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By trial, error, and advice from others, I have learned alot about building competitive BDArmory Fighter aircraft. Because of the growing number of people interested in making competitive aircraft, but do not have the knowledge how, I am making this guide on how to make competitive BDArmory Fighter aircraft. Feel free to suggest additions, and to share your advice. This guide will be divided into two parts: physical design tips, and AI tuning/weapons selection tips. According to @Box of Stardust, an experienced designer on the forums, making a good fighter plane is "25% airframe, 30% weapons and utilization, and 45% AI tuning." Also, keep in mind these characteristics, suggested by @Box of Stardust. These characteristics are the main traits that define an airplanes strengths, weaknesses, and performance. Maneuverability: Maneuverability of an aircraft. Aside from general control authority, it also includes the ability to perform extreme dogfighting maneuvers, which may be influenced by factors such as thrust. Propulsion: Acceleration and speed of an aircraft. High thrust-to-weight is good, but can also be influenced by aerodynamics; know the ins-and-outs of the KSP aerodynamics system to help create less draggy aircraft. Endurance: Time an aircraft can remain in combat before running out of fuel. 15 minutes dry thrust according to KER readout is the lower bound I recommend. Size: Size and form factor of an aircraft. Influences ability to avoid damage, due to being a harder-to-hit target, as well as smaller radar cross section. Damage Mitigation: Ability to take damage and remain combat effective. To clarify: not simply surviving damage, but remaining able to fly effectively despite the damage and not be locked into basic defensive actions only, and if possible, continue fighting. Structural durability comes into play greatly. Offensive Capabilities: Aircraft armament and the effectiveness of the utilization of the weapons (weapon ranges and such). Flight Control: Ability of the AI tuning to both push an aircraft to its maneuvering limits and maintain stability and directional control. The AI must be able to perform extreme dogfighting maneuvers, evade incoming fire, pursue enemy aircraft, and be accurate when firing on a target. Additionally, the ability for the AI to accomplish this despite the aircraft having taken damage. (Note: this has become increasingly harder to judge with BDA 1.2.) Now, we will start with the structural/aerodynamic construction: 1. Never use manned aircraft, unless required by competition rules. And if possible, use lawn ch- err, command seats. Command modules weigh almost a ton, and increase the size(and thus, radar cross section (RCS), and more area for the enemy guns to aim for). Additionally, avoid Mk1 (1.25m) parts. They again add unnecessary size. 2. Aim for about 300 units of liquid fuel. Again, you should get your fuel from sources other than 1.25m parts. The Big-S wing strake can hold 100 units each and, combined with 2 Mk0 liquid fuel tanks, provides you with enough liquid fuel to provide sufficient endurance. 3. Do not use the stock panther engine. Use the AirplanePlus tiger 0.625m engine. It offers greater thrust for the weight, and generates much more electric charge than the Panthers for its thrust. Additionally, the tiger runs at a "cool" temperature for the thrust, allowing the shortest AIM-9 lock range of any afterburner(AB)capable engine, approximately 2.8 km in non AB mode, with a low throttle setting, compared to just over 3km for the panther. Although 0.2 km might not sound that much of a difference, it is, when you take into account the near-mach 2 closing speeds. Just that little distance may allow you to fire your AIM-9s and cause the enemy to dodge before firing theirs. 4. Design your airplane for maximum battle durability. Avoid attaching multiple wings to each other, instead, attach all wings to a hidden structural part, like a structural I beam inside Big-S wing strakes. Ideally, any one part exploding shouldn't have any affect on the others. However, this normally isn't possible. And since BDA 1.1/2, hidden parts wont receive damage until the part covering it explodes, (unless you got an armor penetrating shell). So, you attach all wings to this hidden part, to ensure maximum battle durability. Additionally, place wings close to the fuselage(e.g, small wingspan), and if competition rules allow, clip wings close to the center. This insures that most lift is coming from the center of the airplane. Thus, the plane wont spiral out of control when a wing is lost. (FYI, lift from the body/fuselage IRL is called "body lift". This is what allowed that Israeli F-15 to land on 1 wing. The F-15s body generates a good amount of lift) Now we will discuss aerodynamics, and making the best plane aerodynamically. 