Talk:Lockheed Martin X-59 Quesst

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Update request (February, 2020)

This article refers to past events in the future (and conditional) tense. Some are as old as 2017. I'm not sure when things like the wind tunnel test or design reviews actually happened, but someone who does ought to update the article. Fcrary (talk) 22:17, 8 February 2020 (UTC)[reply]

Just delivered to Lockheed Martin

Lockheed Martin posted on their social media that it just arrived to undergo structural tests. — Preceding unsigned comment added by 12.53.232.146 (talk) 21:23, 4 January 2022 (UTC)[reply]

PLdB may not exist, or at least it's not in common use

The "Design" section includes this line:

> It should create a 75 Perceived Level decibel (PLdB) thump on ground, as loud as closing a car door, compared with 105-110 PLdB for the Concorde.[6]

The source article is behind a paywall, but I'm not sure that PLdB is a scale that actually exists. The scale commonly used to measure the perceived noise level of aircraft is Effective perceived noise in decibels (EPNdB), and for general use it's sound pressure level (SPL).

Nosecohn (talk) 14:44, 24 April 2022 (UTC)[reply]

Nosecohn: I'm responsible for this addition. At the time I had an Aviation Week subscription (not anymore). It's the most reputable aviation magazine along with Flight international, and more thorough technically in my opinion. The PLdB scale was certainly quoted from the organisation behind, the NASA. A quick search gives for example https://ntrs.nasa.gov/citations/20210013118: The X-59 was designed to produce a shaped sonic boom with a Stevens’ Perceived Level (PL) of 75 dB or less across the boom carpet in a standard atmosphere.. Searching "Stevens’ Perceived Level" in wikipedia gives Stevens's power law, and "Stevens loudness" is a redirect for loudness.--Marc Lacoste (talk) 15:44, 24 April 2022 (UTC)[reply]

I found an FAA document with the formula for the perceived level of a sonic boom (PLdB), which is not the same as the perceived noise level (PNdB).

Perceived Level (PLdB) = 55 + 20 Log₁₀(ΔP / τ)

with τ the rise time (s) and ΔP the overpressure (psf)

The constant 55 was determined empirically from the following equivalence: "The subjects rating the sonic booms at Edwards judged the noise level of a boom averaging 1.69 psf overpressure and rise-time of 0.005 seconds as being equivalent to aircraft flyover noise of 105 PNdB" Roman FW (talk) 08:32, 8 August 2023 (UTC)[reply]

Outdated

at least the years given are outdated, see https://www.nasa.gov/mission_pages/lowboom/mission 47.69.137.104 (talk) 09:22, 15 November 2022 (UTC)[reply]