Aircraft Design

[Destragon]

Designing aircraft is very complex and right now feels a bit like punching random numbers into a blackbox and hoping for the best. So I wanted to start a thread here where I will collect all the information about aircraft design I can find, hopefully making it easier to come up with viable designs.
If you know more information about aircraft design, please post comments to fill in the blanks.

Planetary Statistics
In an ongoing game, you can find these statistics by clicking on Reports -> Help -> Planet statistics overview. At the bottom of that screen you can also find what kind of airplane engine your secretary recommends to use on your planet.

Gravity
Affects the weight calculations of the aircraft, reduces speed and range. You generally want lower gravity for better aircraft, but higher gravity planets tend to also have thicker atmosphere to balance it out.

Air pressure
Decreases speed, but also increases range. It seems that a thicker atmosphere is generally better for aircraft and will be a big factor on determining the range.
The air pressure also determines the speed of sound, which acts as a speed cap for non-supersonic aircraft. The thicker the atmosphere, the higher is the speed of sound.
Rocket engines are special in that they are the only engine type that actually increases range the lighter the atomsphere is. If there is no air pressure at all, aircraft require rocket engines to fly.
Thopters are better when the air pressure percentage (in relation to Earth's) is higher than the gravity.


Aircraft Types
Airplanes - Ultralight, Light, Medium (1 and 2 engines), Heavy (2 and 4 engines), X-Heavy (4 and 6 engines)
Helicopters - Light, Medium, Heavy
Thopters - Light, Medium, Heavy
Helicopters, thopters and airplanes with VTOL engines can land anywhere, but at a reduction of their max readiness. All other airplanes require airbases of increasing sizes.


Aircraft Components
Role
The role determines if your aircraft should flee from air combat as fast as possible and if it should be flying low or high.
Flying low gives better recon, flying high gives less accuracy, but also generally makes it harder to be hit by AA.

Engines
Bigger engines increase speed (up to the speed cap), but they are also less weight efficient and less fuel efficient. If the aircraft is already at the speed cap, there's probably no benefit to increasing the engine size.
VTOL engines allow planes to land anywhere at a readiness penalty.
Helicopters only use rotors.
Rocket engines are required without air pressure.

Wings
Bigger wings increase dogfighting score, range, max weight and reduce minimum takeoff speed, but also reduce the aerodynamics and increase weight.
This means that wings both increase and decrease dogfighting score and I'm not sure if higher speed or bigger wings are better for dogfighting.
Helicopters don't get to choose.

Fuel Tank
Bigger fuel tanks increase range, but also increase weight. Adding a fuel tank that is too big might give no benefit besides reducing range.

Air-to-Air Weapon
Machineguns (mounted and cupolas) give a big malus to the first 2 rounds of air combat.
Mounted machineguns can also be used for anti-surface combat.
MG cupolas can only be used by heavy and extra heavy airplanes and are strictly for air combat.
Air-to-air missiles have the same firepower against surface targets as MGs, but are vastly more powerful against air targets. They are unlocked by the Missiles tech.

Air-to-Surface Weapon
Bombing hatch + bomb are good against structures and soft targets and also give you cargo space, letting you use the bomber in potential air bridges.
Precision bombs have double the fire power of hatch bombs and are better against hard targets. They can't be used by helicopters, nor by heavy or extra heavy airplanes.
Air-to-surface rockets are unlocked with the Rocketry tech. Can only be loaded by light and medium airplanes, helicopters, and thopters.

Cargo Space
Necessary for air bridge missions, but increases weight.
100 kg of cargo space translate into 1 logistics point, but it also gets multiplied by the amount of aircraft in the formation.
The maximum size of a unit model that can be transported via air bridge is the square root of the bridge's average capacity divided by 1000. (For example, if you have an air bridge consisting of aircraft that each can transport 1000 kg, then the maximum size is the square root of 1 -> 1. That would mean only infantry could be airlifted by this bridge. If the average capacity was 4000 it would be the square root of 4 -> 2, which would let you also airlift transport trucks.)


Aircraft Statistics
Most of these stats are influenced by the planet's gravity and air pressure.

