Any clues how the F-35 will handle in bad weather?
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So how do you think the F-35 will handle in a thunderstorm, rain with heavy down pour, snow storm, etc.
For that matter, how do the other 4th generation fighters handle in those situations when they get stuck flying in that kind of weather?
For that matter, how do the other 4th generation fighters handle in those situations when they get stuck flying in that kind of weather?
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Already we know that for the moment (I have not seen reference to this restriction being lifted) the F-35 cannot fly near thunderstorms or where lightning strikes may be experienced. The problem is being addressed perhaps even not in force today. Otherwise the F-35 has tough stealth coating that requires actual airframe damage to even begin to degrade it. You have seen reference to this already. I hope then it follows that any weather events are not a problem except for lightning at moment.
Otherwise flying in a thunderstorm deliberately is never recommended although it may have to be done for operational reasons, otherwise they are avoided where possible. Thunderstorms create enormous internal forces updrafts and downdrafts. Thunderstorms approaching an airfield create the 'microburst' phenomena which can be very confusing for unwary pilots although I would guess the F-35 is very responsive in every aspect to overcome most adverse weather events. You oughtta download my very large PDF (see the signature below my post). Just about every reasonable event for a nasal radiator is covered including weather, hypoxia, G effects and you name it. Will save you having to ask these quite basic questions. Otherwise the internet is a vast field of knowledge about the basics. Jump in.
The F-35 with JPALS will have a phenomenal ability to operate in any weather (within reason) and especially to land in adverse weather at night with extreme accuracy automatically. Lots of this and other info in the 'How to Deck Land' PDF which does not have the boring 'other information' contained in the 4.4GB PDF.
Plus we would have to guess that the F-35 is under test while flying in extreme weather is not going to be the first test point but rather near the end when more is known about the ability of the aircraft to recover from Unusual Attitudes and suchlike. Always a hazard in instrument flying conditions when in a thunderstorm for example or whatever adverse event occurs.
And I'll have to concede that the F-35 will fly very well on autopilot with the pilot monitoring the instrument descent or whatever else is required (as well as monitoring what the aircraft is doing) which for a single pilot in old jet aircraft could be quite a handful depending on circumstances in instrument flying conditions.
Otherwise flying in a thunderstorm deliberately is never recommended although it may have to be done for operational reasons, otherwise they are avoided where possible. Thunderstorms create enormous internal forces updrafts and downdrafts. Thunderstorms approaching an airfield create the 'microburst' phenomena which can be very confusing for unwary pilots although I would guess the F-35 is very responsive in every aspect to overcome most adverse weather events. You oughtta download my very large PDF (see the signature below my post). Just about every reasonable event for a nasal radiator is covered including weather, hypoxia, G effects and you name it. Will save you having to ask these quite basic questions. Otherwise the internet is a vast field of knowledge about the basics. Jump in.
The F-35 with JPALS will have a phenomenal ability to operate in any weather (within reason) and especially to land in adverse weather at night with extreme accuracy automatically. Lots of this and other info in the 'How to Deck Land' PDF which does not have the boring 'other information' contained in the 4.4GB PDF.
Plus we would have to guess that the F-35 is under test while flying in extreme weather is not going to be the first test point but rather near the end when more is known about the ability of the aircraft to recover from Unusual Attitudes and suchlike. Always a hazard in instrument flying conditions when in a thunderstorm for example or whatever adverse event occurs.
And I'll have to concede that the F-35 will fly very well on autopilot with the pilot monitoring the instrument descent or whatever else is required (as well as monitoring what the aircraft is doing) which for a single pilot in old jet aircraft could be quite a handful depending on circumstances in instrument flying conditions.
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kamenriderblade wrote:So how do you think the F-35 will handle in a thunderstorm, rain with heavy down pour, snow storm, etc.
For that matter, how do the other 4th generation fighters handle in those situations when they get stuck flying in that kind of weather?
Problem with bad weather (raindrops) is the erosion on the leading edges. The best material to deal with that is stainless steel or other hard metals. The problem for F-35 is that they probably (!) would like to have some sort of absorbant structure at the leading edge, and no known metal can do that. They will have to use some sort of transparent erosion protection, and though relatively effective, not quite as good as steel.