1. More wings almost never hurts. Turn rate is 85% determined by wing loading (which is the amount of lift each square unit of wing has to produce in order for lift to equal the weight of the aircraft). More wing area means less lift each square needs to produce to equal the aircrafts weight. Thus, the lower the wing loading, the more excess lift is available. More excess lift means that you can turn with less Angle of Attack (AoA), meaning less drag. Less drag means less thrust is needed, which also means less fuel can be carried. That means less weight. And weight is probably any aircraft designers worst enemy. Alternatively, the reduction in drag can also be utilized to improve energy retention, the greatest advantage in a dogfight. Overall, high lift is key to a high maneuverability aircraft, and gives you a significant edge over opponents without this knowledge. The question is, how much wing is ideal for an aircraft? After all, wings do weigh, and too many wings induces unnecessary drag. From my designs, I have found that around 1.2 to 1.4 units of wing area per ton is ideal. Anything under 0.9 is insufficient lift, and over 1.7 produces excessive drag. And, like stated in the structural section, moving wings inwards, and clipping wings near the middle are ideal, because if the lift is coming very close from the lateral center, the loss of a wing will not severely affect flight performance. TL; DR: you should aim for about 1.2-1.4 units of wing area per ton of aircraft to maximize excess lift, and to minimize excessive drag. 2. If maneuverability is 85% wing loading, whats the remaining 15%? Thrust to Weight radio (TWR). Why does TWR have anything to do with maneuverability? Because even the most perfectly designed wing produces drag while turning. And slowing down reduces your turn rate. Thus, to keep up energy, you need thrust. Practically, your craft will weigh about 6.5-8.5t loaded, depending on the amount of guns, ammo, fuel, missiles, etc. Anything above 8.5t is generally a bit to heavy for ideal performance. And its very hard to make a well-designed aircraft under 6.5t. If the craft weights over 7.5t, use 7-8 Tiger engines. If under 7.5t, use about 5-6 tiger engines. Optimal numbers may vary depending on other factors (mainly drag and wing loading). 3. Place elevators as far back as possible. This maximizes pitch authority, which (as we will see later) allows you to decrease control deflection, which is key to providing ideal response time. Also, 4-6 reaction wheels are ideal. 4. Place the center of lift(CoL)just behing the center of gravity(CoG). Ideally, the center of the CoL sphere should be halfway between the center and outer edge of the CoG sphere, or maybe maybe a tad bit closer to the CoG, depending on your plane design. 5. This tip (first suggested by @goduranus) is a poorly known (and counter-intuitive) one, but can greatly increase responsiveness. This is the theory behind this tip: all control surfaces on an aircraft should be able to respond to an full input in 0.3 seconds. In other words, the control surface should have no more than 0.3 second "lag time" from center to max allowable deflection. Unfortunately, most control surfaces default deflection values provide lag time in excess of 0.5 seconds, some approaching 1 second. To counter this, you reduce the max deflection untill an 0.3 second lag time is achieved. To calculate the exact number for the max deflection, you multiply the control surfaces actuator speed in degrees per second (found by right-clicking the part) by 0.3. Then, divide this by the maximum deflection in degrees (found next to the actuator speed). Multiply the result by 100, and that number shoud be your max deflection. Very few surfaces (namely, the advanced canard) can be left at 100 and still meet the 0.3 sec limit, and none can be increased to 150. This is why you want your elevators as far back as possible(to maximize control authority) and a CoL just behind the CoG(to minimize resistance to pitch up). 6. Choose the right control surfaces! In order to get maximum deflection, but still remain in the 0.3 sec timeframe, you want the maximum actuator speed. Note that this tip isn't very critical, especially if your plane is well designed. Also, having a bigger control surface with slightly slower actuator speed is better than a smaller surface with a faster speed. This is why the best control surface IMHO is the Big-S type 1. It combines ideal size with sufficient speed. And the best canard IMHO is (not surprisingly) the advanced canard. When more size is needed, use the standard canard. This concludes the aircraft design section. The next part of this guide covers proper selection and tuning of BDArmory weapons, countermeasures, and sensors. It also covers tuning the weapons manager settings. 