Hitpoints
Increased by size and by the Aircraft Rugedness optimisation technology.
Size
Increases hitpoints and the square root of the size determines how many airbase points the aircraft needs for full readiness recovery.
Weight
More weight means less range, less speed and higher minimum takeoff speed.
Speed
More speed means more range and better dogfighting score.
Influenced by engine power, weight, aerodynamics. Capped by air pressure for non-supersonic aircraft.
Minimum takeoff speed
The speed needed for the aircraft to take off.
Influenced by weight, wings, maybe engine?
Range
Range determines how far the aircraft can fly. It's translated from km into hexes by dividing it by 200.
Influenced by weight, speed, wing size, fuel tank.
Operational range is the range aircraft can fly missions at and it's half of the maximum range.
Because of the way range is translated into AP movement cost, the amount of hexes for operational range can only be one of these numbers:
0-12 at 0-2400 km
14 at 2800 km
16 at 3200 km
20 at 4000 km
25 at 5000 km
33 at 6600 km
That means, if you design an aircraft that has a range of 6000 km, it will still only have the same actual hex range of an airplane with a range of 5000 km (25 hexes). Only at 6600 km the range will jump over to 33 hexes. So, you should be aiming for these specific km numbers when designing aircraft, or you're essentially wasting engine power or weight.
Dogfighting score
Having a higher dogfighting score than the enemy planes in air combat will give you a bonus and the enemy a malus.
Influenced by speed, wing size and horsepower to weight ratio.


Technologies
Aircraft/ Helicopter/ Thopter Design - These increase the structural design value of newly designed aircraft model serieses of the corresponding type. "Aircraft" Design only applies to airplanes, despite the name.
Propeller/ Jet/ Rocket Engine Efficiency - These improve the fuel efficiency of the corresponding engine type. Helicopters use Propeller Engine Efficiency. The normal Fuel Efficiency tech also applies to aircraft.
Leightweight Alloys - Reduces the weight of your aircraft designs.
Aerodynamics Design - Improves the aerodynamics of your aircraft designs.
Aircraft Rugedness - Increases the hitpoints of your aircraft designs.
Rocketry - Lets you put air-to-surface rockets on your aircraft.
Missiles - Lets you put air-to-air missiles on your aircraft.


Abbreviations
ENGINE EFF - Fuel efficiency of the engine
HP:WEG - Horsepower to weight ratio
AERO - Aerodynamics
OP RANGE - Operational range in hexes
FIREP - Firepower
Rnd 1, Rnd 2 - Round 1 and 2 combat modifiers

Benchmarks
Vic has shared a useful document showing what kind of aircraft ranges you can expect on planets with certain gravity and air pressure (on version 1.05 beta 19):
http://www.vrdesigns.net/openbeta/analytics_air.pdf
https://www.matrixgames.com/forums/upfi ... 3AC0D4.jpg

[Clux]

Really good "guide", however, till we get the formulas it'll be a headache to make and test models [:(]

[omzh]

Appreciate you putting this together Destragon! I'll definitely reference it when I test airplane designing.

[KingHalford]

Great work sir!

[mroyer]

Great post!
I've been meaning to comment on the design process in SE in general (not just related to air units).

As cool as it is to design your own equipment in SE (as an engineer, I really enjoy that aspect of the game), I think the basic design-flow in SE is backwards. In real life, no politician would ever sit down and specify 25mm armor, a dual-diesel engine, and so on. They don't really care about those technical details. They care about production and maintenance costs vs mission performance.

So, instead of players blindly selecting technical details and hoping for a good result, as national leaders players should be defining mission-critical parameters: we want a tank that can withstand an 88mm hit, has good cross-country performance, requires under 250 metal to produce, uses less than 10 fuel per hex, and whatever, etc, etc...

Then our research director and his engineering staff (via some director technical-capability die roll) try to achieve, or come close to achieving, to those goals as limited their capability and physical reality. The politician (i.e., the player) gets to accept or reject a prototype, when it's available, based on its performance. The politician might even have a "try again" option where the engineering staff can attempt improve on their first design and come up with a second prototype. The director/engineering staff might respond that the politician is asking for the impossible - we done the best possible. Maybe they have, maybe they haven't - the politician has gotta' guess.

Anyhow, IMO, a system along those lines would better model the design process from the perspective national leaders.

-Mark R.

[mroyer]

..

[Soar_Slitherine]

^ I've had thoughts among similar lines. From the perspective of a ruler rather than an engineer, the current design process is backwards: You have to guess which technical details could maybe result in an aircraft with the capabilities you want, next you get to see if your guess was near the mark (but only as regards to some metrics, information regarding other important capabilities remains hidden), then you need to switch stuff around repeatedly to see if a slightly different configuration is strictly superior to your first guess. The current UI also makes that process way more inconvenient than it needs to be.

