Why Can’t ANYTHING Replace THIS Aircraft?

0:01 Can one aircraft do basically everything?

0:05 Well, the C-130 Hercules, or the Herc as it's known to its friends,

0:10 is primarily a military cargo aircraft.

0:13 But it has also been used to carry paratroopers,

0:16 it can land on dirt, ice or snow, it has snooped on people,

0:21 it can refuel other planes and helicopters, fight fires and spray crops,

0:26 chase hurricanes and has performed all kinds

0:28 of humanitarian and research work known to man.

0:33 It has also landed on an aircraft carrier, it has dropped bombs,

0:37 big and small, and it's even managed

0:39 to recover spy satellites returning from space.

0:43 So how has one aircraft been able to do

0:46 all of those things and kept going for so long?

0:51 Because if you thought that the Boeing 737 has

0:53 been in production for longer than any other aircraft,

0:56 then you're actually wrong.

0:59 The C-130 entered service 12 years before the first 737

1:03 and has now been produced continuously for over 71 years.

1:08 Nothing even comes close to that.

1:12 In this video, we are going to look

1:13 at how the C-130 became such a lasting success,

1:17 which is made even more incredible considering that it almost didn't happen.

1:22 You see, Lockheed's most celebrated aircraft engineer absolutely hated it.

1:28 And finally, we're also going to look at if

1:30 there is anything out there that could eventually replace it.

1:35 Now, I will start this story by looking at a recent

1:39 incident involving a C-130 that got a bit hairy and expensive,

1:43 but serves as a great example of just how durable this aircraft is.

1:49 On the 23rd of April in 2020, a US Air Force C-130J-30 was on approach

1:55 to Runway 26 in Rammstein Air Force Base in Germany.

2:00 Now, the weather was fine,

2:01 although using that particular runway meant a six-knot tailwind,

2:05 which was by design.

2:08 You see, the pilot sitting in the left seat on that day was being evaluated,

2:12 and that check-ride involves a number of different tasks,

2:17 including flying formation with two other C-130s,

2:20 and also something known as a maximum effort landing.

2:25 A maximum effort, or assault landing,

2:27 is a tactical landing flown at slower speeds to enable

2:30 the plane to stop in as short of a distance as possible.

2:34 Now, there were quite a few complications in this approach,

2:37 including that tailwind, and to put it mildly, it didn't go as planned.

2:43 According to the accident report, the pilots started pulling back on the thrust

2:47 levers a bit too early during the flare, at around 70 feet above the runway,

2:51 bringing them back to the flight idle at around 45 feet.

2:55 In normal conditions,

2:56 that thrust reduction should have started at around 20 feet,

2:59 so this was very early.

3:02 Now, doing this is particularly bad in the C-130,

3:05 because the prop wash is actually helping

3:07 the wing generate lift during low speeds,

3:10 enabling it to land as slowly as possible.

3:13 Now, this didn't stall the plane, but it did cause a high sink rate,

3:17 which both pilots were then too late to react to.

3:20 The pilot sitting on the right seat called for a go-round

3:24 when the aircraft was about 30 feet above the runway,

3:26 and the pilot flying had, at that point,

3:28 already started doing that by pushing the thrust

3:31 levers forward and starting to pitch up.

3:34 But like I said, it was still a bit late,

3:37 and with the engines already at idle at that point,

3:40 they now couldn't spool up fast enough

3:42 to stop the plane from touching down hard.

3:46 Now, a maximum effort landing is a fairly hard landing anyway,

3:49 but every aircraft has a certain limit

3:51 for this, and the C-130 is no exception from that.

3:55 The maximum descent rate at touchdown that this plane should have had was,

4:00 based on its weight that day,

4:01 about 540 feet per minute, and the maximum load with the flaps extended was 2Gs,

4:08 or twice the force of gravity.

4:11 In this case though,

4:12 the plane touched down with a descent rate of approximately 834 feet per minute,

4:16 giving it a peak instantaneous g-load of between 3.62 and 3.81 Gs.

