Note: NOTHING is finished at the moment. I have started to work on propulsion and so far that's all I have updated. I still need to fix literally everything yet, so try and keep the discussion related to the propulsion write up so far until I begin to add more stuff. Also, the image is by Anemos Major.


HK7A 'Viking' Hypersonic Cruise Missile



Key Features

Weight: 18,738 lbs (8,499 kg)
Length: 32 ft. (10 m)
Diameter: 3 ft. (1.2 m)
Warhead: Various
Operational Range: 540 miles (869 km)
Engine: Solid Propellant Booster, Liquid Fueled Ramjet
Speed: Mach 5
Launch Platform(s): Mobile Launhers, Silos
Price: $6,000,000

Overview

The HK7A is a ground-launched, medium-range, all-weather, multirole, hypersonic cruise missile developed by AeroTech for the United States Military (Minnysotan Military). The HK7A is designed to be able to strike large groups of armored vehicles, key enemy emplacements or buildings, and to provide a sufficient defense from seaborne surface threats from short to medium-range. The missile has undergone several changes, going from a cruise missile that relied heavily on less-advanced guidance system to a missile that is renowned for its advanced avionics provided by Lyran Arms.

Background

Because of international treaties, such as the Missile Technology Control Regime (MTCR), cruise missiles with a warhead that exceeded 500kg could not travel more than 300km. Minnysota, however, refused to sign into this treaty, claiming that it would limit the strike capabilities of cruise missile platforms which were becoming popular in the Minnysotan Military at the time. However, due to many nations being involved in this treaty, Minnysota still found themselves importing a Russo-Indian missile: the BrahMos.

As the need for a domestic arms market grew, several arms companies in Minnysota sought to produce missiles that would exceed the BrahMos and BrahMos II not only in range, but in warhead size as well. AeroTech led this plan, with the help of two other companies that AeroTech had recently acquired. After at least two years of development and testing, AeroTech came out with the HK7 'Viking', a medium-ranged, all-weather, ship-launched, hypersonic anti-ship missile.

It was not long, however, before the need for ground and air-launched variants arose. With the threat of war in Minnysota's backyard growing, the DoD sought ways to increase the versatility of the HK7 platform so that it could be launched from bombers and a variety of ground-borne methods. AeroTech, once again, led this project. However, this time around they had foreign help. Because of increasing economic and political ties between Lyras and Minnysota, Lyran Arms offered some of its technology from their own Hellion cruise missile to be utilized on the HK7A, and possibly even the HK7 and HK7B. AeroTech decided to use the same platform as the HK7 to speed up development, and in under a year the DoD had awarded AeroTech a contract for the HK7A.


Propulsion

Initial propulsion for the missile is provided by the Mk. 72 booster used for the Standard Missile family. Because of the power offered by the booster, and the cheapness of using an already developed and popular system, the Mk. 72 proved to be a wise choice for the role of getting the HK7 missile to a point in which the ramjet would be ignited. The Mk. 72, utilizing a six-second burn length, was able to get the HK7 up to near Mach 3. The ramjet cannot engage until after the missile has reached speeds that allow ample air flow for the engine. The engine works by slowing down the supersonic flow of air into a subsonic flow inside the engine, where the air subsequently is compressed and thus pressurized and heated. After the air is compressed, it flows out the rear of the ramjet. However, the thrust created by this process is not enough to counter the drag that is also created by the missile. Thus, a liquid propellant is used and sprayed into the compressed air as it heats, causing a more powerful ignition and thus more thrust. The justification behind a liquid propellant was that the liquid propellant proved to be both simpler and more practical to apply.

[spoiler=Mk 72 Stat Block, as provided by Aerojet]Diameter: 0.53m
Length: 1.70m
Volume: 0.374 m3
Loaded Mass: 712 kg
Propellant Mass: 468 kg
Empty Mass: 244 kg
Propellant Type: HTPB-AP
Propellant ISP: 260 to 265 seconds
Burn Length: 6 seconds[/spoiler]
[spoiler=CA221 Ramjet Stat Block, as provided by AeroTech]tba[/spoiler]

Guidance and Artificial Intelligence

WIPWIPWIPWIPWIPWIP


Warhead

The warhead used by the ‘Viking’ missile is a conventional 700 kg semi-armor piercing warhead. The warhead will allow the HK7A to be fired from its launch sites along the coast and strike enemy ships that slipped past the fleet.

The missile also utilizes a warhead supplied by Lyras, the WAGAV (Wide area guided anti-vehicle warhead). The warhead contains 30 HEAT submunitions that are assigned targets individually by their own sensors while nearing the target area. Upon reaching the target area, the warhead unleashes the submunitions to navigate their way to their targets.

The HK7A also utilizes a nuclear warhead if needed for the current combat scenario.

Launch Platforms

The HK7A is launched by silos and mobile launchers. The HK7A is capable of being launched from Sharfghotten's TEL which several have been modified for testing purposes. The LY7/4072 Multiple Rocket System is also capable of harboring the missiles.

Targets

There are several main targets of the HK7A. The HK7A has the capability to serve as a ground-launched anti-ship missile to assault enemy invasion forces. In addition to ships, the HK7A can be used to assault enemy vehicles, emplacements, or even buildings of great importance. With the option for a nuclear warhead, the targets can include entire battlefields as well.

Advantages

The most notable advantage that the ‘Viking’ holds is its speed, which still tops out at around Mach 5. With its speed, the HK7A can penetrate enemy anti-missile defenses and allow its gravitational pull to guide it towards the target if it is disabled by defenses. Due to the addition of Lyran guidance systems, the missile now contains an extremely smart AI and sensors package that allows it to navigate its way to targets of great importance. The WAGAV also grants the ability to strike many different targets.

What was wrong with a solid-fuel ramjet? (not a ducted rocket, although similar)

As a cruise-missile, you would probably be better-off ditching the cruciform design, and sticking to 'conventional' unmanned-plane layout. This is largely because a cruci-design will either have:

1a. Oversized (and redundant) vertical-surfaces, causing drag, which is really bad in hypersonic rockets.
OR
1b. Undersized lifting-surfaces, requiring a greater angle of attack, spending more fuel maintaining lift, and being on the border of stalling.

And quite possably:

2. Causing --or because of-- inability to maintian roll-stability, causing severe jinking. [Usually points to designs that didn't bother defining 'up' and 'down' to a missile, just "Me", "you" and "target"]

I was told that liquid-fuel ramjets were simpler and easier to work with.

Also, I will look into the suggestions you made.