Conformal Fuel Tanks – No Free Lunch

Military aircraft - Post cold war aircraft, including for example B-2, Gripen, F-18E/F Super Hornet, Rafale, and Typhoon.
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Corsair1963

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Unread post13 Jan 2022, 05:34

Conformal Fuel Tanks – No Free Lunch

Fighters burn a lot of gas…a lot…and quickly.

No matter how much fuel we start with, we always burn it and always want more. In legacy fighters, using underwing weapons stations to hang fuel tanks takes up where bombs or missiles could be hung, slows us down and hampers our maneuverability. That’s where Conformal Fuel Tanks (CFTs) come in. Putting fuel tanks flush mounted along the fuselage, reduces the drag penalty from those external fuel tanks, and increases range and endurance…almost for free it would seem. Except there is no free lunch.

Super Hornet Block III promised CFTs and we have seen the promo photos with the fuel tanks bolted on to a new Super Hornet test airplane. But something happened (https://www.forbes.com/sites/davidaxe/2 ... ailed/amp/) and we have to wonder, how did Boeing screw this up? CFTs were to be a game changer, at least for a test pilot like me. All of a sudden, the Super Hornet would have the range capability closer to the F-35 and, for anyone in Canada and the US Navy, the reach of the Super Hornet would increase significantly. One could then argue that with CFTs and the promised improvements of avionics capabilities, certainly in the Canadian context, Super Hornet would be ‘Good Enough.’ CFTs would really help the fuel calculations to fly the distances needed from the Main Operating Bases (Cold Lake or Bagotville) to the Forward Operating Bases (Inuvik and Iqaluit), with extra fuel for a weather diversion if needed. Loading missiles on the weapons stations that were previously taken by external fuel tanks increases offensive capability that will matter in defense of the arctic and the potential of a Russian attack. Without CFTs, the Super Hornet is only marginally better than legacy CF-18 Hornets which never had enough fuel, ever.

So how did Boeing mess up this opportunity? Was there just not enough time to satisfy the US Navy’s requirements?

Read more at: https://billieflynn.com/conformal-fuel- ... ree-lunch/
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35_aoa

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Unread post13 Jan 2022, 07:47

Good article, thanks for posting. The loss of this upgrade was unfortunate, as the author points out. Block III is about a lot more than the CFTs (though they were maybe the most visually significant), but they would have been real nice to have. I'd say this is pretty on the money.
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Corsair1963

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Unread post13 Jan 2022, 08:11

35_aoa wrote:Good article, thanks for posting. The loss of this upgrade was unfortunate, as the author points out. Block III is about a lot more than the CFTs (though they were maybe the most visually significant), but they would have been real nice to have. I'd say this is pretty on the money.



Range is critical, especially within the Indo-Pacific.

Instead of buying more Super Hornet Block III's. We should be buying additional F-35C's!
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35_aoa

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Unread post13 Jan 2022, 09:32

Corsair1963 wrote:Range is critical, especially within the Indo-Pacific.

Instead of buying more Super Hornet Block III's. We should be buying additional F-35C's!


No argument there my friend. Range is important anywhere, even when we were trucking those hogs on 8 hr missions into AFG

- sent from my time machine where I was in the FBO waiting to get gas on leg 3 of 4 trying to get from Oceana to Fallon around a midwest storm front and 120+ knot winds aloft while carrying CATM HARM, CATM AIM-120, and the dumb 4 deg canted inboard pylons and turning dinosaurs into noise at incomprehensible levels
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Unread post13 Jan 2022, 10:18

35_aoa wrote:
Corsair1963 wrote:Range is critical, especially within the Indo-Pacific.

Instead of buying more Super Hornet Block III's. We should be buying additional F-35C's!


