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Fighter aircraft engine comparision

Posted by picard578 on December 6, 2014

Introduction

This article will compare several engines used in modern fighter aircraft: EJ200 (Typhoon), M88 (Rafale B/C/M), RM-12 (Gripen A/B/C/D), F-135 (F-35A/B/C), F-119 (F-22A), F404-GE-402 (F-18C/D), F-414-400 (F-18E/F, Gripen E/F), AL-31F (Su-27, Su-30, J-11).

Thrust to drag

Since frontal area dominates drag, and engine frontal area dominates aircraft frontal area, thrust to drag ratio will take a form of thrust divided by the engine frontal area (inlet diameter used).

EJ200: 3.848 cm2, 90 kN, 23,13 N/cm2

M88-2: 3.805 cm2, 73,9 kN, 19,42 N/cm2

RM-12: 3.948 cm2, 80,5 kN, 20,39 N/cm2

F-135 (CTOL): 10.715 cm2, 191,35 kN, 17,86 N/cm2

F-135 (STOL): 10.715 cm2, 182,4 kN, 17,02 N/cm2

F-119: 6.136 cm2, 164,58 kN, 26,82 N/cm2

F404-GE-402: 3.959 cm2, 78,7 kN, 19,88 N/cm2

F-414-400: 4.745 cm2, 97,37 kN, 20,52 N/cm2

AL-31F: 6.433 cm2, 122,58 kN, 19,05 N/cm2

AL-41F: 6.433 cm2, 175 kN, 27,2 N/cm2

As it can be seen, EJ200 has the second best thrust-to-drag ratio after the F-119, while the F-135 has the lowest thrust-to-drag ratio. EJ230 has a ratio of 26,9 N/cm2, while the F-414EPE will have a ratio of 24,62 N/cm2. M-88ECO will have a ratio of 23,65 N/cm2.

(This is one of reasons why single engined fighters typically have better peformance than twin engined fighters despite lower thrust-to-weight ratio. Engine frontal area is one of major contributors to drag in all “normal” flight conditions. Taking two engines that use same technology and general design, frontal area – and drag – will increase with square of dimensions’ increase, while weight – and thus thrust – will increase with cube of dimensions’ increase. Engine that is 20% larger in all three dimensions will have 44% greater frontal area and 72,8% more weight and thrust – thus its thrust-to-drag ratio will be 20% greater than that of the smaller engine. If engines are of the same size and characteristics, then twin engined aircraft will be larger and have higher inertia and inferior transient performance. This of course assumes identical design goals and avaliable technology. For example, F-119 is 239% larger in volume than the EJ200, has 59% greater frontal area and 15% better thrust-to-drag ratio.).

NOTE: M88-2 has been tested at 18.700 lbf in 1990, which would give it 21,86 N/cm2.

Thrust to weight

Engine thrust to weight ratio is an important (though not the only) factor in determining aircraft’s thrust-to-weight ratios, just as engine’s thrust-to-drag ratio is an important factor in determining aircraft’s thrust-to-drag ratio.

EJ200: 2.180 lbs, 20.250 lbf, 9,17:1

M88-2: 1.977,5 lbs, 16.620 lbf, 8,40:1

RM-12: 2.326 lbs, 18.100 lbf, 7,78:1

F-135 (CTOL): 6.444 lbs, 43.000 lbf, 6,67:1

F-135 (STOL): 10.342 lbs, 41.000 lbf, 3.96:1

F-119: 3.900 lbs, 37.000 lbf, 9,49:1

F404-GE-402: 2.282 lbs, 17.700 lbf, 7,76:1

F414-400: 2.445 lbs, 21.890 lbf, 8,95:1

AL-31F: 3.460 lbs, 27.560 lbf, 7,97:1

AL-41F: 1.850 kg, 17.845 kgf, 9,65:1

EJ230 has a thrust-to-weight ratio of 10,60:1 and F-414EPE will have a thrust-to-weight ratio of 10,74:1. M-88ECO will have a ratio of 9,32:1.

NOTE: F-135 weights were provided by Bill Sweetman here (comments section), citing Erin Dick. They are also listed here.

NOTE 2: M88-2 has been tested at 18.700 lbf in 1990. This would give it a TWR of 9,17.

Fuel consumption

Fuel consumption depends on both thrust and thrust-specific fuel consumption. Since aircraft with higher TWR can reduce thrust and still match performance of lower-TWR aircraft, both thrust-specific and total fuel consumption, at dry thrust and afterburner, will be compared.

Dry thrust:

EJ200: 21-23 g/kN s, 60 kN = 4.536-4.968 kg/h

M88-2: 0,8 kg/daN h, 48,8 kN = 3.904 kg/h

RM-12: 23,9 g/kN s, 54 kN = 4.646 kg/h

F-135: 0,89 kg/daN h, 124,6 kN = 11.089 kg/h

F-119: N/A (est: 0,8 kg/daN h, 116 kN = 9.968 kg/h)

F404-GE-402: 82,6 kg/kN h = 4.039 kg/h

F414-400: 0,84 kg/daN h, 57,8 kN = 4.855 kg/h

AL-31F: 0,87 kg/kgf*h, 7.575 kgf (74,5 kN) = 6.590 kg/h

AL-41F: 19,18 g/kN s, 113,9 kN = 7.865 kg/h

EJ200 consumes 82,8 kg/kN h, M88-2 consumes 80 kg/kN h, RM-12 consumes 86 kg/kN h, F-119 consumes 80 kg/kN h, F404-GE-402 consumes 83 kg/kN h, and F414-400 consumes 84 kg/kN h. F-135 is not capable of supercruise, but for completeness’ sake it does consume 89 kg/kN h. AL-31 consumes 88,5 kg/kN h and AL-41 consumes 69 kg/kN h.

Afterburner:

EJ200: 47-49 g/kN s, 90 kN = 15.228-15.876 kg/h

M88-2: 1,7 kg/daN h, 73,9 kN = 12.563 kg/h

RM-12: 50,6 g/kN s, 80,5 kN = 14.664 kg/h

F-135: 1,92 kg/daN h, 191,35 kN = 36.739 kg/h

F-119: N/A (est: 1,85 kg/daN h, 164,58 kN = 30.447 kg/h)

F404-GE-402: 177,5 kg/kN h, 78,7 kN = 13.969 kg/h

F414-400: 1,85 kg/daN h, 97,9 kN = 18.112 kg/h

AL-31F: 1,92 kg/kgf*h, 12.501 kgf (122,58 kN) = 24.002 kg/h

AL-41F: 54,11 g/kN s, 175 kN = 34.089 kg/h

Neither EJ230 or M88ECO offer improved SFC over basic variants. F414EDE/EPE could reduce SFC to 0,81 kg/daN h and 1,78 kg/daN h, comparable to the M88.

