F-35 Cancelled, then what ?
glad rag: Oh dear, obviously my post was FAR to subtle for you sd....
Engines: So, in around 13 days, 98 flights and 73 flying hours, from 6 jets. From a small deck and a tiny hangar. Not bad going, in my book
Nice to see the UK folks imbedded into the trials and USMC squadrons.
Engines: 2. Invincible class lift (not elevator, LIFT) size had absolutely no effect on design of any of the F-35 variants. Certainly not overall length. There was never an endorsed requirement for the F-35B to go down the lift. It was considered, but never included as a formal requirement
An older and unreferenced source, perhaps when we were still in the JSF stage (pre down select) here :F-35B Joint Strike Fighter
states "The USMC STOVL aircraft must be compatible with and operationally supportable from CVN-68 (NIMITZ), LHA (TARAWA), and LHD (WASP) Class Ships. The UK STOVL aircraft must be compatible with the flight, ramp, and hangar deck layouts of CVS (INVINCIBLE) Class Ships." Again perhaps not a formal requirment, but was in the literature at the time.
A related interesting paper on ship design influencing the JSF linked below. Paper titled "the Influence of ship configuration on the design of the Joint Strike Fighter" notes the vast differences of ships the JSF would operate from influenced JSF design. Good review of spotting size, elevator/lift size (see table 2) seems to indicate that the INVINCIBLE size likely had some influence. Good discussion on spotting size, that the US Marines did not specify a spotting size or wingspan, or even weight, but that 6 had to fit behind a LHA/LHD island without crossing the "foul" line, or having to move an adjacent plane. That resulted in a wingspan constraint of no more than 35 feet. Then the paper moves to elevator/lift size and hangars and lists the 55x32 foot size of the INVINCIBLE as a factor. So I offer maybe you can have contraints or influences without a requirement....
http://www.google.com/url?sa=t&rct=j...eQCyk8S8rS3FcA
But it seems by the time the B was ordered, it has a 35 foot wingspan (wider than the INVINCIBLE lift). So perhaps the requirment to fit on the INVINCIBLE faded away when it was realized that a B would never fly from an INVINCIBLE. Or as stated was a consideration, but perhaps not acted upon, and helped drive the move to bigger UK carriers. The program has gone through many changes.
All the above just for banter and discussion....
Spot on on the flight deck material. I work just across the yard that has done the flight deck mods for the WASP and more recently the BATAAN. Much effort has gone into this deck coating, and I would expect it got much attention during this eval.
Last edited by sandiego89; 28th May 2015 at 18:46.
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Much effort has gone into this deck coating, and I would expect it got much attention during this eval.
...bloke making a very careful walk-around visual check of the landing spot at 4:15-4:45.
Engines:
As for the wingspan: page 5 here.
http://www.dtic.mil/dtic/tr/fulltext/u2/a399988.pdf
In theory they could have gone with a bigger wing for the A, but - from my familiarity with the program at the time - having three wing sizes would have been a big negative in the source selection.
A LockMart guy recently told me about the Invincible LIFT standard. (He was correcting my view that it had to do with Wasp ELEVATORS.) I am not sure it was in effect at contract award, but it was a requirement late enough to drive the design.
We can talk terms all day, but tons of metal doing nothing for the mission or structural strength sound like deadweight to me. I don't disagree that the F-35C is a porker; a better comparison is the OEW delta (about 600 kg IIRC) between Rafale C and Rafale M.
The Marines have carried a forward-basing CONOPS for the Harrier for decades, with the approval of lots of people wearing the same kind of rank insignia as the chaps who approved the Schlieffen Plan, the K-class submarine and the Boulton-Paul Defiant, among other brilliant ideas from military professionals. They have exercised that CONOPS more or less once per war. I predict the same for the wonderfully named M-FARP.
As for the wingspan: page 5 here.
http://www.dtic.mil/dtic/tr/fulltext/u2/a399988.pdf
In theory they could have gone with a bigger wing for the A, but - from my familiarity with the program at the time - having three wing sizes would have been a big negative in the source selection.
A LockMart guy recently told me about the Invincible LIFT standard. (He was correcting my view that it had to do with Wasp ELEVATORS.) I am not sure it was in effect at contract award, but it was a requirement late enough to drive the design.
