Nazy
Nazy
Nazy had a lot of money. He didn’t always have money. Born in South Africa, Nazy came to America from Canada with few dollars. He worked hard and he was smart. He was a very sharp businessman.
“The misunderstanding of an un-commanded left roll appears to be widespread. It is hoped that the following information will promote thought and understanding and maybe help prevent another loss of control P-51 accident.
Engine torque at maximum power is not sufficient to torque roll the P-51D to the left during a go-around if the pilot does not allow the left wing to stall and maintains heading with the rudder and wings level with the ailerons.
An un-commanded left roll can occur if the pilot does not control yaw with the rudder. However, the roll is primarily caused by yaw-roll coupling and stalling the left wing, not torque.
The Mustang will not roll out of control to the left without first stalling the left wing. At airspeeds slightly above stalling speed, the Mustang has enough right roll authority to prevent an un-commanded left roll. Furthermore, at airspeeds slightly above stalling speed, with maximum engine power, the P-51D has enough right roll authority to perform a 360-degree right roll even with the flaps and landing gear fully extended.
The ascending propeller blades redirect the relative wind upward ahead of the left wing. The redirected relative wind increases the angle of attack over the left wing during high power settings. If the wing is already near the critical angle of attack, the additional angle of attack induced by the propeller slipstream can cause the inboard section of the left wing to stall and allow an un-commanded left roll to ensue.
The inboard portion of the wing behind the propeller stalls first. When the left wing stalls behind the ascending propeller blades, the un-commanded left roll begins. The angle of attack near the wingtip increases as the un-commanded roll progresses. The increase in angle of attack near the left wingtip results primarily from the induced relative wind opposite to the downward movement of the wingtip. The rate of roll increases dramatically when the critical angle of attack is exceeded near the left wingtip.
The Mustang has a pronounced pitch-up characteristic following a landing bounce. If the pilot does not take prompt corrective action, the nose may continue to pitch-up. When the nose has pitched up to the point that a stall is imminent, the application of power and the associated increased angle of attack induced by the propeller slipstream can stall the left wing.
Yaw-roll coupling, i.e. nose yaws left and left wing loses some lift, can cause an un-commanded left roll. The pilot must prevent the left yaw of the aircraft with right rudder to prevent an out of control left roll during a go-around. Asymmetric propeller thrust and other propeller factors cause the left yaw. The left yaw spoils some left wing lift and initiates the un-commanded left roll and the roll can stall the wing.
It is extremely important to reduce the angle of attack during a bounce recovery and go-around by lowering the aircraft nose. A reduction in angle of attack and the application of right rudder proportionate to the amount of power applied is essential to provide an acceptable margin of safety.
A nose high deck angle during a go-around and failure to maintain heading with the rudder during a go-around are ingredients for disaster.
Managing angle of attack, i.e. deck angle and maintaining heading with the rudder during a go-around or bounced landing recovery is crucial. It is much more important than the amount of power applied. The amount of power that can safely be used during a go-around is somewhat proportional to how skillfully the pilot controls angle of attack with the elevator and heading with the rudder. Of course, judicious use of engine power is recommended.
While we are discussing “torque” it may be good to talk about tire wear. Say what? Some folks say that the P-51 has so much torque that it causes the left main landing gear tire to wear faster than the right tire. It makes a good story, but the very small amount of extra weight on the left tire during takeoff, produced by torque, contributes very little to tire wear. Actually, deflection of the rudder to the right during takeoff, not torque, produces a horizontal left force on the aircraft. This left force, sometimes called translating tendency, causes more slippage and more wear on the left tire.
Many Mustang pilots have lost directional control during takeoff, swerved to the left and ran off the side of the runway. Again, torque is most often blamed. In almost all cases, the cause of the left swerve was gyroscopic precession, not torque. Gyroscopic precession is proportional to the rate of pitch change during transition from a three-point attitude to a tail up attitude. Pilots sometimes raise the tail too rapidly in an effort to see the runway over the aircraft nose and gyroscopic precession yaws the nose to the left with great enthusiasm! At that point, the pilot may have a great view of the runway out the right side of the canopy. Pilots who accept the lack of visibility over the aircraft nose until the tail has been raised very gradually do not have problems with gyroscopic precession. In fact, with no crosswind, a knowledgeable and skillful Mustang pilot can maintain runway heading during takeoff by varying the rate of pitch change and with almost no rudder pedal input at all. If the tail is raised slowly enough, the normal right rudder trim may yaw the nose to the right. Raising the tail a little more rapidly will compensate and yaw the nose to left. Reducing the rate that the tail is raised may allow the right rudder trim do the work for the pilot and bring the nose back to the right.
Understanding characteristic FACTS about this honest, wonderful airplane is essential to flying it safely, but much of what we hear about torque and “torque rolls” is FICTION.”
I’ve been busy t’day visiting back n’ forth with long-time aviation pal, Captain Ernie Lingren. We share a lot of common interests having joined the original Frontier Airlines within a few months of one-another.