4:23 Now, despite this, the aircraft still went

4:25 around before the nose wheel touched the ground,

4:28 and initially the crew briefed for another

4:31 maximum effort landing in the opposite direction.

4:35 But as they prepared for that, the pilots noticed the max G-load

4:38 of 3.7 and 3.8 Gs from their previous landing in their primary flight displays,

4:43 which obviously made them change their plans.

4:46 So instead, they now made a more docile, uneventful landing with full flaps,

4:51 followed by a taxi into the parking area and them shutting down the engines.

4:56 And had this not been a C-130 Hercules,

5:00 that would likely have been the very last

5:03 flight that this plane would ever have done.

5:06 Because you see, the damage turned out to be pretty brutal.

5:10 There was buckling in the skin on the underside of the airframe,

5:13 and even worse than that, there were popped rivets and cracks all over the wing.

5:18 In the weeks after the incident,

5:19 maintenance crews at Lockheed Martin determined that the list

5:23 of damaged parts included the main landing gear,

5:26 propellers, propeller gearboxes,

5:28 spinners and other related parts on all four engines,

5:31 as well as all wing sections.

5:34 Now on most aircraft, such an extensive shopping list of broken parts

5:38 and components would simply be uneconomical to repair or replace,

5:43 if it even would be possible.

5:44 And yet, here is a photo of this same aircraft flying five years later.

5:51 Now to understand how this was even possible,

5:53 we need to look at the design of the C-130 a bit more closely.

5:58 And here, we should also address a small misunderstanding about this aircraft.

6:03 Kelly Johnson is one of the most

6:05 prolific aircraft designers in the 20th century.

6:08 Working for Lockheed, he designed many famous planes,

6:11 starting with the Model 10 Electra,

6:13 which was the plane that Amelia Earhart disappeared in.

6:17 He also designed the P-38 fighter, the Constellation,

6:20 the P-80, the T-33, the U-2 Spy Plane,

6:24 the SR-71 and its many, many derivatives, as well as the F-104, among others.

6:32 Quite a busy guy, in other words.

6:34 But unlike what some sources suggest, Johnson did not design the C-130.

6:40 And not only that, when he first took a look

6:42 at the written specifications and at an early model of the plane,

6:46 he turned to Lockheed's vice president

6:48 and chief engineer at the time, Hall Hibbard,

6:51 who had just gotten ready to send those specifications to the Air Force.

6:56 And Johnson said, "Hibbard, if you sign that letter,

6:59 you will destroy the Lockheed company." Now,

7:03 Willis Hawkins, the engineer who led the design team behind the C-130,

7:07 later explained this, saying that while Johnson was a genius,

7:11 he wasn't impressed by a simple transport plane that didn't carry bombs,

7:16 didn't have machine guns and didn't fly at Mach 3.

7:20 Also, every single plane Johnson designed looked sleek and fast,

7:24 even when it was sitting still on the apron.

7:27 And with all of the will in the world,

7:30 you just can't say that about the Hercules.

7:33 Now, Johnson eventually changed his mind about this plane,

7:36 and there is a really simple and practical reason

7:40 why the C-130 looks the way that it does.

7:43 World War II and the Korean War that followed both showed the military

7:47 that they really needed a medium-sized transport

7:49 aircraft that could land on unprepared runways.

7:53 Smaller aircraft with radial piston engines like the Douglas DC-3 or C-47

7:58 in military service could already do

8:00 that, but the Air Force needed something bigger,

8:03 with a ramp that would allow loading

8:05 and unloading of cargo to be done much faster.

8:08 Now, the C-130 wasn't the first plane to be

8:11 able to land on bad terrain or have a ramp.

8:14 Actually, it borrowed quite a lot of its

8:16 features from an older design called the Fairchild C-123,

8:20 which was quite successful in its own right,

8:24 even though its design had actually started out as a glider.

8:28 But the C-123 wasn't big enough to carry what the Air Force needed,

8:32 and like every other transport plane at the time,

8:35 it had piston engines, not turboprops.

