Is there a advantage for having two engines over one ? Like the F-22 vs the F-35 one engine.

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emezeekiel@reddit

It has 2 engines for a few reasons, but it comes down mostly to the mission.

The f-22 mission is total and absolute air superiority. Meaning its only objective is to kill other planes, whatever the cost. Meanwhile, the f-35 is a multi-role aircraft designed to replace everything from the f-16 (Air Force) to the f-18 (Navy) to the Harrier (Marines) and do ground attack and close air support and air to air, at a cost reasonable enough that you can equip allllll your military with it.

So if you want to kill everything, from the f-35 to the latest generation enemy fighters, at whatever the cost may be, you will want 2 engines for:

the thrust, it’s essentially 2x the same engine as the F-35, so you can be sure to out run and out maneuver it (because it ALSO has thrust vectoring)
the reliability, if one engine dies you can bring your super expensive asset home

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Ange1ofD4rkness@reddit

Don't forget it's meant to replace the A-10 as well. But I didn't think the F-16 or F-18 fell under its list, that's news to me

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emezeekiel@reddit

What else did you think they’d be replaced by?

The air-to-air mission of the F-15 was replaced by the F-22, and the multirole F-16 will be the F-35, and like you said will also replace the A-10.

The sole Navy plane (F-18) and sole Marine plane are also being replaced by the F-35.

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HairyDog55@reddit

With your reference to F-14/ F-18 airframe, imagine the fuel/maintenance of the old F-4 Phantom!

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mspk7305@reddit

F-14 required about 50 hours of work for each hour of flight
I cant find anything on the F-15 but I assume it is somewhere between the F14 and F18
F-16 and F-18 required 5-15 hours of work per hour of flight
F-22's only reference for service/maintenance hours is from a reddit post claiming 30 per 1 but its likely bullshit and the F-22 is probably closer to the F-35 since it uses the same engine
F-35 is around 8 hours per 1 hour of flight

Yes but one factor they didn't consider, which I think is a complete failure of basic procurement, is the F14 looks cool as fuck.

Skunkworks need to get their shit together and figure out a stealthy, swing wing, twin engined machine of pure bad ass

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emezeekiel@reddit

Agree about the cool af but swing wing is a maintenance nightmare and a crutch that came from not having enough margin at slow speeds when the wings are in the config they need to be for supersonic flight.

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Expensive_Dig_6695@reddit

Why is the F14 swing wing a mx nightmare? I think that is bs. Don’t remember an a/c being down in our squadron for wing related issues. The inlet ramps were problematic, my memory is the awg 9 was always having issues. Awg 9 was the radar and all missile firing components, including the coolant system for all those electronics.

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WarthogOsl@reddit

If you listen to a podcast like the Tomcast, where they talk to a lot of F-14 maintainers, they hardly ever mention the wings as a source of pain for them.

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emezeekiel@reddit

Check this out, the wings were so annoying they abandoned some of its features.

https://youtu.be/R2tgByRCLzM?si=iWDerStZpSjA1gxS

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WarthogOsl@reddit

I'm not going to watch that whole video but I'm going to assume they're talking about the glove vanes. Those apparently were an issue possibly because of water intrusion, according to some of the maintainers I've heard talk about them (I heard one refer to them as water sponges). Notice that the Iranian Tomcats still have their glove vanes functional though.

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Back to the basic procurement failure premise when ‘Fat Amy’ is the more attractive choice

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BoringBob84@reddit

In that particular case, I agree. The USAF graded each company on three criterion:

technical compliance with requirements,
program management readiness, and
performance on past programs.

emezeekiel@reddit

That’s why I said essentially.

The f135 is the improved and uprated f119, yes, and in mil power they’re only 2,000lbf off in thrust, 26 vs 28k. So in 99% of use they’re basically similar.

Cheeze187@reddit

Inputs are made into the flight control computer. It decides the flight control movements. It's fly by wire, no amount of pulling on the sidestick will do any thing without power

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velociraptorfarmer@reddit

Yes, I couldn't remember if the F-16 was or not is all

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noir_lord@reddit

Was the first full production full digital fly by wire fighter.

Yeah, Hydrazine is one of those things in which one does not fuck with.

Theres gotta be a name for the universal law where this magic thing that is wonderful and amazing is also the most terrible thing to exist.

vermillionflour@reddit

Uh... the point of it is to help in an emergency. If you know when the aircraft is going to have an emergency ahead of time, you can plan even better and just ground it before it leaves...

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kingtacticool@reddit

Yeah I wouldn't think the F16 had much range in glide mode.

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SirLoremIpsum@reddit

https://youtu.be/7Unr5h_3y8c

Like you could use high test peroxide as a monoprop (and plenty of missions do), but it's also not exactly safe to handle, and it slowly decomposes on its own over time, so can't be used for situations where you need to store it long term (like ICBMs or long space missions).

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Dpek1234@reddit

hydrazine

I like calling this class of fuels cancer juices for a reason

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Fishy_Fish_WA@reddit

How much of the f-16s operating cost is handling the damned cancer juice?

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kingtacticool@reddit

I would think there would be a better, less dangerous way of doing that, but it lack the education to have a guess at what that might be.

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SpecialistPlastic729@reddit

During the early 1970’s the energy density of batteries was fairly low, meaning it would be a large and heavy solution.

If designed today I suspect a battery would be seriously considered if not selected for emergency power.

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FoxThreeForDaIe@reddit

If designed today I suspect a battery would be seriously considered if not selected for emergency power; the F-35 uses a Lithium Ion battery as part of its emergency power system

The F-35 uses batteries but the IPP (Integrated Power Package) is ultimately required as a backup to safely land the aircraft

The F-35's flight controls are very very power hungry. The batteries only do enough to prevent you from immediately falling out of the sky - to try and 'deadstick' it in to land you need to get the engine back up or IPP needs to be running

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Editing your comment to say "dual engine fighters" after people replied to you is dirty pool.

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TheAgedProfessor@reddit

the engine related loss rate for dual engine aircraft is effectively zero

Yeah no, that's not true at all.

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HortenWho229@reddit

I don’t know understand these people on online forums that just invent random shit and post it like they know what they’re talking about

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ic33@reddit

Plenty of multiengine aircraft-- not transports, but including some military aircraft-- have terrible single engine performance. They also have a higher risk of engine trouble (since they have multiple engines). And controllability and operations are complicated when you don't have all your engines.

Combine this with certification differences (a light twin is allowed to have a higher stall speed and landing distance than a single engine plane, so it has a much harder time landing survivably off-airport), and the data often shows a higher engine-related fatal crash rate for multiengine aircraft.

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ghjm@reddit

UPS 2976 just happened. And there have been any number of VMC rolls on takeoff.

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bobwehadababy1tsaboy@reddit

Good thinking!

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Youngstown_WuTang@reddit (OP)

3 engines 😍🥰

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MechanicalTurkish@reddit

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FormerFormerButerfly@reddit

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Youngstown_WuTang@reddit (OP)

3 engines are so COOL!

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biggles1994@reddit

Do you know what’s cooler than 3 engines?

8 engines.

*loud B52 screaming in the distance

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MechanicalTurkish@reddit

Do you know what's cooler than 8 engines?

10 engines.

Peacemaker enters the chat

six turnin' and four burnin'

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Twit_Clamantis@reddit

Neither. I just love that saying.

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albyzon@reddit

Supplies motherfuckers!

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ethereal_phoenix1@reddit

amature >! 68 engins!<

The warp field isn't generated by the warp core. It's generated by the warp coils. Those are in the nacelles.

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htomserveaux@reddit

Aktuly multi nacelle designs serve a variety of purposes. The most common being the four nacelle designs like the Constellation and Cheyenne classes which only used two at a time and were designed to extend their high speed endurance.

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MrD3a7h@reddit

The separation from the hull and from each other prevents the warp field from collapsing and keeps the starship inside the warp bubble.

