ratio exerts then higher acceleration and therefore the Al-21 is not using its max SFC it has when it has the same thrust the TF-30 has its max SFC at military power
This is total nonsense.
rocky are you still in the middle ages when people thought the world was flat?
Actually, its funny you should say that. You wrote that objects follow a parabolic trajectory. When one calculates the path of an artillery shell on a parabolic trajectory, that is actually a simplified approximation that assumes a vacuum and that the Earth is flat. It works over short distances. At less than escape velocity, objects in ballistic motion are actually following the path of an ellipse. The Earth goes around the Sun in an ellipse, satelites go around the Earth in an ellipse, and when you throw a rock, its path is an ellipse, until it runs into something like the ground. An object travelling faster than escape velocity follows a hyperbolic trajectory. An object travelling exactly at escape velocity follows the path of a parabola.
New
Posts: 3,010
By: MiG-23MLD
- 26th June 2008 at 16:23Permalink- Edited 1st January 1970 at 01:00
Because the planet is round????? So what would the Earth's orbit look like if the earth was shaped like a cube?? :rolleyes:
Airplanes DO NOT follow a parabolic trajectory, unless they are falling and pulling 0 g. Astronauts train for 0 g in a 707(?) that flies in an arc to achieve 0 g. Thats approximately a parabolic flight. I suppose you could say a plane in level flight is travelling in a circle, because the Earth is round and the plane would fly all they way around the Earth if it had enough fuel - but its not going nearly fast enough to say its in orbit.
"Newton" is a unit of force, not "kilo newton".
No, the Su-24 is not a rocket in space. The top speed is all determined by thrust and drag. Mass is only an issue in acceleration. I think Sens told you that too.
This is total nonsense.
Actually, its funny you should say that. You wrote that objects follow a parabolic trajectory. When one calculates the path of an artillery shell on a parabolic trajectory, that is actually a simplified approximation that assumes a vacuum and that the Earth is flat. It works over short distances. At less than escape velocity, objects in ballistic motion are actually following the path of an ellipse. The Earth goes around the Sun in an ellipse, satelites go around the Earth in an ellipse, and when you throw a rock, its path is an ellipse, until it runs into something like the ground. An object travelling faster than escape velocity follows a hyperbolic trajectory. An object travelling exactly at escape velocity follows the path of a parabola.
I know kilo newton means 1000 newtons and when i posted it was written like that, however kilonewtons are used for aircraft engines.
I have never said the the wing`s lift is not a element that makes an aircraft fly, however it is not the only fact, wings also work as stabilizing aerodynamic surfaces.
Now let us see why i said i said that the AL-21 has a max SFC at military power of 0.86 kilograms per kgf/kg/h, now the TF-30 has a max SFC of 0.67kgf/kg/h, however their max military power is different the AL-21F3 is a 79KN engine at military power, in the TF-30-P-100`s case it is lower it has a max military power of around 66KN, the AL-21F3 at 66KN has not a SFC of 0.86kgf/kg/h its SFC at that thrust of course is lower and since the Su-24 is lighter needs less thrust to acheive the same speed a heavier F-111 needs
for that reason the Russians never felt so compelled to build Su-24 variants with turbofans, the AL-31 is another history since it has a Max military power of 79KN and a SFC at military power of 0.75kgf/kg/h, however it meant a different inlet system for the Su-24, something that sukhoi was unwilling to do and never did
By: Sens
- 26th June 2008 at 23:37Permalink- Edited 1st January 1970 at 01:00
Now let us see why i said i said that the AL-21 has a max SFC at military power of 0.86 kilograms per kgf/kg/h, now the TF-30 has a max SFC of 0.67kgf/kg/h, however their max military power is different the AL-21F3 is a 79KN engine at military power, in the TF-30-P-100`s case it is lower it has a max military power of around 66KN, the AL-21F3 at 66KN has not a SFC of 0.86kgf/kg/h its SFC at that thrust of course is lower and since the Su-24 is lighter needs less thrust to acheive the same speed a heavier F-111 needs
"77.5 kg/(h·kN) (0.76 lb/(h·lbf)) at idle"
The one able to read the own writings is in advantage about that, is he?!!!!!!!
