Preighter aircraft

[sackett]

An article in today's wiki about "preighter" airplanes, specifically passenger planes used to haul freight during the pandemic, got me thinking.

Converting a passenger airliner to freight can be a very makeshift procedure, sometimes no more than securing crates and containers on and among the seats (and in those misbegotten overhead bins; well, it's an emergency after all). A better approach is to remove the seats, of course, but loading, unloading, and ground handling are still laborious.

Would it pay to build hermaphrodite airplanes, i.e., airliners with fuselages that can be converted to freight or passenger hauling AND HANDLING quickly? What changes to the entire airframe might this entail?

Does anybody here have any insights?

 

[Ziggurat]

An article in today's wiki about "preighter" airplanes, specifically passenger planes used to haul freight during the pandemic, got me thinking.

Converting a passenger airliner to freight can be a very makeshift procedure, sometimes no more than securing crates and containers on and among the seats (and in those misbegotten overhead bins; well, it's an emergency after all). A better approach is to remove the seats, of course, but loading, unloading, and ground handling are still laborious.

Would it pay to build hermaphrodite airplanes, i.e., airliners with fuselages that can be converted to freight or passenger hauling AND HANDLING quickly? What changes to the entire airframe might this entail?

Does anybody here have any insights?

No particular expertise or experience, but I doubt it's not worth it. Aircraft that get permanently converted from one type to another don't need a quick swap, since the time to do the swap is minimal in relation to the aircraft's service life. It's only useful if you plan on swapping back and forth, but such conversions are likely to be a rare occurrence. Custom designing, building, and certifying an aircraft interior just for such a rare event seems like it's far more trouble than it's worth.

 

[Trebuchet]

Boeing has, in fact, offered both "Convertible" and "Combi" aircraft in the past. The former had a large cargo door and palletized seats. The latter, in the 747 line, had a large cargo door and cargo space aft and passengers forward.
Neither was a big seller.

 

[theprestige]

One interesting aspect of military operations is that pure cost-effectiveness is almost never a major concern. Warfare tends to be essentially about getting the job done no matter the cost. So you'll often see the military pushing design envelopes and investing heavily in equipment that for-profit enterprises would never consider. Exhibit A: Rotary wing aircraft. The Air Force is where you'll find all the preighters.

 

[RecoveringYuppy]

The Air Force is where you'll find all the preighters.

Similar to what you said about cost being no object, isn't comfort not generally a concern? Wouldn't the Air Force convert a freighter to a passenger vehicle by saying "sit on the floor".

 

[Ziggurat]

Similar to what you said about cost being no object, isn't comfort not generally a concern? Wouldn't the Air Force convert a freighter to a passenger vehicle by saying "sit on the floor".

No, they will install seats. But it's still pretty spartan, and not the sort of conversion that airlines would be satisfied with:
https://upload.wikimedia.org/wikipe...3_130527-F-LK329-003.jpg/1280px-thumbnail.jpg

 

[sackett]

My thought was that pandemics and other enormities will occur again. Passenger travel will tank, while demand for urgent air shipping will increase. Readily convertible planes might prove to outperform the sometimes makeshift arrangement we've seen during Covid. Rapid turnaround can be critical, and that demands specialized equipment.

Hell, flying in a passenger-configured preighter couldn't be any more uncomfortable than in a dedicated flying tube.

 

[theprestige]

Similar to what you said about cost being no object, isn't comfort not generally a concern? Wouldn't the Air Force convert a freighter to a passenger vehicle by saying "sit on the floor".

I've had it happen on short trips in ground vehicles. But for major logistical operations, the Air Force will swap basic seats in and out depending on the nature of the next planned load. The point being that they can use the same planes for large troop movements and for large cargo shipments, with minimal alterations. Or both. Planes can be fitted out to transport a unit of soldiers in spartan seats, with the bulk of the interior being taken up by their equipment and supplies.

 

[Ziggurat]

My thought was that pandemics and other enormities will occur again. Passenger travel will tank, while demand for urgent air shipping will increase.

Maybe. But I don't think air shipment demands will increase so fast that airlines can't do a normal passenger to freight conversion.

Readily convertible planes might prove to outperform the sometimes makeshift arrangement we've seen during Covid.

I'm sure they would, but the costs aren't likely worth it.

Rapid turnaround can be critical, and that demands specialized equipment.

Critical for what? To fully capitalize on the potential profits from air shipments? Sure. But again, cost/benefit analysis doesn't necessarily favor that, given the costs to (again) not only develop, manufacture, and install such specialized and more expensive interiors, but also to go through all the regulatory hurdles necessary for passenger flight approval.

