F-35 Program - General Discussion

[FORBIN]

Wrong. The RAAF already has F-35 delivered with Block 3F software. It is in service and has been for months.

yes but exist many customers and i can't remenber all … and majority are 2a or 2B and 3i for soon modified in 3F
And surely the first Aussies are not yet modified.

 

[SpazSinbad]

IIRC the first two Australian F-35As will be modified to 3F standard by the end of this year. Meanwhile....

RAAF accepts three more F-35As 09 Apr 2018 Andrew McLaughlin

"The RAAF has formally accepted three more F-35As from Lockheed Martin at the Integrated Training Centre at Luke AFB in Arizona. After rolling out and taking flight for the first time in December and January, F-35As A35-003, 004 and 005 were accepted into the ITC in early March. The new aircraft are the first JSF international partner aircraft to be delivered with the latest Block 3F operational flight program software load...." RAAF accepts three more F-35As - Australian Aviation

The forecast is for Lightning 01 Feb 2018 Nigel Pittaway

"...“We’re now very confident that we’ll have 3F in our aircraft, which come off the production line in 2018 and our first two aircraft will be upgraded to 3F configuration during the year as well,” AVM Gordon said...." The forecast is for Lightning - Australian Defence Magazine

 

[ngatimozart]

yes but exist many customers and i can't remenber all … and majority are 2a or 2B and 3i for soon modified in 3F
And surely the first Aussies are not yet modified.

As you have been warned elsewhere, modify your posting behaviour or face sanctions from the Moderators. I strongly suggest that you read back through threads before making claims. Secondly SpazSinbad and Assail were both serving RAN officers with seagoing experience and in SpazSinbad's case he was RAN Fleet Air Arm. They are what are known as consummate defence professionals.

 

[Air Force Brat]

How does one know the G being pulled? Usually the story goes that less than the maximum G is used during these demonstrations to allow for a safety margin to pull 6 G for example in an otherwise 5G maneuver to avoid catastrophe (if required) but otherwise not OVER G the demo aircraft unnecessarily. Pulling max. G at any time without a margin for error is a recipe for ….. just add your poison.

Without sitting in the cockpit, and looking at the G meter, we are limited to educated guessing, but that maneuver at 3.55 is a very HARD pull, the A model is limited to 9Gs by the FCS,,, pull as hard as you like, and there's no way you can over G that aircraft in smooth air. Spaz its standard operating procedure that aircraft are stressed to 1.5 times their max G rating..

So a civilian aerobatic aircraft, rated at 6G's positive and 3G's negative is actually built to 9G's positive, and 4.5G's negative, so a tremendous safety margin is built in. Our old 172 is rated at 3.8 G's in the normal category at gross weight, and 4.2 G's positive in the utility category with 2 up and reduced fuel..

So the F-35A is built to withstand 13.5 positive G's, and we know for a fact that AF-02 was flown to 9.9 G's positive with the FCS "opened up" at Edwards AFB during test, it was also flown to 73 degrees positive angle of attack, and later in max AOA testing to 105 degrees angle of attack. However the FCS limits the A model to 50 degrees angle of attack and 9G's positive.. so the A model at Paris, and the A model at Farnborough were flown with the block 3F software limits in place

So that margin you're concerned with is already built into the F-35A, Billy Flynn flew an A model at Paris last year, and I'm not sure who flew the display at Farnborough, Billy's performance in Paris was amazing, but RIAT was a very near Max Effort.. in that final turn and burn climb out.

As Mr. Forbin has pointed out the B model is limited to 7G's positive, and the C model with larger wings and tail is limited to 7.5G's positive, they are both excellent performers, and highly resistant to departure, as is the A model.

