MaverickSawyer
Acolyte of the Probe
I know that there are a lot of theories out on the Internet on what happened at Reno on Friday last week, so let’s look at known facts.
KNOWN: 11 people have died, including the pilot.
KNOWN: More than 60 people were injured at various levels, ranging from minor scratches to traumatic amputations of limbs on the tarmac from flying debris.
KNOWN: Jimmy Leeward, owner and pilot of Galloping Ghost, had made dramatic modifications to the aircraft, including clipping a total of 10 feet off of the wings and installing a boil off engine cooling system.
KNOWN: Leeward called "Mayday" shortly before the trim tab separated.
KNOWN: The left elevator trim tab separated from the aircraft in the third lap shortly after Leeward had passed Rare Bear.
KNOWN: Nine seconds later, Ghost impacted into the tarmac in front of the VIP boxes, leaving an 8 ft. long, 3 ft. deep dent in the tarmac.
KNOWN: The tail wheel deployed in the course of the sudden maneuver.
In addition, I will discuss 5 assumptions that I have seen on this or other forums, or on the media.
ASSUMPTION #1: Leeward was unconscious, and not in control of the aircraft. (Courtesy of Hangar Talk Forum)
ASSUMPTION #2: Ghost was doing 475 mph at the time of the crash. (Courtesy of Yahoo News)
ASSUMPTION #3: Ghost suffered elevator flutter, which was the reason for the "Mayday" call. (Courtesy of Hangar Talk Forum)
ASSUMPTION #4: Leeward suffered a medical event that caused him to call "Mayday." (Courtesy of Urwumpe)
ASSUMPTION #5: The seat failed, and Leeward was unable to reach the controls. (Courtesy of FOX News, n122vu)
Let's look at the second assumption first.
Ghost had just passed Bear to take 3rd. We know that Bear was doing 450, so the assumption that Ghost was doing 475 mph is valid.
Next, the FOX News theory...
In the thread Vintage plane crashes into crowd at Reno air races, this theory arises on page 4, near the middle. It is a possibility, although a less likely one than the first assumption, which will be covered last.
The assumption that Urwumpe proposes, Leeward suffering a medical problem, leading to a "Mayday" call, will have to be determined by the NTSB, and they may have a hard time doing so, due to the amount of destruction caused by the impact. However, modern forensics can perform amazing data analysis, so we cannot discount this as a possibility.
Next, the assumption that I proposed, the elevator flutter, has more evidence than Urwumpe's. Veteran air race fans reported hearing a buzzing sound that was not related to an engine, and occurred just before the pitchup of Ghost. Once again, we have to wait for the NTSB to announce the results of their investigation. Again, we cannot discount this possibility.
Finally, the assumption that Leeward was unconcious.
Time for a little physics. Everything is easier if done in metric, so I will demonstrate the proper technique for those of you that have not taken college level physics of motion.
take your given figures:
475 miles/hour; 9 seconds from pitchup to impact; ~3/4 of a circular path taken by Ghost before impact.
Convert the velocity from miles/hour to meters/second using unit conversion.
(If you want to follow along, but do the math for yourself, skip the next couple of lines. If you want to learn how to do this, follow along.)
Start with your given: 475 Miles/Hour.
Multiply by 5280 feet/1 mile. Miles cancel out, leaving you with 2508000 feet/hour.
Multiply by 1 hour/60 minutes. Hours cancel out, leaving you with 41800 feet/minute.
Multiply by 1 minute/60 seconds. Minutes cancel out, leaving you with 696.6666... feet/second.
Multiply by 12 inches/1 foot. Feet cancel out, leaving you with 8360 inches/second.
(Still with me? Good. Now we convert to metric.)
Multiply by the conversion factor 2.54 cm/1 inch. Inches cancel, leaving you with 21234.4 cm/second.
Mulitply by 1 meter/100 cm. Cm cancel, leaving you with the velocity of 212.344 meters/second.
Whew! Lot of math there. But wait, it gets more complicated!
Now that we have the velocity, we must make an assumption that this velocity will remain the same until the fatal impact. (In reality, this would be the starting velocity, from which energy losses due to drag, gravity, and the actual manuever will remove velocity. For the sake of this post, however, we will neglect these losses.)
At 212.344 m/s, how far does the Ghost travel in 9 seconds?
Simple: V=D/T: Velocity equals Distance divided by Time.
Solving for Distance, we get D=V*T.
Inserting the values V=212.344 m/s and T=9s, we get a distance of:
1911.096 meters.
So how does this help us in understanding the accident? It allows us to find the G's Leeward was experiencing in the cockpit.
Take the distance we just found, and place it on the ~3/4 circle that the plane traced as it flew up, over, and then into the ground (and the VIP boxes).
3/4 Circumfrence=1911.096 meters.
Find the full circumfrence of that circle:
Circumfrence = 2548.128 meters.
