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Design and Development of the F-35 Lightning II

Tylin Waters

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Abstract

This document is intended to help engineering students and new engineers,

particularly electrical, mechanical, software, and aerospace engineers by illustrating the

external factors such as budget changes, politics (both internal and external), changing

design specification, and deadlines that engineers will face when working on large

projects, especially those with government funding. It will cover a brief history of the F-

35 Lightning II Joint Strike Fighter Program, the technical specifications of the plane, the

controversy that has surrounded the project, and the expectation place on engineers in

such positions.

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Introduction

The F-35 Lightning II fighter jet, named after the legendary WWII fighter, the P-38

Lightning, has had one of the most turbulent and controversial design and development

phases of any government funded engineering projects ever attempted. It has gone

over budget on several occasions, undergone complete refits and redesigns, and has

been panned by some as being inferior to the very jets it is meant to replace. It has

been in development for decades but has only recently come into active service for the

military.

Figure 1 - F-35B variant

https://www.flickr.com/photos/lockheedmartin/38218765112/in/album-

72157601438420763/

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A Brief History of the F-35

The F-35 Lightning II is the fighter jet developed by Lockheed Martin. It is

classified as a 5th generation fighter which means it is capable of “advanced stealth,

extreme performance, information fusion, and advanced sustainment.” While in previous

generations of aircraft, stealth capabilities were limited to bombers and attack planes

like the B-2 Spirit or F-117 Nighthawk, 5th generation planes like the F-35 and F-22

Raptor combine advanced stealth with the ability to engage in air-to-air combat. It has

been one of the most ambitious military projects even undertaken and represents a

technological quantum leap over its predecessors.

In previous generations of fighter aircraft, dating all the way back to World War I,

different types of planes were built specially for each branch of the military. The Navy,

for example, has utilized the F-14 Tomcat and F/A-18 Hornet which are specifically

designed to land on aircraft carriers. They achieve takeoff via a literal catapult mounted

to the runway that rapidly accelerates the plane and launches it into the air. In order to

land, jets approach the carrier with a hook hanging off the back of the fuselage and use

it to snag one of a series of cables laid across the runway which arrests the plane’s

forward inertia, allowing it to make a quicker stop. Other specialized planes, such as the

British made AV-8A Harrier Jump Jets, are capable of vertical/short landing and takeoff

(V/STOL) via rotatable jet nozzles.

The F-35 is the first of its kind in that it was designed to replace current

generations of fighter and attack planes across all branches of the military. It is the

result of Department of Defense (DOD) Joint Strike Fighter program which was

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introduced in late 1980s. Proposed aircraft designs were submitted by several

contractors including Lockheed Martin, Northrop Grumman, Boeing, and McDonnell

Douglas. From those original proposals, Boeing and Lockheed Martin were selected to

build prototypes for the program. Boeing’s design, dubbed the X-32, and Lockheed

Martin’s prototype, the X-35 were tested and compared for over a year from 2000 to

2001. In October of 2001 it was announced that Lockheed Martin would develop the

Joint Strike Fighter, now christened the F-35, in conjunction with Northrop Grumman

and BAE, a British based aerospace contractor (1). The F-35As are designed for

conventional takeoff and landing (CTOL) and are set to replace the F-16 Fighting

Falcons and A-10 Thunderbolt IIs for the Air Force. The F-35Bs are capable of short

takeoff and vertical landing (STOVL) and will replace current Marine Corps F/A-18

Hornets and AV-8B Harriers. Finally, the F-35Cs are made for catapult-assisted takeoff

but arrested recovery (CATOBAR) for aircraft carriers and will replace the current Naval

fleet of F/A-18s (2).

The F-35 program is an international project and has received support and

funding from several countries and be replacing planes and components from those

countries as well. There are nine partnering countries in total, Australia, Canada,

Denmark, Italy, the Netherlands, Norway, Turkey, the United Kingdom, and the United

States. In addition to these partners, several countries are purchasing F-35 for their own

militaries as foreign military sales customers including Israel, Japan, the Republic of

Korea, Belgium, and Finland (2).

Specification

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The if F-35 is one of the most ambitious engineering projects undertaken by a

government contract. Aside from the three variants for the different branches of the

military, the F-35 represents a quantum leap over previous generations of fighters.

While the United States’ other 5th generation fighter, the F-22 Raptor, is an

improvement over 4th generation fighters like the F-15 Eagle, F-16, and F/A-18 while

incorporating advanced stealth capabilities, the F-35 represents a complete revamping

of the way modern fighter planes are designed to engage in combat (2).

One of the key features of the F-35 is the visor system. Most pilots receive

tactical information from their heads-up display (HUD), a glass display mounted inside

the cockpit. The HUD provides information on altitude, airspeed, weapon/combat

systems, GPS, and friend-or-foe trackers. The F-35 however has no HUD; instead it

uses what is called a Helmet-Mounted Display System (HMDS). On these highly

advance helmet systems is mounted a bubbled visor that project all this data right in

front of the eyes of the pilot which means he/she does not have to look at a singular

spot in the cockpit to receive the relevant information.