The spike in air shipment demand isn't going to be so critical that national security depends on it. And if it does, well, makeshift solutions would suffice, you could draft the entire civilian air fleet and not just the few planes you outfitted with swappable interiors, and military transport would get in on the act too.

Hell, flying in a passenger-configured preighter couldn't be any more uncomfortable than in a dedicated flying tube.

Oh, it can always get more uncomfortable.

 

[BowlOfRed]

Changing "quickly" is difficult. It takes time and you're paying crew to convert things rather than haul for your paying customers. If you could have a craft that you could convert a section from passenger to a cargo unit within an hour, to balance last-second demand, that would probably be useful.

Most of the time the passenger and cargo carriers are operating in different niches. Passenger flights need to be scheduled often and well in advance. The quantity of flights demand efficient aircraft. If your combi plane has lower per-passenger costs, the amount you get in cargo probably won't make up for the loss. You can't leave the plane on the ground if the cargo section is light, so balancing demand becomes a challenge.

I see the big obstacle is the initial sale. A new airliner is super expensive. You have to be a big operation to think you can get enough use out of the purchase. To my mind a premier air carrier that might get one of these is already squeezing everything out of the passenger side, so they don't want the less-efficient airframe. The non-premier carriers can't afford a new airframe anyway and are just picking up whatever is on the used market, which is older model passenger craft.

 

[Trebuchet]

Passenger airplanes carry a LOT of belly cargo anyhow. There's far more room down there than required for baggage. I suppose without passengers they could carry more weight in the holds.

 

[Delvo]

My thought was that pandemics and other enormities will occur again. Passenger travel will tank, while demand for urgent air shipping will increase. Readily convertible planes might prove to outperform the sometimes makeshift arrangement we've seen during Covid. Rapid turnaround can be critical, and that demands specialized equipment.

There's also the issue of who owns the planes. They're mostly two separate groups of companies.

* * *

The comparison with military cargo planes is interesting because of one of the main design features that makes their conversions from one load to another as easy as they are. It's the same thing that makes it possible to roll vehicles into & out of them: they're flat-bottomed. The structural issues that go into that shape result in a heavier plane, and avoiding weight is crucial in the civilian markets because it affects fuel consumption which affects cost to operate and range. The civilian airlines would have no interest in a heavier plane with the only benefit being its ability to do something that's rarely useful anyway.

 

[Ziggurat]

The comparison with military cargo planes is interesting because of one of the main design features that makes their conversions from one load to another as easy as they are. It's the same thing that makes it possible to roll vehicles into & out of them: they're flat-bottomed. The structural issues that go into that shape result in a heavier plane, and avoiding weight is crucial in the civilian markets because it affects fuel consumption which affects cost to operate and range. The civilian airlines would have no interest in a heavier plane with the only benefit being its ability to do something that's rarely useful anyway.

I suspect it's not just the weight. Military cargo planes also seem wider than civilian passenger planes. At a given passenger capacity, a narrow and long plane is going to be more fuel efficient than a short and wide plane, even ignoring weight differences, just because of air resistance.

 

[WhatRoughBeast]

My thought was that pandemics and other enormities will occur again. Passenger travel will tank, while demand for urgent air shipping will increase. Readily convertible planes might prove to outperform the sometimes makeshift arrangement we've seen during Covid. Rapid turnaround can be critical, and that demands specialized equipment.

All of that is true, but not necessarily as dominant as you seem to think

There's a question which your first sentences rather glossed over: pandemics will occur again - but how often? The last time we had something like the last year was the Spanish Flu, and that was 100 years ago.

If 100 years is the expected interval, a jet preighter with an estimated lifetime of 30 - 50 years makes no sense. It will be retired before its tradeoffs become advantageous. If you can convince everybody that the next pandemic will occur in 10 years, that's a different story.

Hell, flying in a passenger-configured preighter couldn't be any more uncomfortable than in a dedicated flying tube.

Oh my. You sweet child of privilege. I've ridden in passenger-configured C-130s and C141s, and trust me, I'll take a regular passenger jet any day.

 

[theprestige]

Well this does suggest an answer to a question I've had: How far does the airline customer's preference for low prices over comfort and convenience actually extend?

It's seemed clear to me for years that the reason air travel is so uncomfortable is because airlines have figured out that what people want more than anything is cheap flights, when they want them, where they want them. If there were enough customers willing to pay a premium for more luxurious accommodations, airliners would be entirely first class seats.

On the other hand, if the airlines thought customers would accept the trade-off, we'd have no better than military-grade seating on all flights.

