Any idea what these plugs/covers are doing on some older jets?

[u/zmok1]

I'm making a 3d model of a Mig-21 and got curious about them since they seemingly cover every panel but I cant think of a use for them, especially considering most other aircraft don't have them

[u/rinfodiv]

On the 2nd pic those are most likely lightbulbs. The panel is kinda clear with black on it, and the writing/lines is where there isn’t any paint. When the bulbs are on, they illuminate through the whole panel and only the lines/letters illuminate.

You remove the caps and the bulb is in it.

I know this from flying quite a few US military planes

[u/unexpanded → u/rinfodiv]

You’re right, they are bulbs- Soviet cars had the same system for dashboard lighting.

[u/potatodioxide → u/rinfodiv]

is it something like this? instead of an opening no-paint tho.
https://www.classicbulbs.co.uk/m/products/6/0/2406/bgw__352-1.jpg

[u/Epse → u/potatodioxide]

Not really, the bulbs are just normal bulbs that sit behind the panel. The panel itself is made of translucent material, painted black. So where there's no pain on the panel, light from behind shines through. Similar, but backlit not frontlit

[u/zmok1 → u/rinfodiv]

Thanks

[u/star_chicken]

option package for the deluxe model.

[u/KingZoidberg420 → u/star_chicken]

That’s the DX trim level, it also came without the passenger side mirror.

[u/pulloutforsafety]

Bulb holders for instrument backlighting

[u/idubbkny]

these are fuses

[u/Working_Passenger_32 → u/idubbkny]

No….

[u/idubbkny → u/Working_Passenger_32]

that's my assumption...

[u/Sickinmytechchunk → u/idubbkny]

The fuses sit on their own panels in most Soviet aircraft. I think the Mig21 has a panel to the right and back of the pilot, where you can't accidentally hit them.

[u/nincumpoop]

Not sure. My initial reaction was that they could be vibration isolators. But not sure.

[u/Working_Passenger_32]

Bulbs or bulb holders.

[u/New_Line4049]

Might be covers for electrical connectors to connect test equipment to various systems for maintainance work in the first pic? Western aircraft often have similar, but they're hidden away, not right on the panel. The covers just protect the connectors when not in use, keep them free of dust, dirt, debris, moisture etc.

[u/Dry_Statistician_688]

Second pic are light bulb holders. 627 or 628’s.