• Hi Guest! Forum rules have been updated. All users please read here.

F-4 Phantom and Wing-Loading

KJ_Lesnick

ACCESS: Top Secret
Joined
Feb 13, 2008
Messages
1,033
Reaction score
26
From numerous sources, it would seem the F-4 Phantom had a somewhat heavily-loaded wing (medium, medium-heavy).

I'm not saying I dispute this as the F-4's performance obviously reflects it, but I am wondering how an aircraft with such large wings, which appear to be substantially cambered, fairly thick for a supersonic design, and not exactly razor sharp at the leading edge (all things that generally reflect a high L/D ratio) would yield a somewhat heavily-loaded wing?


KJ Lesnick
 

sferrin

ACCESS: USAP
Senior Member
Joined
Jun 3, 2011
Messages
13,382
Reaction score
1,422
KJ_Lesnick said:
From numerous sources, it would seem the F-4 Phantom had a somewhat heavily-loaded wing (medium, medium-heavy).

I'm not saying I dispute this as the F-4's performance obviously reflects it, but I am wondering how an aircraft with such large wings, which appear to be substantially cambered, fairly thick for a supersonic design, and not exactly razor sharp at the leading edge (all things that generally reflect a high L/D ratio) would yield a somewhat heavily-loaded wing?


KJ Lesnick

Wing loading is simply the weight divided by wing area. Things like camber, leading edge design etc. to enter into it.
 

KJ_Lesnick

ACCESS: Top Secret
Joined
Feb 13, 2008
Messages
1,033
Reaction score
26
Well I meant L/D ratio vs speed and such, not necessarily just wing-area vs weight.
 

overscan (PaulMM)

Administrator
Staff member
Joined
Dec 27, 2005
Messages
12,355
Reaction score
3,377
F-4 had a reasonable wing loading for its era and mission. It had a relatively high wing loading compared to a MiG-17 perhaps, but that's rather irrelevant, they are planes from different eras, and it didn't seem to help the MiG-17's poor kill ratio.
 

cat-shot

ACCESS: Restricted
Joined
Feb 1, 2008
Messages
11
Reaction score
0
KJ_Lesnick said:
From numerous sources, it would seem the F-4 Phantom had a somewhat heavily-loaded wing (medium, medium-heavy).

I'm not saying I dispute this as the F-4's performance obviously reflects it, but I am wondering how an aircraft with such large wings, which appear to be substantially cambered, fairly thick for a supersonic design, and not exactly razor sharp at the leading edge (all things that generally reflect a high L/D ratio) would yield a somewhat heavily-loaded wing?


KJ Lesnick

Among other things, a well-designed fighter aircraft should have moderate wing loading (between sixty and seventy-five pounds per square foot,
and a high thrust-to-weight ratio.
Aircraft engines from the Vietnam era produced combat thrust-to-weight ratios ranging from 0.75:1 for the F-105 Thunderchief ( with a W/S=91) to
0.87:1 for the F-4 Phantom II.
F-4B/C had a wing loading of 86,
The F-4E had a wing loading of 101,
The wind tunnel models (5%scale) tested at NACA/NASA had a wing loading of 65.
Advances in material technologies and turbojet engine design allow modern fighter aircraft, such as the F-15 Eagle and the F-16 Falcon, to have
thrust-to-weight ratios of equal to or greater than 1:1.Thrust-to-weight ratio governs an aircraft's acceleration and climbing performance.
An aircraft with a 1:1 thrust-to-weight ratio can maintain vertical flight. If the thrust-to weight ratio exceeds 1:1, the aircraft can accelerate in vertical flight.
 

KJ_Lesnick

ACCESS: Top Secret
Joined
Feb 13, 2008
Messages
1,033
Reaction score
26
Cat-Shot,

Among other things, a well-designed fighter aircraft should have moderate wing loading (between sixty and seventy-five pounds per square foot,
and a high thrust-to-weight ratio.

What is considered to be a light wing-loading then if 60-75 lbs/ft^2 is moderate?

Aircraft engines from the Vietnam era produced combat thrust-to-weight ratios ranging from 0.75:1 for the F-105 Thunderchief ( with a W/S=91) to
0.87:1 for the F-4 Phantom II.
F-4B/C had a wing loading of 86,

I assume W/S means something to the effect of wing-loading?

Are you talking about the wing-loading that you'd see on the F-4 in an air-to-air configuration? Or are you talking about a fully loaded Air-to-Ground set-up? I wouldn't have thought, even fully loaded that the F-4B/C had a wing-loading so close to the F-105 who's wings were absolutely tiny...