I think that the "problem" will be manageable.
Lightnings, rain and snow will be (as much problem as) on any other airplane, the conventional solutions will work on F-35 as well.
But as spazsinbad says, if you can avoid bad weather, it is allways a good idea to do so.
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No announcement yet of the variants being tested at the climate lab at Eglin.
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Vaguely I recall non-flying F-35 test airframes early on being tested in a climate lab somewhere already. Not so - according to this article...
F-35 Flight Test Perspectives by Eric Hehs 15 Sep 2008 Eric Hehs is the editor of Code One.
http://www.codeonemagazine.com/article.html?item_id=29
"...Stefano Filoni joined the F-35 program in 2004 to develop test plans for F-35 climatic testing, which is scheduled for the climatic test laboratory at Eglin AFB, Florida, in 2010. He also writes test plans for utility and subsystem testing for the F-35B. Before joining the F-35 program, Filoni worked for Alenia Aeronautica in Italy as a flight test engineer on the C-27J Spartan program. He was responsible for performance and handling quali-ties for the Spartan. He was also involved in hot- and cold-soak testing for that two-engine airlifter that makes use of the engines and avionics developed for the C-130J Super Hercules. Filoni graduated from the University of Naples Federico II in 1999. He came to the United States in 2004 to work on the F-35 program.
The climatic test plans I am creating will test the F-35B at high and low temperatures. However, before the program actually takes an aircraft to Eglin for these tests, we must complete a lot of work. For example, we have to build a tie-down and platform for the tests because none currently exist for this new airplane. We also have to design the ductwork that removes the exhaust from the facility. Because we will be testing a STOVL aircraft, the downward thrust has to be redirected out of the facility as well.
For the actual climatic testing on the F-35, we will use a mission systems aircraft—that is, a test aircraft outfitted with all the avionics and systems found on an operational aircraft. High-temperature and low-temperature test-ing involves multiple test runs. We will simulate entire missions during these tests. We start the engine, retract the landing gear, fire the gun, release weapons, extend the landing gear, and perform everything in between.
For high-temperature tests, our baseline temperature is 59 degrees Fahrenheit. We perform the same test at 113 degrees F and finally at 120 degrees F. The cold tests are more involved. We perform the first cold test at minus 15 degrees F. We simulate an alert launch at this temperature. A pilot climbs in the jet, starts the engine, and performs a simulated takeoff—all within five minutes from the start of the test. Then we perform a self-start test at minus 25 degrees F. Self-start means starting the aircraft without help from an outside source.
The last cold test is at minus 40 degrees F. We will cold soak the aircraft to minus 65 degrees F for this test.
Other test conditions to be covered during the climatic lab trials include snow, high humidity, rain, freezing rain, and icing. I am looking forward to conducting an actual flight test. The F-35B has three test conductors now, but we are training more to prepare for the additional test aircraft...."
F-35 Flight Test Perspectives by Eric Hehs 15 Sep 2008 Eric Hehs is the editor of Code One.
http://www.codeonemagazine.com/article.html?item_id=29
"...Stefano Filoni joined the F-35 program in 2004 to develop test plans for F-35 climatic testing, which is scheduled for the climatic test laboratory at Eglin AFB, Florida, in 2010. He also writes test plans for utility and subsystem testing for the F-35B. Before joining the F-35 program, Filoni worked for Alenia Aeronautica in Italy as a flight test engineer on the C-27J Spartan program. He was responsible for performance and handling quali-ties for the Spartan. He was also involved in hot- and cold-soak testing for that two-engine airlifter that makes use of the engines and avionics developed for the C-130J Super Hercules. Filoni graduated from the University of Naples Federico II in 1999. He came to the United States in 2004 to work on the F-35 program.
The climatic test plans I am creating will test the F-35B at high and low temperatures. However, before the program actually takes an aircraft to Eglin for these tests, we must complete a lot of work. For example, we have to build a tie-down and platform for the tests because none currently exist for this new airplane. We also have to design the ductwork that removes the exhaust from the facility. Because we will be testing a STOVL aircraft, the downward thrust has to be redirected out of the facility as well.
