Future Carrier (Including Costs)
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WEBF - I may come across as anti-F-35, but it is what it is. It probably should and would have been axed or more thoroughly reconstructed if people had realized in 2008 how deep in the weeds the program was, but it's no use crying over spilt milk (about 250 million tonnes of it at current wholesale rates).
I am deeply pro-anything that comes in on time and on schedule, not that there's a lot of it around, and I also recognize that monocultures introduce vulnerability. (This applies to battleships and the potato in 1840s Ireland.) Oh, and it doesn't take much exposure to global affairs to realize that the "reach" aspect of airpower has never been more important.
MSOCS - On the Internet, nobody knows you're a dog. I could go into painful detail of my experience in systems engineering inside and outside aerospace, but it would really make more sense to engage my arguments (and others') factually from the start.
I am deeply pro-anything that comes in on time and on schedule, not that there's a lot of it around, and I also recognize that monocultures introduce vulnerability. (This applies to battleships and the potato in 1840s Ireland.) Oh, and it doesn't take much exposure to global affairs to realize that the "reach" aspect of airpower has never been more important.
MSOCS - On the Internet, nobody knows you're a dog. I could go into painful detail of my experience in systems engineering inside and outside aerospace, but it would really make more sense to engage my arguments (and others') factually from the start.
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Fair point however your background and experience helps my understanding of your point of view.
I believe you have programmatic views that are fair. To scold operators who think it really is an excellent machine with much potential is a fly in the ointment. Again, perspectives.
I won't debate you on systems engineering because I think my own frustrations of the F-35 Program's past decisions might give us more in common than you'd think, and place us in violent agreement.
You said it... it is what it is. But, it's a great jet. There are a few areas where people think it should be better, but it isn't.
Many countries still going ahead with orders, including my own. There are many, many positives.
I believe you have programmatic views that are fair. To scold operators who think it really is an excellent machine with much potential is a fly in the ointment. Again, perspectives.
I won't debate you on systems engineering because I think my own frustrations of the F-35 Program's past decisions might give us more in common than you'd think, and place us in violent agreement.
You said it... it is what it is. But, it's a great jet. There are a few areas where people think it should be better, but it isn't.
Many countries still going ahead with orders, including my own. There are many, many positives.
Ecce Homo! Loquitur...
An aside on FJ underwing tanks and AAR. Putting on tanks full with fuel is (almost) a zero sum game, you burn the extra fuel taking off and climbing to height with very little gain once drag is factored in. The real gain is made getting airborne with empty tanks and filling to full from a tanker once at height - but that requires, for a formation, a land based tanker with a substantial offload - ideally shortly before penetrating hostile airspace where it can operate safely.
To answer an earlier question, it makes sense to launch the FJs close to the target to maximise on station time as opposed to transit time; and as FJs tend to expend munition also cycle time to replace them and turn them - problems a tanker doesn't encounter. So launching FJs from a carrier to meet a tanker which has has to transit 2+ hours to the RV does make a lot of sense in some theatres.
To answer an earlier question, it makes sense to launch the FJs close to the target to maximise on station time as opposed to transit time; and as FJs tend to expend munition also cycle time to replace them and turn them - problems a tanker doesn't encounter. So launching FJs from a carrier to meet a tanker which has has to transit 2+ hours to the RV does make a lot of sense in some theatres.
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Completely agree ORAC, and is exactly what the USN has pretty much done for the last 15 years!
There really only is Land-based AAR for jet operations.
There really only is Land-based AAR for jet operations.
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Now about this Air Refueling requirement, what tankers?
And what systems are in place to ensure the fuel IS dispensed at the correct chilled temperature, I take it QUALITY is still a program driver?
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Welcome back to the debate Rag.
What tankers? Take your pick - of the 8/9 Voyager we have, to the plethora of US and European tankers available.
Chilled fuel? That issue doesn't seem to be as much of an issue any more. Also, I guarantee fuel out of an airborne AAR platform is cool - as cool as my bar chat. 😎
Quality? Stumped me there so I'll guess: Contaminated fuel affects all platforms, fairly equally. It is tested - you may have had to do this when you serviced aircraft? All I know is that, at the bases where I've served, the fuel was rarely, if ever, below the required spec. A4 Logs POL guys did a very important job in that regard because they knew if they didn't, it affected output.
What tankers? Take your pick - of the 8/9 Voyager we have, to the plethora of US and European tankers available.
Chilled fuel? That issue doesn't seem to be as much of an issue any more. Also, I guarantee fuel out of an airborne AAR platform is cool - as cool as my bar chat. 😎
Quality? Stumped me there so I'll guess: Contaminated fuel affects all platforms, fairly equally. It is tested - you may have had to do this when you serviced aircraft? All I know is that, at the bases where I've served, the fuel was rarely, if ever, below the required spec. A4 Logs POL guys did a very important job in that regard because they knew if they didn't, it affected output.
Last edited by MSOCS; 3rd Apr 2017 at 20:56.
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Glad,
I might be able to help here.