8:39 Thus, the Air Force drafted a requirement for a new, bigger transport aircraft,

8:44 and the nature of this requirement meant that this new

8:47 plane would literally have to be designed from the inside out.

8:51 And crucially, the feature that would lead

8:53 to the C-130's longevity came almost as an afterthought,

8:58 which is quite astonishing as we will soon see.

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10:54 Now let's get back to the Herc.

10:57 In its descriptions of the new transport plane that they wanted,

11:01 the US Air Force didn't specify the dimensions of the aircraft itself.

11:05 Instead, they provided a list of payloads involving vehicles and other pieces

11:10 of equipment that the aircraft would need to be able to carry.

11:14 Willis Hawkins, the plane's chief designer,

11:16 explains what his team did in response.

11:20 We basically took the dimensions of the biggest

11:23 piece of equipment the Air Force had specified,

11:25 drew a circle around its cross-section,

11:27 and then turned the circle into a tube about the length of a railroad boxcar.

11:33 We then put wings, a nose and a tail on it, and we had the design.

11:38 It was basically that simple.

11:40 Okay, there was a little bit more to it than that.

11:43 The plane also needed very sturdy but low landing gears,

11:46 so the ramp in the back wouldn't need to be so steep,

11:49 and it was configured so that it

11:52 wouldn't need any ground equipment to stay operational,

11:54 basically as long as it had fuel in its tanks, it would start up and fly.

12:00 The design then also had to be optimized for low speed,

12:03 so at least when it entered service,

12:05 its engines and propellers were set up to prioritize

12:08 maximum thrust at low speeds instead of efficiency in cruise.

12:13 Basically, the opposite of how airliners are designed, sort of.

12:18 But fundamentally, the C-130 was designed as a container with wings,

12:22 with the room and the necessary weight capacity to handle quite

12:25 a lot of equipment that the military was already familiar with.

12:29 And that was the reason why this aircraft eventually became so successful,

12:33 but more importantly, its size quickly became sort of a standard.

12:39 After the C-130 had entered service,

12:41 the US Army, and other armies for that matter,

12:44 would issue requests for new equipment that would

12:47 need to be air-transportable in a C-130.

12:51 And that led to the designs of some quite popular military vehicles,

12:55 like the M113 Armoured Personnel Carrier for example.

12:59 This standardization is a key reason why the C-130 was

13:03 able to stay in demand for such a long time.

13:06 It became the literal standard,

13:09 similar to the containers that we see on roads and cargo ships today.

13:14 Designers of a lot of newer military equipment then soon assumed

13:17 that their products would have to fit into the C-130 as well,

13:21 even if the specifications didn't say so.

13:24 Palletized equipment was then developed to fit the aircraft

13:28 to cover everything from military to civilian research projects.

13:32 Basically anything that involved getting to hard-to-reach places with no

13:36 runways would ease the fitting of bulky firefighting equipment.

13:41 There is also a commercial version of the C-130,

13:44 called the Lockheed L-100-Hercules,

13:46 which has been made in a few different versions,

13:49 although that hasn't been in continuous

13:51 production like its military equivalent have.

13:54 This feedback loop of specifications made

13:57 the Hercules a kind of a do-anything aircraft.

14:01 The US Air Force did try to replace it a few times.

14:05 A project called the Advanced Medium STOL Transport, or AMST for example,

14:10 was intended to replace the C-130 in the 1970s and 80s,

14:14 but like other prospective replacements,

14:17 it soon proved too costly or too complex for little extra benefit.

14:22 Here it is worth adding that unlike the airline world,

14:26 in the military efficiency isn't everything.

14:29 The Hercules is overbuilt anyway with its nice, thick,

14:33 low aspect ratio wing that is designed

14:35 to maximize lift at low and medium speeds,

14:38 so more modern designs, who promised to be more efficient and faster,

14:43 might not seem as attractive as their designers assumed that they would do.

