pfcemWho said external tanks are heavier?
God. Physics. Gravity.
They’re usually lighter than the corresponding weight increase to accomodate the same amount of fuel internally.
Quite the oppisite. It takes comparatively little increase in external dimensions (resulting in comparatively little increase in weight/drag) to provide a significant increase in internal volume. Plus, BECAUSE INTERNAL FUEL CARRIAGE IS MORE EFFICIENT THAT EXTERNAL FUEL CARRIAGE, you don’t need as much increased internal fuel in order to obtain the same range vs external fuel carriage.
And what if no external tanks are needed to reach the desired range ?
Then you don’t have a problem because you have enough internal fuel. 🙂 And you are carrying all the fuel you need in the most efficient way possible. And last but not least, when you don’t need to you don’t HAVE to carry a full load of fuel just becasue you have the capacity to do so…
In this case, a larger airframe is much less efficient.
Not nearly as much as you are implying though. Look at all the aircraft that in later varients have increased their internal fuel capacity…
So it all boils down to a tradeoff that is much less obvious than what you’re implying.
Quite the contrary, the drag/weight/performance penalty of external fuel carriage is quite obvious. The drag/weight/performance penalty internal fuel carriage is less so…
Large aircrafts are good (efficient) for long range only. Other than that, smaller airframes are better suited.
No, aircraft no matter what their size are most good (efficient) for obtaining a desired range when it carries as much (preferrably all) of the fuel required to obtain any given range internally.
pfcemYour idea about drag is limited to stay polite. Aerodynamic-behavior has nothing to do with simple logic. You may have realized, that all fighters and ETs are designed to have the smallest frontal size or frontal drag, when the related length did not matter in a similar way. Not going into two many details, today all ETs are purpose built and designed to get the most from that. There are special subsonic as well as supersonic ETs or some compromises for a wider speed range.
MOST (not all) ETs are purpose built & designed to minimize the significant drag/weight/performance penalty they create.
CFTs are a compromise between the lesser drag/weight/performance penalty of internal fuel & the greater drag/weight/performance penalty of external fuel on aircraft BECAUSE IT HAS BEEN FOUND THAT THEY DO NOT CARRY ENOUGH INTERNAL FUEL FOR MOST ALL THE MISSIONS THEY FLY & in order to minimize the drag/weight/performance penalty of external fuel (thus removing the NEED to pretty much always carry comparatively inefficient external drop tanks) do so in such a way as to carry ‘external’ fuel but in a way more closely to that of internal fuel BECAUSE IT IS MORE EFFICIENT.
The modern ETs are so refined in the meanwhile, that they could be kept throughout a mission without a real penalty from that and you will seldom see a modern fighter without a ET at all.
Thats right, you will seldom see a modern fighter without a ET because they do not carry enough internal fuel & thus HAVE to carry ADDITTIONAL fuel externally.
So I ask again, why is it that later varients of so many combat aircraft are increasing their INTERNAL fuel capacity (or going with the compromise of CFTs) instead of more/bigger external tanks. AND how much heavier/draggier are they due to said increased fuel capacity?
pfcemAnd because of the added weight and drag, you’d need a more powerful engine and yet more fuel to feed this bigger engine so that range requirements are met.
Not as much as you are implying & further is negated by the inefficiency of external tanks.
The tradeoff is definitely not obvious if maximum range is not the primary concern.
No matter what the desired range is, carrying enough fuel internally to do so is more effeicient that HAVING to carry heavier/draggier external fuel & tanks.
pfcemLet me summarise all this lift/drag internal/external fuel stuff.
Carrying more fuel internally increases drag, both because of the extra weight of the fuel needing more lift & the extra drag of the larger fueselage needed to carry the fuel. There will also be some extra structural weight, increasing drag a little more.
Carrying fuel externally also increases drag. The weight-induced extra drag is about the same, but the drag of external tanks is even more than the fatter fuselage needed to carry it internally. It is therefore less efficient than carrying all fuel internally, for the same fuel load.
However, once external tanks are empty, they can be dropped. If this is done, then the drag of the aircraft carrying external tanks drops considerably. An aircraft carrying all its fuel internally still has the extra structural weight & fat fuselage, so is now at a disadvantage in fuel efficiency.
In real combat operations, external tanks will be dropped when empty.
Therefore, one can not assume that internal fuel carriage is more efficient overall than external. One has to perform careful calculations to discover whether it is or not, for any given mission profile.
Similar considerations apply to the fuel efficiency of internal & external carriage of weapons. An internal weapons bay has aerodynamic & structure weight penalties to offset against the drag of externally carried weapons.
The only indisputable advantage of internal carriage is in radar cross section.
Is that a reasonable summation?
How much heavier/draggier is the Griphen NG vs the Griphen C & how much is due to the 41% increase in internal fuel capacity?
How much heavier/draggier is the Mig-29M vs the Mig-29C & how much is due to the 39% increase in internal fuel capacity?
