F-35 internal fuel, range

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spazsinbad

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Unread post07 Jan 2020, 12:26

I find it 'faskinatin' not that there is endless B/S about Soviet Aircraft on a thread about 'F-35 internal fuel, range'. Why.
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ricnunes

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Unread post07 Jan 2020, 12:33

weasel1962 wrote:However, doesn't change the fact that the su-27 was designed as a long-ranged fighter, not a point defence fighter like the Migs.


Yes, indeed.
I agree and echo mixelflick's words that the Russian design philosophy has apparently shifted in the relatively recent past (I would say since the 1980's) with the Su-27 family that you mentioned and also with the Mig-31 and apparently and more recently with the Su-57.
Anyway, the point of my previous post was to correct the "always liked" part of the "Russians have always liked long ranged planes" sentence.
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Unread post07 Jan 2020, 12:49

And it seems that range has become more important than ever recently even in US. Fighter aircraft are getting more and more CFTs and F-35 was specifically designed to carry a huge amount of internal fuel with really high fuel fraction.
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ricnunes

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Unread post07 Jan 2020, 15:29

hornetfinn wrote:And it seems that range has become more important than ever recently even in US. Fighter aircraft are getting more and more CFTs and F-35 was specifically designed to carry a huge amount of internal fuel with really high fuel fraction.


Yes, I agree.

In the case of the US/West, I'm pretty sure the reasons are rather obvious. Air superiority together with Tactical, Interdiction and Strategical Air-to-Ground strikes is the cornerstone of US/Western/NATO strategy to overcome any enemy and as such having longer range and as such inevitably associated with more fuel is of paramount importance to achieve this.

Regarding the Russian (or even Eastern) perspective, I wonder if the Mig-29's colossal failure - doesn't matter which excuse a fan of this plane may come up with, there's no other wording to describe the Mig-29's real combat performance! - which was even a failure against the Su-27 (during the Ethiopia-Eritrea War of 2000) played a significant role in Russia's decision to go with bigger and longer ranged aircraft (Su-27 family and later the Su-57)??

Of course that short range doesn't fully excuse the Mig-29 poor record but I would say that "short range" would likely be among the Mig-29's top three (3) or so shortcomings.
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Unread post07 Jan 2020, 18:35

weasel1962 wrote:Factually at least 28% more thrust than the F-35. Do kindly share your drag coefficient "sauces" to demonstrate...


There's been discussions of how well Flanker and F-35 accelerations compare to other aircraft on these forums. IIRC, the F-35A compares well with F-16C, which puts it well ahead of the Flanker.

And there's this thread: viewtopic.php?f=55&t=52510

Flanker accelerating worse than F-35 means it has less excess thrust over drag, despite possessing greater thrust. This means the Flanker has significantly more drag than the F-35.
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Unread post07 Jan 2020, 19:09

knowan wrote:
weasel1962 wrote:Factually at least 28% more thrust than the F-35. Do kindly share your drag coefficient "sauces" to demonstrate...


There's been discussions of how well Flanker and F-35 accelerations compare to other aircraft on these forums. IIRC, the F-35A compares well with F-16C, which puts it well ahead of the Flanker.

And there's this thread: viewtopic.php?f=55&t=52510

Flanker accelerating worse than F-35 means it has less excess thrust over drag, despite possessing greater thrust. This means the Flanker has significantly more drag than the F-35.


Well... it's larger, so all things being equal, yeah, it's going to have more drag. Or were you meaning to state that the Flanker has a higher zero lift drag coefficient than the F-35?
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Unread post07 Jan 2020, 22:24

steve2267 wrote:
Well... it's larger, so all things being equal, yeah, it's going to have more drag. Or were you meaning to state that the Flanker has a higher zero lift drag coefficient than the F-35?


They could have the exact same coefficient and the Flanker would have 40+% more actual zero lift drag.
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Unread post08 Jan 2020, 01:06

ricnunes wrote:
weasel1962 wrote:However, doesn't change the fact that the su-27 was designed as a long-ranged fighter, not a point defence fighter like the Migs.


Yes, indeed.
I agree and echo mixelflick's words that the Russian design philosophy has apparently shifted in the relatively recent past (I would say since the 1980's) with the Su-27 family that you mentioned and also with the Mig-31 and apparently and more recently with the Su-57.
Anyway, the point of my previous post was to correct the "always liked" part of the "Russians have always liked long ranged planes" sentence.