Managing the thermal loads (keeping stuff cool and keeping stuff warm and moving heat energy around) in any combat aircraft is quite a hard job. In stealth aircraft, it's harder because you have less freedom to scoop cold air in and dump hot air overboard. F-35 (all variants) therefore has had quite a challenge to achieve this under all and any conditions.
A standard technique is to use the fuel in the tanks as a heat sink to soak up excess heat. (You might have heard that one problem the Nimrod AWACS Mk3 never solved was excess heat buildup in the wing fuel tanks).
F-35 uses this technique, (as well as many others) but early on in the programme it was realised that at really extreme conditions (over 45 degrees C, heat soaked for many hours and warm fuel) there were corners of the flight envelope where the thermal management systems were having trouble coping.
The F-22 and B-2 had both had the same problem, and at the same locations - US air test establishments in the hot south west, e.g. Palmdale and Yuma. The solution was to arrange for chilled fuel to be made available for test flying to allow unrestricted operations. At no time was chilled fuel required for deployed operations.
Same for F-35. It used the legacy chilled fuel supplies to support test flying, but chilled fuel is not required for deployed ops. In any case, fuel from AAR platforms is usually cool, as is fuel from ships.
Hope this helps,
Best Regards as ever to all those working the logs and support stuff,
Engines
I might be able to help here.
Managing the thermal loads (keeping stuff cool and keeping stuff warm and moving heat energy around) in any combat aircraft is quite a hard job. In stealth aircraft, it's harder because you have less freedom to scoop cold air in and dump hot air overboard. F-35 (all variants) therefore has had quite a challenge to achieve this under all and any conditions.
A standard technique is to use the fuel in the tanks as a heat sink to soak up excess heat. (You might have heard that one problem the Nimrod AWACS Mk3 never solved was excess heat buildup in the wing fuel tanks).
F-35 uses this technique, (as well as many others) but early on in the programme it was realised that at really extreme conditions (over 45 degrees C, heat soaked for many hours and warm fuel) there were corners of the flight envelope where the thermal management systems were having trouble coping.
The F-22 and B-2 had both had the same problem, and at the same locations - US air test establishments in the hot south west, e.g. Palmdale and Yuma. The solution was to arrange for chilled fuel to be made available for test flying to allow unrestricted operations. At no time was chilled fuel required for deployed operations.
Same for F-35. It used the legacy chilled fuel supplies to support test flying, but chilled fuel is not required for deployed ops. In any case, fuel from AAR platforms is usually cool, as is fuel from ships.
Hope this helps,
Best Regards as ever to all those working the logs and support stuff,
Engines
Using tank fuel as a heat reservoir can be dumb. You end up with ridiculous min fuel states. No problem using fuel on its way to burn, except, it has its limits. As far as avoiding heat signature, well, there is a whacking great big one that should be dwarfing the systems heat load!
Overall, don't blindly think of the fuel load as an easy heat sink, it can easily become a very heavy deadweight!
OAP
Overall, don't blindly think of the fuel load as an easy heat sink, it can easily become a very heavy deadweight!
OAP
Ecce Homo! Loquitur...
IIRC one of the major drawbacks on the Nimrod Mk3 in using the fuel as a heat dump was the reduced performance/TOT - and we are talking hours not minutes - hence keeping the radar offline whilst in transit. One presumes hot fuel has the same drawback in all types and a more problematic effect in a shorter range aircraft.
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Sandie, others,
Thanks for coming back. I'm not surprised that the F-117 had similar issues, as the key factors driving the issue were similar.
OAP, any decision can be 'dumb' - but using fuel as a heat sink is a sensible measure - it all depends how you implement it and schedule the thermal management system. Yes, of course the engine is generating big heat loads, but happily quite a bit of it gets flung out of the back of the aircraft. Thermal problems can (and do) arise all over highly integrated aircraft, in places such as flying controls and even antenna installations.
In designing a combat aircraft, it's rare for anyone to 'blindly' think about anything - almost every decision impacts the aircraft somewhere else. The complexity of modern fuel systems isn't driven by stupidity - but rather by necessity.
Best regards as ever to those fixing the tough problems,
Engines
Thanks for coming back. I'm not surprised that the F-117 had similar issues, as the key factors driving the issue were similar.
OAP, any decision can be 'dumb' - but using fuel as a heat sink is a sensible measure - it all depends how you implement it and schedule the thermal management system. Yes, of course the engine is generating big heat loads, but happily quite a bit of it gets flung out of the back of the aircraft. Thermal problems can (and do) arise all over highly integrated aircraft, in places such as flying controls and even antenna installations.
In designing a combat aircraft, it's rare for anyone to 'blindly' think about anything - almost every decision impacts the aircraft somewhere else. The complexity of modern fuel systems isn't driven by stupidity - but rather by necessity.
Best regards as ever to those fixing the tough problems,
Engines
Last edited by Engines; 4th Apr 2017 at 07:25.
Before the wretched thing was put out of its misery, some AEW3 planner turned up from Waddo to talk to our squadron war planning team about the offload requirement needed to keep the AEW3 supplied with enough fuel to keep it cool...
