Would a piston or turbine engine be best suited for a small UAV flying 8000miles?

Question

I am trying to devise a concept that would airdrop medical supplies around remote regions of Africa: vaccines, medicine, blood... etc. I image the payload would be anywhere between 1-2 ton. I think a UAV would make the most sense because then you don't need to worry about flight-time, speed, pressurization, bathrooms and pilot logistics.

Range is an issue because I might need to determine where to set up runways. Africa spans thousands of miles. Ideally, 8000 miles would be great because you can take off from Europe or Egypt or Israel , then fly anywhere in Africa and return without landing to refuel. But landing at a hub to refuel would double the distance -or half the required range.

Payload weight is something I think about a lot and I need to do more research. Like, how light can you make vaccines? There would also be the syringes and other medical supplies. Also, because of the cold-storage cooling and parachutes I think 1-2 ton is a good estimate.

I was looking at electric powered options and these aircraft are typically short range and expensive. Unless you look at the Impulse 2 which has infinite range, but was $128 million to develop.

So in short, long range, light-ish payload, speed doesn't matter and as cheap as possible.

Answer 1

Not to burst your bubble, but doing this "cheap" isn't possible.

First look at range. Light aircraft that have a 2-ton+ payload have limited range, look at the upcoming Cessna 408, it can carry 3 tons but only has a 1,000 mile ferry range. In order to increase the range, you need to carry more fuel, reducing your load. So lets say you dedicated 1 ton to a fuel tank (neglecting the weight of the tank/piping), that gives you an extra ~300 gallons, maybe an extra 500 miles (I don't have info on fuel burn rates at this time, just a generous guess).

Now, you want 8,000 miles, so you need something that can carry a lot of fuel. Now you're in the 767-ish sized territory, so payload won't be a problem, nor will range (when you add , but it will be expensive. A new 767 cost around \$100 million, or you can lease it for between \$600,000 and \$650,000 per month.

If you need an aircraft with air-drop capability, now you need to find something ex-military. A C-130 won't do (range is only about 2000 miles), even the gigantic C-5 Galaxy only has a 4,800 mile range. There just doesn't exist an aircraft to do this.

Add on top of that the cost of developing an autonomous flying system with take-off and landing capability, you are well into the $200 million range at this point.

So now what? You've got a 767 with large payload capability (but no air-drop) that can fly somewhere and back. Time to fly right? Nope! You now (and have been for some time) need to deal with regulatory requirements for multiple jurisdictions since you are crossing a lot of unrelated airspaces in your flight. You need to coordinate demonstration flights and paperwork, along with all the compliance needed for a "one-of-a-kind" aircraft. Many won't want you flying over populated areas, or may deny you completely. Might have to do some lobbying ($$$).

Ok... got it, regulations approved, flight approved, aircraft bought, cargo bought, time to fly? Almost, try getting insurance. It will be expensive, probably hundreds of thousands per month.

A flight crew is the least expensive thing here

If you are serious about this, save yourself \$100m to \$150m and hire a qualified crew. You don't have to go through the development of this automated system, the regulatory approvals, the test flights, the insurance costs, the reluctance to have a 90+ ton aircraft flying without any operator intervention at 500 miles per hour and just hire somebody to fly it.

Pilots aren't the most well-paid, but lets say you have 2 crews making \$100,000/year each ($400,000/year total) with benefits. That's \$33,333/month, for the cost of development (lets say \$100m) of the automation system, you can employ these people for 250 years.

Answer 2

As others have pointed out, the range you're thinking of is unrealistic.

There are other problems too: making sure your dropped load doesn't hit anyone and will land in the right spot (and not, for instance in the nearby swamp) is not easy.

And in regions remote enough to qualify for this service, you can't count on qualified personnel to be available to receive and use medical supplies.

Have you looked at the way this is being handled today? Organizations like Mission Aviation Fellowship use general aviation aircraft like the Quest Kodiak and Cessna Caravan to fly personnel and supplies to remote locations.

Answer 3

There is no shortage of air freight companies that can quickly ship cargo to nearly any airport in the world, and since they have economy of scale and lots of experience dealing with regulators, you will never beat their costs.

Africa's main logistics problem is the so-called "last mile": getting supplies from an airport to where they're actually needed. In most cases, the range is only a few dozen to a few hundred miles (which could take days by truck, assuming you don't get robbed or killed) and the weight for any individual shipment will be fairly small as well. These trips could be entirely domestic, which makes them much easier from a regulatory standpoint. And it's only when flying such short, light trips that pilots become a non-trivial part of the cost.

