Defense Issues

Military and general security

Single vs twin engined fighters

Posted by picard578 on August 9, 2014

Single engined fighters have typically been favored due to their low procurement and operational costs, ease of maintenance and assumed better air-to-air performance. Yet there is also a belief that single-engined fighters are inherently less survivable and lower-performance than twin-engined fighters.

Fighter aircraft of World War I and II were invariably single-engined. Few twin-engined fighters – P-38 and Me-110 – had disastrous performance against single-engined fighters of the period (Me-109 and Spitfire, respectively), as they were too large, too heavy and too inferior in maximum g and roll performance; loosing one engine spelled doom for fighter as enemy fighters would down a straggler. In the end, P-38 had to withdrawn from Europe in fighter role (it did continue in photo reconnaissance role) due to heavy losses. For these reasons, twin-engined configuration was typically reserved for lumbering bombers, and night fighters whose only task at the time was bomber-hunting (Me-110 and Mosquito were notably successful in such role). Most successful Western fighters – F-86, Mirage, F-16 – have also been single-engined, and Soviet fighters designed after World War II (MiG-17, MiG-21) followed the suit. Only twin engined fighter of the era was English Electric Lightning, but it was not the most successful fighter despite being the first fighter aircraft to supercruise. Twin engined fighters only became popular when multirole requirements became standard, starting with F-4. But F-4 had disastrous performance in air combat considering its cost, and its ground attack performance was not stellar either.

Single engined fighters tend to be cheaper to buy and operate, easier to maintain and have lower basing requirements. Easier maintenance is primarly due to twice the number of engines means twice the work and twice the likelyhood of something going wrong. It also means that twice as many spare parts are needed, increasing aircraft’s logistical footprint. Even with a possible benefit of fewer peacetime losses (which, as shown later, is nowhere near certain), a fleet of single-engined fighters is still less expensive in both procurement and maintenance costs than a fleet of twin-engined fighters, and a force of single-engined fighters will almost always outperform a force of twin-engined fighters that costs same to operate and maintain.

This means that they provide advantage in two most important areas: 1) pilot training and 2) allowing larger number of combat sorties for the same cost. Further, small size tends to make them easier camouflaged on the ground. As a result, only twin-engined fighter ever to become the frontile fighter was the F-5, primarly due to its small size and weight.

Reasons why single engined fighters tend to have better combat effectiveness are several. Single engined fighters tend to be smaller, lighter, and better optimized aerodynamically, which automatically improves survivability in a dogfight. Having one engine means that mass is distributed closer to the centerline axis, which reduces roll inertia and improves roll onset rate. F-16 also has comparable roll rate to the F-22 despite latter’s thrust vectoring allowing it to use all control surfaces to roll. Wing loading is also typically lower for single-engined fighters. Comparing Western jet fighters up to 1980, only fighters with less than 500 ft area were single-engined ones (with sole exception of the F-5), and smallest modern Wester fighters are the F-16 and Gripen, both single-engined. Smaller size means that they have surprise advantage, as they are harder to acquire and track either visually or with optical (visual, IR) sensors; small size combined with better transient performance also means that they are more likely to slip out of sight after being acquired. Lower drag oftentimes (though not necessarily) means higher cruise speed despite often lower TWR – fastest cruising fighters of the 1950-1980 era were single-engined J-35, Mirage III and F-106. Mirage III was actually able to achieve Mach 1,3 without reheat, though its economic cruise speed was around Mach 0,92, as it was for J-35 and F-106. Gripen C similarly is capable of cruising at Mach 1,1 at dry thrust and with 6 missiles despite being underpowered, and its economical cruise speed is again Mach 0,92. F-16 can achieve Mach 1,1 at dry thrust and with two missiles, most likely due to added drag of horizontal tail, while the F-15 can achieve a cruise speed of only Mach 0,71 despite far higher thrust-to-weight ratio, primarly due to the high cruise drag. Single-engined F-104 could achieve cruise speed of Mach 1,1 and actually has better supersonic range than the F-22 (it could maintain Mach 2 for 15 minutes, whereas F-22 can maintain Mach 1,5 for about as long.*). An F-104A equipped with the -19 engine could maintain level flight at Mach 2 and 22.000 meters on a cold day.

