This was provided by Mr. Werner Bergmans, of Eindhoven in the Netherlands, on his site: FIGHTER PLANES and MILITARY AIRCRAFT (pictures and information). It's something of a masterpiece of understatement.
McDonnell F-101 Voodoo
The Voodoo had numerous problems during its lifetime that seemed downright scary; among these were:
Nose pitch up
At low speed or high speed/high 'G' and certain angles of attack it was thought that airflow separation occurred on the wing surfaces outboard of the wing fences. This down wash would envelop the horizontal and vertical tail surfaces and the aircraft would pitch up, airspeed would bleed off to about 110 kts.- and the stall would grow and progress inward and forward along the wing until only the inboard leading edge was producing lift. This would lift the nose of the aircraft and it would fall into an spin, oscillating between 20 and 70 degrees of pitch up.
In this oscillating stall condition the engines also stalled from lack of air induction. (In case you think this is an unusual action for a jet engine, just go out to your local jetport and watch the older 'commercials' idling on the taxi-ways in high wind conditions. Watch for the times that the wind blows across the intakes and you will see and hear the engines choking and burping and being not very happy at all.) There was not enough air across the controls to make a difference at this point so you just had to ride it out, or eject.
If you had lots of altitude and you hated parachutes the procedure was to wait for the aircraft to unload to the lowest angle of attack then deploy the drogue chute to try to keep the nose down. If your head stopped banging on the canopy you tried an engine restart and -if the engines lit- you firewalled the throttles and powered out of it until the aircraft was flying again at 230 to 350 kts., then you released the drogue. Below 15,000 feet standing orders were to eject since the Voodoo lost altitude quickly without lift. To remedy this problem the Air Force installed a hydraulic system, attached to angle of attack sensors on either side of the nose, that would not allow the stick to be pulled past specific points at specific speeds.
Nose pitch down
Similar to nose pitch up, this happened if the stick was pushed too far forward too fast at certain speeds. The flow of air over the upper wing seemed to separate in these conditions and cause the wing to loose lift. The aircraft would first fall nose first, then tumble as the tail (which still had lift) overflew the nose. The engines might stall and there might not be enough air over the control surfaces for control, but if you were quick and the engines remained lit you could catch it with the throttles it as you went through the horizontal again and fly out of it in sort of a non-spinning snap roll. The same hydraulic stick limiter designed for pitch up seemed to work as the remedy.
Inertial roll coupling
If you did a fast, large, roll at the same time as pulling G. the lower wing tip would stall outboard of the wing fence - causing an increase in the roll rate and dropping the stalled wing back - so that the roll became an asymmetrical bobble. Sort of like a snap roll again, but with no rudder fed in. If you tried reversing the controls to roll back, the ailerons would only cause drag on the stalled wing and the stall would worsen. The wing would drop until it really caught the slipstream then bounce up again... then stall again, etc. Unless you unloaded back pressure the condition would not stop, and in an oscillation or two you would find yourself in a nose pitch up condition... see above.
Missile Problems
The heat from the electronics bay cooling system exhaust ports just under the cockpits was found to be bathing the underslung port side AIM 4-D infrared missile, causing damage to the missile electronics and causing it to (I am only guessing at this point) get confused and home on the aforementioned heat vents when it was fired. I assume this because the missile would detonate two seconds after it was fired. Turbulence inducers and belly strakes to divert the heat around the missile solved this nasty problem. Luckily the nuclear rockets seemed unaffected by the heat wash during testing.
Instrument Panel Attack
It was not unknown in the early Voodoos for the instrument panel to fall into the pilots lap. This could be distracting, especially on take off, and could make it difficult to read some of the instruments unless you managed to hold the panel in just right way.
I can just see it, you ram the throttles forward and into the afterburner slot and the aircraft leaps ahead, comes to speed and you rotate and pull the wheels up in a 'jock'-like manner - the panel falls off and hits the control stick forcing it back into your lap. The AOA limiter, sensing too steep an angle of attack, hydraulically shoves the stick forward into the panel... which shoves it back... which causes the limiter to shove it forward into the panel... which shoves it back... which ....etc.
And all this time the guy in the back is asking "Excuse me pilot, just exactly what are you doing up there?" or words to that effect; and you notice for the very first time that the farmer swathing the field at the end of the runway has a small tattoo of a rose on his left shoulder; and you are trying to recall just what is rated as an acceptable impact - as seen from the point of view of the two Genies you have slung down below. They used stronger bolts, or glue, or something and fixed this cutie.