Ackshually, this was part of a production rule where warp nacelles needed to have line-of-sight to each other in order to function. You can see how different space-faring species solved this problem in different ways. For example, the Romulan D'deridex-class uses nacelles integrated into the hull, but a large negative space in the center to preserve the line-of-sight rule.

Are you a friend of DeSoto?

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Psychological-Scar53@reddit

Tell me you are a virgin without saying you are a virgin..... Just kidding bro, don't need you to stun me with a phaser....

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nugohs@reddit

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Significant_Quit_674@reddit

Counterpoint:

Basicly all vulcan ship designs ever have a single circular warp nacelle

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EyebrowZing@reddit

I came across a great interview with Andrew Probert while looking into this.

Tyler: Do you know the origin of what have become known as "Roddenberry's Rules of Starship Design" -- the idea that warp nacelles have to be in pairs, and things of that sort. I understand that there were a set of guidelines. Do you recall the origin of those?

Probert: Gene specified to me, in fact, that starship warp engines operate in pairs... only in pairs because they're codependent. If you had one warp engine, you'd probably go in a circle, I don't know... (laughs) So in the same breath he negated the three-engined dreadnoughts along with the single-engined destroyers, on the edict simply that, to achieve warp drive, you had to have codependent warp engine pairs. As far as the line-of-sight requirement, that was my edict, that, in order to be codependent, the warp engines had to "see" each other, totally. I'm taking about the power combs, not necessarily the Bussard collectors but the bulk of those combs have an energy path between them. And then for other starships, just like in World War II, where all the nations had fighter aircraft that all looked different -- you know, a cultural distinction between, say, a German aircraft and an American aircraft or a Japanese aircraft -- they all operated in the same way having the same basic components of wings, body, and engine, so I applied that thinking to the alien ships I designed as well, so the Ferengi ships, and Romulan Warbirds, have twin warp engines that have to see each other in order to operate. Even my shuttlecraft having a very shallow clearance, still see each other. That's why designs like the Romulan scout ship, where the engines cannot see each other, aren't consistent. There are also some cool Starfleet designs like the Nebula Class ships, but their warp engines cannot see each other. Even those runabouts ignore that ruling which messes up the continuity. Science fiction in particular NEEDS to be consistent. If you negate that,...it all falls apart.

Tyler: I recall another rule about the nacelles being visible from the front...

Probert: That's probably something that I came up with, simply to allow for clearer access to free hydrogen that those collectors have to... collect.

I am going to ask my wife to take my virginity again tonight.

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Mo_Steins_Ghost@reddit

I met, interviewed and got to know Andy (he was the subject of a high school project I did and eventually I met him about ten years later).

One of the things I miss is that all the Pasadena ArtCenter grads had in common is their focus on real world industrial design principles. Andy always said if you design something that looks how it should work then people will suspend their disbelief easily.

Alas, he also knew that in the end the model makers and set designers always win because they get the design last before it goes into production.

He won very few battles, the wood tactical rail being one of them: gene didn’t have much control at all beyond season one of TNG but one thing he defended was Andy’s design here because it kept with the idea that the Ent-D is a living space where crew and their families will be living for very long periods. So everything needed to be less militaristic and more livable.

A battle he lost was the Aztec hull patterns: no ship of that size would have hull fabrication panels so large (where would you build them? How would you transport them) they could be seen from the distance you’d have to be in order to see the entire enterprise (original movie refit). It would appear smooth, just like the space shuttle does until you get up close.

It's conceptually inspired by the TNG episode Lower Decks in that it focuses on low ranking officers not the command crew.

It's set on the California Class ship Cerritos, part of a new generation of ships built after the Dominion War to replace the ancient Miranda/Soyuz class of smaller starships. They often get missions like Second Contact, going back to a planet that someone else did the much more exciting First Contact and just seeing how things are going.

It's an amusing series and it uses call-back references for comedic value in a kinda fourth-wall-breaking way. Like they discuss who is the most badass maverick space adventurer, was it Okona or Roga Danar. The reference isn't really relevant to the plot it's just character banter but if you know who those people are it's an extra level of amusement.

They also try to 'fix' some issues with the logic like there's an episode where someone installs new space-rocks behind a panel on the bridge. Because often when the ship gets damaged an explosion sends mysterious pieces of rubble across the bridge but why are there rocks on a space ship? The engineer explains that the asymmetric shape of the silicon nodules deflects fluctuations in the warp field, or something like that. But it's just a joke to explain a bad choice by set designers in the 1980s. Personally I prefer the fan explanation that the plasma in the EPS conduits is made of silicon atoms which oxidise into silicates and form the rocks spontaneously when the EPS conduits are ruptured.

They have a LOT of call backs and some people might find it cheesy but it's a comedy anyway and it's coming from a place of respect. There's an episode with a multiverse portal and a dozen different copies of Harry Kim then they're shocked to discover this new Harry Kim is a Lieutenant not an Ensign! The first time in all the multiverse that a Harry Kim has been promoted.

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PigSlam@reddit

Also I believe that after having typed that sentence I have officially regained my virginity

It was fan blade disk failure, on United 232. The disk is what the blades are dovetailed into. Manufacturing defect (that was detected during QC!) was ignored as the faulty disk wasn't scrapped, and was subsequently used in a CF6 engine on the accident aircraft. Thermal stresses eventually formed a crack which progressed to the point of catastrophic failure: uncontained bursting of the disk, throwing shrapnel through all 3 hydraulic systems.

Miraculously the crew managed to continue flying the aircraft and almost landed it.

I suspect the UPS crash may involve similar findings as the photos of the engine show no fan disk, with Kevlar engine casing reinforcement wadded up in the first compressor stage. Single or multiple blade failure events are rarely uncontained, but for the entire engine and pylon assembly to separate from the aircraft suggests an extremely catastrophic event, and the fact that the engine caused severe damage to the wing instead of separating "cleanly" like AAL 191 suggests that rather than accelerating away from the wing as it would under power, it instead fell onto the runway and bounced into the underside of the wing.

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ednw1111@reddit

Souix city plane crash , it was the tail engine that did the damage to the hydraulics. Managed to almost land it just using the engine throttles, then ( I think ) a gust of wind caught it https://youtu.be/sWkU6HRcOY0?si=ZA54yKP0kk13k-A6

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Just-Yogurt-568@reddit

Apparently they couldn’t even manage to do as good as this in the simulator attempts. Pilots were heroes.

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DaBingeGirl@reddit

One of the passengers told Dennis Fitch he killed her husband. I felt so bad for him when he said that, from his voice it sounded like that's what he focused on, not the fact that he saved so many lives. He and the other pilots did an exceptional job. I understand that woman was grieving, but it seemed incredibly cruel considering every sim attempt failed.

My favorite thing about that incident is Captain Haynes accepting Fitch's help. He knew they needed all the help they could get and didn't let his ego stand in the way.

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TheAgedProfessor@reddit

Still have no idea how passengers walked away from that.

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BreadUntoast@reddit

DOD frantically figuring out a way to turn the TriMotor into an AMRAAM bus

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Youngstown_WuTang@reddit (OP)

Dammit Germans are always a step ahead

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What_Chu_Talkin_Kid@reddit

The Big Daddy Dornier DO-X has entered the chat
😸

Dornier DO-X has entered the chat

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Normal_Ad_2337@reddit

A step ahead if it works.

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Potential-Dog1551@reddit

I had one of these make a low pass in handy and then come in for a landing, I thought at first glance that it was a butched up version of the tri-motor until I got a little closer. Really cool old planes.

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JBaecker@reddit

📎

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deleted_by_reddit@reddit

[removed]

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AutoModerator@reddit

Submission of political posts and comments are not allowed, Rule 7. Political comments can result in a ban.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

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linux_doggo@reddit

i miss tri-jets

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VideoLeoj@reddit

I took my grandmother for a birthday flight on the EAA Ford Tri-Star when it was in town a few years ago. It was SO COOL!! What a neat machine! We flew around the area at about 1500’ for about 20min.

