By: Anonymous
- 18th June 2008 at 21:25Permalink- Edited 22nd October 2019 at 22:29
At roughly similar OEW and size, which let's room for the question, what the Suchoi engineers did with all the volume? Stuffed it with analogue electronics?
The bulky electronics are probably part of the reason on earlier Fencer variants in particular and the Su-24M has both an interal gun and an internal laser designator installed at the same time. Meanwhile the F-111 carries either one OR the other in its internal bomb bay, optionally foregoing both in favour of more fuel. AFAIK, in practice the bay was rarely used for anything other than those loads, except on the FB-111 where it actually housed weapons (SRAMs).
Not sure how much this eats into the volume available for fuel, but it will have had some effect.
By: Schorsch
- 18th June 2008 at 22:01Permalink- Edited 1st January 1970 at 01:00
The bulky electronics are probably part of the reason on earlier Fencer variants in particular and the Su-24M has both an interal gun and an internal laser designator installed at the same time. Meanwhile the F-111 carries either one OR the other in its internal bomb bay, optionally foregoing both in favour of more fuel. AFAIK, in practice the bay was rarely used for anything other than those loads, except on the FB-111 where it actually housed weapons (SRAMs).
Not sure how much this eats into the volume available for fuel, but it will have had some effect.
The bomb bay was planned as the F-111 was required to make the last 180nm supersonic. It actually never achieved that mark.
For delivering the nuclear bomb a bomb makes sense, for anything else it is not very useful (except for stealthy aircraft).
Fitting a gun into such an aircraft seems doubtful.
As I said, the F-111 was slightly overengineered.
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By: MiG-23MLD
- 19th June 2008 at 04:37Permalink- Edited 1st January 1970 at 01:00
The bulky electronics are probably part of the reason on earlier Fencer variants in particular and the Su-24M has both an interal gun and an internal laser designator installed at the same time. Meanwhile the F-111 carries either one OR the other in its internal bomb bay, optionally foregoing both in favour of more fuel. AFAIK, in practice the bay was rarely used for anything other than those loads, except on the FB-111 where it actually housed weapons (SRAMs).
Not sure how much this eats into the volume available for fuel, but it will have had some effect.
In my opinion and i remark it is just an expeculation, the Su-24 has different shape and therefore it does not have the same ability to house fuel tanks.
The Su-24 for example has longer and narrower inlets; the shorter and wider inlets inlets in the F-111 allows in my opinion larger volume capacity fuel tanks since the shorter but wider inlet ducts are not so deeply buried in the fuselage, also the F-111 has bigger wing gloves and contrary to the longer and more deeply buried fuselage inlet ducts that the Su-24 has. the wing gloves can house fuel in the F-111.
Probably this different shape and form account for part of the difference in fuel volume capacity plus the Su-24 is slightly longer and might have heavier avionics
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By: MiG-23MLD
- 20th June 2008 at 03:35Permalink- Edited 1st January 1970 at 01:00
The bomb bay was planned as the F-111 was required to make the last 180nm supersonic. It actually never achieved that mark.
For delivering the nuclear bomb a bomb makes sense, for anything else it is not very useful (except for stealthy aircraft).
Fitting a gun into such an aircraft seems doubtful.
As I said, the F-111 was slightly overengineered.
An early Su-24 might look like it had a wider gap between the engine nacelles
however in this picture is clear the F-111 has a wider gap between the engine nacelles
In the same way in this picture it is clear the Su-24 has a narrower fuselage and a narrower engine gap with each other see
By: franc
- 21st June 2008 at 14:09Permalink- Edited 1st January 1970 at 01:00
How large the fuselage is not only depands on the gap between the engine nacelles but also depands on the size of engine. meanwhile,
how many fuel the fuselage carry not only depands on the size of fuselage but also the size of engine.
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By: MiG-23MLD
- 23rd June 2008 at 04:44Permalink- Edited 1st January 1970 at 01:00
How large the fuselage is not only depands on the gap between the engine nacelles but also depands on the size of engine. meanwhile,
how many fuel the fuselage carry not only depands on the size of fuselage but also the size of engine.
