F-35 Cancelled, then what ?

[Willard Whyte]

Ooh, now LO, I'm sure someone will come along and patronizingly, pompously, assert that everything is rosy up the '35's ass.

[LowObservable]

P&W has its say too:

Pratt & Whitney Offers Some F135 Explaining | Defense content from Aviation Week

Makes an interesting compare-and-contrast with their propaganda four-to-five years ago.

[Turbine D]

The F135 is the heaviest high-performance fighter engine ever built, weighing 70% more than the P&W F100 and measuring 24% larger in diameter, with consequently larger inertial and gyroscopic forces.

Therein the problem lies. Somehow, during the initial conceptual design, this observation wasn't sorted out properly. Although the engine is a heavy weight, the parts that need to be heavy don't seem to be heavy enough. The stator vanes are locked into the engine casing. IMHO, the integral bladed rotor and their seal teeth, being the best true diameter achievable, seem to be snagged by the stator vane seal grooves, not the other way around. Must have something to do with the engine casing true roundness in the air when the aircraft is maneuvering.

Bennett's dissertation can be condensed: We're good guys, thought we did everything right, didn't work out, don't know the root cause of the problem yet, working the issue, only 60% of the way to the end of development, not to worry, we will eat the added costs for this mishap… Wonder what the future costs of spare parts will be?

[Fox3WheresMyBanana]

A weight penalty for the fix seems likely if there's a stiffness problem. Being a retrofit, it will likely be more than if they'd designed it right in the first place. This being a relatively cutting-edge engine, it may be simply a problem PW where unaware of, but there may be a PW designer somewhere shaking his/her head and saying "I told you so..."

[longer ron]

Turkey..... now about to become a heavier turkey .....
even I cannot joke about it any more... : (

How much to cut off the ski jump and install enough gear to operate a real carrier aircraft...shouldn't be too much..... even for 'shhhhh' - you know who !

[glad rag]

Originally Posted by longer ron

Turkey..... now about to become a heavier turkey .....
even I cannot joke about it any more... : (

How much to cut off the ski jump and install enough gear to operate a real carrier aircraft...shouldn't be too much..... even for 'shhhhh' - you know who !

"It is suspected that the fan blade began cracking three weeks before the fire during a complex manoeuvre in which the pilot put roll, yaw and g-forces on the aircraft simultaneously."

Engine cracks pose fresh delay risk for F-35B - 9/4/2014 - Flight Global

[NITRO104]

Originally Posted by Fox3WheresMyBanana

but there may be a PW designer somewhere shaking his/her head and saying "I told you so..."

Everything does seem to be screaming so...can't believe such dilettantism was let into the high profile project like this one though.
Still, I'm hearing about "engineers" on already alarming almost daily basis, capable of missing an order of magnitude when calculating loads, without even understanding the ballpark where their results should land, so who knows...

[RetiredF4]

"It is suspected that the fan blade began cracking three weeks before the fire during a complex manoeuvre in which the pilot put roll, yaw and g-forces on the aircraft simultaneously."It is suspected that the fan blade began cracking three weeks before the fire during a complex manoeuvre in which the pilot put roll, yaw and g-forces on the aircraft simultaneously."

Do I understand that correct, that such complex maneuvers (did we call those BFM once upon a time?) are not allowed with the F-35 and will break those engines?

[Rhino power]

Originally Posted by RetiredF4

Do I understand that correct, that such complex maneuvers (did we call those BFM once upon a time?) are not allowed with the F-35 and will break those engines?

The manoeuvre which is suspected of starting the fan blade cracking was also described as being 'benign' so, given the current G limit of the F-35 (still 3.5/4?), I think there is potentially even more bad news to come regarding this engine problem...

-RP

[Turbine D]

Do I understand that correct, that such complex maneuvers (did we call those BFM once upon a time?) are not allowed with the F-35 and will break those engines?

I think so. The F-35 really isn't a "fighter aircraft". General Bogdan pretty much alluded to this fact when he described the shortcomings he noted when assuming responsibilities for the program. The best definition as I see it is the F-35 is a gnat, not a fighter.

[Whitewhale83]

Yet the fanboys still insist that the 35 would defeat any current fighter if it came down to a WVR knifefight, mainly due to 'Fifth generation' (™) and 'sensor fusion' (™). But it would seem that currently the Lesser spotted fat Dave cant pull off manoeuvres that even WW2 pilots would have considered 'warming up'.

What is really interesting about the news coming out of P+W is that they hope to know the issue by end of Sept yet are still delivering engines that they will later have to recall and re-engineer once they have come up with a solution. At first it was suggested that it was a faulty batch of titanium, that seems to have dropped and now there is talk of designing in a 'gulley' for that set of blades or reinforcing the whole engine to eliminate flex, that is massive work.

We may never know how much this ends up costing but it is going to be a shocking figure

[Hempy]

Seriously interested in hearing from Engines about all of this. He seems to have disappeared off the planet lately..

The rumour of a serious engine redesign has been around for a while. What is Pratts position on this, what effect does it have on acceptance schedules, and what effect does it have on ongoing maintenance schedules/costs?

These are multi-million dollar questions. Along with the other unconnected issues with this aircraft, it's starting to look like an unmitigated disaster...

[CoffmanStarter]

F-35 Cancelled, then what ?

Well don't worry Chaps ... Our F-35 Desk Officer at the MOD has a Plan B ...

Pictures taken recently at a Top Secret Airbase in Berkshire, here in the UK, reveal the configuration of a totally new single seat Fighter design. According to well placed sources the design offers both Air Defence and Ground Attack capability ...



