B707 freighter payload limits 2

[rb1957]

On the B707, did the freighter version stengthen the fuselage (other than around the cargo door) ?

I'm assuming that the freighter version had the same all up weight as the passenger version, but how "lumpy" is the payload allowed to be ? localised payload lumps ?

does someone have a weight ans balance manual for a B707 freighter ?

 

[crackman]

rb1957

I did alot of work many years ago on external, internal loads, stress and FDT on B707-300C that were used as various special mission platforms for the military. There is definitely a unique set of design loads (several volumes) for both the 707-300B and 707-300C. As I recall there were particular mods incorporated on the wing for the increased loads including changes in strength. Obviously the center wing gets more heavily loaded due to cargo and if you know the 707, the center section is quite unique among Boeing aircraft. These beefedup aircraft are actually known in Boeing lingo as 707-300B/C Advanced. With respect to GW, the 300B and 300C are different depending on the fuel management system as I recall though the biggest diff was in the design flight weight with flaps up.
The Boeing 707 is a grand old airplane and well designed. I worked on the last ones built which went to the US Navy and became the E-6.

Hope this helps

James Burd
Avenger Aircraft and Services

 

[FieldTeam]

The B707-320C was designed as a convertible freighter or passenger aircraft (with combinations of the two available). The 320C is basically the 320B with the addition of the upper deck main cargo door, beefed up landing gear, structural strengthening to handle larger payloads, improved brakes and convertibility features. Externally, it looked the same as the 320B except for the additional leading edge flaps inboard of the inboard nacelles.

The 320C max takeoff weight with JT3D dry engines is 328,000#. Max landing weight is 247,000#. Main deck volume full cargo version 476+ft3. Lower lobe bulk volume 148+ft3.

The 320B max takeoff weight with JT3D dry engines is 316,000#. Max landing weight is 207,000#.

All numbers were original Boeing and most likely have changed since published.

Currently, the best examples of a fleet of B707-320C series aircraft is in the military E-8C Joint Stars aircraft, which are converted commercial 320C's made into an airborne radar aircraft. There are other fine examples (John Travolta), but the E8's were pulled from all over the world and reconditioned to excellent condition. Future re-engining (possibly the JT8D) will further enhance these AC.

 

[rb1957]

thx fieldteam,

i have most of that info already. what i was really looking for was payload limits, particularly payload distributions. i have a B707 W&B manual, which is a little confusing to read (lots of detail for the fwd cabin, not much on the rear, possibly 'cause the rear cabin pax layout was pretty much fixed), so i'd like to bounce my interpretations off someone more familiar with the material. knowing that there was a freighter version, i expect that there is "somewhere" the limits on how the payload can be concentrated.

 

[FieldTeam]

I hope this answers your question:
---for reference only----
The combined pound/inch loading of the main cabin, forward and aft lobes shall not exceed the maximum monocoque pound/inch run limitations for the 320C.
Lb/In run at arm" 222 to 575 = 90 lb/in
Lb/In run at arm" 575 to 960 = 113 lb/in
Lb/In run at arm" 960 to 1055 = 123 lb/in
Lb/In run at arm" 1055 to 1325 = 100 lb/in
Lb/In run at arm" 1340 to 1435 = 74 lb/in

Main cabin load limitations no to exceed 210 Lb/Ft2 over entire floor area and 260 between LBL and RBL 25. The floor is the entire surface area at WL 208.6, between LBL and RBL 64 and between arm 222 to 1435.

Of course, additional consideration not to exceed CG limits must be observed. MAC = 272.3", MAC LE = 763.0".
---for reference only---

 

[rb1957]

thx FieldTeam

 

[crackman]

Just as some additional information and obviously for use as Reference Only:

1G Main Deck Floor Loading Limits
from body stat. 380-1320: 90 lb/ft2; 34.3 lb/in lengthwise

The above are multiplied by the design ultimate flight (not crash) load factors:
Fwd of BS1440 = 6g up, 4g down, +-3g side, 1.5 fwd
BS1440-1676 = 8g down, 5.34g up, +-3g side, 1.5g fwd

The above comes from the fuselage equipment structures criteria report and stress reports for a 707-320C. Note that these are different for 707-300B/C series aircraft employed by the military. I worked on the E-3A, E-6A/B and E-8 Jstars. Also, just as an added note, be careful with respect to the crease beams (at side of body). These react all of the in plane shear floor loading and the MS are pretty much close to zero. We had a tough time doing mods to these aircraft stuffing them full of equipment and trying to keep positive MS on the crease beams. By the way, the crease beam allowables were based on boeing testing. In addition, make sure you are using the correct end fixity values (boeing established this by test on the 707) for the floor beam to frame connections if you are going to look at floor beam loading as well.

Good luck

James

 

[rb1957]

thx crackman