Since Circumfrence=2πr (FYI: that's a pi symbol: 3.1415927...)
r=405.55... meters.
Still with me? Good. Prepare for some physics...
Radial acceleration (pulling G's in an airplane) is found using the formula:
A=V^2/r, or Acceleration equals the velocity squared divided by the radius of the circle. This is where the constant velocity makes this much easier.
Insert the values we have gathered so far into the equation and we get:
111.18 meters per second squared. Divide this by the force of gravity at the surface of the Earth, Fg=9.80665 m/s^2, and we get the final answer we have been working towards these last few minutes, the G's being pulled.
Leeward was pulling...
11.34 G's.
So, why does this matter? After all, the Thunderbirds and Blue Angels pilots routinely pull that much. The difference is, they are expecting it. They are ready for the onset of the G's. Leeward was caught off guard, and without a G-suit, he passed out. This is backed up by the experience of Bob Hannah, who was flying Voodoo, another Mustang, when the trim tab fell off during the 1998 race. He pitched up at more than 10Gs, and did not come around until several seconds after the G's backed off. Leeward was under continous load until impact. This is backed up by a photo of the cockpit of Ghost that was taken at the top of the climb. With a clear view through the canopy, the picture showed Leeward's head pinned against the instument panel, below the lip of the cockpit walls. Therefore, Leeward was passed out, and would never feel the crash.
Assumption #1 is TRUE. Physics doesn't lie.
Most importantly, what caused the trim tab to fail? The NTSB has the final say, but my (highly uneducated) opinion is the following chain of events occured:
1. Some emergency is detected in the cockpit by Leeward. He calls "Mayday", and swings wide to conserve energy, intending to trade airspeed for altitude before coming in for landing
2. Keeping the curve going, he heads for the inside of the course, and begins to level out. However, he crosses over the turbulent wake of the aircraft that have already been by. This turbulence causes an already overstressed trim tab on the left elevator to fail.
3. With the departure of the trim tab, the control stick snaps forward with enough force to drag Leeward along, causing him to bash his head on the forward console. He passes out.
4. The aircraft now performs a 11+G pitchup. Leeward remains unconcious as the plane executes a snap roll to the right, and begins to descend towards the crowd. At some point, the G forces deploy the tailwheel, resulting in the famous image taken of the left side of the aircraft as it plunges to the ground.
5. The plane impacts into the tarmac. A "mass casualty situation" ensues.
I am interested to see what the outcome of the NTSB report is, and pray that this is not the end of the Reno Air Races.
God bless those who died or were injured that day.
KNOWN: 11 people have died, including the pilot.
KNOWN: More than 60 people were injured at various levels, ranging from minor scratches to traumatic amputations of limbs on the tarmac from flying debris.
KNOWN: Jimmy Leeward, owner and pilot of Galloping Ghost, had made dramatic modifications to the aircraft, including clipping a total of 10 feet off of the wings and installing a boil off engine cooling system.
KNOWN: Leeward called "Mayday" shortly before the trim tab separated.
KNOWN: The left elevator trim tab separated from the aircraft in the third lap shortly after Leeward had passed Rare Bear.
KNOWN: Nine seconds later, Ghost impacted into the tarmac in front of the VIP boxes, leaving an 8 ft. long, 3 ft. deep dent in the tarmac.
KNOWN: The tail wheel deployed in the course of the sudden maneuver.
In addition, I will discuss 5 assumptions that I have seen on this or other forums, or on the media.
ASSUMPTION #1: Leeward was unconscious, and not in control of the aircraft. (Courtesy of Hangar Talk Forum)
ASSUMPTION #2: Ghost was doing 475 mph at the time of the crash. (Courtesy of Yahoo News)
ASSUMPTION #3: Ghost suffered elevator flutter, which was the reason for the "Mayday" call. (Courtesy of Hangar Talk Forum)
ASSUMPTION #4: Leeward suffered a medical event that caused him to call "Mayday." (Courtesy of Urwumpe)
ASSUMPTION #5: The seat failed, and Leeward was unable to reach the controls. (Courtesy of FOX News, n122vu)
Let's look at the second assumption first.
Ghost had just passed Bear to take 3rd. We know that Bear was doing 450, so the assumption that Ghost was doing 475 mph is valid.
Next, the FOX News theory...
In the thread Vintage plane crashes into crowd at Reno air races, this theory arises on page 4, near the middle. It is a possibility, although a less likely one than the first assumption, which will be covered last.
The assumption that Urwumpe proposes, Leeward suffering a medical problem, leading to a "Mayday" call, will have to be determined by the NTSB, and they may have a hard time doing so, due to the amount of destruction caused by the impact. However, modern forensics can perform amazing data analysis, so we cannot discount this as a possibility.