The TF-30 and Al-21 are almost the same size and ironically, the TF-30 is slightly bigger, however it is obvious the Su-24 has a slimmer fuselage and smaller wing gloves, and in general dimensions is slightly larger, that is the only way to explain the smaller fuel capacity it has.
By: Sens
- 23rd June 2008 at 17:56Permalink- Edited 1st January 1970 at 01:00
The TF-30 and Al-21 are almost the same size and ironically, the TF-30 is slightly bigger, however it is obvious the Su-24 has a slimmer fuselage and smaller wing gloves, and in general dimensions is slightly larger, that is the only way to explain the smaller fuel capacity it has.
Good finding. Look into the cutaways of both aircrafts and you will find out, where that "extra" fuel is housed.
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By: MiG-23MLD
- 24th June 2008 at 01:44Permalink- Edited 1st January 1970 at 01:00
Good finding. Look into the cutaways of both aircrafts and you will find out, where that "extra" fuel is housed.
independently of the riddle, the Su-24 has only fuselage fuel tanks and the F-111 has wing internal fuel tanks, however the Su-24 has narrower fuselage.
By: Sens
- 24th June 2008 at 15:59Permalink- Edited 1st January 1970 at 01:00
independently of the riddle, the Su-24 has only fuselage fuel tanks and the F-111 has wing internal fuel tanks, however the Su-24 has narrower fuselage.
Wing internal fuel tanks is OK. The second point is about the landing-gear.
Every technological decision has its price. Another is about external load stations related to VG.
By: Schorsch
- 24th June 2008 at 20:37Permalink- Edited 1st January 1970 at 01:00
Why there is no fuel tank in Su-24's wing? forgot?
Yes, just forgotten. Someone put the specs in the trash before design was finished. Was a long night again in the design office.
Anyways, a fuel tank in a swept wing comes with price in weight and complexity. It also has a structural knock-on effect, for example on the already highly loaded pivots. So, if your specs don't ask for more range, you cancel that.
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By: Jon James
- 24th June 2008 at 20:39Permalink- Edited 1st January 1970 at 01:00
Yes, just forgotten. Someone put the specs in the trash before design was finished. Was a long night again in the design office.
That made me lol, alot
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Posts: 3,010
By: MiG-23MLD
- 24th June 2008 at 21:04Permalink- Edited 1st January 1970 at 01:00
Yes, just forgotten. Someone put the specs in the trash before design was finished. Was a long night again in the design office.
Anyways, a fuel tank in a swept wing comes with price in weight and complexity. It also has a structural knock-on effect, for example on the already highly loaded pivots. So, if your specs don't ask for more range, you cancel that.
It seems general dynamics did not care about riddles and made the F-111 with internal fuel tanks and ability to carry external fuel tanks hanging from the wing pylons.
The Su-24 only carries three external fuel tanks and one is hanging from a fuselage centerline hardpoint and the other two from the wing gloves.
Yefim Gordon only reports the Su-24 has internal fuselage fuel tanks and the cutaway does not show any internal wing fuselage fuel tanks.
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By: MiG-23MLD
- 24th June 2008 at 21:13Permalink- Edited 1st January 1970 at 01:00
Wing internal fuel tanks is OK. The second point is about the landing-gear.
Every technological decision has its price. Another is about external load stations related to VG.
Independently of your riddles it seems you like riddles like the Sphinx, the Sphinx sat outside of Thebes and asked this riddle of all travelers who passed by
What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?
and a modern riddle:
Something "unknown" does beat the Su-24MK by a wide margin, when it does not the F-111 in a similar way. What are the technical secrets of that?
Data from JANE'S
~14,1 tons empty equipped
internal fuel (RAF) 5.090 kg
over 9 tons of external load
over 28 tons MTOW and in overload conditions >30 tons
ferry range > 3900 km
radius of action with heavy weapons-load (hi-lo-lo-hi) 750 nm or 1390 km
Mach 1,2-2,2
You should change it what uses three external fuel tanks, has an engine with a SFC in military power of 0.76 and has only fuselage tanks?
You`ve already gave one before for the Panavia Tornado.
Any way less fuel tanks=less range, SFCs of 0.69 and 0.76 show a slight difference in fuel consumption, the riddle is simple SFC in engine technology does not explain by itself the range difference.
