F-35 in Live Free or Die Hard
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I just rented Live Free or Die Hard. In it is a scene where Bruce Willis, aka John McLain, takes on an F-35B. It's, as expected, ridiculous. I just think it would be fun for those who have seen it to point out the structural, systems, and performance issues with the Hollywood version of the F-35 (the F-35H, perhaps?). I have at least two on the top of my head, but I'll reserve them.
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The twin cannons on the lower fuselage is the one thing that comes to mind.
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I didn't think it was that far off from the X-35B. They missed a few big things, but they observed alot of other little details. Not bad for a bunch of hollywood folks...definately up to Hollywood standards.
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I just saw the movie over the weekend and it wasn't to bad. I also watched Transformers and the F-22's were really hot!
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Corsair1963 wrote:I just saw the movie over the weekend and it wasn't to bad. I also watched Transformers and the F-22's were really hot!
So was Bumblebee !!!
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Lightndattic wrote:The twin cannons on the lower fuselage is the one thing that comes to mind.
Yeah, that was one of mine. They also used a 2-door upper lift fan door, which is X-35 stuff. The production version will have a single aft-hinged door. My responsibility on the F-35 is with hydraulics, so that's what I first noticed.
I didn't really pay attention to the markings on the tail, and I'm curious whether the instruments were correct. I also thought the gun(s) fired longer than the capacity of the magazine, but I don't really know the capacity. How quickly would something FOD'ing the ULF cause a catastrauphic failure? It seemed to be a slower process on the movie than I would expect. Does the canopy come off during ejection? Do you think the airplane could actually maneuver under a bridge like was done in the movie?
Overall I was pretty impressed at Hollywood's attempt. The F-22 on Transformers was good, too.
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msupepper wrote:Lightndattic wrote:The twin cannons on the lower fuselage is the one thing that comes to mind.
Yeah, that was one of mine. They also used a 2-door upper lift fan door, which is X-35 stuff. The production version will have a single aft-hinged door. My responsibility on the F-35 is with hydraulics, so that's what I first noticed.
I didn't really pay attention to the markings on the tail, and I'm curious whether the instruments were correct. I also thought the gun(s) fired longer than the capacity of the magazine, but I don't really know the capacity. How quickly would something FOD'ing the ULF cause a catastrauphic failure? It seemed to be a slower process on the movie than I would expect. Does the canopy come off during ejection? Do you think the airplane could actually maneuver under a bridge like was done in the movie?
Overall I was pretty impressed at Hollywood's attempt. The F-22 on Transformers was good, too.
The F-35 adopted the Harrier method of ejection which is lining the transparency with explosives (yeehaa!). I think the reasoning behind this is that during STOVL ops, the milliseconds waiting for the canopy to clear the ejection path are too precious.
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LMAggie wrote:msupepper wrote:Lightndattic wrote:The twin cannons on the lower fuselage is the one thing that comes to mind.
Yeah, that was one of mine. They also used a 2-door upper lift fan door, which is X-35 stuff. The production version will have a single aft-hinged door. My responsibility on the F-35 is with hydraulics, so that's what I first noticed.
I didn't really pay attention to the markings on the tail, and I'm curious whether the instruments were correct. I also thought the gun(s) fired longer than the capacity of the magazine, but I don't really know the capacity. How quickly would something FOD'ing the ULF cause a catastrauphic failure? It seemed to be a slower process on the movie than I would expect. Does the canopy come off during ejection? Do you think the airplane could actually maneuver under a bridge like was done in the movie?
Overall I was pretty impressed at Hollywood's attempt. The F-22 on Transformers was good, too.
The F-35 adopted the Harrier method of ejection which is lining the transparency with explosives (yeehaa!). I think the reasoning behind this is that during STOVL ops, the milliseconds waiting for the canopy to clear the ejection path are too precious.
You are sort of right. The reason is that the Harrier, Hawk, JAS-39, F/A-18 and many other modern combat aircraft are fitted with MDC in or on the canopy is to save time during ejection. It takes a finite time for the canopy jettison system to work, if it does not work you are in difficulty. Generally, explosives are more reliable than actuators etc.
With the MDC installed the canopy will shatter as the seat initiates, if you have a MB seat then the top of the box is toughened to shatter the canopy if the cord does not fire.