14:48 Instead what ended up happening was that various

14:50 other designs were created who would end up

14:53 supplementing the Hercules in Air Force services around

14:56 the world by being either bigger or smaller.

14:59 But there still is one more element in this story,

15:02 which takes us back to that C-130 that made that heavy landing in Germany.

15:07 How was it possible to even repair that aircraft?

15:11 Now remember how the C-130's original designer described it?

15:15 A container or box car with wings,

15:17 nose and a tail that can land in a battle zone?

15:21 Well, the area that we need to concentrate on here

15:24 is the point where the wings meet the fuselage.

15:27 This is called the center wing box,

15:29 and all big aircraft have a structure similar to it.

15:33 In low wing aircraft like the C-737 that I fly,

15:36 the wing box is where all of the loads from the wing

15:39 and the landing gear meet the rest of the aircraft.

15:42 High wing aircraft are a little bit more complicated because

15:45 the landing gear isn't attached directly to the wing box,

15:48 which means that the fuselage section between the wings and the gear

15:52 has to be sturdy enough to still be able to transfer those loads.

15:56 And that is actually why high wing designs generally tend

15:59 to be a bit heavier than similar low wing designs.

16:03 But either way, in most cases a center wing

16:06 box is not a replaceable part in an aircraft.

16:10 Even if such a replacement would be possible theoretically,

16:13 you would essentially need to disassemble the whole aircraft to get to it,

16:18 in most aircraft, but not the C-130.

16:22 Now in the Hercules, this center wing box includes a section of the wing

16:26 up to and including the mounts for the two inboard engines,

16:29 which is mounted above the cabin.

16:32 And crucially, the way that it is mounted there means that it can be replaced,

16:35 which is a big deal.

16:38 You see, the lifespan of most complex modern aircraft is limited by fatigue,

16:43 and that fatigue can affect many areas,

16:46 but usually the ones that limit an aircraft's lifespan involve either

16:50 the compression and decompression cycles or wear on the wing and wing box.

16:56 When an aircraft completes a specific number of flight cycles,

16:59 flight hours or a combination of both,

17:01 well then it's just retired and broken up.

17:05 But in a beefy aircraft design like the Hercules,

17:08 which doesn't cruise quite as high as most airliners do,

17:11 it's the wing and wing box that would limit the plane's life,

17:16 if it hadn't been replaceable.

17:18 In the C-130, the center wing box is something called a lifed article.

17:23 Those are critical components or systems that have operational

17:26 limits specified in total flight hours, age or both.

17:30 In the case of the center wing box of the Hercules,

17:33 most of the early variants of the plane

17:35 had limits of around 19,000 flight hours,

17:38 although that number depends on the type of flying that that aircraft

17:41 had been subjected to, and calculating this number properly is really critical.

17:48 Back in 2002, a very early C-130 Alpha model, used for firefighting,

17:53 crashed very dramatically and killed all three crew members on board when

17:57 the wing box failed and the two wings folded upwards one after the other.

18:02 Those earlier wings were weaker, and at the time of the accident,

18:05 there were some serious maintenance

18:06 and operation-related issues with this specific aircraft.

18:10 But another important factor was that aircraft used in firefighting roles

18:14 are subjected to much higher stresses than planes just flying normal cargo,

18:19 something that hadn't been taken into account

18:21 in the maintenance and inspection schedules of that aircraft.

18:26 Now, in the newer C-130J,

18:29 the original center wing boxes had a limit of 45,000 flying hours,

18:33 up from 19,000 before, but more recently Lockheed has introduced

18:38 an enhanced service life, or ESL center wing,

18:41 initially estimated to be good for 90,000 hours, which is just crazy.

18:46 And Lockheed now even says that the ESL

18:49 wing actually has a proven lifespan of 122,500 hours.

18:54 In any case, like with other lifed parts,

18:57 once these center wing boxes are replaced, the life clock is reset on it,

19:01 and the hours of flight cycles start counting up from zero again.

