An exercise in testing the limits of design
Introduction
Written by Aaron "Ribbon-Blue" Mendoza
Back on September 19th, 2024 I had talked about how a particular demo from Steam Planes, Trains and Automobiles stoked my interest in finally trying out a design and fly aircraft builder game from start to finish. Granted, at this time it is a demo, but I had said I wanted to give myself some more time with the title before writing more about it.
Aviassembly is the second commercial game project by Jelle Booij, a developer from the Netherlands. Curiously, his first commercial project was Taste Maker, a game about building a restaurant from the ground up and managing it to success. Everything from the decoration of the building, quality of food and cleanliness of the restaurant was factored in. The success of Taste Maker is what pushed the developer to launch their full time indie game development career. Jelle started development of Aviassembly in May 2023 with the Steam page launched on February 2024 and the first iteration of the game’s demo available to the public on September 16th, 2024. As of the time of this article’s release, the demo has received two updates.
Do keep in mind that this game is still in development. A lot can change between now and early 2025, especially with the input of anyone playing the demo. The developer is very open to feedback and requests on the Steam Forum and official Discord server. There are many additions and changes being applied to the game that are not quite seen in the demo yet. Do be sure to make your opinions and requests known.
As I mentioned in the composite article in September 2024, normally I would refer any aircraft builder games/simulators to our resident aeronautical engineer. And guess what? He briefly heard a mention of a new builder on the scene and he jumped in immediately!
The Journey
Written by Caio D. "Hueman" Barreto
As long-time readers will know, I have a particular predilection for "Build & Fly" games; having spent more time than I'm willing to admit in SimplePlanes, I found Aviassembly's core concept - adding an actual mission, cargo transport, to guide your design objectives - a very interesting proposition and was eager to try it out.
Immediately upon attempting to build my first aircraft, however, I was faced with the first hurdle: Unlike SimplePlanes or Flyout, the in-game builder does not allow the player to change the size or shape of the wings. Instead, it takes the KSP approach of offering a selection of pre-made parts; fuselage sections can be stretched and tapered, but apart from that, all parts have strictly fixed sizes.
Not a huge problem; being unable to fine tune your wing size is a bummer - and major constraint - but hardly unworkable; We did routinely build aircraft in Kerbal, after all. However, in its current demo version (and this must be emphasized), Aviassembly lacks the flexibility of KSP when it comes to placing your parts. Position fine-tuning is non-existent, and angles can only be changed in increments of 90 degrees.
The game decides how it wants the part to be attached - usually, orthogonal to the attachment surface. This means that, if you wanted, for instance, a high wing with anhedral - a staple of basic aircraft design - you're out of luck, at least without resorting to considerable subterfuge.
Even after employing the aforementioned subterfuge - playing around with finding specific spots and rotations to "trick" the editor into accepting otherwise unattainable part placement - I was still unable to get rid of the game's forced dihedral in a high-wing configuration.
Combined, these current limitations of the aircraft builder means a player’s ability to choose their aircraft’s configuration is severely hampered. It can also lead to hilarious results anytime something slightly out of the ordinary is attempted, as will be demonstrated in this article.
Adding to the challenge is the game’s very purposefully designed constraint system: Players start out with a limited amount of researched parts, KSP Campaign-style, and also a tiny budget with which to actually purchase parts to build their aircraft.
Now, let me tell you how much I absolutely love this concept: Players must design an aircraft capable of accomplishing a mission - usually transporting a set amount of cargo from point A to B. However, in order to do so they must balance:
Available cargo volume;
Lift (from preset wing choices) and drag;
Choice of powerplant;
Fuel quantity and consumption;
Overall weight, which increases with all of the above;
And most importantly, cost.
If the above list looks familiar to you, it's no coincidence - these are all key considerations in aircraft design. But the star of the show here is cost.
Cost is the great constraint which drives challenge in this game. It keeps players from taking the easy approach, and adds in a little bit of those real-life aircraft design challenges that scratch the problem-solving itch in your brain.
In sandbox-oriented games such as SimplePlanes, it is all too easy to solve problems by simply bolting on more stuff. Not enough thrust? Just slap on one extra engine. Not enough fuel? Make the whole thing larger. And while it can also be fun to conceive hilariously oversized aircraft, try convincing an airline to buy a slightly more fuel-hungry jetliner; there's a reason the trijet era is over.
