20

With the exception of the Panavia Tornado, fighters do not have thrust reversers. Why is this? Why does the Panavia Tornado have them?

fooot
  • 72,860
  • 23
  • 237
  • 426
Madhav Sudarshan
  • 5,699
  • 15
  • 46
  • 87

5 Answers5

22

Thrust reversal is a complex system (equals money) and it uses significant amount of fuel (also equals money). It is not a very efficient means to reduce the speed of a landing aircraft either, and other methods (e.g. brakes or drogue parachutes) are much better suited.

The biggest advantage of thrust reversal is that it cancels out the idle forward thrust working against the aircraft. Canceling out idle thrust isn't an issue on most fighters, as they have an engine nozzle that is open at ground idle to prevent any thrust from being produced. This nozzle probably also makes it a bit difficult to integrate Thrust reversals, but the Panavia Tornado proves it can be done.

Farhan
  • 29,390
  • 14
  • 112
  • 183
  • ... saving fuel on reverse thrust but always taking off with full afterburner... I don't think so – Jan Oct 25 '19 at 06:41
  • @Jan Rather than alluding what you think and downvoting, it is appreciated if you can provide some evidence. – Farhan Oct 26 '19 at 15:49
  • I can only speak for the civilian sector where a friend of mine who flies large commercial aircraft told me that their company instructed them to be light on the brakes and rather use full reverse thrust. You can always refuel but changing the brakes costs time during the turn around and thus a lot of money. Given the mission profile of military jet fighters - takeoff as quickly as possible, have air superiority at the target region by being as light as possible and having a higher thrust/weight ratio than the enemy - being economical is not top priority. – Jan Oct 27 '19 at 13:55
  • In short the answer should be: Thrust reversal is a complex system which adds unnecessary weight which reduces the effectiveness of the fighter. Leaving it away reduces the turn radius and improves handling qualities of the fighter. – Jan Oct 27 '19 at 13:57
  • It of course comes at the cost of having to change the brakes more often but better repair an aircraft after the fight than not having an aircraft after a fight. – Jan Oct 27 '19 at 14:01
13

It has nothing to do with cost or wasting fuel.

A military jet is notoriously designed to do the best it can, to hell with how much it costs. If expense of construction was a concern, they'd think it was ridiculous to build from exotic components just to shave a few pounds.

Fuel efficiency and fuel cost is only a concern in terms of being economical as possible in order to have the best range to attack the enemy, or to loiter on station on patrol. Wasting a little fuel on landing is inconsequential; why else would jet fighters have fuel dumps? It's common to jettison any few thousand extra pounds of fuel to get landing weight down, and it's also common to take extra fuel on from the tanker just in case. So you take three times as much fuel as you need to get back to base, then when you get there safely, you just dump it so you're light enough to land.

They don't include reversers because the extra weight and space they need would be better used for something else like fuel or avionics.

Military jets, especially fighters, are ridiculously expensive to operate, not just buy. Commercial aircraft, on the other hand, need to do things cheaply, with little maintenance and short turn-around times. Passenger aircraft and airlifters are far larger and heavier than fighters; that's why they need reverse thrust. A big enough parachute is a real pain to pack back up again, and replacing worn out brakes is expensive. A thrust reverser is extra initial expense, but it pays for itself.

Military large airlifters use thrust reversers to quickly unload and return for more, and to land on short runways; that's rarely a concern for a fighter. They may also need to turn themselves around for takeoff; while a fighter could be pushed by hand in a pinch, a C-5 Galaxy, not so easy. It's not surprising, in the few fighters that have a reverser (the Tornado and the Saab Viggen), landing on short or icy runways was a primary motivation, coupled with rapid turnaround, and the fact that parachutes are only effective at high speeds.

Camille Goudeseune
  • 11,726
  • 1
  • 42
  • 78
Kel Harper
  • 159
  • 1
  • 2
  • 6
    Welcome to Aviation.SE Kel! If you could do us a favor and break down your one giant paragraph into smaller ones... It's a little hard to follow as it's currently structured. – Jae Carr May 30 '16 at 02:20
  • I agree with this answer. Fuel is dirt-cheap compared to everything else about a fighter, including operating costs. The reason is weight and space. Fighters need to be as light as possible for the sake of maneuvering. They also prefer to be a small target. Yes, the answer should be broken up into smaller paragraphs. But I upvote because I agree with pretty much every sentence. – DrZ214 Jun 16 '16 at 05:12
11

Fighter aircraft are specialized tools optimized for a specific purpose: to destroy enemy forces (in the air and on the ground). Everything that is not vital to that mission is quite literally dead weight that reduces the performance of the aircraft as it relates to its specific purpose. Jet fighters are not required to "taxi back" on the tarmac, and simpler "speed brakes" are more effective at slowing down in flight.