19:05 And that matters, because getting used in unusual roles,

19:08 like firefighting or chasing hurricanes, would otherwise have quickly eaten up

19:12 the available flight hours of many middle-aged C-130s.

19:16 If it hadn't been possible to give them that new

19:19 leaf of life with a new wing box, that is.

19:22 Now, to be clear here,

19:23 replacing the wing box on a C-130 isn't an easy or cheap operation.

19:28 But if the rest of the aircraft doesn't have any other fatigue-related issues,

19:32 or isn't so old that its systems and other components are too hard to maintain,

19:37 well then it is a job worth doing.

19:39 The total cost of a C-130 wing box replacement is a little bit hard to find,

19:43 and will also vary depending on where it's being done and by whom.

19:48 But in 2007, the US Air Force priced the operation at $6.5 to $7 million,

19:54 which is still only a small fraction of the cost of getting a new C-130.

19:59 So if we go back to that C-130 that landed hard in Rammstein,

20:02 Germany, this was an aircraft built in 2013, so it was relatively new.

20:07 And even though that accident also required much more repairs and parts,

20:11 including four rebuilt engines,

20:13 the total cost of that operation was around $20.9 million.

20:19 Not cheap, but a brand new C-130J-30 would cost several times that amount,

20:25 so now maybe you start to understand why this was done and how it was possible.

20:31 But there was also an additional twist to that story.

20:34 You see, there is one company that can perform such a wing

20:37 replacement outside of the United States

20:39 called the Marshall Group in Cambridge, UK.

20:42 But the US Air Force themselves had only

20:44 ever done this job inside of the United States.

20:48 So for them to perform this field wing replacement in Germany,

20:51 the Air Force first had to figure out how to pack up and ship a wing over there,

20:56 and the job then also required quite a bit of precision,

21:00 special gigs and other mechanisms.

21:03 So all in all, pulling off this repair

21:05 and all the other repairs that this Hercules needed,

21:08 including the time needed to build the new wing and ship it across the pond,

21:12 took over five years.

21:15 Now one question that we haven't been able to find out, none of us in the team,

21:19 is whether or not the US Air Force actually intended

21:22 for the wingbox to be replaceable back when it was designed,

21:26 or if this was just a lucky coincidence in the way that the C-130 was built.

21:30 And if you guys know anything about

21:33 this, please let us know in the comments below.

21:36 Finally, there is also one more question that needs to be answered.

21:40 Is there any other aircraft out there that could

21:42 possibly replace the C-130 in the near future?

21:45 Well, Airbus tried it with their A400M, which actually did win some orders,

21:51 but not enough to really replace the C-130.

21:54 Well, in most countries at least.

21:55 But another possible candidate is the Embraer C-390.

22:00 This aircraft has a similar size and capacity as the C-130J-30,

22:03 and instead of four turboprops, it has two IAE V2500 turbo fans.

22:10 Those are the same engines used on many legacy Airbus A320s.

22:14 Sales for this aircraft suffered badly at first,

22:17 very likely because of the failed tie-up

22:19 between Boeing and Embraer back in 2020.

22:22 But in the last couple of years,

22:23 Embraer has secured a lot more orders for the plane,

22:26 so it is definitely one to look out for.

22:30 As for the C-130, well, it's still in production, so don't dismiss it just yet.

22:36 And even when no new ones are made anymore,

22:39 the existing models will take a very long time to go out of style.

22:44 As we saw in another video we did recently,

22:47 Boeing's B-52s will very likely stay in service for over a century.

22:52 But the B-52 was actually in production for only around a decade,

22:56 and when the last one of them is retired,

22:58 there will likely be a lot of C-130s still flying around,

23:02 proving that you don't have to be fast or good-looking to be cool.

23:07 So what do you think?

23:08 What is your favorite strange role that the C-130 has performed?

23:12 Let us know in the comments below.

23:14 Thank you all for watching,

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23:32 My name is Petter Hörnfeldt, and you're watching Mentour Now!

23:35 Have an absolutely fantastic day, and I'll see you next time.

23:38 Bye-bye.