 

[RecoveringYuppy]

My thought was that pandemics and other enormities will occur again. Passenger travel will tank, while demand for urgent air shipping will increase.

Maybe. But I don't think air shipment demands will increase so fast that airlines can't do a normal passenger to freight conversion.

Tend to think Ziggurat is correct but has anyone cited how much of an increase there was during the pandemic?

 

[sackett]

Here’s what I should’ve done first:

https://en.wikipedia.org/wiki/Preighter

Two passages from this article that struck me:

“Prior to the precipitous drop in air travel caused by the outbreak of COVID-19, cargo capacity in the belly hold of passenger aircraft accounted for half of global air freight, rising as high as 80% on transatlantic routes.”

“As there is no dedicated system for loading [preighters], most of the process must be completed manually by airline or airport staff. In some cases, this can take a significant physical toll on ground handling agents.”

Now, all you head-shakers and uh-uh men who say that the airline bosses wouldn’t go for a fleet of airliners that can be rapidly switched to freight: Well of course not! They could never be inspired to do such a thing out of concern for humanity, any more than they could be shamed into doing it.

But if you incentivize them with cash, they’ll bustle right along with you. Start with the companies that build and refurbish airplanes. Commission them to come up with designs for building/rebuilding big, medium, and small airframes, specific models now on the market and in service, to preighter use. Examine, critique, and revise the designs. (You’ll utter those terrifying words, “I’m from the government, and I’m here to keep you honest.” But since you’re paying the bills, that’s reasonable.)

Now comes the cash-heavy part: The builders of airplanes must agree to produce one preighter aircraft for every – what? five? ten? twelve? common garden-variety airliners – using the usual tax breaks and bonuses that alone work to persuade capitalists. Similarly, the airlines must agree to buy and fly these planes, which after all won’t differ mechanically or operationally from others until an urgent public need for air freight arises. Then, these specialized machines will be subject to leasing by the authorities tasked with responding to

to the Chernobyls, Covids, Christchurches, tidal waves, volcanic eruptions, impact events, and human beastlinesses that we all know will occur.

Expanding and adapting ground facilities for loading and unloading cargo should prove no great problem, because so much already exists. Needless to say, design and manufacturing of such equipment can be boosted along with subsidies, and infrastructure again leased at need.

I specify leasing, because the bosses must feel sure of not losing any money on this deal. See? I understand capitalists just as well as you do.

 

[Ziggurat]

Tend to think Ziggurat is correct but has anyone cited how much of an increase there was during the pandemic?

From what I can tell, demand actually dropped during COVID. The challenge seems to have been that COVID also negatively impacted capacity.

 

[Ziggurat]

Then, these specialized machines will be subject to leasing by the authorities tasked with responding to the Chernobyls, Covids, Christchurches, tidal waves, volcanic eruptions, impact events, and human beastlinesses that we all know will occur.

That doesn't actually make sense.

Here's the wrench in your plan: in any of the (real) emergency situations you list, the limiting factor isn't going to be the number of freight-capable planes. The limiting factor is going to be the air fields that such planes can land in, and their capacity to handle that air traffic.

 

[theprestige]

Here’s what I should’ve done first:

https://en.wikipedia.org/wiki/Preighter

Two passages from this article that struck me:

“Prior to the precipitous drop in air travel caused by the outbreak of COVID-19, cargo capacity in the belly hold of passenger aircraft accounted for half of global air freight, rising as high as 80% on transatlantic routes.”

“As there is no dedicated system for loading [preighters], most of the process must be completed manually by airline or airport staff. In some cases, this can take a significant physical toll on ground handling agents.”

This confuses me.

Passenger airliners have capacious cargo holds underneath the passenger compartment. Some of that space is occupied by passenger luggage, of course. The rest by freight.

And there is absolutely a dedicated system for loading the cargo holds of passenger liners.

So what's the actual claim here? That the demand for vaccine shipments is so large that it has saturated both the dedicated cargo carrier market, and the cargo-carrying capacity of passenger airliners? That after using the normal systems to pack the holds full of vaccines, including the space not occupied by passengers who aren't flying these days, there's still so much vaccine left over that flight attendants have to lug it into the passenger compartment and strap it into the empty seats? Maybe throwing out their back in the process?

Seems like a cheaper solution would just be to pull a few passenger liners out of rotation (since demand for passenger travel is down anyway) and dedicate their entire cargo hold to vaccines, which are loaded in the usual way using the existing dedicated systems.

Or, hell, even commandeer a few dedicated cargo planes to ship vaccines. Let people wait another week or so for their Amazon shipments. There's your convertible freighter solution.