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The "Bird splitter"


Stuck

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What function does the vertical fin inside the intake of a viper have? I've asked a few dudes what it is to no avail. Something to do with going supersonic? High AOA? I know it doesn't move back and forth in there (sts) so what does it do? Any AE dudes around?

Cheers! :beer:

- Stuck

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Guest Krabs
What function does the vertical fin inside the intake of a viper have? I've asked a few dudes what it is to no avail. Something to do with going supersonic? High AOA? I know it doesn't move back and forth in there (sts) so what does it do? Any AE dudes around?

Cheers! :beer:

- Stuck

My guess is it is a surface for turbulent air to reattach to, which funnels a more even pressure distribution to the fan blades.

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.69 seconds on ask.com...

"The air intake is located underneath the fuselage, at a point just below the cockpit. The ventral location of the air intake subjects it to minimal airflow disturbance over a wide range of flight conditions and aircraft maneuvers, since the forward fuselage tends to shield the intake from the full effects of aircraft maneuvers, minimizing the effects of sudden changes in the angle of attack on airflow into the engine. At an angle of attack of 25 degrees, for example, the air flows into the intake at an angle of only ten degrees with respect to the aircraft's longitudinal axis. The lower edge of the intake lip is only 38 inches above the ground, but, surprisingly, FOD problems caused by the ingestion of runway debris into the engine have been relatively minor.

The intake is of fixed geometry type, which saves on complexity, weight, and cost. A fixed-geometry boundary-layer splitter plate separates the upper lip of the intake from the lower fuselage. There is a separation strut mounted inside the intake for additional tunnel rigidity. "

Not a Viper dude, but it sounds reasonable enough...

Chuck

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It's just a structural member (STS), the front wheel sits under there.

It doesn't serve any anti-icing purpose for the engine, but since it sits in a very-low pressure area it is itself subject to ice accumulation and has a heater.

Next question...

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It's just a structural member (STS), the front wheel sits under there.

It doesn't serve any anti-icing purpose for the engine, but since it sits in a very-low pressure area it is itself subject to ice accumulation and has a heater.

Next question...

dang hoss...you got all over that one like a SPIDER MONKEY!!!!

what does the F-16 do to prevent supersonic air from entering the inlet and causing a compressor stall?

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what does the F-16 do to prevent supersonic air from entering the inlet and causing a compressor stall?

The design of the inlet creates a shockwave which slows down the airflow to subsonic speeds. Very similar to any other fighter inlet design.

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Guest Krabs
what does the F-16 do to prevent supersonic air from entering the inlet and causing a compressor stall?

The F-16 intake is a "normal shock" intake. It creates a non-oblique shock directly in front of the intake, and once air passes through the shock, it is subsonic.

On jets like the Eagle with adjustable ramp intake, the intakes create oblique shocks (usually several) to slow the air down and get relatively even pressure distributions. There is usually a normal shock wave just inside the intake of these type anyway to get a nice pressure distribution, but since the air is slowed more gradually, the losses are less than if the air were to just go through a normal shock.

The speed regime of the Viper (usually transonic), plus the unnecessary weight/complexity added by an adjustable intake would have been more detrimental to performance than the losses from a normal shock style intake.

EDIT:: After some more research, it seems to have been added when the intake was redesigned from an NS intake to a larger, slightly different intake for the GE engines they put in the Viper. Structural rigidity seems to be the reason. Damn, I was hoping it was an elegantly simple solution to an aerodynamic problem...I guess when you're a hammer, everything looks like a nail.

Edited by Krabs
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I don't think it is logical for it to have anything to do with engine performance, cuz it continues between the inlet and the bottom of the fuselage. (either that or there is some sort of optical illusion going on in the picture that was posted above.) it wouldn't make aerodynamic sense to have an extra piece going between the inlet and the fuselage if it was there just for engine performance.

Edited by AEWingsMN
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dang hoss...you got all over that one like a SPIDER MONKEY!!!!

what does the F-16 do to prevent supersonic air from entering the inlet and causing a compressor stall?

Already pretty well addressed above, but to be clear it's the shape of the face of the inlet that causes the shock waves that yields subsonic flow, NOT the "bird splitter"

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