Aircraft Comparison
I'm seeing the "get an AN-2" suggestion floated a bunch, so I went on an obsessive wikipedia binge and have resurfaced bearing information on useful transport/cargo aircraft. This all basically assumes low and slow is all we need, and a multi-purpose utility aircraft with good rough field performance is what we are looking for. This is not to say that something like this should be our highest priority, just trying to figure out what our best options are if we want to go down this road. In practice, what we can or can't actually get will probably be as much about GM rulings as our preferences, if not more.
The AN-2 has a lot to recommend it. It's an excellent largeish bush plane, well suited to short, unimproved runways and remarkably rugged. Not all that widely available in Africa, but that's a surmountable problem. 12 passengers, which is certainly enough to be useful. No ramp or large cargo door, which is unfortunate.
Some other good candidates:
AN-14: Tried unsuccessfully to replace the AN-2. Seats 8. Good STOL performance. Rarer than the AN-2, and very few in Africa.
BN-2 Islander: A utility and transport aircraft with room for 9 passengers widely used as a regional airliner. Decent STOL performance and can operate off of a fairly rough runway, but not really a bush plane. Freight versions exist. They seem to be reasonably common in Africa.
DHC-2 Beaver: An absolutely legendary bush plane, mostly in the context of Alaska and Canada. Some variants will seat up to 11, but most seat more like 7. Can carry 2000 lbs, and has good sized cargo doors (for a plane its size) on each side. Excellent STOL performance. There are some in Africa, with both military and civil operators.
DHC-3 Otter: A fine bush plane, though seating one or two less than the AN-2. Not too widely used in Africa, but more so than the AN-2. Think beaver, but a bit bigger.
DO-28: A twin engine STOL utility aircraft with only 7 passengers, so a bit smaller. There seem to be plenty in Africa, but mostly military.
Noorduyn Norseman: A bushplane with seats for 10 passengers and similar characteristics to the otter. Very few if any in Africa.
PC-6 Porter: A utility aircraft with 10 seats with good STOL performance well suited for rough, unimproved airstrips. There are only a few operators in Africa, all of them military. A trapdoor can be installed in the floor of the cabin, which is typically used for supply drops or mounting surveillance equipment.
If we want to go smaller, we're looking at something for observation, smuggling small quantities of something or transporting one or two people, rather than a real cargo or transport aircraft. Any decent bush plane will get the job done, so whatever will blend in locally is probably best. Pretty much any of the small aircraft people associate with Piper or Cesna will do the job well.
If we want to go a little bigger:
AN-28 and PZL M28: A stretched AN-14 with various improvements. Seats up to 19. Good STOL performance. At least some versions have a rear cargo ramp. Fairly rare, but some are in Africa.
C-212 Aviocar: An STOL cargo aircraft and short-haul airliner. Passenger versions seat up to 28. Has a cargo ramp and is well suited for skydiving. The US Army Special Operations Command and Blackwater apparently like them for many of the tasks we might use them for. There are a number of military operators in Africa (including Zimbabwe), but no civil ones as far as I can tell.
DC-3 / C-47 Skytrain: Designed as an airliner, but in the 30s that meant sometimes operating off of what we'd consider a pretty bad grass strip today. The oldest aircraft in large-scale operation, with over 2,000 in active use today. Legendary for ruggedness, reliability and versatility. Needs a bit longer to land than most on this list, at least under sub-optimal conditions. Seats up to 32. No cargo ramp. There are plenty of them in Africa, so they ought to blend in and parts will be available.
DHC-6 Twin Otter: A nice plane for short fields. 19 to 20 seats. No cargo ramp. Reasonably good for parachuting. There are a decent number in Africa, but not the most common aircraft there.
DHC-4 Carabou: Good short field performance and does fine on a grass strip. It's got a cargo ramp, and it can carry 32 troops, 24 paratroopers or two jeeps. There aren't many civil operators in Africa, but there several countries that will have just recently phased them out of military service, so they may be available. Not an especially quiet aircraft, and rare enough to be a bit distinctive.
DHC-5 Buffalo: Essentially a slightly expanded turboprop version of the DHC-4, with notably higher cargo capacity and apparently somewhat worse STOL performance. Not as widely available, but there are a few in Africa.
SC.7 Skyvan: 19 seat STOL aircraft normally used for short-haul freight or skydiving. Not that many around. It has a cargo ramp.
Short 330: A stretched SC.7 that seats 30. Most are built as airliners and don't have the ramp, but there's a cargo variant that does. Good short field performance, but probably not as good. Rare, and none in Africa.
Short 360: A slightly expanded Short 330 that seats 39. Also has a cargo version with a ramp. Probably has a little worse STOL performance. More common than the 330, with a couple in Africa.
If we want to go significantly bigger:
AN-24, AN-26, AN-32 and Xian Y-7: Closely related STOL airliners and military transports. They seat in the range of 40 to 50. They are good at short, unimproved fields by the standards of an aircraft their size, but don't expect them to take off quite as quickly as a Beaver or an AN-2. AN-24s and most Xian Y-7s are configured purely as transports, but AN-26s, -32s and some Xian Y-7s have a cargo ramp. AN-24s are reasonably common in Africa, AN-26s have some presence in mostly military operators, the others not so much.
AN-72 and AN-74: A turbofan powered replacement for the AN-24 and derivatives. Similar characteristics. All (or those not configured as airliners?) seem to have a cargo ramp. 52 passengers or 10 tons of cargo. Very good STOL performance for an aircraft its size. There are a few in Africa with both military and civilian operators.
DHC-7 "Dash 7": An STOL regional airliner that seats 50. No provisions for large cargo. Performance not far off from bush plane-like, supposedly. There are a few in Africa, but not common. 4 engine, so extra complexity, and the engine out performance is notably mediocre. Relatively quiet.
If we want to go a
lot bigger:
IL-76. A soviet strategic airlifter that also sees a ton of use as a civilian cargo plane. Able to operate from relatively short, unpaved runways, but will still need more than the rest on this list. There are a bunch of them in Africa, many of them civilian. This is what we want if we need to fly a tank somewhere.
Edit: Added a couple more.
Edit 2: For questions about capacities on the larger end ("Can an AN-72 carry a PT-76?", etc. (answer is no.)), see this document:
http://www.jofair.com/news/archives/2003-Freighter-Reference-Guide.pdf
Edit 3: a minor correction.
Edit 4: a correction on which AN-24 and AN-72 derivatives have cargo ramps.