For a Su-24 or F-111 it is lift what carries the weight or counter the G forces.
For a Su-24 or F-111 it is thrust what does counter the drag.
New
Posts: 3,010
By: MiG-23MLD
- 27th June 2008 at 01:09Permalink- Edited 1st January 1970 at 01:00
"77.5 kg/(h·kN) (0.76 lb/(h·lbf)) at idle"
The one able to read the own writings is in advantage about that, is he?!!!!!!!
Sens i did make a mistake and i recognize it i did not read well, the real military power SFC for the AL-21F3 is 0.86kgf/kg/h. and the 0.76 SFC is not like you are saying idle it is at economic cruise and i can prove it, however you should see that the 0.86 SFC is achieved with 15% more thrust, so the difference in SFC is not reflected in 30% more fuel burnt at the same thrust
see
Удельный расход топлива:, (кг/ч)/Н SFC
- на максимальном режиме 0.86 at max military power 0.86
- на форсаже 1.86 at full after burner
- минимальный 0.76 minimal
Parameters Thrust, kg r.p.m. Compr. Ratio
Maximum reheat 11250 8316 14.55
Minimum reheat 9700 8316 14.55
Maximum regime 7800+234 8316 14.55
Minimal fuel consumption mode 3300:4500 6890;7400 9.0;11.35
Idling 350 http://www.rbs.ru/vttv/99/firms/baranov/e-al21.htm
So efectively the max military SFC of the AL-21F3 is 30% more fuel thirsty than the TF-30`s SFC at its max military power , you are right in that sense, however the real thrust is not the same, the SFC of the AL-21 is achieved at a higher thrust of 15% more KN.
So you can not say the AL-21 is 30% less economical since the 0.67 SFC number is achieved by the Tf-30-P-100 with 15% less thrust, so the TF-30-P-100 at 79KN is already at afteburner and its SFC at afterburner is in fact higher than the AL-21 at the same power setting.
I think and i say honestly that the Su-24 is more fuel thirsty but the difference is still should consider max internal fuel and SFC at the same thrust.
The minimal thrust the Al-21 can have is 3300kg thrust and idle is 300kgs
By: franc
- 27th June 2008 at 11:37Permalink- Edited 1st January 1970 at 01:00
A hopeless case, when it comes to the understanding of the basics of physics. To read something and do understand the meaning of that are two different worlds sometimes.
So someone has to live with the mystery, that the F-111 can generate at least 1/3 more range from every kg of fuel carried over the Su-24.
The prescribe minimum range Su-24 had is 2775km from Sukhoi web, same data of the F-111 is 3700km from JAWA. the rate is 0.75 where does your 1/3 come from?
We admitted turbofan is superior than Turbojet, but as we quoted previously, the SFC of the TF30 has no 1/3 advantage more than AL-21 neither on afterburner nor without afterburner.
Lacking fuel tank in wing a cause de internal fuel of the Su-24 less than F-111 but, bomb bay also occupied space in fuselage of the F-111, so 11 ton for Su-24 and 14tons for the F-111 also is reliable and reasonable. the rate is approxi to 3/4, where does 1/3 range at least base on?
Posts: 3,010
By: MiG-23MLD - 25th June 2008 at 02:23 Permalink - Edited 1st January 1970 at 01:00
So now we have the mistery thrust, the mystery thrust!:eek: Sens is the TF-30 a ramjet? ramjets only work at speeds of Mach 3 or more, the F-111 is no more than a Mach 2.5 speed aircraft, its inlet only reduces the amount of fuel needed but still it has a specific thrust, using a fan the turbofan reduces the amount of fuel spent, but still a turbofan can not work beyond a specific subsonic flow, besides big turbofans with high by pass ratios are for subsonic speeds and commercial aircraft and beyond that ramjets and turbofans with very low by pass ratios are more practical, these low by pass ratios are not very different from a turbojet in reality. So the AL-21 will spend more fuel to produce the same thrust because it sucks less air, however its thrust is higher at military power, the TF-30 is a low by pass ratio engine not a high by pass ratio like a Trent 900
This Trent 900 high by pass turbofan has a simple inlet nacelle cowling with no ramp or even VG ramp
So Sens this explains you why the TF-30 is not more different than the AL-21 at full afterburner, simply because the by pass ratio is still low.