The F-4E had a wing loading of 101,

I thought the F-4E weighed the same as the F-4C? 101 lbs/ft^2 is higher than even the F-105...

The wind tunnel models (5%scale) tested at NACA/NASA had a wing loading of 65.

Why such a huge difference? Was this based on the weights encountered in air-to-air missions, or did they make some kind of a mistake?

Thrust-to-weight ratio governs an aircraft's acceleration and climbing performance.
An aircraft with a 1:1 thrust-to-weight ratio can maintain vertical flight. If the thrust-to weight ratio exceeds 1:1, the aircraft can accelerate in vertical flight.

This I am aware of
 

TinWing

ACCESS: Top Secret
Senior Member
Joined
Jan 3, 2006
Messages
888
Reaction score
49
overscan said:
F-4 had a reasonable wing loading for its era and mission.

Indeed, the F-4 had to manage a minimally acceptable approach speed for carrier landings, while accomplishing supersonic performance that was the equal of any land based type. I really can't imagine how a lower wing loading could have been accomplished at the time, as the F-4 design appears to have been a near optimal compromise, given the technology of the time. A larger conventional wing would have reduced performance, while a smaller wing would have increased an already marginal 150 knot approach speed. Obviously, it was too soon for variable geometry, and a delta wing would have been unworkable for a number of reasons.
 

KJ_Lesnick

ACCESS: Top Secret
Joined
Feb 13, 2008
Messages
1,033
Reaction score
26
I don't know why, but it just boggles my mind that a wing of that size, with some camber, apparently reasonable thickness, and the fact that it doesn't have the sharpest leading edge (which generally is favorable for low-speed handling) would behave like it did, and especially the fact that it needed not just trailing edge flaps with blown air, but leading-edge devices with blown air.

Maybe I'm missing something, but...


KJ Lesnick
 

r16

ACCESS: Secret
Joined
Apr 27, 2007
Messages
377
Reaction score
10
wing loading is just a basic parameter to get an impression , to make quick calculations . Bf-109 in early models could nearly match contemporary Spits and Hurricanes with its De Havilland patented leading edge devices , ı forgot what they were called . And similarly a P-47 wing would give the same wing loading on the F-16 since it has the same area but times change .
 

KJ_Lesnick

ACCESS: Top Secret
Joined
Feb 13, 2008
Messages
1,033
Reaction score
26
R-16,

Yeah, but I'm not talking about comparing a 1940's plane to a 1950's plane. I'm comparing two 1950's era planes (The F-105 and F-4). One has a wing-area of 565 square-feet and the other has a wing-area of 385 square feet, and yet they have wing-loadings that are surprisingly close...

KJ Lesnick
 

red admiral

ACCESS: Top Secret
Joined
Sep 16, 2006
Messages
616
Reaction score
74
The F-105 and F-4

But the F-4 is rather heavier than the F-105 so the lifting force produced by the wing must be bigger to support it, which generally means a bigger wing.
 

overscan (PaulMM)

Administrator
Staff member
Joined
Dec 27, 2005
Messages
12,355
Reaction score
3,377
Wing loading is weight divided by wing area. I fail to see how this can be difficult to understand. If one plane has smaller wings but weighs less its wing loading can be identical to a plane with larger wings but heavier.
 

r16

ACCESS: Secret
Joined
Apr 27, 2007
Messages
377
Reaction score
10
not that anybody asked for it , but let me offer what ı think . It is probably a mental exercise that forms the basis of this discussion ,which might be about whether it was possible to make a better Phantom or to improve it later ,say like at the F-4E/J period etc etc . ı don't know , am just speculating .

aircraft design is a confusing mess of various disciplines and as one might have to live with the results for decades , utmost care is needed to make sure that what you decide to produce ends up good , which calls for long and careful analysis . But of course you have to start somewhere , from a fixed point so that you can examine the alternatives . ı will speculate , without any evidence but by just a personal belief that the fix in the case of F-16 was the wing . Aspect ratio of 3 , thickness ratio of 4 , area of 300 square feet ; they probably took a wing that was throughly researched and known ( maybe as an academic endeavour ) and built the Falcon around it . ı can visualise a couple of people looking at a chart that said at this speed , the wing produces that much lift and the projected weight means lots of performance is lost so they decide to build a 9G airframe instead of the 7.33 costumary and required . Because the wing can be useful up to a higher AoA than the standarts of the day , they decide to use the underbelly inlet instead of a more costumary side bifurcated or a F-8 like nose inlet solution .( The most common and - ı hasten to add - realistic explanation is Harry Hillaker pruned the nose and the tail area to save weight and drag but ı am r16 ; ı have a reputation to maintain .) The result cuts down the space for the underbelly pylon or threatens more FOD risk and forms a flat underbelly that makes the cockpit bulge , which causes the seat to be angled to nearly twice of usual to cut down the increased drag but in the end the engine can cope with anything so it is left raised for visibility concerns . And so on .