Of course, Aviassembly is not the first in its genre to include a cost calculation; but more often than not in such games, cost is merely another number for your creation’s stat sheet. The touch that sets Aviassembly apart is combining that cost and other limitations with a set of missions to be accomplished. In other words: we have our design constraints, and we have our design requirements - this is the very core of what aircraft conceptual design is all about!
Starting off, you have very limited resources, both in terms of credits and unlocked parts. The only wings available to you are small, flimsy and appropriately named “biplane wings”, so I immediately set out to create the most conventional-looking biplane I could.
However, remember the limitation with part placement? Yeah.
Oh. Oh no.
Building a simple biplane - one with reasonably positioned wings, at least - was a herculean task. Eventually I settled for pulling a card from the Transavia Airtruk’s playbook - choosing the enclosed cockpit part, I positioned the upper wings around the cabin, resulting in a workable, but quite funky airplane.
Looking at my unsightly, yet adorable creation, I decided “Scrunklo” would be an appropriate name. And thus, the newly christened Scrunklo Mk. I took to the skies. It flew, and handled reasonably well - however, flying an airplane for the first time in this game made me acutely aware of a few issues.
The first was that there is absolutely no thrust modulation. The engines have three possible states: full send, off, and full reverse. The second issue was that said engines consume fuel at a prodigious rate, meaning that your time on the throttle is measured in seconds.
This means that, to get anywhere, one must apply “blips” of power and then effectively glide the rest of the way, which feels extremely wrong and uncomfortable if you're used to how aircraft engines are supposed to work. To add insult to injury, there are no brakes in this game - the only two things that can stop you on a runway are regular friction and full reverse thrust. So, a deadstick landing means severely degraded braking distance.
In Aviassembly, you'll likely be doing a lot of your flying with the engine out. Ouch.
After getting used to treating my little prop-engined biplane like an Me 163 Komet, I was soon faced with my first task: to deliver two crates of medicine (two units of cargo) to a nearby airport. The Scrunklo Mk. I was perfectly capable of doing just that, though its painfully short range meant I had to hop between each and every airport for longer flights.
Soon enough, however, the tasks started requiring more and more cargo to be delivered - and no, you cannot deliver them in two flights carrying half each. Naturally, this led to the stretching of the fuselage to make room for more cargo, resulting in the Scrunklo Mk. II.
This aircraft suffered from two main issues, though: when fully loaded, it would struggle to take off, and needed to be flown at a much higher speed. This meant more fuel consumption, and therefore a fully loaded Mk. II could only barely make it between most airports.
Clearly, a complete redesign was in order - I had reached the limits of what this biplane design could offer. Thankfully, the completed missions allowed me enough research points to unlock new parts - I invested in new wings, external fuel tanks (the only way to increase fuel capacity in the game) and a new cockpit, which carried 4 cargo units by itself - a significant boost in capacity which would otherwise have required a much larger fuselage.
Aerodynamics in Aviassembly are modelled in an extremely simplified manner; you're not going to be talking about Cl or Cd anytime soon, and reference areas do not exist as it's impossible to choose wing area to begin with. However, each wing part comes with its own fixed lift and drag “values”, which allows one to deduce the lift-to-drag ratio for each choice. Each new wing you research offers a substantial increase in L/D. This was exactly what I needed - except this is accompanied by an equally significant increase in cost. As it turns out, after equipping the new wings and cockpit I barely had enough funds left. To make matters worse, since the new cockpit was a nose piece, a nose-mounted engine was not an option - I chose the traditional twin-engine, wing-mounted layout, but after adding the cost of two engines, I had almost nothing left for the fuselage.
The result of this ordeal was the one and only Twin Scrunklo Mk. III - or as I prefer calling it, The Egg.
Straight out of an eggplane model kit!
This super-deformed caricature of an airplane actually performed extremely well in-game - way better than it had any right to. It performed so unbelievably well, in fact, that even after getting more funds, I chose to upgrade it instead of going for a clean sheet design.
Thus, when funds allowed for a slight extension of the fuselage and extra fuel tanks, it was turned into the Twin Scrunklo Mk. IV, with two extra cargo unit capacity - and after researching brand new engines with the funds acquired from the Mk. IV's successful operation, the Twin Scrunklo Mk. V was born.
With more power, extended range thanks to four extra fuel tanks, and a whopping cargo capacity of 9 units, the Mk. V was the pinnacle of my Aviassembly experience. It handled beautifully and had more than enough performance to carry me through most of the playthrough. I regretted only that the game did not offer retractable landing gear, leading to the fixed gear ruining the Twin Scrunklo's clean, egg-shaped lines.