In the afterburner, EJ200 consumes 169,2-176,4 kg/kN h, M88-2 consumes 170 kg/kN h, RM-12 consumes 182 kg/kN h, F-135 consumes 192 kg/kN h, F-119 consumes 185 kg/kN h, F404-GE-402 consumes 177,5 kg/kN h, F414-400 consumes 185 kg/kN h, AL-31 consumes 195,8 kg/kN h and AL-41F consumes 194,8 kg/kN h.

Overall, M88 is the most fuel-efficient engine, followed by the EJ200 and F119, though all are less fuel efficient than AL-41 at subsonic regime. AL-31 is the least fuel-efficient engine.

Bypass ratio

Main function of low bypass ratio is to enable the engine to achieve high thrust-to-weight and thrust-to-drag ratio at dry thrust; both these qualities are required for supercruise.

EJ200: 0,4:1

M88-2: 0,3:1

RM-12: 0,31:1

F-135: 0,57:1

F-119: 0,3:1

F404-GE-402: 0,34:1

F414-400: 0,25:1

AL-31F: 0,59:1

AL-41F: 0,59:1

M88-2 has, interestingly enough, lower bypass ratio than the EJ200, indicating greater focus on supersonic performance. F-135 is quite obviously optimized for subsonic/transonic performance, and combined with unaerodynamic airframe (too fat for proper area ruling) and engine’s own low thrust-to-drag ratio, it is unrealistic to expect the F-35 to achieve any kind of sustained supersonic cruise. AL-31 is also optimized for subsonic-supersonic performance, but is paired to the far superior airframe. F-414 is the closest to being a turbojet out of all engines listed.

Percentage of maximum thrust achievable on dry power:

EJ200: 67%

M88-2: 66%

RM-12: 67%

F-135: 65%

F-119: 70%

F404-GE-402: 62%

F414-400: 69%

AL-31F: 61%

AL-41F: 65%

F-119 is the best while most other engines trail very closely behind it. AL-31 is the worst, and the F404 is the second worst.

Mechanical reliability and maintainability

Mechanical reliability depends in part on mechanical complexity. While most engines use the same basic architecture, there are things they very clearly differ in.

EJ200 has 8 compressor and 2 turbine stages

M88 has 9 compressor and 2 turbine stages

RM-12 has 10 compressor and 2 turbine stages

F-135 has 9 compressor and 3 turbine stages

F-119 has 9 compressor and 2 turbine stages

F404-GE-402 has 10 compressor and 2 turbine stages

F414-400 has 10 compressor and 2 turbine stages

AL-31F has 13 compressor and 2 turbine stages

AL-41F has 13 compressor and 2 turbine stages

While this is a vast oversimplification, going by number of stages alone, EJ200 would be the most reliable and easiest to maintan, while AL-31 would be the least reliable. EJ200 also has the fewest 1st stage fan blades of any modern fighter aircraft engine. F-119 has an additional failure point in form of the thrust vectoring nozzle, and the F-135 variant used on the F-35B has two additional failure points – TVC nozzle and a lift fan, plus a third failure point in form of doors for the lift fan which techically are not part of the engine. In the F-135s case, several weight reduction measures also made it far more vulnerable to the combat damage.

Many of these engines also use modular design to simplify maintenance. Number of modules is as follows:

EJ200: 15

M88: 21

RM-12: 6

F-135: 5

F-119: 4

F404-GE-402: 6

F-414-400: 6

As it can be seen, M88 and EJ200 would be easiest to maintain, especially the M88.

Service life is as follows:

EJ200: 6.000 h

M88: ??

RM-12: 4.000 h

F-135: 2.000 h

F119: 6.000 h (?)

F404-GE-402: 4.000 h

F414-400: 6.000 h

AL-31F: 1.500 h

AL-41F: 4.000 h

Overall, EJ200 is the most user-friendly engine.

IR signature

Engine inlet temperature can be used to approximate IR signature when combined with thrust. It is not a perfect measure as there are other factors influencing IR signature as well.

EJ200: >1.800 K, 20.250 lbf

M88: 1.850 K, 16.620 lbf

RM-12: >1.717 K, 18.100 lbf

F-135: 2.255 K, 43.000 lbf

F-119: ?, 37.000 lbf

F404-GE-402: 1.717 K, 17.700 lbf

F414-400: ?, 21.890 lbf

AL-31F: 1.685 K, 27.560 lbf

AL-41F: 1.887 K, 39.340 lbf

M88 has an additional cooling channel beyond one typically present, as well as second set of nozzles which partly hide the afterburning plume and inner nozzle. F-119s nozzles, meant to reduce RCS, also reduce IR signature of the exhaust plume by increasing its area/volume ratio. F-135 on the other hand has relatively thin skin, and the F-35 is thin-skinned itself, thus increasing IR signature. EJ200 is another engine that had its skin thinned in order to save weight.

Combination of thin skin, high thrust and very high inlet temperature means that the F-135 has the highest IR signature, while the M88 has the lowest IR signature due to low thrust and IR signature supression measures; F404 should have the second lowest IR signature. Further, higher operating temperature means greater stress on components and thus more frequent maintenance, other things being equal.

Conclusion

Overall, the F-119 is the best engine where performance is concerned, followed rather closely by the EJ200 and F-414-400. EJ-230 is better than the F-119. RM-12 is the second worst and F-135 is the worst Western engine while the AL-31F is the worst engine overall (not surprising considering its age; AL-41F does match modern Western fighter engines in at least some performance parameters, but at cost of the service life).

All problems with the F-135 are connected to the fact that the F-35 is a strike fighter by design, and not a proper multirole fighter; on the other hand, EJ200, M88 and the F-119 are designed for fighter aircraft whose primary role is air superiority. As a result, F-135 is optimized for different operational conditions and regimes compared to other engines listed here, and it is unrealistic to expect the F-35 to achieve even marginal supercruise performance. On the other hand, it can be seen from the article, and notes below, that the F-119s advantages stem mainly from its large size.

That being said, pure performance is not the only important factor. Just as important, if not more so, are reliability and ease of maintenance in the field. EJ200 is likely the most reliable engine, while the M88 is easiest to maintain. When all factors are taken into account, EJ200 would be the best choice for a fighter aircraft – assuming that thrust is sufficient, of course.

Notes

Turbojet J85-GE-21 with 5.000 lbf / 22 kN / 2.243 kgf of afterburning thrust would have a thrust-to-weight ratio of 11,74 and thrust-to-drag ratio of 13,84 N/cm2. J97-GE-100 has 8.000 lbf / 35 kN /3.629 kgf has a thrust-to-weight ratio of 11,5:1 and thrust-to-drag ratio of 14,27 N/cm2. Low thrust-to-drag ratio despite these engines’ high thrust-to-weight ratio and lower frontal area than that of the comparable turbofan can only be explained by their small size, confirming the conclusion about single vs twin engines from first section of the article. For comparision, J79-GE-17 turbojet (J97 was/is used on the F-104, F-5, F11F-1F, IAI Kfir, A-5 and F-16/79) has 17.835 lbf / 79,3 kN / 8.090 of afterburning thrust, thrust-to-weight ratio of 4,6:1 (40% of the J97-GE-100) but thrust-to-drag ratio of 10,67 N/cm2 (75% of the J97-GE-100).