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Figure 2 - F-35 Gen III Helmet-Mounted Display System (HMDS) -

https://cdn.aviationtoday.com/wp-content/uploads/2018/08/f-35ed.jpg

The primary feature of the HMDS however is not just making HUD information

more accessible, but in giving the pilot 360-degree visual data. The visor is linked to a

real-time feed from several cameras mounted across the body of the jet, allowing pilots

to “look straight through the plane” and see locations of friendly and enemy forces. This

also means pilots are no longer required to point the nose of the jet at an enemy to

achieve missile lock, they can now simply look at the target to receive lock and fire. The

HDMS fetches a $400,000 price tag and are 3D molded to each individual pilot (3).

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Figure 3 - Visual from HMDS -

https://cdn.aviationtoday.com/wp-content/uploads/2018/08/f35greened.jpg

What truly sets the F-35 apart from other fighters is not the helmet system or the

different variations but is mobile sensor package. All of the F-35’s sensor systems are

designed to share and receive combat data to and from other aircraft as well as ground-

based sensors; it also combines all of the information from each of its sensory suites

including infrared, radar, electronic warfare systems, and Doppler radar. With previous

fighter jets, pilots required constant communication with other pilots and ground-based

communications to verify locations of targets, objectives, and friendly forces. They were

also required to sift through and interpret all this information on the fly (literally) while

flying at the speed of sound. The sensory suite for the F-35 on the other hand collates

and interprets all this information on its own and projects the results to the visor. If the

information is regarding unknown forces, it will also project how confident it is in the

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inspiration while continuously cross referencing the results with other sensory stations in

order to increase accuracy (4).

Controversies in Development

The development of the Lightning II has been fraught with controversy ranging

from budget, time of delivery, performance, and specifications. It has been delayed

several times and continued to face speed bumps during its design phase.

One major theme across the development of the F-35 has been the budget,

specifically the fact that it has gone over the originally proposed budget several times

throughout the development phase. The original budget was set at around $200 billion

for 2,457 planes but that figure it now at about $400 billion (7). This is due in large part

to the F-35 being such a quantum leap over any jet built up to this point in terms of

overall technology and capabilities in terms of flight avionics, stealth flight, and payload.

Figure 4 – Cost of fighter jet models (in millions)

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Regarding Fig. 1, while the F-22 costs more than the F-35 per unit, there are

significantly more F-35s proposed as they are meant to replace the bulk of the Air

Force, Marines, and Navy’s current fighters (8).

There have also been questions as to whether the F-35 is even better than the

planes it was designed to replace. In early test dogfights, the F-35 was considered by

many to be inferior to the F-16 (although this can possibly be attributed to the notion

that the pilots were flying the F-35s the same way they would fly an F-16 which is not

how they were designed to fight).

Every single current generation (also known as 4th generation) fighter, including

the F-16, F/A-18, and even the renowned F-15, were originally introduced in the 1970’s

when air-to-air combat was still fought with traditional dogfighting tactics. The F-35 was

not designed to engage in close quarter dogfights, but rather to detect enemy targets

and fire at them from several miles away. During initial test combat scenarios in 2015,

the F-35 reportedly lost to the older F-16 and F-15 fighters. For many, this was proof

that the F-35 was inferior and that the US government was spending an inordinate

amount of money for a less effective fighter design. While there were certainly design

flaws regarding manual control of the aircraft and lessened maneuverability and thrust

that would need to be addresses, the issue wasn’t so much with the flaws of the fighter

itself, but rather pilots trying to fly it like an older generation jet. In a more recent training

exercise in which the test pilots have had considerably more time to familiarize

themselves with the niches of the system, the F-35 recorded a 20:1 kill ratio against the

4th generation fighters (5).

Effect on Designers and Engineers

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Logistics

Because of the fluid nature of the project, engineers have been continually asked

to change their designs to meet an altered need or to fix existing problems. The other

(and most significant) challenge facing the engineers was that many of the features

proposed in the design for the F-35 were brand new and had never been attempted

before.

The constant delays and budget increases and cuts in a project like this may also

lead to a great deal of stress, particularly when engineers must remain committed to

such a large project far longer than they were initially counting on. Although in the case

of the F-35, the budget has increased over time, many departments have had their own

budgets cut and are expected to make the same level of progress with fewer resources.

Automation

Because of the highly automated nature of the F-35, engineers were initially

asked to create a system that made automatic adjustments during maneuvers. While

these adjustments are extremely useful in normal flying conditions, it prevented pilots

from having as much control as they needed for extreme maneuvers during combat

simulations. The pilots felt as though the planes were fighting them and that they were

unable to push their jets to the limit that is often required in air-to-air combat. As a

result, the designing engineers were asked to alter the computerized system in the jets

to allow more control for the pilots while still maintaining the necessary automation (5).