By: Sens
- 24th June 2008 at 21:32Permalink- Edited 1st January 1970 at 01:00
It seems general dynamics did not care about riddles and made the F-111 with internal fuel tanks and ability to carry external fuel tanks hanging from the wing pylons.
The Su-24 only carries three fuel tanks and one is hanging from a fuselage centerline hardpoint and the other two from the wing gloves.
Yefim Gordon only reports the Su-24 has internal fuselage tanks and the cutaway does not show any internal wing fuselage tank.
The only way the range demands could be reached, despite high-tech engines.
Vietnam operation Combat Lancer in 1968 did show, that the F-111A was in need of modification. The main cause came clear by the loss from dec 22 in 1969. The failure of the forged pivot fitting. The Air Force ordered all F-111s grounded, and the plane did not return to service until the following July.
There were still some problems left with the new-tech engine and some electronics including the terrain-following radar. But the F-111 was "over the hill of main problems" now and an excellent striker.
The starting problems of the F-111 were noted by the Russians and they were not eager to repeat that again or learn it the the hard-way, when it came to the related high-tech. Even than it was a long way for the Russians from the Su-24 to the later Su-24MK. Range capability became sacrificial.
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By: MiG-23MLD
- 24th June 2008 at 21:41Permalink- Edited 1st January 1970 at 01:00
The only way the range demands could be reached, despite high-tech engines.
Vietnam operation Combat Lancer in 1968 did show, that the F-111A was in need of modification. The main cause came clear by the loss from dec 22 in 1969. The failure of the forged pivot fitting. The Air Force ordered all F-111s grounded, and the plane did not return to service until the following July.
There were still some problems left with the new-tech engine and some electronics including the terrain-following radar. But the F-111 was "over the hill of main problems" now and an excellent striker.
The starting problems of the F-111 were noted by the Russians and they were not eager to repeat that again or learn it the the hard-way, when it came to the related high-tech. Even than it was a long way for the Russians from the Su-24 to the later Su-24MK. Range capability became sacrificial.
The Russians did indeed want a better engine in the Su-24, they wanted to fit the AL-31 into the Su-24, however it meant a total redesign of its inlets, some Sukhoi designers even proposed a third inlet should had been fitted on top of the fuselage of the Su-24.
At the end it never happened but you overstimate the F-111, the Russians had the Tu-22M and niether Europe or the US designed an aircraft in its class, the Russians never wanted a FB-111 type of aircraft, just a more fuel efficient aircraft by fitting the Al-31, but later they realized the Su-34 was a far better proposition than the F-111 or F-15E type of fighter bomber.
One option never applied onto the Su-24 was applied on the Tu-22M3, the Tupolev bureau did modify the inlets of the original Tu-22M0, this made it a much much better aircraft than the FB-111 and allowed a cheaper more standarized version of Su-24s since the AL-21 was used by other Russian combat aircraft of that time
By: Sens
- 24th June 2008 at 22:16Permalink- Edited 1st January 1970 at 01:00
Sens
Independently of you riddles it seems you like riddles like the Sphinx, the Sphinx sat outside of Thebes and asked this riddle of all travelers who passed by
What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?
and a modern riddle:
Something "unknown" does beat the Su-24MK by a wide margin, when it does not the F-111 in a similar way. What are the technical secrets of that?
Data from JANE'S
~14,1 tons empty equipped
internal fuel (RAF) 5.090 kg
over 9 tons of external load
over 28 tons MTOW and in overload conditions >30 tons
ferry range > 3900 km
radius of action with heavy weapons-load (hi-lo-lo-hi) 750 nm or 1390 km
Mach 1,2-2,2
You should change it what uses three external fuel tanks, has an engine with a SFC in military power of 0.76 and has only fuselage tanks?
You`ve already gave one before for the Panavia Tornado.
Any way less fuel tanks=less range, SFCs of 0.69 and 0.76 show a slight difference in fuel consumption, the riddle is simple SFC in engine technology does not explain by itself the range difference.
At least a nice idea, but that time were better used to compare the related data in an useful manner. For example what is the SFC of the RB.199 or the related fuel ratios.