If the F119 is reduced to the EJ200s size, it would be 4 meters long and 93 cm in diameter, compared to 74 cm for the EJ200. Inlet diameter would be 68,5 cm, dry weight ~1.000 kg, and thrust 91,4 kN (9.320 kgf). Thus it would have a TWR of ~9,32:1 and thrust-to-drag ratio of 24,8 N/cm2, or 92% of the current value, again confirming that larger engine offers better performance than two smaller engines.

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90 Responses to “Fighter aircraft engine comparision”

  1. Looping said

    It could be intresting to have some Russian engine (Saturn AL-31 or some others) in this type of comparaison.
    Saturn AL-31 :

    Also, the number of cycles (from zero to full to zero) for the lifespan (M88-4E : 4000 cycles) or its translation in flight hours.

    ( http://air-defense.net/journal/book/m88-vs-ej-200 some data, sorry it’s in French)

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  2. MarkyMark said

    Why not include the GE F404? The RM12, which powers the Gripen, is a derivative of the engine. Why not include the F404? It’s a reliable, powerful engine; as such, it should be on your list.

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  3. Andrei said

    Service life of F-135 despite it’s stated goal of 6000 h is at the moment a little over 2000h since it’s failure on the benchmark. Failure which seems to be a design flaw.
    Also the 800h service life of M-88 seems a little on the small size for a modern engine are you sure you didn’t forget a zero as in 8000h?

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  4. Chris said

    What I find astonishing about this is that despite the massive advancements compared to the 1950s jet engines, it seems that fighter aircraft in many regards have not made the quantum leaps in performance that one would expect compared to say, civil aviation. Fuel fraction has not radically gone up, cruise speed has only recently gone up in the so called “4.5” and “5th generation” fighters, and a lot of other performance metrics have not made the expected leaps. This despite improvements in aerodynamics, materials sciences, and elsewhere too.

    Compare say, a Boeing 707 with a 787 or Airbus A350 and note the technological advancements.

    That being said, pure performance is not the only important factor. Just as important, if not more so, are reliability and ease of maintenance in the field. EJ200 is likely the most reliable engine, while the M88 is easiest to maintain. When all factors are taken into account, EJ200 would be the best choice for a fighter aircraft – assuming that thrust is sufficient, of course.

    The other issue being of course that the F119, even were it made for a single fighter would be simply too large (therefore expensive) to make a good dedicated fighter.

    Perhaps as you note if an F119 was shrunk it’d be interesting to compare.

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    • picard578 said

      “This despite improvements in aerodynamics, materials sciences, and elsewhere too.”

      It’s mostly due to focus on technological as opposed to tactical definition of capability. A.K.A. “what gadgets aircraft has” as opposed to “what it can achieve in combat”. Good readings here:
      http://www.airpower.maxwell.af.mil/airchronicles/aureview/1983/sep-oct/lind.html
      http://pogoarchives.org/labyrinth/11/12.pdf

      http://pogoarchives.org/labyrinth/09/08.pdf
      https://defenseissues.wordpress.com/2014/01/04/quality-versus-quantity-fallacy/

      “The other issue being of course that the F119, even were it made for a single fighter would be simply too large (therefore expensive) to make a good dedicated fighter.”

      Not really. F119 is 5,16 m long and 1,2 m in diameter. J79 (used on F-16/79 and F-104) is 5,3 m long and 1,0 m in diameter. F100 (used on the YF-16 and F-16) is 4,9 m long and 1,2 m in diameter. M53 (used in Mirage) is 5,1 m long and 0,8 m in diameter. As you can see, F119 is almost the same size as the F100, only a bit longer, and it would be shorter if TVC nozzle was to be removed.

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      • Andrei said

        I wonder how the F-35 would have looked like had it been sized for the F 119. I mean the thrust difference is not that big compared to the weight and drag increases the the F 135 brings. Besides seeing as the F-35 was initially supposed to be the low end of the high-low mix of which the F-22 was the high end would it not have been logical for them tho share the same engine to reduce maintenance costs?

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        • picard578 said

          It would have been a far better option – kind of like the F-15 and the F-16 – but it was impossible given the requirements. F119 was not powerful enough to provide the STOVL capability needed. Had the F-35 simply been a “stealth F-16”, then yes, the F119 would have been a far better option.

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      • Andrei said

        Or they could have gone with the fan in wing option that was tested successfully on the Ryan XV5 in the 50s and 60s and later abandoned because the project was financed by the Army not the Air Force. I’ll put the link to the Wikipedia page again: https://en.wikipedia.org/wiki/Ryan_XV-5_Vertifan (yes I like this design very much)
        The Vertifan could take-off and land vertically despite having only jet engines that gave it a thrust to weight ration of bellow 0.5, because for vertical lift the thrust of the jet engines was diverted to spin the fans in the wings and nose which for that flight profile produced more then 3 times the thrust of the jet-engines and allowed the XV-5 to be a true VTOL aircraft. And the system was also very fuel efficient the XV-5 could hover for prolonged times and thus was even tested as SAR aircraft. Further more it could land vertically one only one engine, which was the reason the F-35 was made with only one engine. The solutions used on the JSF could not ensure enough thrust to land with only half of available thrust (one engine out scenario) so the requirement was made for single engine aircraft.
        Just imagine with the fan in wing design and the large diamond wing of the F-22, maybe the JSF could have been a VTOL variant of the F-22. So there could have been an F-22 A like the standard for the USAF for the air-superiority mission, an F-22B VTOL with armored protection for the engines and pilot with less maneuverability for the USAF, USMC and USN to use for ground attack and CAS and an F-22C for CATOBAR operations do be used by the Navy for fleet defense. With that many variants maybe the price of the F-22 could have been brought down to F-16 like levels. Who knows?

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        • picard578 said

          I mostly agree, except:
          1) even F-22s VTOL aircraft would be useless for CAS, as VTOL nature would by itself likely preculde carriage of heavy armor. Let alone a 30 mm Gattling gun.
          2) Aircraft’s price is partly dependant on weight, partly on complexity of aircraft itself, and partly on efficiency of the production process. Only last one improves with time, so it is impossible for the F-22 to have ever matched the F-16 in price.

