00:Home

10:Aircrafts

20:Carriers

30:Bases

40:Maps

50:R.O.E.

60:Crews

70:More

80:Story

90:Missions

11:Weapons

12:Armament

13:Targets

2015-02-09

17:47












 

Notes

 

 

 

 

VOUGHT  F7U-4

Cutlass

 

The story which didn't happen ... outside Atlantic Air Combat

 

 

     

Introduction
   
To say that the US Navy had not been impressed with the F7U-3/3M Cutlass would be an understatement as, in their view, it was an unreliable, underpowered lethal bird to fly.  Having said that, many reckoned the Cutlass was capable, and its peculiar flying characteristics might only need to be learned a bit further but as is, it was just a hangar lump.  The Cutlass had deficiencies, among them its hydraulics and engines...   Vought had further explored the possibilities offered by the design, and worked hard to fix the various reliability issues associated with the airframes in view to offer a beefed up A2U-1 attack version to be powered by J45WE18 engines.   So much the Navy actually ordered 250 A2U-1 with the first two batches receiving their serial numbers  (
138372/138417, and 139822/139867)before cancelling the order.
  
The reasons were two-fold : first, the Navy was giving up on Westinghouse.  They had been promised a 10,000 lbf engine for the -3, but only got an anemic powerplant, and an unreliable one for that matter.  It was a repetition of what happended with the J40, so the Navy was done with Westinghouse.   Second, the Navy now said they were looking toward multipurpose airframes rather than specialized ones, hence their selecting the F4H1 Phantom II as their future main aircraft to operate from the super carriers now being commissioned.
  
This didn't discourage Vought.  For one thing they knew real multipurpose aircrafts were far down the line (Vought was already working on a future ... attack aircraft, to become the A-7 Corsair II), but more importantly,  there were plans to extend the life of the Essex class carriers, and the F4H1 was judged too large an aircraft to safely operate from these smaller platform (the Royal Navy proved later this assumption to be wrong, but that's another story).  The Cutlass offered ample room for development, and the the USMC had not been too amused with the USN cancelling the A2U-1.  The Marines had the powers to trigger a separate line of procurement, it only called for the opportunity to use them.
  
So Vought approached the Marines and asked what would make them happy.  The USMC simply reponded : heavy hauler, flexible, multipurpose, truly supersonic, reliable.  In other words, the F7U-3M and A2U-1 merged into a single improved airframe.  Besides adapting the fuselage to the J52, the USCM wouldn't finance any (major) redesigning of the airframe, only accepting the wing surface increase (thus not the experimental elevon system).  As the Marines Commander put it : Give it punch and legs.  Can you do that ?   Give us a ring if you do !   Rather blunt but it meant the USMC was indeed interrested to keep the assembly line open.

     

F7U-4 Development - A Proper Engine
   
However improved in many ways the A2U-1, which would form the basis of the F7U-4 , the Cutlass fuselage was still designed around the 34 inch diameter J46 engines, and would not cope with any wider engine without major redesign, which Vought could not sell.  But soon after the A2U-1 contract was cancelled in 1954, a couple of new engines had emerged, in particular the promising J52 from Pratt & Whitney.
   
It had been flown in its P3 "expendable" format intended for the AGM-28 stand off missile, but that version had evolved from a conventional J52-P-1, and P&W guaranteed they could produce an afterburning J52-P-4 version adding roughly 33% to the proven basic thrust of 7,500 lbf.  Actually, they were working on a mored advance version planned for  8,500 lbf of dry thrust, with at least 11,000 lbf being expected from an afterburning variant.   Actually, J52-P-6 prototypes had already passed the 150 hours bench test but hadn't been flown yet, meaning there wasn't much difference between proven/flown and announced peformances, a situation Vought hadn't been accustomed to recently, as far as the Cutlass was concerned.  A pair of J52P6C might not make the F7U-4 compete with the Crusader for speed at altitude but would nevertheless make the Cutlass truly supersonic.