For the actual climatic testing on the F-35, we will use a mission systems aircraft—that is, a test aircraft outfitted with all the avionics and systems found on an operational aircraft. High-temperature and low-temperature test-ing involves multiple test runs. We will simulate entire missions during these tests. We start the engine, retract the landing gear, fire the gun, release weapons, extend the landing gear, and perform everything in between.
For high-temperature tests, our baseline temperature is 59 degrees Fahrenheit. We perform the same test at 113 degrees F and finally at 120 degrees F. The cold tests are more involved. We perform the first cold test at minus 15 degrees F. We simulate an alert launch at this temperature. A pilot climbs in the jet, starts the engine, and performs a simulated takeoff—all within five minutes from the start of the test. Then we perform a self-start test at minus 25 degrees F. Self-start means starting the aircraft without help from an outside source.
The last cold test is at minus 40 degrees F. We will cold soak the aircraft to minus 65 degrees F for this test.
Other test conditions to be covered during the climatic lab trials include snow, high humidity, rain, freezing rain, and icing. I am looking forward to conducting an actual flight test. The F-35B has three test conductors now, but we are training more to prepare for the additional test aircraft...."
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This is what I was probably vaguely remembering reading before it was known that the F-35B was going to melt decks and shite.
BAE Systems Advanced Noise and Vibration Testing Facilities at Warton and Brough
http://www.bksv.com.au/doc/ba0780.pdf (600Kb)
Acoustic Fatigue Test Facility – Warton
The Acoustic Fatigue Facility at Warton in 1999 is one of only a few such facilities worldwide and has been developed in line with identified future test requirements relating to a new generation of vertical take off and landing aircraft which must operate under extremes of noise and heat, and possible research and development testing to support the design of future advanced airframe structures....
Thermo-Acoustic Facility – Joint Strike Fighter
Fig. 10 1/15th scale model of the JSF STOVL variant
The Thermo-Acoustic Facility (TAF) at Brough is currently being used to simulate the ground environment on and around the short-take off/vertical landing (STOVL) and carrier variants (CV) of the Joint Strike Fighter F35 using a 1/l5th scale model. This is the only facility in the world designed specifically to measure the thermal and acoustic environment around vertical take off aircraft at model scale.
Andy Russell (another Andy) is Technical Specialist Thermo-Acoustic Testing and responsible for the TAF facility. Andy explains, “When a STOVL aircraft is hovering above the ground, the weight of the aircraft is supported solely by columns of gas generated by the aircraft’s engine(s). These columns of gas spread out in all directions when they hit the ground - jet outwash. A further effect is where a fountain of gas comes back up from the ground hitting the underside of the aircraft. The TAF measures the airflow, temperatures and noise on and around the aircraft, both from the jet outwash on the ground and the upwash onto the aircraft underside”.
The facility operates by burning a mixture of air and hydrogen in gas turbine combustion chambers, piping the gasses into accurately modelled jet nozzles which recreate the actual engine exhaust gas temperatures and pressures, which are essential in recreating the acoustic environment. The model fuselage and wing are manufactured from high-temperature steel which has been profiled using CNC machining centres. The jet nozzles have been produced using investment casting direct from the computer model.
Fig. 11
The Thermo-acoustic test facility at BAE Systems’ Brough site. A computer controlled table is used to simulate the ground, and can be moved to various heights away from the aircraft. The facility has recently been enhanced to allow it to take simulated aircraft carrier deck measurements for the JSF carrier variant
Andy continues, “The model is mounted in the centre of the semi anechoic facility which is lined with sound deadening foam wedges above a computer controlled table. This simulates the ground and is moved to various heights away from the aircraft. Probes around the edge of the table sweep around during the test to measure the outwash air speed, temperature and sound levels”.
The underside of the aircraft model is instrumented with 48 miniature pressure transducers, each with custom-made water cooling jackets necessary for the transducers to survive the environment, and 48 clusters of thermal instrumentation measuring air temperature, air pressure and the transfer of heat into the aircraft. Data is gathered 200 000 times per second for each of the pressure transducers and a 100 times per second for the thermal data.
For each pressure transducer, a Brüel&Kjær High Pressure Microphone Calibrator Type 4221 is used together with a custom made adapter to provide the traceability back to national standards by back-to-back calibration against a Type 4138 reference microphone.