 

[SpazSinbad]

OH please: "...Spaz its standard operating procedure that aircraft are stressed to 1.5 times their max G rating...." I am talking about NOT overstressing (using allowed G available - NOT the structural limit of) the airyplane. It is about having a margin of G available for those times it is needed - especially when the display aircraft is close to the ground. So speculate away because that is all it can be. You can imagine all you wish about flying a display aircraft close to the ground however back in the day I did it (but not with these aircraft of today of course). Just ogling YouTube videos can only be speculation. OMG it is a wonder you have not done a turn rate also (but I jest). You again can only speculate about Paris unless told otherwise. I doubt any serving authorizing officer would allow maneuvers to be done at maximum G - without a margin for error - for safety.

Meanwhile I cannot imagine a pilot just hoicking the stick willynilly and letting the FCS 'limit the aircraft'. In my world pilots fly - whilst the FCS may aid them in extremis, the pilot will fly to a limit (minus a margin for error / safety during a flying display). For sure in combat they will fly to the limit if needed. Usually if an aircraft goes over the max. G limit (depending on overG) it will be grounded for inspections that may be quite invasive, taking some time. This is when the pilot fronts the authorizing officer to 'please explain' (with consequences subsequently perhaps).

 

[FORBIN]

IIRC the first two Australian F-35As will be modified to 3F standard by the end of this year. Meanwhile....

RAAF accepts three more F-35As 09 Apr 2018 Andrew McLaughlin

The forecast is for Lightning 01 Feb 2018 Nigel Pittaway

Wrong. The RAAF already has F-35 delivered with Block 3F software. It is in service and has been for months.

After many annoucements, reports with in more the fools around… etc... some mentionned 2019... finaly yet delivered and you imagine well impossible modified especialy US fleet the more big for what i talk mainly in few months ofc

Modified a Bl2a/2B in 3F cost about 13 millions not enormeous they are 90 birds
Why the F-35?: F-35: Retrofit cost projections drop by almost half a billion dollars

Quite sure to Hill all 34 FS birds get modified for end of year the 4 FS wich have now 16 receive 1.5 - 2 by month full for end of year get new 3F and after 421 FS

AIM-9X only internaly would require developing a special launcher, or the AIM-9X would need to be upgraded to allow for ejection launches as AIM-120 rather than just rail launches.
I have posted a pic deleted !

 

[south]

yes but exist many customers and i can't remenber all … and majority are 2a or 2B and 3i for soon modified in 3F
And surely the first Aussies are not yet modified.

I doubt any serving authorizing officer would allow maneuvers to be done at maximum G - without a margin for error - for safet

Meanwhile I cannot imagine a pilot just hoicking the stick willynilly and letting the FCS 'limit the aircraft'. In my world pilots fly - whilst the FCS may aid them in extremis, the pilot will fly to a limit (minus a margin for error / safety during a flying display). For sure in combat they will fly to the limit if needed. Usually if an aircraft goes over the max. G limit (depending on overG) it will be grounded for inspections that may be quite invasive, taking some time. This is when the pilot fronts the authorizing officer to 'please explain' (with consequences subsequently perhaps).

Spaz: I know of at least one front line aircraft type where the display is performed generally using full back stick. The margin for error is built in by padding the altitude in recovery gates.

Additionally the whole reason to build an FCS limiter (G, AOA) is such that Pilots don’t need to use brain capacity to “fly to a limit”, and they can fight the jet.

 

[SpazSinbad]

Let us all see an F-35 pilot talking about a display and I'll be convinced. Do you have any references for how the F-35 is flown in a display? Do you have info about the 'recovery gates'?

 

[south]

Let us all see an F-35 pilot talking about a display and I'll be convinced. Do you have any references for how the F-35 is flown in a display? Do you have info about the 'recovery gates'?

I’m not talking about F-35 reference the display, it is a different type. You just said that’s not the way an authorising officer would let it be done. Times have changed, it is actually easier, more predictable and more repeatable to fly full backstick in some regimes, letting the thousands upon thousands of man hours spent in airframe design, fluid dynamics, FCS software and control laws work the stuff out, rather than finessing the aircraft.