We can talk terms all day, but tons of metal doing nothing for the mission or structural strength sound like deadweight to me. I don't disagree that the F-35C is a porker; a better comparison is the OEW delta (about 600 kg IIRC) between Rafale C and Rafale M.
The Marines have carried a forward-basing CONOPS for the Harrier for decades, with the approval of lots of people wearing the same kind of rank insignia as the chaps who approved the Schlieffen Plan, the K-class submarine and the Boulton-Paul Defiant, among other brilliant ideas from military professionals. They have exercised that CONOPS more or less once per war. I predict the same for the wonderfully named M-FARP.
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Sandie,
I might be able to help here. The JSF SRD didn't have any 'implied' requirements, just plain requirements. (However, a (very large) number of 'derived' requirements were developed from the SRD - this process took place as a team effort between LM, the DoD and other customers, especially the UK).
The UK had already decided that it did not want the Invincible class deck, hangar and elevator layouts to affect the aircraft design. This was because they realised that the CVS would probably be leaving service just as the F-35B arrived.
The wording you give in your post is taken from the SRD, and you should note the difference between the US and the UK ship interface requirements:
" The USMC STOVL aircraft must be compatible with and operationally supportable from..CVN-68...LHA and LHD class ships"
"The UK STOVL aircraft must be compatible with the flight deck, ramp and hangar deck layouts of CVF..class ships"
All the UK asked for was that the STOVL aircraft was 'compatible' with the CVS layout, not 'operationally supportable'. That was taken to mean that as long as the F-35B could be parked on the flight deck or the hangar deck, it was OK. And the CVS elevator was deliberately omitted, as the UK didn't want it to impact the design. Yes, I know it sounds like a 'cop out', but the UK MoD had already realised that trying to operate F-35Bs effectively from CVS would not be a cost effective exercise.
The only UK ship specific requirement that did affect the design was a separate requirement for the aircraft to be able to execute a STO off a CVS class ramp. Later on, the UK CVF team had LM and BAES design a more optimised ramp profile for the QEC class.
The paper you provided a link to (for which many thanks) was familiar to me when I worked on the F-35 ship suitability team. The statement about the 35 foot wingspan limit from the LHD was made before more detailed option studies were done into different deck spotting arrangements, and other stuff. It wasn't set out in the SRD, nor, to my knowledge, was it set out as a formal derived requirement. The main driver for F-35B wingspan, in my recollection, was the need to reduce airframe weight as far as possible. However, it's certainly true that LHD deck spotting had an influence.
I hope this helps a bit. As ever, there are a number of factors that drive an aircraft's design at various times in the design and test process. You don't always see clear 'cause and effect' going on.
Best Regards
Engines
I might be able to help here. The JSF SRD didn't have any 'implied' requirements, just plain requirements. (However, a (very large) number of 'derived' requirements were developed from the SRD - this process took place as a team effort between LM, the DoD and other customers, especially the UK).
The UK had already decided that it did not want the Invincible class deck, hangar and elevator layouts to affect the aircraft design. This was because they realised that the CVS would probably be leaving service just as the F-35B arrived.
The wording you give in your post is taken from the SRD, and you should note the difference between the US and the UK ship interface requirements:
" The USMC STOVL aircraft must be compatible with and operationally supportable from..CVN-68...LHA and LHD class ships"
"The UK STOVL aircraft must be compatible with the flight deck, ramp and hangar deck layouts of CVF..class ships"
All the UK asked for was that the STOVL aircraft was 'compatible' with the CVS layout, not 'operationally supportable'. That was taken to mean that as long as the F-35B could be parked on the flight deck or the hangar deck, it was OK. And the CVS elevator was deliberately omitted, as the UK didn't want it to impact the design. Yes, I know it sounds like a 'cop out', but the UK MoD had already realised that trying to operate F-35Bs effectively from CVS would not be a cost effective exercise.
The only UK ship specific requirement that did affect the design was a separate requirement for the aircraft to be able to execute a STO off a CVS class ramp. Later on, the UK CVF team had LM and BAES design a more optimised ramp profile for the QEC class.
The paper you provided a link to (for which many thanks) was familiar to me when I worked on the F-35 ship suitability team. The statement about the 35 foot wingspan limit from the LHD was made before more detailed option studies were done into different deck spotting arrangements, and other stuff. It wasn't set out in the SRD, nor, to my knowledge, was it set out as a formal derived requirement. The main driver for F-35B wingspan, in my recollection, was the need to reduce airframe weight as far as possible. However, it's certainly true that LHD deck spotting had an influence.