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dastardlyninjas@reddit

Ive ridden in one of those old ford tri-motors- they have all the comfort of an old school bus inside lol

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Olivrser@reddit

Ford trimotor is amazing

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lacarth@reddit

I fondly remember a time where I was working the only 24-hour gas station in my remote town, I'd always find schizophrenic posts on the bulletin board. One of the common topics was about how 3 engine planes were safer because they were more holy because of the Holy Trinity. God, I miss those posts. I had a collection, at one point. I even found one of the same person's posters at a gas station over an hour away.

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MakerManICT@reddit

I was gonna say falcon 900 sure as heck said lets add one more just for funsies. They just wanted am excuse to make a neat s duct. Fun fact, instead of using and electric pump for potable water the use bleed pressure form the no1 engine to pressurize the water tank.... leave it to a french engineer!

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Melech333@reddit

Savoia-Marchetti S.71 enters the chat

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giggidygiggidyg00@reddit

The tri jet Falcons are my absolute favorite. I started working at Dassault Falcon Jet in Little Rock a month ago and I love it.

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Complex_Sherbet2@reddit

Maybe there is one stowed underneath your seat.

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SpeedBlitzX@reddit

Isn't China developing a fighter jet with 3 engines? Can't imagine the range would be very far, with three engines.

I think it's supposed to be the J-36

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Youngstown_WuTang@reddit (OP)

I mean to a noob like me, 3 engines sound better than 2 lol. Why not 3 engines fighter jets ?

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Dr_Hexagon@reddit

Chinese J-36 "stealth" fighter appears to have three engines.

https://www.twz.com/air/chinas-massive-j-36-tailless-fighter-gets-major-design-tweaks-with-second-prototype

No one is quite sure if its a heavy fighter or a light bomber / ground attack vehicle. It's also possible they have to use three engines because they can't make engines inside China powerful enough for it's weight with only two.

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Tupcek@reddit

every engine means more mass (thus less maneuverability and worse performance), but better reliability.
So the question is, how much performance are you willing to give up for reliability

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SilverDad-o@reddit

I'm not sure the word is "reliability" so much as "survivability." If: a) a fighter has two engines, but - all things being equal - would cancel a mission, patrol, or training if one of its two engines is malfunctioning, then its reliability is actually lower with two engines; b) a fighter has only one engine and it has a serious malfunction/damage while on a mission, patrolling, or training, it will need to land ASAP and, unless it's fortuitously close to a friendly airport, it will be destroyed/lost, reducing its survivability.

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FoxThreeForDaIe@reddit

I'm not sure the word is "reliability" so much as "survivability."

Nope. It's 100% about reliability

A missile hitting a jet is going to f*ck up a lot more than just an engine, including likely flight-critical things like hydraulic lines and what not

The part every non-pilot is missing is that a two-engine jet inherently has fewer points of failures

In the F-35, an engine oil problem becomes a Land as soon as POSSIBLE emergency. In an F/A-18, an engine oil problem is as Land as soon as PRACTICAL problem.

Very different actions and urgency

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GodsFavoriteDegen@reddit

I once asked a professional pilot (as in, passenger jumbo jets) relative of mine how far a two engine plane could fly on a single engine.

"All the way to the crash site."

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Mac-Daddy-63@reddit

I remember reading a report somewhere in my past where the Navy did a study on 1 v 2 engines. The take away from that is the survivability rate of having two engines vs one was statistically insignificant. The thinking also was that whatever weapon took out one engine, odds were it would take out the other too. And as far as engine failures is concerned, the MD-11 crash is not the only crash I know of where one engine’s failure took out other engine. One in particular was a C-141 taking off. In that event, the number two engine turbine disk failed. It took out the number one and number four engines with shrapnel. The only reason number three wasn’t destroyed is the aircraft fuselage protected it from the shrapnel: though there were several holes in the fuselage. The only reason the plane survived is those Pratt and Whitney TF-33’s were beasts of engines. They over boosted the engine, did a minimum pattern and got back on the ground. Then some maintenance guys had to come out and replace four engines.

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SilverDad-o@reddit

Interesting. Thx for sharing.

Given how modern SAMs/AAMs work, the odds of a missile strike taking out one engine but not destroying another critical system and/or the second engine are low. SAMs/AAMs usually shred the airframe, and the pilot/crew have mere seconds, at most, to eject. (There are some exceptions where the aircraft and pilot survived a SAM hit - e.g., two A10s in Iraq, 2003).

The survivability factor is probably more plausible in non-combat scenarios involving an inflight failure of one engine where the pilot (and aircraft) can make it back to base/aircraft carrier without having to ditch, crash land, or eject.

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DarthJahona@reddit

Weight mainly. You add more engines, the aircraft gets bigger and heavier and you lose maneuverability.

Youngstown_WuTang@reddit (OP)

It's so cool !!!

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slinger301@reddit

BUFF has entered the chat

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Temporary_Cry_2802@reddit

I'll raise you the B-36D with it's 10 engines "6 turning and 4 burning" or "Two turning, two burning, two smoking, two choking and two more unaccounted for"

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Doggydog123579@reddit

hits joint

but what if it had more?

AcePsych247@reddit

Inherently unstable actually. As engine reliability has gone up, the need for extra engines has gone down

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C4n0fju1c3@reddit

There's only one modern example I can think of which is that Chinese medium range fighter bomber thing. (Chengdu J-36) the reason they went with 3 engines is that the ones they have available at the moment are a bit underpowered. Basically they currently lack some of the advanced metallurgy/manufacturing techniques that are available to the US defense industry. They'll get there, have already advanced WAY past the Russian-designed engines they were originally building licensed clones of.

To answer your question: It's comes down to tradeoffs. More engines = more redundancy and more thrust. However more engines also = more weight, more necessary internal volume, and more fuel consumption. Commercial aircraft with nacelle-mounted engines don't have the internal volume issue and are rocking high-bypass turbofans... But that's a bit of a different equation.

Maintenance is it's own issue. Removing/swapping the single engine on aircraft like the F-16 is surprisingly straightforwards (for a fighter jet). I can't even imagine what the process is for getting at the central engine on the J-36.

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julius_sphincter@reddit

The reason they went with 3 engines is that the ones they have available at the moment are a bit underpowered.

I mean, we don't REALLY know why they went with a 3 engine layout. I think it's fair to speculate that's a reason but we can't know without understanding what the primary function of the J-36 will be. Plus the WS-15 will be at least comparable to the engines powering the F-22 and it's safe to assume the J-36 would at least be outfitted with those

If the J-36 really is just intended to be a long range, stand-off stealthy missile truck then depending on payload maybe they'd need a 3-engine layout even with modern US engines.

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C4n0fju1c3@reddit

Hmm... That's fair. In my mind I think of the B-21 as a modern example of a long-range, stealth, stand-off missile truck. The B-21 isn't a supersonic design though. Maybe the Chinese are trying to develop something like a stealth B-1 lancer while circumventing the need for a large aerial refueling fleet? It's a very interesting aircraft, and I'll be stoked to learn more about it.

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julius_sphincter@reddit

Yeah that's a good point about the B-21 comparison. Could be something like where the B-21 is viewed in a hybrid role with it's other function strategic/medium bomber, the J-36 is a hybrid with the other function being interceptor. Which makes sense - America is going to see the B-21 as a penetrator aircraft prioritizing all aspects of stealth over enemy airspace while the J-36 is likely to be used over Chinese territory where rapid response to a situation is going to be prioritized over all-aspect stealth

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julius_sphincter@reddit

China is apparently building one

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SirLoremIpsum@reddit

I mean to a noob like me, 3 engines sound better than 2 lol. Why not 3 engine with fighter jets?

Why 3 man? Why not 4?

Why not 6?