Andy adds, “Following the test, the data is post-processed to determine the conditions underneath the real aircraft and to predict the contours around the aircraft where ground crew can safely work. The effect upon the aircraft structure resulting from exposure to these high noise levels and operating temperatures is evaluated in the Acoustic Fatigue Facility and provides structural qualification evidence”. Ian concludes, “All the microphones, accelerometers, calibrators and signal conditioning used in our test facilities at Brough are supplied by Brüel&Kjær. We have used their products for many years and regard them as the reference standard”.
Bird Strike Test Facility
An unusual but vitally important facility at Brough tests the effects of bird strikes on airframe components such as the cockpit canopy or radomes. A large bird striking an aircraft at subsonic speeds of up to 500 knots creates a huge shock and is potentially hazardous. To simulate this, a laser guided pneumatic ‘cannon’ has been developed which propels a dead chicken at a range of 5 to 10 metres on to the test object. The structural effects of the impact (if any) are clearly visible. In additions accelerometers are used to measure the acceleration of the high speed collision."
BAE Systems Advanced Noise and Vibration Testing Facilities at Warton and Brough
http://www.bksv.com.au/doc/ba0780.pdf (600Kb)
Acoustic Fatigue Test Facility – Warton
The Acoustic Fatigue Facility at Warton in 1999 is one of only a few such facilities worldwide and has been developed in line with identified future test requirements relating to a new generation of vertical take off and landing aircraft which must operate under extremes of noise and heat, and possible research and development testing to support the design of future advanced airframe structures....
Thermo-Acoustic Facility – Joint Strike Fighter
Fig. 10 1/15th scale model of the JSF STOVL variant
The Thermo-Acoustic Facility (TAF) at Brough is currently being used to simulate the ground environment on and around the short-take off/vertical landing (STOVL) and carrier variants (CV) of the Joint Strike Fighter F35 using a 1/l5th scale model. This is the only facility in the world designed specifically to measure the thermal and acoustic environment around vertical take off aircraft at model scale.
Andy Russell (another Andy) is Technical Specialist Thermo-Acoustic Testing and responsible for the TAF facility. Andy explains, “When a STOVL aircraft is hovering above the ground, the weight of the aircraft is supported solely by columns of gas generated by the aircraft’s engine(s). These columns of gas spread out in all directions when they hit the ground - jet outwash. A further effect is where a fountain of gas comes back up from the ground hitting the underside of the aircraft. The TAF measures the airflow, temperatures and noise on and around the aircraft, both from the jet outwash on the ground and the upwash onto the aircraft underside”.
The facility operates by burning a mixture of air and hydrogen in gas turbine combustion chambers, piping the gasses into accurately modelled jet nozzles which recreate the actual engine exhaust gas temperatures and pressures, which are essential in recreating the acoustic environment. The model fuselage and wing are manufactured from high-temperature steel which has been profiled using CNC machining centres. The jet nozzles have been produced using investment casting direct from the computer model.
Fig. 11
The Thermo-acoustic test facility at BAE Systems’ Brough site. A computer controlled table is used to simulate the ground, and can be moved to various heights away from the aircraft. The facility has recently been enhanced to allow it to take simulated aircraft carrier deck measurements for the JSF carrier variant
Andy continues, “The model is mounted in the centre of the semi anechoic facility which is lined with sound deadening foam wedges above a computer controlled table. This simulates the ground and is moved to various heights away from the aircraft. Probes around the edge of the table sweep around during the test to measure the outwash air speed, temperature and sound levels”.
The underside of the aircraft model is instrumented with 48 miniature pressure transducers, each with custom-made water cooling jackets necessary for the transducers to survive the environment, and 48 clusters of thermal instrumentation measuring air temperature, air pressure and the transfer of heat into the aircraft. Data is gathered 200 000 times per second for each of the pressure transducers and a 100 times per second for the thermal data.
For each pressure transducer, a Brüel&Kjær High Pressure Microphone Calibrator Type 4221 is used together with a custom made adapter to provide the traceability back to national standards by back-to-back calibration against a Type 4138 reference microphone.