How much heavier/draggier are the F-15, F-16, Rafale & Typhoon with CFTs vs the same without CFTs & how much is due to the increase in essentially internal fuel capacity?
Sorry but people are PURPOSEFULLY/IGNORANTLY exaggerating the weight/drag of internal fuel & PURPOSEFULLY/IGNORANTLY downplaying the weight/drag of external fuel.
pfcemF-35 is a strike aircraft that’s sure, so what about it’s interception capability? It look quite important since most F-35 buyers will never heve F-22?
No, the F-35 is a strike FIGHTER. It is every bit (AND MORE) a fighter as the F-16, F/A-18, Rafale, Mig-29, et cetera are.
Interception capability? About as close as you can get to the F-35 is to load up an F/A-18E/F Block II with a pair of external drop tanks & 4-6 AAMs but somehow magically give that COMBAT LOADED F/A-18E/F the acceleration & agility of a CLEAN F-16 Block 50…
Let’s check that scenario:
A group of Su-35Bm is advancing Norweigan airspace flying at 52000 feet with cruise speed 1.1Mach. Norweigans detects Su-35s 350km faraway from the F-35 base. F-35 equiped with 4 x AIM-120D and SU-35s carrying 6 long range 2 short range missile. And F-35s are scrambled to intercept them…
Question is can F-35 intercept Su-35s in that altitude and while it has 1.1 Mach?
Absolutely. And quite likely the Su-35s would not even know the F-35s were in the air (short of some real-time intel informing them of such or some intermittent RWR blips) until their aircraft started screaming “MULTIPLE AMRAAM CLOSING 12 O’CLOCK” (not say the Su-35s would LITERALLY be talking but in the way they communicate such things to the pilots they would be).
pfcemOK, although I hate it when other people do this I am going to make a comment here ‘harking’ back to a previous discussion…
Why is it that in the desire to increase the range of the Gripen, Saab increase the internal fuel capacity rather than use more/bigger external fuel tanks? That is a wopping 42% increase (2,100 lbs) in internal fuel capacity.
***
And as someone is so keen to point out as if it is a bad thing, the F-35 is aerodynamically optimized for the flight profile in which it will spend the VAST majority of time…
As for the Gripen NG, yes it is a small/light aircraft but that just means that it is MORE effected by external stores than larger/heavier aircraft. You are fooling yourself if you believe it out ranges the F-35. The F-35 really ISN’T that big, generally larger engines are more efficient than smaller ones & an aicraft that is twice as heavy does not require twice as much fuel to travel the same distance…
pfcemIf you cant under stands the basics, please read the rangedata…
F-35B 2,000 km
F-35C 3,000 km
http://www.globalsecurity.org/military/systems/aircraft/f-35-specs.htm
Gripen NG
2500km internal
4075km externalhttp://www.jsfnieuws.nl/wp-content/NLGRIPENPRESSBRIEFAug08.pdf
LOL
pfcemF-22.
I know it hasn’t happened yet but all indications are STILL that we will not get the 381 MINIMUM needed (which STILL requires 186 F-15C remain combat operational beyond 2025 in order to maintain adequite force levels) much less enough to completely replace the F-15 as intended.
PATHETIC given that 20 F-22s a year represents <0.1% of the yearly US budget, <0.6% of the yearly base defense budget (not including supplimental war spending) or ~2% of the yearly USAF budget. Less than $30 billion over 10 years.
pfcem1. There are plenty of people who do not want their tax dollars spent on insanely costly military Hardware that gets used once a decade, and that one is more of a token contribution. If you are so much against paying for some poor sods medical treatment so he can live.. how about introducing new tax system where citizen fill on their returns form where they want their tax dollars to go .. something tells me CIA/NSA and DoD budgets would not be as big, while Sicence, Medicine and Social projects would benefit.
That military hardware benfits the ENTIRE nation & is used every single day.
Plus nataional defense in a Constitutional obligation of the US government, making the top 25% of wage earners pay the bills of bottom 50% is not.
2. Out of all “Western” nations USA has one of the largest national debts, as well as budget/trade deficits .. and while it is very true that economic crisis is hitting hard every developed economy in the world (and developing ) … difference is most other countries are accepting reality and curbing spending .. while you are still dreaming of spending trillions on shiny military equipment, you don’t really need or need so much of. You would need even less of it if you chose to tweak your foreign policy not to meddle your fingers into every **** fest on the planet. 😉
Out of all “Western” nations, the USA has THE largest national economy & its debt in comparision to its economy is LOWER than most of Western Europe.
Believe me PLENTY of us in the US are appalled at Obama’s “more spending is the answer” & TRILLION dollar deficits for years to come.