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      • Andrei said

        Just for the sake of argument I have to give my two cents 😀 :
        1) Yes but maybe they could have come up with something like internal mounting of the GAU 13 (30mm four barrels) which is lighter then the GAU 8 (30mm 7 barrels). And some sort of Armour/fuel modules which would have field all 3 missiles bays and would thus have protected the engines as the internal missile bays are placed around the engines. Maybe the bay doors could have been removed in this configuration and so the modules could have protruded to the rear so that their amour would completely cover the engines, and could also have had hard-points to carry Mavericks, as Stealth would be pointless for CAS and F/A2-22B would use its EW suite more . Fuel would have been used first from the modules so that once over the FEBA they would have been empty and capable to take hits. So for CAS the F/A-22 B would have been fitted only with the modules and the gun and Mavericks and even if over weight it could have used the fans for short take-off, and also it could have used the fans to operate safely bellow stall speed and thus fly slow enough to pick out targets. For normal ground attack (interdiction or whatever) it would not have carried Armour modules, would have decreased ammo for the gun and would have used the bays for whatever ordinance was needed.
        2) For decreasing price maybe with 3 variants they could have tailored the avionics and sensors suits better for example F/A-22B would not have carried radar to make room for gun in nose and would have replaced that with an IRST – FLIR combo that would have been much better for CAS/Ground attack and would have also aided in self-defense against aircraft. The radar is the single most expensive piece of hardware on the F-22 after the engines. Further more for F-22A and C if they would have insisted on radar they could have gone with a more simple radar suitable only for air-to-air engagements. Further reduction in price could have come from simply sizing the bays just for Air-to-Air missiles on the F-22A/C and by making them capable of only using air-to-air weapons, and putting JADAMs and SDBs and other ground ordinance only on the F/A-22B which would be able to use only Sidewinders as air-to-air weapons. Thus the complexity of individual variants could have been decreased not like they do now to the F-35, in which every variant has to be able to do everything.

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        • picard578 said

          All of that is possible, but armor modules can never give as good protection as inbuilt armor, and fact remains that the F-22 does not have internal 30 mm cannon (and cannot mount one either, at least not of the kind required for CAS), and is too expensive and complex to provide meaningful force presence. Plus its unsuitable aerodynamics (thin, swept wings in particular) will heavily limit both low speed maneuverability and endurance. F-15E is useless for CAS for mostly similar reasons.

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    • Chris said

      Oops my bad – I had thought that the F119 had been a larger engine. Should have looked at the dimensions. Brain freeze I suppose.

      Hmm … I wonder. If an F119 had been made without TV and made for an FLX-like aircraft versus an M88 or EJ200, how would it fare? On one hand, complexity might favor the other two engines. On the other hand, the advantages of the F-119 may favor performance.

      As said, I’ve wondered whether a dedicated turbojet would be a better choice. The reason is that historically, jets only touched supersonic for a brief period in their lives, so I guess turbofans with higher bypass ratios made sense. But with an aircraft that is designed to spend most of its life as supersonic (perhaps the only other example is the Concorde), that changes everything and a turbojet becomes a much more attractive option. That and it might be more mechanically simple.

      The trend is clear though – engine inlet temperature continues to rise over time.

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      • picard578 said

        “If an F119 had been made without TV and made for an FLX-like aircraft versus an M88 or EJ200, how would it fare?”

        Having F119 would favor cruise speed and acceleration due to its massive thrust and high thrust-to-drag ratio. On the other hand, having a larger engine would result in a larger aircraft, thus increasing cost, increasing visual and IR signatures and harming portions of transient performance. That is one reasons why I opted for the EJ230 in the end – M88 could allow even smaller fighter while F119 would offer better performance, but in the end EJ230 was an optimal balance between thrust and size (for the record, I judged F-16s F110 as being too large as I aimed at something around RM12s size, and F119 is larger still). Second reason is that I didn’t want a thrust-vectoring nozzle, and F119 isn’t avaliable without it.

        In the end, TWR of 1,25 at combat weight is perfectly acceptable, especially for an aircraft with so high fuel fraction. You want even higher TWR? Dump some fuel to reduce fuel fraction to 0,15 and weight to 7.284 kg, and watch TWR jump from 1,25 to 1,44. Oh, and in such situation TWR at *dry* thrust would be 1,01. Even a baseline EJ200 would give a TWR of 1,26 in such configuration.

        “As said, I’ve wondered whether a dedicated turbojet would be a better choice.”

        Probably, but no new turbojets are avaliable.

        “That and it might be more mechanically simple.”

        It IS more mechanically simple. You see, every single turbofan engine is basically a turbojet with additions – turbojet forms turbofan’s core, only difference is that in turbojet the entire air flow goes through the core, meaning that there is no need for bypass. This results in higher dry thrust and better supersonic thrust-to-drag ratios for a given tech level, plus less complexity. End result is that, for the same tech level, turbojet can achieve 20-30% greater thrust-to-weight ratio while costing 25-40% as much as a turbofan.

        “The trend is clear though – engine inlet temperature continues to rise over time.”

        That is unavoidable, though, as it results in better efficiency (assuming all other factors are equal).

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    • picard578 said

      I’m now thinking about designing a point defense interceptor around the F119. It would be a tailless canardless delta, something like the F-106 or Mirage III.

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      • Andrei said

        “I’m now thinking about designing a point defense interceptor around the F119. It would be a tailless canardless delta, something like the F-106 or Mirage III.”

        How about an F-16XL with the F119 engine. You read Design for Air Combat which gives a very good description of the advantages of the Double Delta F-16 compared to standard especially in regards to supersonic maneuverability and cruise (what one wants most for an interceptor)

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      • Mike said

        How about merely modernising the F104 around an M88?

        The 88 has roughly comparable performance to the J79 hence the significant size reduction should give a very interesting perspective on what could be done by merely simplifying an aircraft’s role.

        No multi-role, merely a 60k+ mach 2 man in a missile. Call it an F35 killer for export. Could even give it the same AA loadout and weaknesses ( no rearward visibility etc) to see how light and cheap a dedicated airframe could fulfil that aspect.

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        • picard578 said

          That would be good, but you have to take into account that turbofan engines tend to be far more expensive than turbojets. So it shouldn’t be done without cost-benefit analysis being done first (something that US *never* do).

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      • Mike said

        “That would be good, but you have to take into account that turbofan engines tend to be far more expensive than turbojets.”

        I don’t know of a turbojet of similar performance in production. A turbojet would be ideal though.

        It strikes me that the many problems which plagued the F104 could be overcome with more modern tech. At the end of the day the design sold more than 2500 copies, with the vast majority going for export.

        An updated F-106 would be an interesting read, though somewhat US specific.

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  5. stormshadow said

    Picard what do you think of the thermoreactor. It would allow far better TWR than turbojet while being much simpler and thrust to drag ratio and specific thrust similar to rocket engine so much better than turbojet while being far more efficient because of much higher compression ratio.

    http://www.xplorair.com/thermoreactor.html

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    • picard578 said

      Sounds OK, but I can’t really comment.

