The L-410 Turbolet by KSGY is available on x-plane.hu for free. It’s real world counterpart is a Czechoslovakian high-wing, short-range, twin turboprop that is most flown in the Eastern Hemisphere for passenger and cargo operations.
The Turbolet’s exterior modeling is really nice. It matched all of the images I could find and the developer even nailed some of the smaller details like the pitot tubes, exhaust pipes, static wicks, and antennas. There are a few details that could have been better like the shape of the cockpit windows. But, for free, these things aren’t anything worth griping about. Besides, you should spend a majority of the time in the cockpit anyways.
The Turbolet's interior modeling also is very accurate and detailed with gauges, panels, and systems all included in the mesh and not just baked into a flat texture. I was actually very impressed with the resolution of the UV mapping. This helps out a lot with texture resolution and clarity. Another thing worth noting is that the aircraft includes a cabin. Personally, this makes no difference for me (unless it affects frame-rate), but for those that appreciate a cabin, it's there.
The textures on the Turbolet are overall really nice for a freeware aircraft but they could be better. First off, the base is really nice. The colors are very accurate and match the real world counterpart. The labels and overlays were the same too. Next, the texture weathering, erosion, and wear and tear is nice but overdone in some spots. A good example is the exhaust smog on the wings. It is way overdone on top of the wings. I couldn’t find a single image that even remotely resembled the smog in sim. The rest of the aircraft is actually quite realistic though in this area. As for the PBR, overall the aircraft is quite nice. The bump mapping is very nice and reflections are alright too but my biggest gripe in this area is the lack of metalness. For example, the exhaust pipes on the engines look very wrong and so does the landing gear mechanism. Lastly, the developer did a great job with his use of color burn and other blending techniques. The liveries that are included really shine because of this.
The interior textures on the Turbolet are also quite nice. Some things that I really liked to see were the reflective instruments and glass covers, the wear and tear, and the ambient occlusion. From the images I’ve seen, the cockpit of the Turbolet comes in many configurations but in this configuration, the textures are very accurate and certainly do the model justice.
Here's a brief overview:
The sounds are overall pretty decent. FMOD is not used and lots of the sounds are default. In the future, I’d love to see the integration of a 3D sound system (like FMOD). A turboprop like the let would really benefit from this because of the unique sounds dynamics turboprops bring (like beta). In my opinion, the best part of the Turbolet’s sound system is the custom GPWS sounds. According to several videos I found, these are realistic.
Here's a brief overview:
The systems, except for a few basic lua scripts for switch and rotary knobs, are all default so I don’t have much to say about them. In the future, I’d love to see the multifunction display work and perhaps some custom electrical work too.
There was really not much documentation I could find on the Turbolet so I can’t critique the flightmodel very much. All I can say is that the engines seems to spool up a bit quick but the aircraft did perform as per the climb gradient and fuel consumption chart in the manual.
According to a Turbolet pilot report on Aviation Week, “engine driven pumps supply the 2,100 psi hydraulic system that powers the anti-skid wheel brakes, along with the landing gear actuators, nosewheel steering, roll control assist system, flaps and ground spoilers” (Aviation Week Network, 2013). Because of the hydraulic assisted control system, this should mean that the airplane should handle quite easily, but not responsively since hydraulics aren’t the most responsive. This was mostly the case but I think the controls are still a bit too responsive. In all though, the handling is probably as good as you’re going to get on the freeware side of things.
For free, this aircraft is great. I’d highly recommend giving it a try to see if you enjoy it. While it's certainly not a super accurate simulation, it is, without a doubt, up to par with many of the lower end payware addons like the Cremonsoft A310, Magknight 787, and Carenado Aircraft and is even better in many categories. The L-410 Turbolet can be found here.
This mod on x-plane.org makes it even better.