on the other hand the fix for the Phantom of 1958 is without doubt the preceding Voodoo / Demon series . Now , ı have this Casio FX-3600P pocket calculator which ı think first came to know in about '88 and bought one of my own in 1990 , when ı thought ı might hack being an industrial engineer . Having failed , ı use the thing for calculating household bills . If there was a way of moving that calculator back to '58 , ı would be very rich or very dead . Another way of saying that the engineers of that were limited in the way of tools they could use . Basing their new designs on the experience they had was necessary to avoid surprises and Russians were masters of the evolutionary approach .ı think it is possible to say that Su-15 is a descendant of the Mig one . One of the most revolutionary western companies , Lockheed started U-2 from the F-104 .

returning to F-4 the wing might also be compromised for the need to have the fuel volume to feed the J-79s . According to a cutaway ı have the integral tanks in the wings form nearly 34% of the internal fuel load of an F-4E . In the previous models assuming everything was similar apart from the 318 lt # 7 tank put on the Es the ratio would climb up to 35.5. And as USAF versions needed bulges to house thicker wheels the wing was probably not "thick enough" . So , checking wing profiles from the period and discussing why this profile was chosen instead of that might not be exactly fair .

it might already been pointed through PMs but the ( W / S =91 ) value given for the F-105 means Weight divided by Surface area of the wing gives 91 pounds per square feet . 101 pounds per square feet of the Phantom works out to 24280 kg which ı would believe to be an air to air take off weight probably with external tanks . ı remember the air combat weight for a Phantom as 19400 kgs ( with 4 sparrows and half internal fuel ) and that would be about 81 pounds per square feet . The 86 given for B/C variants might be calculated through other assumptions . Boyd et all preferred using 100% internal fuel . Regarding 65 pounds on the 5% windtunnel models , the reason is probably the models are hollow inside and are not fully representative of an aircraft . But ı can't guarantee of being right on that either .ı have seen it in a Bill Gunston book that objects grow in weight much faster than in dimensions .Growing everything exactly same a twice longer plane should have 4 times the wing area but be 8 times heavier . 530 sqfeet wing area on the real plane should be 1.325 on a 5 percent model which then would give 86 pounds of weight for the test article , multiplied by 20 x 20 x 20 , the end result would by be 689 000 pounds .All calculations through my beloved Casio . Well , it seems the windtunnel models were solid instead of hollow . In any case the models could not be fully equal to a full size aircraft .

and rereading my previous post ı think the leading edge devices on the Messerschmitt were patented by Handley Page .
 

KJ_Lesnick

ACCESS: Top Secret
Joined
Feb 13, 2008
Messages
1,033
Reaction score
26
Was the F-4's wing reasonably efficient at supersonic speeds? (It's hard to tell because of the camber and the sweep angles...) I'm just wondering if it could hold a supersonic speed (even if a fairly low one) without it's afterburners, because the F-106A, which was considered similar in performance could do this from what I've been told.

KJ Lesnick
 

Weasel Pilot

ACCESS: Restricted
Joined
May 24, 2009
Messages
14
Reaction score
0
I only have about 1,000 hours in the F-4 and even clean (double underlined) I doubt if it would stay super without burner. Hang anything on it and NO WAY! As to the Cadilac (106), maybe if you got it super in burner it would stay that way in mil, but it wasn't going super without help from the burner or trading off altitude.
 

Archibald

ACCESS: Top Secret
Senior Member
Joined
Jun 6, 2006
Messages
4,198
Reaction score
1,733
It happened to a French Crusader pilot, from a land base... he lifted off, found that the aircraft "behaved a little bizarre" landed only to be told the entire flight had been done with the wing tips folded. No kidding.


 
Last edited:

NUSNA_Moebius

I really should change my personal text
Joined
May 26, 2012
Messages
170
Reaction score
29
The addition of LERX for vortex lift probably would've made the wing much more effective as alpha rose, but would require a revised intake structure to handle the loads involved (and with it more weight). Not sure if the Phantom's wings were of high enough sweep to create a substantial enough vortex as with "proper" higher sweep deltas a la the Mirages, MiG-21 and F-106. The flat fuselage bottom of the F-4 I suspect created quite a bit of body lift, like on the F-5 and the teens series, so true wing loading becomes a bit dubious to actually calculate. Of course deltas and LERX reliant semi-deltas like the Viper need lots and lots of thrust to maintain energy in high alpha maneuvers because of all the induced drag. Kill the thrust, kill the energy-maneuverability.

