Skyone

The Blues and T'birds have never quite been the same since opting out of the Phantom.

UAL T38 Phlyer

Pilotpip and MMaviator:

With 2300+ hours in the Phantom, allow me:

Jet engines don't like to swallow supersonic air. Jets that are in the Mach 2-category (theoretically), have variable-geometry intakes. The Phantom has the external splitter--the forward part is fixed, but the back half (or "ramp," as we called it) is what moves, counter-intuitively, to block some of the air, as you go really fast.

I did Functional Check Flights, and at 40-48000 ft, the ramps would start to move at 500 indicated, or about Mach 1.6-1.8 (depending on OAT).

The F-14, -15, and Super Hornet all have variable-geometry intakes. The F-22's moving intakes are hidden inside the obvious intake, so as to minimize radar reflections (stealth).

The F-16 and A/B/C/D-model Hornets are fixed-intakes, and as such, are limited in Mach. I don't know the exact figure, but I would guess in the 1.3-1.6 range.

The T-38 I fly now is (in theory) limited to Mach 1.3, but in reality, with its new larger intake, is so draggy it can barely crack Mach-1.

The original B-1A had VG Intakes, but to save cost, it was eliminated from the B-1B--and that is why top speed dropped to 1.3, and subsonic on the deck.

Ryan:

The original J-79s smoked, but I flew the J-79-17E/Gs....they were smokeless (I flew F-4Gs). No kidding, F-15s and F-16s smoked more than we did. But ironically, they burned about 3% more gas than the smokers.

And that is a bunch. At brake release on takeoff, we were burning 98,000 lbs an hour. By comparison, a 747-400 is burning about 60,000.

mmaviator

thanks ual t38 phlyer

USMCFLYR

Generally you'll find the aircraft with rectangular intakes having these devices and most are in the Mach 2.0+ range (EXCEPT for the Super Bug as some have called it on here)

See above statement

Now stop it UAL T38 Pflyer!
We are already the slowest Cat IV fighter out there and now you are going to post out in cyberworld that I am even slower than I really am? MISINFORMATION! Shame on you!

USMCFLYR

Formerbuspilot

True, the Airforce and Navy/Marines should keep the F16 and F18s on the battle field and use a Real Plane (F4) to woo and impress the public!

FBP

BTDT

F-4 cockpit from the AF museum in Dayton.

AZFlyer

And the J79s are actually steam engines to power all those gauges!

crewdawg

A Viper, Rhino and the Sluf all in one picture....nice!

AZFlyer

I wouldn't be surprised if the HAF continues to fly those antiques till the wings fall off.

Nigel Tufnel

Depending on the shape and geometry of the intake it isn't required. The trick is to make sure the airflow directly hitting the front of the motor is subsonic if you can. If you can do it with the shape of the intake, you don't need moving parts, but you do lose some mdot (for our bernoulli fans).