To save myself an entire evening of trawling through websites with annoying pop-ups, I thought I would throw this one open to the floor: Which configuration would the louvres on top of the engine intake be, when parked up on the apron?
Closed. They are on springs and opened by a combination of suction from the engine and the retractable FOD screens being in the down position and limiting the air flow into the main intake.
Once the aircraft is airborne and the FOD screens are retracted and there is enough airflow into the main intakes, there is no longer enough suction force to keep the louvres open and the springs automatically close them.
Often you’ll see parked Fulcrums with big red box like guards over the louvres to allow ground crews to walk on the area if they need to.
Actually, they could be open. The mig-29’s landing gear is the control for them. When the landing gear comes down, the intakes automaticaly have covers that then close, leaving only the louvers on to for air inlet to the engines. They are actuated to open into the airflow. They louvers may close if, when the engines are shut down, a selector is switched to allow the intake covers to open allowing ground crews access for maintenance. This is a built in design by the russians for their unimproved runways. All varients have them including the Germans Mig’s. I found this info out while talking to a German Mig advassary pilot during a Maple Flag excercise.
PS: The pilots hate it![XX] Longer spoolup response.