Cruise Missiles Research Articles

Vulnerability Assessment for Naval Ships against Air-Explosive Impulses: Modified Damage-Extent Method Incorporating Structural Capacity

Abstract This study introduces an enhanced damage-extent method that incorporates the structural load-bearing capacity of the hull to assess the vulnerability of naval ships to explosive loads. This vulnerability assessment predicts the area of damage to the hull structure and calculates the probability of onboard equipment experiencing functional losses due to the explosive load, thus allowing various design alternatives to be evaluated. The proposed methodology improves upon traditional damage-volume-based approaches, such as damage-radius and ellipsoid methods, by considering the hull's structural stiffness and intrinsic damage resistance. It integrates the hull's structural resistance to the load, enhancing the damage assessment process for both the hull and equipment. This approach facilitates damage prediction for different hull designs by comparing the allowable impulse with the explosive pressure. In assessing the functionality loss and vulnerability of the equipment within the damaged hull, the network of equipment functions is considered. An anti-ship cruise missile with a sea-skimming trajectory is investigated as the explosive charge, with procedures established to simulate its trajectory and impact location on the hull. Hundreds of potential internal and external explosion points are generated, predicting the explosive pressure at each location. The shock wave, including incident overpressure, reflection pressure, and quasi-static gas pressure, is converted into impulses, taking into account the configuration of hull compartments to accurately predict these pressures and equivalent impulse. The resulting impulse is compared with the intrinsic damage capacity of each compartment's structure to assess potential damage. System network and fault tree analysis evaluate the loss of function and vulnerability of equipment within the damaged hull. Finally, the proposed capacity-based damage extent method demonstrates more accurate damage assessment compared to traditional methods, overcoming the limitations of damage-radius and ellipsoid approaches by considering hull strength

Research on optimization of the synthesis endo-tetrahydrodicyclopentadiene from dicyclopentadiene

Endo-tetrahydrodicyclopentadiene (endo-THDCPD) serves as a crucial precursor in the synthesis of exo-tetrahydrodicyclopentadiene (exo-THDCPD), the primary component of JP-10 , a single-component hydrocarbon fuel utilized for high-performance cruise missiles, rockets, and supersonic aircraft propulsion. Endo-THDCPD was synthesized through the hydrogenation reaction of dicyclopentadiene (DCPD) using a Pd/C catalyst. In this study, optimal conditions for the hydrogenation process have been thoroughly investigated. Specifically, the reaction is carried out in n-hexane solvent at a reaction temperature of 90 °C, a total H2 pressure of 0.5 MPa, a reaction time of 4 hours, and a catalyst/DCPD mass ratio of 10%.

Формування траєкторії керованих літальних апаратів

Currently, there is an increased interest in the creation of flight control systems for unmanned aerial vehicles, which, taking into account real conditions, would ensure its trajectory and thereby determine the effectiveness of the use of the aerial vehicle. Aircraft navigation, in particular ballistic cruise missiles, requires the formation of high-precision control in order to achieve both final results and local optimization tasks at each of the flight stages: take-off, departure to set trajectories, maneuvering, etc. The development of admissible control and its optimization by computer-mathematical methods of modeling and optimization is a time-consuming process and requires significant expenditures of various types of resources. An element of the effectiveness of such a mathematical apparatus for guaranteeing and increasing the reliability and effectiveness in achieving the set goal is the speed of calculations, which, in turn, requires the simplification of the mathematical model by obtaining functional dependencies for calculating the flight trajectory, avoiding complex mathematical calculations. The complete working model for calculating the desired trajectory of the aircraft will be determined by the specified control functions and will be provided by a system of partial differential equations with time, and the necessary parameters for calculating all aerodynamic forces and moments are tabular data in most cases. A mathematical model for solving the task of forecasting navigation for such complex controlled systems is proposed to be carried out using two coordinate systems: starting and speed. Moreover, all calculations of the velocity vector, which depends on the net effect of three aerodynamic forces acting on the aircraft, should be carried out in the speed coordinate system, and coordinate control of the flight along the entire dynamic trajectory should be determined in the starting system

To compete or strategically retreat? The global diffusion of reconnaissance strike

