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Author Topic: Navy may add conformal fuel tanks to F/A-18E/F  (Read 20745 times)

Offline Triton

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #15 on: April 19, 2013, 02:49:25 pm »
Maybe the Boeing F-18 International will be Canada's replacement for their CF-18s paying for development costs. Then the United States Navy can go ahead an acquire these notional F-18E/F Block III Super Hornet aircraft.

Offline Sundog

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #16 on: April 19, 2013, 04:47:50 pm »

there is the added weight of fuel issue though, which might cut into what the fighter can carry..
plus the weight distribution would change, so agility and such will change.

so there are some issues that would need some extra study to pin down the effects.

Actually, the weight distribution shouldn't change, since the fuel is added very close to the C.G. and it really shouldn't impact what the fighter can carry, since it already has a robust landing gear due to the carrier requirements. But there is a chance that the gear would need some strengthening due to the increased load, which would also increase weight. However, I haven't seen it mentioned, but you do bring up a valid concern. I would argue that apparently Boeing thinks the pluses out weigh the minuses, or they wouldn't be offering it.

Offline sferrin

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #17 on: April 19, 2013, 07:45:09 pm »
I think its going to be done eventually anyway (if no one else jumps in to make it happen before the USN has to pony up the cash in a couple years). an SH with more range is a good thing, an F-35C is also a good thing:

They almost have to if they want to keep it relevant for more than tanking.  Even if the F-35C progresses swimmingly the last thing they want is half their air wing grounded if enemy air is present.
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Offline Triton

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #18 on: May 22, 2013, 12:09:15 pm »
Photos of Boeing F-18 Super Hornet CFT and weapons pod mockup at St. Louis, Mo.

Source:
http://www.flightglobal.com/blogs/the-dewline/2013/05/fa-18f-cft-weapons-pod-mockup.html
« Last Edit: May 22, 2013, 12:12:15 pm by Triton »

Offline Sundog

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #19 on: May 22, 2013, 06:18:50 pm »
Just for reference, for those who didn't read the article, the plane that is going to fly this year is just testing the aerodynamics. The CFT's and external weapons pylon will just be representative shapes, not functioning pieces of equipment.

They also state that carrying the the external weapons bay will have about the same drag as carrying the stores within in it in a normal external fashion. I wonder if they mean that just in terms of form and interference drag, or if they are also including the minor increase in induced drag due to the increased weight? Or at least I'm assuming a functioning weapons pod would weigh more than the external pylons to carry the same load, due to the weight of the doors and launch mechanisms that would be within the pod.

Offline Pioneer

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #20 on: May 23, 2013, 06:06:50 pm »
Can I ask why they would not simply eliminate the pylon/hardpoint between the fuselage and weapons pod all together - aka make it flush!
 
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Offline aim9xray

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #21 on: May 23, 2013, 09:41:44 pm »
Conformal carriage would force the usable volume in the pod to be reduced due to the cutout that would be needed to clear the nose landing gear actuator.  If the pod was shortened to clear the actuator, AMRAAMs probably could not be carried. I assume that there would also be aerodynamic issues with a conformal pod and the flow field inboard of the intakes.

Offline flateric

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #22 on: May 24, 2013, 07:43:16 am »

Conformal carriage would force the usable volume in the pod to be reduced due to the cutout that would be needed to clear the nose landing gear actuator. If the pod was shortened to clear the actuator, AMRAAMs probably could not be carried.
"if" and "probably" doesn't count, I wonder if you have seen pod size and operation sequence at all?
Phantom Work guys I think know how to handle aerodynamics.
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Offline TaiidanTomcat

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #23 on: May 24, 2013, 08:43:44 am »
Quote
"if" and "probably" doesn't count, I wonder if you have seen pod size and operation sequence at all?

I know I haven't.  Mock-up is a Mock -up as far as I know.
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Offline flateric

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #24 on: May 24, 2013, 09:43:45 am »
Almost all aircraft projects at certain time were just mock-ups, so what is your point?
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Offline Bill Walker

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #25 on: May 24, 2013, 10:33:13 am »
The pod opening in the artwork clearly extends further forward than the nose gear drag strut door.  No if or probably about it. ;)

If the AMRAAM size opening was moved aft to clear the door, there would be a c.g. shift - assuming the pod is still long enough for an AMRAAM.  The rear end of the pod is limited by landing gear geometry (definitely) and aerodynamics (probably).

I'm sure the Phantom Works guys understand the aerodynamics around both pylon mounted pods and conformal pods.  Maybe that is part of why they chose a pylon mount.
« Last Edit: May 24, 2013, 10:35:34 am by Bill Walker »
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Offline flateric

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #26 on: May 24, 2013, 01:15:50 pm »

The pod opening in the artwork clearly extends further forward than the nose gear drag strut door.  No if or probably about it. ;)


I'm not sure again if you are correct, as isometry view may be playing tricks with your eye.
Second, I hope, you don't think Boeing guys are idiots showing IRM presentations to worldwide where pod intersects with NLG strut?
« Last Edit: May 24, 2013, 01:23:16 pm by flateric »
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Offline Bill Walker

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #27 on: May 25, 2013, 12:55:19 am »
I'm not sure again if you are correct, as isometry view may be playing tricks with your eye.
No, the leading edge of the pod is well forward of the trailing edge of the strut fairing door, look at the side views.  I'm just backing up aim9xray's argument that the shape and position of the front of the pod is driven (at least in part) by leaving clearance for the nose gear strut.

Quote
Second, I hope, you don't think Boeing guys are idiots showing IRM presentations to worldwide where pod intersects with NLG strut?
No, the pod shown is in line with BUT BELOW the volume swept by the nose gear strut.  The pictures do not show, and I never said, that the pod volume and the swept volume of the nose gear strut intersect.  As aim9xray pointed out, raising the pod from its current position to be conformal WOULD intersect this strut volume - leading to complications like extra doors and door sequencing on the pod, and a loss of usable internal volume within the pod.
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Offline fightingirish

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #28 on: May 25, 2013, 05:16:05 am »
In the latest AW&ST magazine 27 May 2013 there is an article about the future Boeing F/A-18 Super Hornet. A CGI provided by Boeing shows an production F/A-18F with conformal fuel tanks and an enclosed weapons pod as shown in former pictures.
But the image also shows a new coating/camouflage, which is darker and like on F-15E. On the side is written "Advanced Super Hornet".
 
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Offline mithril

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Re: Navy may add conformal fuel tanks to F/A-18E/F
« Reply #29 on: May 25, 2013, 12:10:23 pm »

there is the added weight of fuel issue though, which might cut into what the fighter can carry..
plus the weight distribution would change, so agility and such will change.

so there are some issues that would need some extra study to pin down the effects.

Actually, the weight distribution shouldn't change, since the fuel is added very close to the C.G. and it really shouldn't impact what the fighter can carry, since it already has a robust landing gear due to the carrier requirements. But there is a chance that the gear would need some strengthening due to the increased load, which would also increase weight. However, I haven't seen it mentioned, but you do bring up a valid concern. I would argue that apparently Boeing thinks the pluses out weigh the minuses, or they wouldn't be offering it.

actually i was thinking more in terms of possible muntions load being reduced due to carrying extra weight of fuel. after all, a fighter can only carry so much in terms of extra weight, and every pound of extra fuel is a pound that can't be used for carrying missiles, bombs, or other gear. yet one of the Pro's of overwing/conformal tanks is freeing up hardpoints on the wings to carry munitions instead of external tanks. presumably the engineers would design the conformal tanks so they don't cut into the useful weapons load too much, but there would definitely be some trade offs involved.