Better thrust-to-drag ratio of single-engined fighters also allows better acceleration – oftentimes significantly so. F-16 has the best acceleration of all US teen fighters, and single-engined F-106 and J-35 have acceleration comparable to twin-engined F-4E, while similarly single-engined F-104A outperforms all three previous fighters by a significant margin. In fact, F-16Cs acceleration is better than that of the F-22A in transonic region (Mach 0,8-1,2 at 30k ft in 28 s vs 33 s for the F-22), though the F-22 has better supersonic acceleration. Both F-16 and the F-22 have significantly superior acceleration and endurance compared to the F-15 due to latter’s high tail-boat drag.

{Note: increased drag in twin-engined fighters is primarly a result of three factors. First is increased tail-boat drag due to shaping required to place two engines next to each other – there is an area between the engines which typically ends in a flat plate if engines are close together, and if not then additional fuselage required to separate engines still leads to higher drag. Second one is increased engine-face drag [F-16s F100-PW-229 has 129,7 kN of thrust and 88 cm inlet diameter (6.082 cm2 area), while F-18s F404-GE-402 has 78,7 kN of thrust and 79 cm inlet diameter (4.902 cm2 area). Thus, thrust-to-inlet area ratio would be 21,33 N/cm2 for the F-16 and 16,05 N/cm2 for the F-18. Both engines have same thrust-to-weight ratio and use similar technologies. For Gripen’s RM12, ratio is 20,4 N/cm2 (80,5 kN, 3.944 cm2)]. This is a problem since engine drag accounts for a significant proportion of total fighter cruise drag. Third one is typically wider body leading to higher form and profile drag and inferior area ruling, which itself leads to higher wave drag.}

Single engined fighters also tend to have higher fuel fraction, and thus combat persistence, than twin-engined ones – only fighters USAF produced from 1950 to today with fuel fraction of 0,3 or above are single-engined F-101, F-8, F-16 and F-35. Combined with lower drag of single-engined fighters (greater range at same fuel fraction), this resulted in the F-8 and the F-16 having significantly greater persistence and range than their twin-engined counterparts (F-15 and F-18 for the latter; speaking of USAFs competence, USAF did not want a single-engine fighter to have a greater range than the F-15, but focused on total fuel capacity as opposed to the fuel fraction and thrust-to-drag). With modern European fighters situation is opposite, mostly due to differing requirements France, Sweden and Eurofighter consortium had for their fighters. That being said, Gripen E is expected to have almost as high fuel fraction as, and better endurance/range than, twin-engined Rafale.

And as counter-intuitive as it may sound, single-engined fighters have better combat survivability as well. Most modern Western fighters have engines so close together that any amount of damage taking out one engine is almost certain to take out another as well. Even if a twin-engined aircraft loses a single engine without another one getting taken out, it immediately looses 50% of the thrust and 81% of the performance, making it a sitting duck and easily killed by the opponent. One of reasons for that is large amount of assymetric thrust generated by only one working engine, and designs most likely to suffer loss of only one engine in combat are also ones that have widest engine spacing and thus greatest amount of assymetric thrust and roll inertia. Due to all above factors, twin-engined fighters are more likely to get hit in combat while not being any more likely to survive getting hit.

Twin engined designs do not necessarily have better peacetime survivability either. F-106, despite being single-engined, had 15 losses in first 90.000 hours, compared to 17 for the F-4. In the first 213.000 hours, it had 26 losses, compared to 44 for the F-4. It can be seen that the more complex F-4 had worse loss rate than the F-106 despite having two engines, and while F-106s loss rate improved, F-4s grew worse. Single-engined F-105 also had low peacetime loss rate.

Loss rate of the F-104 was 26,7 losses per 100.000 hours, compared to 12,2 for F-106 and 20,7 for the F-4. Main reason of losses was not the single engine, but rather USAFs bureocratic stupidity. Namely, once Lockheed gave USAF F-104 (a point defense interceptor), USAF ordered Lockheed to modify F-104 into a nuclear-capable bomber. Main cause of F-104 losses in German service was improper pilot training – in the same period Spain had no F-104 losses despite flying them in similar conditions. Specifically, German pilots received conversion training on Starfighters in United States – in desert, with clear skies and lot of room. Once instruction regiment was changed to something appropriate to Central European conditions, loss rate improved drastically, to the point that it was comparable to twin-engined fighters of the day. Pilots also often overrode aircraft’s AoA limiter despite F-104s propensity to pitch up and enter spin at high angles of attack. Further, Luftwaffe used F-104s in inappropriate fighter-bomber role, which led to major use at low altitudes as well as to installation of heavy ground-attack electronics and INS, to the point that it was considered “overburdened” with technology. In Canada, single-engined Tutor, T-33 and CF-104 were more reliable than twin-engined T-37, T-38 and CF-5. While CF-104s were dubbed “Widow Makers”, that did not have anything to do with number of engines but rather with the fact that CF-104s were pressed into a low-level bombing role despite being designed as high-altitude Mach 1,4 bomber interceptors. They had very small, razor-sharp wings that were suitable for high-speed supersonic flight; however, at low speeds high wing loading and bad separation characteristics (due to sharp edge) meant that they were prone to stall as soon as the fighter maneuvered, and low altitude did not leave any room for recovery.