Madhav Sudarshan
  • 5,699
  • 15
  • 46
  • 87
Skip Miller
  • 10,312
  • 28
  • 53
  • Fighter aircraft are specialized tools optimized for a specific purpose: to destroy enemy forces in the air and on the ground the latter I would call them bombers, though, not fighters. – Federico May 13 '15 at 15:51
  • 7
    @Federico: I think you will agree that many fighter aircraft have ground attack capabilities. – Skip Miller May 13 '15 at 15:56
  • that's the "fighter-bomber" mashup (of which the Panavia is a member). if we want ot be purists, no, fighters are not made to attack ground targets, if we include fighter-bombers then, instead, yes I agree with you. – Federico May 13 '15 at 16:03
  • ^ what???? No one calls the mighty Viper jet a fighter-bomber... It's a fighter. B-1, B-2, B-52 are bombers, hence the B designation. –  May 13 '15 at 17:07
  • @federico Who said anything about being a purist? The A-10 drops bombs, strafes, and blasts the insides* out of tanks with its GAU-8 gun. I asterisked "insides" in a fit of political correcness.... Is it a fighter bomber? No, its role is diverse enough that "fighter-bomber" doesn't really describe it well. – Skip Miller May 13 '15 at 18:24
  • @SkipMiller you will convene then that fighter does neither. – Federico May 13 '15 at 18:38
  • @TUMBLEWEED I do not know the Viperjet, but from a quick search is not even a military aircraft http://en.wikipedia.org/wiki/Viper_Aircraft_ViperJet – Federico May 13 '15 at 18:39
  • 1
    @Federico The F-16.. What every pilot calls it (unless you're a C-model driver). –  May 13 '15 at 19:11
  • @Federico: In the contemporary world, how many 'fighter' missions are flown against enemy aircraft? FTM, do ISIS, the Taliban, al Qaeda, &c even HAVE aircraft? – jamesqf May 13 '15 at 19:58
  • @TUMBLEWEED what the general public calls a "fighter bomber" and often a "fighter" is technically called a "multirole fighter aircraft". The F-16 is one such, so yes it's a fighter-bomber (which is an outdated term, but still in common use). While designed as a light air superiority fighter the F-16 quickly evolved into a multi-role aircraft with extensive ground attack capabilities, which is the primary role it performs for most operators. – jwenting May 15 '15 at 06:04
  • 1
    As long as we're splitting hairs about role designation, the correct terminology is actually attack or strike. For example the F/A-18 is a fighter attack aircraft, and is also called a strike fighter. Just like the air force has the F15E strike eagle. In summation, everyone is wrong, and we're all retarded for even caring. – Rhino Driver May 17 '15 at 06:33
  • @skipmiller i am a bit lost. A-10 is attack aircraft with close air support(CAS) role. Idgi what it has to do with bomber or fighter. – vasin1987 Jun 08 '15 at 18:12
  • The tri-service aircraft designation system, first off, is 53 years old this year; air combat has changed quite a bit in that time. Second, the "attack" specialization is primarily a Navy phenomenon; the USAF pretty much had only two classes, "Pursuit" (later "Fighter") and "Bomber". If it was capable of engaging another aircraft in a turning fight, it got a P or F designation, no matter what else it was used for (for example, the P-51 which did everything from bomber escort to tank plinking and CAS). This tradition continues today, with only one notable USAF "Attack" craft (the A-10). – KeithS Jul 30 '15 at 00:28
  • The Navy as stated was the side that introduced the attack specialization into the light-craft spectrum, having used it for a number of dedicated ground-attack aircraft starting with the venerable A-1 Skyrader and continuing through with its current "multirole fighter", the F/A-18 (which performs a similar role for the Navy as the F-16 does for the Air Force). The next airframe the Navy will put in operation is the F-35C, and there's no indication that the Navy will continue the "F/A" designation, so the "Attack" moniker may well die when the A-10 and F/A-18 are retired. – KeithS Jul 30 '15 at 00:40
1

The old Saab Viggen fighter also has thrust reversers. This was part of what made it so capable on short or improvised runways. Wasn't useful enough to keep in the Gripen that replaced it, that is a much more conventional 4.5 generation fighter.

Smartypants
  • 11
  • 1
-2

It is because they already have several ways of braking, so they don't need reverse exhaust.link This should explain to you the braking systems used by the f-16 instead of reverse exhaust. This jet you are describing may not have as many braking systems as a normal jet does so it uses reverse exhaust.

Simon
  • 31,213
  • 4
  • 141
  • 163
Ethan
  • 9,349
  • 24
  • 86
  • 141