The subject of the mystique that shrouded the venerable North American P-51 ‘Mustang’ came up. This led me on a trip down memory lane. So, I thought I would share a Nazy story with you.
Ernie, suggested that I should write a book. Here’s my reply:
There are a LOT of wordsmiths far better’n me. But, Cheryl has been after me to write another book. I recently finished the fourth edition to Fly the Wing. It’s with the editors now. ASA is the publisher. If you read the stories on my website you might see a book there. All my stories have a written guarantee to thwart insomnia.
I had mentioned my friend, Nazy Hirani, earlier in my visits with Ernie. Nazy died in a horrific crash of his beloved Su Su, a P-51 named for Frank Borman’s wife. Former astronaut, Frank Borman, had restored Su Su before it became part of the aviation history collection Nazy was the caretaker of…
Nazy, the great fellow he was, had a wonderful stable of aircraft. His next would have been a Chance-Vaught F-4U “Corsair.”
One glitch with this, otherwise stellar aviator, was that Nazy would not listen to P-51 expert, Larry Perkins (also based at P-19).
Larry is one of the finest aviators I’ve ever known. He is proficient in numerous warbirds. His aviation pedigree is without peer. I’ve spent countless hours sharing the flight deck with Larry in the C-47/DC-3C and think of him as the best instructor I’ve known.
Larry had checked out Nazy in his Staggerwing, T-6, and P-51. He felt more instruction needed with Su Su. Nazy resisted.
Nazy had a couple of issues that were near accidents that he escaped from. I flew with him and made a couple of salient suggestions. He said to me, as he said to Larry, “I don’t need your input, I do just fine!” This sounds arrogant, but he wasn’t really like that. Sadly, he was wrong in his personal assessment of his abilities (at least with the Mustang). I flew with him in his Staggerwing (D-17S). He did wonderfully well with that one. Also, as I mentioned, I was supposed to fly his T-6 that March afternoon in 2010. Damn!
Nazy had a lot of money. He didn’t always have money. Born in South Africa, Nazy came to America from Canada with few dollars. He worked hard and he was smart. He was a very sharp businessman.
Nazy was generous to a fault and very social in our aviation community. If only he’d paid more attention to what Larry tried telling him he and Su Su might still be gracing the Arizona skies… Damn!
Above: Billy Walker – Sergei Sikorsky – Nazy Hirani just 22 minutes before Nazy and Su Su were no more😢
March 11, 2010
I need to make a comment in this regard. Many, seemingly forever, have thought airplanes such as the P-51 “Torque Rolled” when you rammed the power on. However, you can actually perform a takeoff in the P-51 with your feet flat on the floorboards! The rudder trim is set to a nominal setting of, say 5,º perhaps a degree or two more depending on the rate the tail is raised. With the brakes set, the power is set to 35″ manifold pressure. Brakes are released then the power is pushed right up to 50″ . Down the runway you go. It is a function of proper control inputs. Adverse yaw along with airspeed being too slow causes the airplane to roll over (flying with laminar flow wings and large control surfaces is another factor). The biggest factor is gyroscopic precession which means the rate the tail is raised becomes of greatest importance.
Larry had told Nazy, emphatically, “that the Merlin engine does NOT produce enough torque to roll a properly controlled stock P-51D during a go-around. Wow, that statement should cause a reaction from those who yell, “Torque Roll” each time another of our friends loses control of their Mustang.”
Some have likened what happened at Oshkosh, when the P-51A Gerry Beck was flying struck Casey Odegaard in ‘Stang,’ to Nazy’s accident. The two are unrelated in cause.
Gerry’s right wing got under Casey’s horizontal stabilizer. Gerry tried to pull up which caused Casey’s Mustang to nose down. Here torque roll is not the issue. Look at Gerry’s Mustang. It’s turning right! Two totally different situations. The only way the two are related are that both were deadly events.
It was a very narrow escape for Casey. A restored ‘Stang’ is presently in our Airbase Arizona museum. It is made from the parts of TWENTY THREE Mustangs!
What happened to my pal Nazy was that when he landed at Stellar Airpark he skipped slightly. We all knew Nazy sat too low in Su Sun (a mistake) and did not realize that, when he raised the nose expecting a three-point touch-down he was actually climbing. In his effort to correct this he quickly raised the tail. Gyroscopic Precession then forced him in a left turn off the runway. He hit the fence tearing off part of his left wing ending upside down and backwards into Pratte’s hangar.😢
“The misunderstanding of an un-commanded left roll appears to be widespread. It is hoped that the following information will promote thought and understanding and maybe help prevent another loss of control P-51 accident.
Engine torque at maximum power is not sufficient to torque roll the P-51D to the left during a go-around if the pilot does not allow the left wing to stall and maintains heading with the rudder and wings level with the ailerons.
An un-commanded left roll can occur if the pilot does not control yaw with the rudder. However, the roll is primarily caused by yaw-roll coupling and stalling the left wing, not torque.