Swedish JAS-39 has a better safety record than the F-18 despite having one engine less – 13% of Canada’s CF-18s have been lost in crashes compared to 2% of Gripens; a loss rate of 0,36% per year versus 0,08% per year for Gripens. Rafale suffered 4 crashes in 64.000 hours, 3 were due to the pilot error. F-16 fleet logged 11 million flight hours by 2004, with 493 losses. Comparing Gripen with Eurofighter Typhoon, Gripen suffered 5 crashes total in 203.000 flight hours. None were related to either engine or aerodynamic configuration of the aircraft: 2 were due to underdeveloped FCS, 2 were due to the pilot error and 1 was due to ejection seat issue. Typhoon suffered 3 crashes total in 240.000 flight hours. One was due to double engine flameout and two due to unexplained reasons. F-22 reached 100.000 flight hours on 11.9.2011., and by that time had 4 losses.

Overall, F-15 had a crash rate of 2,36 per 100.000 hours and F-16 of 4,48 per 100.000 hours. Less than quarter of the F-16 losses were due to the engine failure, with leading cause of losses being FCS issues and human mistake. On the other hand, most F-15s lost have experienced engine fires, meaning that engine-related loss rate is actually higher for the F-15 than for the F-16. F-18 crash rate is 3,6 per 100.000 hours, and Gripen’s is 2,46 per 100.000 hours, compared to 1,25 for Typhoon and 6,25 for Rafale. F-16s safety has improved over time, with cumulative loss rate with 11.000.000 hours being 4,48 losses per 100.000 hours, cumulative loss rate at 12.000.000 hours being 3,55 per 100.000 hours and non-cumulative loss rate at 12.000.000 hours being 1,59 per 100.000 hours. F-22s loss rate is 4 in first 100.000 hours. As already mentioned, however, most losses were not engine-related: engine-related loss rate is 0,00 per 100.000 hours for Gripen and 0,42 per 100.000 hours for Typhoon.

MiG-21 is much maligned in India due to its high crash rate. However, many crashes are not a result of the single-engined design but rather of bad cockpit visibility and high landing speed. 40% of crashes are in fact result of the human error. Further, MiG-21s have high total crash numbers because they constitute 75% of the IAF fighter fleet. Other problems include lack of simulators and inadequate maintenance. Many MiG-21s, and majority of spare parts, were produced locally in India and were not up to Russian (let alone Western) standards. Croatian MiGs are nearing end of their service life, and many of them had to have their service life extended beyond production limits and have insufficient maintenance. Crashes were in 2010 (cabin fell out, hit second MiG and both crashed) and 2014 (pilot bailed out due to the MiG catching fire in middle of flight due to the landing gear problem), but not a single CroAF MiG-21 was lost due to the engine problem.

Overall, statistics show that single-role air superiority fighters tend to be safer than contemporary multirole fighters regardless of number of engines (ref. F-106 vs F-4, F-15 vs F-16, Typhoon vs Rafale vs Gripen). And while loss of engine in a single-engined fighter invariably means that the aircraft is lost, engine is not the leading cause of loss (especially today), and lesser reliability of some other systems can make survivability benefits of having a second engine irrelevant.

And while very rare, it is also very possible to land a single-engine fighter with engine out. More common are crashes of twin-engine aircraft due to a single-engine flameout.

In the end, theoretical superior peacetime survivability of a twin-engined aircraft is neither large or certain enough to offset lower combat survivability and performance, typically smaller fleet size, higher maintenance downtime and higher operating cost. That being said, aircraft has to be well designed aerodynamically in order to take advantage of a single-engined configuration (ref. Gripen); single engined F-35 is the worst-performing Western fighter, and one of most expensive ones, due to two factors: bad aerodynamic design and weight more typical of twin-engined fighters. It is also likely to have high crash rate – not due to its single-engine configuration, but due to its extremely complex hardware (overly complex engine and avionics) and software (24 million lines of code) design.