The reconnaissance strike complex is synonymous with modern military power, and prominent realist theories would have predicted rapid proliferation after its successful debut in the Gulf War. Instead, the complex has proliferated slowly. To explain this puzzle, we theorize that interstate security threats significantly impact proliferation, but not in the way traditionally presumed. Although the literature on weapons proliferation has largely assumed a monotonically increasing relationship should hold between the capabilities of a state’s adversaries and a state’s own capability, we draw from the economics literature and game theoretic insights from political science to argue that the relationship should resemble an inverted-U. When states have rivals with moderate reconnaissance strike capabilities, they have security incentives to compete with them. However, when states face highly advanced adversaries, it becomes more difficult to escape or match their competition, making symmetrical acquisition less appealing. While most prior research focuses on narrower aspects of the reconnaissance strike complex like missiles or smart bombs, we test our theory on a novel dataset tracking country-level acquisition of eight aspects of the complex from 1980 to 2017: Ballistic missiles; bombers; cruise missiles; fighter aircraft; intelligence, surveillance, and reconnaissance assets; precision-guided munitions; satellites; and submarines. We find strong support for our inverted-U argument. States that have rivals with moderate reconnaissance strike capabilities have over double the reconnaissance strike capabilities themselves than states that have rivals with very low or very high capabilities. Our findings hold for broader measures of the complex that closely proxy a state’s general military capabilities, narrower measures of the complex, and alternative measures of general military sophistication, indicating our theory has broad applicability. This article explains why some states invest heavily in conventional capabilities despite an already-large lead over their adversaries, and why other states instead opt to invest in alternatives rather than balancing symmetrically.

The Iranian-Israeli conflict is one of the main threats to international security

The article analyzes a brief history of the relationship between two regional powers — Iran and Israel, the roots and causes of their confrontation, and the features of waging the so-called “hybrid war” between them at the present stage. The author pays attention to describing the situation of the relatively small Jewish community of Iran, the activation of all Tehran's proxy forces in the Middle East (Palestinian Hamas, Yemen's Ansar Allah, Lebanese Hezbollah, etc. anti-Israel groups in the region). Particular attention is paid to the fi rst ever direct military confrontation between Iran and Israel, which resulted in an exchange of missile and drone attacks in April 2024. Restraint in the actions of Israel's allies represented by Washington and other Western countries during the Iran-Israeli confl ict and the mutual disinterest of Tehran and Tel Aviv in inciting large-scale hostilities are noted. The author believes that the level of confrontation between Iran and Israel could be signifi cantly reduced if the IDF military operation in the Gaza Strip were stopped and peace negotiations on a Middle East settlement were resumed. The article provides a comparative analysis of the military potentials of Iran and Israel and examines possible scenarios for further developments in the region. The author believes that Tehran has become the greatest beneficiary of the latest aggravation of the situation in the Middle East. The process of recognition of the State of Israel, which had been outlined in previous years, was practically thwarted; Iran strengthened its authority as a fi ghter for a just solution to the Palestinian problem in the Arab and Muslim world, and noticeably weakened Israel’s position in the region and in the international arena. In conclusion, the author concludes that the Iran-Israeli confl ict represents one of the main threats to regional and international security. This is explained by a number of factors, the most important of which is the presence of nuclear missile weapons in Israel and a triad of means of delivering them to targets, as well as the fact that Iran is armed with ballistic and cruise missiles, long-range drones and can also create nuclear weapon. The Iran-Israeli confl ict presents an equation with many unknowns. The threshold of tension between these countries could be reduced by the cessation of Israel's military operation in the Gaza Strip, the resumption of peace negotiations on resolving the Palestinian problem in various formats, and a return to the nuclear deal with Iran (JCPOA) by Washington.

Experimental and Numerical Determination of the Aerodynamic Characteristics of a Cruise Missile Model

A model of a cruise missile was tested in symmetrical air flow in a low-speed wind tunnel of the Military University of Technology (Warsaw, Poland). A virtual model of the missile was developed, and the geometry of the computational domain was built in the CAD environment of the ANSYS computational software suite. The domain was discretised in the ANSYS Meshing application, creating a hybrid computational mesh. Boundary conditions were determined in the ANSYS Fluent application, and physical (turbulent compressible flow) and numerical models were selected. Calculations were performed for three different turbulence models – Spalart-Almaras, realizable k-ε, and SST k-ω – and the results were compared to find the model providing the best convergence with in-tunnel measurements.

