HS748 empty weight

[brucesim2003]

Hi guys,

I'm assuming that the empty weight given for Rick Piper's HS748 is for the airliner. Does anyone have any idea on what the empty weight would be for the freighter? I'm assuming (again) that removing all the fittings for the passengers would create a reasonable increase in useful load, but I don't know by how much. Also, assuming this is the case, do I only have to adjust the parameter "empty_weight" under "weight_and_balance", or are there other parameters I need to change?

Cheers


Bruce

[DaveB]

Hi Bruce

The figures I've got for the freighter vary a little. Some give a max payload of up to 6000kg and others give a slightly lower figure of 5216kg/11500lb.. the latter is probably more accurate. Operational dry weight of the freighter is 27000lbs/12247kg and MZFW is 38500lb/17460kg so take one from the other and you get your max payload of 5216kg/11500lbs. MGW is 46500lb/21092kg so if you're playing freight in flightsim, make sure the empty weight is 27000lbs and the MGW is 46500lbs.

Compared with the model (a quick look shows Rick put an empty weight of 25453lbs and a MGW of 46500lbs).. you're getting perhaps a completely empty airframe

EDIT..
The important thing for flightsim is the MZFW and this is a black art mate as there is nowhere to fit that figure in Best suggestion is to fart around with the empty weight until you get a MZFW (allowable fuel in the sim when loaded to 11500lbs) that matches what you want to see

ATB

DaveB

[brucesim2003]

Thanks Dave,

So if the freighter is 27,000lbs, what is the weight of the liner?

Cheers


Bruce

[DaveB]

Hi Bruce

Again.. this depends on where you look mate. The only cast iron info I have is for the Andover as I have the FM here but a quick search gives very similar figures of around some 27126lbs which in the grand scale of things is neither here nor there The info above for the freighter is from a current 748 freighter operator so it can be taken as read
Although you'd expect a saving in weight with all the carpets and finery stripped out (which you would get), you're still tied by the MZFW and there appears to be no difference between the freighter and the pax version.. by and large

ATB

DaveB

[NigelC]

Won't be any Max ZFW difference between pax and freighter .... it's a structural thang

[Paule]

Just to complicate matters, not all aircraft have an MZFW. If all the fuel is in the fuselage or wing centre tanks an MZFW is not required as the limiting structural factor is then the MTOW. Having an MZFW means that fuel is positioned outboard of the wing root to reduce the amount of upward bending the wing will have. You will probably find that most piston engined commercial aircraft have aspect ratios that don't need bend stress relief.

Paul

[DaveB]

Hi Nigel

Yup.. I wasn't sure if the freighters had been beefed up over the pax versions to enable them to take heavier loads but as the MGW for both types appears to be the same, that is unlikely so there'd be no difference in MZFW

For Bruce..
I'm not entirely sure where the 'empty weight' comes from in flightsim mate.. probably the same place you find out how long a piece of string is There's only a small difference between the empty weight for the model (which could possibly be dry) and the 27000lbs listed as OEW (operational empty weight) and really.. OEW is what you need to be looking at as when you fuel up in flightsim, you don't take on water or oil/lubricants. Depends on how real you want to get I suppose but for the sake of arguments.. the model default should be close enough

ATB

DaveB

[brucesim2003]

Thanks guys, I guess I wont be able to make a bit more $ in Air Hauler then

Cheers


Bruce

[DaveB]

I dunno mate.. do you get paid more for carrying dangerous cargo?? If so, there's always that option

ATB

DaveB

[NigelC]

Hello Dave

Floors might be beefed up but only in as much as point loading. Wing Spar/Fuselage remains the same.

Place a plank (Wing Spar) between two oil barrels (Main Gear)... as you increase the weight (fuselage and payload) on the plank, it will bend and eventually break, so the Max ZFW is a safe limit on that bending, hence centre tank fuel on other aircraft will be counted as payload IF the wing tanks aren't full.

Nige