This becomes more important in the event of an underwater ejection where you may have to wait for the ship to clear overhead before ejecting.
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The caution/warning lights in the cockpit after the vert fan was fodded out is what struck me as being funny! I've never seen a "total fail" light! Might as well put a "you're screwed" light next to it. LoL
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Yeah, the twin lower fuselage guns and lift fan doors were stuff I noticed right off. But like msupepper, I give the producers credit to include the "F-35" in the movie. After all, they could've chose to use the Harrier (a la True Lies) again.
I'm watching...
msupepper wrote:How quickly would something FOD'ing the ULF cause a catastrauphic failure? It seemed to be a slower process on the movie than I would expect.
How fast a FODed fan would fail is very subjective.
1.What type of material was ingested?
2. How much material was ingested?
3. How much damage was done?
4. Where did the damage occur?
5. Has the damage caused a severe "out of balance" condition in the fan?
6. Is the bearing strong enough to handle the "out of balance" condition?
I'll explain a little.
1. The hardness of the FOD will change the nature of the damage. Modern fans blades are "hardened" to resist FOD. Metal will do more damage than ice. Stone will do more damage birds, etc
2. Amount of FOD is critical. One stone may damage a few blades, but will most likely be destroyed quickly after a few hits on few blades. Now suck in lots of stones and the damage would be very extensive to many blades Small birds like a sparrow will not do much damage either, but a large 10 pound buzzard will. Multiple small birds are almost as bad as a large bird, but aren't a large mass in a single concentrated spot. This may damage many blades but not be enough too break a blade off completely.
3. The number of blades damaged can affect the performance of the engine. Many damaged blades will reduce efficiency; this may not cause failure but will reduce power. If blades are broken, the amount of broken blades and amount of lost material will affect the balance of the fan. (Which is important later...) Material broken from one stage of the will travel down-stream in a "domino effect", or can even "snowball" as the "Domestic Object Debris" or DOD moves through the engine with the original FOD.
4. The size/weight of the FOD and where it strikes the blades is important. Large/hard strikes near the tip can snap blades completely off, or remove portions of the blades. Also; Relatively small nicks or tears near the root or base of a blade are more critical as the force of the spinning blade places more stress on the damage than the same type/size damage near the tip. Missing blades will cause severe imbalance, where a small chunk near a tip will not.
5. Fan rotors spin around 10,000 RPM. A few ounces or grams of material can cause a vibration; a couple pounds of missing blades or blade chunks will cause a severe unbalanced condition. This unbalance condition can cause parts within the fan or other sections of the engine to fail very quickly due to stresses transfered to them.
6. Bearings in the fan would have to accept any out of balance condition. The greater the unequal radial load (out of balance) the faster the bearing would fail. A moderate to strong vibration would not cause the bearing to fail quickly, but a severe or extreme vibration could cause the bearing to fail within seconds if not immediately. When a main bearing fails within a jet engine (or lift fan) it will cause almost immediate and complete destruction, resulting in a total loss of thrust.
Clear as mud?
Now the Fans of the F135 (it's ULF) and F119 have massive blades that are VERY resistant to FOD. Most of the above would relate to more conventional fighter fan designs like the F100 or F110 of the Viper.
But remember, everything has it's limits...
Guess I'll have to rent the movie to get a good laugh?
My favorite "jet engine scene" is in "Eraser" starring Arnold Schwarzenegger and Vanessa Williams. At one point he has to escape a flying aircraft with side mounted engines. After opening a door he realizes he'll be headed right into an engine if he exits the aircraft. To fix the situation he rips a seat from the floor and drops it out the door into the engine. WHAM-BANG!! Wicked cool!
I totally embarrassed my date when I jumped up an shouted in the middle of the theater...
Keep 'em flyin'
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That_Engine_Guy wrote:msupepper wrote:How quickly would something FOD'ing the ULF cause a catastrauphic failure? It seemed to be a slower process on the movie than I would expect.
How fast a FODed fan would fail is very subjective.
1.What type of material was ingested?
2. How much material was ingested?
3. How much damage was done?
4. Where did the damage occur?
5. Has the damage caused a severe "out of balance" condition in the fan?
6. Is the bearing strong enough to handle the "out of balance" condition?
I'll explain a little.