I hope this helps a bit. As ever, there are a number of factors that drive an aircraft's design at various times in the design and test process. You don't always see clear 'cause and effect' going on.
Best Regards
Engines
Great stuff, thank you Engines, especially on the SRD and pointing out the distinction on INVINCIBLE "compatabilty" vs "operationally supportable". Seems that the B on the INVINCIBLE would have been an interim step to do some trials, keep some limited capability and the skills warm until the new carrier came. Of course that did not quite work out....
I did enjoy that paper, really makes one appreciate the challenges and requirements, derived and otherwise, the team had to work with. Thank you.
I did enjoy that paper, really makes one appreciate the challenges and requirements, derived and otherwise, the team had to work with. Thank you.
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Sandie,
Thank you.
LO,
I suggest that we should agree to disagree. Weight was a big issue on all three variants, and wing sizing was driven by a range of factors. The fact is that the A model (and the B model) have plenty of wing for what they were required to do. Weight drove a short wingspan as much as anything else. The JORD development process confirmed what many already knew - that success in combat depended as much (if not more) on the sensor and data fusion capability and weapons integration of the platform as it did on 'g' capability, or even sustained turn. Big wingspans weren't required.
I simply don't agree that the B's lift system is dead weight. The mission requirement is to operate from a ship. The lift system provides that. By your definition, landing gear is dead weight on an F-22. The F-35B is a STOVL aircraft. A lift system is essential to its mission. Clear to me.
The LockMart guy was wrong. As I said, compatibility with Invincible lifts was certainly looked at (diagrams of folding wingtips were drawn, but they were never anywhere being designed). The Invincible lift dimensions did not drive any aspects of F-35 design. If you want to disagree on this, feel free.
The F-35C isn't a 'porker' - it's what you get when you want an aircraft that can both fight and strike, with two large internal weapons bays, supersonic capability, and an ability to take off and land from a CVN at high weights. CATOBAR drove wing area and wing span, also the big structural penalties. From my experience on the T-45, I wasn't in the least surprised at the scale of the additional weight on the C.
CONOPS - see Para 5 of my previous reply. I'm done.
Best regards as ever to those working hard to bring new capabilities to the front line in good order. Not much else matters.
Engines
Thank you.
LO,
I suggest that we should agree to disagree. Weight was a big issue on all three variants, and wing sizing was driven by a range of factors. The fact is that the A model (and the B model) have plenty of wing for what they were required to do. Weight drove a short wingspan as much as anything else. The JORD development process confirmed what many already knew - that success in combat depended as much (if not more) on the sensor and data fusion capability and weapons integration of the platform as it did on 'g' capability, or even sustained turn. Big wingspans weren't required.
I simply don't agree that the B's lift system is dead weight. The mission requirement is to operate from a ship. The lift system provides that. By your definition, landing gear is dead weight on an F-22. The F-35B is a STOVL aircraft. A lift system is essential to its mission. Clear to me.
The LockMart guy was wrong. As I said, compatibility with Invincible lifts was certainly looked at (diagrams of folding wingtips were drawn, but they were never anywhere being designed). The Invincible lift dimensions did not drive any aspects of F-35 design. If you want to disagree on this, feel free.
The F-35C isn't a 'porker' - it's what you get when you want an aircraft that can both fight and strike, with two large internal weapons bays, supersonic capability, and an ability to take off and land from a CVN at high weights. CATOBAR drove wing area and wing span, also the big structural penalties. From my experience on the T-45, I wasn't in the least surprised at the scale of the additional weight on the C.
CONOPS - see Para 5 of my previous reply. I'm done.
Best regards as ever to those working hard to bring new capabilities to the front line in good order. Not much else matters.
Engines
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Hang on a minute Engines.
Whilst you are correct about operations from gelded flattop [oops]
Why should the RAF aircraft have to lug about so much
1. dead weight
2. loss of fuel capacity
3. loss of weapons storage. Mind you @£185,000 a pop for smd2 you can see the beancounters eyes light up when it's 4 vs 8 in the bays..
Hmm.
Whilst you are correct about operations from gelded flattop [oops]
Why should the RAF aircraft have to lug about so much
1. dead weight
2. loss of fuel capacity
3. loss of weapons storage. Mind you @£185,000 a pop for smd2 you can see the beancounters eyes light up when it's 4 vs 8 in the bays..