When you fly at speeds beyond Mach 3 the ramjet can start working.
Now you have to see a reality, the TF-30 has lower yield and has to power a heavier aircraft, but of course you are in one way belittling the Al-21F3 used by the Su-24, this engine might be more fuel thirsty in SFC and this is not by 10% but only 8% at full military power, this engine however will power a lighter aircraft and has a higher thrust at military power.
Sukhoi claims the MTOW for the Su-24MK is slightly more than 43000kg and the RAAF claims the F-111 has a MTWO of almost 52000kg, see that the difference in absolute ferry range at max fuel weight, has a difference in fuel weight of almost 11000kg between both aircraft, that ratio is almost the same in range and in max fuel capacity
Posts: 620
By: franc - 25th June 2008 at 05:36 Permalink - Edited 1st January 1970 at 01:00
The size of Tu-22 almost same as B-1, so it is hard to say, Tu-22 is a sort of bomber which is more efficient than neither F-111 or Su-24.
The undercarriger was designed on F-111 makes inlet shorter so that structual weight reduced. Dual-wheel which Su-24 undercarriage used gives a using flexible for wild runway but more space in aeroframe occupied.
Posts: 3,010
By: MiG-23MLD - 25th June 2008 at 16:48 Permalink - Edited 1st January 1970 at 01:00
The Tu-22M is in a total different class from the F-111, however the irony is the FB-111 tried to fill the same niche successfully, but it failed and today the Tu-22M remains one of the most sucessful bombers of all time.
The F-111 might have a SFC more economical but at lower thrust.
Posts: 11,742
By: Sens - 25th June 2008 at 17:06 Permalink - Edited 1st January 1970 at 01:00
When someone is unable or at best unwilling to understand some basic, there is no problem to accept that. But it becomes worse, when someone tries to distract from that shortcomings through further ridiculous claims.
For the benefit of the others.
The flow of air does behave different with different speeds.
There is the true subsonic range below Mach 0,7 - the transonic range - the true supersonic range and the high supersonic range.
For take-off and climb most aircraft do operate in the true subsonic range, when for cruise they stay in the lower transonic-range at around Mach 0,8.
The best suited engine is the high bypass TF with 4:1 up to 10+:1 or the TP
of 100:1 sticking to the true subsonic range only.
Military TFs are at 1,5:1 or lower, related to the wider speed range.
Military Tj are at best at true supersonic or behind Mach 1,2. The best possible military engine will one with a variable cycle. That was the promise with the first GE F120 engine, which was too futuristic for the USAF.
The low by-path PW F119 does offer the best available compromise between lower fuel consumption of a TF and still good enough at supersonic.
The best compromise for fighters was 0,5:1 in the 80s or lower. Below of 0,5:1 such engines are called "leaky Tj".
Possible through the gains in pressure-ratio and TET.
But for someone I have to push the basics to the limits, despite little hope about that.
The V10 engine of a F1 Ferrari did deliver 925 hp at 19.800 U/min.
The V12 engine of a T-72 MBT did deliver 780 hp at ~2000 U/min.
Nominal the Ferrari engine has a higher output in hp, but none will get the idea to put that into the T-72 MBT?!
Can it be, that hp or kp are not the single yardstick about force?!
The bypath-ratio of the TF30 did differ between 1,1:1 to 17,1 pressure ratio or 0,7:1 to 22 pressure ratio.
Every variant of that was on the higher side of bypath-ratio for military engines (up to 1,5:1)
I never got the idea, that someone may try to compare that to present airliner-engines and their limited flying envelope to operate.
To save my time, I will not explain how an AB does work. (As the related AB-ratios and the related sfc) That does not make sense about the lack of understanding about the basics and the limited use in striker-missions.
Even the math is limited. Please try it again.
0,69 = 100
0,76 = X
The next fancy "highlight" is about MTOW.
The ferry-range is related to the amount of fuel at take-off, whatever you prefer, be it kg or liter. (conversion-rate is ~0,77 kg per liter).
The yardstick is, how far can you go in km for every kg or liter?!