I am aware, that is no true win situation for the Su-24, because the Russians did reduce the Su-24 in several areas for technical reasons. I am the last one to blame the Russians for that.
In general it shows up as a problem for "blind" or nationalistic supporters.
Nothing uncommon in this forum.
0,69 to 0,76 does look innocent on the first glance, but is a difference of over 10% alone. We keep in mind, that both data do show sweet-points and do say nothing over the consumption behavior over a wider range of power-settings, which are typical during a mission.
Another important point is, that the installed dry thrust is ~40% higher despite similar flight performances. Every kp of thrust has to be fed by fuel.
The secret is related to the air-flow of the TF30. Simplified, the kg/sec output does give something like the torque of a car.
Related to the engines alone, the Su-24 can not win the range contest, when it does come to range of every kg of fuel.
Even with the same amount of fuel, the Su-24 will always be behind in range by 1/3 as a minimum estimate.
By: Sens
- 24th June 2008 at 22:28Permalink- Edited 1st January 1970 at 01:00
The Russians did indeed want a better engine in the Su-24, they wanted to fit the AL-31 into the Su-24, however it meant a total redesign of its inlets, some Sukhoi designers even proposed a third inlet should had been fitted on top of the fuselage of the Su-24.
At the end it never happened but you overstimate the F-111, the Russians had the Tu-22M and niether Europe or the US designed an aircraft in its class, the Russians never wanted a FB-111 type of aircraft, just a more fuel efficient aircraft by fitting the Al-31, but later they realized the Su-34 was a far better proposition than the F-111 or F-15E type of fighter bomber.
One option never applied onto the Su-24 was applied on the Tu-22M3, the Tupolev bureau did modify the inlets of the original Tu-22M0, this made it a much much better aircraft than the FB-111 and allowed a cheaper more standarized version of Su-24s since the AL-21 was used by other Russian combat aircraft of that time
Now you get carried away again.
To make something comparable related to range. You have to look, how many km you can generate from every kg of fuel carried.
Much more reliable than any guessing or strong claims in books.
Another yardstick to make things comparable is the ratio between empty equipped and MTOW. So use your time for the benefit of all and give us some data about that. When I remember well no problem, when it comes to your Russian aircraft books.
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Posts: 3,010
By: MiG-23MLD
- 24th June 2008 at 22:49Permalink- Edited 1st January 1970 at 01:00
Now you get carried away again.
To make something comparable related to range. You have to look, how many km you can generate from every kg of fuel carried.
Much more reliable than any guessing or strong claims in books.
Another yardstick to make things comparable is the ratio between empty equipped and MTOW. So use your time for the benefit of all and give us some data about that. When I remember well no problem, when it comes to your Russian aircraft books.
Yeah you have given a very important aspect see this fact
The TF-30 has less thrust at military power, its SFC at military power is 0.69 kg/kg/h and the F-111 is heavier at MTOW then you have the Su-24, its AL-21 has a SFC at military power of 0.76kg/kg/h it is lighter at MTOW and has a thrust higher at military power.
Then if the F-111 is heavier at takeoff weight since it carries much more fuel, and its cross section is wider, what makes you think its lower yield engines are used more efficiently? you imply that the heavier F-111 has much less drag having even a wider cross section and having heavier MTOWs its lower yield engines will make it fly at the same speed.
is it logic? no it is not logic the F-111 carries more fuel and the AL-21 has a SFC just slightly higher but it has a higher thrust at military power and powers a lighter aircraft, the F-111 achieves more range mostly thanks to a larger fuel capability
see that even if Sukhoi is right the Su-24 carries at the most 21000kg is fuel while the F-111 according to the MTOW cited by the RAAF will carry around 32000kg in fuel and that is almost the same relation in range
By: Sens
- 25th June 2008 at 00:03Permalink- Edited 1st January 1970 at 01:00
Yeah you have given a very important aspect see this fact
The TF-30 has less thrust at military power, its SFC at military power is 0.69 kg/kg/h and the F-111 is heavier at MTOW then you have the Su-24, its AL-21 has a SFC at military power of 0.76kg/kg/h it is lighter at MTOW and has a thrust higher at military power.