Helmet/Visor System

While the United States’ other 5th generation fighter, the F-22, is largely an

improved version of the 4th generation fighters with added stealth capabilities, the F-35

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had to be designed largely from the ground up, particularly with its visor and sensory

communications systems. One of the earliest issues was a mechanical hardware

problem: the weight of the helmet. Because all the avionics that are normally spread

across and entire dashboard now needed to be displayed on a helmet mount, there was

an understandable increase in hardware which resulted in a heavier helmet. This may

seem minor, but it meant that during high-g turns it seriously weighed down the pilots’

heads and had serious potential for injury. The helmets would need to be redesigned to

be lighter without sacrificing their computing power (3).

The next hurdle that the engineers needed to solve was a software related issue.

Since all the information a pilot could see while wearing the HDMS was projected via

the visor, any bug posed significant problems and created a potentially life-threatening

risk for the pilot. The most substantial glitches in the early generations were a tendency

of the visual display to jitter when the plane experience turbulence, a video latency

which resulted in motion sickness and delayed reaction time, and a green glow which

would “leak” into the cockpit. This last issue was particularly dangerous as it caused a

distinct glare on the canopy which severely inhibited the pilot’s sight during night flying.

These bugs cause so much concern from the developers of the program that BAE

Systems was asked to design their own helmet design as a backup in case the original

design from Rockwell Collins couldn’t meet expectations. The software engineers were

able to improve the system in later generations of the helmet, but as it is a brand-new

type of technology, tweak and various other changed will continue to be implemented

(6).

Coordination with Other Countries and Contractors

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The Joint Strike Fighter has been a colossal undertaking and, like most

large government contracts, has involved many different civilian contractors. The lead

contractor is, of course, Lockheed Martin with the principle partners Northrup Grumman,

BAE Systems, and Pratt & Whitney. Northrup Grumman oversees a large portion of the

fuselage, stealth systems, and logistics. BAE systems also contribute to the fuselage

while also designing the STOVL system. Pratt & Whitney build the F-35’s engine, which

is the largest of its kind ever built. In total, nearly 200,000 people have been involved in

its development (1). What all this means it that, while the project is divided up amongst

several different companies, they must all meet the exact needs of the prime developer

(Lockheed Martin) and work seamlessly together or the entire program would fall apart.

If one system does not work as expected, it can cause a domino effect and place the

entire project on hold until it is fixed. In the case of the previously mentioned issues with

the visor system, and entire subcontractor project may potentially be replaced if it is not

in line with specifications.

Conclusion

The F-35 Lightning II has certainly faced its share of speed bumps during its long

and strenuous development, and only now that it is finally entering active service are the

advancements of its design made apparent. With technology advancing at an

exponential rate, the methods used to complete a project may become obsolete while it

is still being developed. The F-35 serves as a sort of microcosm of the challenges faced

by engineers when developing new technology. There is no disputing that it is the most

advanced aircraft ever built. Whether or not it was worth the cost, only the future can

tell.

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References

1. F-35 Lightning II, www.f35.com/.

2. Program, F-35 Joint Strike Fighter. “F-35 Lightning II Program.” JSF.mil > History

> F-35 Acquisition, www.jsf.mil/.

3. Zazulia, Nick. “F-35: Under the Helmet of the World's Most Advanced Fighter.”

Avionics, Avionics, 4 Sept. 2018, www.aviationtoday.com/2018/08/24/f-35-

helmet-worlds-advanced-fighter/.

4. Zazulia, Nick. “F-35 Data Fusion: How the Smartest Fighter Shares What It

Sees.” Avionics, Avionics, 4 Sept. 2018, www.aviationtoday.com/2018/09/04/f-

35-data-fusion/.

5. Lockie, Alex. “Here's Why the F-35 Once Lost to F-16s, and How It Made a

Stunning Comeback.” Business Insider, Business Insider, 18 Apr. 2017,

www.businessinsider.com/f-35-vs-f-16-15-18-lost-beaten-flatley-comeback-2017-

4.

6. Davenport, Christian. “Meet the Most Fascinating Part of the F-35: The $400,000

Helmet.” The Washington Post, WP Company, 1 Apr. 2015,

www.washingtonpost.com/news/checkpoint/wp/2015/04/01/meet-the-most-

fascinating-part-of-the-f-35-the-400000-helmet/?utm_term=.26e96a23a2de.

7. Cohen, Zachary. “The F-35: Is It Worth the Cost? - CNNPolitics.” CNN, Cable

News Network, 16 July 2015, www.cnn.com/2015/07/16/politics/f-35-jsf-

operational-costs/index.html.

8. Mizokami, Kyle. “This Chart Explains How Crazy-Expensive Fighter Jets Have

Gotten.” Popular Mechanics, Popular Mechanics, 14 Nov. 2017,

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www.popularmechanics.com/military/weapons/news/a25678/the-cost-of-new-

fighters-keeps-going-up-up-up/.