While ground attack aircraft do benefit from having a second engine, their mission is fundamentally different in its nature and cannot be used to draw conclusions about survivability of air superiority aircraft. Even there, however, a second engine may not benefit (or may even harm) survivability if it makes aircraft comparably large.

EDIT 28.5.2015.:

During Gulf War I, A-10 suffered 5 losses in 8.084 sorties, a loss rate of 0,62 per 1.000 sorties. For comparison, 5 Harriers were lost in combat out of 3.342 sorties, a loss rate of 1,50 per 1.000 sorties, more than twice the A-10s loss rate. F-16s suffered 3 losses in 13.340 sorties, a loss rate of 0,22 per 1.000 sorties. However, F-16s typically operated at higher altitudes than the A-10s did. F-15E suffered 2 losses in 2.200 sorties, a loss rate of 0,91 per 1.000 sorties. F-18 suffered 3 losses in 4.551 sorties, a loss rate of 0,66 per 1.000 sorties. As it can be seen when comparing F-16 with F-15E and F-18, having a second engine was not a survivability advantage. Harrier’s low survivability was not due to a single engined configuration, but due to being employed at low altitude despite having no armor and having engine / nozzle configuration which made it extremely vulnerable.

EDIT 13.8.2016.:

Analysis of air operations in Vietnam and Arab-Israeli wars has revealed that 62% of losses of single-engined aircraft was caused by fuel fire, 18% was caused by the pilot being disabled, 10% by damage to control surafces, 7% by engine loss and 3% by structural damage.

Notes

*Additionally, my own FLX design can cruise for 20 minutes at Mach 1,5 at distance of 372 km from base, on internal fuel only. Pierre Sprey proposed a design in 1980 which could cruise for 20-30 minutes at Mach 1,2-1,6 at distance of 322-483 km from base, again on internal fuel only. As it can be seen, both are single-engined yet both achieve better supersonic range and/or persistance than the F-22.

Further reading

Single Engine – Cost Benefits, Reliability, Thrust by Air Marshal V.K. Bhatia
Today’s letters: Today’s single-engine jets are not ‘widow makers’ by Paul Russel
Mythbuster: Single engine safety

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45 Responses to “Single vs twin engined fighters”

  1. incar956 said

    Love your work Picard578 as always 🙂

    p.s

    Please tell me you’ve read “Boyd – the fighter pilot who changed the art of war”.
    Best book ever!

    Kind regards

  2. incar956 said

    That’s a pity. You would really enjoy it. I hope you get your hands on a copy one day.
    Bye for now – keep up the great work!

  3. Chris said

    The issue is that the MICC does not care about making good fighters, only making money. I doubt it knows what makes a good fighter even.

  4. Chris said

    There seems to be another fundamental problem with all of this: the command structure that let it happen.

    In most armies today, there are simply too many officers. The Germans in WWII when they ran their Panzer divisions had perhaps a staff of perhaps 10-20 men, and at times, even less than that. Today there seems to be a small city running the command of your typical division.

    1. Well, first it causes an internal race where officers are trying to “look good” to advance. It’s less about getting things done.
    2. Less firepower for any given army size. Could also lead to massive support structure.
    3. Combat performance becomes de-emphasized in promotion. Less initiative from officers and more politics.
    4. It would seem the higher ups are there because of their politics not ability.
    5. Endless, pointless briefings that are overly large. Slows down the tempo of the army.
    6. Then I guess the ones on top build up really cozy ties with their defense industries, get good jobs when they retire, etc.
    7. Leaves a peacetime culture. Not really suitable for war fighting.
    8. Very vulnerable to surprise attacks. If things don’t go according to plan, it all falls apart.
    9. Leads to micromanagement of troops on the front, which is counterproductive.
    10 Perhaps worse of all: silences the unconventional thinkers and the ones willing to take initiative.

    Compounding all of this, I imagine that this “small city” is probably not very mobile and against a good opponent, they’d probably make it a priority to take it out. An airstrike with a squad of maybe 4-5 CAS aircraft, a few kms behind enemy lines would devastate this “small city” of officers for each division.

    So you get these officers that build ties with the defense industry in an attempt to advance their careers and mess up everything.