1. The hardness of the FOD will change the nature of the damage. Modern fans blades are "hardened" to resist FOD. Metal will do more damage than ice. Stone will do more damage birds, etc
2. Amount of FOD is critical. One stone may damage a few blades, but will most likely be destroyed quickly after a few hits on few blades. Now suck in lots of stones and the damage would be very extensive to many blades Small birds like a sparrow will not do much damage either, but a large 10 pound buzzard will. Multiple small birds are almost as bad as a large bird, but aren't a large mass in a single concentrated spot. This may damage many blades but not be enough too break a blade off completely.
3. The number of blades damaged can affect the performance of the engine. Many damaged blades will reduce efficiency; this may not cause failure but will reduce power. If blades are broken, the amount of broken blades and amount of lost material will affect the balance of the fan. (Which is important later...) Material broken from one stage of the will travel down-stream in a "domino effect", or can even "snowball" as the "Domestic Object Debris" or DOD moves through the engine with the original FOD.
4. The size/weight of the FOD and where it strikes the blades is important. Large/hard strikes near the tip can snap blades completely off, or remove portions of the blades. Also; Relatively small nicks or tears near the root or base of a blade are more critical as the force of the spinning blade places more stress on the damage than the same type/size damage near the tip. Missing blades will cause severe imbalance, where a small chunk near a tip will not.
5. Fan rotors spin around 10,000 RPM. A few ounces or grams of material can cause a vibration; a couple pounds of missing blades or blade chunks will cause a severe unbalanced condition. This unbalance condition can cause parts within the fan or other sections of the engine to fail very quickly due to stresses transfered to them.
6. Bearings in the fan would have to accept any out of balance condition. The greater the unequal radial load (out of balance) the faster the bearing would fail. A moderate to strong vibration would not cause the bearing to fail quickly, but a severe or extreme vibration could cause the bearing to fail within seconds if not immediately. When a main bearing fails within a jet engine (or lift fan) it will cause almost immediate and complete destruction, resulting in a total loss of thrust.
Clear as mud?
Now the Fans of the F135 (it's ULF) and F119 have massive blades that are VERY resistant to FOD. Most of the above would relate to more conventional fighter fan designs like the F100 or F110 of the Viper.
But remember, everything has it's limits...
Guess I'll have to rent the movie to get a good laugh?
My favorite "jet engine scene" is in "Eraser" starring Arnold Schwarzenegger and Vanessa Williams. At one point he has to escape a flying aircraft with side mounted engines. After opening a door he realizes he'll be headed right into an engine if he exits the aircraft. To fix the situation he rips a seat from the floor and drops it out the door into the engine. WHAM-BANG!! Wicked cool!
I totally embarrassed my date when I jumped up an shouted in the middle of the theater...
Keep 'em flyin'
I'll like to add that there is also the issue of whether the foreign object is merely hits the fan or whether it goes through the core. The fan can take a lot more abuse than the core. For one thing the blades are larger and more robust. The other thing is that the rotational speed of the low pressure spool which the fan runs off of is much lower. In addition, clearances are larger and any vibration resulting from imbalance is less likely to cause blade to case contact. Lastly, The if the object merely hits the fan and goes down the bypass duct only one element of the engine is damaged. If the object goes through the core, the damage is almost always cascaded though numerous compressor stages.
Of this reason, commercial high bypass turbofans incorporate designs that reject foreign objects into the fan duct before they enter the core. This usually takes the form of an S-shaped duct in the low pressure spool with a rejection vent at the inflex zone. Military fighter engines are much more vulnerable to FOD damage for the reasons that the small diameter, low bypass engines do not have the diameter to incorporate a FOD rejection feature. In addition with bypass ratios ranging from 0.2:1 to 0.75:1, between 83% and 57% of the intake flow goes through the core. In a commercial high bypass turbofan, bypass ratios are in the 4.5:1 to 11:1 range meaning that only between 18% and 8% of the flow actually goes through the core. What this means is that FODs are much more likely to enter the core of a fighter engine than a commercial turbofan.
Very true, the core of an engine is much more likely to be damaged by FOD in a fighter than a commercial, and damage there is more critical.
I was going after the "How quickly would something FOD'ing the ULF cause a catastrauphic failure? It seemed to be a slower process on the movie than I would expect. " statement...
I was going after the "How quickly would something FOD'ing the ULF cause a catastrauphic failure? It seemed to be a slower process on the movie than I would expect. " statement...
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