Freight vs Passengers?

[Tyrion101]

I was just wondering if it was different flying passengers or freight in real life? IE like flyiing a 744 or a 744f, do the planes handle differently or are they pretty much the same thing with different tings in the back?

[propjob]

Freight doesn't complain.

Art

[mckeonj]

Freight doesn't need sick bags, so you can climb faster and turn tighter; otherwise everything is the same.

[vacman]

Freight doesnt line up near the aft lav causing weight&balance issues

[simmerdr]

Tyrion:

All previous posts are probably correct about no consideration being necessary for creature comforts for cargo load in the cargo aircraft...

But, more seriously, we can expect e.g. a passenger aircraft requiring a systematic conversion procedure to become a cargo aircraft including further streangthening of fuselage and modification of exits for easier loading/unloading etc. (thereby leading to different take-off and landing limits, for example). While driving past KORD today, I caught the relatively rare sight of a FedEx DC-10 (or MD-11?) taking off. It is probable that this was a passenger plane in its earlier life, and later converted to the flight specifications of a cargo freighter.

Art et al.:

I had once read about a pilot ferrying monkeys (instead of people) in a DC-3 aircraft in South America. I cannot recall the exact details, but it appears this live cargo somehow opened the doors of their enclosures and freed themselves in mid-flight. The pilots locked the cockpit door for the rest of the flight. When the plane landed, the monkeys had occupied the seats and were seen peering through the windows...so some consideration to such live cargo back there is due.......

[ReggieF5421]

Schedule is a big difference.

Passengers have to go at a certain time, arrive at a certain time. Quite often when thunderstorms or snow causes delays and cancellations - rather than going to a chapel and complaining to someone who can do something about the weather - passengers and their families want to blame the airline.

Freight goes when the load is ready, lands when possible.

I've never heard a story about a freight aircraft complaining about being stuck on the ramp in a diversion.

Now - live freight cargo does require some extra special procedures. Be it the regular FedEx flights that carry race horses, or special flights like the LAN Cargo trip with seven or nine elephants from Africa to Mexico City (http://www.gcmap.com/mapui?DU=nm&MS=...&SG=454&SU=kts).

[alaskancrab]

Freight goes when the load is ready, lands when possible.

Dunno about that.. UPS/FEDEX are on pretty tight schedules. If they left late it would be chaos for their controllers no?

[clayton6221]

Quote:
"But, more seriously, we can expect e.g. a passenger aircraft requiring a systematic conversion procedure to become a cargo aircraft including further streangthening of fuselage and modification of exits for easier loading/unloading etc. (thereby leading to different take-off and landing limits, for example)."

Exits are locked off so that they cannot be used, too much work to remove them.
Additional dedicated cargo doors are added for ease of operations as a freighter, meaning cutting out a big opening where one didn't exist before. This requires adding additional structure to take the load paths the skin and under lying structure was supporting. AKA the cargo door framing must carry the static and flight loading AROUND that new opening. This will change the weight and balance of the aircraft and must be measured and recorded to give one a good base line for loading the aircraft in service.
Weight and balance are measured as originally built and recorded into the planes initial certification and recorded with the necessary governmental agencies. If this is changed by modification of the airframe, then this must be redone.
Especially in the conversion you are speaking of.

Clay

[propjob]

Cargo conversions probably are operated closer to their maximum allowable takeoff weights more frequently since the density of freight is higher than passenger density. As Clay said, there's lots of structural beefing up to handle the concentrated loads.

Art

[mikeandpatty]

Freighter versions often have higher "Zero Fuel Weights" and maximum landing weights - makes a big difference in what you can carry. Passenger versions typically have lower Zero Fuel Weights - the maximum internal weight allowed, the rest of the weight up to maximum takeoff weight must all be fuel.

Consequently. a freighter might be able to take off with lots of internal weight and less fuel, still land without being required to burn a lot of fuel, etc - much more flexible. Jet pax and cargo planes are really affected by these factors because they carry a lot of fuel, and need to burn a lot between maximum takeoff weight and maximum landing weight.

A good way to get smart on all this is to look at different airplanes by searching the web for a certain plane and see if you can find:

-empty weight
-zero fuel weight
-maximum ramp (max taxi) weight
-max takeoff weight (slightly less than max ramp weight)
-maximum landing weight

You also must remember that a 747-400 or 747-400F (for instance) can come with three different manufacturer's engines - GE, P&W and Rolls Royce; and, within those manufacturers, different versions of the same basic engine. Usually the total thrust difference across all these combinations may only be 4000 lbs thrust per engine, but it does change some weight limits in some cases.

It is not unusual to find some differences in these numbers given by different sources; this is usually do to the fact that the reference source is using data for a version upgrade of some type or other; there are MANY of these upgrades on many types of airplanes in use today.

In spite of all this, a pax or freighter version with the same total thrust and similar weight will handle pretty much the same way, and have the same or similar airspeed limits such as max Mach number, best cruise speed, stall speeds, etc.

The FAA certifies these design limits - it's not the builder or user who makes the decisions.