So, to best solve this problem, you need a fleet of small and much less expensive drones, with a few at each major airport in each country, plus some staff to load and refuel or recharge them. And that is a much easier mission than what you proposed.

Answer 4

The best aircraft for your job is a used Boeing 767.

As others have pointed out, a UAV the likes of a MQ-9 or RQ-4 costs at least $200M and comes with a small payload and regulatory problems as well. Fortunately, there's a much better and cheaper option. In a 2015 article, Business Jet Traveller suggested a used Boeing 767 as a cheaper alternative to large business jets.

For well-heeled individuals (see below) who worry less about fuel costs, though, the 767 can offer a lot of aircraft for a relatively low price. [...] You can pick one up in airline configuration for as little as \$9 million, and that’s a pretty good deal for a big—and I do mean big—airplane that can fly 8,000 miles nonstop at a top speed of 469 knots. (A new 767 with an airline interior will set you back $185 million.)

They included a detailed cost breakdown, which can be summarized as follows:

Direct operating cost           $14k/h
Annual fixed operating cost     $1M
Annual deprecation              $1M
Total cost at 500h/year         $20k/h

If you buy a used 767 for \$9M, sell it a year later for \$8M, and in the meantime you fly a 10h mission per week where you drop 10 tons of cargo, you will end up with a total cost of \$10M for that year or \$20k per ton of cargo.

The 767 has a much larger cargo capacity, but you have to drop it somehow. I assumed you will carry a 50kg bag on each passenger seat and the crew drops these bags out of the door manually. You have to charge \$1000 per bag to break even. If you fly shorter missions out of port cities in Africa (Cape town, Lagos, Mombasa) you can reduce the cost per bag to \$200-500.

Answer 5

I remember reading about how much trouble it was for those people trying to get permission to fly a balloon across various countries in their around the world attempts. Trying to get the permissions for a UAV of sufficient size to do something like this would be even more difficult.

Assuming the various flight permissions from the various countries could be acquired, you might want to consider an airship (e.g. Goodyear Blimp, Zeppelin, etc) instead. Speed is probably not critical here, so a slow moving airship would probably be acceptable. You would still be better served with a manned crew instead of trying to make it autonomous.

On the other hand, doesn't UPS and FedEx deliver everywhere? :)

Answer 6

Your best bet might be the Aurora ORION UAV. It's essentially a twin engine plane turned motor glider. It offers a payload of up to a ton with a range of up to ~5,000 km. Or a ferry range (no cargo, just fuel) of 24,000 km. Being a glider design, its long distance cruise speed is below 150 km/h. So a long distance flights will take many days.

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What you're looking for is essentially to combine several goals each require more fuel: Distance and load. With a given fuel capacity, stretching either will reduce the other. And both targets (8000mi, 2 t) are each for its own already hard to reach. While business jets like Embraers 300 Series or Pilatus PC-24 come close in carrying capacity, their range is way below 2000 miles. So if at all, it'll take a (small) commercial airliner like an ATR-42 in a special, maximum distance configuration. That's a 50 seat plane with a price tag of about 20,000,000 USD - just the plane. Any drone with the specs you want won't be any less.

So in short, long range, light-ish payload, speed doesn't matter and as cheap as possible.

1-2 tons ist not anywhere 'light-ish' in aeronautics. And for sure not cheap. Especially not when asking or record distance/duration.

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Additional points that come up would be

Pressurisation - While you may think you can go without, your medical supplies can't, they are packaged for a certain air pressure range. Not only do you want the pills to be plopped out from their blisters, blood spilled from their tubes and vaccines floating in their outer containers might be equally undesired. Pressurisation is more important for fright than pilots. Humans can always go for personal gear providing oxygen.

And no, flying low isn't an alternative, as drag at low altitude will cut maximum distance a lot. There is a reason jets scratch the ozone layer in every flight - less air, less drag. Without going up there modern long distance flight would be as well impossible.

Flight Path - Sure, on the map it's easy to cross from Alexandria all the way to some remote town between Bangui and Kisangane. In reality each flight will be more paperwork than filing taxes for a multinational corporation. Each country on the way wants to have their say - and some even change their mind after everything has been signed. Keep in mind, each and every one of them has the means to simply pull your drone off the air.

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Long story short, if this is really ment to work, go for a reasonable concept of medium distance (<1000km) flights with adequate load and managable handling.