      Like

      • Andrei said

        Not I good idea without nano-technology. Squeezing that thing in the wing will be impossible without increasing wing thickness. And also it suggests using a paddle-wheal for powering the compressor stage instead of a turbine. There is a reason paddle-wheal lost to propellers they are much less efficient. And in the air which is a much less thicker fluid that gap in efficiency increases.
        But once the components can be miniaturized enough down to the micro level maybe even the nano level for the paddles the whole system might become very efficient.

        Like

  6. Dear Picard578,

    In the excellent “Comparing a Quarter Century of Figthers”, Mr. Pierre Sprey suggest a F-5E with 20% less weight.
    What would you suggest to achieve such weight reduction in the Tiger II ?

    Like

    • Andrei said

      Picards FLX is basically an F-5E with 20% less weight. There are six iterations of it. Personally I like the ones with 10 m length (I think version 3 and 4), not the latest. But that’s just me 😀

      Like

      • Dear Andrei,

        I mean specifically in the F-5 model `E`.
        Indeed, I can not see how, perhaps no radar or a lighter one, structure or less gun ammo.

        Like

      • picard578 said

        Issue is, only the latest FLX version could be produced as-is, with end specifications about same as in my proposal. All other versions would see significant increases in size and weight, which would nullify any theoretical advantages over the last version.

        Like

    • picard578 said

      1) Replace two M39A2 (2*81 kg) with a single GIAT 30 (120 kg). Weight loss: 42 kg.
      2) Replace AN/APQ-153 radar (X kg) or AN/APG-69 radar (80 kg) with PIRATE IRST (48 kg). Weight loss: 32 kg

      So you now have an F-5E weighting 4.275 kg empty, 7.083 kg loaded, 6.045 kg combat weight. At combat weight, wing loading would be 350 kg/m2 and TWR 0,75. Further weight reduction could be possible if airframe is to be made out of composites and not aluminum.

      M39 has a muzzle velocity of 1.030 m/s, rate of fire of 1.500 rpm and projectile weight of 101 g (so 12 rounds weighting 1,21 kg in first 0,5 s). GIAT 30 has a muzzle velocity of 1.025 m/s, rate of fire of 2.500 rpm and a projectile weight of 275 g (so 20 rounds weighting 5,5 kg in first 0,5 s). In other words, one GIAT 30 would equal 5 M39s in firepower.

      Like

      • Yes, a very interesting suggestion. Thank you.

        Here, an interesting note from Pierre Sprey’s analysis: (Comparing the Effectiveness of Air-to-Air Figthers F-86 to F-18)

        (…)”The F-5`s weaknesses are somewhat deficient acceleration, marginal rearward visibility and marginal combat persistence.
        The F-5E, with 15% less weight, would have corrected these deficiencies. As a result, its dominance is air-to-air over its contemporaries would have been considerably harder to ignore. Had the F-5E been developed as simply the J-85-21 up-engining of the 12,500 pound F-5A, then it could indeed have come in at about 13,00 pounds which would have resulted in a major performance improvement. Instead, design discipline was lost: each functional engineering group was left free to strengthen, expand or “upgrade” its subsystems and the F-5E grew 3,000 pounds to 15,500 pounds, thus cancelling out most of the benefit of the 25% in thrust and maximum lift coefficient.”

        Like

  7. Xplane said

    Sorry, I am in late.
    Going back to the engines comparition, it seems that they all share the same technology but different choices have been made to fullfit different needs.

    For instance, EJ-200 and M-88 are pretty close to each over in term of conception and basic performance but one is devoted to high and fast domaine while the over is able of agility in low speed and can be repared quickly without final testing phase for Navy’s needs on the CDG carrier.

    Like

  8. Chris said

    I wonder, F119 vs M88 vs EJ230.

    – Maintenance would favor the M88, so it’d likely enjoy the sortie rate advantage; perhaps amplified by cost; plus it would be able to handle rough fields the most well among the 3
    – EJ230 would be somewhat in between
    – F119 type FLX (let’s say a hypothetical FLX around the F119 with no thrust vectoring) would enjoy a very large performance advantage and be much less vulnerable to being “bounced” while being able to bounce aggressively, but would be outnumbered both in sortie rate and number of aircraft per x amount of money

    The really interesting question then becomes would the F119’s superior performance be able to compensate, assuming comparably skilled pilots and comparable transient performance, wing loading, and other factors, for the losses in numbers and sortie rate?

    I haven’t taken the time to research this matter, but would it be possible to push up the F119’s performance even more – why does the F135 on the F35 give that much more thrust?

    “That is unavoidable, though, as it results in better efficiency (assuming all other factors are equal).”

    Yep. The really interesting question though will be, how far can materials sciences push the temperature?

    1700C is doable
    http://www.mhi-global.com/company/technology/review/pdf/e503/e503001.pdf

    They are using ceramics I would guess for such temperatures.

    Like

    • picard578 said

      As far as FLX goes, F119 has lower thrust-to-drag and thrust-to-weight ratios than the EJ230. Overall fighter’s TWR *might* go up, but that is not certain since larger engine would mean larger aircraft, plus the F119s higher SFC would mean that higher fuel fraction would be required. You could easily end up with a Rafale-sized aircraft – in fact, F119 is about the size of the F-16s F110, and F-16 is 15,06 m long, just shy of Rafale’s 15,3 m.

      So the F119 FLX would be 15,1 m long, with 9,8 m wingspan. Empty weight would be 7.199 kg, with 5.518 kg internal fuel. Armed empty weight would be 8.333 kg. Combat weight with 10 missiles and 120 gun rounds would be 11.092 kg. With wing area of 43 m2 and 16.783 kg of thrust, wing loading would be 258 kg/m2 and TWR would be 1,51. However, 20 minute supersonic cruise would use up 60% of internal fuel compared to 44% now, though cruise speed could be as high as Mach 1,8. Thus it could cruise for 15 minutes at Mach 1,8; this would cover 491 km compared to 20 minutes at Mach 1,55 which would cover 546 km.

      Unit flyaway cost would be 51 million USD.

      In other words, an improved Gripen NG.

      Like

      • Chris said

        Ah I see.

        I suppose then FLX is the best compromise overall. Smaller and you’d end up with a point defense type interceptor with limited range. Larger and you end up with … what you described above.

        Like

        • picard578 said

          Precisely. F119 may be the best engine overall, but fighter aircraft is a system composed of parts. It is useless to have parts in a system that are individually best performing if the system as a whole doesn’t perform well because interaction between parts is not optimal.

          Which is another thing that US military doesn’t get.

          Like

  9. Chris said

    You can see that sort of a mentality elsewhere in tactics as well.

    This report here found that for every intended target killed by drones, the strikes have killed 28 “unidentified” (most likely innocent) people:
    http://www.reprieve.org/uploads/2/6/3/3/26338131/2014_11_24_pub_you_never_die_twice_-_multiple_kills_in_the_us_drone_program.pdf

    Focusing too much on the targets and too little on the external effects.