Look at how adorable it is!
At this point, a new mission popped up - to bring glass from the desert. Now, the desert is a far away place in Aviassembly, hidden behind a vast expanse of ocean - attempting to traverse it with any of the previous aircraft would have been pointless (remember, endurance measured in seconds), but now, I finally had an aircraft with a range up to the task. If there was one machine that could do it, that would be the Twin Scrunklo Mk. V.
So I pointed my aircraft towards the distant desert and began my journey. The Mk. V would have had enough fuel to reach its destination - but alas, the area is out-of-bounds in the demo. Upon approaching it, one is greeted by a warning telling you to turn back or else - curious as always, I kept flying until my aircraft was expeditiously disassembled, but not before I got a glimpse of the coastline off in the distance.
I wonder what happens when that timer hits zero...
It would obviously not be possible to complete that one task - but there was still more to be done in the accessible map area. I was determined to finish every single possible task, and so I got to working on the next goal: transporting 12 cargo units.
All good things must come to an end; and so it was that I no longer had funds to further stretch the Twin Scrunklo to a point where it could've carried 12 cargo units. I had to eliminate cost elsewhere in order to be able to afford a larger fuselage - and the engines were by far the most expensive part.
If I could use a single engine, there was comfortably enough room in the budget for a 12-unit fuselage. However, I was still using that nose cockpit with its sweet 4 cargo capacity as a freebie, so I could not mount the engine on the nose. The obvious solution was a pusher configuration.
However, upon rolling the Push-Scrunklo Mk. VI to the runway, I was hit by a shocking realization: Aviassembly uses the engine as the aircraft's directional reference, not the
cockpit.
This is the default camera view with a pusher configuration aircraft.
This meant that the camera was facing backwards, but even worse, all controls were inverted. To go forward, I had to apply full reverse thrust and fly "backwards". Flying this way was obviously an unreasonable proposition, and thus with a heavy heart I had to abandon the pusher concept.
At this point, I was at a loss. How was I supposed to use a single engine if I couldn't mount it on the nose, didn't have any pylons I could mount it on, but also couldn't use it in a pusher configuration?
Of course, there was an answer. There always is. I felt cheated by the game, taking away such a basic design choice; but there was another way to look at it - as just another design constraint.
Incidentally, I have spent the last handful of years in university learning to work with strict and sometimes unusual aircraft design constraints. Undeterred, I went back to the drawing board and told myself:
Unreasonable constraints require unreasonable solutions.
And thus, the madness began.
I hope Burt Rutan would be proud of me, because I'm really not.
Enter the Scrunklo Asimetrico Mk. VII. By choosing an asymmetric configuration, it was possible to employ a single engine in a tractor arrangement, with plenty of fuselage volume for cargo to boot. Takeoffs were difficult due to the far off-center engine - again, being unable to resize wings was a major hurdle here, forcing the two fuselages to be way far apart - but otherwise, the plane handled just fine in the air.
However, when fully loaded with cargo, the underpowered, heavy and draggy airplane struggled. It responded sluggishly and was extremely slow; and though it was able to complete one of the 12-cargo missions, it lacked the range for the other one.
Further out-of-the-box thinking was required. Fortunately, giants of the past allow us to see further by standing on their shoulders. Of course! The Trislander! I exclaimed in joy. The Trislander has one of its engines mounted directly on the vertical tail - that was the solution to my problem.
By employing a tail-mounted engine, the Scrunklander Mk. VIII avoided its predecessor's asymmetric thrust, and by concentrating its cargo in a single, wider fuselage, enjoyed a great reduction in weight and drag. The far smaller number of parts used also lowered cost, freeing up the budget for the acquisition of extra fuel tanks.
The Mk. VIII flew a lot better than it arguably should have, and completed the other 12-cargo challenge thanks to its extended range. Now, only the two final challenges remained - after these were done, I would have officially completed every single possible challenge in the demo.
The final challenges consisted of delivering 15 wood and 12 apples to the Hospital on the far south of the map. The wood wasn't a huge problem - even though it can only be sourced on the northwest, one can easily design an aircraft solely focused on payload and compensate for its short range by "hopping" between airports along the way for refueling stops. For this purpose, it was sufficient to employ a conventional configuration; one so conventional and reasonable in fact, that it did not feel like a continuation of the Scrunklo series. Therefore, it was christened the Transportador Mk. I, and apart from the minor inconvenience of having its landing gear collapse on landing when fully loaded, it was an otherwise trouble-free aircraft.