Regardless of what you believe the FCS limiters on most western fast jets since the F-16/18 lets you pull full back stick to the limiter and it will limit G (or AOA, type dependant) to prevent overstress. The less modern types (F-16/18) are slightly fallible depending on configuration. The more modern types (e.g Typhoon) essentially cannot be overstressed, the FCS is that good.

 

[SpazSinbad]

So no references to these 'facts'? Why then does only your word on this count? Have you flown these aircraft types? How does the pilot get more G if / when required due to safety when close to the ground? I'll guess there must be an override switch to the FCS limiter? Certainly F-35 test pilots had such a switch in the test configured orange wire aircraft. I thought we were referencing the F-35 display. How do these other things you speak about become relevant then?

 

[StobieWan]

So no references to these 'facts'? Why then does only your word on this count? Have you flown these aircraft types? How does the pilot get more G if / when required due to safety when close to the ground? I'll guess there must be an override switch to the FCS limiter? Certainly F-35 test pilots had such a switch in the test configured orange wire aircraft. I thought we were referencing the F-35 display. How do these other things you speak about become relevant then?

Have a read of this - I'm not a pilot so you might be able to extract more out of it than I can :

Semper Lightning: F-35 Flight Control System | Code One Magazine

It certainly seems to indicate that the FCS limits G forces in different ways in different regimes.

My flight experience is limited to "can I have ice with my scotch please" so I'd be interested in what you make of it.

Specifically

"What about high-g maneuvering, up-and-away? For symmetric maneuvers, CLAW’s got our back: As long as we’re not rolling or yawing, we can slam the stick full aft or (ugh) forward, at any speed, at any loading. CLAW will keep g within NzW limits[4]."

 

[SpazSinbad]

Thanks I had forgotten that excellent article. I'll excerpt what I think is important from the long article with BOLD to highlight more. The case of F-35 CLAW protecting from G overstress is only in the case of stick full back with no roll (I had forgotten that part) but remembered all the caveats about 'when rolling'. Reading the footnotes [4] & [5] as above/below are important for further understanding. However the aircraft can be 'overstressed' by the pilot in circumstances described and which I'll imagine may occur in a low level flight display. What a shame this first in a series was not continued and CODE ONE seems to be no more. For sure the F-35 CLAW is amazing (especially for 'unusual regimes' such as STOVL) while my impression/comment is that the pilot still flies the airyplane with the CLAW keeping him out of trouble except in exceptional circumstances. I would regard a low level flying display as 'exceptional circumstances'. Billie Flynn practiced his Paris Display a lot with a team of flight engineers amongst others to get it all SAFE and within the bounds of the restrictive rules of the display site. Like most others I can only read about these issues without having flown such an aircraft.

"...Protecting Us From Ourselves
The control limiters in the F-35 – love them or hate them – are there to help. They not only make the airplane safer, but also more effective, by allowing us to fly aggressively without worrying about breaking something or losing control.

But flying the F-35 is not completely carefree. The control engineers had to give us some rope in a few places, since doing otherwise would have compromised capability and possibly even safety. So it’s important for us to understand what’s protected and what isn’t....

…What about g? We’re mostly protected, but not completely. Interestingly, the protection is least where the maneuvering limits are the lowest: in powered approach (PA) and aerial refueling (AR). The limits in those modes are 3g and 2g, respectively, and there’s nothing to keep us from exceeding them. Why not? Because, while those limits are more than adequate for normal ops, there might be times when we need to exceed them to avoid hitting something – such as the ground, or the tanker – and our CLAW engineers have wisely decided that running into things would probably be worse than busting the g limit. So they let us bust the limit.

What about high-g maneuvering, up-and-away? For symmetric maneuvers, CLAW’s got our back: As long as we’re not rolling or yawing, we can slam the stick full aft or (ugh) forward, at any speed, at any loading. CLAW will keep g within NzW limits [4].... [then rolling/yawing examples]

...The bottom line: If you’re on the g-limiter and want to roll, back off a little, then roll. This will not only keep you within the rules, it will give you a better roll rate in the bargain. If you can’t back off – because, say, you’re trying not to hit the ground, or trying not to get shot (and I don’t mean by your buddy during BFM) – then do what you need to do! The worst thing that will happen is that you’ll trip an OVER G advisory or an overload HRC,[5 ...CLAW should in all cases prevent actual overload to failure, but during rolling maneuvers it may allow one of these indications to trip, requiring a maintenance inspection.] and have to explain your heroic act to the maintenance officer when you return. Presumably, the maneuver will be worth the airframe life you expend...."

