Those questions don't allow for the possibility of installing louder exhausts for non-psychoanalyzable reasons... There are also degrees of loudness.
I put a slightly louder exhaust on my turbo car because the large torque jump at around 2000 rpm is/was harder to anticipate with the standard exhaust and cabin sound dampening at speed. Now the engine note is a better indicator of the impending torque jump and makes driving smoother and easier without taking my eyes off the road and onto the tachometer.
This would be fantastic. I'm trying to write an audio driver for my HT|Omega eClaro PCIe soundcard for Linux by leveraging kernel modules for cards with a similar BOM. It is mostly working, but the main hurdle is the inability to increase the volume to >= 50% of the volume in Windows. I'm setting attenuation correctly to the correct DAC registers and I can hear the opamp relay click on, but can't adjust the final gain. It sure would be great to have the Windows driver source. Worse yet, the company is unresponsive to my requests for any info (schematics, gain setting sequence, anything).
The PE6000 and the LM6000 are two shaft machines, where there is a low speed shaft on which sits the low pressure compressor and low pressure turbine (the hot and cold ends), and a high speed shaft on which sits the high pressure compressor and high pressure turbine. The two shafts are concentrically located, with the high speed shaft being on the outside. The low speed shaft is where the generator is coupled, and can be done on either the hot or cold end.
You're right that the core doesn't spin at synchronous speed but the LP shaft does. It's optimized for 3600rpm, but could run at other speeds... the machine just isn't designed for it. The LM6000 only uses a gearbox for 50Hz units while 60Hz don't need it.
The LM6000 and its variants have been in operation since probably the 1980s. I can ask around at work. I used to develop the code for the LM6000.
You're spot on that people use them for peaking, but it's a big mix. Peaking, mid-merit, and sometimes base load. There are low emissions versions as well, that keep NOx to a handful of ppm without using extra water.
People tend to use the inertia H constant (MW*s/MVA) when it comes to describing the amount of inertia that grid forming inverters and batteries can provide. Sometimes the units are simplified to seconds, which makes it easier to understand how many seconds it could provide rated power for this specific function.
Active inertia or synthetic inertia do vary power when frequency changes but the key is the dynamic behavior. They typically do so by emulating a synchronous machine by implementing something like the swing equation in the active power control (see REGFM_B1 [1]). They essentially emulate the inertia, which makes them have some damping in changing the phase angle and frequency of their voltage waveform just like a spinning synchronous generator would when resisting frequency changes due to physical inertia, resulting in an inertial active power response. This makes it easier for people to analyze because they understand the swing equation from synchronous generators.
I put a slightly louder exhaust on my turbo car because the large torque jump at around 2000 rpm is/was harder to anticipate with the standard exhaust and cabin sound dampening at speed. Now the engine note is a better indicator of the impending torque jump and makes driving smoother and easier without taking my eyes off the road and onto the tachometer.