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F-4E Auxiliary Intake Doors


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Apologies as I'm sure this has been asked and answered before, but can someone tell me when the auxiliary intake doors are open on Phantoms? I know they deploy when the gear is down, but is this always the case? If the a/c is taxiing and ready for take off are they up or down? Thanks in advance.

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Sure, they are part of the squat switch on the main gear. When gear are under load, the doors are down.

Not quite.

The Auxiliary Air Doors are controlled by landing gear handle position. Gear handle down = doors open (in air and on ground). Gear handle up = doors closed. The Auxiliary Air Doors can also open in flight if there is an overpressure of the engine compartment.

Cheers,

John

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Not quite.

The Auxiliary Air Doors are controlled by landing gear handle position. Gear handle down = doors open (in air and on ground). Gear handle up = doors closed. The Auxiliary Air Doors can also open in flight if there is an overpressure of the engine compartment.

Cheers,

John

John is correct, the landing gear handle controls the doors. I believe excessive pressure in the engine bays simply pushes the doors open inflight, I'm pretty sure there is no pressure sensor or somesuch that "tells" the hydraulics to open the doors.

The aux air doors will also snap shut with the gear down if electrical power is interrupted. They close during engine shutdown when the generators drop offline. We then pried them back open after shutdown and installed downlocks for engine oil servicing and to install the centerline safety pin if anything was installed on the centerline.

Spey powered Phantoms on the otherhand work differently, I've seen many photos of them inflight with gear up, flaps down and aux air doors open.

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John is correct, the landing gear handle controls the doors. I believe excessive pressure in the engine bays simply pushes the doors open inflight, I'm pretty sure there is no pressure sensor or somesuch that "tells" the hydraulics to open the doors.

The aux air doors will also snap shut with the gear down if electrical power is interrupted. They close during engine shutdown when the generators drop offline. We then pried them back open after shutdown and installed downlocks for engine oil servicing and to install the centerline safety pin if anything was installed on the centerline.

Spey powered Phantoms on the otherhand work differently, I've seen many photos of them inflight with gear up, flaps down and aux air doors open.

Hey Scott,

The aux air doors are indeed simply forced open by an engine bay overpressure. The USN NATOPS F-4 flight manuals provide a bit more insight to the system operation than the USAF Dash-1. The doors and actuator are designed so that an overpressure of 13.3 PSI will overcome the actuator force applied to close the aux air door with the door opening proportional to the amount of overpressure.

Cheers,

John

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Thanks for the detailed replies chaps. So basically (apart from unusual circumstances), a powered up Phantom on the runway will have the aux doors open? I ask because I'm starting a Revel-Monogram F-4E in 1/32 and the kit has them molded shut. Damn you Revell-Monogram!!!

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Thanks for the detailed replies chaps. So basically (apart from unusual circumstances), a powered up Phantom on the runway will have the aux doors open? I ask because I'm starting a Revel-Monogram F-4E in 1/32 and the kit has them molded shut. Damn you Revell-Monogram!!!

Yes, they will be open in your scenario.

Cheers,

John

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Thanks for the detailed replies chaps. So basically (apart from unusual circumstances), a powered up Phantom on the runway will have the aux doors open? I ask because I'm starting a Revel-Monogram F-4E in 1/32 and the kit has them molded shut. Damn you Revell-Monogram!!!

Parts-R-Parts make an engine bay/auxiliary intake door set for the Revell/Tamiya kit.

Cheers,

Tom

http://partsrparts.homestead.com/F4parts.html

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