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aviatecar
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Rear Cargo Door Fitted to DHC-8?

Tue Jan 02, 2018 8:04 pm

Hello Gurus:

I noticed that there are already some STCs that converts DHC-8 to freighters. Just curious how difficult it is to have a rear cargo door (tail loading cargo gate like military transporters). I suppose the tail needs to be raised to make room and the APU needs to be relocated but I would like to hear opinions from some experts on this subject. Also, I guess pressurized cabin will make rear cargo door more difficult to design.

Thanks,

Chris
Last edited by atcsundevil on Tue Jan 02, 2018 8:26 pm, edited 1 time in total.
Reason: Removed all caps from title; clarified title
 
meecrob
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Re: Rear Cargo Door Fitted to DHC-8?

Fri Jan 05, 2018 1:13 am

You hit the nail on the head when you said "Also, I guess pressurized cabin will make rear cargo door more difficult to design." Any conversion that requires a change in the pressurized structure is probably more expensive to develop and install than customers would be willing to pay for.

If you are just asking theoretically, pretty much anything can be done, including the modification you describe, if you throw enough money at it. I'm not an aeronautical engineer, but I would guess it would be easier to start with a clean sheet aircraft than to modify a Dash 8 for what you describe.
 
SAAFNAV
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Re: Rear Cargo Door Fitted to DHC-8?

Fri Jan 05, 2018 2:00 pm

As Meecrob has said, anything can be done if you throw enough money on it.

A cargo ramp is only useful to load vehicles or really long objects.

I'm not familiar with the DHC-8, so don't know if it is wide enough to take a car. Apart from that, the floor needs to be strong enough to handle concentrated loads on a tread-way.
I don't know what 'type' of freighter they envision the DHC-8 to be, but I think with the rear side-opening cargo door it will be a useful 'small pallet' type of plane, as well as all the stuff that can fit through the door and be tied down, instead of a vehicle carrier type of plane.

As you stated, the APU will have to be moved, and probably some control lines/wiring etc, depending on where it is already.

A big problem in the field would be clearance underneath the tail. If you need a forklift to offload where a bed-loader is not available, you would be limited by the height of the forklift, and hence limiting the cargo weight to the forklift size.

How big of an engineering challenge it will be to design the door to withstand the pressure differential remains to be seen. I know at least on the C-130 it isn't a really complicated design: the door that opens inwards is forced close by the differential pressure with a small locking mechanism to prevent it banging up and down when depressurised, and the ramp 'hangs' on 5 locks either side that is attached to fuselage frames.

If you want a rear-ramp freighter, something like the C-295 that was designed that way would be cheaper.
L-382 Loadmaster; ex C-130B Navigator
 
stratclub
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Re: Rear Cargo Door Fitted to DHC-8?

Sat Jan 06, 2018 7:27 am

A very good place to start is the DC8's STC's And SSTC's . https://www.federalregister.gov/documen ... -airplanes

The answer is most likely there but will require some digging. As far as adding a main deck cargo door many aircraft started life as PAX only and were converted to cargo with a Main deck cargo door and a cargo handling system added after they became to expensive to maintain for Part 125 operations.

http://www.aircargopedia.com/passengertofreightpg.htm
 
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aviatecar
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Re: Rear Cargo Door Fitted to DHC-8?

Sun Jan 07, 2018 7:02 am

Thank you guys for the thoughtful responses.

I am not planning anything particularly just really curious about how the door thing works on a pressurized aircraft.

Some cargo conversion STCs includes a large cargo door modification which is very difficult already. However, I cant stop thinking a rear open door would always be better.

A clear sheet design probably makes more sense if there is actually that demand. Or aircrafts like C295 OR An-132 might be just good alternatives.

Thanks again!
 
SAAFNAV
Posts: 448
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Re: Rear Cargo Door Fitted to DHC-8?

Sun Jan 07, 2018 9:49 am

aviatecar wrote:
Thank you guys for the thoughtful responses.

I am not planning anything particularly just really curious about how the door thing works on a pressurized aircraft.

Some cargo conversion STCs includes a large cargo door modification which is very difficult already. However, I cant stop thinking a rear open door would always be better.

A clear sheet design probably makes more sense if there is actually that demand. Or aircrafts like C295 OR An-132 might be just good alternatives.

Thanks again!


Mechanically speaking, there isn't much difference between a ramp opening downwards, or a side cargo door opening upwards.

Both of them are outward opening doors, so to ensure them being able to withstand differential pressure, the locking mechanics just has to 'make the door structure part of the airplane structure'.

The Dash 8 already has the entrance door and baggage door opening outwards, so imagine the same type of interlocking set-up, only much beefier.
L-382 Loadmaster; ex C-130B Navigator
 
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aviatecar
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Joined: Tue Jan 02, 2018 3:44 am

Re: Rear Cargo Door Fitted to DHC-8?

Mon Jan 08, 2018 2:54 am

SAAFNAV wrote:
aviatecar wrote:
Thank you guys for the thoughtful responses.

I am not planning anything particularly just really curious about how the door thing works on a pressurized aircraft.

Some cargo conversion STCs includes a large cargo door modification which is very difficult already. However, I cant stop thinking a rear open door would always be better.

A clear sheet design probably makes more sense if there is actually that demand. Or aircrafts like C295 OR An-132 might be just good alternatives.

Thanks again!


Mechanically speaking, there isn't much difference between a ramp opening downwards, or a side cargo door opening upwards.

Both of them are outward opening doors, so to ensure them being able to withstand differential pressure, the locking mechanics just has to 'make the door structure part of the airplane structure'.

The Dash 8 already has the entrance door and baggage door opening outwards, so imagine the same type of interlocking set-up, only much beefier.



I see. the locking mechanism is the key to keep the aircraft structurally capable for pressurized operations!

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