No argument there my friend. Range is important anywhere, even when we were trucking those hogs on 8 hr missions into AFG

- sent from my time machine where I was in the FBO waiting to get gas on leg 3 of 4 trying to get from Oceana to Fallon around a midwest storm front and 120+ knot winds aloft while carrying CATM HARM, CATM AIM-120, and the dumb 4 deg canted inboard pylons and turning dinosaurs into noise at incomprehensible levels



Sadly, the loss of the CFT's on the Super Hornet Blk III's was a big blow. As the USN was counting on it to bridge the gap until enough F-35C's could come online....
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quicksilver

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Unread post13 Jan 2022, 16:39

“As the USN was counting on it to bridge the gap until enough F-35C's could come online.”

The notional USN F-35C procurement objective has been ~260-275 jets. Block III Supers were/are the bridge to F/A-XX.
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35_aoa

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Unread post13 Jan 2022, 19:48

quicksilver wrote:The notional USN F-35C procurement objective has been ~260-275 jets. Block III Supers were/are the bridge to F/A-XX.


True statement, and not all Super Hornets are getting the B3 upgrade either, so the Block II will be part of that bridge as well.
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Unread post13 Jan 2022, 20:25

Vietnam veteran (70th Combat Engineer Battalion)(AnKhe & Pleiku) 1967
Retired from Chrysler Engineering
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mixelflick

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Unread post14 Jan 2022, 19:28

Personally, I thank God every night for the SH/CFT debacle. Why? Two reasons...

1.) It accelerates the day when I can finally look up and see no Hornets/Super Hornets/Super-Duper Hornets still flying and..
2.) We'll wind up buying more F-35C's OR even better, NGAD jets.

Win-win all around..
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Unread post30 Jan 2022, 05:00

The CFTs on the Super Bug were not just a way to extend range. Even though they carried less fuel than the EFTs they were supposed to replace, their reduced drag relative to them would supposedly compensate for that. In fact, for a while it was even claimed that the changed airflow over them improved handling and that a Super Hornet with empty CFTs had a slight range advantage over a clean Super H.

One of the other big reasons USN was interested in CFTs was not an increase in range. Everyone is looking for ways to carry more ordnance. CFTs offered the possibility of maintaining existing range while freeing up two pylons to carry weapons.

Looks like it didn't work out. Regardless of whether they actually work, apparently CFTs can't take the stresses involved with catapult launches and arrested landings (without a lot of structural work and money), so the Navy dropped them from the Block III upgrade. A possible confirmation is that Boeing is still offering them to potential export customers.

You know, CFTs have been proposed for lots of fighters, but the only a/c to actually successfully employ them is the Viper.
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sprstdlyscottsmn

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Unread post30 Jan 2022, 13:51

Mudhen?
"Spurts"

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aaam

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Unread post30 Jan 2022, 20:15

sprstdlyscottsmn wrote:Mudhen?


Excellent correction; I should have been more clear and referred to the CFTs that are a new added capability to existing designs. F-15 was conceived as being able to accept CFTs from the start, originally part of the "FAST (Fuel And Sensor Tactical) Packs" option.

F-15C entered service with CFT capability activated and supposedly this could even be retrofitted to F-15A/Bs. Israel has been using them for decades on their Baz version of the F-15.
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weasel1962

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Unread post30 Jan 2022, 23:25

May be surprising how tanks have evolved thru the years.

https://en.m.wikipedia.org/wiki/Conformal_fuel_tank
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aaam

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Unread post31 Jan 2022, 01:01

weasel1962 wrote:May be surprising how tanks have evolved thru the years.

https://en.m.wikipedia.org/wiki/Conformal_fuel_tank

Interesting...I hadn't realized that the MiG-29SMT with CFTs was actually operational. For the other aircraft, aren't those just paper proposals or test-only installations?
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weasel1962

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Unread post31 Jan 2022, 03:19

What caught my eye was the BAC 167 strikemasters. I remember the days when those used to fly in these parts where I'm at. Interesting how they termed the wing tip tanks as "conformal".
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