First some clarifications required to understand the differences between ICBM, FOB and HGV.

This is an excellent figure highlighting the differences in flight profiles and trajectories of a variety of systems, from cruise missiles to ballistics to traditional LEO rocket launches.

Type 2: boost-glide hypersonic trajectory

Type 2: boost-glide hypersonic trajectory [web.archive.org]
Type 2: boost-glide hypersonic trajectory [archive.ph]

Originally posted by tasnimnews:

March, 04, 2014

Before Iran’s outstanding achievement to produce such a high-tech tool, the country had no choice but to deliver its new high-speed missiles and aerospace vehicles to foreign countries for testing purposes, which potentially increased the risk of disclosure of the indigenous research information.

tasnimnews source[web.archive.org]
2[archive.vn]

Well, North Korea has nonetheless disclosed indirectly the joint research focus on hypersonic glide vehicle (HGV) missiles!

Iran's shock-tunnel facility

Let's talk about wind tunnel testing for reentry vehicles.

The flight regimes for strategic RVs are incredibly harsh. In 30 - 45 seconds, the RV reaches speeds up to 7km/sec and ~200g acceleration loads. For reference, an AMRAAM reaches around ~1.5km/sec.

Hypersonic velocities are unattainable thru turbine-driven facilities. Instead, hypersonic tunnels store pressurized gas and blow them through expansion nozzles for short duration. The gas is then collected in vacuum chambers, like these at NASA Langley.

Expansion nozzles are key, allowing the gas to accelerate faster than Mach 1. Most of them look very similar to rocket nozzles; they can produce different flow characteristics depending on profile. Contoured nozzles are generally preferred.

As gas expands through the nozzle, its temperature drops dramatically—often to the point where it instantly liquefies. So testing gas must be preheated by thousands of degrees, typically with a plasma arc.

These capabilities are critical to reducing RV dispersion error. Of these variables TRW identified in a 1974 report, lift-related phenomena (especially uneven boundary layer transition) was the biggest contributor to inaccuracy.

The Polaris MK-1 and MK-2 RVs were tested in tunnels originally captured from Nazi Germany. Tunnels 1 and 2 were first built in Peenemünde, moved to Koche after U.S. bombings, and finally brought to White Oak, Maryland in 1946.

Given these characteristics, tunnels can be easily identified through satellite imagery. See the visible vacuum tanks, pressure lines, and gas tanks at India's Vikram Sarabhai Space Centre and Orbital's GASL shock tube (not an arc-jet).

See the visible vacuum tanks, pressure lines, and gas tanks at Orbital's GASL shock tube (not an arc-jet).[web.archive.org]
2[archive.vn]

Originally posted by Chief Technology Officer at Yonesh:

Explosive forming[web.archive.org] has been mainly used in aerospace and aircraft industry to produce large parts for which conventional tooling costs are high. It involves the discharge of explosives located at a predetermined distance from the workpiece, and water is generally used as the energy transfer medium. Parameters for controlling pressure are the amount of explosive, the charge configuration, the distance from the workpiece, the energy transfer medium, and the pressure focusing elements.

Mohammad Mahdi EsmailiMohammad Mahdi Esmaili [web.archive.org]

Originally posted by aparat.com/payeshgari.ir:

https://www.youtube.com/watch?v=Kri13r81B7M
ساخت مخازن کروی به روش انفجاری در اصفهان، ایران
561 views Dec 13, 2020

Presence of power generation (for preheaters) or heat exchangers (for cooling) may also be useful signatures. But smaller facilities may be harder to spot. The JF-12 tunnel was reportedly used to test China's hypersonic vehicles, but it appears to be a covered facility.

These facilities could be shock-tubes, which operate for extremely short durations and are used for some subscale aerodynamic tests.

Large arc-jet tunnels are very useful for RV testing.

Pictured: suspected shock-tunnel facility at Iran's Imam Hossein University.

Originally posted by tasnimnews:

Last Iranian year (ended on 20 March 2013), Commander of the Islamic Revolution Guards Corps (IRGC) Major General Mohammad Ali Jafari had unveiled plans to produce the gigantic wind tunnel inside the country, saying the local scientists should design the supersonic wind tunnel capable of producing speeds of Mach 8.​

Mach 8 Shock-tunnel facility at Iran's Imam Hossein University completed in 2014.[web.archive.org]
2[archive.is]


The type 2 boost-glide hypersonic trajectory configuration should put the Sejil-3 into the ICBM range, way over 6'000 km mark.



A Sejil-3 in ASAT configuration could place some 220 kg in a 500 km into orbit but in a direct purely ballistic ascent interception trajectory, the payload is much higher. Enough for a large ASAT warhead, either KKV or EMP.

Iran's Sejil-3/Zoljanah family. 2021 [web.archive.org]
Iran's Sejil-3/Zoljanah family. 2021 [archive.is]

HGV feasible?

Finally, after China, the DPRK is the only second superpower in the world to have indigenously mastered and developed HGV ICBMs.
But how to implement this game-changer in the current vanilla game, known to be oversimplified with its unrealistic mechanics (orbital mechanics, aerodynamics, etc)?

Until further improvements by the game's developer, it will be difficult to model these new weaponries.