Hmm.
Originally Posted by Engines
I simply don't agree that the B's lift system is dead weight. The mission requirement is to operate from a ship. The lift system provides that. By your definition, landing gear is dead weight on an F-22. The F-35B is a STOVL aircraft. A lift system is essential to its mission. Clear to me.
To many that will operate it, it could well be just dead weight.
Why should the RAF aircraft have to lug about so much
So they all have to be capable of flying off and recovering on the carrier. Otherwise people might think they weren't being serious.......
Joint is great, NaB. I have always been a massive supporter of "jointery", even if I hate the ugly term someone thought up to describe it.
But none of that is the point. The point is that land-based ops, that may require a decent payload and range, MAY be compromised by the constraints imposed on the single model the UK is buying.
If the B model really can do it all, why are other U.S. Forces buying two other models to suit their requirements?
But none of that is the point. The point is that land-based ops, that may require a decent payload and range, MAY be compromised by the constraints imposed on the single model the UK is buying.
If the B model really can do it all, why are other U.S. Forces buying two other models to suit their requirements?
The point is that land-based ops, that may require a decent payload and range, MAY be compromised by the constraints imposed on the single model the UK is buying.
The RAF has a number of other capabilities (Typhoon, Storm Shadow and FSTA) if range/payload are significant concerns.
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The point is that land-based ops, that may require a decent payload and range, MAY be compromised by the constraints imposed on the single model the UK is buying.
On balance and quite a lot of analysis, the RAF clearly values the flexibility and choice presented by use of embarked, DOB (austere strips; either constructed or temp refurbished), or fully established runways, over the relatively small gains in combat radius. Back then nobody anticipated being cuffed with a shorter weapons bay; that and a few other design changes was a STOVL weight issue from c.2005 and, believe me, was hotly contested.
So, to re-iterate the point, the STOVL variant is the RAF and RN's choice. For any Service purchasing it, it is being purchased for its STOVL benefits and therefore the Lift Fan is most certainly not dead weight. It is essential to the concept of why it is being bought by those Services.
Do a Hover - it avoids G
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There are answers to the oft repeated it melts decks and it has dead weight arguments.
The first answer is please note the rubber tyres immersed in the efflux.
The second answer has two parts. One has been mentioned by MSOCS, namely the operational flexibility that a hover capability provides. However this includes many things in addition to the size and type of site - such as it is easier in poor viz and with bad ship motion (both of which were much valued during the Harrier operational trials in the Falklands).
But in addition to these aspects there is a biggy that the hover before land offers that non Harrier pilots may not have considered. If you can hover then the whole need for an accurate end point to the approach to land goes away in both plan position and height. You just need to come to the hover with the touchdown point in view. A whole minute of sliding around in the hover to correct one’s height and position before landing really bores onlookers. A minute is a very long time in those circumstances.
Which brings me at last to the real biggy. This relaxed hover before landing mode means you need very little in the way of fuel remaining (imagine standing on the deck watching one in the hover for two minutes. Two minutes! What is he doing??) This ability to land safely with only a couple of minutes of hover fuel is in stark contrast to conventional ops with any aircraft type. When you join Neil Armstrong in the next life raise the issue with him.
So if you can hover much more of the fuel you start the trip with is available to do the trip. Thus even the (fuel) space taken by the fan is not as wasted as many folk think.
The first answer is please note the rubber tyres immersed in the efflux.
The second answer has two parts. One has been mentioned by MSOCS, namely the operational flexibility that a hover capability provides. However this includes many things in addition to the size and type of site - such as it is easier in poor viz and with bad ship motion (both of which were much valued during the Harrier operational trials in the Falklands).
But in addition to these aspects there is a biggy that the hover before land offers that non Harrier pilots may not have considered. If you can hover then the whole need for an accurate end point to the approach to land goes away in both plan position and height. You just need to come to the hover with the touchdown point in view. A whole minute of sliding around in the hover to correct one’s height and position before landing really bores onlookers. A minute is a very long time in those circumstances.
Which brings me at last to the real biggy. This relaxed hover before landing mode means you need very little in the way of fuel remaining (imagine standing on the deck watching one in the hover for two minutes. Two minutes! What is he doing??) This ability to land safely with only a couple of minutes of hover fuel is in stark contrast to conventional ops with any aircraft type. When you join Neil Armstrong in the next life raise the issue with him.