 

[Air Force Brat]

OH please: "...Spaz its standard operating procedure that aircraft are stressed to 1.5 times their max G rating...." I am talking about NOT overstressing (using allowed G available - NOT the structural limit of) the airyplane. It is about having a margin of G available for those times it is needed - especially when the display aircraft is close to the ground. So speculate away because that is all it can be. You can imagine all you wish about flying a display aircraft close to the ground however back in the day I did it (but not with these aircraft of today of course). Just ogling YouTube videos can only be speculation. OMG it is a wonder you have not done a turn rate also (but I jest). You again can only speculate about Paris unless told otherwise. I doubt any serving authorizing officer would allow maneuvers to be done at maximum G - without a margin for error - for safety.

Meanwhile I cannot imagine a pilot just hoicking the stick willynilly and letting the FCS 'limit the aircraft'. In my world pilots fly - whilst the FCS may aid them in extremis, the pilot will fly to a limit (minus a margin for error / safety during a flying display). For sure in combat they will fly to the limit if needed. Usually if an aircraft goes over the max. G limit (depending on overG) it will be grounded for inspections that may be quite invasive, taking some time. This is when the pilot fronts the authorizing officer to 'please explain' (with consequences subsequently perhaps).

Well, you sir are in luck, the USAF flight demo narrator called it at 9G's, stating over the PA, "as he accelerates through this next turn, the pilot will weigh 9 times his normal weight", that is on the "Knight Productions" video, or you could check the official transcript, I realize he's not pulling the stick and watching the G meter, so maybe it was 7 or 8, but that was the plan, for a very high G break-out from airshow center.

 

[SpazSinbad]

OK - I'll take it that 'a level turn at 9G or close to nine G' was performed (with no to little roll). However we don't know how he pulled the stick. Pilots will fly their aircraft. Relying on a limiter when pointing toward the ground is fraught. Air Display Pilots will have a safety margin for 'mum & the kids'. Who is to say the pilot pulled only 8.5 G (instead of 9 G), how do we know otherwise. Air show pilots know spectators cannot tell the difference so their displays will have margins for error corrections. A 7 G display may well have been a 6.5 G display in reality, whilst the upgrade display may well be 8.5 G instead of 9 G. How can we tell the difference? However a 6.5 G compared to an 8.5 display will have differences - if we can remember them. We can speculate but I suggest being certain of parameters in air displays is not realistic. Any pilot does not want to 'down' the aircraft unnecessarily, so the airshow pilot will want to have a good aircraft for the next show and not raise the hackles of support personnel. And yet if he needs to overstress the aircraft to save it and his skin - successfully - then he will do that. I recall the Thunderbird F-16 pilot ejecting at very low level after attempting to recover from entering a 'loop' maneuver at too low height because he did not have a correct airfield altitude set beforehand. Human error awaits everyone.

BTW an F-35 pilot can probably see the G meter in the vHUD (virtual HUD) in the HMDS (I'm not certain of all the flight parameters that can be seen but it makes sense). Otherwise glancing at the G meter (within reason) is not out of a pilot remit. They are flying the aircraft - they need to know this stuff. The graphic of the vHUD display [left column] shows 1.0 G: Log in to SlideShare (PDF 0.5Mb)

 

[south]

It is well established that modern FCS provides envelope protection, whether that be in fighters, or airliners... Indeed - that is the entire purpose... to think that the pilots do not use the limiters in an air show or indeed routine training is naive. I have been lucky enough to know enough FJ display drivers from two different Air Forces to be comfortable with everything I have said.