The Mustang will not roll out of control to the left without first stalling the left wing. At airspeeds slightly above stalling speed, the Mustang has enough right roll authority to prevent an un-commanded left roll. Furthermore, at airspeeds slightly above stalling speed, with maximum engine power, the P-51D has enough right roll authority to perform a 360-degree right roll even with the flaps and landing gear fully extended.
The ascending propeller blades redirect the relative wind upward ahead of the left wing. The redirected relative wind increases the angle of attack over the left wing during high power settings. If the wing is already near the critical angle of attack, the additional angle of attack induced by the propeller slipstream can cause the inboard section of the left wing to stall and allow an un-commanded left roll to ensue.
The inboard portion of the wing behind the propeller stalls first. When the left wing stalls behind the ascending propeller blades, the un-commanded left roll begins. The angle of attack near the wingtip increases as the un-commanded roll progresses. The increase in angle of attack near the left wingtip results primarily from the induced relative wind opposite to the downward movement of the wingtip. The rate of roll increases dramatically when the critical angle of attack is exceeded near the left wingtip.
The Mustang has a pronounced pitch-up characteristic following a landing bounce. If the pilot does not take prompt corrective action, the nose may continue to pitch-up. When the nose has pitched up to the point that a stall is imminent, the application of power and the associated increased angle of attack induced by the propeller slipstream can stall the left wing.
Yaw-roll coupling, i.e. nose yaws left and left wing loses some lift, can cause an un-commanded left roll. The pilot must prevent the left yaw of the aircraft with right rudder to prevent an out of control left roll during a go-around. Asymmetric propeller thrust and other propeller factors cause the left yaw. The left yaw spoils some left wing lift and initiates the un-commanded left roll and the roll can stall the wing.
It is extremely important to reduce the angle of attack during a bounce recovery and go-around by lowering the aircraft nose. A reduction in angle of attack and the application of right rudder proportionate to the amount of power applied is essential to provide an acceptable margin of safety.
A nose high deck angle during a go-around and failure to maintain heading with the rudder during a go-around are ingredients for disaster.
Managing angle of attack, i.e. deck angle and maintaining heading with the rudder during a go-around or bounced landing recovery is crucial. It is much more important than the amount of power applied. The amount of power that can safely be used during a go-around is somewhat proportional to how skillfully the pilot controls angle of attack with the elevator and heading with the rudder. Of course, judicious use of engine power is recommended.
While we are discussing “torque” it may be good to talk about tire wear. Say what? Some folks say that the P-51 has so much torque that it causes the left main landing gear tire to wear faster than the right tire. It makes a good story, but the very small amount of extra weight on the left tire during takeoff, produced by torque, contributes very little to tire wear. Actually, deflection of the rudder to the right during takeoff, not torque, produces a horizontal left force on the aircraft. This left force, sometimes called translating tendency, causes more slippage and more wear on the left tire.
Many Mustang pilots have lost directional control during takeoff, swerved to the left and ran off the side of the runway. Again, torque is most often blamed. In almost all cases, the cause of the left swerve was gyroscopic precession, not torque. Gyroscopic precession is proportional to the rate of pitch change during transition from a three-point attitude to a tail up attitude. Pilots sometimes raise the tail too rapidly in an effort to see the runway over the aircraft nose and gyroscopic precession yaws the nose to the left with great enthusiasm! At that point, the pilot may have a great view of the runway out the right side of the canopy. Pilots who accept the lack of visibility over the aircraft nose until the tail has been raised very gradually do not have problems with gyroscopic precession. In fact, with no crosswind, a knowledgeable and skillful Mustang pilot can maintain runway heading during takeoff by varying the rate of pitch change and with almost no rudder pedal input at all. If the tail is raised slowly enough, the normal right rudder trim may yaw the nose to the right. Raising the tail a little more rapidly will compensate and yaw the nose to left. Reducing the rate that the tail is raised may allow the right rudder trim do the work for the pilot and bring the nose back to the right.
Understanding characteristic FACTS about this honest, wonderful airplane is essential to flying it safely, but much of what we hear about torque and “torque rolls” is FICTION.”
Back to my ‘Nazy’ story… After his wing-waggle leaving the KCHD airport he did two low-passes at P19 then coming in for a landing things went badly. I believe another case of Gyroscopic Precession to be the cause when he raised the tail too quickly. Off the runway to the left, he cartwheeled into Ron Pratte’s hanger corner. Ron had 77,000 sq. ft. full of magnificent automobiles and airplanes including “Red Dog” likely the finest P-51 in existence. The crash was severe with Nazy killed and Su Su destroyed. The worst part was that his fiancé, Rosie Schulman, was on the taxi-way watching. Likely, she will never wash that image from her mind’s eye…
Those of us who knew and flew with Nazy miss him greatly. His cheerful greeting always brightened the day.
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Thank you for checking into my website. I’m delighted you liked Nazy’s story tragic as it was…