McDonnell F-101 Voodoo
The Voodoo had numerous problems during its lifetime that seemed downright scary; among these were:
Nose pitch up
At low speed or high speed/high 'G' and certain angles of attack it was thought that airflow separation occurred on the wing surfaces outboard of the wing fences. This down wash would envelop the horizontal and vertical tail surfaces and the aircraft would pitch up, airspeed would bleed off to about 110 kts.- and the stall would grow and progress inward and forward along the wing until only the inboard leading edge was producing lift. This would lift the nose of the aircraft and it would fall into an spin, oscillating between 20 and 70 degrees of pitch up.
In this oscillating stall condition the engines also stalled from lack of air induction. (In case you think this is an unusual action for a jet engine, just go out to your local jetport and watch the older 'commercials' idling on the taxi-ways in high wind conditions. Watch for the times that the wind blows across the intakes and you will see and hear the engines choking and burping and being not very happy at all.) There was not enough air across the controls to make a difference at this point so you just had to ride it out, or eject.
If you had lots of altitude and you hated parachutes the procedure was to wait for the aircraft to unload to the lowest angle of attack then deploy the drogue chute to try to keep the nose down. If your head stopped banging on the canopy you tried an engine restart and -if the engines lit- you firewalled the throttles and powered out of it until the aircraft was flying again at 230 to 350 kts., then you released the drogue. Below 15,000 feet standing orders were to eject since the Voodoo lost altitude quickly without lift. To remedy this problem the Air Force installed a hydraulic system, attached to angle of attack sensors on either side of the nose, that would not allow the stick to be pulled past specific points at specific speeds.
Nose pitch down
Similar to nose pitch up, this happened if the stick was pushed too far forward too fast at certain speeds. The flow of air over the upper wing seemed to separate in these conditions and cause the wing to loose lift. The aircraft would first fall nose first, then tumble as the tail (which still had lift) overflew the nose. The engines might stall and there might not be enough air over the control surfaces for control, but if you were quick and the engines remained lit you could catch it with the throttles it as you went through the horizontal again and fly out of it in sort of a non-spinning snap roll. The same hydraulic stick limiter designed for pitch up seemed to work as the remedy.
Inertial roll coupling
If you did a fast, large, roll at the same time as pulling G. the lower wing tip would stall outboard of the wing fence - causing an increase in the roll rate and dropping the stalled wing back - so that the roll became an asymmetrical bobble. Sort of like a snap roll again, but with no rudder fed in. If you tried reversing the controls to roll back, the ailerons would only cause drag on the stalled wing and the stall would worsen. The wing would drop until it really caught the slipstream then bounce up again... then stall again, etc. Unless you unloaded back pressure the condition would not stop, and in an oscillation or two you would find yourself in a nose pitch up condition... see above.
Missile Problems
The heat from the electronics bay cooling system exhaust ports just under the cockpits was found to be bathing the underslung port side AIM 4-D infrared missile, causing damage to the missile electronics and causing it to (I am only guessing at this point) get confused and home on the aforementioned heat vents when it was fired. I assume this because the missile would detonate two seconds after it was fired. Turbulence inducers and belly strakes to divert the heat around the missile solved this nasty problem. Luckily the nuclear rockets seemed unaffected by the heat wash during testing.
Instrument Panel Attack
It was not unknown in the early Voodoos for the instrument panel to fall into the pilots lap. This could be distracting, especially on take off, and could make it difficult to read some of the instruments unless you managed to hold the panel in just right way.
I can just see it, you ram the throttles forward and into the afterburner slot and the aircraft leaps ahead, comes to speed and you rotate and pull the wheels up in a 'jock'-like manner - the panel falls off and hits the control stick forcing it back into your lap. The AOA limiter, sensing too steep an angle of attack, hydraulically shoves the stick forward into the panel... which shoves it back... which causes the limiter to shove it forward into the panel... which shoves it back... which ....etc.
And all this time the guy in the back is asking "Excuse me pilot, just exactly what are you doing up there?" or words to that effect; and you notice for the very first time that the farmer swathing the field at the end of the runway has a small tattoo of a rose on his left shoulder; and you are trying to recall just what is rated as an acceptable impact - as seen from the point of view of the two Genies you have slung down below. They used stronger bolts, or glue, or something and fixed this cutie.