VERSION OF LOITERING MUNITIONS CLASSIFICATION BASED ON THE STATE-OF-THE-ART AND TRENDS ANALYSIS

At present, objects of the rocket and space industry and strategic nuclear forces of the leading countries of the world, as well as other expensive infrastructure objects, can be attacked by air attack units belonging to the newest class of weapon — loitering munitions. This type of weapons combines low cost and easy development and production, which makes them available for illegal armed formations and the conduct of hybrid warfare. According to their design features and performance characteristics, loitering munitions occupy a place between cruise missiles and unmanned aerial vehicles. To analyze the threats from this type of weaponry to objects of the rocket and space industry and other sectors of the economy and to determine potential countermeasures, a version of classifying modern and future loitering munitions is proposed based on their operating range and typical destruction objectives. Specifically, loitering munitions can be divided into anti-aircraft munitions and munitions to target ground objectives. The latter category is additionally divided into tactical, medium-range, and long-range loitering munitions. Technical features, typical munitions and development trends are given for each category of loitering munitions. The de- pendence of the loitering munition warhead mass on the launch mass was studied, and the effect of the installed engine type was shown. The dependence of the main engine type on the loitering munition category is identified, which is a determining factor that forms the configuration and performance characteristics of a munition. An analysis of modern armed conflicts shows that loitering munitions are gaining more and more importance for successful accom- plishment of combat missions. It is shown that depending on the enemy, nature of hostilities, technological and economic capabilities of the parties to the conflict, loitering munitions of different categories can be used. Examples are given of the prominent role of loitering munitions in such conflicts as the current conflict in Yemen and the recent war in Nagorno-Karabakh. Based on the proposed classification of loitering munitions and the experience of their tactical employment in armed conflicts of the 21st century, a vision was formed for the development of loitering munitions for the Armed Forces of Ukraine.

Countering Unmanned Aircraft Systems – A Multi-Domain Effort

Abstract In the last decades, the proliferation of the unmanned aircraft systems (UASs) has altered the modern battlefield and the need to counter these inexpensive, flexible, and expendable systems has become paramount. UASs come in a variety of sizes and capabilities, the larger ones may achieve effects compared to a cruise missile and the smaller systems are difficult to detect as they manoeuvre across the battlefield in order to successfully conduct tactical-level strikes. So it is a must to understand that countering this kind of threat is a shared and joint responsibility and the approach has to be a comprehensive one, covering a broad spectrum of military, civil and legal perspective on this subject matter. Moreover, as it is clear that there is a need to employ multi-domain solutions to nullify the UAS threat, nations should aim to achieve technical interoperability and standardization given by a common doctrine and operating procedures.

Static and dynamic characteristics of supersonic cruise missile with damaged wing

AbstractAccurately evaluating the aerodynamic performance of the missile with damaged structures is very important for the subsequent flight control strategy. At present, few researchers have studied the aerodynamic characteristics of damaged supersonic cruise missiles. Based on CFD (computational fluid dynamics) solutions and the dynamic derivative identification method, the differences in static and dynamic characteristics between the damaged and undamaged models are compared. The results indicate that when the extent of damage increases, the change rate of drag coefficient at larger AoA (angle-of-attack) is greater than that at the smaller AoA. On the contrary, the change rate of lift coefficient at larger AoA is smaller than that at smaller AoA. Meanwhile, the absolute value of the static pitch moment decreases, but the absolute value of the roll moment increases. Damage causes a change in the absolute values of the pitch and roll dynamic derivatives, and the dynamic derivatives do not vary monotonically with the increase of AoA. The turning point occurs at about $\alpha$ = 5°. The areas of the hysteresis loops of the pitch-roll coupling moment increase, which makes the dynamic coupling characteristic between the pitch and roll directions increase. Finally, the maximum allowable damage extent of the missile wing that can achieve static trim is obtained and validated by controlling the deflection of the four rudders.

OPTIMIZATION OF THE ISOMERIZATION REACTION OF ENDO-TETRAHYDRODICYCLOPENTADIENE INTO EXO-TETRAHYDRODICYCLOPENTADIENE

The key ingredient in JP-10 fuel (Jet Propellant 10), known as Exo-tetrahydrodicyclopentadiene (exo-THDCPD), played a crucial role in powering high-performance cruise missiles, rockets, and supersonic aircraft. This essential component was synthesized by converting endo-tetrahydrodicyclopentadiene (endo-THDCPD). In this study, exo-THDCPD was synthesized through the isomerization reaction of endo-THDCPD using an AlCl3 catalyst. The optimal conditions for the isomerization reaction have been thoroughly investigated such as the influence of the solvent, reaction time, temperature reaction, and mass ratio of starting materials. In these conditions, the desired product was obtained up to the conversion rate of 98.5% and the selectivity of 99.5%. Moreover, the specific properties of exo-THDCPD were also thoroughly studied in this article.

