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Not to be confused with aerospike nozzles. This is about the big pin-like rod in front of ICBM nose cones.

This answer (from Space) about aerospike nose cones notes that one of the potential advantages of the aerospike nose cone is to considerably decrease noise from the supersonic boom. In this comment the author evokes projections for the Concorde, dropping noise from 110 dB to 60-70 dB, that is 15 to 30 times quieter.

Noise from the supersonic boom, as the story goes, is what ultimately killed the Concorde: most nations forbid overland flight because of it, limiting it to ocean flights. So there would be clearly benefits from this.

Have there been any supersonic planes using this design that flew? Are there projects to do so that are currently active? Otherwise, why not?

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    $\begingroup$ "Noise from the supersonic boom, as the story goes, is what ultimately killed the Concorde" It isn't the only thing that killed the Concorde though. The Concorde was an incredibly uncomfortable aircraft from the passenger perspective. Airbus wasn't making parts, the avionics were antiquated, ticket prices were extremely high, Airbus didn't make replacement parts anymore, and nobody wanted to fly it after AF4590. You could say though that noise "killed the future of the super-sonic airliner"... $\endgroup$ – Ron Beyer Apr 17 '19 at 13:36
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    $\begingroup$ @RonBeyer True. What I meant is, it is often said to be (one of) the fundamental cause(s): had it not be barred from flying overland, there would have been many more orders, at least dozens. This would have made it more profitable and easier to maintain and keep pieces for it. Peak oil would have still hurt it, but maybe it would have been big enough to still stick around, instead of wasting away on a few, dying lines. it would have still have stopped flying at some point, but with the market open, others would have followed - so "killed the future of the super-sonic airliner" is indeed better $\endgroup$ – Eth Apr 17 '19 at 14:12
  • $\begingroup$ Noise, fuel consumption, the land overflight ban, and a fatal accident were four different nails in the coffin. $\endgroup$ – bogl Apr 17 '19 at 14:35
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    $\begingroup$ @RonBeyer Concorde was always sold out, except understandably for a few days after AF4590, until the very last flight; that means prices were too low. The main economic problem was AF/BA only put a few of them in service due to perceived route viability; once a flight attendant discovered it was possible to charter them, though, the fleet was booked solid flying all over the world, and public flights actually became a side business. They could still be flying today as charters if parts were still available. $\endgroup$ – StephenS Apr 17 '19 at 17:18
  • $\begingroup$ Actually project bongo and bongo 2, were the issue. The brilliant military of the '60s decided they needed to fly low altitude supersonic flight over a midwest city several times per day for months on end, just to see what would happen because they thought sonic booms maybe useful as a weapon. This operation was the primary reason for banning supersonic flight over land. Though they really just irritated people and broke a couple windows they did collect some usable data on shock wave magnitude and dissipation. $\endgroup$ – Max Power Aug 25 '19 at 6:37
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There are no historical aircraft with an aerospike nose, at least, none that I remember, and none that I could find after 30 mins of research. I'm not sure if there are any planned projects using it, but I doubt there are, given the purpose of aerospike noses - aerospike noses really only have one main purpose - to streamline a blunt body. This is commonly used in missiles and such (especially in SLBMs), where height/length is a constraint - a slender, sharp nose is very long, so to save height, those missiles are fitted with an aerospike that telescopes out. The flat plate at the end of the aerospace forms a detached bow shock, which makes the airflow "see" the blunt body as having a different, more streamlined shape, reducing drag. Here's a visual of that happening:

enter image description here

Image source - https://iopscience.iop.org/article/10.1088/1742-6596/1276/1/012031/pdf

However, the bow shock generated by a drag reducing aerospike causes more drag and a heating than the oblique shock generated by a slender nose of the same length. For SLBMs, a long, sharp nose is obviously out of question (well, you could have a telescoping sharp nose, but that would be heavy), but for aircraft, length really isn't a concern, you can make the nose as long as needed. Therefore, it doesn't really makes sense for an aircraft to have an aerospike nose.

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