Funny how with TRILLION dollar deficits (spending money on things the government has NO Constitutional authority to) you think you are going to do ANYTHING by cutting tens of billions on defense…
pfcemSo why are you persisting with claims that USAF needs more F22 than they got.. i mean what do you know that Congress does not …
Because the USAF says it needs more than it (thus far) is getting. And unlike all the BS claims that the USAF can do with less, the USAF has actually looked at (& understands) how many it needs & has JUSTIFIED the number it came up with. The 183 is just how many was agreed to be funded through the end of the Bush Administration & has NOTHING IN ANY WAY to do with how many the USAF needs.
Even if the USAF gets the MINIMUM 381 F-22s it needs, it STILL needs to somehow keep 186 F-15C combat operational beyond 2025! Every F-22 LESS than 381 is AT LEAST 1-2 MORE F-15C that need to somehow be kept combat operational longer than already expected. And F-15s have been flight restricted for quite some time already because of their age. The NEWEST USAF F-15C was built in 1986!
The USAF is going to be lucky to get enough F-35s to replace its F-16s MUCH LESS replace F-15s that aren’t replaced by F-22 as well. So don’t give me that crap that the F-35 can do the F-22’s job.
pfcemBecause folks dont need medical treatments, when they can look at pretty pictures of B2s just sitting there at billon a pop for two decades and getting used twice. :diablo:
Of course people need medical treatments. That does not mean that I have to pay for it.
USA like its corporations which are failing left right and centre, is living beyond its means… adding to the existing 10 TRILION (good lord) deficit will only go so far before foreign partners relise US is basically printing more and more money with no backing value behind it… then we are in for disaster.
Perhaps you should look at the amount of debt other nations have vs the size of their economy…
Right not your new president has far more dire things to fix, than getting more insanely expensive military hardware , that is not needed and will spend its life just sitting there unused… unless ofcourse Obama like his predecesor plans to start wars on false pretenses.
:rolleyes:
pfcemAs F-22 Raptor is the benchmark as far as supercruise goes, I’ll add this rough time estimation at full dry thrust for comparison. Later info indicate a higher fuel burn for both of them, which would favor a smaller engine.
F22 Internal Fuel ~18448 lbs
(2 x F119)
55000 lbs Mil thrust @ 0.7 lb/lb.hr~0.48~29 minGRIPEN NG Internal fuel ~7100 lbs
(1xF414)
~15000 lbs Mil thrust @ 0,7 lb/lb.hr~0.68~41 minSummary:~Gripen NG +41% increase in time over F-22 Raptor.
Perhaps we should have a discussion as to what minute supercruise suddenly become operationally useful ? 🙂
The internal fuel capacity of the F-22 is 3082 gal/20,650 lbs (see Technical Order 00-105E-9).
By the definition of supercruise used to describe the F-22, the Gripen NG (nor the Typhoon, Rafale, F-35, et cetera) does not supercruise. 😉 The F-22’s “supersonic cruise” speed (assuming Mach 1.2 is correct for the Gripen NG) is 43% greater than the Gripen NG.
If the goal is to cruise supersonically for an EXTENDED period of time as opposed to the MUCH more common goal to cruise supersonically for given DISTANCE, the F-22 can simply SLOW to Mach 1.5 or even Mach 1.25…
pfcemGenerally it is only the ability to fly supersonic for prolonged time and distance, basically only limited by fuel. Some aircraft had supersonic cruise ability before.
“Supercruise” is more like a trademark than a fixed aeronautical term.
Exactly & to those who “coined the phase” (USAF/US DOD) ‘supercruise’ means cruising at >Mach 1.5 without afterburner, rather than the >Mach 1.0 others use to say “we can do it too“.
Important to keep in mind when the USAF/US DOD says the F-35 wasn’t designed to supercruise as supercruising was not one of its requirements.
pfcemWhat tank force ?? 59 M1s … you cant be really thinking that 59 tanks would make anything but token contribution to any involvement which would mandate “US support” in logistics.
You have it backwards. It is not US support of Australia but Australian support of the US.
Unless of course you think Australia will break out of its mold & become a major independent power with far reaching world-wide obligations/aspirations…
EITHER WAY, commonality with US forces is the key…
If the purpose of 59 M1s is to mantain our Tank force and capability (i still think we don’t need MBTs at all ) old leos were more than enough.
The purpose is to be able to work side-by-side with US tank forces with a significant degree of commonality.
If you are of the argument that if you are going to have such small amount, and might as well get the best there is, Challanger 2 would have made better option..
How?
and talk about crew protection.. id like to see M1 take hit from MILAN and keep fighting…
Every bit as well as a Challenger 2 or Leopard 2 can.
and … IT DOES NOT NEED GAS PIPELINE TO RUN. Turbines are meant for things that fly, or sail at best… not things that roll on ground. :p
:rolleyes:
pfcemWebster is your friend 😀
First day/days…makes no difference. It is idiotic to assume you will destroy an ENTIRE defense network in such a short time. And such that stealth is only useful/relevant during the opening stages of a conflict.
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