Afterburner

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Afterburner

Postby Bubblehead » Thu May 08, 2014 10:57 pm

To those jet jockies:

Why do fighter jets have to use their afterburners during ground takeoffs. I live near Miramar MCAS in San Diego, CA and I often watch F18s take off with afterburners blasting. Can F18s take off without the afterburner? I believe Miramar MCAS's runway is long enough for a safe take off. I even watched a Mirya AN 225 land and take off at this airbase. Certainly they'll be saving on gas by not using the afterburners during take off.
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Re: Afterburner

Postby PhantomTweak » Fri May 09, 2014 2:24 am

A lot depends on 2 factors, the t/o weight of the aircraft, and the pilot's sense of fun :)
Believe it or not, at max gross, an FA-18 F or G actually does need the AB for proper t/o roll including room for abort and proper climb rate.

7.5.2 Normal Takeoff. Predictions for takeoff performance (nosewheel liftoff speed, takeoff speed,
takeoff distance, and abort speed) should be calculated in the preflight brief based on aircraft
configuration and expected ambient conditions. These predictions are based on the following
technique: both engines stabilized at 80%N2 rpm, simultaneous brake release and throttle advance to
MIL or MAX, ½-aft (2.5 inches) stick rotation at the predicted nosewheel liftoff speed. This technique
should be used when ambient conditions and performance predictions warrant minimizing takeoff roll.
Review these numbers prior to takeoff

Begin
the takeoff roll by releasing the brakes, advancing the throttles from IDLE to MIL, and checking EGT
and RPM. If an afterburner takeoff is desired, further advance the throttles to MAX (full forward).
Check for proper afterburner light-off as indicated by both nozzles opening. As the aircraft accelerates
during the takeoff roll, track runway centerline using small rudder pedal inputs (e.g., NWS
commands). NWS is the most effective means of directional control during takeoff. Differential...

CAUTION
Takeoff performance is greatly affected by gross weight, center of gravity,
power setting, stabilator position, and ambient conditions. Under adverse
conditions (e.g., hot, heavy, and forward CG), takeoff speeds may be
significantly higher than those routinely seen at nominal conditions.
Knowing the aircraft’s predicted takeoff performance should prevent a
high speed abort in what is a normally functioning aircraft.

All copied directly from A1-F18EA-NFM-000, the FA-18 F/G NATOPS manual.

Don't even know if all this babbling is helpfull or not, but there it is...
Pat☺
Have fun, fly high, far, and free!
Pat
2S7, Chiloquin OR Image
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Re: Afterburner

Postby Bubblehead » Fri May 09, 2014 9:14 am

It's very helpful. Now I know there's more to what it takes for the jet fighter to take off. Thanks.
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