Then if the F-111 is heavier at takeoff weight since it carries much more fuel, and its cross section is wider, what makes you think its lower yield engines are used more efficiently? you imply that the heavier F-111 has much less drag having even a wider cross section and having heavier MTOWs its lower yield engines will make it fly at the same speed.
is it logic? no it is not logic the F-111 carries more fuel and the AL-21 has a SFC just slightly higher but it has a higher thrust at military power and powers a lighter aircraft, the F-111 achieves more range mostly thanks to a larger fuel capability
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?
By: Anonymous - 18th June 2008 at 21:25 Permalink - Edited 22nd October 2019 at 22:29
The bulky electronics are probably part of the reason on earlier Fencer variants in particular and the Su-24M has both an interal gun and an internal laser designator installed at the same time. Meanwhile the F-111 carries either one OR the other in its internal bomb bay, optionally foregoing both in favour of more fuel. AFAIK, in practice the bay was rarely used for anything other than those loads, except on the FB-111 where it actually housed weapons (SRAMs).
Not sure how much this eats into the volume available for fuel, but it will have had some effect.
Posts: 3,718
By: Schorsch - 18th June 2008 at 22:01 Permalink - Edited 1st January 1970 at 01:00
The bomb bay was planned as the F-111 was required to make the last 180nm supersonic. It actually never achieved that mark.
For delivering the nuclear bomb a bomb makes sense, for anything else it is not very useful (except for stealthy aircraft).
Fitting a gun into such an aircraft seems doubtful.
As I said, the F-111 was slightly overengineered.
Posts: 3,010
By: MiG-23MLD - 19th June 2008 at 04:37 Permalink - Edited 1st January 1970 at 01:00
In my opinion and i remark it is just an expeculation, the Su-24 has different shape and therefore it does not have the same ability to house fuel tanks.
The Su-24 for example has longer and narrower inlets; the shorter and wider inlets inlets in the F-111 allows in my opinion larger volume capacity fuel tanks since the shorter but wider inlet ducts are not so deeply buried in the fuselage, also the F-111 has bigger wing gloves and contrary to the longer and more deeply buried fuselage inlet ducts that the Su-24 has. the wing gloves can house fuel in the F-111.
Probably this different shape and form account for part of the difference in fuel volume capacity plus the Su-24 is slightly longer and might have heavier avionics
Posts: 3,010
By: MiG-23MLD - 20th June 2008 at 03:35 Permalink - Edited 1st January 1970 at 01:00
An early Su-24 might look like it had a wider gap between the engine nacelles
however in this picture is clear the F-111 has a wider gap between the engine nacelles
In the same way in this picture it is clear the Su-24 has a narrower fuselage and a narrower engine gap with each other see
http://www.n-e-c.ru/foxbat/maks/kiev_museum/index.php?picid=kiev_museum102
This explain easily why the F-111 has more volume capacity, the fuselage tanks are bigger in the F-111
Posts: 620
By: franc - 21st June 2008 at 14:09 Permalink - Edited 1st January 1970 at 01:00
How large the fuselage is not only depands on the gap between the engine nacelles but also depands on the size of engine. meanwhile,
how many fuel the fuselage carry not only depands on the size of fuselage but also the size of engine.
Posts: 3,010
By: MiG-23MLD - 23rd June 2008 at 04:44 Permalink - Edited 1st January 1970 at 01:00
The TF-30 and Al-21 are almost the same size and ironically, the TF-30 is slightly bigger, however it is obvious the Su-24 has a slimmer fuselage and smaller wing gloves, and in general dimensions is slightly larger, that is the only way to explain the smaller fuel capacity it has.
Posts: 11,742
By: Sens - 23rd June 2008 at 17:56 Permalink - Edited 1st January 1970 at 01:00
Good finding. Look into the cutaways of both aircrafts and you will find out, where that "extra" fuel is housed.
Posts: 3,010
By: MiG-23MLD - 24th June 2008 at 01:44 Permalink - Edited 1st January 1970 at 01:00
independently of the riddle, the Su-24 has only fuselage fuel tanks and the F-111 has wing internal fuel tanks, however the Su-24 has narrower fuselage.