Andy adds, “Following the test, the data is post-processed to determine the conditions underneath the real aircraft and to predict the contours around the aircraft where ground crew can safely work. The effect upon the aircraft structure resulting from exposure to these high noise levels and operating temperatures is evaluated in the Acoustic Fatigue Facility and provides structural qualification evidence”. Ian concludes, “All the microphones, accelerometers, calibrators and signal conditioning used in our test facilities at Brough are supplied by Brüel&Kjær. We have used their products for many years and regard them as the reference standard”.
Bird Strike Test Facility
An unusual but vitally important facility at Brough tests the effects of bird strikes on airframe components such as the cockpit canopy or radomes. A large bird striking an aircraft at subsonic speeds of up to 500 knots creates a huge shock and is potentially hazardous. To simulate this, a laser guided pneumatic ‘cannon’ has been developed which propels a dead chicken at a range of 5 to 10 metres on to the test object. The structural effects of the impact (if any) are clearly visible. In additions accelerometers are used to measure the acceleration of the high speed collision."
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Perhaps useful?
Resins for the Hot Zone, Part II: BMIs, CEs, benzoxazines and phthalonitriles Sep 2009
"...The F-35, now in development in three variants (conventional take off/landing or CTOL, short take off/vertical landing or STOVL, and carrier configuration), also uses CYCOM 5250-4 BMI in carbon fiber prepregs. To date, all carbon fiber/BMI components on the F-35 are autoclave-cured. While some smaller parts are hand layed, larger parts, such as the upper and lower wingskins and engine nacelle skins, are fabricated via automated fiber placement (AFP). Lockheed reports that after some initial degradation in lay-down rates due to low resin tack and slit tape cleanliness, the BMI fiber placement process now shows significant labor reduction. AFP reduces the potential for errors in complex ply definitions through repeatable NC programming, and it improves fiber orientation by eliminating the tendency for hand-layed fiber to follow the natural path on part contours. AFP also maintains the F-35 concept of ‘digital thread’ by linking the engineering model directly to automated fabrication.
Depending upon the variant, 20 to 30 percent of the F-35 airframe structural weight is composite, with well over 50 percent of that weight in carbon fiber/BMI. This material system is considered extremely important in the F-35 team’s effort to replace metal and meet air vehicle weight requirements. The extended timeline of the F-35’s 10-year System Design and Development (SDD) phase has enabled evaluation of new materials and process advancements, such as those developed in Small Business Innovation Research (SBIR) programs. A recent SBIR example is Quickstep Technologies Pty. Ltd.’s (North Coogee, Western Australia) work with Vector Composites (Dayton, Ohio) to develop an out-of-autoclave cure cycle for carbon fiber/BMI components. “Considering the potential high rate of production planned for this aircraft,” says Dale Brosius, Quickstep’s U.S.-based COO, ”a process that can shorten overall cure cycle and get it out of the autoclave could greatly reduce recurring manufacturing costs and overall tooling investment.”..."
Picture Caption:http://d2n4wb9orp1vta.cloudfront.net/resources/images/cdn/cms/0909hpc_HPresins5.jpg
"Automatically fiber placed carbon fiber/epoxy and BMI in composite components onboard the F-35 comprise up to 30 percent of the new multirole fighter’s airframe. Source: Lockheed Martin"
Resins for the Hot Zone, Part II: BMIs, CEs, benzoxazines and phthalonitriles Sep 2009
"...The F-35, now in development in three variants (conventional take off/landing or CTOL, short take off/vertical landing or STOVL, and carrier configuration), also uses CYCOM 5250-4 BMI in carbon fiber prepregs. To date, all carbon fiber/BMI components on the F-35 are autoclave-cured. While some smaller parts are hand layed, larger parts, such as the upper and lower wingskins and engine nacelle skins, are fabricated via automated fiber placement (AFP). Lockheed reports that after some initial degradation in lay-down rates due to low resin tack and slit tape cleanliness, the BMI fiber placement process now shows significant labor reduction. AFP reduces the potential for errors in complex ply definitions through repeatable NC programming, and it improves fiber orientation by eliminating the tendency for hand-layed fiber to follow the natural path on part contours. AFP also maintains the F-35 concept of ‘digital thread’ by linking the engineering model directly to automated fabrication.
