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I'm trying to find any substantiation / design justification why none of the OEM/STC holders are able to provision nose cargo doors on A321 / B757 / B767 / B777 fleet as part of P2F (passenger to freighter) conversions.

I'm sure there would have some discussions/presentations on this, appreciated to guide with reference.

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    $\begingroup$ The obvious answer would be that such a modification would be too expensive compared to the potential benefit it adds $\endgroup$
    – 60levelchange
    Feb 8, 2021 at 10:12
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    $\begingroup$ One consideration on the A321 / B757 / B767 / B777 fleet: The cockpit is in the way. If you look at aircraft with nose cargo doors (747, C-5, An-124, An-225) the cockpit was placed with consideration for fitting a nose cargo door. The A321 / B757 / B767 / B777 fleet weren't. $\endgroup$
    – user1937198
    Feb 8, 2021 at 10:22

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The simple answer is there isn't the space. The problem with nose cargo doors is the cockpit. The cargo door must be high enough on the aircraft to line up with the main cargo hold to be useful. On larger aircraft designed with this in mind from the start, (747, C-5, An-124, An-225) the cockpit is placed in a location above the main deck so that the cockpit does not obstruct the path from the main cargo hold to the nose door.

This is specifically why the 747 was built as a two deck aircraft with the hump. When the 747 was originally being designed, Boeing thought that there was a significant risk that supersonic aircraft would fully replace the market for long distance passenger aircraft. So they wanted their long distance subsonic design to be a very competitive bulk freight aircraft in that scenario so it would still make money. Because of this they wanted to be able to fit a nose door, so they needed to put the cockpit on a raised deck, which left them with the hump deck for aerodynamic reasons.

However, on current generation narrow bodies, they simply aren't tall enough to do this. They are single deck aircraft, with the cockpit located directly in front of the main payload deck.

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  • $\begingroup$ How about than following concept of Swinging Tail, same like Dreamlifter. This should address the problem of Cockpit location. $\endgroup$
    – Prasanth
    Feb 8, 2021 at 12:21
  • $\begingroup$ That is a different question. $\endgroup$
    – user1937198
    Feb 8, 2021 at 15:02
  • $\begingroup$ and worse, the structural integrity of the airframe would be changed so much it'd need recertification as a new type, which is extremely expensive, making the entire process uneconomical. A small forward door could be handy to load containers and palletised cargo, but at the cost it's just not feasible $\endgroup$
    – jwenting
    Feb 9, 2021 at 21:24
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With all the connections between the cockpit and the rest of the aircraft, a modification which makes the cockpit swivel out of the way is way too complicated. In cases where a conventional airframe needed wide open access to its cargo hold, the tail would be made removable. The Junkers 52/1m would be one example, and the Conroy CL-44 "Skymonster" would be another. It was specially designed to ferry the large RB-211 engines for the Lockheed Tristar around.

The picture below was shamelessly copied from the Wikipedia article. Note the bulges near the tail: They cover the hinges for the sideways opening fuselage.

enter image description here

Regarding the presentations you desire: Those are all company-internal and not for public consumption.

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Other than the answer of there isn't space, you would need to cut open the airframe. When 747 passenger planes are converted into freighters they don't have a nose door. There is obviously space but cutting up the airframe would make legally getting it in the air again virtually impossible.

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  • $\begingroup$ But they also cut into the airframe to install the side cargo door. $\endgroup$
    – Bianfable
    Feb 8, 2021 at 16:52
  • $\begingroup$ And they do cut into the airframe to make the Dreamlifter. $\endgroup$
    – vasin1987
    Feb 8, 2021 at 21:47
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    $\begingroup$ @vasin1987 The Dreamlifter is barely legal: its certification is with the caveat that it can only carry cargo owned by Boeing which cannot be flown otherwise, unlike the Beluga which carries commercial cargo. The big technical compromises is that the Dreamlifter loses main cabin pressurization and the APU. $\endgroup$
    – user71659
    Feb 9, 2021 at 20:00
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    $\begingroup$ @Bianfable but they take a lot of care to not cut into major structural elements, which you would of necessity need to do to cut away the nose and part of the forward fuselage. $\endgroup$
    – jwenting
    Feb 9, 2021 at 21:25
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    $\begingroup$ @vasin1987 plus those are purpose built aircraft, not aftermarket conversions. They're basically classified as experimentals with some extra perks, not useful for sale to the general public (or indeed at all) $\endgroup$
    – jwenting
    Feb 9, 2021 at 21:26

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