  Engine       
mm
Length
mm
Weight
lb/@
Power
Dry
lbf/@
Power
Dry
Total
SFC
Dry
Power
AFB
lbf/@
Power
Dry
Total
SFC
Wet

Intalled

-

Speed
30

Mach
000 ft
















1J71A2 1067 7285 4086 9500 - 0.97 14400 - 1.98

F3H2M

Demon

563.kts

0.95
1J57PW20 988 6200 4750 10700 - 0.77 18000 - 2.80

F8U2N

Crusader

972.kts

1.65
1J65W18 953 5050 2740 7700 - 0.85 10500 - 1.95

F11F1

Tiger

632.kts

1.07















2J46WE8A 864 5029 2100 4020 8040 1.01 5725 11450 2.50

F7U3M

Cutlass

591.kts

1.00
2J46WE18 864 5050 ?_2320 ?_6100 ?_8687 ?_1.10 ?_8090 ?16190 ?_2.50

A2U1

Cutlass

632.kts

1.08
2J52P4A 814 5050 2350 7500 15000 0.89 10000 20000 1.92

=

=

799.kgs

1.35
2J52P6C 814 5050 2350 8500 17000 ?_0.85 11330 22660 ?_1.85

=

=

829.kts

1.40
2Orpheus.12R 823 2101 1762 6811 13622 0.976 8170 16340 1.62

=

=

= =















2RM5 (Avon) 907 5050 2885 10560 21120 0.932 14685 29370 1.85

J32

Lansen

=

=
2Atar 101G 940 6450 1916 8150 16300 1.06 9692 19384 1.95

MD456

SMB2

645.kts

1.09
2J65W18 953 5050 2740 7700 15400 0.85 10500 21000 1.95

F7U4

Cutlass

795.kts

1.35
     

"Give it legs..."
   
Fuel consumption was a problem plaguing all early jets, and in particular the J46 powered Cutlass.  Besides higher thrust, the P&W J52 offered much better fuel efficiency, and further improvements were due in that respect.  Then fuel capacity, preferably internal, was always a subject of its own, and it had evolved considerably since the F7U-1, with the capacity of several fuel tanks being adapted as various items of equipment had to be placed.  Vought did their best in trying to please USMC's Leather Necks.  Naturally, the small fuselage tanks planned to replace the port pair of guns on the A2U-1 had disappeared as the two pair of guns were maintained (the USMC motto " a Marine is first a soldier and a rifle" seemingly also applied to aircrafts, as no reduction in guns armament was accepted), but Vought nevertheless managed to minimize the impact of that choice, squeezing the largest iteration of each fuel tank evolution without any significant redesign of the aircraft.

Fuel Cells
(
US gal)
8-Stb
Wing
6-Stb
Wing
4-Stb
Wing
1
Fuselage
2
Fuselage
3
Fuselage
10+11
Fuselage
5-Port
Wing
7-Port
Wing
9-Port
Wing
Total Belly
Pod
Wings
Inner
Wings
Outer
TOTAL















F7U-1 105 144 86 150 151 = = 86 144 105 971 = 2250 - 1471
F7U-3 = 180 92 238 180 340 = 110 180 = 1325 1210 2150 - 1845
F7U-3M 124 180 91 244 180 340 = 107 180 124 1570 1210 2150 - 2090
A2U-1 136 175 103 241 180 340 24+60 103 175 136 1673 1210 2150 - 2193
F7U-4 136 180 110 244 180 340 = 110 180 136 1616 1140 2300 2150 2656
     

Externally, the 210 US gallons belly fuel pod (or FFAR launcher for that matter) had never been popular, partly because it was non standard in shape and size.  The USMC asked to revert to the 250 USgal used of the F7U-1, but now with either the 150 USgal or 300 USgal Douglas designed streamlined drop tanks becoming standard items aboard carriers, Vought thought better to reinforce the wings inner pylons for the larger model, and make the outer pylons (re: F7U-3M) able to carry the smaller type.