    What I’m interested in is maximizing thrust to weight as high as possible. In general, the lower the bypass ratio, the higher the thrust to weight, until of course a turbojet is reached, which (barring a ramjet) has the highest thrust to weight.

    The GE J85, an engine that went into service in 1960 had variants that could achieve a TW of almost 8:1 in the 1960s. The civil aviation variant too the CJ610 was very powerful too. Later variants had lower TW because of course in civil aviation, reducing fuel consumption became the priority. Witness the development of the CF700, where fuel consumption was reduced but TW went down. You can see this development today with really high bypass turbofans in civil aviation.

    That makes me wonder if a modern turbojet could do even better today – or at least lower the fuel consumption (higher inlet temperatures).

    There are other trade-offs. Pressure ratio for example. Higher means more efficient, but a heavier engine (more materials needed). I suppose you’d have to consider the increase in engine mass vs the increase in fuel consumption.

    Like

    • picard578 said

      This mentality of target servicing / target processing lost US the Vietnam war.

      “What I’m interested in is maximizing thrust to weight as high as possible. In general, the lower the bypass ratio, the higher the thrust to weight, until of course a turbojet is reached, which (barring a ramjet) has the highest thrust to weight.”

      True. Which is why a turbojet might be the best option: if you compare turbofans to turbojets, latter tend to have some 25-30% greater thrust-to-weight ratio. Turbojet EJ200 could have a TWR as high as 12:1, plus it would be lot lighter and smaller in diameter than the current EJ200. That would allow smaller, skinnier airframe to be wrapped around it, reducing weight and improving supersonic performance (talking about the FLX here).

      Like

      • Chris said

        I’m thinking with a turbojet, other options are possible. Deleting the afterburner could bring even more dry thrust savings and/or higher fuel fraction. The real question becomes, is having an afterburner a huge advantage? You’re only ever going to use it infrequently and it does come at the expense of dry thrust performance.

        Another consideration is that a turbojet might actually be better for an airplane like the FLX. It’s designed for mostly supersonic flight for much of its life. Most aircraft today only go into supersonic mode for short periods. Only a handful of aircraft were designed for mostly supersonic flight – the Concorde, perhaps the SR71, and I believe there were a couple of Soviet era designs.

        But the thing is, I think the US lost the Vietnam War when it started fighting it. To the Vietnamese, the US was no different from the French in being an Imperialistic power. Perhaps the same thing could be said about the 2003 invasion of Iraq.

        Like

        • picard578 said

          “Deleting the afterburner could bring even more dry thrust savings and/or higher fuel fraction. The real question becomes, is having an afterburner a huge advantage? You’re only ever going to use it infrequently and it does come at the expense of dry thrust performance.”

          Afterburner is an emergency option, you don’t need or use it often, but when you do need it, you’ll be glad it’s there. So unless you can achieve TWR of cca 1,2 at combat weight on dry thrust only, you’ll need the afterburner.

          “Another consideration is that a turbojet might actually be better for an airplane like the FLX.”

          Correct, but there isn’t a turbojet that fulfills my requirements. Most important advantages of turbojet are high thrust-to-drag and thrust-to-weight ratios at dry thrust. Only turbojet I can think of that could be used for the FLX is the GE J79, which has inlet diameter of 97,2312 cm, dry thrust of 52,9 kN, dry TWR of 3,1:1 and dry TDR of 7,12 N/cm2. EJ230 I used has inlet diameter of 70 cm, dry thrust of 60 kN, dry TWR of 5,7:1 and dry TDR of 15,59 N/cm2. So using an existing turbojet would bring no advantages, in fact larger size (4,16 vs 1,72 m3), weight (1.750 vs 989 kg) and SFC (0,85/1,97 vs 0,74/1,7 kg/kgf h) would lead to larger, heavier fighter that would still have less thrust than the FLX as designed, on top of the inferior performance of the engine itself (primarly lower thrust-to-drag ratio).

          Like

      • Andrei said

        “The real question becomes, is having an afterburner a huge advantage?”

        In my opinion the afterburner is a relic of earlier age of jet propulsion when the dry thrust to weight ratio of jet engines was much lower. Currently engines are powerful enough that one can achieve very high thrust to weight ratios without using afterburner. Deleting the afterburner would probably increase that thrust to weight ratio even more, because the afterburner ads about 200 kg in weight and about doubles the length of the engine.Without an non-after-burning engine one has a flat-out reduction of 200kg in weight but more importantly the aircraft can be shortened by about 2 meters by deleting the section of the fuselage that is meant to make the engine fit but has no other functionality (there are no fuel tanks there for example) which leads to a lower wingspan and, all in all a lot more, weight saving in the structure without loosing fuel tank space, as the shortened sections, the aft fuselage and the wing tips don’t carry fuel.
        Picard it might be an idea to design an FLX with a non-after-burning variant of the EJ-200. We know that such a variant can be made as Eurojet has offered an non-after-burning variant of the EJ-200 for the re-engining of the AMX aircraft in the late 90s. http://www.flightglobal.com/pdfarchive/view/1999/1999%20-%200943.html From this we deduce that the non-after-burning EJ-200 variant would be about 2 meters in length, as it would have to fit in the same volume of the Spey engine, about half the length of the standard variant which is 4 meters in length. Also taking into consideration that future variants of the EJ-200 like the 230 have the same dimensions like the original probably a non-after-burning variant of the later models of the EJ-200 would still have the same dimensions as the Spey but at considerably more power.

        Like

        • picard578 said

          “In my opinion the afterburner is a relic of earlier age of jet propulsion when the dry thrust to weight ratio of jet engines was much lower. Currently engines are powerful enough that one can achieve very high thrust to weight ratios without using afterburner.”

          Actually, no. Current engines achieve TWR at dry thrust which older engines needed afterburners to do, but as I said to Chris: until you can have a fighter that achieves thrust-to-weight ratio of 1,2 at combat weight with dry thrust alone, you’ll need the afterburner. It is a very good emergency option, after all.

          “but more importantly the aircraft can be shortened by about 2 meters by deleting the section of the fuselage that is meant to make the engine fit but has no other functionality”

          Not necessarily, no matter how short the engine is, aircraft has to obey the area ruling, which places some constraints on minimum length. In other words, engine diameter has impact on aircraft length as well. Gripen E will be longer than Gripen C in part because it has to preserve the area ruling and fineness ratio.

          “Picard it might be an idea to design an FLX with a non-after-burning variant of the EJ-200.”

          I don’t think so, it would have the exact same dimensions as the current FLX except the engine would be further back and slightly lighter. But without the afterburner, FLX would have a TWR of 0,9 at combat weight – or 0,97 if you use as-of-yet-nonexistent EJ270. And the FLX has two minutes of maximum afterburner in standard combat radius calculation, which can be extended by using lower afterburner settings.

          In fact, if you look at the current FLX design, it is entirely possible by reduce its length by maybe a meter – only the inner center portion of the fuselage would have to be redesigned. But I’m worried that the FLX is too “fat” as it is, though it resembles Rafale more than anything.

