# Wing-tip drop tanks vs. 'regular' drop tanks?



## tomo pauk (Dec 21, 2013)

Wing-tip fuel tanks came in vogue post-ww2. Wonder whether someone might shed some light explaining both good and bad things, vs. the usual configuration used on ww2 aircraft?

MODERATORS, could you please move this into the 'Aviation' subforum - thanks


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## michaelmaltby (Dec 21, 2013)

I think FlyboyJ has covered much of this in various posts. Tip Tanks can _stabilize_ wing aerodynamics ..... if I understood him correctly.

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## silence (Dec 21, 2013)

and they look cool!


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## FLYBOYJ (Dec 21, 2013)

Moved it into post WW2.


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## davebender (Dec 22, 2013)

Probably need to reinforce wings if you are going to place several hundred pounds of fuel on the tips.


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## Capt. Vick (Dec 22, 2013)

I have heard that the P-80 was aerodynamically "cleaner" with tip tanks than without.


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## Glider (Dec 23, 2013)

Its a guess but I suspect the wing tip tank would have a similar impact as the winglets on modern airliners. The would reduce the induced drag resulting in a cleaner airflow.


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## iron man (Jan 11, 2014)

michaelmaltby said:


> I think FlyboyJ has covered much of this in various posts. Tip Tanks can _stabilize_ wing aerodynamics ..... if I understood him correctly.


Ahh. The good old "ERB" (End of Runway Bomber).

757 is a beauty, served with 434 in the late '70's. 

The BEST Thing about the CF-116 was the fact that it ATE UP HOURS at a cheap price per hour. I lived in Cold Lake during the '70's and was there during the CF-18 transition as well. Seen it all...and then some.

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## swampyankee (Jan 12, 2014)

davebender said:


> Probably need to reinforce wings if you are going to place several hundred pounds of fuel on the tips.



The tip tanks' weight is only a problem when the aircraft is on the ground. In flight, they will reduce the bending moment on the wings.

As to the aerodynamics, tip tanks may reduce the induced drag enough to offset their form drag. They probably did so on the F-80 and the USN's F9F Panther.


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## GrauGeist (Jan 12, 2014)

swampyankee said:


> The tip tanks' weight is only a problem when the aircraft is on the ground. In flight, they will reduce the bending moment on the wings.
> 
> As to the aerodynamics, tip tanks may reduce the induced drag enough to offset their form drag. They probably did so on the F-80 and the USN's F9F Panther.


And the F2H2 Banshee, if I remember right.


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## gjs238 (Jan 13, 2014)

Were there ever DROP wing tip tanks, or are they permanent?


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## gumbyk (Jan 13, 2014)

I'm not aware of any that were drop tanks. When they were empty, they'd almost surely improve efficiency of the wing, so there's not real point in dropping them.


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## FLYBOYJ (Jan 13, 2014)

swampyankee said:


> The tip tanks' weight is only a problem when the aircraft is on the ground. In flight, they will reduce the bending moment on the wings.



This would depend on the aircraft. I could tell you that tip tanks did not reduce the bending moment on the T-33 during certain speeds and flight attitudes..



gjs238 said:


> Were there ever DROP wing tip tanks, or are they permanent?



Again, depends on the aircraft.

There are pics and films of F-80s and F-84s dropping their tip tanks. The L29R and L39 have permanent tip tanks.


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## michaelmaltby (Jan 15, 2014)

Off topic but lovely photos ..... drop tanks into canoes in Viet Nam

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## iron man (Jan 15, 2014)

michaelmaltby said:


> Off topic but lovely photos ..... drop tanks into canoes in Viet Nam


<singing>
"Reduce, Re-use...Recycle aaand. Recover".
<singing off>

For those who don't get it...

(Old Canadian Government PSA spot from the late '70's CBC...)

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## gumbyk (Jan 15, 2014)

FLYBOYJ said:


> There are pics and films of F-80s and F-84s dropping their tip tanks. The L29R and L39 have permanent tip tanks.



I stand corrected....


Again....


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## swampyankee (Jan 18, 2014)

FLYBOYJ said:


> This would depend on the aircraft. I could tell you that tip tanks did not reduce the bending moment on the T-33 during certain speeds and flight attitudes..
> 
> 
> .



I am surprised by that, but I don't disbelieve you. Probably, there are also conditions where the tanks could worsen torsional loads.


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## FLYBOYJ (Jan 18, 2014)

swampyankee said:


> I am surprised by that, but I don't disbelieve you. Probably, there are also conditions where the tanks could worsen torsional loads.


The larger tip tanks do some un-nerving things at higher speeds and in dives.


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## N4521U (Jan 19, 2014)

How did tip tanks contribute to the spin characteristics of the aircraft?


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## FLYBOYJ (Jan 19, 2014)

N4521U said:


> How did tip tanks contribute to the spin characteristics of the aircraft?


I was never in a T-33 during a spin but from what I understand it's not that bad even with the tip tanks. I'm told there is a tendency for the aircraft to pitch up and become inverted.


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## Glider (Jan 19, 2014)

I have seen a video of a Hunter in an inverted spin and its the stuff of nightmares.


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## gumbyk (Jan 19, 2014)

FLYBOYJ said:


> I was never in a T-33 during a spin but from what I understand it's not that bad even with the tip tanks. I'm told there is a tendency for the aircraft to pitch up and become inverted.



I'd think it would delay recovery, at least. The increased mass at a large distance from the centre of the spin would increase the rotational inertia.


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## davparlr (Jan 21, 2014)

One of my AF buds trained in an AT-33 prior to assignment to an OV-10 in Vietnam. I remember a few things he said. Taxing with a castoring nose gear was an experience, every T-33 had a different cockpit layout, the yaw indicator for gunnery was a string tied to the nose, and, rolling with full wing tanks took a little extra to stop.


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## swampyankee (Jan 21, 2014)

davparlr said:


> One of my AF buds trained in an AT-33 prior to assignment to an OV-10 in Vietnam. I remember a few things he said. Taxing with a castoring nose gear was an experience, every T-33 had a different cockpit layout, the yaw indicator for gunnery was a string tied to the nose, and, rolling with full wing tanks took a little extra to stop.



A friend (who was in AFROTC) got to take a demo flight in a T-33. He was about 6 ft 3 in, most of which seemed to be legs. When he was fastened into the aircraft, the ground crew man who did it took one look and said "don't eject; the instrument panel will take off your legs."


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## VBF-13 (Jan 21, 2014)

I would think the tip tanks would draw the fuel uniformly so as to not upset the aerodynamics.


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