    • picard578 said

      “Well, first it causes an internal race where officers are trying to “look good” to advance. It’s less about getting things done.”

      Combine that with US’s supremely moronic “up or out” policy…

      “Combat performance becomes de-emphasized in promotion. Less initiative from officers and more politics.”

      From what I’ve read, US submarine captains get releived whenever their sub runs aground, or even touches the seafloor. What you get from that is a bunch of scared, conservative incompetents.

      “It would seem the higher ups are there because of their politics not ability.”

      True. Similar to the WWII Wehrmacht, actually, but Wehrmacht had a culture where officer in the field was entirely allowed to outright ignore bureocrats in the OKW. Guderian and Rommel often had to go through Hitler to get anything done… good thing for them that Hitler trusted them enough for it to work, at least until 1942. You know that OKW was against tanks, assumed that cavalry is actually more important than tanks, and that a new war will be a rehearsal of World War I? (Similar to how USAF is against IRST in favor of radar, though unlike cavalry radar has never proven itself in combat against the competent enemy – very much the opposite).

      “Leaves a peacetime culture. Not really suitable for war fighting.”

      In any given war, US were relatively quick to learn new lessons, but even quicker to forget them afterwards.

      “Very vulnerable to surprise attacks. If things don’t go according to plan, it all falls apart.”
      “Leads to micromanagement of troops on the front, which is counterproductive.”

      Indeed. Which is exactly what happened to the overly-centralized French forces during the Battle of France in 1940. Leaves you thinking about centralization tendencies in Western militaries.

      “Perhaps worse of all: silences the unconventional thinkers and the ones willing to take initiative. ”

      Yes, I often had an impression that IQ of any given member of any given group is inversely proportional to size of that group.

      “An airstrike with a squad of maybe 4-5 CAS aircraft, a few kms behind enemy lines would devastate this “small city” of officers for each division. ”

      Which, ironically enough, could make the division *more* effective, assuming that officers in the field are trained and ready to pick up the slack (which, in Western militaries, they typically are. Arab militaries are another story – one of reasons why Iraqi military performed so badly was that all orders had to be confirmed by the main HQ, while officers in the field were too scared to take the initiative).

  5. Chris said

    Which, ironically enough, could make the division *more* effective, assuming that officers in the field are trained and ready to pick up the slack (which, in Western militaries, they typically are.

    I’m not so confident about that anymore. Western armies have been cutting training. Note that fighter pilots get 10 hours today and maybe 40-50 in the simulators. Ground forces have seen similar cutbacks.

    I have talked to tank operators before (both American and Canadian), one needs about ~1000km of tank training per year maneuvering and a couple of hundred shots firing the gun. The best the US ever did was 750-800 km. Today, it’s rarely above 600km and alarmingly, under 400km. According to the tankers I spoke with, being “good” with tanks can be a rather perishable skill. The other problem is the nature of the training. Often there isn’t an effort to make the training seem “random” that is, things do not always go according to plan and force the officers to improvise on the spot. There also has to be an effort to maneuver. American training I find tends to put a very strong emphasis on frontal assaults and straight lines. Man for man, the US probably has a very good force for frontal assaults, probably the best in the world. When it comes to maneuvering though, I’d be less confident. Although the invasion part of the 2003 Iraq War was relatively well executed, I suspect against a competent enemy, there would be a nasty surprise.

    Then there’s stuff like this:
    http://www.cbsnews.com/news/military-lowers-standards-to-fill-ranks/

    And this for officers:
    http://pogoblog.typepad.com/pogo/2011/11/todays-military-the-most-top-heavy-force-in-us-history.html
    http://pogoblog.typepad.com/pogo/2011/04/brass-creep-and-the-pentagon-air-force-leads-the-way-as-top-offender.html

    The bad economy may have helped the army somewhat, but it’s still not good.

    On the reverse side though, there are a lot of veterans from the Iraqi and Afghan wars who are probably tougher and better soldiers now that they’ve been through that. Naturally, combat experience has a way of doing this.

    I’m not sure what the net effect is though. Equipment training though has definitely fallen. There’s also a lot of equipment that should have been replaced from the Iraqi wars that never was.

    • Chris said

      Oh and then there’s stuff like this going on:
      http://www.komonews.com/news/local/95168184.html

      On that note, the stuff I said about the tank maneuvers, it is strictly anecdotal evidence, but it is definitely not looking good. I would like to see large scale figures for the armor and equipment training though – I suspect it will not be good.