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brwonmagikk@reddit

Chinese are flight testing a three engined stealth airframe as we speak. Probably some anti shipping strike platform but it looks like an absolute bus

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cbg13@reddit

Each engine you add doubles the maintenance needed, amongst other things

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HealthyZone4794@reddit

Uhmm, no. If you add a second engine to a single then your maintenance needed will double. Add a third, maintenance goes up by 50%. Adding a 4th to 3-engine aircraft will increase demand by 33%.

That's just how math works.

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cbg13@reddit

While youre not wrong, you're just kind of a pedant. It was aj off hand comment about going from 1 engine to 2 doubling maintenance, chill out bro

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skippy_smooth@reddit

The MD-11 Fighter would be awesome

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notawildandcrazyguy@reddit

Well at some point you have to account for weight, aerodynamics, and other important things like fuel. If all you cared about was safety and redundancy then yeah 10 engines or 100 engines would be good. At some point tradeoffs are necessary

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MarcellusxWallace@reddit

Something to do with weight, my little pea brain tells me, based on absolutely nothing.

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MD11 enters the chat

… too soon eh

Fun fact, they used to require at least three for cross ocean flights for specifically this reason.

And why modern twin engine airplanes can do an entire flight, gate to gate, with one engine.

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Kiwigavin@reddit

“Because they don’t make them with six”, said every jumbo pilot everywhere.

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mundotaku@reddit

Actually, that is why passenger planes had 3 engines in the 70s and 80s. Quite literally.

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Affectionate_One_700@reddit

Until ETOPS!

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Affectionate_One_700@reddit

Twelve is even safer.

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olivia_iris@reddit

I can see where this is going. Someone wheel out the N1.

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Opaque_Cypher@reddit

That’s what UPS thought too

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Otheus@reddit

4 is ideal

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dumptruckulent@reddit

Why not 4?

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Feisty_Parsley_83853@reddit

Yes! The the ups plane in Kentucky.

And if it was single engine, they would never have gotten to even attempt an approach. It's a shitty situation that was recoverable most of the time, but single engine, that would have been 100% a loss

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SpecialistPlastic729@reddit

Not true. I know of at one, unsuccessful attempt

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FoxThreeForDaIe@reddit

Not true. I know of at one, unsuccessful attempt

Know of one what? A flameout approach to a carrier? Or single engine approach?

If it's what you posted elsewhere, the F-14 could be recovered single engine to the carrier. Flying a shitty approach - such as being on-speed but at excessive AOB (which kills your lift) - or being too heavy for single-engine recovery at that time, could yes, cause you to fail your approach.

Again, single-engine aircraft that lose that engine would never have been able to even attempt a landing in the first place. Period.

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SpecialistPlastic729@reddit

I’m not aware of a deadstick landing attempt on a carrier.

I would not call the approach shitty, although the AIB did fault him for the loss of the aircraft.

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Expensive_Dig_6695@reddit

That was a really bad coincidence. The overshooting wrapped up approach coupled with an engine stall at low altitude ~2-300’.

I have 1200 hours in the A. Always did zone 5 burner cat shots. It was a long time ago. 87-91.

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SpecialistPlastic729@reddit

Props! I know a guy who ended up in 202 because he “allowed a sink rate to develop which could not be arrested in the available altitude”

Long story. On the cat shot, his left engine fodded. They jettisoned stores and managed to climb away, even though it was a heavyweight launch. And then burned off fuel and was the last aircraft to be recovered in the cycle. But as he turned to final they started a descent and even though he put it right at the max AOA for single engine flight, it was obvious they were gonna hit the water so they punched out.

I don’t think he would have gotten in as much trouble if he didn’t save it after the launch.

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MillionFoul@reddit

Twin engine fighters are more likely to experience an engine-related Class A mishap than single engine fighters.

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FoxThreeForDaIe@reddit

How is this being upvoted?

Twin engine fighters are more likely to experience an engine-related Class A mishap than single engine fighters.

Dude, where did you get this pure misinformation? Absolutely 100% verifiably false - and we have as close to apples-to-apples data to back this up;

https://www.safety.af.mil/Portals/71/documents/Aviation/Engine%20Statistics/F-15%20ENGINE%20-%20RELATED%20CLASS%20A%20FLIGHT%20MISHAP%20RATES.pdf?ver=NFVV64LAZJk9bz1_Sqlm8w%3d%3d

https://www.safety.af.mil/Portals/71/documents/Aviation/Engine%20Statistics/F-16%20ENGINE%20-%20RELATED%20CLASS%20A%20FLIGHT%20MISHAP%20RATES.pdf?ver=c5-t1D6mi-cVNceCqyQEAg%3d%3d

Same era, largely same engines:

F-15: total 13,646,734 engine flight hours, 35 Class A's, 0.26 engine-related mishap rate

F-16: total 11,365,923 engine flight hours, 127 Class A's, 1.12 engine-related mishap rate

The single engine fighter had a FOUR TIME greater engine-related Class A mishap rate

I don't know where this "single engine is more reliables/after than two-engine" BS started online, but this goes against basic industrial and systems engineering and math

We parallelize the hell out of systems because reliability of PARALLEL systems is measured in 1 - (Q)^n where Q is failure rate and n is the number of parallel systems

So going twin engine is not only safer, it is exponentially safer as borne out by the F-15 vs. F-16 example where two engines doesn't reduce by mishap rate by 50%... it reduced it to 25%

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MillionFoul@reddit

Interesting, I 100% agree with you conclusion based off of your data, yet I know for a fact I've seen the exact opposite data from somewhere. Perhaps the Navy is particularly good at blowing their engines up? I remember reading a paper about it not very long ago, but now I can't find it.

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FoxThreeForDaIe@reddit

Interesting, I 100% agree with you conclusion based off of your data, yet I know for a fact I've seen the exact opposite data from somewhere. Perhaps the Navy is particularly good at blowing their engines up? I remember reading a paper about it not very long ago, but now I can't find it.

I've been to Navy Safety School. I'm pretty damn confident that data doesn't exist. The Navy has historically strongly preferred two engines because everything from engineering analyses to mathematically modeling to systems engineering to combinatorics to our own historical safety record has proven that two engines is more reliable than one. It's the same reason airlines aren't rushing to single engine anytime soon, even if modern motors are extremely reliable

You're probably thinking of issues where a catastrophic outside input - like FOD on a critical time, like during a catapult shot - can end up wrecking two motors just as easily as one motor.

The other thing you might be thinking of is that losing an engine in a multi-engine aircraft DOES make the plane harder to fly/recover. This is why we have single-engine and multi-engine ratings on the civilian side and why single-engine flying gets trained to in multi-engine aircraft on both military and civilian sides. So yes, there are mishaps related to not flying a multi-engine aircraft correctly when it loses a motor, particularly with asymmetric thrust

The part everyone else misses is that the single-engine aircraft in that same scenario would have likely been a complete loss to start with. You're not going to 100% safely recover a two-engine jet that loses a motor every single time, but the rate of success is magnitudes higher than the single-engine jet that loses its motor.

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chanman819@reddit

It might be botched interpretation from general aviation, where casual pilots are more likely to end up behind the added complexity of a light twin and end up in more dangerous scenarios than with light singles.

An engine out might see the pilot of a twin pilot departing controlled flight from poor handling of asymmetric power compared to the pilot of a single, who will definitely need to make a forced landing, but is less likely to lose control of their plane.

This article is over twenty years old, but discusses that pendulum swing of 'common knowledge'

https://www.flyingmag.com/wrong-worry-twins-versus-singles/

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FoxThreeForDaIe@reddit

This article is over twenty years old, but discusses that pendulum swing of 'common knowledge'

Yep and unfortunately people still misapply the data to mean that twin-engine is inherently no different than single-engine

We have separate multi-engine ratings from the FAA and we have multi-engine training in the military for that reason. Multi-engine will have considerations single-engine won't

But as the article states, there are numerous scenarios a multi-engine can encounter that are unreported as uneventful that in a single-engine likely would have resulted in loss of aircraft:

And many competent pilots land twins uneventfully every year after an engine failure, but those incidents are never reported because they are not tracked by the FAA, NTSB or anybody else. A piston twin can’t continue safely to a runway under every circumstance, but except for the moment or two during some takeoff conditions, a safe landing on a runway should almost always be possible.