Filling the same amount of fuel into into a Su-24 and the F-111 does bring a remarkable difference in range from that, well behind the difference in SFC.
Posts: 3,010
By: MiG-23MLD - 25th June 2008 at 17:37 Permalink - Edited 1st January 1970 at 01:00
Why you forget simple details you that always claim to know details?
You clearly know by simple physics an aircraft needs a force to achieve a speed when it weighs a specific mass and in an aircraft you have to consider gravity and air drag.
you know perfectly the F-111 at full military power has a lower Thrust to weight ratio than the Su-24 at full military power, perhaps at subsonic cruise speeds the F-111 is more economical but carrying a heavy load it won`t fly too fast either due to weight
The inlet was designed to disaccelerate the supersonic flow to subsonic speeds, a true ramjet has not such limitations since already air preasure and compression is achieved by the speed the airplane flies, so no need for compressor or blades, however the turbofan and you know it very well can not work with a supersonic flow, it compresses the air but not due to speed since the ramp and duct slow down the supersonic flow to subsonic speeds, and for such a reason you have a ramp or even an variable geometry ramp that generates multishock waves.
A scram jet even can work at supersonic speeds of air flow.
With engines like the TF-30 and AL-21, you have a very similar yield of 11000kg thrust, however one engine compresses air more and needs therefore less fuel to produce thrust however it has lower thrust at military power ask your self at the same max military thrust of the TF-30 the AL-21 does not have its max military power and does not spend the same amount of fuel at a SFC of 0.86, but has a lower fuel consumption .
In a high by pass engine like the Trent 900 you do not need a ramp simply because air is not traveling supersonic so there is no need for a ramp to slow down the supersonic flow however with the olympus fitted to the Concord you need a ramp and the same happens with the F-101 that powers the B-1A and B-1B
Posts: 11,742
By: Sens - 25th June 2008 at 18:55 Permalink - Edited 1st January 1970 at 01:00
Please read carefully and do sleep a night about that.
Even the simple math you left aside.
The engine has nothing to do with the weight of a flying aircraft at first.
The counterforce of weight is the lift.
That lift is generated by lifting areas and speed. (The single exception are VTOL aircraft).
The more weight you will bring into the air the more lift you are in need of.
A Su-24 or F-111 are in need of lifting areas to do so and some related controls for stability.
But that lift is not for free. In a similar way you rise lift by that, you have to counter the related rise in drag, when doing so.
To counter that drag, you are in need of a propulsion-system. One central part of that is the engine to accelerate to lift-off speed and overcome the flying drag.
The trick is to get the most lift for the least drag. (One of the main advantages of the VG-design).
When doing so you do reduce the need of thrust to overcome the related drag.
Related to your minimum demand in lift you will choose the least draggy speed to do so, which is subsonic in general. The best engine for that is an engine, which does operate close to its optimum cycle, when doing so.
A TF has two cycles to benefit from, when the Tj has a single cycle, which can not adjusted in a similar way to the related power-demands.
In the meanwhile it is common knowledge, that the drag-thrust ratio is the most important yardstick. For the lack of published data about that, some got the idea to use the installed thrust to have a rough yardstick.
When assuming, that in the 50s all jets did have a similar drag, a similar jet-engine, that may have worked some way, just to give the public an idea about that.
That was never true as it its with different designs and technology.
Posts: 3,010
By: MiG-23MLD - 26th June 2008 at 01:06 Permalink - Edited 1st January 1970 at 01:00
You theory is only part true and over simplistic, why? let us start by simple physics
The newton (symbol: N) is the SI unit of force. It is named after Sir Isaac Newton in recognition of his work on classical mechanics.A newton is the amount of force required to accelerate a mass of one kilogram at a rate of one meter per second squared. In addition
http://www.convertworld.com/en/weight/Kilonewton.html
A jet engine measures thrust in Kilo newtons, the Russians usually do it, SFC only reflects the amount of fuel to accelerate kilo newtons.