    • picard578 said

      Yeah, I see what you mean.

      • Chris said

        Correction to earlier post: It should be miles (about 1 mile = 1.609 km). The Americans still do not use metric.

        Anyways, the point is, it’s unlikely that junior officers would think for themselves. They are probably more concerned with how to get the promotions so that they end up in those mini-city command posts and ultimately, work their way up to general.

  6. Chris said

    MiG-21 is much maligned in India due to its high crash rate. However, many crashes are not a result of the single-engined design but rather of bad cockpit visibility and high landing speed.

    I’ve been wondering about this one.

    Hmm … what is the right sized wing? Larger wing = lower wing loading, perhaps more room for fuel in wing, more lift from wing, perhaps better lift to drag ratio, but at the same time adds drag and decreases maximum speed.

  7. Chris said

    Size of the wing itself is a problem due to cruise drag and roll inertia (larger wingspan = greater roll inertia), it may also limit the maximum speed at lower altitudes.

    Hmm … that would probably lead to lower transient performance. The only other way would be to extend the wing closer to the nose. Then the canard would need to be modified. That would introduce it’s own set of issues though. Plane design is full of compromises, like all engineering.

    single engined F-35 is the worst-performing Western fighter, and one of most expensive ones, due to two factors: bad aerodynamic design and weight more typical of twin-engined fighters. It is also likely to have high crash rate – not due to its single-engine configuration, but due to its extremely complex hardware (overly complex engine and avionics) and software (24 million lines of code) design.

    There is actually one other reason why the F-35 would perform worst of them all, at least for the B variant. The Harrier became known as the “widow-maker”, having one of the highest if not the highest flight time:accident rates. A very high percentage of the accidents are during the vertical takeoffs and landings. Often these involve flame-outs or the engines ingesting something. It will never have the “rough field” sort of abilities that were advertised for sure. There have been accidents before where heavy crosswinds have caused the plane to have problems in the takeoff. The aircraft seems to be very vulnerable too to bird strikes and lightning. It is looking like the F-35B will share these problems.

    The other weakness is that the the nozzles in the Harrier, the lift fans, are in the mid-section of the aircraft. Whereas on a conventional aircraft, an IR missile is likely to seek the hottest point of the aircraft, the exhaust plume, and hit directly behind the aircraft, on the Harrier, the nozzles remain in operation in flight, so the missiles seek them and when they hit, they are much more likely to hit the actual plane. Typically missiles would hit right where the tail was because that was the hottest part. The end result is that the Harrier has a very large IR signature, for an aircraft of its size. Also, because the nozzles are facing the ground, this makes the aircraft much more vulnerable to shoulder launched IR missiles too (and probably IR missiles from SAMs). Compounding the problem, the way the aircraft was designed, there are a lot of hydraulic lines on the fuselage, so any missile that hit would be that much more likely to result in a kill.

    The F-35B lift fan doesn’t share this weakness, but it introduces it’s own set of unique weaknesses. Many of them appear to be similar to the Soviet-era Yak 141. During the early 1990s, there was a collaboration program between Yakolev and Lockheed Martin, where there were a few technological transfers. There have been claims that Lockheed more or less copied the Yakolev design, including the engine rotating mechanism. They share similar problems, as I hinted. The tail for example can be burned by the engine of both aircraft. But judging by the F-35’s progress, the problems are more severe than on the Yak. That’s probably because the F-35 is much heavier. There’s probably much less margin for error. The other big weakness is that the fuel surrounds the engine. From what I understand, the problems on the F-35B are much more severe than the F-35A. The Pk of a missile would probably be much higher than other aircraft. The end result is an airplane that has even lower payload, range, and maneuverability than the F-35A.

    Oh and, this being the MICC, they naturally did not add a gun. Only the F-35A has a gun. They had to design a “stealth gun pod” for the F-35B. The F-35C doesn’t have a gun either.

    • picard578 said

      Yeah. Plus they removed fire protection measures to save weight, and I believe they even made the skin thinner (so engine’s IR signature is even easier to detect).

      • Chris said

        End result is going to be a plane even worse than the F-35A in performance and reliability, while costing more for a capability that is not really useful.

  8. Chris said

    Also, adding to the statement on rough field capability, the Harrier has a myriad of inspections that have to be done before take-off because it is very vulnerable to sucking foreign objects into the intakes. For the F-35, because special heat absorbent material has to be used, there’s no way rough field capability would ever be possible. Certainly not dirt strips.