Depending upon the variant, 20 to 30 percent of the F-35 airframe structural weight is composite, with well over 50 percent of that weight in carbon fiber/BMI. This material system is considered extremely important in the F-35 team’s effort to replace metal and meet air vehicle weight requirements. The extended timeline of the F-35’s 10-year System Design and Development (SDD) phase has enabled evaluation of new materials and process advancements, such as those developed in Small Business Innovation Research (SBIR) programs. A recent SBIR example is Quickstep Technologies Pty. Ltd.’s (North Coogee, Western Australia) work with Vector Composites (Dayton, Ohio) to develop an out-of-autoclave cure cycle for carbon fiber/BMI components. “Considering the potential high rate of production planned for this aircraft,” says Dale Brosius, Quickstep’s U.S.-based COO, ”a process that can shorten overall cure cycle and get it out of the autoclave could greatly reduce recurring manufacturing costs and overall tooling investment.”..."
Picture Caption:http://d2n4wb9orp1vta.cloudfront.net/resources/images/cdn/cms/0909hpc_HPresins5.jpg
"Automatically fiber placed carbon fiber/epoxy and BMI in composite components onboard the F-35 comprise up to 30 percent of the new multirole fighter’s airframe. Source: Lockheed Martin"
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Will guess the key test will be how the clutch assembly handles the cold soak and start-up at -40 F and or C. Lubricants get viscous fast at those temperatures.
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Salute!
I have not seen the F-35 at the climatic hangar last two years, but it could have sneaked in here.
From personal experience, only ablation I ever had was in a CB with hail. It eroded the "fiberglass" stuff on leading edges of antannas and such.
As far as lightning goes, my Viper wingman had a lightning strike right at the forward edge of the canopy. All the FLCS lights came on. He reset and pressed on. Gotta realize that since the 70's that most of our gear is extremely hardened for EMP. So I would not worry as much about the electrons as I would loss of the LO until I got home and they could repair.
Gums sends...
I have not seen the F-35 at the climatic hangar last two years, but it could have sneaked in here.
From personal experience, only ablation I ever had was in a CB with hail. It eroded the "fiberglass" stuff on leading edges of antannas and such.
As far as lightning goes, my Viper wingman had a lightning strike right at the forward edge of the canopy. All the FLCS lights came on. He reset and pressed on. Gotta realize that since the 70's that most of our gear is extremely hardened for EMP. So I would not worry as much about the electrons as I would loss of the LO until I got home and they could repair.
Gums sends...
Gums
Viper pilot '79
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The F-35 will handle rough weather just fine. The technoloy to deal with lightning strikes in composite aircratft is well developed as the Boeing 787 can attest to. What I am curious about is how the F-35 coatings will handle Canadian Snow and Frost.?
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Perhaps as suggested this lightning protection info is 'old hat' but mentioned here in Nov 2011....
F-35 Joint strike Fighter Concurrency Quick Look Review 29 Nov 2011
http://s3.documentcloud.org/documents/2 ... report.pdf (18Mb)
Lightning Protection: The F-35 employs an active lightning protection system, which presents challenges to certification compared to a more conventional passive system. A 25 nm lightning restriction and dive rate limitations are in place for all aircraft until partial certification is completed at the end of 2012, with full certification expected in the 2014-2016 timeframe." PAGE 8
________________________
"Lightning Protection: The F-35 employs an active lightning protection system, which presents challenges to certification compared to a more conventional passive system. [b]The F-35 outer surfaces are safety compliant, but there are seven subsystems not yet meeting safety qualification standards..... In addition, there is no fuel tank inerting (and therefore no lightning protection) when aircraft are parked. Improved inerting is being addressed via a two-phase design effort. The first phase has completed a Preliminary Design Review and will focus on OBIGGS changes. The second phase will emphasies fuel vent valve redesign in order to allow full dive rate capability (however, this is not currently scheduled before 2014). The contractor is also investigating design options for lightning protection while aircraft are parked, such as pre-charging fuel tanks with nitrogen using an auxiliary cart and adding a dedicated service port to the aircraft.