The main fuselage pylon was also of the "wet" type in order to carry a D-827B buddy refueling pack.  However, the USMC suggested a the adoption of a modified 150 US gal tank, a little shorter, that would fit between the nose landing doors and the arresting hook.  The resulting 140 US gal tank further improved on Vought's work and offered the Cutlass eleven different external fuel loads configurations :

External Fuel Wings
#12
250lb
Wings
#10
1000lb
Wings
#08
250lb
Wings
#06
250lb
Wings
#04
2250lb
Fuselage
#02
250lb
Fuselage
#00
1000lb
Fuselage
#01
250lb
Wings
#03
2250lb
Wings
#05
250lb
Wings
#07
250lb
Wings
#09
1000lb
Wings
#11
250lb
Main application
All













140 US gal

- - - - - - [140gal] - - - - - - Air-to-Air

300 US gal

- [150gal] - - - - - - - - - [150gal] - Air-to-Surface

300 US gal

- - - - [150gal] - - - [150gal] - - - - Air-to-Air

440 US gal

- [150gal] - - - - [140gal] - - - - [150gal] - Air-to-Surface

440 US gal

- - - - [150gal] - [140gal] - [150gal] - - - - Air-to-Air

600 US gal

- - - - [300gal] - - - [300gal] - - - - Air-to-Air

600 US gal

- [150gal] - - [150gal] - - - [150gal] - - [150gal] - (none)

740 US gal

- [150gal] - - [150gal] - [140gal] - [150gal] - - [150gal] - (none)

740 US gal

- - - - [300gal] - [140gal] - [300gal] - - - - Air-to-Air

900 US gal

- [150gal] - - [300gal] - - - [300gal] - - [150gal] - Recce/Tanker

1040 US gal

- [150gal] - - [300gal] - [140gal] - [300gal] - - [150gal] - ferry flight
Sorted













140 US gal

- - - - - - [140gal] - - - - - - Air-to-Air

300 US gal

- - - - [150gal] - - - [150gal] - - - - Air-to-Air

440 US gal

- - - - [150gal] - [140gal] - [150gal] - - - - Air-to-Air

600 US gal

- - - - [300gal] - - - [300gal] - - - - Air-to-Air

740 US gal

- - - - [300gal] - [140gal] - [300gal] - - - - Air-to-Air

300 US gal

- [150gal] - - - - - - - - - [150gal] - Air-to-Surface

440 US gal

- [150gal] - - - - [140gal] - - - - [150gal] - Air-to-Surface

900 US gal

- [150gal] - - [300gal] - - - [300gal] - - [150gal] - Recce/Tanker

1040 US gal

- [150gal] - - [300gal] - [140gal] - [300gal] - - [150gal] - ferry flight
     

Refueling Probe
The short stubby probe installed through the radar nose on the F7U-3M was a nuisance.   Not that it interferred that much with the radar, but it was completely out of the pilot's line of sight making inflight refueling manoeuvres quite an excercise.   For the F7U-4, Vought adapted a retractable probe on the port side of the fuselage, similar to the one which would later be adopted for the F8U Crusader.  All together, the type now had some legs indeed.

     

"Give it punch..."
   
The F7U-3, with its 1500 lbs ventral pack, and two 2,000lb inner pylons had shown it could carry some real weights, and the F7U-3M did even better with its 1,000lb outer pylons, even if mainly intended to carry AIM-7 Sparrow missiles.  Vought had examined the installation of additional pylons either under the fuselage or wings for the A2U-1 without having had the opportunity to finalize a solution.   With the increased thrust now secured, Vought looked at the matter once more which lead to another evolution of the number of pylons.  Vought not only went for both, but also restressed the inner wing pylons up to 2250 lbs to allow for the 300 USgal fuel tanks, and to cater for triple 750lb bombs launchers.  Finally Vought provided for eight HVAR launchers between the outer wing pylons.
   
In order to cater for the variety of loads and dimensions, Vought reverted to the original tails position (which had slightly moved inward on the A2U-1), thus avoiding major disruption on the existing F7U-3M assembly line, and moved the inner (main) wing pylon inward by 3 inches.  The rest was merely applying what had been prepared for the A2U-1.   Compared to its predecessors, the F7U-4 load carrying capacity would show as follows : 

Pylons (lb)
Hvar:140lb@
Wings
Hvar
Wings
#12
Wings
#10
Wings
#08
Wings
#06
Wings
#04
Fuselage
#02
Fuselage
#00
Fuselage
#01
Wings
#03
Wings
#05
Wings
#07
Wings
#09
Wings
#11
Wings
Hvar
Total Actual
Limit


