In a jet engine, air is compressed by a turbine. Fuel is added to this air and is exhausted out the other end. This gas exerts an equal reaction force, providing forward thrust as it exits the engine. This thrust is transmitted from the engine to an airframe and engine mountings to propel the aircraft. Thrust is measured in pounds (lb), kilogram force (kgf), or the international unit, newtons (N).
http://hypertextbook.com/facts/2000/KennethKwan.shtml
Now an aircraft fights gravity by two simple forces, centrifugal force and lift
Fc = mv2/r, where Fc = centrifugal force, m = mass, v = speed, and r = radius
and we can say that despite for us the F-111 or Su-24 are flying straight, in reality they are traveling in a gravitational parabolic path in the same way a cannon ball flies however they constantly burn fuel and fly straight in our reference point of view
parabolic trajectory. The downward force of gravity would act upon the cannonball to cause the same vertical motion as before - a downward acceleration.
now since we are not in the vaccum the F-111 and Su-24 will experience drag, however by simple physics we know An object in motion would continue in motion at a constant speed in the same direction if there is no unbalanced force so our F-111 or Su-24 will slow down due to air drag or in other words friction.
Know if the Su-24 and F-111 have different masses, the same amount of kilo newton force will accelerate them differently since they have a difference in weight.
If the Max military power of the TF-30 is lower then the SFC of the AL-21 at the same thrust will be lower and therefore more efficient than you really expect, now if the Su-24 is lighter and has higher thrust to weight ratio at full military power you can not expect the aircraft to be less fuel efficient as you claim, however in aboslute numbers the F-111 has a longer range and higher payload, in that sense the F-111 is a more efficient aircraft by packing a higher density at a given volume
Now the SRAAM AIM-132 shows you an AAM can fly by just thrust alone
The Saturn V also is wingless and flies
Posts: 483
By: Rocky - 26th June 2008 at 08:25 Permalink - Edited 1st January 1970 at 01:00
No no no. A jet is rarely in ballistic flight, and never in cruise. :rolleyes:
This is a mass of irrelevancy. Thrust to weight ratio and acceleration have nothing to do with range or fuel consumption in cruise. A jet is not an ICBM. Sens knows more about the issues here than I do, so I'm not going to wade into this fencing match, but you are clearly lost in the dark. No, it gets lift from its body. But I very much doubt it reaches any equilibrium between thrust and drag before burnout, so it doesn't cruise either. The Saturn V does not fly. A glider flies. A Saturn V is ballistic.
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By: Sens - 26th June 2008 at 09:20 Permalink - Edited 1st January 1970 at 01:00
A hopeless case, when it comes to the understanding of the basics of physics. To read something and do understand the meaning of that are two different worlds sometimes.
So someone has to live with the mystery, that the F-111 can generate at least 1/3 more range from every kg of fuel carried over the Su-24.
Posts: 3,010
By: MiG-23MLD - 26th June 2008 at 13:46 Permalink - Edited 1st January 1970 at 01:00
hehehe or shall i say hahahaha, all of us are in a parabolic trajectory, why? because the the planet is round and spining in its own axis even wabbling, if the earth was flat you can say all airplanes fly and rockets have parabolic trajectories, however if you know the concept of limit taken from calculus, you know when X is close to 0 the Gradient seem to be a point but when X is X>0 or bigger than zero it seems to be a slope, however for our planet a plane is flying a parabolic trajectory due to gravity, in fact if you do not follow a parabolic trajectory you will get out of the earth`s gravity and go into orbit or out of earth`s gravity pull
Since you can not see thet kilo newtons is a measure to see force and to see the acceleration a mass can reach then you can not see a lighter mass will get higher acceleration, the Su-24 is lighter and has a higher thrust at military power therefore it needs less kilo newtons to achieve the same speed an F-111
W = mg
W = (1 kg)(9.807 m/s²)
W = 9.807
This proves you that gravity exerts to a mass of one kilo 9.8 newtons, a higher thrust to weight ratio exerts then higher acceleration and therefore the Al-21 is not using its max SFC it has when it has the same thrust the TF-30 has its max SFC at military power
rocky are you still in the middle ages when people thought the world was flat?
