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The F-35 thread, Mk II

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The F-35 thread, Mk II

Old 28th Jul 2023, 23:27
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Originally Posted by LowObservable
On the bright side, first confirmed A2A kill for the F-35!

Note that the F-35 sheds very tight, intense and persistent vortices from the wingtips. One of these seems to have blanketed the air data sensors (probe+flush) on the trailing jet, and consequent wildly erratic readings sent the FCS into full GIGO mode.
You don't post as much now, since getting your job with a prime. That nondisclosure agreement is working well. Though it's good to see you haven't lost your skill in misrepresenting the truth. The wake separation from 3,000 to 9,000ft was a base order for all aircraft. It was because of the weather conditions. Normal days are also the same 3,000ft for all aircraft.

Last edited by golder; 29th Jul 2023 at 05:41.
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Old 29th Jul 2023, 02:16
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From the USAF Mishap Report: “e. Understanding Wake Turbulence - Every aircraft generates wake turbulence while in flight. Wake turbulence is a function of an aircraft producing lift, resulting in the formation of two counter-rotating vortices trailing behind the aircraft. Wake turbulence from an aircraft can affect other aircraft due to the strength, duration, and direction of the vortices. Pilots should always be aware of the possibility of a wake turbulence encounter when flying through the wake of another aircraft and adjust the flight path accordingly.

Wake turbulence procedures at Hill AFB are intended to reduce the likelihood of following aircraft from entering wake turbulence vortices with the primary danger being an unexpected rolling motion close to the ground due to flight within the vortex, not because of an impact to the air data system of the F-35. Most F-35 pilots interviewed for this investigation and the accident investigation board’s F-35A Pilot Member, regularly experience wake turbulence while flying the aircraft. The F-35 has over 600,000 flight hours and this is the first known occurrence of wake turbulence having a catastrophic impact on the Air Data System.” https://www.afjag.af.mil/Portals/77/...B%20Report.pdf (3.2Mb)


Last edited by SpazSinbad; 29th Jul 2023 at 02:59. Reason: text+
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Old 29th Jul 2023, 20:17
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Originally Posted by golder
You don't post as much now, since getting your job with a prime. That nondisclosure agreement is working well. Though it's good to see you haven't lost your skill in misrepresenting the truth. The wake separation from 3,000 to 9,000ft was a base order for all aircraft. It was because of the weather conditions. Normal days are also the same 3,000ft for all aircraft.
And you have not lost your skill at.... hard to say, really.

Seriously, has anyone heard of wake vortices fubaring the FCS in any other case? Can't think of any, but I'm not omniscient.
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Old 29th Jul 2023, 23:26
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I am reminded of the 737 Max - a single data source with no redundancy.

would the same happen if an6 other source caused the same problem with the input?
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Old 29th Jul 2023, 23:43
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Then you've not looked very hard. Saab Gripen would be one. There's at least one other. I would hope that, given the specific air-data probes that the Rafale uses*, it's designers have taken note of that particular device's vulnerabilities and designed their FCS accordingly.

* to be fair, we're talking about something a couple of decades old now so probably replaced since

Originally Posted by LowObservable
And you have not lost your skill at.... hard to say, really.

Seriously, has anyone heard of wake vortices fubaring the FCS in any other case? Can't think of any, but I'm not omniscient.
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Old 30th Jul 2023, 04:27
  #606 (permalink)  
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Kalman, anyone..?

re the image of the vortex wake, it is misleading in the response of the following aircraft from the tip vortex and sheet rollup:
If the right wing of the following aircraft enters the wake structure, the roll is in the opposite sense, it's an upwash region.
If the aircraft enters obliquely, pitch will be affected, initially a pitch down...