I'd be okay with just replacing the current UI with an actually decent one that includes all the design options and relevant information on one screen. However, what I think would actually be ideal if I could specify a list of design requirements, like "anti-air missiles, at least 9 hexes of operational range and the best dogfight score possible within those parameters" or "VTOL capability, 1800 kg tranport capacity, the highest operational range it can have and make the aircraft as big as it needs to be", and then have the game offer up a choice between one or more available combinations of components that satisfy those requirements.

EDIT: Grammar.

[Destragon]

I think that's a great thought. Would fit perfectly into the theme of the game. It could be downright funny when you specify some outlandish stats for your desired vehicle and then next turn the model design director comes to you, begging for you to reconsider your demands.

Here is the obligatory link to the Bradley design scene from Pentagon Wars:
https://www.youtube.com/watch?v=aXQ2lO3ieBA

I think someone should make a separate thread about this in the suggestions forum though, because this is still mainly a thread about trying to figure out how the hell aircrafts work.

[battlefield91]

For the designing of aircraft (or other technical equiment) I like the approach "Rule the Waves 2" did with their handling of aircraft design. You have your different Roles (Torpedo Bomber, Dive Bomber, Fighter etc.) and you can specificaly order a prototype and select different priorities (range, firepower etc.). After a few turns you will have the choice of 3 different designs (from different companies) that sometimes are very good, bad or even worse than your previous model. Some indicators like reliability are even hidden or a rough guess (You will get the knowledge later when the design is in action).

Over the next turns (with some luck involved) the company will improve their model with higher speed or better range... So there is always the gamble of trying to further improve your existing design or, when you think the design is on it´s max, to order new prototypes.

[mroyer]

ORIGINAL: Destragon
I think someone should make a separate thread about this in the suggestions forum though, because this is still mainly a thread about trying to figure out how the hell aircrafts work.

Done here.

[Destragon]

Does anyone know for sure if weight increases hitpoints or not?

Also, if you find more unexplained abbrevitations ingame, let me know, so I can add them here.

Edit: Still not exactly sure if weight increases hitpoints, but apparently hitpoints get randomised by up to 50 points, every time. Which means that if you design a new version of your aircraft without any changes, it's possible that the new version will just randomly have less HP. Sounds kinda weird to me.

[Vic]

ORIGINAL: Destragon

Edit: Still not exactly sure if weight increases hitpoints, but apparently hitpoints get randomised by up to 50 points, every time. Which means that if you design a new version of your aircraft without any changes, it's possible that the new version will just randomly have less HP. Sounds kinda weird to me.

Changed this in v1.06.09 Thanks

[Destragon]

Thanks Vic. The change sounds reasonable.
" -Design of Air Models… Hitpoints last formula part is now +25 instead of +1d50. Much more consistent with the rules like this. "
I take that the +25 means that that is basically the base HP of every aircraft design, not that you get free 25 extra HP whenever you redesign an aircraft.

I also added the calculation for maximum unit size for air bridge airlifts into the OP.

[yutowap33]

Designing aircraft is very complex and right now feels a bit like punching random numbers into a blackbox and hoping for the best.

Yes.

[zgrssd]

Some remarks:
It appears that Gravity and Airpressure are part of the Aircraft Design itself - they are referenced in the Design log. So any formula or example has to take Airpressure and Gravity into account!
However the Horsepower/Weight Ratio and Wingload do not actually take gravity into account - the values are the same on the same starting design (1.08.03 beta)

Move Oil under Operational costs seems to be Fuel/Hex * (Range in Hexes -1). The -1 Reduction in hexes might be a mistake, or you get 1 Hex free intentionally.

Fuel Cost/Hex is: [Fuelcost/km as given in the Text] * 200 * 2
So this is the operational consumption, where you have to fly each hex twice (once there and once back).