Thankfully, the Air Force publishes its engine-related mishap lists, and the F-15 and F-16 data is pretty damn conclusive. Same eras (so we can disregard safety cultural shifts over that time), same engines(ish), lots of data (11+M engine flight hours per) and it shows a four times higher rate of engine-related Class A's for the F-16.

Which completely jives with the fact that with two engines, the probability that both motors are lost is exponentially harder to have happen than losing a single motor (drives me insane reading these comments on here misapply statistics... like two engines means the odds of BOTH motors going out at the same time is not double the rate of a single, but rather a lot less)

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l3ubba@reddit

RIP Goose

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stormwalker29@reddit

That was more a problem with the engines themselves than with having two of them.

Aside from the well-known compressor stall issues, the TF-30's did not like rapid changes in the throttle setting. Which, aside from being a fairly common event for fighters, it also tends to come into play during emergency scenarios, and thus complicated recovery from engine-out.

The F-14 B and D were much better behaved.

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Expensive_Dig_6695@reddit

I probably had 6-7 compressor stalls in my 4 years. Never in a loaded up situation. It was usually high altitude pulling throttles back. Fuel control unit issue. The “flat spin” never was mentioned to be caused by an engine failure. AFAIK…The airplane for all its funky flight controls was fairly honest. It let you know you were about to stall.

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stormwalker29@reddit

That last part - the plane letting you know when you were about to stall - is one of the most common things I have heard F-14 pilots say about the Tomcat. Nearly all of them I've heard from talk about how communicative the airframe is, if you pay attention to it.

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MikeyPlayz_YTXD@reddit

It sounds like you have some awesome stories to tell. The Tomcat was such a beast man. It’s my favorite fighter of all time.

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dougmcclean@reddit

It's actually worse in a significant number of cases. My ground school class personally witnessed the immediate aftermath of one such case.

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FoxThreeForDaIe@reddit

It's actually worse in a significant number of cases. My ground school class personally witnessed the immediate aftermath of one such case. I don't know about in fighters, though, can't speak to that.

Like what?

There are WAY more "Land As Soon As Possible" emergencies in an F-35 than an F/A-18, for instance. You will always have less redundancy single engine - period.

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dougmcclean@reddit

Coming down regardless, but how you come down makes a big difference in many aircraft. Probably less so in things with ejection seats.

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FoxThreeForDaIe@reddit

Sure, but don't misconstrue "misapplies wrong rudder" with the fact that there are many uneventful engine-out issues in multi-engine aircraft that go unreported. To say nothing about the fact that an engine problem can be a precautionary issue in a multi-engine aircraft versus a race-against-time issue in a single-engine

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Mundane_Republic1804@reddit

This may have changed but a speaker at a conference I went to about 20 years ago stated that modern engines are so much more reliable than early ones that failures tend to be catastrophic, taking out any adjacent engine.

For example, early F-4 Phantoms could (and did, on many occasions) experience compressor stalls under "spirited" maneuvers so having two was fantastic because there was a chance that one would not stall, or if both stalled you had better odds of restarting at least one.

Modern engines do not have this problem.

They, like earlier engines, do have the rare problem of undetected metallurgical flaws causing explosions, sending shrapnel into the other engine. In this case a second engine would be of limited utility, because it and its support equipment are likely to have been destroyed as well.

All of this may be bullshit. I am not a pilot; I am an aerospace engineer who works on space not civil or military aviation.

But it is what I was told a long time ago.

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FoxThreeForDaIe@reddit

All of this may be bullshit. I am not a pilot; I am an aerospace engineer who works on space not civil or military aviation.

That speaker is full of shit.

Catastrophic engine losses as a whole are rare - especially that catastrophic to damage another engine. Modern FADEC'd motors will go so far as to shut down the engine entirely to prevent catastrophic engine losses.

There are a wide range of issues that are not catastrophic that can affect an engine that would be considered routine in a two engine jet to mitigate that can be hair rising single engine. Oil issues won't be catastrophic immediately, for instance, but in a single engine jet that might give you X minutes of flight time remaining. Two engine jet? Might be a "watch what happens to the affected engine, land when you can"

IOW, there are a LOT of engine emergencies that are benign in a two engine jet (due to redundancy) that in a single engine jet result in a land as soon as possible.

Two engines also allow you to put in fire suppression systems to shut down one motor to prevent catastrophic loss of the fighter. In a single engine aircraft, your choices are to shut down the motor or punch out - the latter of which will happen if

More likely is taking FOD - foreign object debris/damage.

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MillionFoul@reddit

Twin engine fighters are more likely to experience an engine-related Class A mishap than single engine fighters.

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FoxThreeForDaIe@reddit

Twin engine fighters are more likely to experience an engine-related Class A mishap than single engine fighters.

Dude, where did you get this pure misinformation? Absolutely 100% verifiably false - and we have as close to apples-to-apples data to back this up;

https://www.safety.af.mil/Portals/71/documents/Aviation/Engine%20Statistics/F-15%20ENGINE%20-%20RELATED%20CLASS%20A%20FLIGHT%20MISHAP%20RATES.pdf?ver=NFVV64LAZJk9bz1_Sqlm8w%3d%3d

https://www.safety.af.mil/Portals/71/documents/Aviation/Engine%20Statistics/F-16%20ENGINE%20-%20RELATED%20CLASS%20A%20FLIGHT%20MISHAP%20RATES.pdf?ver=c5-t1D6mi-cVNceCqyQEAg%3d%3d

Same era, largely same engines:

F-15: total 13,646,734 engine flight hours, 35 Class A's, 0.26 engine-related mishap rate

F-16: total 11,365,923 engine flight hours, 127 Class A's, 1.12 engine-related mishap rate

The single engine fighter had a FOUR TIME greater engine-related Class A mishap rate

I don't know where this "single engine is more reliables/after than two-engine" BS started online, but this goes against basic industrial and systems engineering and math

We parallelize the hell out of systems because reliability of PARALLEL systems is measured in 1 - (Q)^n where Q is failure rate and n is the number of parallel systems

So going twin engine is not only safer, it is exponentially safer as borne out by the F-15 vs. F-16 example where two engines doesn't reduce by mishap rate by 50%... it reduced it to 25%

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rawwwse@reddit

This is the key point. Something I completely misunderstood until recently—talking to a pilot with a twin engine plane.

Basically… It can’t fly safely with only one engine, and now—that there are two—he’s twice as likely to have engine problems ¯\_(ツ)_/¯

Advantage: Much faster! (In this case anyway)

Now you have to weigh the risk of one engine failing in a way takes out both engines (which if that was the only failure mode makes 2 engines half as safe) vs single failures.

Where do people keep pulling this nonsense from? Has the internet discourse about this taken away a basic understanding of systems engineering and industrial reliability>

One engine failing that catastrophically almost never ever happens. It almost always requires outside input (i.e. FOD or a birdstrike) and even then, it rarely causes damage to the other engine.

Catastrophic destruction of an engine is so rare it isn't even worth considering.

What is actually far more likely to happen, statistically speaking - and in practice - are single points of failure that in a single engine force you to take drastic actions sooner. For instance, an ENGINE OIL caution in an F-35 becomes a Land as Soon as Possible emergency. In an F/A-18, it's a Land as Soon as Practical emergency.

The F-35 has WAY more "Land as soon as possible" emergencies than the F/A-18.

You have significantly more single points of failure in a single engine jet, to include things like cooling lines, fuel lines, etc. or else you're just adding weight for redundancy that is inherent in a two engine jet

Hell, the F-35 has a single engine running essentially two generators - and the IPP is an entire backup system that has to provide electrical power if you lose your motor. The F-16 has the main generator, standby generator, and emergency generator.

That's three generators compared to two generators - one per engine - on the F-15, F/A-18, and F-22.