The F-35 will shed pretty energetic tip vortices with full flap, (no surprise there low aspect, high CL), but the following aircraft has oodles of control authority, if the confusers are allowing the driver to apply an input. The P/S systems going to the ADC's if based on static sensors are very sensitive to perturbation, statics always are. In reviewing wake encounter data for RPT aircraft, the static data gives a pretty clear indication of the entry and exit of the conditions, even where the plane plows happily along. Where the static system feeds to the confuser and that has authority to outvote the driver, then stuff happens.[1] How important the static system is was shown with the B2 Spirit takeoff out of Andersen, Guam a number of years ago. If fort fumble expects the drivers to do 9,000' trail, then they need to do that standard, not just when it might be turbulent. For a 4-ship recovery, that should be fun to manage... 27,000' between lead and #4 in the pattern, ~4.5nm, 1.5nm per break interval, not a 3-sec break. Pairs recovery might work better. A figure of "9000' " is arbitrary. vortices can exhibit buoyancy, interaction between the pairs, and generally are a pain to track. They will initially be above the wing plane near the wing TE, but then descent below the plane of the wing, and slowly sink over time, eventually they go to a vortex instability where they will precess with or without the interaction with the other vortex filament [2], unless the local environment has lots of shear in which case they will go to a vortex burst. Being slightly above the leading aircraft is beneficial, at all times.

[1] I'm not an F-35 background, but have done a number of investigations into wake events on airline aircraft, and have some time on FBW systems (>10K, 5 FBW types)
[2] VCI, Vortex Crow Instability, see: Crow, S. C. (1970). "Stability theory for a pair of trailing vortices". AIAA Journal.8 (12): 2172–2179.





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Old 30th Jul 2023, 12:02
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Originally Posted by NoHoverstop
Then you've not looked very hard. Saab Gripen would be one. There's at least one other. I would hope that, given the specific air-data probes that the Rafale uses*, it's designers have taken note of that particular device's vulnerabilities and designed their FCS accordingly.

* to be fair, we're talking about something a couple of decades old now so probably replaced since
Thanks. I didn't know about the 1999 accident. Wiki says that there was a S/W fix, but the source on that has 404'd.

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Old 30th Jul 2023, 12:04
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Originally Posted by fdr
Kalman, anyone..?

re the image of the vortex wake, it is misleading in the response of the following aircraft from the tip vortex and sheet rollup:
If the right wing of the following aircraft enters the wake structure, the roll is in the opposite sense, it's an upwash region.
If the aircraft enters obliquely, pitch will be affected, initially a pitch down...

The F-35 will shed pretty energetic tip vortices with full flap, (no surprise there low aspect, high CL), but the following aircraft has oodles of control authority, if the confusers are allowing the driver to apply an input. The P/S systems going to the ADC's if based on static sensors are very sensitive to perturbation, statics always are. In reviewing wake encounter data for RPT aircraft, the static data gives a pretty clear indication of the entry and exit of the conditions, even where the plane plows happily along. Where the static system feeds to the confuser and that has authority to outvote the driver, then stuff happens.[1] How important the static system is was shown with the B2 Spirit takeoff out of Andersen, Guam a number of years ago. If fort fumble expects the drivers to do 9,000' trail, then they need to do that standard, not just when it might be turbulent. For a 4-ship recovery, that should be fun to manage... 27,000' between lead and #4 in the pattern, ~4.5nm, 1.5nm per break interval, not a 3-sec break. Pairs recovery might work better. A figure of "9000' " is arbitrary. vortices can exhibit buoyancy, interaction between the pairs, and generally are a pain to track. They will initially be above the wing plane near the wing TE, but then descent below the plane of the wing, and slowly sink over time, eventually they go to a vortex instability where they will precess with or without the interaction with the other vortex filament [2], unless the local environment has lots of shear in which case they will go to a vortex burst. Being slightly above the leading aircraft is beneficial, at all times.