Regarding one of your questions, The FA18 has a “paddle” that airspeed dependant can give 33% more G with a corresponding reduction in turn radius. I believe the F-16 has a Cat1/CatII stores switch that can also change the limiter behaviour. More modern types have more robust protection; witness the F-35 above - if you pull straight back you will not overstress. The Typhoon has rolling G protection as well as symmetrical G.

Just as I know one Air Force that pads out their Gate height, using Full back stick initially and then “letting down”, I know another airforce that does exactly as what you say spaz (targets an AoA value for consistent turn performance, and keeps some AOA/G up their sleeve for “Mum and the Kids”). Either way is not wrong - just different; largely owing to different handling characteristics in different airframes. The fact that these aircraft are flown in a different manner to what you are familiar with in the mighty A-4 is not wrong - just different.

Anyway; enough and back to the F-35z

 

[SpazSinbad]

My thoughts on above would be: an airshow performance is NOT like combat training. Combat training takes place with a 'hard deck' thousands of feet AGL most likely - giving pilot a lot of room to recover. An airshow has a much lower 'do not go below' height above ground/crowd & stay on the show line away from crowd etc with only a calculated safe margin for error. Combat training 'hard deck' is virtual - airshow hard deck is the ground, with people and other assets in close proximity. Combat Training usually is over water or over special training areas sparsely inhabited. There is more at risk during an airshow so there is a lot more care taken.

Somehow I have to take your 'assurance' that as a non-pilot I'm guessing you have understood pilot speak from air show pilots of two different air forces. Why be so coy? What air forces - what aircraft etc.

 

[south]

Which is why the airshow qualification is tightly held and supervised, with currency requirements. Including a significant work up that starts at medium level before progressing lower and lower, as I am sure you know.

 

[SpazSinbad]

Yes I know this and there are safety margins aplenty. Still no word on how you know this stuff.

 

[StobieWan]

Thanks I had forgotten that excellent article. I'll excerpt what I think is important from the long article with BOLD to highlight more. The case of F-35 CLAW protecting from G overstress is only in the case of stick full back with no roll (I had forgotten that part) but remembered all the caveats about 'when rolling'. Reading the footnotes [4] & [5] as above/below are important for further understanding. However the aircraft can be 'overstressed' by the pilot in circumstances described and which I'll imagine may occur in a low level flight display. What a shame this first in a series was not continued and CODE ONE seems to be no more. For sure the F-35 CLAW is amazing (especially for 'unusual regimes' such as STOVL) while my impression/comment is that the pilot still flies the airyplane with the CLAW keeping him out of trouble except in exceptional circumstances. I would regard a low level flying display as 'exceptional circumstances'. Billie Flynn practiced his Paris Display a lot with a team of flight engineers amongst others to get it all SAFE and within the bounds of the restrictive rules of the display site. Like most others I can only read about these issues without having flown such an aircraft.

Many thanks - that helps me understand a bit better what's happening in the 'pit!

 

[aussienscale]

The turn you highlighted at 3:55 isn’t beyond the capability of most 4th gen, certainly other high AOA jets like F-18 series can do extremely similar.

Personally I reckon the pilot made a slight error - note the unloading of AOA at 3:57 and then another little pull to keep the nose coming around another 10-20 degrees. Normally in the displays the pilots (of all display aircraft) try to keep manoeuvres consistent and smoothly linked to avoid little bobbles; it makes it look better. Stuff like this is a big focus on their work ups (both in pitch and roll). But that’s just me being hyper critical. This jet is the Future of most western air arms, I reckon it will turn out alright.

Appreciate the insights, I had noticed that in the turn at 3:55 and had made the assumption that is was the FCS kicking in stabilising the plane in the turn as I had seen little "flutters" like it before not just on the JSF but other more modern aircraft. As is widely reported/known, a lot of the modern designs are fairly unstable and the flight controls do a lot of background work keeping things on track, had not considered it a pilot induced correction, but looking at it again it makes sense.

Cheers