F7U-1 - - - - - 1750 - - - 1750 - - - - - 3500 3500
F7U-3 - - - - - 2000 - 1500 - 2000 - - - - - 5500 5500
F7U-3M - - 1000 - - 2000 - 1500 - 2000 - - 1000 - - 7500 6500
A2U-1 - 250 1000 250 500 2000 - 1500 - 2000 500 250 1000 250 - 9500 7000
F7U-4 560 250 1000 250 250 2250 250 1000 250 2250 250 250 1000 250 560 10620 7500


















Example Fuel - AIM9 Fuel - AIM7 - Fuel AIM9 - Fuel - - -
(lbs) 1000 - 155 2250 - 435 - 2250 155 - 1000 - - 7245 -


















Example Fuel - - 3750 - 1750 - 3750 - - Fuel - - -
(lbs) 1000 - - = 2250 - = 750 - = 2250 - - 1000 - - 7250 -


















Example Fuel - - Fuel - 2500 - Fuel - - Fuel - - -
(lbs) 1000 - - 2250 - = 1000 - 2250 - - 1000 - - 7500 -
     

Bombs Carrying
And with the use of in-flight refueling, an F7U-4 could take off with less than maximum fuel (ex: trading some for a pair of AIM9 for self defence).  Translated into maximum bomb capacity the F7U-4 had indeed become a real truck as short of the 3000 lb M118 bomb it could handle anything else in the US arsenal, and not in limited quantities, thanks the high number of external weapon stations and various types of carrying pylons and multiple ejector racks  designed to cater for either Korean War era types of bombs, or the new streamlined types now reaching arsenals in ever increasing number - Illustration

Bombs - Wings
#12
250lb
Wings
#10
1000lb
Wings
#08
250lb
Wings
#06
250lb
Wings
#04
2250lb
Fuselage
#02
250lb
Fuselage
#00
1000lb
Fuselage
#01
250lb
Wings
#03
2250lb
Wings
#05
250lb
Wings
#07
250lb
Wings
#09
1000lb
Wings
#11
250lb
Total Total

















Mk81 250 lb/@ 1 4 1 1 6 1 3 1 6 1 1 4 1 29 7250 lb
Mk82 500 lb/@ 2 4   2   4 2 14 7000 lb
M117 750 lb/@ 1 3   1   3 1 9 6750 lb
Mk83 1000 lb/@ 1 2   1   2 1 7 7000 lb
Mk84 2000 lb/@ 1       1 - 2 4000 lb
     

Missile Carrying
On the F7U-3M, the inner and outer wing pylons had been wired for either AIM-7 or AIM-9 missiles, but now all pylons were missiles capable allowing unprecedented flexibilty in weapons loads.  Although the USMC's intentions was to equip attack squadrons, their new F7U-4 could as well be dressed up for interception or aerial combat, either using AIM-9B/C Sidewinder or AIM-7 Sparrow missiles.  Even the USAF AIM-4 Falcon could be mounted, if necessary.  More the the point, the purpose of this ample missile carrying capability was essentially aimed at the handling of the AG-45 and AG-87 air-to-surface missiles, both in their respective standard (AGM-45 Strike and AGM-87 Focus) and anti-radar versions (ARM-45 Shrike and ARM-87 Sidearm).  But any mix between these various types were possible - Illustration.  Finally, dual rail launchers were made available, either for AIM-9/AG-87 or for AIM-7/AG-45 type of missiles, the latter allowing a mix of both categories.  The use of these dual launchers had however the consequence of making the neighbouring (light) pylons unavailable.

Missiles Wings
#12
250lb
Wings
#10
1000lb
Wings
#08
250lb
Wings
#06
250lb
Wings
#04
2250lb
Fuselage
#02
250lb
Fuselage
#00
1000lb
Fuselage
#01
250lb
Wings
#03
2250lb
Wings
#05
250lb
Wings
#07
250lb
Wings
#09
1000lb
Wings
#11
250lb
AIM9/
AGM87
AIM7
AGM45
















AGM87 or AIM9 1AG87 1AG87 1AG87 1AG87 1AG87 1AG87 1AG87 1AG87 1AG87 1AG87 1AG87 1AG87 1AG87 13 -
AGM45 or AIM7 - 1AG45 - - 1AG45 - 1AG45 - 1AG45 - - 1AG45 - - 5
