Image Credit : BBC News/Airbourne Aviation

Also seen in the picture is a further new aircraft design (in final stages of construction) which is believed to be the new StarBus M Falcon MRTT ... which is to be delivered under a further PFI contract to the RAF by StarTanker.

Coff.

[John Farley]

I must say I continue to be surprised at the negative attitude of many posters here following any information about development problems.

As I have said before, any event that shows up weaknesses at this stage of the programme is pure engineering gold when it comes to improving the eventual service standard of any aircraft type.

The F35 is a 60 year programme (that started in 2000) and we are only half way through the second decade.

I would predict that by the end of the next decade it will be well sorted giving 30 years when it will be the aircraft to beat.

[Bigpants]

Value for Money?

John

Well put but is the aircraft going to offer value for money? Is it really the most cost effective solution for the UK?

I fear that Cameron's recent bold statement about keeping both carriers means they will be financially constrained to harbour most of the year and the F35 crews getting 150 hrs a year flying from UK ground bases assuming this aircraft gets a UK release to service.

We shall see but not optimistic about it being a 60 year programme. Would have thought UAVs more likely to take over sooner than that.

[RetiredF4]

John,
i respect your point, but i'm at a loss why those developement problems still exist in the second decade of the aircraft. The jet does not expand the flight envelope into regions totally unknown before. My old Rhino i started flying 1977 flew faster than M2, had 8.5 g's available, could shoot the gun, carry bombs and i never was able to overstress the airframe or the engines in a way that they quit on me.
We didn't have stealth, couldn't take off or land without a suitable peace of runway and our sensors and gadgets could't cope with the ones on later jets. Therefore to expect developement problems on those new areas is understandable, but airframe and engine problems under such a restricted flight envelope like the jet is operated at the moment are hard to understand.

The next question is, what kind of aircraft will fill the gap for the next decade, if you expect some more years until those problems are sorted out?

[LowObservable]

JF - The problem is that it's a lot of trust to put in a concept that is coming up to 18 years of serious-money development and $90 billion in SDD, with 90 production aircraft delivered. "At this stage" - in those terms - you should expect the design to be showing strong signs of maturity.

But even leaving aside engine troubles of the moment, it has yet to reach any form of IOC, fly with more than a few external stores, land on an aircraft carrier, deploy consistently away from main operating bases or be cleared outside a very restricted envelope for service pilots. It's also currently operating at 30-40 per cent readiness rate.

[John Farley]

Bigpants

You ask two very important questions and I have no idea of the facts that would enable them to be answered and I suspect all of the posters here are in the same position.

However this is PPRuNe so we can still offer opinions for what they are worth!

Dealing with value for money I don’t know how you judge the value of any defence expenditure until the period it is intended to cover is past! However a fair bit of the F35 programme money is being spent in the UK (we make back ends of all versions and the RR Lift System for the B) so that keeps people in high quality work plus they pay income tax etc. There has to be value in that. It also keeps our technology base at the leading edge of whatever is going on which has other potential advantages for the UK in the future. Personally I would not like to see us quit all that sort of activity.

As to the cost effectiveness of the B for the UK (assuming the carriers are there to enable our politicians to have their say around the world and they continue to want this) I am confident that the B is a much better choice than the C. Vertical landing is so much easier for the pilot. This makes operations safer with fewer training and currency demands. It also greatly expands the safe ship motion and poor viz operational envelope. Plus it requires only tiny fuel reserves compared with non VL operations. That is not just an opinion but fact. Many of the chaps who went to the Falklands were experienced catapult and arrested landing pilots and they all agreed that they would not have been able to operate in the conditions they found themselves in down there without VL.

In my experience it is hardly possible to overstate the reduction in stress on an approach if you can hover. For the approach to be successful (on land or at sea day or night) all you need to do is drift to a hover with the landing point in sight. You can then take out any lack of approach path accuracy with a bit of hover taxying. A minute in the hover is a very long time (ask any spectator bored by seeing nothing happening) hence the need for relatively tiny fuel reserves compared to normal fixed wing operations.

Going slightly off topic, I actually think the F35B spec (a supersonic and stealthy vertical lander) suits the possible UK carrier use more than it does the USMC for their primary expeditionary close grunt support role where I see the provision of supersonics and stealth as unnecessary – even unhelpful.

[John Farley]

RetiredF4

Therefore to expect development problems on those new areas is understandable, but airframe and engine problems under such a restricted flight envelope like the jet is operated at the moment are hard to understand.

I can appreciate why you feel that. However modern power weight and fuel consumption requirements make big demands on today’s developers. I don’t pretend to know anything much about the F4 but I have flown it. Sure it did Mach 2 but you had better be pointing towards base (and not far away) when you did it! As for combat endurance when the USMC stated ACM trials with their new low fuel consumption turbofan donks in their Harriers back in the early ‘70s they played until their adversaries bingoed and then waited on the range for the next lot to come out to play. That got up a few noses I seem to remember. The only point I am trying to make is that times move on, capabilities improve and this all costs time and money. Lots of it.

Your next question is about what kind of aircraft will fill the gap for the next decade.

I only know what the USMC (not the USAF or UN) have said which is that they intend to start winding down their Harriers between 2027 and 2030. 2030 would be 59 years since they started in 1971.

LowObservable

You are of course right with what you say - we just have a different view on whether those facts are to be expected or not.

Incidentally back in the early ‘70s when the USMC air combat aces had their first look at what their new AV-8As would do, they achieved pitch rates at low speeds which were twice what jet engines were designed to cope with in those days. So the gyroscopic forces caused the fan to rub much to everybody’s consternation and providing much food for the doom merchants of the day. Hey Ho.

[glad rag]

@ JF

" It also keeps our technology base at the leading edge"

I wouldn't want to call an almost two decades old program "leading edge".