DouchecraftCarrier@reddit

Gun combat was barely relevant fifty years ago and is near meaningless now.

I don't disagree with your point but it's worth pointing out that they had to build a gun pod for the Phantom because it was designed without a cannon and crews ended up losing fights in Vietnam because they ran out of/couldn't use missiles and didn't have anything else to use.

deleted_by_reddit@reddit

[removed]

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AutoModerator@reddit

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These stand-off missile platforms aren't ever meant to come into visual range, but if they're both stealthy, what happens when one happens to get a ping from Mk 1 eyeball?

Hypothetically.

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ThePrussianGrippe@reddit

They learned that lesson in ‘Nam.

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Like_a_warm_towel@reddit

This was also said during Vietnam.

1II1I1I1I1I1I111I1I1@reddit

F-15EX is a missile truck, different role. Its a small B1-B.

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NotGolden_Aviation@reddit

Well, first would be the cost; the F-35 is outstandingly expensive to operate on its own, and now multiply it twice cos you strapped another engine to it.

Secondly, with the lift fan system, one powerful engine is required, as it’s nearly impossible to perfectly synchronise the thrust in two engines (this is crucial for precise VTOL on a carrier for example).

Lastly, it would be too big for the aircraft carriers. As I mentioned, the lift fan system requires one big engine. Now, if you were to add a second beast to it, you would need a fuselage at least 150% of the current size (not to mention the current one is already MASSIVE) thus making the replacement for the Harrier appear pointless.

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Baratacus619@reddit

Clearly you have never seen Robotech. I know for a fact that an F14 can go into VTOL mode by switching to Guardian configuration.

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DeltaV-Mzero@reddit

I keep writing my congressmen telling them we should do this because “it would be sick as FUCK” but nobody has any vision these days

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Inceptor57@reddit

Two reasons:

Cost as others have mentioned.
For the STOVL configuration in the F-35B. The F-35B needs to be able to hover to land, and a one-engine configuration was a lot easier for this task than a two-engine configuration.

The J-50 is bigger still, and the J-36 is ginormous. I'm not surprised when people initially thought the J-36 was a bomber (it probably is, to an extent).

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Rexpelliarmus@reddit

The J-20 is significantly larger than even the F-22 which is why its range dwarfs what the F-22 can manage even with two external fuel tanks.

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King_Roberts_Bastard@reddit

Russian jets are much bigger than western jets. They need the extra fuel and range to cover the vastness of Russia.

Hilarious that you even question it. Damn near the only thing the Pacific Fleet does presently is FONOPs around China. The distance between Taichung City, Taiwan and Quanzhou, China is only \~230km and the USN sails through the Taiwan Strait constantly.

https://www.nbcnews.com/world/asia/china-condemns-sailing-us-british-warships-taiwan-strait-rcna230977

The USS Higgins and HMS Richmond were there in September and it only made the news because China complained about it. It happens constantly and never makes the news because nobody gaf.

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Rexpelliarmus@reddit

Yeah, look up when the last time an actual carrier strike group sailed through the Taiwan Strait instead of one or two irrelevant ships.

Hint: It has been nearly two decades.

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1II1I1I1I1I1I111I1I1@reddit

You said "the USN" not "a USN CSG". The CSG has better places to be, usually in the East China Sea, where China can still see them anyway.

And even then, if China was going to launch missiles at a USN ship they'd absolutely fire at the Higgins. An Arleigh Burke is a very high value target, its not an irrelevant ship. An irrelevant ship would a patrol boat like the ones China rams into the PCG every other month. AEGIS-equipped ships are critical to the strike group's safety, China would destroy one at the earliest opportunity if that was their intention. And if the U.S. thought that was their intention they wouldn't be sailing them nearby.

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Rexpelliarmus@reddit

No, they wouldn’t. If China were to fire and use their element of surprise, they’re not going to fire at a single ship.

And they’re not likely to use up their PLARF stockpile on a single destroyer. They’d just send out an SSN or one of their own ships or planes to intercept.

Furthermore, I think it’s fairly obvious that given the contact of this discussion that the only relevant thing that’s been referred to is a USN carrier strike group.

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aeneasaquinas@reddit

The USN doesn’t even sail within 1000 km of Chinese shores because of the saturation of PLARF missiles now

The USN literally has sailed within 100 miles of the shore in the past couple months. Stop making crap up.

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CerealLama@reddit

and mid air refueling if necessary

This is the really important point. Russia and China each have under 30 mid-air refueling aircraft. The US has over 600.

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crazyfoolguy@reddit

NKAWTG 🤙🏽

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brwonmagikk@reddit

They need the range because they are severely lacking in IFR capabilities.

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Rexpelliarmus@reddit

China doesn’t need it given any conflict is going to happen well within their sphere of influence. The US cannot sustain a large number of sorties with tankers the same way it could if its fighters could get there on their own.

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factoid_@reddit

Yeah and you needed an entire squadron of them plus escorts to actually hit anything because the bombs were unguided and the Norden bomb sight didn’t work for shit

One f15 could have complete a whole b17 squadrons mission with little to no support

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factoid_@reddit

And if you sent a fully loaded f15ex to do a mission the a squadron of B-17s would have been assigned it would absolutely outperform simply on the basis of its targeting capabilities.

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fffjayare@reddit

https://www.reddit.com/r/aviation/comments/1nn4qnk/f15_and_b17_overlay/

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SweetHomeNorthKorea@reddit

Holy hell just under 70ft long for B17. That’s almost a fifth of an American football field, or 0.179 the length of a European football pitch for you metric users out there

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Paxton-176@reddit

There is an interesting comment about the bombs dropped in Vietnam vs WW2 Europe.

US was sending fleets and fleets of bombers over Europe from Britain dropping bombs. These raids were planned days and weeks in advance. In Vietnam the US was sending A-6s that carried a payload bigger than WW2 bombers out hourly from South Vietnam and carriers with information being sent directly from basically everyone on the ground.

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aiij@reddit

Thanks! I actually have seen an F-117 in person too, but not since I was little. I don't remember it looking particularly big, but the same airshow also had a B-52 and a C-5.

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1II1I1I1I1I1I111I1I1@reddit

Yeah, definitely smaller than the big boys. For a clearer human comparison, here is an F-22 with the crew standing next to it

I know 3 guys who had to eject from an F-16 after engine failure. It happens more often than you might think, and the peacetime loss rate for F-16 is higher than the F-15

General Dynamics managed to convince the USAF that single engine aircraft were not much more survivable in combat than a twin, as any warhead taking out one engine would probably take out the other was well.

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FoxThreeForDaIe@reddit

It happens more often than you might think, and the peacetime loss rate for F-16 is higher than the F-15

Yep. AF Safety Center data shows that comparing F-15 to F-16, over their lifetimes (same eras, nearly identical motors), the F-15 engine-related Class A mishap rate is 0.26, versus 1.12 for the Viper

The Viper literally had FOUR times the engine-related mishap rate of the Eagle

General Dynamics managed to convince the USAF that single engine aircraft were not much more survivable in combat than a twin, as any warhead taking out one engine would probably take out the other was well.

Apparently Lockheed has continued that trend of spreading that idea, to the point where posters on here are literally repeating talking points that are fundamentally untrue

We literally parallelize critical systems - like servers and hard drive backups - because it increases reliability.

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mypoorlifechoices@reddit

How often do people shoot missiles at your servers? The argument you're making against the second point is just another argument in support of the first point. It's not an argument against "2 engines won't save you if you get hit by a missile."

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FoxThreeForDaIe@reddit

Looks like we have only had 1 engine failure in the history of the program so I would consider it pretty reliable at this point. Maybe to the point that it's not really a concern?

They didn't forget, but neither did the planners of Desert Storm. which is why the first 2-3 nights USAF F-117s thoroughly hammered Iraqi radar stations and command centers...

It's the only way to fully guarantee you have enough fuel for the rest of your flight.