The apples, however, are a different story.
Apple delivery missions are essentially time trials; as soon as you pick them up, the clock starts ticking. After the timer reaches zero, the apples go bad and can no longer be delivered.
There is only one source for apples in the currently available map - a farm on the far northeast - and apparently, instead of picking their apples, they prefer waiting for them to drop to the ground instead, as the time before they rot is measured in seconds. Compounded with the fuel limitation hindering full throttle use, this makes apple deliveries truly challenging.
My beloved Twin Scrunklo Mk. V had carried me through all other apple delivery missions so far, but it would no longer be enough this time. I needed something extremely fast, with 12 cargo unit capacity (33% more than the Mk. V!), and with enough fuel to fly from the far north to the far south of the map non-stop. And I needed it within budget.
I needed something radically different.
A wise man once said that airplanes are beautiful, but cursed dreams. I disagreed on the last part; Aviassembly proved him right through my own hands.
Gaze upon the Scrunklo Mk. IX - the ultimate apple delivery machine. With two wings arranged in a tandem configuration, a long fuselage capable of holding all the apples you could ever need, two powerful engines and enough fuel to enable this contraption to cross the entire map without ever needing to stop for refueling - and almost without letting off the throttle - this ugly ducking was my ticket to the swan song of this demo.
Almost there... Notice the timer on the bottom right.
Apples delivered in the nick of time!
The Mk. XI had worked far better than I had ever anticipated, and I had reached the demo's end. This was it - there was nothing else to be done.
Or was there?
See, as soon as you complete these two big deliveries to the hospital, the game bestows upon you enough research points to unlock all available parts - and, crucially, with enough credits to be able to build essentially anything you want.
And when I realized the possibilities that lay before me, I thought back to that desert.
Sure, it was pointless to try to complete the forbidden glass pickup mission. The area was clearly off-bounds - even if I managed to land, it wouldn't be possible to take off and leave the area in time. But still, I had seen a glimpse of a coastline, and I wanted to know whether the desert airport had already been modelled or not. No - I needed to know. And therefore, I made it my mission to reach the desert.
It was time to play around with some configurations; at first, I tried a mostly conventional-looking business jet. However, with its thristy turbojets and small fuel tanks, it lacked the range to make it there. And at this point, I had already made so many cursed designs - what was one more?
It was time to go all out. I didn't really need a big fuselage - no cargo would be carried today. Only fuel, an efficient turbofan engine, and the tiniest fuselage possible.
With this configuration, I finally had all the range I could ever possibly need. However, it wasn't fast enough to make it to the desert in time. The solution was obvious: Now that the game was essentially a sandbox, not unlike SimplePlanes, I could use the tried-and-true Kerbal approach to problem solving:
MORE.
THRUST.
Behold the Super Scrunklo Mk. X. This little abomination not only has incredible range, being able to easily cross the demo map without refueling, but is also disgustingly zippy. It should not be allowed to perform this well, but the fact that it does supports my personal theory that eggplanes are the current Aviassembly meta.
You may not like it, but this is what peak Aviassembly performance looks like.
Now armed with this ludicrously overperforming craft, I set out to accomplish my ultimate goal. Lo and behold...
The desert airbase, in fact, exists! And it is fully modelled. It just hasn't been implemented in the game yet.
Naturally, my creation was vaporized by the timer shortly after this print was taken, and I didn't manage to land on the desert runway; but having entertained my curiosity and pushed the limits of the game this far, I was finally satisfied. And thus, the Super Scrunklo was peacefully retired from service alongside its funky, egg-shaped, and asymmetric brethren.
Final Considerations
Unfortunately, as of its current state as a demo, Aviassembly fails to capitalize on its very solid and interesting premise. But allow me to reiterate; the game hasn't been released yet, and the core concept is very, very promising. With some tweaks to the construction system, a few quality-of-life additions, and some parameter adjustments - for instance, reducing engine fuel consumption in exchange for reduced power, allowing players to cruise on continuous power instead of "pulsing" their engines - I am confident this can become a very solid game.
All in all, I had lots of fun trying to circumvent the game's limitations and trying to see just how far I could push it - and what I could get away with. If you're interested in this genre, I strongly encourage you to try the demo out!
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