He seemed to think that each AEW3 would be allocated its own VC10K3 - of which we had but 4. We pointed out that this was nonsense, because the AEW3 orbit points were a long way from the tanker towlines, which were positioned to meet the AD fighter CAP needs.
I don't recall the offload quantity needed to keep the AEW3 satisfied, but it was huge. When I asked whether the E-3 would need the same, our visitor went rather quiet....
The only real difficulty tanker crews face in supporting fast jets at sea is the risk of the wretched fish heads shooting you down, despite all the identification procedures being carried out correctly. If the Navy's performance on JMCs was anything to go by, there wouldn't be any AAR after about Day 2 of any war. Not that their ships were ever where they were supposed to have been, according to the miles of signals they'd sent!
He seemed to think that each AEW3 would be allocated its own VC10K3 - of which we had but 4. We pointed out that this was nonsense, because the AEW3 orbit points were a long way from the tanker towlines, which were positioned to meet the AD fighter CAP needs.
I don't recall the offload quantity needed to keep the AEW3 satisfied, but it was huge. When I asked whether the E-3 would need the same, our visitor went rather quiet....
The only real difficulty tanker crews face in supporting fast jets at sea is the risk of the wretched fish heads shooting you down, despite all the identification procedures being carried out correctly. If the Navy's performance on JMCs was anything to go by, there wouldn't be any AAR after about Day 2 of any war. Not that their ships were ever where they were supposed to have been, according to the miles of signals they'd sent!
Engines,
thank you for not reading and understanding my post, then retelling me! BTW, I also understand design compromise. However, I tend to think that the use of fuel as a heatsink has not been optimal in many designs. The worst I have actually flown required 10% internal tankage min (shutdown) fuel, the best I have flown could be run till tanks dry! 
OAP
thank you for not reading and understanding my post, then retelling me!
BTW, I also understand design compromise. However, I tend to think that the use of fuel as a heatsink has not been optimal in many designs. The worst I have actually flown required 10% internal tankage min (shutdown) fuel, the best I have flown could be run till tanks dry! OAP
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OAP, there are few (if any) alternatives for managing heat and heat dissipation in stealth aircraft. By design they are pretty tightly closed up. Heat exchanger inlets are difficult to design without compromising the stealth needs - as always, the design is a balance on weighted characteristics.
Engines is right though, the issues so widely publicised and spread regarding chilled fuel etc, were specific to test conditions. Yes there are fleet operating limits but are rarely approached. I'd mention Tornado engine ground operating time limits as a comparison here.
Engines is right though, the issues so widely publicised and spread regarding chilled fuel etc, were specific to test conditions. Yes there are fleet operating limits but are rarely approached. I'd mention Tornado engine ground operating time limits as a comparison here.
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OAP,
Sincere apologies for not getting the sense of your post right. I'll try to do better in future.
MSOCS made some good points on this issue, which is (unavoidably) complex. How 'bad' or how 'good' the design compromises are depend on many factors including sortie profiles, fuel tank layouts, and not least environmental conditions. The key thing to remember, in my view at least, is MSOCS' point that thermal management is even more difficult on low observable aircraft.
Best Regards as ever to all those posting
Engines
Sincere apologies for not getting the sense of your post right. I'll try to do better in future.
MSOCS made some good points on this issue, which is (unavoidably) complex. How 'bad' or how 'good' the design compromises are depend on many factors including sortie profiles, fuel tank layouts, and not least environmental conditions. The key thing to remember, in my view at least, is MSOCS' point that thermal management is even more difficult on low observable aircraft.
Best Regards as ever to all those posting
Engines
OAP, there are few (if any) alternatives for managing heat and heat dissipation in stealth aircraft. By design they are pretty tightly closed up. Heat exchanger inlets are difficult to design without compromising the stealth needs - as always, the design is a balance on weighted characteristics.
Engines is right though, the issues so widely publicised and spread regarding chilled fuel etc, were specific to test conditions. Yes there are fleet operating limits but are rarely approached. I'd mention Tornado engine ground operating time limits as a comparison here.
Engines is right though, the issues so widely publicised and spread regarding chilled fuel etc, were specific to test conditions. Yes there are fleet operating limits but are rarely approached. I'd mention Tornado engine ground operating time limits as a comparison here.
Unless the fuel can be utilised for cooling without limitations or compromising the min fuel state, other methods for cooling should be used. For instance, IMO it would be better to use an optimised consumable cooling medium other than fuel (if the fuel option implies limitations). Minimum fuel limitations for heat limits, require the lugging around of additional weight till shutdown. Whereas an optimised consumable cooling medium that is consumed by shutdown represents an increasingly positive bonus through the flight. OAP
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OAP, if the option for a separate cooling medium didn't add weight and complexity to an already weight-sensitive and complex jet, I'd totally agree with your thinking on F-35!
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So does F-35 JTO. That's kinda the root of this thread at the mo. Issue is, the heat exchanger inlets are massive radar reflectors so no-can-do for stealth.
How LM have ameliorated the issue is actually very, very smart. 😉
How LM have ameliorated the issue is actually very, very smart. 😉