1. Don't use radar. Its simply dead weight right now. The most competitive drones have such a low Radar Cross Section (RCS), that trying to lock on them is virtually impossible, especially when they have jammers. Besides, they can dodge AMRAAM's easily anyway. So just don't use radar. Unless you're in a competition that requires one. 2. Spam sidewinders! Since the BDA 1.1 update, planes have gotten much more damage-resistant. Meaning a single sidewinder wont do much to a well-designed aircraft. Actually, many planes can take multiple missile hits and fight as if nothing happened. So you need a lot of sidewinders. Ideally between 8 and 12. And you want the weapons manager to fire 2 at a time, but we will discuss that later. 2. Don't gun spam. Prior to BDA 1.1, when heat was used to determine damage, planes were not very damage-tolerant. That's when the idea of gun spamming in the merge was invented with @Eidahlil's Cookie. A "flying ceiling fan" with 8 GAU-8 cannons. It basically hovered while rotating to aim at you. Unfortunately, this didn't work well, due to the fact that it can't dogfight. Soon afterwards, I was trying to make an ultimate dogfighter, but ended up with one of the most hated planes in the ASC competition. The Du-3. Basically, it was a guns-only airplane with 5 vulcans, a low top speed(to reduce IR signature), and very manuverable. Unknowingly, the decision to make it guns only is what gave it its formidable reputation. Here is why: because it came in slowly(~210 m/s), the engine was on very low throttle. Thus an IR lock would be achieved at just under 3km. Now, when the AI has a missile lock, it doesn't fire immediately, which is simply how the AI works. Then, people left their guns range at 2.5km (a big no-no today). Before the AI could fire its sidewinder, it reached gun range. And there is about a 0.5-1 second lag when switching weapons. The Du-3 never had to switch between weapons, meaning it sent a hailstorm of 20mm bullets downrange immediately at 2.5 km. The other airplanes, because of the lag, didn't start firing until ~2km or less. Thats over a half kilometer. Often, before they could evem return fire, the Du-3s would already have destroyed one of the enemies. Thus, when fighting a Du-3, you were basically guaranteed to loose a plane or two (sometimes all 3) in the head on pass. Numerous other aircraft (@dundun93's TFD 2.1 with 16 Vulcans, @Box of Stardust's Basillisk with 6 Vulcans and Flying Gunbrick with 10) followed this tactic, with great success, until the BDA 1.1 update. And thats when gun spam because impractical. Because of planes increased damage tolerance, it is rare to get enemies in the merge. And guns/ammo are heavy. Thus, carrying around all those guns and reduced maneuverability. Now, this has always been true, but previously, you could turn a 3v3 into a 3v1 just with the merge. Now, you need to dogfight to get enemies. And gun spammers are normally less-than-ideal dogfighters. Additionally, some new methods eliminate the merge all together, namely the Pre-Routing device(PRD), and certain weapons manager tweaks. We will discuss both soon. TL;DR. Gun spamming used to be a viable tactic, but isn't anymore. You want no less than 3, but no more than 6 Vulcans. And 4 ammo boxes is perfect. Also, pressing F2 in the SPH will show you how your guns are aimed, e.g, converging, diverging, how far away they converge. 3. Set your Vulcans max engagament range to under 1.3km. Also, set the gun range on the weapons manager (by right-clicking it) to just over the number you choose for your Vulcans. This is why: in the ASC challenge, it was noticed that planes were not using their sidewinders. This is because of the 2.5km gun range. And after the merge, airplanes are pretty close together. Normally closer than 2.5km. Thus, when enemy planes were extending to ~2 km and turning around, a perfect AIM-9 shot, the planes were wasting ammo on hopeless long-range vulcan shots, instead of properly used the AIM-9s. Thus, @box of stardust started the trend of reducing gun range to force planes to utilize their AIM-9s. Although reducing Vulcan range seems counter-intuitive, you have to think like this: at 2 km, which is more effective: Vulcan fire, or AIM-9s? At 1.5km? 1.25km? Generally, over 1.3km, AIM-9s are more effective than cannon, especially if fired two at a time. Under 1km, Vulcan fire is the most effective. The exact number between these two varies. For example, if your plane has a limited number of AIM-9s, or your plane can exceptionally aim long range gunfire, you might want a value on the high end, maybe 1.25km. Alternatively, if your plane runs out of ammo quickly, you would want a lower value. Maybe 1km. I personally choose about 1.0-1.1 km. Note: I know I didn't quite to the best job explaining this, so maybe someone could come up with a simpler explanation? 4. Fire two at a time! In the weapons manager, by right-clicking on the part, set the missiles per target to 2. That way, it fires two AIM-9s at a time. 1 AIM-9 at a time is not enough to do any significant damage in the latest BDA(also, it means you only have to dodge half as many missiles), and 3 depletes your missiles too quickly. 