DR1/A 10 -
DR2/A - - - - - 6
     

Heavy and Light Rockets
As mentioned, the FFAR belly pod had never been popular, and 2.75" rockets were now better handled with specific tube-like dispensers, like the

LAU-32/A 6 FFAR (264 lb)  (real) LAU-56/A 32 FFAR (1079 lb)  (AAC fake)
LAU-40/A 12 FFAR (463 lb)  (AAC fake) LAU-58/A 36 FFAR (1222 lb)  (AAC fake)
LAU-51/A 18 FFAR (711 lb)  (real)

To cater for heavy rockets, Vought thus installed dedicated rails placed between the outer wing pylons.  As these weapons could also be released from missiles rails a heafty total of twenty six 5" HVAR could be carried (Illustration)      

Stbd Port
HVAR R
8
R
6
W
#12
R
4
W
#10
R
2
W
#08
W
#06
W
#04
F
#02
F
#00
F
#01
W
#03
W
#05
W
#07
R
1
W
#09
R
3
W
#11
R
5
R
7
Total























Launchers 1 1 1 1       1 1 1 1 8
                         
Pylons     1   1   1 1 1 1 1 1 1 1 1   1   1     13
                         
Combined 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 21
                         
Twin     1   1+1   1 1 1+1 1 1+1 1 1+1 1 1   1+1   1     18
                         
Combined 1 1 1 1 1+1 1 1 1 1+1 1 1+1 1 1+1 1 1 1 1+1 1 1 1 1 26
     

Photo Reconnaissance Version
While the function in itself was desirable, the nose of the aircraft was much too high from the ground for the aircraft cameras to be properly serviced, as demonstrated with the few F7U-3P already produced for the Navy.  Instead, the USMC opted to take advantage of the main fuselage pylon to carry a Recce Pod - a straightforward and cost effective approach, allowing to cater for any absence of dedicated aircrafts in a Air Carrier Group. 

     

F7U-4 Production
   
The USMC was prompt to get the backing of the US Congress for a confirmed order, and the assembly of the first new F7U-4 Cutlass just followed the last F7U-3M in August 1955.  Initial production rate of the first twelve airframes was deliberately slow, partly to allow Pratt & Whitney to catch up with the programme, and partly to incorporate various airframe and systems enhancements.  But with engines and "pre-production" aircrafts peforming as promised, pace increased somewhat over the following years only hindered by Vought being also fully committed in the production of their new F8U Crusader.
   
Serials (from the cancelled A2U-1 programme : 138372/138417, 139822/139867, and 140161/140310)

1955 138372 138383 12 12 1958 139860 139867 8
1956 138384 138407 24 24 1958 140161 140224 64 72
1957 138408 138417 10 1959 140225 140310 86
1957 139822 139859 38 48 242

Post 1962 Designation
Besides having received previously cancelled serial numbers (a non standard practice), the Cutlass was further handled in a non conventional manner as the USMC was insisting on keeping the "F-7" for their fighter.  The "7" slot was thus allocated at the to both teh XF-7A Sea Dart and the F7 Cutlass, not forgetting the A7 Corsair II, another Vought products : 

14 F7U-1 F-7A   14 : 124415   124428 46 F7U-3M F-7C   46 : 129699   129744
F7U-2 (not produced) 12 F7U-3P RF-7B   12 : 129745   129756
231 F7U-3 F-7B   28 : 128451   128478 A2U-1 (not produced)
154 : 129545   129698 242 F7U-4 F-7D (see above)
  49 : 139868   139917
      
Specifications
port

AIRCRAFT ID

F7U4 A2U1 - F7U3M F7U3 - F7U1

AIRCRAFT NAME

Cutlass Cutlass

-

Cutlass Cutlass

-

Cutlass











Engines 1 ID

Jet J52P6C J46WE18

-

J46WE8A J46WE8A

-

J34WE32

Engines 1 Number

Total 2 2

-

2 2

-

2

Engines 1 power continuous

hp or lbf 7500.lb 5493.lbf

-

3620.lbf 3620.lbf

-

3020.lbf

Engines 1 power max

hp or lbf 8500.lb 6100.lbf

-

4020.lbf 4020.lbf

-

3700.lbf

Engines 1 power extra

hp or lbf 11305.lb 8687.lbf

-

5725.lbf 5725.lbf

-

4900.lbf











Empty Weight

lb 17110.lb 17110.lb

-

17110.lb 17110.lb

-

12837.lb

Crew

200 lb/@ 200.lb 200.lb

-

200.lb 200.lb

-

200.lb

Fuel internal (full)

