F-4 not horizontal stabilizer
04-25-2021, 04:45 AM
#2
Gets Weekends Off
Joined APC: Jul 2018
Posts: 1,091
Probably made them anhedral to get them out of the turbulent air caused by the wings at high angles of attack/landing. Angling them down lets them stay in smooth air and not lose any effectiveness from the turbulent air caused by the wings.
Or maybe the engineers thought it would be a cool looking counterpoint to the dihedral wing tips.
Or maybe the engineers thought it would be a cool looking counterpoint to the dihedral wing tips.
04-25-2021, 04:46 AM
#3
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Joined APC: Dec 2012
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Posts: 117
The anhedral tail was incorporated into F-4 to get horizontal stabilizers assisting the vertical stabilizer. The main vertical stabilizer was utterly useless in high angles of attack as it had work in the wake of the fuselage. By designing an anhedral tail they added more lateral surface to the aircraft.
04-25-2021, 05:51 AM
#5
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https://www.hq.nasa.gov/pao/History/SP-468/ch11-5.htm
Says this in paragraphs 5 and 6:
“A large anhedral angle (negative dihedral angle) of the horizontal tall in combination with a sharply defined positive dihedral in the outer wing panels are two conspicuous identifying features of' the aircraft. These two features are related to the position of the exhaust nozzles located only a short distance behind the low-mounted wing. To avoid impingement problems with the hot jet exhaust, the tail surfaces are mounted on an aft fuselage extension above the nozzles. As indicated by early wind-tunnel studies, the resultant high position of the horizontal tail in combination with the wing-shape parameters led to undesirable nonlinear pitching-moment characteristics at high angles of attack. The large anhedral angle, or droop, of the horizontal-tail surfaces greatly improved the pitching-moment characteristics, as well as increasing directional stability. To achieve the proper balance in dihedral effect for the integrated aircraft configuration, however, a large positive dihedral angle was incorporated in the outer panels of the wing. In addition, the wing dihedral elevated the wingtip vortexes relative to the horizontal tail and further improved the pitching-moment characteristics of the aircraft.”
Says this in paragraphs 5 and 6:
“A large anhedral angle (negative dihedral angle) of the horizontal tall in combination with a sharply defined positive dihedral in the outer wing panels are two conspicuous identifying features of' the aircraft. These two features are related to the position of the exhaust nozzles located only a short distance behind the low-mounted wing. To avoid impingement problems with the hot jet exhaust, the tail surfaces are mounted on an aft fuselage extension above the nozzles. As indicated by early wind-tunnel studies, the resultant high position of the horizontal tail in combination with the wing-shape parameters led to undesirable nonlinear pitching-moment characteristics at high angles of attack. The large anhedral angle, or droop, of the horizontal-tail surfaces greatly improved the pitching-moment characteristics, as well as increasing directional stability. To achieve the proper balance in dihedral effect for the integrated aircraft configuration, however, a large positive dihedral angle was incorporated in the outer panels of the wing. In addition, the wing dihedral elevated the wingtip vortexes relative to the horizontal tail and further improved the pitching-moment characteristics of the aircraft.”
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