5. Set your intervals properly. In the weapons manager settings, put the "firing interval" at 1, and the "burst length" at 0. You want the plane to fire guns in short intervals, with short breaks inbetween, not continually. This ensures that less ammo is wasted, while keeping effectiveness. In my testing, non-continuous fire is just as effective as continuous fire. 6. In order to avoid your missiles colliding with you at seperation, shorten the, missile rails as much as possible. Additionally, you want forward jettisoning missiles. By default, its on lateral, or downwards ejection. Right-click on the AIM-9, and set the drop time to zero, decouple speed to 10, and forward firing, not lateral. Also, set the max engagement range to about 4-4.5 km. This is to avoid the missile exploding immediately after launch due to the loss of a long-range lock. 7. Use a PRD! A PRD, Pre-Routing device, works by firing a missile without a lock. This missile will trigger the enemies RWR, and cause them to dodge, but the missile doesn't have a lock. Meaning you can avoid merges by firing a PRD just prior to the merge. The only stock missile that will work is the RBS-15 cruise missile. Set its max engagement range to about 4-7km (experiment to see what works best). Also, set it to engage air targets only. It will fire the missile at the set range, and the enemies will respond as if it was a guided missile. There are more complicated PRD's, that fire unguided sidewinders/AMRAAMs, using some modular missile guide programming. But the RBS-15 PRD should be just fine. Additionally, the more complicated PRD's require decouplers(which are banned in some challenges), unlike the RBS-15 one, which doesn't need any decouplers. Just the missile rail. I reccomended you place the PRD on the belly of the airplane. Not on the top. 8. Always have at least 4 flare boxes, and at least 2 chaff boxes. Use ECM only if necessary. Normally, a PRD will stop AMRAAM shots by causing the enemies to dodge before they can fire their AMRAAMS at you. This is because most competitive drones have very small frontal RCS, meaning AMRAAMs lock at about 3-4 km. A little after your PRD should fire. If you use jammers, set them to activate with the gear action group. Don't use toggle, use activate. And, angle 2 of your your flare boxes at 45° angle backwards. And all of the flare boxes should have an eject speed of 30. Lastly, we will cover tuning the AI, probably the most important part of designing any BDArmory aircraft. 1. Leave the Pitck Ki on 5, and Max G/Max AoA on the maximum allowable values. Default and minimum altitudes: the default altitude can be kept as it, though setting it a bit higher can be advantageous in a dogfight. The minimum altitude should be put at 300 for a plane designed by these tips. Then, if you notice the plane crashing into the ground abnormally, raise it to 400. Steer Factor: steer factor is a multiplier that determines how much control input is used to turn the airplane. Higher values mean larger inputs for a given turn. (Here is a simplified example(not using the actual values): with steer factor at, say, 5, it will turn with 50% input for a target 30° above it. Put it at 10, and it uses full input). In order to properly set it, I highly reccomended you fly the finished plane by hand. That way, you have a general sense of what the capabilities of the airplane are. If you notice that the plane isn't turning fast enough, increase the steer factor. Alternatively, if the plane is turning too sharply, and bleeding airspeed unnecessarily, reduce the steer factor. Steer damping: the easiest way to adjust steer damping is this: place a stationary target with a weapons manager on the grass by the runway. Next, launch your craft. Temporarily set its guns to engage ground targets. Now, put the airplane and stationary target on different teams, and battle! While the plane is firing at the target, look to see how steady it is flying. If it is oscillating/wobbling in pitch/roll/yaw, increase the damping. If it appears to be steady, decrease the steer damping as much as possible while still being steady. You want the lowest steer damping value that provides stability, as excessive damping negatively affects turn performance. Min Combat speed should be set to around 40. So should the takeoff speed. Idle speed can be left as is, although increasing it to 200 never hurts. Max speed can be left as is, or maybe lowered to about 300. But never increase it. You dont want your plane merging with full afterburner, do you? BTW, here is a design that utilizes the tactics suggested in this guide, except the PRD, which didn't seem to help this design. the updated version has a MLRS. https://kerbalx.com/dundun92/Du-11 Updated version: https://kerbalx.com/dundun92/Du-11B-Blk-10