Volume (US gal) 1616.US 1673.US

-

1570.US 1325.US

-

971.US

Fuel internal (full)

Volume 1347.gal 1395.gal

-

1309.gal 1105.gal

-

810.gal

Fuel internal (full)

Weight (7.6 lb/gal) 10240.lb 10601.lb

-

9949.lb 8396.lb

-

6153.lb

Gun.1: 4M-03/20mm

4200 rpg (20x110) - -

-

- -

-

458.lb

Gun.1: 2M-12/20mm

2164 rpg (20x110) - 188.lb

-

-

-

-

-

Gun.1: 4M-12/20mm

4164 rpg (20x110) 376.lb -

-

376.lb 376.lb

-

-












Combat Weight

lb 27926.lb 28099.lb - 27635.lb 26082.lb

-

19648.lb











Pylon : wings outermost

port #11 250.lb 250.lb - - - -

-

HVAR : max weight

Port R1,R3,R5,R7 560.lb

-

-

-

-

-

-

Pylon : wings outermain

port #09 Volume (US gal) 150.US

-

-

-

-

-

-

Pylon : wings outer main

port #09 1000.lb 1000.lb

-

1000.lb -

-

-

Pylon : wings outer

port #07 250.lb 250.lb

-

-

-

-

-

Pylon : wings inner

port #05 250.lb

-

-

-

-

-

-

Pylon : wings inner main

port #03 Volume (US gal) 300.US 150.US

-

150.US 150.US

-

250.US

Pylon : wings inner main

port #03 2250.lb 2000.lb

-

2000.lb 2000.lb

-

2000.lb

Pylon : fuselg inner

port #01 250.lb

-

-

-

-

-

-

Pylon : fuselg central

= #00 Volume (US gal) -

-

-

210.US 210.US

-

-

Pylon : fuselg central

= #00 44FFAR pack 1000.lb 1500.lb

-

1500.lb 1500.lb

-

-

Pylon : fuselg inner

stb #02 250.lb

-

-

-

-

-

-

Pylon : wings inner main

stb #04 Volume (US gal) 300.US 150.US

-

150.US 150.US

-

250.US

Pylon : wings inner main

stb #04 2250.lb 2000.lb

-

2000.lb 2000.lb

-

2000.lb

Pylon : wings inner

stb #06 250.lb

-

-

-

-

-

-

Pylon : wings outer

stb #08 250.lb 250.lb

-

-

-

-

-

Pylon : wings outer main

stb #10 Volume (US gal) 150.US

-

-

-

-

-

-

Pylon : wings outer main

stb #10 1000.lb 1000.lb

-

- -

-

-

HVAR : max weight

stb R2,R4,R6,R8 840.lb

-

-

-

-

-

-

Pylon : wings outermost

stb #12 250.lb 250.lb

-

-

-

-

-












Total external loads

Theoretical (or less fuel) 10620.lb
38546.lb
  8500.lb
36599.lb

-

  7500.lb
35135.lb
  5500.lb
31582.lb

-

  4000.lb
23648.lb











Load carrying limit

Crew=1 & full internal fuel 7500.lb 7000.lb

-

6000.lb 5500.lb

-

4000.lb











Maximum take off

lb (MTOW) 35500.lb 35100.lb

-

32500.lb 32500.lb

-

24000.lb
     
Background Data (click on the thumbnails)

F7U-1






F7U-3






A2U-1

Source: http://forum.warthunder.com/index.php?/topic/73750-vought-f7u-3-cutlass/ 
Source:  "Chance Vought F7U Cutlass" by Steve Ginter
Source:  http://www.philsaeronauticalstuff.com/f7u-3m/f7u-3m.html (photographic walkaround of a F7U-3M)

___________