Posts: 11,742
By: Sens - 24th June 2008 at 15:59 Permalink - Edited 1st January 1970 at 01:00
Wing internal fuel tanks is OK. The second point is about the landing-gear.
Every technological decision has its price. Another is about external load stations related to VG.
http://www.globalsecurity.org/military/systems/aircraft/images/f-111f-DF-ST-91-02452.jpg
http://www.aeronautics.ru/sukhoi/su-24_fencer/su-24m-022-ukraine.jpg
http://images.google.de/imgres?imgurl=http://www.aeronautics.ru/sukhoi/su-24_fencer/su-24-diagram-004.jpg&imgrefurl=http://www.aeronautics.ru/sukhoi/su-24_fencer/page_03.htm&h=1171&w=1800&sz=587&hl=de&start=24&tbnid=6O1r5DZBapre0M:&tbnh=98&tbnw=150&prev=/images%3Fq%3DSu-24%26start%3D20%26gbv%3D2%26ndsp%3D20%26hl%3Dde%26client%3Dfirefox-a%26rls%3Dorg.mozilla:de:official%26sa%3DN
http://www.aeronautics.ru/sukhoi/su-24_fencer/su-24m-010.jpg
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By: franc - 24th June 2008 at 16:41 Permalink - Edited 1st January 1970 at 01:00
Why there is no fuel tank in Su-24's wing? forgot?
Posts: 3,718
By: Schorsch - 24th June 2008 at 20:37 Permalink - Edited 1st January 1970 at 01:00
Yes, just forgotten. Someone put the specs in the trash before design was finished. Was a long night again in the design office.
Anyways, a fuel tank in a swept wing comes with price in weight and complexity. It also has a structural knock-on effect, for example on the already highly loaded pivots. So, if your specs don't ask for more range, you cancel that.
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By: Jon James - 24th June 2008 at 20:39 Permalink - Edited 1st January 1970 at 01:00
That made me lol, alot
Posts: 3,010
By: MiG-23MLD - 24th June 2008 at 21:04 Permalink - Edited 1st January 1970 at 01:00
It seems general dynamics did not care about riddles and made the F-111 with internal fuel tanks and ability to carry external fuel tanks hanging from the wing pylons.
The Su-24 only carries three external fuel tanks and one is hanging from a fuselage centerline hardpoint and the other two from the wing gloves.
Yefim Gordon only reports the Su-24 has internal fuselage fuel tanks and the cutaway does not show any internal wing fuselage fuel tanks.
Posts: 3,010
By: MiG-23MLD - 24th June 2008 at 21:13 Permalink - Edited 1st January 1970 at 01:00
Sens
Independently of your riddles it seems you like riddles like the Sphinx, the Sphinx sat outside of Thebes and asked this riddle of all travelers who passed by
What goes on four legs in the morning, on two legs at noon, and on three legs in the evening?
and a modern riddle:
Something "unknown" does beat the Su-24MK by a wide margin, when it does not the F-111 in a similar way. What are the technical secrets of that?
Data from JANE'S
~14,1 tons empty equipped
internal fuel (RAF) 5.090 kg
over 9 tons of external load
over 28 tons MTOW and in overload conditions >30 tons
ferry range > 3900 km
radius of action with heavy weapons-load (hi-lo-lo-hi) 750 nm or 1390 km
Mach 1,2-2,2
You should change it what uses three external fuel tanks, has an engine with a SFC in military power of 0.76 and has only fuselage tanks?
You`ve already gave one before for the Panavia Tornado.
Any way less fuel tanks=less range, SFCs of 0.69 and 0.76 show a slight difference in fuel consumption, the riddle is simple SFC in engine technology does not explain by itself the range difference.
Posts: 11,742
By: Sens - 24th June 2008 at 21:32 Permalink - Edited 1st January 1970 at 01:00
The only way the range demands could be reached, despite high-tech engines.
Vietnam operation Combat Lancer in 1968 did show, that the F-111A was in need of modification. The main cause came clear by the loss from dec 22 in 1969. The failure of the forged pivot fitting. The Air Force ordered all F-111s grounded, and the plane did not return to service until the following July.
