Saber Stall/Spin Characteristics
- Thread starter Zipper730
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Very few swept wing jets had "good" stall characteristics, at least by the standards of us lowly straightwingers.
As far as know swept wings are what they are, they have to be flown differently. 1972 Sacramento Canadair Sabre accident - Wikipedia
From A&AEE trials of North American Sabre (F-86A) FU279 and FU296:
Stalling characteristics. The straight stalling characteristics of the aircraft appeared to be completely innocuous. In the flaps and undercarriage up configuration slight elevator and tail buffering developed at about 110 kts I.A.S. and the aircraft stalled at about 105 kts I.A.S. At the stall the nose dropped mildly and a mild tendency for either wing to go down slightly was easily counteracted by using aileron. The slots were observed to open under these conditions at about 155 kts I.A.S. and close again during recovery at about 180 kts I.A.S.
A great number of stalls under applied 'G' were made in turns to port and starboard at 25,000 ft. and 40,000 ft. in connection with the high altitude manoeuvrability quantitative test programme. Certain inconsistencies were noted in the stalling characteristics under these conditions, but in general the aircraft tended to pitch nose down out of the turn at speeds up to about 250 kts I.A.S. and flick either into or out of the turn at higher speeds. There was a very considerable increase in intensity of tail buffeting in comparison with the straight stall and at the higher speeds this buffeting developed well before the stall e.g. in a turn at 370 kts I.A.S. at 25,000 ft. buffeting developed at 4.2 'G' (accelerometer reading) and the aircraft stalled at 5.0 'G' (accelerometer reading).
Recovery from the stall was generally immediate on easing the stick forward. However, in one instance when the aircraft was stalled in a turn to starboard at 230 kts I.A.S. at 40,000 ft. it flicked to port, and when the stick was eased forward and a small amount of starboard aileron was applied the aircraft again flicked violently to port. Application of starboard rudder failed to arrest the flick to port and all controls were then centralised. The aircraft then pitched violently nose down producing a reading of -0.5 'G' on the damped Kollsman accelerometer, before recovery was finally effected.
Stalling characteristics. The straight stalling characteristics of the aircraft appeared to be completely innocuous. In the flaps and undercarriage up configuration slight elevator and tail buffering developed at about 110 kts I.A.S. and the aircraft stalled at about 105 kts I.A.S. At the stall the nose dropped mildly and a mild tendency for either wing to go down slightly was easily counteracted by using aileron. The slots were observed to open under these conditions at about 155 kts I.A.S. and close again during recovery at about 180 kts I.A.S.
A great number of stalls under applied 'G' were made in turns to port and starboard at 25,000 ft. and 40,000 ft. in connection with the high altitude manoeuvrability quantitative test programme. Certain inconsistencies were noted in the stalling characteristics under these conditions, but in general the aircraft tended to pitch nose down out of the turn at speeds up to about 250 kts I.A.S. and flick either into or out of the turn at higher speeds. There was a very considerable increase in intensity of tail buffeting in comparison with the straight stall and at the higher speeds this buffeting developed well before the stall e.g. in a turn at 370 kts I.A.S. at 25,000 ft. buffeting developed at 4.2 'G' (accelerometer reading) and the aircraft stalled at 5.0 'G' (accelerometer reading).
Recovery from the stall was generally immediate on easing the stick forward. However, in one instance when the aircraft was stalled in a turn to starboard at 230 kts I.A.S. at 40,000 ft. it flicked to port, and when the stick was eased forward and a small amount of starboard aileron was applied the aircraft again flicked violently to port. Application of starboard rudder failed to arrest the flick to port and all controls were then centralised. The aircraft then pitched violently nose down producing a reading of -0.5 'G' on the damped Kollsman accelerometer, before recovery was finally effected.
- Thread starter
- #5
The Canadair Sabre Mk.1 & 2 correspond almost exactly to the F-86A-5 and F-86E-1; as for the Mk.5, it has the 6-3 wing from the little I read about it -- those wings have no slats. I'm guessing they were prone to pitch-up...
So the slatted designs F-86A/E, and early F's were fairly docile in their handling characteristics...
It is all relative, not docile enough for me to be flying one any time soon. The removal of leading edge slats and addition of internal fuel didn't help things but as I understand it you have to fly to the given "numbers".
from wiki.
The Sabre's swept wings and jet engine produced a flying experience that was very different from the propeller-driven fighters of the time. The transition from props to jets was not without accidents and incidents even for experienced fighter pilots. Early on in the jet age, some US manufacturers instituted safety and transition programs where experienced test and production pilots toured operational fighter squadrons to provide instruction and demonstrations designed to lower the accident rate.[24]
Additionally, the ongoing technical development and long production history of the F-86 resulted in some significant differences in the handling and flying characteristics between the various F-86 models. Some of the important changes to the design included the switch from an elevator/stabilizer to an all-flying tail, the discontinuation of leading edge slats for a solid leading edge with increased internal fuel capacity, increased engine power, and an internal missile bay (F-86D). Each of these design changes impacted the handling and flying characteristics of the F-86, not necessarily for the better. In the case of the solid leading edge and increased internal fuel capacity, the design change produced increased combat performance, but exacerbated a dangerous and often fatal handling characteristic upon take-off if the nose were raised prematurely from the runway.[25] This 'over-rotation' danger is now a major area of instruction and concern for current F-86 pilots. The 1972 Sacramento Canadair Sabre accident resulting in 22 fatalities and 28 other casualties was a result of over-rotation on take-off.