          Like

      • For instance:

        F404-GE-402 (with afterburner):
        weight: 1.035 kg
        length: 4 meters

        F404-GE-100D (non afterburner):
        weight: 825 kg
        length: 2,30 meters

        But I think you will need a jet pipe for non afterburner engines at least the same length of an afterburner equipament.

        Like

      • Andrei said

        “Yes, and as I said to Andrei, afterburner is a good emergency option.”

        It’s a emergency option but I don’t know how good it is 😀

        “Not necessarily, no matter how short the engine is, aircraft has to obey the area ruling, which places some constraints on minimum length. In other words, engine diameter has impact on aircraft length as well. Gripen E will be longer than Gripen C in part because it has to preserve the area ruling and fineness ratio.”

        Actually you have to shorten it. Area rulling can be fine tuned by adjusting various thickness adding/removing bumps etc. with the help of computers it has come a long way since the Coca-Cola bottle shape of the F-5. Gripen E’s increased length has more to do with the fact that they increased fuel fraction by adding more tanks around the center of weight that translated to an fattening of the body and resulted in an increase of length. Which wouldn’t be the case with what I suggested because by having a smaller weight you can also reduce the quantity of fuel. But one other variable you have to take into account especially for supersonic fighters is center of weight. By not shortening the aircraft and keeping the engine in the same position the center of weight of the engines moves about 2 meters forward which translate in a move forward of the whole center of weight of the aircraft which leads to increased stability especially in supersonic. So you have to shorten the aircraft.

        “I don’t think so, it would have the exact same dimensions as the current FLX except the engine would be further back and slightly lighter.”

        Could you please do me a favor and redesign the 10 m long version with an non-afterburning EJ 270 and see what comes out? Maybe it will not be an air-superiority fighter but it might be a dammed good point-defense fighter.

        Like

        • picard578 said

          “It’s a emergency option but I don’t know how good it is”

          50% more thrust for 25% more weight… granted, it does blow up fuel consumption.

          “Area rulling can be fine tuned by adjusting various thickness adding/removing bumps etc. with the help of computers it has come a long way since the Coca-Cola bottle shape of the F-5.”

          To an extent. But engine diameter and cockpit size drive the aircraft’s minimal crossection, which in turn drives its minimal length. I don’t see much gain in removing the afterburner in terms of aircraft length.

          “Which wouldn’t be the case with what I suggested because by having a smaller weight you can also reduce the quantity of fuel.”

          To an extent. But see what I wrote above, you wouldn’t gain much beyond reduction in the engine weight.

          “But one other variable you have to take into account especially for supersonic fighters is center of weight. By not shortening the aircraft and keeping the engine in the same position the center of weight of the engines moves about 2 meters forward which translate in a move forward of the whole center of weight of the aircraft which leads to increased stability especially in supersonic.”

          Actually, afterburner is just one big tube with few extras, most engine weight is in its frontal section, one responsible for dry thrust. And Cg is calculated for an aircraft as a whole, deleting 2 meter afterburning section of the engine would result in far less than 2 meters of Cg shift (no more than 45 cm for a 14 metre aircraft). Further, removing the afterburner would result in engine being moved backwards, you don’t want the engine plume burning off the airframe.

          “Could you please do me a favor and redesign the 10 m long version with an non-afterburning EJ 270 and see what comes out?”

          Not likely, considering that the 10 m version is completely unrealistic.

          Like

  10. Chris said

    I guess the way to put it would be, let’s say that you have 1100 non-afterburning FLX vs 1000 afterburning FLX (let’s say that it’s 10% all told cheaper to operate).

    Would the 1100 non-afterburning FLX be at a drawback? If not, then it’s probably would the non-afterburning type.

    Actually there might be other benefits. The non-afterburning type might get a few more flight hours being somewhat cheaper to operate as well.

    Like

    • picard578 said

      As I said, afterburner is a good emergency option. If your air base is suddenly under attack (enemy has managed to sneak up, or distance simply does not allow early warning – as is the case with Israel), then you want to be airborne and at altitude pronto. As range is not a concern, and in any case FLX has a lot of fuel for aircraft of its size, you will light up maximum afterburner and stay in it till you reach the desired altitude. In such situation, where you only basically need to take off and land, FLX has enough fuel avaliable for 8-9 minutes of maximum afterburner – and afterburner *will* be required, considering that post-takeoff FLX will be at near to maximum combat weight (W 10.375 kg, WL 320 kg/m2, TWR 1,01) while attacking aircraft will have expended some fuel getting there in the first place (Su-35 combat weight 23.383 kg, WL 377 kg/m2, TWR 1,24).

      And keep in mind, situation I have described is a very real possibility for quite a few NATO and EU members – Norway, Sweden, Finland, Croatia…

      Also, afterburner is quite simple compared to rest of the engine, so I don’t think in really adds that much in terms of maintenance or other expenses (except fuel consumption, but it is not a concern during normal peacetime ops). Further, having a long metal tube aft of the engine core helps to reduce the IR signature during normal operations.

      Like

  11. “Could you please do me a favor and redesign the 10 m long version with an non-afterburning EJ 270 and see what comes out?”

    An interesting idea.

    I think you can reduce lenght (FLX) modifying the nose cone, it seens too large since there are very few equipament. A better shape would improve aerodynamics, radar sig,weight, lenght,etc.

    See the nose cones:
    Mirage V (non radar)
    YF-16
    Draken 35XD Danish version (non radar)
    F-8 Crusader (Reco version non radar)

    But a non afterburner version, it would not reduce the length, since, as I said, the jet pipe would force a repositioning of the engine,in some cases a jet pipe is even longer than an afterburner.

    Like

  12. Andrei said

    “But I think you will need a jet pipe for non afterburner engines at least the same length of an afterburner equipment.”

    You need a jet pipe only if you are forced by center of weight issues to install the engine more forward. This was necessary with older aircraft because they were designed for stability and for that the center of weight had to be forward of the neutral point which is normally give or take at about 30% of the chord of the wing., which in a normal planform is placed quite towards the forward part of the aircraft. So seeing as the engine was one of the heaviest components they tended to try to put it in the center of mass. Nowadays with delta wing which pulls the neutral point aft at relaxed stability which allows you to have the center of weight aft of the neutral point one can put the engine at the extreme aft of the aircraft and thus you don’t need more jet pipe then the one the engine comes equipped and also the modern nozzle the aircraft comes equipped with prevents one from jury rigging one 😀 So if an engine is two meters long without after burner it will be just two meters long not two meters plus jet pipe.

    Like

    • I am thinking about only the engine problems.
      I think wihout a jet pipe, you will have serious problems with pressure and temperature exaust measures affecting engine’s performance.

      http://www.nasa-usa.de/centers/dryden/pdf/88068main_H-1375.pdf

      Like

    • Besides, having the last turbine stage just in the tail end is not a desirable feature for a fighter aircraft (IR sig).