And in the end, the F-4's performance could be "fixed" with more thrust as with the PW1120 equipped Kurnass 2000, benefiting all regimes of flight.
 

Archibald

ACCESS: Top Secret
Senior Member
Joined
Jun 6, 2006
Messages
4,198
Reaction score
1,733
plus it was extremely sleek and beautiful one of the cutest interceptors to ever grace the skies...
 

Zoo Tycoon

ACCESS: Secret
Senior Member
Joined
May 27, 2008
Messages
385
Reaction score
414
It happened to a French Crusader pilot, from a land base... he lifted off, found that the aircraft "behaved a little bizarre" landed only to be told the entire flight had been done with the wing tips folded. No kidding.

Taking off with the wings folded has been done a fair few times, even more than the events detailed in the links. Given that folding wing outer panels are now seeing application beyond carrier aviation, I wonder when the first commercial aircraft will add to the list?
 

galgot

ACCESS: Top Secret
Senior Member
Joined
Jul 6, 2006
Messages
896
Reaction score
904
Website
galgot.com
It happened to a French Crusader pilot, from a land base... he lifted off, found that the aircraft "behaved a little bizarre" landed only to be told the entire flight had been done with the wing tips folded. No kidding.

Taking off with the wings folded has been done a fair few times, even more than the events detailed in the links. Given that folding wing outer panels are now seeing application beyond carrier aviation, I wonder when the first commercial aircraft will add to the list?

I think it's done with the B 777X :
 
Last edited:

Zoo Tycoon

ACCESS: Secret
Senior Member
Joined
May 27, 2008
Messages
385
Reaction score
414
It happened to a French Crusader pilot, from a land base... he lifted off, found that the aircraft "behaved a little bizarre" landed only to be told the entire flight had been done with the wing tips folded. No kidding.

Taking off with the wings folded has been done a fair few times, even more than the events detailed in the links. Given that folding wing outer panels are now seeing application beyond carrier aviation, I wonder when the first commercial aircraft will add to the list?

I think it's done with the B 777X :

Not the first application of folding wings to a commercial aircraft;- I was thinking about the first time a commercial aircraft takes flight with the wings inadvertently folded as per these Navy examples.
 

galgot

ACCESS: Top Secret
Senior Member
Joined
Jul 6, 2006
Messages
896
Reaction score
904
Website
galgot.com
It happened to a French Crusader pilot, from a land base... he lifted off, found that the aircraft "behaved a little bizarre" landed only to be told the entire flight had been done with the wing tips folded. No kidding.

Taking off with the wings folded has been done a fair few times, even more than the events detailed in the links. Given that folding wing outer panels are now seeing application beyond carrier aviation, I wonder when the first commercial aircraft will add to the list?

I think it's done with the B 777X :

Not the first application of folding wings to a commercial aircraft;- I was thinking about the first time a commercial aircraft takes flight with the wings inadvertently folded as per these Navy examples.

Ahh sorry then :)
Anyways, if this appends with a 777X, we will have many pictures from the passengers.
 

RetiredAFGuy

20 years of Phantom Phun
Joined
Jan 10, 2019
Messages
11
Reaction score
8
And that was with a catapult. :eek:

NOT done with a catapult. That photo is a US Air Force F-4E out of Iceland that took off from a quite long runway with its wings folded. Since the F-4E had wings that were manually folded/unfolded by the ground crew, that photo is of a monumental foul-up or somebody intentionally took off that way as a bet or a dare.
 

sferrin

ACCESS: USAP
Senior Member
Joined
Jun 3, 2011
Messages
13,382
Reaction score
1,422
And that was with a catapult. :eek:

NOT done with a catapult. That photo is a US Air Force F-4E out of Iceland that took off from a quite long runway with its wings folded. Since the F-4E had wings that were manually folded/unfolded by the ground crew, that photo is of a monumental foul-up or somebody intentionally took off that way as a bet or a dare.
F4FoldedWings_0.jpg

Apparently it's happened more than once. :D
 

rooster

ACCESS: Confidential
Joined
Jun 21, 2019
Messages
187
Reaction score
65
One of guys I used to work with hated the phantom because of its wing loading and just generally hated the phantom calling it something like 50,000lb lead weight with wings that was uncomfortable to fly. I was really disappointed to hear someone I liked pissing all over the plane I had loved so dearly.
 

Similar threads

Top