    In a real war, if the enemy were to attack these special airfields with these heat resistant tiles, then debris would be all over the ground, which would create a huge foreign object problem. FOB sweeps have to be done regularly in peacetime to operate VTOL. I’m not sure what the designers of any VTOL aircraft were thinking, particularly the British in the 1960s who did not have such a lavish budget.

    • picard578 said

      To quote: it seemed a good idea at the time. VTOL aircraft were intended to operate without air strips as same were certain to be taken out in the nuclear war. Now, after actually producing VTOL designs, it became obvious that they are too complex to actually operate in austere conditions, and require those same easily taken out air strips. But by then, US Marines have acquired a fetish for VTOL aircraft, and Royal Navy seems to have it too (though it might have been an idiotic budgetary choice too, seeing how STOVL carriers tend to be cheaper than CATOBAR ones).

      • Chris said

        This is likely to prove to be a very costly mistake, this fetish on VTOL. The V-22 is another example.

        At sea, short take off is still much cheaper than VTOL all things considered. Why you would need VTOL at sea though, when catapults and arresting gear are present is another matter. There’s a huge tradeoff in performance and reliability. Anyways, there seems to be a move towards electromagnetic catapults. It takes a lot of electricity, but the upside is you don’t have to spend energy desalinating the water.

        – I still think that an FLX-like aircraft combined with a sea version of the ALX would be the best combo, and could be built on an aircraft carrier perhaps of 30,000 tons or less.

        – On the small end, the lightest jeep carriers in WWII could be under 10,000 tons, but that was with piston engine aircraft.Casablanca Class for example was 156m long, was about 7,900 tons empty and perhaps 11,000 tons loaded. I suppose such an aircraft carrier might prove quite good though for an all-ALX carrier.

        – Between those two, I think that a 20,000-25,000 ton carrier might be possible though with FLX aircraft.

        Carriers IIRC tended to suffer higher crash rates. I suppose there’s more to go wrong. The landing in particular is a dangerous part of being on a carrier. I’m not sure what VTOL has to offer though here – probably not much either.

        On land … hmm. You’re still better off with a conventional FLX-like aircraft with some rough field capability.

        • picard578 said

          “– I still think that an FLX-like aircraft combined with a sea version of the ALX would be the best combo, and could be built on an aircraft carrier perhaps of 30,000 tons or less.”

          I have designed such carrier, but it won’t be posted yet.

          “I’m not sure what VTOL has to offer though here – probably not much either. ”

          More accidents, maybe.

          “On land … hmm. You’re still better off with a conventional FLX-like aircraft with some rough field capability.”

          Yeah.

      • Mike said

        It isn’t entirely a fetish. Vertical landing is hugely beneficial on a carrier in many ways. Indeed the biggest mistake made on the F35 was producing three variants rather than the two which studies suggested would be ideal.

        Put simply you can bring the planes on board quicker and safer with vertical landing. Using traps results in bolters and high approach speeds, not to mention stress on the aircraft.

        The most workable solution for the F35 was an air force A model and the marines and Navy sharing a B model. This was to use catapult assisted takeoff and land vertically. I have the RAND study around here somewhere.

        • picard578 said

          “It isn’t entirely a fetish. Vertical landing is hugely beneficial on a carrier in many ways.”

          Fighters can’t take off vertically with useful payload, so you still need an air strip. And even though carrier construction is simpler for STOVL fighters, payload is limited, and fighters themselves tend to be slow and unmaneuverable (only thing Harriers ever did was shoot down bombers, they never got used in an actual dogfight).

          “Put simply you can bring the planes on board quicker and safer with vertical landing. Using traps results in bolters and high approach speeds, not to mention stress on the aircraft.”

          That is true… but see the previous.

          “The most workable solution for the F35 was an air force A model and the marines and Navy sharing a B model. This was to use catapult assisted takeoff and land vertically. I have the RAND study around here somewhere.”

          I don’t think it was possible. F-35B lands vertically so it is not an issue for it, but for CATOBAR aircraft landing on a carrier there is a major issue of an approach speed. F-35A and B variants simply have too high wing loading to be used on USN carriers.

        • picard578 said

          Verical landing however turns aircraft into dogs when it comes to fighting, which is a problem since aircraft that land vertically typically fly from either smaller ships or jump-ramp carriers, which means that they can’t carry large payload either. So nearly useless for air superiority and of very limited usefulness in strike role… what is left?