In the interim, a 25 nm lightning restriction and dive rate limitations are in place for all aircraft until partial certification is completed at the end of 2012, with full certification expected in the 2014-2016 timeframe. As Eglin AFB is located in a significant lightning environment, the current 25 nm restriction could lead to cancelling an estimated 25-50 percent of planned training events due to typical proximity and frequency of thunderstorm activity.
Conclusion: Moderate Concurrency Risk - full certification is not expected until 2014-2016" PAGE 18
F-35 Joint strike Fighter Concurrency Quick Look Review 29 Nov 2011
http://s3.documentcloud.org/documents/2 ... report.pdf (18Mb)
Lightning Protection: The F-35 employs an active lightning protection system, which presents challenges to certification compared to a more conventional passive system. A 25 nm lightning restriction and dive rate limitations are in place for all aircraft until partial certification is completed at the end of 2012, with full certification expected in the 2014-2016 timeframe." PAGE 8
________________________
"Lightning Protection: The F-35 employs an active lightning protection system, which presents challenges to certification compared to a more conventional passive system. [b]The F-35 outer surfaces are safety compliant, but there are seven subsystems not yet meeting safety qualification standards..... In addition, there is no fuel tank inerting (and therefore no lightning protection) when aircraft are parked. Improved inerting is being addressed via a two-phase design effort. The first phase has completed a Preliminary Design Review and will focus on OBIGGS changes. The second phase will emphasies fuel vent valve redesign in order to allow full dive rate capability (however, this is not currently scheduled before 2014). The contractor is also investigating design options for lightning protection while aircraft are parked, such as pre-charging fuel tanks with nitrogen using an auxiliary cart and adding a dedicated service port to the aircraft.
In the interim, a 25 nm lightning restriction and dive rate limitations are in place for all aircraft until partial certification is completed at the end of 2012, with full certification expected in the 2014-2016 timeframe. As Eglin AFB is located in a significant lightning environment, the current 25 nm restriction could lead to cancelling an estimated 25-50 percent of planned training events due to typical proximity and frequency of thunderstorm activity.
Conclusion: Moderate Concurrency Risk - full certification is not expected until 2014-2016" PAGE 18
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Gums wrote: As far as lightning goes, my Viper wingman had a lightning strike right at the forward edge of the canopy. All the FLCS lights came on. He reset and pressed on. Gotta realize that since the 70's that most of our gear is extremely hardened for EMP. So I would not worry as much about the electrons as I would loss of the LO until I got home and they could repair.
The lightning vulnerability of the Viper isn't the Viper itself, it's the external fuel tanks. Although some improvements in tank construction were made after some Viper losses from lightning-caused external tank explosions, I don't think the improvements completely eliminated the vulnerability. Hopefully the Viper's history has been considered in the design for the F-35 tanks.
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alloycowboy wrote:The F-35 will handle rough weather just fine. The technoloy to deal with lightning strikes in composite aircratft is well developed as the Boeing 787 can attest to. What I am curious about is how the F-35 coatings will handle Canadian Snow and Frost.?
I believe snow and frost won't be a problem, at least not more than it is to other aircrafts....
But on the lightning subject there is one big difference between the 787 and an airplane that is supposed to reduce radar energy return. On the 787 the lightning protection is on top of the surface. (Historically it is a thin net made of copper or stainless IIRC, I don't remember on top of my head what the 787 have done.) If you on the other hand shall absorb radar energy in a material you can not have a conducting net on top.....
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Last edited by linkomart on 14 Dec 2012, 20:34, edited 1 time in total.
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spazsinbad wrote:Bird Strike Test Facility
An unusual but vitally important facility at Brough tests the effects of bird strikes on airframe components such as the cockpit canopy or radomes. A large bird striking an aircraft at subsonic speeds of up to 500 knots creates a huge shock and is potentially hazardous. To simulate this, a laser guided pneumatic ‘cannon’ has been developed which propels a dead chicken at a range of 5 to 10 metres on to the test object. The structural effects of the impact (if any) are clearly visible. In additions accelerometers are used to measure the acceleration of the high speed collision."
"Laser guided"? IIRC the damm chicken have the ballistics of...well ... a chicken, and the hit point where hard to predict. Guess It's ok, because in real life you can not predict where the bird hits either....
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