That part I maintain what I said. Long ranged interception does not stem from the Su-27. You can trace the Soviet roots down to the Yak-25 thru Su-15 and the split between PVO (long ranged interception) and Frontal aviation. Long ranged interception requirements arose from the start of the cold war due to the threat of nuke-armed bombers and the Yak-25 (or Yak-120) was developed from 1951 to fill that need. Before that, one might even point to the Yak-9D.

Agree in part that the Su-27 inclusion into frontal aviation may have changed that segment from just point defense but PVO has existed since way before that.
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Unread post08 Jan 2020, 01:17

steve2267 wrote:
knowan wrote:
weasel1962 wrote:Factually at least 28% more thrust than the F-35. Do kindly share your drag coefficient "sauces" to demonstrate...


There's been discussions of how well Flanker and F-35 accelerations compare to other aircraft on these forums. IIRC, the F-35A compares well with F-16C, which puts it well ahead of the Flanker.

And there's this thread: viewtopic.php?f=55&t=52510

Flanker accelerating worse than F-35 means it has less excess thrust over drag, despite possessing greater thrust. This means the Flanker has significantly more drag than the F-35.


Well... it's larger, so all things being equal, yeah, it's going to have more drag. Or were you meaning to state that the Flanker has a higher zero lift drag coefficient than the F-35?


I'm not sure whether the issue is being conflated. One would naturally expect lower acceleration due to wind flow for a swept wing design like the su-27 at lower speeds. Lower speed = lower airflow. However, higher thrust is therefore precisely used to offset/compensate for this. That's the design. At higher speeds, the drag factor is offset. I think it would be erroneous to interpret that to mean the Su-27 has a higher drag at all speeds/altitude.

The trapezoidal design like the F-35 doesn't have that problem but the offset is, in theory, a higher wing loading that affects the lift coefficient. That was also the initial criticism of the F-35 but I think pilot experience shows otherwise. At higher speeds, the drag difference between the 2 is imho unlikely to be materially advantages for the F-35, unless the Su-27 carries significant external stores to create the additional drag. I haven't read anything to suggest that is an incorrect understanding but I never studied aeronautical engineering so I'd gladly defer to the experts.
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Unread post08 Jan 2020, 05:01

For aircraft range, subsonic cruise and drag are most relevant, and the Flanker does appear to be inferior to F-35 in that flight regime.

While I did not mention subsonic flight in regards to drag previously, it was what I was talking about.
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Unread post08 Jan 2020, 08:33

knowan wrote:For aircraft range, subsonic cruise and drag are most relevant, and the Flanker does appear to be inferior to F-35 in that flight regime.

While I did not mention subsonic flight in regards to drag previously, it was what I was talking about.


Which again is not conclusive because that also depends on air density i.e. altitude. drag increases the lower one goes, hence the most efficient cruise ranges are often at higher altitudes which again may not suggest a significant difference throughout the entire subsonic envelope. That's also why the Su-30 brochure states a 3000km cruise range and a 1270km range at low altitude. I would not be surprised if the f-35 can go beyond 1270km range flying low but the standard cruise range should not be very far from that of the Su-30mk2.
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Unread post08 Jan 2020, 09:10

weasel1962 wrote:Which again is not conclusive because that also depends on air density i.e. altitude. drag increases the lower one goes, hence the most efficient cruise ranges are often at higher altitudes which again may not suggest a significant difference throughout the entire subsonic envelope. That's also why the Su-30 brochure states a 3000km cruise range and a 1270km range at low altitude. I would not be surprised if the f-35 can go beyond 1270km range flying low but the standard cruise range should not be very far from that of the Su-30mk2.


Altitude won't favour the Flanker; drag will decrease by the same proportional rate for each aircraft as they go higher, because it isn't the aircraft that is changing but atmospheric density.

As sprst said, even assuming same coefficient, the Flanker has at least 40% more drag; that's more than enough to result in lesser range despite the Su-27/30 possessing ~15% more fuel.
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Unread post08 Jan 2020, 12:27

spazsinbad wrote:I find it 'faskinatin' not that there is endless B/S about Soviet Aircraft on a thread about 'F-35 internal fuel, range'. Why.