[1] I'm not an F-35 background, but have done a number of investigations into wake events on airline aircraft, and have some time on FBW systems (>10K, 5 FBW types)
[2] VCI, Vortex Crow Instability, see: Crow, S. C. (1970). "Stability theory for a pair of trailing vortices". AIAA Journal.8 (12): 2172–2179.
Speculation, but would tip vortices on most fighters get somewhat suppressed by pylons inhibiting spanwise flow?
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Old 1st Aug 2023, 21:25
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Belgium delays

Looks like the first pair of F-35A destined for Belgium Air Component are delayed

https://theaviationist.com/2023/08/0...-f-35-delayed/

They meant to be handed over to them at Luke AFB for FTU but theres couple of issues to be addressed....as stated...

cheers
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Old 1st Aug 2023, 22:42
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Originally Posted by LowObservable
Speculation, but would tip vortices on most fighters get somewhat suppressed by pylons inhibiting spanwise flow?
depends.


pylons mounted well aft of the LE won't act as a vortilon, but some that are closer to the LE will. Stores that extend forward of the wing LE will at various AOA start to generate vortex filaments that may rise above the wing and that can alter span wise flow, which will suppress the tip vortex. The vortex sheet rollup off the span of the wing TE will still roll up eventually being mostly drawn into the tip vortex filament.

Vortilons & external stores increase RCS almost always, but, flow modifiers can be employed that do not alter RCS appreciably.
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Old 3rd Aug 2023, 23:42
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https://www.thedrive.com/the-war-zon...-coast-highway

F-35B Just Touched Down On The Old Pacific Coast Highway

The Marines just landed an F-35B Joint Strike Fighter on an old 50-foot-wide highway in Southern California, refueled and rearmed, and took back off again. At this same improvised forward arming and refueling point, a Marine MV-22 Osprey tilt-rotor passed over a torpedo to a waiting Navy MH-60R Seahawk helicopter. This was a glimpse of what is to come for future Marine operations in the Pacific, and The War Zone was there to watch all of it unfold.

This is a preview of a very in-depth, first-person series of reports that are coming soon as part of our upcoming VMX-1 week where we will examine firsthand how this cutting-edge Marine Aviation unit is paving the way for winning a future fight in the Pacific.






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Old 26th Aug 2023, 08:42
  #612 (permalink)  
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In May 2022, Lockheed and Northrop figures told defence committee that UK MoD had no yet firmed up plans for F-35s beyond the 48 in Tranche 1 (over 30 of which are in use, with deliveries ending in 2025; production lot 17). That was not unexpected, though, it was still early days…..

https://threadreaderapp.com/thread/1...473983476.html
​​​​​​​
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Old 26th Aug 2023, 09:31
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it's a real discgrace
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Old 26th Aug 2023, 09:54
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But wasn’t UK share of the work based on the procurement of the original number? 140 was it?
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Old 30th Aug 2023, 10:09
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F-35 related. Not sure if it needs its own thread….

https://www.theguardian.com/world/20...uclear-weapons

Airbase project could pave way for UK to host US nuclear weapons

The US air force has secured $50m (£39m) funding next year for a project that could pave the way for American nuclear weapons to return to British soil for the first time in more than 15 years.

In justifying the expenditure on a 144-bed dormitory at RAF Lakenheath in Suffolk, the USAF told Congress the building was intended to “house the increase in enlisted personnel as the result of the potential surety mission”, which is jargon typically used by the Pentagon to refer to handling of nuclear weapons, according to experts.

Construction of the dormitory is due to begin in June 2024 and last until February 2026, and is the latest in a series of signs that preparations are under way for the possible return of US nuclear weapons to UK territory.

Matt Korda, of the Federation of American Scientists (FAS), who first reported on the budget request, said: “The mention of the arrival of the potential surety mission caught my eye as that is a buzzword, a term commonly used in the defence department and the nuclear weapons complex to refer to the positive control of nuclear weapons in a safe and secure way.”

The FAS previously reported that in the 2023 defence budget, the UK was added to the list of countries where infrastructure investment is under way on “special weapons” storage sites in Europe, alongside Belgium, Germany, Italy, the Netherlands and Turkey.