RECONNAISSANCE AND STRIKE SYSTEMS IN NETWORK-CENTRIC WARFARE

The article reveals the essence of the concept of network-centric warfare, outlines the main requirements for network-centric military control systems when they are used in modern wars (combat operations) to ensure automated control of high-tech armed forces. This article examines the current state and prospects for the development of intelligence-strike systems. Reconnaissance and strike systems are key elements of modern military operations, providing the ability to conduct reconnaissance missions and conduct strikes against enemy targets. The article analyzes modern reconnaissance and strike systems, including unmanned aerial vehicles, cruise missiles and other means. Their technical characteristics, possibilities and limitations are studied. Also considered are the main challenges and trends that affect the development of intelligence-strike systems, such as the expansion of the use of artificial intelligence and the increase of autonomy of systems. This article examines the role of intelligence-strike systems in the context of network-centric warfare. In modern military conflicts, where information technology and network interaction play a key role, reconnaissance and strike systems are becoming an integral part of strategic planning and combat effectiveness. The article analyzes the impact of network-centric warfare on intelligence and strike systems. The main characteristics and requirements for these systems for effective operation in the conditions of network warfare are considered. The latest technologies that can increase the effectiveness of intelligence-strike systems in such conditions are being investigated, including artificial intelligence, data analytics and autonomy. Based on the analysis, the article provides recommendations for the further development of reconnaissance and strike systems. Ways to improve their effectiveness, to ensure better coordination between reconnaissance and strike functions, and to ensure greater security and resistance to enemy countermeasures are proposed. The presented material should be used both by the management staff and scientists of the armed forces when developing operational-tactical requirements for network-centric management systems of military purpose, as well as by management bodies when evaluating their functioning in order to choose possible ways to implement certain measures to improve their ability to perform tasks as assigned.

Retaliating against cyber-attacks: a decision-taking framework for policy-makers and enforcers of international and cybersecurity law

Cyber warfare is a reality taking on increasing importance. Governments, state-sponsored actors, and non-state sponsored actors have used cyber-attacks as the “weapon of choice” due to their specific characteristics. Cyber-attacks can be highly targeted and focused, even tailored to a specific unit or system, providing limited to no physical destruction (unlike a cruise missile) and potentially resulting in no loss of life. There are several incident response frameworks and approaches that an organization can implement to enhance its security posture. Usually, these will address specific adverse events such as computer security incidents, which in turn are limited in scope and coverage, typically within an organization. Nations have made limited effort in confronting severe cyber-attacks targeting and/or threatening them, as well as in preventing these attacks from being launched. In this work, we identify and discuss a decision-taking framework that may allow state actors to adopt new options against severe cyber-attacks, not always complying with international norms. Such options are neither encouraged nor supported. On the contrary, we discuss them so that the international community is made aware of such potential frameworks. More specifically, by defining clear thresholds, roles, and responsibilities, by introducing a structured chain of command, and by identifying the potential of certain actions, policy makers can recognize an extended decision space that may lead to unpredictable deterrence options against cyber-attacks.

Analysis of the state of development of the issue of protection of critical infrastructure facilities using engineered munitions

The Russian-Ukrainian war at the stage of full-scale invasion has shown that one of the most difficult tasks of ensuring the survivability of troops and the functioning of critical infrastructure is to protect them from high-precision weapons, namely cruise and ballistic missiles and unmanned aerial vehicles.
 The experience of warfare shows that the existing domestic air defense systems do not fully defeat air targets, while highly effective foreign-made air defense systems are supplied in insufficient quantities, and the created mobile fire groups to destroy air targets are not always effective. In these circumstances, it is advisable to consider new integrated approaches to the use of various types of weapons in the active defense of troops and critical infrastructure against air attack.
 The complex construction of a system of active defense of troops and critical infrastructure against air attack is possible with the use of several types of weapons. Based on the analysis of the enemy's use of missiles of various classes and Shahed-type attack unmanned aerial vehicles, the paper proposes the use of engineered munitions as one of the means of defeating moving air targets that fly low at low speed. The use of special engineered ammunition will make it possible to increase the range of low-flying air targets and increase the likelihood of their defeat. This will improve the effectiveness of the existing system of protecting troops and critical infrastructure from air attack.
 The paper analyzes the use of air attack weapons of the Russian Federation against troops and critical infrastructure facilities of Ukraine, substantiates proposals on the expediency of using engineered ammunition as an element of building a system of active protection of troops and critical infrastructure facilities from air attack, and presents their principle of operation and possible applications.