I agree that it has gone quite off-topic but I think the original idea was to compare F-35 range with one of the longest legged and largest 4th gen fighters. And it does compare very favourably there and also to all other current fighters. I think if we compare combat loaded F-35A to combat loaded Su-30 for example, F-35A is going to have superior range not to mention all other advantages it has.
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Unread post08 Jan 2020, 15:43

ricnunes wrote:
hornetfinn wrote:And it seems that range has become more important than ever recently even in US. Fighter aircraft are getting more and more CFTs and F-35 was specifically designed to carry a huge amount of internal fuel with really high fuel fraction.


Yes, I agree.

In the case of the US/West, I'm pretty sure the reasons are rather obvious. Air superiority together with Tactical, Interdiction and Strategical Air-to-Ground strikes is the cornerstone of US/Western/NATO strategy to overcome any enemy and as such having longer range and as such inevitably associated with more fuel is of paramount importance to achieve this.

Regarding the Russian (or even Eastern) perspective, I wonder if the Mig-29's colossal failure - doesn't matter which excuse a fan of this plane may come up with, there's no other wording to describe the Mig-29's real combat performance! - which was even a failure against the Su-27 (during the Ethiopia-Eritrea War of 2000) played a significant role in Russia's decision to go with bigger and longer ranged aircraft (Su-27 family and later the Su-57)??

Of course that short range doesn't fully excuse the Mig-29 poor record but I would say that "short range" would likely be among the Mig-29's top three (3) or so shortcomings.


The range issue may also be a consequence of peripheral factors. Meaning USAF has an enormous fleet of tankers, while Russia doesn't. And while this has served the U.S. well in the past, dependency on tankers is a growing issue - particularly with Chinese/Russian ultra long range AAM's entering service. The F-35 will go a long, long way toward reducing that tanker dependency. By any measure, it's a dramatic improvement over legacy fighters (with the possible exception of the F-15E).

I share your opinion of the Mig-29, and agree wholeheartedly it couldn't have failed in a more spectacular way. The Iraqi's had some of their best pilots flying them, but it didn't matter. Reduced to spare parts/teeth/eyeballs. Post Gulf War 1 findings of the Iraqi air force found that the Mig-25 was perhaps their most successful aircraft. They were most disappointed in their Mig-23's (which was more or less expected), and likewise their Mig-29's (which wasn't)

In the Serbian conflict, they lost 6 Mig-29's there; 2 to F-15's and 2 to F-16's. The Iranians? They found the F-14 superior to their Mig-29's in almost every way, and consequently only bought a limited number.

In summary, the Mig-29 continued the tradition of Russian fighter aircraft falling victim to their US built counterparts. Full combat win/loss record appears below. With the exception of some action in Cuba*, it's rather damning...

MiG-29 6-18-1

Lebanon War 1982-2000 (Syria) 0-2-0
Gulf War (Iraq) 0-5-0
Transnistria War (Moldova, Russia) 0-0-0
Brothers in Rescue incident* (Cuba) 2-0-0
Slovenian War (Yugoslavia) 0-0-0
Croatian War (Yugoslavia) 0-0-0
Bosnia (Serbia) 0-0-0
Kosovo (Serbia) 0-6-0
Kargil War (India) 0-0-0
Ethiopian-Eritrean War (Eritrea) 3-5-0
Georgian border violation 2008 (Russia) 1-0-0
Darfur War (Sudan) 0-0-1

* It did shoot down 2 Cessna Skymasters... :)
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Unread post08 Jan 2020, 15:58

Salute!

The Finn has it right. However, without some war stories from Flanker flyers, we're speculating too much.

I think the original idea was to compare F-35 range with one of the longest legged and largest 4th gen fighters. And it does compare very favourably there and also to all other current fighters.


I would rather see Super Bug and Mudhen folks comment/compare.

Secondly, the big effect of altitude is the engine's performance. e.g. we cruised at 20K to 25K in the Sluf because the motor and drag combination was best for range there. And we were SLOW!!! We could gradually climb higher, but gained little miles per gallon. So from Korat to Hanoi we would get to 25K, then we started a full grunt descent about 100 miles out. The Viper motor was really great up at 30 - 35K, and if clean we could handle 40K slightly supersonic in mil for a minute or two, then tap burner and get back to 1.1M for another minute or two ( family model with centerline tank). I routinely demo'd this to students when coming back from Mountain Goat ( we flew "strange" field insturment approaches at SLC and the Goat)

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