http://links999.net/cartography/cartography_history.html
or is this you idea of the world
Posts: 3,010
By: MiG-23MLD - 26th June 2008 at 13:50 Permalink - Edited 1st January 1970 at 01:00
hahahaha yeah yeah so kilo newtons are not the real measure for thrust eh? niether mean the acceleration a mass can get for a given mass in time yeah Sens yeah a hopeless case true if you think thrust is not an element that keeps an airplane flying, lift is also another element but not the only one, planes use lift but also speed in the same way a satellite in orbit goes fast to avoid falling into earth
In the SI system, the three fundamental quantities are mass, length, and time. The units are kilograms (kg) for mass, meter (m) for length, and second (s) for time. The force unit is called a newton (N), and is defined as the force required to accelerate a mass of 1 kg at a rate of 1 meter/sec. Mathematically expressed;
1 N = (1 kg)(1 m/s²) or 1 N = 1 kg.m/s²
http://www.southeastclimbing.com/faq/faq_kilonewton.htm
Specifications (AL-21F-3)
General characteristics
Type: Afterburning turbojet
Length: 5,300 mm (209 in)
Diameter: 1,000 mm (39 in)
Dry weight: 1,700 kg (3,740 lb)
Components
Compressor: 14-stage axial compressor with variable stator blades
Performance
Thrust:76.4 kN (17,175 lbf) dry
109.8 kN (24,675 lbf) with afterburner
Overall pressure ratio: 14.75:1
Turbine inlet temperature: 1,100 °C (2,000 °F)
Specific fuel consumption:
77.5 kg/(h·kN) (0.76 lb/(h·lbf)) at idle
87.7 kg/(h·kN) (0.86 lb/(h·lbf)) at maximum military power
189.7 kg/(h·kN) (1.86 lb/(h·lbf)) with afterburner
Thrust-to-weight ratio: 64.7 N/kg (6.6:1)
http://en.wikipedia.org/wiki/Lyulka_AL-21
Posts: 483
By: Rocky - 26th June 2008 at 15:54 Permalink - Edited 1st January 1970 at 01:00
Because the planet is round????? So what would the Earth's orbit look like if the earth was shaped like a cube?? :rolleyes: Airplanes DO NOT follow a parabolic trajectory, unless they are falling and pulling 0 g. Astronauts train for 0 g in a 707(?) that flies in an arc to achieve 0 g. Thats approximately a parabolic flight. I suppose you could say a plane in level flight is travelling in a circle, because the Earth is round and the plane would fly all they way around the Earth if it had enough fuel - but its not going nearly fast enough to say its in orbit."Newton" is a unit of force, not "kilo newton". No, the Su-24 is not a rocket in space. The top speed is all determined by thrust and drag. Mass is only an issue in acceleration. I think Sens told you that too. This is total nonsense.
Actually, its funny you should say that. You wrote that objects follow a parabolic trajectory. When one calculates the path of an artillery shell on a parabolic trajectory, that is actually a simplified approximation that assumes a vacuum and that the Earth is flat. It works over short distances. At less than escape velocity, objects in ballistic motion are actually following the path of an ellipse. The Earth goes around the Sun in an ellipse, satelites go around the Earth in an ellipse, and when you throw a rock, its path is an ellipse, until it runs into something like the ground. An object travelling faster than escape velocity follows a hyperbolic trajectory. An object travelling exactly at escape velocity follows the path of a parabola.
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By: MiG-23MLD - 26th June 2008 at 16:23 Permalink - Edited 1st January 1970 at 01:00
I know kilo newton means 1000 newtons and when i posted it was written like that, however kilonewtons are used for aircraft engines.
I have never said the the wing`s lift is not a element that makes an aircraft fly, however it is not the only fact, wings also work as stabilizing aerodynamic surfaces.
Now let us see why i said i said that the AL-21 has a max SFC at military power of 0.86 kilograms per kgf/kg/h, now the TF-30 has a max SFC of 0.67kgf/kg/h, however their max military power is different the AL-21F3 is a 79KN engine at military power, in the TF-30-P-100`s case it is lower it has a max military power of around 66KN, the AL-21F3 at 66KN has not a SFC of 0.86kgf/kg/h its SFC at that thrust of course is lower and since the Su-24 is lighter needs less thrust to acheive the same speed a heavier F-111 needs
for that reason the Russians never felt so compelled to build Su-24 variants with turbofans, the AL-31 is another history since it has a Max military power of 79KN and a SFC at military power of 0.75kgf/kg/h, however it meant a different inlet system for the Su-24, something that sukhoi was unwilling to do and never did
Posts: 11,742
By: Sens - 26th June 2008 at 23:37 Permalink - Edited 1st January 1970 at 01:00
"77.5 kg/(h·kN) (0.76 lb/(h·lbf)) at idle"
The one able to read the own writings is in advantage about that, is he?!!!!!!!