Rethinking change in Japan's security policy: punctuated equilibrium theory and Japan's response to the Russian invasion of Ukraine

ABSTRACT Change in Japanese foreign and security policy has long been characterized as “incremental”. However, Japan’s response to Russia’s 2022 invasion of Ukraine provides an opportunity to reconsider this paradigm. In the aftermath of the 2014 annexation of Crimea, then-Prime Minister Abe Shinzō chose not to put Crimea on the agenda, prioritizing instead relations with Russia. However, Prime Minister Kishida Fumio responded to the 2022 invasion by increasing ties with NATO, promising to double Japan’s military spending, and acquiring capabilities that were once considered off-limits, including cruise missiles. This dramatic policy shift is analyzed using punctuated equilibrium theory (PET). We find that the 2022 invasion became a focusing event, shifting public and elite opinion in unison. Where Crimea was played down, Ukraine was clearly linked to Asia, to a possible invasion of Taiwan, and as a threat to the entire liberal international order under which Japan had prospered. We argue that overall change in Japan’s policy has not been continuous, rather, focusing events, such as Iraq’s invasion of Kuwait, 9/11, and the 2012 “national security crisis” have precipitated fundamental change. Thus, we conclude that PET provides a better understanding of policy change than incrementalism.

Height Control of Supersonic Sea‐Skimming Missiles Based on Online Parameter Identification

This paper presents a height control approach employing real‐time parameter identification for supersonic sea‐skimming missiles. Firstly, an integrated identification technique based on the Unscented Kalman filter was established for supersonic cruise missiles. The method facilitates the online identification of aerodynamic and thrust coefficients while simultaneously estimating state variables such as height and angle of attack. Secondly, a backstepping control method was designed to regulate the height of sea‐skimming missiles. Control commands were generated based on online identification and state estimation, as well as the additional angle of attack caused by wind being compensated. The simulation results show that the proposed height control method achieved a high level of precision when operating in the challenging conditions of ultralow‐height sea skimming, despite the presence of parameter uncertainties, measurement inaccuracies, sea wave disturbances, and wind effects.

Necessary Explanations on Merits of Solving Problem of Optimizing Construction of Air Defense System of Surface Ships Formation in Case of Attack Threat of Anti-Ship Cruise Missiles

A number of publications related to the improvement (optimization) of the air defense system (AD) orders of surface ships (SS) in the threat of attacks by anti-ship cruise missiles (ASCM)was developed by a group of authors (Galiy V.A., Ivanishchev S.N., Bukri V.N.) and submitted for the consideration of the specialists. The publications were evaluated by experts and this article presents a discussion on the merits of solving the problem of optimizing the construction of an air defense system of the surface ships formation in case of attack threat of anti-ship cruise missiles taking into account some questions and comments.

The war in Ukraine: the failure of deterrence

With the Russian invasion of Ukraine, it became evident that the longstanding American deterrence policy that had worked during the Cold War failed. In February 2022, Russia started a war of conquest against its neighbor, and the United States and its European allies were unable to prevent it. America’s deterrence broke down for two main reasons. First, successive American Presidents failed to act when Russia used its brute military force against its neighbors. In 2008, Russia attacked Georgia and captured two provinces, proclaiming them “independent states.” In 2014, Russia attacked Ukraine, annexed Crimea, and established military control over two other provinces in Donbas, and announced their “independence.” In both cases, the United States and its European allies imposed mild trade sanctions on Moscow, most of which they soon repealed. The most remarkable act in this regard was sponsored by the Obama administration, which in 2011-2012 pushed hard for Russia’s accession to the World Trade Organization by bullying Georgia not to veto Moscow’s application. The second, more significant cause for the failure of deterrence was America’s refusal to invest in a new generation of strategic weapons. Since the end of the Cold War, the United States has developed very little in terms of upgrading its nuclear arsenal and creating new delivery systems. At the same time, Moscow invested hundreds of billions of dollars in developing and deploying new long-range cruise missiles, new hypersonic missiles, and a new generation of intercontinental ballistic missiles.

