KerbalX

1.12.5 Craft File

• Kerbin Warbird Preservation Society
• Trades off a bit of speed for extra range and foldy wings
• Top speed seems to have improved a bit by 2 to 217 m/s (1.10.1)
• Flight Tested and 1.12.5 Approved!

• Type: SPH
• Class: ship
• Part Count: 58
• Pure Stock
• KSP: 1.12.5

Multi-Atmosphere Certified

There are two unique features of this craft that allow it to fly as-is on other planets with reasonably dense atmospheres:

Foldy-Wings

Since the wings can be folded and re-deployed it can be shipped to other planets more easily than other fixed-wing designs. When folded and gear retracted, the dimensions are: H:4.6, W:4.2, L:9.4. The hinge in the wings continues to be a source of extra drag/weight (1.10.1) so a bit of top speed is traded for the wing folding ability but not much of a hit.

Control Surface Manual Trim Adjustment

Although currently trimmed for straight & level flight in Kerbin atmosphere, you can use the U/D and L/R translation keys in-flight to make trim adjustments for any atmosphere/altitude.

Description

The Crusader is a hearty and reliable flyer known for its amazing ability to leap off the deck and land on a dime thanks to its powerful Duplex-Twister radial engine.

A stock aircraft called F5U Crusader. Built with 58 of the finest parts, its root part is Mark2Cockpit.

Built in the SPH in KSP version 1.12.5.

Design Notes

My warbirds are a bit more complex in design than they appear; particularly as it relates to the throttle-linked engine and flight systems.

First and foremost, the idea of Hands-On flight control is paramount. I can’t stand the idea of having to manage pitch control and other various flight surfaces by opening up some window. Consistent with all of my craft, you fly this one with the throttle and joystick (or keypad) alone. A single KAL-1000 is pre-tuned to manage the mundane for you.

For best results, follow the blueprint flight ops recommendation for throttle position at the various stages of flight. I purposefully tied this to the 1/3, 2/3, and Full Power positions on your throttle. Basically you are beginning a takeoff or landing in the 1/3 throttle position and adjusting power up/down as needed. At each interval, you should allow the warbird to reach its max speed before gradually increasing throttle. You can downshift as fast as you want… that huge propeller is the most effective airbrake in the game! Increasing power should be gradual between 1/3, 2/3, and full power. Just watch your speed and throttle-up accordingly.

Notable in my warbird designs are the engine systems I created to deal with the excessive unwanted roll that would otherwise be present in a single-engine propeller craft. I hide counter-rotating ducted fans in the cowl that help to counter a lot of the torque induced roll. Not to mention the added power boost really makes these a joy to fly. To justify the use of space, I emptied out all the fuel from the cowl and air intake locations.

Since we are dealing with a combination of standard propeller and ducted fans, the torque-roll offset is not perfect. To counter the remaining differential I set the ailerons to their deployed state and add some trim adjustment with the single KAL-1000. Since the differential would change based on altitude and atmospheric density, I went with a low altitude profile for the aileron adjustment. Same is true for elevators… You do need to include some baseline trim settings to keep it flying level at speed.

In my flight testing with the warbirds (Bronco and Crusader) I find that I only need my baseline trim adjustments to put me on straight and level flight under two scenarios. Immediately following takeoff and max speed at sea level. Connecting those two points in the KAL-1000 with a straight line seems to be adequate for all flying conditions in between. So if you look at how I setup the KAL, that’s basically all I’m doing for every one of the settings. The two data points are takeoff and max power connected with a straight line.

A key point, is understanding that both ailerons and elevators can be set to their Deployed state and will still accept control inputs! This is an extremely useful, but seldom exploited feature. This allows you to add in additional baseline trim for various throttle positions. I also wanted to maintain some manual trim adjustment ability with the U/D, L/R translation keys. Since we can’t assign trim to both the KAL and translation keys at the same time (well, you can, but the KAL assignment renders the translation key assignments useless) I left the rear-most elevon of the empennage unassigned on the KAL.

As a default, the rear elevon is Deployed but set to a baseline value of zero and the deploy angle is tied to the translation keys. Keep in mind, although it is set to deployed, it still has pitch control flowing through! With this setup, if you decide to fly at higher altitudes, you can use the translate keys for roll and elevator trim control and the KAL can still feed its baseline adjustments to the other control surfaces. If I do tinker with manual trim during flight, I also know that all I need to do to undo the adjustments is set the rear-most elevon back to zero. This seems to work very well for me, and since I like to fly the warbirds below 500m anyway… I don’t really even need to touch the manual trim; but it’s there if I ever need it.

These things fly like no other craft in the game. With flaps deployed, they pull their tails up into the air to let you know when they are ready to fly at very low speeds (about 35 m/s). You can land them on a postage stamp by cutting throttle to zero when you are ready to STOP. It took me a little getting use to. …but once I figured out I could land these things as if they were being restrained by tailhook on an aircraft carrier, I started landing and taking off from some very interesting locations.

You might also notice that I do add a little bit of negative pitch to the big prop at the zero throttle position. This is by design and will let you hold brakes (very carefully!) and apply a little bit of throttle to spin up the prop and then drift backwards to get yourself out of jams if you drive into something while taxing on the ground. You do want to avoid holding down the brake and spinning up the engine, it has so much power and the craft is so light it will nose over. To recover from this position (if no damage) just retract/extend the landing gear.