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Lockheed F104 T Tail

Tue Mar 30, 2004 1:53 am

Why did Lockheed design the Starfighter with a "T" tail? I understand that the masking of the elevator by the fuselage at high AOA leads to pitch-up which might not be recoverable. Just about every other jet fighter has elevators low down on the fuselage.
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RE: Lockheed F104 T Tail

Tue Mar 30, 2004 1:59 am

I don't know why they did, but what you mentioned about the T tail being blocked by the wings/fuselage at high AOA is what contributed to Chuck Yeager crashing one.

In his NASA NF-104 with rocket assist, he did a zoom up to 114,000' I think it was. Well the control surfaces won't work in that thin an air, and he was at a high AOA. As he pinnacled the zoom and started descending at that same nose high attitude the T tail was ineffective and the F-104 was unrecoverable.

He ejected, but got badly burned and spent months in the hospital recovering.

The F-101 Voodoo also was a T tail.
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RE: Lockheed F104 T Tail

Wed Mar 31, 2004 6:38 am

At the time, it was concluded that yes, a high tail would cause pitch up. But the addition of a low tail on the F-104 was determined to lead to longitudinal and directional instability, increased drag and overall decreased combat utility, meaning maneuverability.

The F-101 was essentially subject to the same imagined deficiencies when it was designed. The XF-88 (from which the design of the -101 was taken) had a tail lower on the vertical, and I can't think of any reason why the tail position was changed other than the same reasons Lockheed used the high tail on the F-104. The -101 was a big airplane, and to make it more maneuverable, a high-mounted tail was the best way. The known problems with pitch-up were to be ironed out as the airplane went through Category I flight testing, and fitted to the production airplanes. However, McDonnell never really solved this problem.
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RE: Lockheed F104 T Tail

Wed Mar 31, 2004 10:27 am

what does AOA stand for ???
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RE: Lockheed F104 T Tail

Wed Mar 31, 2004 11:23 am

AoA is Angle of Attack
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RE: Lockheed F104 T Tail

Wed Mar 31, 2004 10:11 pm

I don't know a lot about the characteristics of the F-104 with its Tee tail, but I don't know a bit about the F-101.
Our radar squadron controlled 3 F-101B units and during the time I was there, we lost 2 airplanes and their crews due to a "pitchup". "Pitchup" occurred when the airplane reached an AOA where the wash from the wing went across the horizontal stabilizer. The airplane would pitchup and actually go end over end.

There were 2 systems that were intended to prevent the pilot from getting into a "pitchup". First, there was a stick shaker which would physically move the control stick back and forth; this was also an artificial way of alerting the pilot of an impending stall.
The second system was a stick pusher. When the airplane reached a certain AOA the system would push the stick forward. The system generated about 60 pounds of force that the pilot would have to overcome when the stick was centered. But, if the stick is not centered, the force is less.
What happened on the 2 F-101B's that we lost, the airplane was using a intercept tactic called a snap up. The airplane attacks the target from below by accelerating and then pulling up. If the target turned or was not directly above the F-101, the pilot would make corrections using the stick.
While concentrating on the making the intercept, it was possible for the pilot to override the reduced force of the stick pusher and end up with a "pitchup".
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RE: Lockheed F104 T Tail

Thu Apr 01, 2004 8:37 am

I used to work with a guy that did ALS support for F-4 and F-101's in Nam.

He told me that on the F-101 the parachute was a, forgive the civil term, "non-mel'able" item. You needed it to recover in the case deep stall.

He also told me that they used to pull the parachutes from the f-101's when they got close to their wear-out dates and stick them into their F-4's since they wheren't as critical on that airplane, compared to the F-101's.
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RE: Lockheed F104 T Tail

Thu Apr 01, 2004 11:38 am

If I remember correctly the NF-104 crash involved the engine flaming out due to lack of air, which froze the hydraulic system, leaving the horzontal stab in a very nose-up position. I cannot imagine the situation would have been much better with the horizontal tail mounted lower. Aft stick is aft stick. Once the aircraft departed, at that altitude, it was a lump with no significant aerodynamic properties. The pilot was riding a Turtle-Waxed beer bottle.

One thing is sure, though. It had to be either T-tail or cruciform tail or a major redesign would have been needed for the aft fuselage. That is just a shell around the exhaust.

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RE: Lockheed F104 T Tail

Thu Apr 01, 2004 12:36 pm

The NF-104 was a standard F-104 except it incorperated a rocket motor in the tail.The surviving one, I belive is the guate guard at Edwards.

The version I heard about what happened

Yeager was actually conduction the #2 flight of the day. The earlier flight, by another pilot had been satisfactory. But the they time Yeager went the atmosphere had heated up. This made the air less dense at altitude, so when he got up there, the less dense air was just enough to make the controls ineffective despite the reaction jets on the aircraft and he entered that flat spin, you all saw on "The Right Stuff"

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RE: Lockheed F104 T Tail

Mon Apr 05, 2004 11:37 pm

Both the F-104 and F-101 were designed as interceptors and not intended as close-in dogfighters that would generate high angles of attack. The F-4 Phantom II had a downward canted stabilator to keep the stab tips in the slipstream at high AOA.
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RE: Lockheed F104 T Tail

Wed Apr 14, 2004 9:43 pm

On his way down Yeager, after having seperated from his ejection seat, hanging on his parachute, collided with the ejection seat and got burned by red hot molten slag from the rocket booster.

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