ESSM / SLAMRAAM

[Seragina]

Whelp, I've been saying for long timr Nammo's Thor will be the basis for near future missiles along with sub-caliber final stage missile to get the range and agility to shoot down fighters at 1000+km.

There was also this post wrt NAMMO.
https://www.secretprojects.co.uk/threads/aargm-vfdr-missiles.3411/post-450763

But 400km from a ground launch seems ridiculous. Their charts show about 3x range of SRM, so I'd guess nearer 150km unless the size is very different and it has a long booster motor as well as a separate SFRJ 2-stage. If they made it full 6.55m length but same diameter and a SFRJ second stage, then it will have a very good range and still quad-pack. He does reference A2A in the video in your 2nd link, so maybe the 400km is for that.

The rule of thumb is untouchable but what's wrong is the baseline being used. The baseline being 70' tech. We are looking at 1.5-2x improvements from both fuel and fightpath optimization.
The interesting thing is when compared to other existing airbreathing hypersonic solution, and if all publications are indeed thruthfully then according to my calculation it does look like they got sufficient fuel volume. The problem remains with the booster (required operational inlet speed) and the burning rate. I got a difference of 1.8x. I dunno what to make of this extra amount.

It might be a minor thing and I am not an expert in propulsion and the nuances of ground launch vs air launch, but isn't air launch proportionally more beneficial towards SRMs compared to ramjets, provided that the ramjets (on ground launch) are boosted to sufficient speeds for the ramjet to operate? Air launch means that an SRM escapes the "ground tax" (using propellant in dense air), whilst a ramjet still have hundreds of seconds to be propelled at higher altitudes at maximum sustained thrust, even when ground launched, whereas an SRM burns for 5-10 seconds, with a higher fraction of their burn time at low altitude. It genuinely wouldn't surprise me if ground launched SRMs got more than 3-4 times range increase.
They also spoke about the ramjet running for 350-400 seconds. The meteor reaches out to 100km in under 90 seconds, whilst the ramjet is running the entire time. If the kinematics are somewhat similar then this 300-400 km range honestly seems plausible. That's not to say I'm not equally doubtful of their ability to fit that sort of propellant mass in an ESSM/AMRAAM-ER-sized missile, but I suppose having a chin-mounted inlet provides a lot more length to fit propellant into, compared to the side inlets of the meteor. Honestly, I'm really just excited to see what they come up with.

It's about (burning) thrust, hence, acceleration. All things equal the rule of thumb remain valid.
Whether airlaunched or surface launch operational speeds remain the same.
Inlet operational speed range cannot be exceeded (undermined) without starving the motor, similary once balance of drag and speed have been met it cannot reach higher speeds. The excess fuel saved from airlaunch compared to surface launch contributes to longer cruise burn. The differene is with the integrated booster which by design is strong but short lived. The few seconds saved here probably amount to a few to ~15 nm of difference at best depending on speed.

 

[Seragina]

I went through the calculation steps again and used more precise range and drag calculations. That solved the discrepancy I had above. The difference now is ~10% from a perfect result. This is a high error margin for my taste. But since this is based on a lot of uncertain details I think this is quite good for an error margin. So their claim is plausible when compared to other existing solution of this technology. We'll have to wait longer for more details to be released that makes more sense than what we got now.

 

[Sferrin]

I went through the calculation steps again and used more precise range and drag calculations. That solved the discrepancy I had above. The difference now is ~10% from a perfect result. This is a high error margin for my taste. But since this is based on a lot of uncertain details I think this is quite good for an error margin. So their claim is plausible when compared to other existing solution of this technology. We'll have to wait longer for more details to be released that makes more sense than what we got now.

Out of curiosity what speed are you assuming?