  9. Canada shoulda opted for the F-16 Falcon… It would have been much better than the CF-18

  10. Andrei said

    The best option for VTOL in my opinion is to build hybrid air-ship carriers that take-off vertically carrying a squadron of conventional fighters and launch and recover them at 10000 meters. They could stay airborne for weeks and could probably revolutionize tactics as fighters could be airborne 24/7 and would have short response times.

  11. Silavite said

    I agree that the P-38 was a worse fighter than contemporary single engine designs, but because of cost and not performance.
    The P-38 had inferior transient performance for its first few models, but it became superior after the introduction of boosted ailerons.
    The P-38 also had a good turning circle, despite its girth, and its rate of climb was on par with the P-51.
    Source: http://www.wwiiaircraftperformance.org/mustang/Performance_Data_on_Fighter_Aircraft.pdf

    The reasons P-38s were relieved from duty in Europe were twofold. Firstly, there was the fact that they cost more than single engine fighters. Secondly, the P-38’s turbochargers had problems with icing in the early parts of their fighting over Europe.
    The P-51 also had some other advantages, like sharing the Spitfire’s engine, and good visibility.

    • picard578 said

      “The P-38 had inferior transient performance for its first few models, but it became superior after the introduction of boosted ailerons.”

      I very much doubt it. All other things being equal, P-38 would always have inferior transient performance compared to single-engined counterparts due to greater wingspan and different mass distribition (more mass away from the cg).

      “Firstly, there was the fact that they cost more than single engine fighters. Secondly, the P-38’s turbochargers had problems with icing in the early parts of their fighting over Europe.”

      Actually, P-38 was kept in photo reconnaissance roles, but it proved unable to effectively counter single-engined fighters.

      “The P-51 also had some other advantages, like sharing the Spitfire’s engine, and good visibility.”

      Agreed.

    • picard578 said

      Diving speed is also a critical shortcomings as it limits the ability to escape enemy attack.

    • Silavite said

      A more detailed analysis reveals that the P-51H (compared to the P-38L) has;

      ADVANTAGE
      Greatly superior maximum speed (mach .68 vs mach .80)
      Superior level flight speed (at all altitudes that I am aware of)
      Superior climb (at all altitudes)
      Superior visibility
      Smaller, and thus less easy to hit and see
      Cheaper
      K-14 gyro gunsight

      SIMILAR
      Similar turning circle, inferior if the P-38 uses airbrakes, but utility is questionable due to rapid bleeding of energy

      DISADVANTAGE
      Inferior transient performance (due to P-38’s boosted ailerons)
      Slightly inferior HP/lb (.23 vs .25)
      Greatly inferior armament
      No airbrakes

      SUPRISE – P-51 extremely decisive advantage
      Looking at all this, the P-51’s higher maximum and level speeds plus its better visibility and smaller size make it decisively better at achieving surprise without being surprised.

      NUMBERS – P-51 decisive advantage
      P-51 has a lower procurement cost than the P-38. Running costs are unknown, but I suspect the P-51 would have the advantage due to using only 1 engine.

      MANUVER – Draw
      P-38 has superior transient performance, similar/superior turning circle, and airbrakes, but the P-51 has a superior climb rate, level speed, and dive, allowing it to disengage at will.

      ENDURANCE – P-38 advantage
      The P-38 has greater range than the P-51, however, both fighters have extremely long range.

      RELIABLE KILLS – P-38 advantage
      The P-38’s armament is decisively superior to the P-51’s, but this is negated somewhat by the P-51’s K-14 gyroscopic gunsight.

      CONCLUSION: The P-51 is a superior fighter to the P-38 in all situations except in extreme range missions where the P-38’s extra range is relevant.

      • picard578 said

        “Inferior transient performance (due to P-38’s boosted ailerons)”

        I’m not sure about that. Boosted ailerons certainly improved maximum roll rate, but unless we have time to roll 90* and 180*, it is not really indicative of transient performance. Further, transient performance includes more than just roll onset. That being said, higher maximum roll rate does speak well of the P-38 upgrade.

        Agree with the rest.

  12. […] had any cases of aircraft lost due to the engine failure. In US example, twin-engined F-15 had higher rate of engine-related losses than single-engined F-16 despite F-16s overall loss rate being higher; […]

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