Posts: 11,742
By: Sens - 26th June 2008 at 23:40 Permalink - Edited 1st January 1970 at 01:00
http://www.fi.edu/flights/own2/forces.html
For a Su-24 or F-111 it is lift what carries the weight or counter the G forces.
For a Su-24 or F-111 it is thrust what does counter the drag.
Posts: 3,010
By: MiG-23MLD - 27th June 2008 at 01:09 Permalink - Edited 1st January 1970 at 01:00
Sens i did make a mistake and i recognize it i did not read well, the real military power SFC for the AL-21F3 is 0.86kgf/kg/h. and the 0.76 SFC is not like you are saying idle it is at economic cruise and i can prove it, however you should see that the 0.86 SFC is achieved with 15% more thrust, so the difference in SFC is not reflected in 30% more fuel burnt at the same thrust
see
Удельный расход топлива:, (кг/ч)/Н SFC
- на максимальном режиме 0.86 at max military power 0.86
- на форсаже 1.86 at full after burner
- минимальный 0.76 minimal
http://www.airwar.ru/enc/engines/al21f.html
Удельный расход топлива, кг/кгс·ч.: SFC
на форсажном режиме 1,90 1.86 at full afterburner
на крейсерском режиме 0.72 0.76 at cruising regime
http://aviaros.narod.ru/al-21f.htm
Parameters Thrust, kg r.p.m. Compr. Ratio
Maximum reheat 11250 8316 14.55
Minimum reheat 9700 8316 14.55
Maximum regime 7800+234 8316 14.55
Minimal fuel consumption mode 3300:4500 6890;7400 9.0;11.35
Idling 350 http://www.rbs.ru/vttv/99/firms/baranov/e-al21.htm
So efectively the max military SFC of the AL-21F3 is 30% more fuel thirsty than the TF-30`s SFC at its max military power , you are right in that sense, however the real thrust is not the same, the SFC of the AL-21 is achieved at a higher thrust of 15% more KN.
So you can not say the AL-21 is 30% less economical since the 0.67 SFC number is achieved by the Tf-30-P-100 with 15% less thrust, so the TF-30-P-100 at 79KN is already at afteburner and its SFC at afterburner is in fact higher than the AL-21 at the same power setting.
I think and i say honestly that the Su-24 is more fuel thirsty but the difference is still should consider max internal fuel and SFC at the same thrust.
The minimal thrust the Al-21 can have is 3300kg thrust and idle is 300kgs
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By: Sens - 27th June 2008 at 09:04 Permalink - Edited 1st January 1970 at 01:00
So you still have to explain, where the difference in fuel economy comes from?
F-111 = 5,66 l per km
Su-24 = 7,41 l per km
From every l of fuel a F-111 generates 30,9% more range!
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By: tomcat1974 - 27th June 2008 at 09:19 Permalink - Edited 1st January 1970 at 01:00
Lower drag? More efficient Wing design? Just better aerodynamics?:rolleyes:
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By: franc - 27th June 2008 at 11:37 Permalink - Edited 1st January 1970 at 01:00
The prescribe minimum range Su-24 had is 2775km from Sukhoi web, same data of the F-111 is 3700km from JAWA. the rate is 0.75 where does your 1/3 come from?
We admitted turbofan is superior than Turbojet, but as we quoted previously, the SFC of the TF30 has no 1/3 advantage more than AL-21 neither on afterburner nor without afterburner.
Lacking fuel tank in wing a cause de internal fuel of the Su-24 less than F-111 but, bomb bay also occupied space in fuselage of the F-111, so 11 ton for Su-24 and 14tons for the F-111 also is reliable and reasonable. the rate is approxi to 3/4, where does 1/3 range at least base on?
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By: franc - 27th June 2008 at 11:58 Permalink - Edited 1st January 1970 at 01:00
The dividend you adopted is wrong.