- Thread starter
- #7
Nor for me -- that said, I've never flown an airplane before, so that's not much of a bar...
FLYBOYJ
"THE GREAT GAZOO"
I worked part time for a guy who owned 2 of them and everything posted was just about right. One of Al's birds had drop tanks, the stall speed was higher but the aircraft was a bit more stable through it's vertical axis. The Saber is built like a tank and truly one of the best fighters ever built.
Peter Gunn
Master Sergeant
I couldn't agree more.
Lesson learned. Most jets of the next generation were designed with not enough low speed elevator authority to rotate the nose until flying speed was reached.
Some of the early century series fighters didn't get this quite right, witness the infamous "Super Sabre dance" and the "Voodoo bronco", but this feature resulted in transition to the stick aft takeoff tecnique. During the takeoff roll the stick is held in the full aft position until the nose begins to rise, then it is smoothly and rapidly moved to the normal climb attitude position. This takes a little experience to get right. But then so does everything else in a jet fighter. It was sometimes amusing and occasionally chilling to watch RAG students with very little time in the F4 make the occasional shaky takeoff.
My student and I had just landed over a 4 plane flight of F4s waiting for takeoff, and she (who had been doing really well) had botched this landing badly. We were supposed to be done for the day, but she wanted another try, so she pulled off to the taxiway and asked Tower if we could sit there for a couple minutes, then taxi back for another circuit. Tower approved and cleared the jets for takeoff, leaving us with a ringside seat near the departure end to watch them go. Well the nugget driving #4 apparently wasn't paying attention, as his nose started to rise...and kept rising...and rising! Super Sabre dance redux! WTF? GTFOH!! We taxied hurriedly away from ground zero with our jaws hanging open as he staggered down the runway at about twice the normal pitch attitude, walking on his afterburner flames. If he had the presence of mind to realize what was happening before he pulled the gear up, he could have dropped back on the runway, dropped his hook, and taken the overrun gear. Too late now. As he traversed the length of the runway, he was seen to gain a little altitude, lower the nose a degree, sink back a little, then rise again, lower another degree, and start to get ahead of it a little bit at a time. He went sailing through the tops of the mangrove thicket at the end of the runway and disappeared from sight, but NOT from sound. His burners could still be heard over our idling O200 Continental, and about 15 seconds later he reappeared in the distance going straight up.
Tower advised we were through flying for the day and flying club operations were shut down UFN, as an incident investigation would be conducted. Sure enough, CFR (who had scrambled at the first sign of a problem) escorted us back to the club, and #4 came back and landed, followed by the other 3.
Gotta hand it to the Instructor RIO in the back seat talking that nugget out of trouble. When the only flight control you have is your voice and your experience, you EARN that "Silver Tongue Award" they give out in cases like this. Your "sweat hog" flight suit you wear for everyday bank and yank gets another silver tongue patch sewn on it, but not your "presentation" flight suit you wear when the bigwigs are on base. If you saw a RIO out in the fleet back in the day wearing a Silver Tongue patch, you knew he'd been a RAG instructor.
- Thread starter
- #12
I didn't know that -- I do remember hearing that the F3H Demon had quite a lot of elevator authority even as it was being catapulted (it was possible to actually bounce the nose).
I would have just assumed that you wait until VR and only then start pulling back.
Actually, I've noticed that the F-4 had a tendency for overrotation -- particularly depending on load-out.
The Demon, despite its later arrival, was essentially of the first generation jet class, and like others of the class, had a powerful elevator and an anemic engine.
True enough, that big stabilator came alive rather quickly, and with an aft CG, could make for a lively rotation. But at least it wouldn't let you rotate early and delay your liftoff and eat up your runway. By the time pilots were hauling heavy ordnance loads, they generally had enough experience to handle it.
The Lighting has been seen many times taking off and pointing skywards with afterburners on and climbing vertically. Is that a sort of trick, building up huge speed on take off and shortly after to allow it to be done?
Any reasonably athletic aircraft can do that. In the dense air of the lower atmosphere, the fastest energy gain happens as deep in ground effect as pilot's gonads and aircraft configuration allow. My first F4 ride included a max performance takeoff and (supposedly) unrestricted climb. When we went past the mirror landing (meatball) device after takeoff and gear retraction the waveoff lights on top were higher above my canopy rail than they had been when we taxied past it heading out. We were so low that if we'd had drop tanks or ordnance hung, they'd have been scraping the ground. A road on an elevated dike crossed the departure path about 200 yards beyond the runway, and the driver of a deuce and a half truck paused, looked our way, then proceeded across with us about 300 yards away and coming on at over 350 knots. We were so low and so close he looked right past us. I lost my vision shortly thereafter, and when I got it back several seconds later all I could see was blue, an AI indicating 80° nose up, and an Airspeed/Machmeter showing 385 knots. Altimeter was winding up at an insane rate. As we went through 9K, the pilot goes "Shit!!", my shins bang the bottom of the instrument panel, every loose item in the cockpit (my hands included) is stuck to the canopy, my helmet klunks against the canopy, and my vision starts to go pink, then red. In the distance, ATC is saying "Climb cancelled! Maintain one zero thousand! Traffic conflict! Acknowledge!"
"Roger, tally, we're gonna bust one zero." from the front cockpit. As my vision comes back, we're in a steep wing over looking down at a Bonanza diving away toward the civilian airport downtown. Clueless civilian blundering into a military control zone, not talking to anybody.
That's called "getting the flight off to a good start".
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