Some mathing attempts - Horsepower/Weight ratio:
Asuming this does not use the weight modified by gravity (or at least not on the starting desings), i got the following values for starting planes:
1760 kg starting Scout plane using a 150 Engine Power Engine has a Horsepower/Weight Ratio of 23%.
5490 kg starting Fighter plane using a 600 Engine Power Engine has a Horsepower/Weight Ratio of 26%

So Engine Power * X / Real Weight = HP/Weight Ratio. Asuming X is 1:
150*1/1760 = 0.085
600*1/5490 = 0.109

When I divide the Stated HP/W Ratio with the results above, I should get the real value for X:
0.23 / 0.085 = 2.705
0.26 / 0.109 = 2.385

I think I figured out X it is roughly 2.4-2.7:
150*2.4/1760 = 360/1760 = 0.2045
150*2.7/1760 = 405/1760 = 0.2301
600*2.4/5490 = 1440/5490 = 0.2623
600*2.7/5490 = 1620/5490 = 0.2950

Somehow Horsepower seems Engine Power * 2.7 for Ultralights and 2.4 for Light Aircraft

Could anybody test this formula for bigger Aircraft Designs they have lying around, preferably Medium 1e, Medium 2e and Heavy 2e?

[zgrssd]

Lets see if there is any pattern to the Prognosis:
The starting fighter on a 0.33g, 10m/s Windspeed*, 446 mBar Pressure:
Max Weight: 14236
Total Weight: 5490

Prognosis:
Takeoff: 122 km/h
Max Ground: 264 km/h
Max Air: 289 km/h
Range: 4464km
Op Range: 2232km (11 Hexes)

Now the same design, on the same planet, but let us add 3 tons of Laser Guided Ammunition to make a fighter-bomber:
Max Weight: 14236
Total Weight: 8490

Prognosis:
Takeoff: 154 km/h
Max Ground: 207 km/h
Max Air: 226 km/h
Range: 1074 km
Op Range: 537 km

So making a plane heavier increases the Takeoff Speed and decreaes the Max Speeds, while also decreasing Range. That means:
- Sooner or later you hit a point where the design can no longer lift off the ground
- Weight negatively impacts range. Wich implies the Weight/Horsepower Ratio is part of the Fuel consumption calculation. Wich makes sense, as a heavier loaded engine needs to (literally) pull more weight.
- However to my knowledge. Max Speed is only used for the dogfighting Score. It seems likely that Economic Speed is used for the fuel consumption to figure out the range.

*In the Real world, the wind decides in wich direction Landing strips are build and in which direciton the carrier moves. Basically it should substract from the takeoff speed.

[zgrssd]

Time to sample some data about starting fighter aircraft Speed values on different planets, to see if I can find any patterns:
Planet 1: 0.33g, 10m/s, 446mBa
Critical Speed: 784
Max Speed: 289
Takeoff: 122
Eco: 229
Crit Ground: 1452
Max Ground: 265
Range: 4462

Planet 2: 0.56g, 13m/s, 625 mBar
Crit Speed: 713
Max Speed: 239
Takeoff: 144
Eco: 179
Crit Ground: 640
Max Ground: 207
Range: 2948

Planet 3: 0.32g, 1m/s, 284 mbar
Crit Speed: 927
Max Speed: 263
Max Speed2: 185
Takeoff: 159
Eco: 175
Crit Ground: 2225
Max Ground: 171
Range: 1760

Preliminary results:
Planet 3 has similar gravity to Planet 1, but -37% Pressure and -9m windspeed
Crit Speed: 784-927, +15% increase, about half pressure drop
Max Speed 289-263, -9% drop
Planet 3 is the first one with a 2nd, lower Max Speed. Might be due to Gravity > pressure in this case, I need more data.
Takeoff 122-159, +24% increase
Eco 229-175, -24% drop - same as takeoff speed increased
Crit Ground: 1452-2225, +35% increase - mirrors pressure decrease almsot perfectly
Max Ground: 265-171, -35% drop - again mirrors pressure drop
Range: 4462-1760, -61% drop, roughly double pressure drop

What can I see:
Both Critical Air and Critical Ground speed seem to get bigger with lower air pressure. I guess it is the Max Speed from Air-resistance.
Max Air Speed is barely affected by the pressure drop. So the Dogfighting performance should be similar (especailly if you consider the enemy also is lower) across atmosphere densities
Max Ground speed however is strong affected, but unlike max Air it only affects matching the takeoff speed - if you can not meet it, the design plain fails
Apparently there is sometimes a 2nd max speed. I need to look out for further examples to verify the purpose/pattern
Takeoff speed increased by as much as Eco Speed decreased - so both worsened the same ratio. Their distance can thus be a major measure of aircraft viability. I would bet Takeoff acts as lower bound for Eco Speed too - can not fly efficiently, if you can not keep in the air at all.
Range has me stumped. I expected it to drop proportional to Eco Speed - but instead it changed the most of all values. Given that every stated thing that affecst it stayed roughly the same, this is really odd.