There were still some problems left with the new-tech engine and some electronics including the terrain-following radar. But the F-111 was "over the hill of main problems" now and an excellent striker.
The starting problems of the F-111 were noted by the Russians and they were not eager to repeat that again or learn it the the hard-way, when it came to the related high-tech. Even than it was a long way for the Russians from the Su-24 to the later Su-24MK. Range capability became sacrificial.
Posts: 3,010
By: MiG-23MLD - 24th June 2008 at 21:41 Permalink - Edited 1st January 1970 at 01:00
The Russians did indeed want a better engine in the Su-24, they wanted to fit the AL-31 into the Su-24, however it meant a total redesign of its inlets, some Sukhoi designers even proposed a third inlet should had been fitted on top of the fuselage of the Su-24.
At the end it never happened but you overstimate the F-111, the Russians had the Tu-22M and niether Europe or the US designed an aircraft in its class, the Russians never wanted a FB-111 type of aircraft, just a more fuel efficient aircraft by fitting the Al-31, but later they realized the Su-34 was a far better proposition than the F-111 or F-15E type of fighter bomber.
One option never applied onto the Su-24 was applied on the Tu-22M3, the Tupolev bureau did modify the inlets of the original Tu-22M0, this made it a much much better aircraft than the FB-111 and allowed a cheaper more standarized version of Su-24s since the AL-21 was used by other Russian combat aircraft of that time
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By: Sens - 24th June 2008 at 22:16 Permalink - Edited 1st January 1970 at 01:00
At least a nice idea, but that time were better used to compare the related data in an useful manner. For example what is the SFC of the RB.199 or the related fuel ratios.
I am aware, that is no true win situation for the Su-24, because the Russians did reduce the Su-24 in several areas for technical reasons. I am the last one to blame the Russians for that.
In general it shows up as a problem for "blind" or nationalistic supporters.
Nothing uncommon in this forum.
http://momox.org/sphinx.html
0,69 to 0,76 does look innocent on the first glance, but is a difference of over 10% alone. We keep in mind, that both data do show sweet-points and do say nothing over the consumption behavior over a wider range of power-settings, which are typical during a mission.
Another important point is, that the installed dry thrust is ~40% higher despite similar flight performances. Every kp of thrust has to be fed by fuel.
The secret is related to the air-flow of the TF30. Simplified, the kg/sec output does give something like the torque of a car.
Related to the engines alone, the Su-24 can not win the range contest, when it does come to range of every kg of fuel.
Even with the same amount of fuel, the Su-24 will always be behind in range by 1/3 as a minimum estimate.
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By: Sens - 24th June 2008 at 22:28 Permalink - Edited 1st January 1970 at 01:00
Now you get carried away again.
To make something comparable related to range. You have to look, how many km you can generate from every kg of fuel carried.
Much more reliable than any guessing or strong claims in books.
Another yardstick to make things comparable is the ratio between empty equipped and MTOW. So use your time for the benefit of all and give us some data about that. When I remember well no problem, when it comes to your Russian aircraft books.
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By: MiG-23MLD - 24th June 2008 at 22:49 Permalink - Edited 1st January 1970 at 01:00
Yeah you have given a very important aspect see this fact
The TF-30 has less thrust at military power, its SFC at military power is 0.69 kg/kg/h and the F-111 is heavier at MTOW then you have the Su-24, its AL-21 has a SFC at military power of 0.76kg/kg/h it is lighter at MTOW and has a thrust higher at military power.
Then if the F-111 is heavier at takeoff weight since it carries much more fuel, and its cross section is wider, what makes you think its lower yield engines are used more efficiently? you imply that the heavier F-111 has much less drag having even a wider cross section and having heavier MTOWs its lower yield engines will make it fly at the same speed.
is it logic? no it is not logic the F-111 carries more fuel and the AL-21 has a SFC just slightly higher but it has a higher thrust at military power and powers a lighter aircraft, the F-111 achieves more range mostly thanks to a larger fuel capability
see that even if Sukhoi is right the Su-24 carries at the most 21000kg is fuel while the F-111 according to the MTOW cited by the RAAF will carry around 32000kg in fuel and that is almost the same relation in range
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By: Sens - 25th June 2008 at 00:03 Permalink - 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?