F-4 empty weights, counterintuitive difference.

[TheGloriousTachikoma]

As far as I can find, the empty weight of the F-4E is listed in the range of 29,535 to 30,328 depending on source.

 

The F-4J seems to have an empty weight of 30,700lb, but another source seems to indicate the 30,328lb that a different source listed for the F-4E.

 

The general consensus seems to be that the F-4E is measurably lighter than the F-4J. This despite that the F-4E has roughly an extra 1000lb of aluminium and steel in front of the cockpit. Do the BLC, ram-air turbine, and wing fold hydraulics really weigh that much, or is there more that isn't terribly obvious such as larger, heavier MLG struts on the Navy birds?

[phantom]

I would guess its the navy specific strengthening for carrier ops that make the difference.

[GW8345]

You also have to take into account the different inflight refueling systems (i.e. probe vs receptacle), avionics (such as ACLS), engines and what each service consider aircraft basic weight to be, i.e. with or without the AERO-7 missile launchers, etc. Also, the F-4J had a much bigger radar, bigger landing gear, beef'er airframe and carried more internal fuel (larger/more fuel cells).

[TheGloriousTachikoma]

2 hours ago, GW8345 said:

 Also, the F-4J had a much bigger radar, bigger landing gear, beef'er airframe and carried more internal fuel (larger/more fuel cells).

 

My understanding was that the basic airframe itself was the same between all versions to keep costs down, and in terms of fuel, I also thought the F-4J and earlier only had six fuselage fuel cells where the F-4E added the 7th to balance out the cannon.

[GW8345]

The F-4J had seven fuselage fuel cells also (and an internal wing tank in each wing) for a total internal fuel capacity of 1393 gallons, the F-4E had a total internal fuel capacity of 1296.

 

To my knowledge the F-4E compensated for the gun weight by having a smaller (less weight) radar and a little less avionics (such as the ACLS).

 

I don't think the basic airframes were the same, IIRC the wings were different with the J's wing being thicker and beef'er.