[zgrssd]

I will be expanding the sampling to the Turning, Agility and Dogfighting Scores (TAD). I will also add the result of Pressure (in Full Bar) / Gravity to the planets
I still have enough savegames to do that for the 3 planets.

Planet 1: 0.33g, 10m/s, 446mBar, 1.35
Critical Speed: 784
Max Speed: 289
Takeoff: 122
Eco: 229
Crit Ground: 1452
Max Ground: 265
Range: 4462
TAD: 9/16/19

Planet 2: 0.56g, 13m/s, 625 mBar, 1.12
Crit Speed: 713
Max Speed: 239
Takeoff: 144
Eco: 179
Crit Ground: 640
Max Ground: 207
Range: 2948
TAD: 9/16/18

Planet 3: 0.32g, 1m/s, 284 mbar, 0.8875
Crit Speed: 927
Max Speed: 263
Max Speed2: 185
Takeoff: 159
Eco: 175
Crit Ground: 2225
Max Ground: 171
Range: 1760
TAD: 15/37/20

Apended preliminary results:
TAD scores are - oddly - almsot indentical between Planet 1 and 2. Meanwhile planet 3 has about twice the T and A score - but is the only one with a Dogfighting score much lower then it's Agility. The planet has noteably a bad (<1) Pressure/Gravity Ratio wich does seem to enforce a 2nd, lower Max Speed

[zgrssd]

For this sampling, I tried large Siwa worlds to get some higher Gravity counts into my sample.
Interstingly I do seem to be getting somewhat different Horsepower and Wignload values: 0.35 and 167 respectively. Apparently the game has several starting designs, some of these use a 1000 Engine Power Engine. Since I did not realize that beforehand, that means my sample data past the first 3 is faulty.
The best I can do is try to calcualte some ratios now.

Planet 4: 0.98g, 8m/s, 814 mBar, 0.8306
Crit Speed: 713
Max Speed: 247
Takeoff: 166
Eco: 187
Crit Ground: 319
Max Ground: 195
Range: 1773
TAD: 15/37/22

Planet 5: 1.02g, 6m/s, 1109 mBar, 1.0872
Crit Air: 750
Max Speed: 232
Takeoff: 143
Eco: 172
Crit Ground: 241
Max Ground: 183
Range: 2765
TAD: 9/16/18

Planet 6: 0.86g, 5m/s, 989 mBar, 1.15
Crit Air: 713
Max Speed: 245
Takeoff: 137
Eco: 185
Crit Ground: 299
Max Ground: 199
Range: 3126
TAD: 9/16/18

Planet 7: 1.13g, 6m/s, 972 mBar, 0.8602
Crit Air: 713
Max Speed: 256
Takeoff: 163
Eco: 196
Crit Ground: 250
Max Ground: 196
Range: 1917
TAD: 15/37/23

More calcualtions:
Time to look at Max Speed/Eco Speed/Takeoff/Gravity ratio. According to to the design log, Eco Speed is based on the other 3. Particulary I wonder what the average between Max and Takeoff Speed is and how far eco-speed is from it. I am given A and B value for Planet 3, using either max speed
Planet 1: 289/229/122/0.33g, average: 205.5, difference: +23,5
Planet 2: 239/179/144/0.56g, average: 191.5, difference: -12.5
Planet 3a: 263/175/159/0.32g, average: 211, difference: -36
Planet 3b: 185/175/159/0.32g, average: 172, difference: +3
Planet 4: 247/187/166/0.98g, average: 206.5, difference: -19.5
Planet 5: 232/172/143/1.02g, average: 187.5, difference: -15.5
Planet 6: 245/185/137/0.86g, average: 191.0, difference: -6
Planet 7: 256/196/163/1.13g, average: 209.5, difference: -13.5

Excluding Planet 3 - wich has outliers either direction - the Eco speed seems to be the average (Max, Takeoff) +/- 20. Still not a solid basis, however.

[shabowie]

LOL, love this game, so compliscated. When somebody really cracks the hood I'm amazed twice, once at the elegance of the way certain systems work, and then that it works at all.

The developer is a stud.

[&o]