So if you can hover much more of the fuel you start the trip with is available to do the trip. Thus even the (fuel) space taken by the fan is not as wasted as many folk think.
JF,
I think some have the view that hovering must use a shed-load of fuel as the engine is operating close(ish) to its maximum output. Along the way they forget that the air that is being rammed in is very little when compared to high-speed or low-level cruise. The actual fuel flow is lower than most may imagine.
I think some have the view that hovering must use a shed-load of fuel as the engine is operating close(ish) to its maximum output. Along the way they forget that the air that is being rammed in is very little when compared to high-speed or low-level cruise. The actual fuel flow is lower than most may imagine.
It really doesn't matter who chose the B-Model or for what reasons, the point still remains that the lift fan and other equipment does reduce range and payload. As a result, land-based ops MAY be compromised. It was a simple point. Apart from that, the aircraft that the RAF 'selected' all those years ago wasn't quite the same one we're seeing today.
As for landing fuel, the minima will be set according to circumstances. But it won't matter if they recover the B-Model to the deck on fumes, it still has a significantly reduced combat radius. The use of the relaxed hover mode is also dependent upon bring-back, wod, temp, etc. RVL is not the same as VL in terms of all the advantages.
As for landing fuel, the minima will be set according to circumstances. But it won't matter if they recover the B-Model to the deck on fumes, it still has a significantly reduced combat radius. The use of the relaxed hover mode is also dependent upon bring-back, wod, temp, etc. RVL is not the same as VL in terms of all the advantages.
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JTO,
You're right, it's not huge. As always, JF perfectly explains some key differences between old and new hovering challenges. That said, there are good reasons to be concerned when such a powerful engine's exhaust is only a few inches above the landing surface in the last second or two of touchdown, followed by a rapid engine deceleration and the aircraft moving away to ease thermal feedback from the [now rather warm] surface to ac tyres. So far, the Wasp trials have shown safe, repeatable and reliable STO and VL operations at work and are equally testing ship-air interaction at the highest sortie rate yet done at sea by the USMC with this jet. The UK are involved and learning in order to plan for future sea trials with QEC in 2018.
The USMC will be the first Service in the world to go to sea with a squadron of 5th Gen combat aircraft - we know they won't be fully mission capable in respect of SDD but they will have a tested and confirmed A-A and A-G capability employable from their own ships.
You're right, it's not huge. As always, JF perfectly explains some key differences between old and new hovering challenges. That said, there are good reasons to be concerned when such a powerful engine's exhaust is only a few inches above the landing surface in the last second or two of touchdown, followed by a rapid engine deceleration and the aircraft moving away to ease thermal feedback from the [now rather warm] surface to ac tyres. So far, the Wasp trials have shown safe, repeatable and reliable STO and VL operations at work and are equally testing ship-air interaction at the highest sortie rate yet done at sea by the USMC with this jet. The UK are involved and learning in order to plan for future sea trials with QEC in 2018.
The USMC will be the first Service in the world to go to sea with a squadron of 5th Gen combat aircraft - we know they won't be fully mission capable in respect of SDD but they will have a tested and confirmed A-A and A-G capability employable from their own ships.
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Courtney,
Please educate me then. What are all the advantages you seem to think aren't realised in RVL (particularly SRVL)?
The use of the relaxed hover mode is also dependent upon bring-back, wod, temp, etc. RVL is not the same as VL in terms of all the advantages.
Oh, good Lord, MSOCS, I feel your angst. "Please educate me, then." Really? Did I dare question something about F-35 and its "vertical landings"? Remember, I am NOT a so-called "nay-sayer" so please don't respond to me as if I were.
But I shall explain my point, which was in response to JF. His post was extolling the virtues and all the advantages of coming to the hover, adjusting, moving sideways and plonking on the deck. My point was simply that all that is fine, but it was only a few months ago that extolling the virtues and the necessity to do RVLs instead. Not all the advantages apply equally to both landing modes.
Nothing more than that.
But I shall explain my point, which was in response to JF. His post was extolling the virtues and all the advantages of coming to the hover, adjusting, moving sideways and plonking on the deck. My point was simply that all that is fine, but it was only a few months ago that extolling the virtues and the necessity to do RVLs instead. Not all the advantages apply equally to both landing modes.
Nothing more than that.