АНАЛІЗ АКУСТИЧНИХ СИГНАЛІВ ЗАСОБІВ ПОВІТРЯНОГО НАПАДУ

This paper analyzes the acoustic signals of aerodynamic aerial attack weapons used by the Russian Federation during a full-scale invasion. These include strike unmanned aerial vehicles, cruise missiles, jet and turboprop aircraft, and helicopters. It has been established that the time for observing an acoustic signal is limited by the speed of the vehicle. For high-speed targets (cruise missiles, airplanes), it averages 10 s, and for slower targets, 40-50 s. The Welch periodogram method was used to extract the spectral characteristics of acoustic signals. It is shown that the acoustic signal of propeller-driven vehicles is the sum of harmonic and noise-like broadband components, and that of turbojet-powered vehicles has a predominantly noise-like structure with several narrowband components. It was found that at the moment of maximum convergence, the signal spectrum has the greatest width. The characteristic change in the frequency of harmonic components associated with the Doppler effect is investigated. It can be used to estimate the parameters of motion and identify the vehicle. By correlation analysis of acoustic signals, it was found that broadband components have a noise-like structure. An acoustic signal for the case of simultaneous over flight of different types of vehicles was formed by adding records of different acoustic signals. It is shown that the characteristic spectral characteristics of all objects are preserved on the frequency-time plane. The results of the analysis can be used to build mathematical models of acoustic signals and to develop methods for processing signals of aerial attack weapons in an acoustic airspace monitoring system. Keywords: aerial attack weapons; acoustic signal; spectrogram; acoustic monitoring system; harmonic component.

PLACEMENT OF ROBOTIC MISSILE DEFENSE COMPLEXES ON AN UNMANNED AIR VEHICLE

Objects of critical infrastructure of Ukraine need a multi-level anti-missile defense system, which should protect against various types of missiles with a flight range of several tens to several hundreds of kilometers. Timely detection of missiles allows for a number of measures aimed at interception and destruction of targets, the use of radio-electronic warfare, the installation of interfering and obstructing obstacles in various ranges of radio waves, as well as the inclusion of optical and thermal traps. The use of robotic complexes placed on aerostats increases the effectiveness of modern surface-to-air missile system (SAMS) many times over in the fight against low-flying targets with massed strikes of cruise missiles. The location of radar at an altitude of several kilometers ensures the detection range of low-flying targets several times greater than that of ground-based radar. This is of particular importance for SAMS when firing at targets beyond the radio horizon. The transfer of data about the location of the target from the radar of the air carrier to the air defense system and its illumination and guidance radar (at least the approximate location) provides the opportunity to bring the anti-missile to the point of inclusion of its homing head. It is proposed to modernize the radar with an active phased antenna array used on fighters to increase the range and installation on airships and balloons. This will ensure the effectiveness of defense against missile attacks, detection and tracking of up to 100 targets at distances of about 40...400 km. At the same time, the weight of the radar within the range of 200...500 kg and the dimensions of the antennas up to 1 meter are permissible for installation on large balloons. Countries for which attacks of various types of missiles are a real threat need a multi-level anti-missile system, in particular, using robotic complexes placed on air carriers. Keywords: anti-missile defense, radar station, balloon, airship.

Hydrogen hypersonic combined cycle propulsion: Advancements, challenges, and applications

In the progress toward net zero, two propulsion systems are attracting increasing interest, one based on energy stored in batteries, and the other based on energy stored in hydrogen. In between the applications where hydrogen energy storage has more advantages, there is hypersonic propulsion, which is the object of this perspective. Hypersonic vehicles are aircraft or missiles able to travel at speeds above Mach 5. There are four main types of hypersonic vehicles, spaceplanes, glide missiles, cruise missiles, and aircraft. While glide missiles generally do not need propulsion, cruise missiles, and aircraft are designed to sustain hypersonic speeds for extended periods. They use advanced propulsion systems, which include scramjets, relying on the forward motion of the vehicle to compress incoming air for combustion, and featuring supersonic combustion. While scramjets work well at hypersonic speeds, they must be integrated with other propulsion systems, such as ramjets, rockets, and turbojets, to move back and forth from zero speed. Spaceplanes have been designed so far by using only rockets or integrating rockets and turbojets for better operation in the atmosphere. Spaceplanes' operation in the atmosphere could also be further improved by using ram/scramjets. Point-to-point hypersonic travel for civil applications, which is the focus of this work, requires significant advantages in jet propulsion systems that have to work over different regimes, from subsonic to transonic to supersonic to hypersonic. The work reports on the challenges of hydrogen hypersonic combined cycle propulsion.