The FAS estimates there are about 100 B61 gravity bombs in storage in those five countries. They were withdrawn from the UK in 2007, but the storage facilities for the bombs were mothballed rather than dismantled.…..

The B61 bombs were once considered obsolete by the US military, a relic of the cold war. But instead of being retired, they have been upgraded to extend their life and improve their accuracy.

The new version, the B61-12, is expected to arrive in Europe this year. The new F-35A Lightning II fighters have been given certification to be armed with the modernised bombs, and the 495th Fighter Squadron, stationed at RAF Lakenheath, is due to become the first unit in Europe to receive the nuclear-capable planes…..

It is not clear from the budget documents whether the UK is intended to become a permanent base for US nuclear weapons, or a contingency base in the event of a crisis.

Another possibility is that when old versions of the B61 are withdrawn from Incirlik airbase in Turkey, they will not be replaced by B61-12s, because of longstanding concerns over the base’s proximity to the Syrian border and internal Turkish security after the attempted coup of 2016. In that case, the new bombs could be stationed in Lakenheath instead.
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Old 7th Sep 2023, 03:33
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Originally Posted by SpazSinbad
From the USAF Mishap Report: “e. Understanding Wake Turbulence - Every aircraft generates wake turbulence while in flight. Wake turbulence is a function of an aircraft producing lift, resulting in the formation of two counter-rotating vortices trailing behind the aircraft. Wake turbulence from an aircraft can affect other aircraft due to the strength, duration, and direction of the vortices. Pilots should always be aware of the possibility of a wake turbulence encounter when flying through the wake of another aircraft and adjust the flight path accordingly.

Wake turbulence procedures at Hill AFB are intended to reduce the likelihood of following aircraft from entering wake turbulence vortices with the primary danger being an unexpected rolling motion close to the ground due to flight within the vortex, not because of an impact to the air data system of the F-35. Most F-35 pilots interviewed for this investigation and the accident investigation board’s F-35A Pilot Member, regularly experience wake turbulence while flying the aircraft. The F-35 has over 600,000 flight hours and this is the first known occurrence of wake turbulence having a catastrophic impact on the Air Data System.” https://www.afjag.af.mil/Portals/77/...B%20Report.pdf (3.2Mb)

A good example of vortex
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Old 22nd Sep 2023, 15:37
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F-35A lands on a highway/motorway in Norway.
Lockheed Martin F-35A fighter jets land on motorway | Reuters

I wonder who did the FOD walkdown?
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Old 22nd Sep 2023, 23:05
  #618 (permalink)  
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This GAO report makes clear that F-35 sustainment is under the absolute control of contractors, that Pentagon doesn't know how to grab back control, and that sustainement is currently a shambles, with costs rising and availability dropping fast

The latest GAO stats show a fast degradation of F-35 availability, and full mission-capable rates have dropped to near zero.

AO says the Pentagon "Does Not Have a Clear Pathway to Transition to More Government Sustainment."






Hi

Czech Air Force (and Polish, Finnish, Swiss to name but a few), want to consider how availability rates for US F-35s are falling, costs are rising. and then want to think whether the US taxpayer will want to to sweat F-35 exports to pay its own bills?

Spoiler alert: they will.

Pretty much everything the JPO (and US industry) told you about F-35 costs was, well, a lie.

This estimable @USGAO notes that US F-35 sustainment costs have risen $68bn over the past 2-3yrs.

​​​​​​​If the USAF can't get F-35 spares, do you think you'll be at the front of the queue?
​​​​​​​
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Old 23rd Sep 2023, 04:18
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I remember the days when readiness rates of that nature were classified.
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Old 23rd Sep 2023, 07:45
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Article going into the above report in depth.

https://www.defensenews.com/air/2023...s-costly-slow/

GAO blasts contractor-led F-35 maintenance as costly, slow



Report: https://s3.documentcloud.org/documen...-23-105341.pdf

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