I don't use the default aircraft or the sounds is it OK to delete them or will I have "issues"

HelloNo do not delete them many third party aircraft will use gauges from them, what harm are they doing?

Almost every payware or freeware aircraft makes use of one or two of the default sounds in FS, so it is best to leave them there. Even when things sound different on a payware aircraft it could still be using the same sound file as a default aeroplane, since the sounds are stereo placed based on the config file location of the engines. That can make them sound a little different and fool us into thinking the thing has 'custom' sounds.A good example of that would be the payware Lockheed Electra in First Class Simulation's Around the World in 80 Flights package; it uses the default DC-3 sounds, but it sounds very different from the default DC-3. Being a smaller aeroplane with the engines nearer the cockpit, the stereo placement alters the audio positioning of the engines and the way those sounds mix in with other sounds, so it has much more of a 'buzz saw' sound than the DC-3 when you are in the virtual cockpit, even though it is using exactly the same wav files.Al

I'll leave them, I have show all models checked and my hangar has like 100 planes in it so it's getting pretty crowded thats all

I have been out of flightsim for a couple of years but I seem to remember that it was possible to go into the .air file and change one value that made the aircraft into an AI aircraft, so it did not show up in the aircraft menu. Anyone remember how to do this?

I have most of my default aircraft in a file marked unused in the sim objects airplanes folder. If I should happen to need the sound files I just copy them into the plane that I have downloaded, but I usually go hunting for engine sounds on the various sim sites, for what ever aircraft I have downloaded. Then I don't have so many aircraft showing in my menu when i start my sim. Just a suggestion in case u want to try that.