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medney@reddit

But the short term savings are enormous

Potentially, but fitting it on an LHA/LHD parking spot and elevator - which was the other hard requirement - meant that it was impossible.

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BigJellyfish1906@reddit

No, it has one engine because of the F-35B. It’s really that simple.

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snow38385@reddit

The lead engineer from the program spoke at my airspace department in college. What he said was that the program was started to look at a way to replace the harrier with a more reliable VTOL aircraft. They wanted to use a fan in the front to provide lift because it solved a couple issues that the harrier had. The first being that exhaust was being sucked into the engine intake which reduced thrust close to the ground. The second was that lift being generated from the 2 thrust points colliding would counter act the ground effect. The engineering problem was engaging the fan without stalling the engine. They solved the engineering problem by diverting air around the engine to reduce the force on it while the fan was being spoiled up. All of this is to say that the aircraft was designed around a single engine with VTOL. The other branches got on board with variants for political/budget reasons. Maybe the justification was provided for single over dual based on costs, but the design had nothing to do with it.

_BrokenButterfly@reddit

Interesting, I didn't know that.

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Frederf220@reddit

The F-35 is STOVL but the other two F-35 aren't.

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Agloe_Dreams@reddit

Thrust vectoring is a very good point nobody else really made. A single engine with a standard outlet can do pitch and yaw thrust vectoring but not roll. Twin engines allow for pitch and roll, theoretically speaking, you could also pull back throttle on the left or right for yaw.

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The B variant was debated well after the original design decision to go single engine. Might recommend you read the spec differences for the C. Quite a bit bigger payload bays and fuel capacity.

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BlessShaiHulud@reddit

and early on, they also wanted to take possibility of the asymmetric thrust vectoring

pulse7@reddit

They're faster, so better defenders

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FZ_Milkshake@reddit

F-104 and F-106 disagree. Single engine aircraft have less drag, as long as there is enough thrust from that single engine, they can be just as fast, or faster.

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sound_scientist@reddit

Well it’s 2x louder innit?

Logical-Let-2386@reddit

People are giving the advantages of twin vs single engine. The disadvantage is cost of maintenance and sticker price. Believe it or not the JSF was envisioned as a (relatively) low cost do-everything airplane that could be bought in huge numbers.

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arvada14@reddit

Correct and down time. If one engine has an issue while on the ground its not like you're going to fly the plane half as fast. It's like a unicycle and a bicycle if one wheel gets a flat. Both vehicles are equally worthless and will both need the same amount of down time. So cost per time in the air is higher for twin engine fighters

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FoxThreeForDaIe@reddit

Correct and down time. If one engine has an issue while on the ground its not like you're going to fly the plane half as fast. It's like a unicycle and a bicycle if one wheel gets a flat. Both vehicles are equally worthless and will both need the same amount of down time. So cost per time in the air is higher for twin engine fighters

Except long-term down two engine jets can be cannibalized (i.e. parted out to other jets) to replace single engines in two other jets, whereas that single engine jet can only part out one other jet at most

In fact, the F-35 having awful availability rates has been in no small part due to major maintenance downtime in part because of its engines requiring maintenance at a higher rate than expected

You're also forgetting that in a single engine jet, the tolerances for when inspections and maintenance on that single engine jet is WAY lower than two engine jets. Predictive maintenance is critical in safely flying a single engine jet.

On the B, for instance, the lift fan is a flight safety critical item that requires its own shop of propulsion guys to manage. Not passing a vehicle BIT (which tests the lift fan) is a no fly.

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ServingTheMaster@reddit

max thrust for air superiority. its most efficient to have two smaller inlets and two motors. to get the same thrust out of a single engine the radius would need to increase 1.41 times. (since intake area is proportional to π*r\^2)

the overall volume of the engine increases much faster than the radius, since volume scales with r\^3. a larger engine would be significantly heavier and bulkier.

drag, structural constraints, etc. all indicate that two optimally sized engines will out perform a single engine.

The con of single engine is loss of redundancy. There are FAR more "Land as soon as possible" emergencies in the F-35 than twin-engine aircraft like the F/A-18. On land, that's not necessarily an issue. At sea, that can become a really big issue, bad, which is why the Navy has historically moved away from single-engine anything.

Same reason airliners aren't going single engine anytime soon.

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Basic-Reception-9974@reddit

Commercial passenger aircraft had a requirement for a minimum of 3 engines to cross the Atlantic or Pacific.

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FoxThreeForDaIe@reddit

Commercial passenger aircraft had a requirement for a minimum of 3 engines to cross the Atlantic or Pacific.

Yes, and now it's two. Point is, it's still not one, despite those engines being magnitudes more reliable than when we needed a minimum of three.

A single-engine jet still has significantly more single points of failure than a two-engine jet.

Hell, in the F-35, we have an entire backup system to generate electricity on top of already needing to essentially run two generators off our engine. It's extra weight we lug around when a two engine jet can get by with just a single generator running off each motor, because it would have been unacceptably low redundancy/reliability with just a single generator for our single motor

The Viper has similar issues, where you have the main generator, a backup generator, then an emergency generator.

So you ironically need more generators to achieve redundancy in a single engine fighter than the two generators - one per motor - that an Eagle, Hornet, or Raptor get by just fine with.

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Preindustrialcyborg@reddit

in a two engine plane, engine failure means you lose 50% thrust and will hobble to the airport

The f-35 is smaller and isn't expected to do the types of Maneuvers and acceleration the F-22 is expected to do.

Different aircraft roles require different engine configurations to make it work, even if they use the same engines

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aloopree@reddit

Two Fa35 engines? That's like double the stealth, zero extra fun.

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PcGoDz_v2@reddit

Thrust and trust.

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Free-Promotion886@reddit

Long range study on F16 and F15 showed no statistic advantage for the jet with two engines.

Those engines are highly reliable.

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FoxThreeForDaIe@reddit

Long range study on F16 and F15 showed no statistic advantage for the jet with two engines.

Those engines are highly reliable.

Want to share that study?

Because that's literally the opposite of the actual data

https://www.safety.af.mil/Portals/71/documents/Aviation/Engine%20Statistics/F-15%20ENGINE%20-%20RELATED%20CLASS%20A%20FLIGHT%20MISHAP%20RATES.pdf?ver=NFVV64LAZJk9bz1_Sqlm8w%3d%3d

https://www.safety.af.mil/Portals/71/documents/Aviation/Engine%20Statistics/F-16%20ENGINE%20-%20RELATED%20CLASS%20A%20FLIGHT%20MISHAP%20RATES.pdf?ver=c5-t1D6mi-cVNceCqyQEAg%3d%3d

Same era, largely same engines:

F-15: total 13,646,734 engine flight hours, 35 Class A's, 0.26 engine-related mishap rate

F-16: total 11,365,923 engine flight hours, 127 Class A's, 1.12 engine-related mishap rate

The single engine fighter had a FOUR TIME greater engine-related Class A mishap rate

I genuinely don't know where this "single engine is more reliables/after than two-engine" BS started online, but this goes against basic industrial and systems engineering and math

There's a bunch of tradeoffs. Bigger engines tend to be more efficient for the power output, but if something goes wrong, or someone shoots your combat plane, then that was the only engine keeping you in the air.

There are also changes in how the plane flies, trust can be vectored or varied between the two engines, etc.

Two engine planes have wider bodies and more internal space to add capabilities. They tend to be longer range and more heavily armed.

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No_Mathematician_599@reddit

Yes there are many advantages.

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Robert-Berman@reddit

I am getting ready to retire from the Air Force and I’ve spent 13 years maintaining the F-22 and the capability is something that I feel is unrivaled. But, I think the thing most people don’t realize is the cost per flying hour. On the F-22 it costs around $53K per hour flying and most local sorties can be between 1 to 2 hours and sometimes they might fly a 12 turn 8. This is not the highest costing aircraft. I could talk about this aircraft for days and nights.