Next, the assumption that I proposed, the elevator flutter, has more evidence than Urwumpe's. Veteran air race fans reported hearing a buzzing sound that was not related to an engine, and occurred just before the pitchup of Ghost. Once again, we have to wait for the NTSB to announce the results of their investigation. Again, we cannot discount this possibility.
Finally, the assumption that Leeward was unconcious.
Time for a little physics. Everything is easier if done in metric, so I will demonstrate the proper technique for those of you that have not taken college level physics of motion.
take your given figures:
475 miles/hour; 9 seconds from pitchup to impact; ~3/4 of a circular path taken by Ghost before impact.
Convert the velocity from miles/hour to meters/second using unit conversion.
(If you want to follow along, but do the math for yourself, skip the next couple of lines. If you want to learn how to do this, follow along.)
Start with your given: 475 Miles/Hour.
Multiply by 5280 feet/1 mile. Miles cancel out, leaving you with 2508000 feet/hour.
Multiply by 1 hour/60 minutes. Hours cancel out, leaving you with 41800 feet/minute.
Multiply by 1 minute/60 seconds. Minutes cancel out, leaving you with 696.6666... feet/second.
Multiply by 12 inches/1 foot. Feet cancel out, leaving you with 8360 inches/second.
(Still with me? Good. Now we convert to metric.)
Multiply by the conversion factor 2.54 cm/1 inch. Inches cancel, leaving you with 21234.4 cm/second.
Mulitply by 1 meter/100 cm. Cm cancel, leaving you with the velocity of 212.344 meters/second.
Whew! Lot of math there. But wait, it gets more complicated!
Now that we have the velocity, we must make an assumption that this velocity will remain the same until the fatal impact. (In reality, this would be the starting velocity, from which energy losses due to drag, gravity, and the actual manuever will remove velocity. For the sake of this post, however, we will neglect these losses.)
At 212.344 m/s, how far does the Ghost travel in 9 seconds?
Simple: V=D/T: Velocity equals Distance divided by Time.
Solving for Distance, we get D=V*T.
Inserting the values V=212.344 m/s and T=9s, we get a distance of:
1911.096 meters.
So how does this help us in understanding the accident? It allows us to find the G's Leeward was experiencing in the cockpit.
Take the distance we just found, and place it on the ~3/4 circle that the plane traced as it flew up, over, and then into the ground (and the VIP boxes).
3/4 Circumfrence=1911.096 meters.
Find the full circumfrence of that circle:
Circumfrence = 2548.128 meters.
Since Circumfrence=2πr (FYI: that's a pi symbol: 3.1415927...)
r=405.55... meters.
Still with me? Good. Prepare for some physics...
Radial acceleration (pulling G's in an airplane) is found using the formula:
A=V^2/r, or Acceleration equals the velocity squared divided by the radius of the circle. This is where the constant velocity makes this much easier.
Insert the values we have gathered so far into the equation and we get:
111.18 meters per second squared. Divide this by the force of gravity at the surface of the Earth, Fg=9.80665 m/s^2, and we get the final answer we have been working towards these last few minutes, the G's being pulled.
Leeward was pulling...
11.34 G's.
So, why does this matter? After all, the Thunderbirds and Blue Angels pilots routinely pull that much. The difference is, they are expecting it. They are ready for the onset of the G's. Leeward was caught off guard, and without a G-suit, he passed out. This is backed up by the experience of Bob Hannah, who was flying Voodoo, another Mustang, when the trim tab fell off during the 1998 race. He pitched up at more than 10Gs, and did not come around until several seconds after the G's backed off. Leeward was under continous load until impact. This is backed up by a photo of the cockpit of Ghost that was taken at the top of the climb. With a clear view through the canopy, the picture showed Leeward's head pinned against the instument panel, below the lip of the cockpit walls. Therefore, Leeward was passed out, and would never feel the crash.
Assumption #1 is TRUE. Physics doesn't lie.
Most importantly, what caused the trim tab to fail? The NTSB has the final say, but my (highly uneducated) opinion is the following chain of events occured:
1. Some emergency is detected in the cockpit by Leeward. He calls "Mayday", and swings wide to conserve energy, intending to trade airspeed for altitude before coming in for landing
2. Keeping the curve going, he heads for the inside of the course, and begins to level out. However, he crosses over the turbulent wake of the aircraft that have already been by. This turbulence causes an already overstressed trim tab on the left elevator to fail.
3. With the departure of the trim tab, the control stick snaps forward with enough force to drag Leeward along, causing him to bash his head on the forward console. He passes out.
4. The aircraft now performs a 11+G pitchup. Leeward remains unconcious as the plane executes a snap roll to the right, and begins to descend towards the crowd. At some point, the G forces deploy the tailwheel, resulting in the famous image taken of the left side of the aircraft as it plunges to the ground.
5. The plane impacts into the tarmac. A "mass casualty situation" ensues.
I am interested to see what the outcome of the NTSB report is, and pray that this is not the end of the Reno Air Races.
God bless those who died or were injured that day.