      Like

    • Anyway,

      The SNECMA Atar 8K-50 has a very short jet pipe. Almost nothing, maybe less than one meter.

      Like

      • Andrei said

        So dose the Honeywell F124. Here is a cutaway of the Aermachi M 346 http://www.flightlinearts.com/Portals/0/images/Portfolio/AermacchiM346Cutaway.jpg .The representation of the engine seems to have the jet pipe installed (which is more of a nozzle then a pipe) and it seems do be about half the length of the engine, so that means about 85 cm.

        “True. Which is why a turbojet might be the best option: if you compare turbofans to turbojets, latter tend to have some 25-30% greater thrust-to-weight ratio. Turbojet EJ200 could have a TWR as high as 12:1, plus it would be lot lighter and smaller in diameter than the current EJ200. That would allow smaller, skinnier airframe to be wrapped around it, reducing weight and improving supersonic performance (talking about the FLX here).”

        Okay I’ll drop the question of of non-afterburing turbofan versus after-burning turbofan, you might be right that considering what’s on the market today afterburner is still a must. But taking into consideration your quote above a modern turbojet might not require afterburner to deliver 1,2 to 1 Thrust to Weight at combat weight. I mean a non-afterburing Turbojet EJ 200 could deliver 7200 to 7800 kN at maybe 600 kg and with weight savings associated with a skinnier and maybe shorter fuselage in adition to an engine weighing almost half, the empty weight of the FLX could be around 3.5 tons. So maybe the question should be why are people so fixated on turbofans which are better for subsonic flight and they try to squeeze supercuising performance out of them when the logical solution would be to design a turbojet with modern materials. Basically since the F 119 was designed for the F-22, a supercrusing air-superiority fighter, they should have requested a jet-engine not low bypass turbofan.
        I hope in the near future they have a realization, like the RAF did when they built the Mosquito in WWII, that just because a technology seemed to be out dated 10,20,30 years ago (wooden construction for the Mosquito, turbojets for modern fighters) it doesn’t still have do be the case if one uses newer techniques and materials. It upsets me a lot to see a lot of old ideas that were tried and did not deliver the desired performance and are never revisited again (the fan in wing VTOL I talked about earlier, turbojets etc.)

        Like

        • picard578 said

          “So maybe the question should be why are people so fixated on turbofans which are better for subsonic flight and they try to squeeze supercuising performance out of them when the logical solution would be to design a turbojet with modern materials.”

          Reason is simple – up until relatively recently, materials science was not advanced enough to permit sustained supersonic cruise, and even modern fighters don’t typically carry enough fuel to allow sustained supercruise. So supersonic performance was sacrificed for subsonic one – logical considering that such aircraft would only spend maybe 1% of the time at supersonic speeds.

          Like

      • Andrei said

        Yes. But now things have changed since supersonic cruise is feasible, an fighter might spend 90% of it,s time at above Mach .8 which is precisely the starting point were turbojets become better then turbofans. An basically that was the mission profile of the ATF requirements from which the F-22 evolved.

        Like

      • Mike said

        I haven’t done the maths but I suspect designing a cheap interceptor almost purely around high supercruise might allow it to overtake a strike package which is returning to base.

        Hence taking the F35 as a baseline it’s range characteristics were determined by the number of suitable airbases from which strikes against Iran, Iraq or North Korea could be launched without needing AAR. It hasn’t met this design characteristic but assuming 450nm as an average an interceptor which could crank out 1000 kts at cruise ( mach 1.8 at altitude) could probably overtake most parts of a package and have those huge jet pipes as glittering targets in it’s IRST as they return to their ( known) base.

        Even assuming a worst case, F35s only detected when bombs on target), I think it is feasible.

        Like

        • picard578 said

          “I haven’t done the maths but I suspect designing a cheap interceptor almost purely around high supercruise might allow it to overtake a strike package which is returning to base.”

          Or even before it gets anywhere. FLX with 3 external tanks and 6 AAMs can cruise for 50 minutes at Mach 1,25 and distance of 372 km from the base, or for 20 minutes at same distance and Mach 1,55 without external fuel tanks. Rafale can likely cruise at Mach 1,4 for 20 minutes at distance of cca 150-200 km from the base.

          “It hasn’t met this design characteristic but assuming 450nm as an average”

          Keep in mind that nearly all Western fighters – even stealth ones – are designed under assumption of using external fuel tanks for getting to the combat area.

          “Even assuming a worst case, F35s only detected when bombs on target), I think it is feasible.”

          Against a well-designed fighter aircraft, a strike mission in the F-35 is basically one-way suicide run. Quite likely unsuccessful one as well.

          Like

  13. Ruy said

    Segundo eu li aqui no forum um f404 pode perder 20% de peso retirando seu afterburner. Essa relação seria aproximadamente a mesma em um F414EDE ou EJ230/270?

    Like

    • picard578 said

      Sorry, I don’t understand Spanish and GT isn’t the best. IF I have understood correctly, then yes, you do loose cca 20% of weight by removing the afterburner section.

      Like

  14. […] capable of maintaining Mach 1,2 for 150 miles. F135 will, at maximum dry thrust and at test bench, produce 12.700 kgf of thrust while consuming 11.089 kg/h. 150 miles at 30.000 ft and Mach 1,2 would take […]

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  15. […] https://defenseissues.wordpress.com/2014/12/06/fighter-aircraft-engine-comparision/ […]

    Like

  16. […] Fighter aircraft engine comparison […]

    Like

  17. Heikki Kultala said

    I thought F-135 is mostly just an F-119 with bigger compressor and higher bypass ratio, with same chamber, to get more low-speed thrust with same power consumption. So how can it then consume more fuel than F-119 when running dry?

    Like

  18. Anonymous by request said

    Regarding the notes, as Low Bypass Turbofans get better at supercruise the lower their bypass is, I would guess that the J85/J97 would be even better yet, any explanation as to why they are not….???

    Like

    • picard578 said

      It has to do with thrust. What you noted about bypass is only true for engines of similar technological level, which is to say similar thrust-to-weight ratio, and similar size. Thrust-to-weight ratio obviously increases thrust-to-drag ratio, but due to the square/cube law, a larger engine will have higher thrust-to-drag ratio, all other things being equal. J85 has TWR of no more than 8,5, which is quite good, but not to the levels of newest turbofans.

      Like

  19. Cat said

    Regarding the notes, as Low Bypass Turbofans get better at supercruise the lower their bypass is, I would guess that the J85/J97 would be even better yet, any explanation as to why they are not….???

    Like

  20. Amphy said

    The Bypass Ratio for the F-119 is incorrect, it is .3:1.
    From Wikipedia: “Pratt & Whitney’s design changed to incorporate a 15% larger fan, increasing bypass ratio from 0.25 to 0.30.”

    Like

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