Some steering with a hydraulic failure

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No-Level5745@reddit

Reliability is a bit of a myth. The Navy had many successful single engine airplanes (A-4, A-7, F-8 just to name a few). The issue is more nuanced. Two engines are just that many parts that can fail...so an airplane with two engines is twice as likely to lose ONE engine than the single engined version, but the odds of losing BOTH engines is far less.than the single engined version

Warning...Math ahead: If the odds of losing an engine is 1% (really less than that but the math is easier), then the odds of losing 1 of 2 engines is 2x1% or 2%. However, the odds of losing BOTH engines is 1% squared (0.01*0.01 =0.0001 or .01%).

Two smaller engines means each engine has less inertia. You can get a faster throttle response from two smaller engines.

A single larger engine tends to be more efficient than two smaller engine, plus tends to be a bit easier on maintenance and reliability.

But if you lose an engine in a single engine fighter…

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BeancanGrenade@reddit

Man im on my phone half asleep thinking the upper image is an ottoman cannon the whole time

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danmarce@reddit

Jesús, guys, you all are Nerds.

Having witness both of these styles of aircraft perform. I can attest that both have certain roles , hence design choice.

BowtieSyndicate@reddit

How are you taking photos in these facilities aren’t they DOD?

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Known-nwonK@reddit

One is none and two is one

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Hank_moody71@reddit

2x the thrust…. Plus the safety of 2

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Hot_Pea9820@reddit

Redundancy and thrust vectoring.

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gramoun-kal@reddit

Planes that have one engine are made that way to keep things cheap.

Planes that have two engines are made that way so that the plane can come home after an engine failure.

This is particularly important for planes that operate a lot over the sea or over enemy territory.

So, while it's ok to have only one engine on short range defensive fighters, naval or long range strike fighter, or air dominance escort fighters are usually designed with two.

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gehacktes@reddit

The advantages to disadvantages are exactly what you think about

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LycraJafa@reddit

F35's single engine contributes to its low cost.

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AmmoTramp@reddit

Range, g loading, turn rate, larger avionics package(W Weasel), acceleration, single solution vs “double trouble”.

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Redundancy. Higher chance to survive combat missions.

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tasteslikechicken67@reddit

If you lose one, you still have one.

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Martha_Fockers@reddit

One engine big

Two engines smaller

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HyoukaYukikaze@reddit

Sometimes there simply is no single engine that can provide required thrust.

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laser14344@reddit

POOOOOOWWWEEEEEEERRRRRR!

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clownpirate@reddit

FWIW the Chinese J-35 seems to at least look like what a two engined F-35 would be. And without the complexity of the B variant getting in the way.

Who knows how it actually performs, and what its avionics are like, but it certainly looks the part.

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Old_Sparkey@reddit

Single engine designs are usually cheaper to maintain and less complex in design while multi engine designs are more reliable (duplicated systems) and have more power available. Single engine designs also tend to be smaller than multi engine designs. Both designs have their place.

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InigoMontoya1985@reddit

Q: Why are two engines in an airplane better than one?

A: The second engine will carry you to the site of the crash.

(A&P humor)

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BeatMastaD@reddit

Everything in tactical aircraft is tradeoffs. It becomes more obvious with an extreme example: why is a commercial 747 designed differently than the F-22? The answer is that they were made to do different tasks. The F-22 is much better at maneuvering, engaging enemy aircraft, but it utterly fails at the task of transporting 100 people from one place to another. The F22 and F35 have different designs for the same reasons, but their mission requirements are more similar, so they are more similar to eachother than to a 747.

Two engines gives you redundancy, better thrust control and vectoring, but in exchange youve gotta make space for two engines, fuel consumption is probably higher, maintenance cost, etc.

The F-22 and F-35 engines are also very different engines so its not just "two vs one". F-22 is designed to fight other planes and be able to out-maneuver them. F-35 is designed to detect, identify, and guide long range missiles to enemy targets. It doesnt have to be as maneuverable as the F-22 because its not supposed to be that close to enemy aircraft.

The argument over twin vs single engine in a fighter plane is the modern version of the 19th century argument betwixt straight and curved cavalry sabres:

A single engine is more efficient than 2 engines: although thrust produced per pound of engine weight is roughly equivalent, 2 engines require more structural weight than a single engine. Two engines also cost more if not in acquisition cost, then in O&M as they require 2 times as many parts, etc.

If there’s a single engine in the thrust class available, it would be more efficient and is often chosen, unless the mission requires the additional safety of two engines.

The F-22 has 2 engines because of the relatively high weight combined with the high performance requirements dictating high thrust. Additionally, 2 engines provide a simpler thrust vectoring scheme providing roll authority by putting the nozzles in different angles.

There’s also the requirement for an internal weapons bay, which for the F-22 is on the centerline of the aircraft. Intake ducts route air outboard of the bay: it would require a longer, heavier airframe to turn the air into a single engine.

The F-35 solution was to have the weapon bays on the side and route air inboard of the bays to a single engine. Boeing tried that on the X-32 but chose a single larger inlet. Both designs bent the ducts to hide the compressor face for RCS reasons. Lockheed curved the ducts from the side to the middle, but with a single intake Boeing had to curve the duct vertical which accounts in part for the X-32’s appearance.

For decades the USN required 2 engines because they operated far from shore, making search and recovery operations very difficult. This finally changed with the F-35, the first single engine fighter in USN service since the introduction of the A-7 in the 1960’s.

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Fit-Bedroom6590@reddit

Flying on no engine is way more exciting then flying on one remaining. Perhaps that is why they installed ejections seats.

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garmack12@reddit

In very general terms the Navy prefers twin engines and the Air Force likes single. Single engines are cheaper to operate but twins are more likely to make it back to the boat.

Op post on two subs because the plane subreddit is usually nicer than the aviation subreddit. The aviation will downvote all the questions while the plane has funny jokes that I love. So it balances out, if I wanted to farm I'd just post on planes

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ChiehDragon@reddit

Pros of 2 engines

redundancy
more flexible airframe shape
more afterburner thrust

Cons of 2 engines - Maintenence costs - lower efficiency - more weight

2 engines good for powerful, sleek top-end aircraft that carry a lot and need to go fast or perform in high-risk environments or over long distances.

1 engine good for light aircraft that are deployed in large numbers and primarily operate within a few hours of their base.

22 is designed to be a special super-solider to dominate multiple threats in any environment. The 35 is designed to be the backbone air infantry deployed from carriers and forward bases that works in tandem with other units to complete the mission.

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Derfflingerr@reddit

whats the advantage of 2 horse instead of 1 horse in a carriage?

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Direct_Program2982@reddit

Comment section straight out of r/shittyaskflying

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Speckwolf@reddit

Yes, you have twice as many engines this way.

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Final-Muscle-7196@reddit

Why not just strap a couple middle launchers on the falcon starship.

Geez a lot of random thoughts put together suggesting some rational resulted in two engines or one.

If you worked in complex engineering programs sometimes how decisions are made is not completely logical.

Redundency, easier to fit 2 smaller engines into a rectangular shape if that's what you desire

It's all a trade ofd depending on what your goals are.

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koolerb@reddit

Twice as much to go wrong.

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raidriar889@reddit

Two engines are more powerful than one and if one engine fails you still have the other. But two engines are more expensive, and they require more maintenance.

The F-22 and F-35 were designed to meet different requirements. The F-35 is smaller and lighter, and meant to be procured in very larger numbers and having only one engine contributes to its cost being roughly a quarter of the F-22. The F-22 was designed to be fast and powerful, not cheap.

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deadgirlrevvy@reddit

Yes. There are two major advantages:

Redundancy. If one engine malfunctions or is disabled by enemy fire, the plane can still fly home.
Power. Two smaller engines can develop more power than a single large engine while taking up less concentrated space. This means that instead of taking up the entire fuselage with one giant engine, you can restrict the space useage to the rear half of the aircraft. Doing this is useful for many reasons, the primary being that it allows a lot more flexibility in aircraft design.

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