KerbalX

Details

• Type: SPH
• Class: spaceplane
• Part Count: 51
• Pure Stock
• KSP: 1.11.0

Mods

• Making History DLC
• Squad (stock)

The KT-100A Griffon is the first in a series of smaller-sized space planes (the 100 series) meant for training purposes. I also highly recommend the use of Atmospheric Autopilot which will make aircraft operation much easier although flying with just stock SAS is certainly possible.

The Griffon, unlike some of my other space planes, is extremely easy to fly and relies on a single RAPIER engine which operates both as a jet and rocket engine allowing for a relatively small spacecraft design compared to the use of two types of engines.

The single RAPIER engine in air breathing mode is optimal for high atmospheric speeds in excess of 1,000 m/s and altitudes in excess of 17 km. It still operates reasonably well at lower altitudes so it’s perfectly capable as an airplane. It provides about 180 kN of thrust in closed cycle mode which is almost excessive for the size of the spacecraft but means that ascents will be relatively quick for it as a space plane.

Takeoff and Initial Ascent

The takeoff is relatively simple for all missions and if you deploy both sets of flaps you should automatically ascend without further pilot intervention at a speed of approximately 120 m/s. The sharp ascent should be moderated by retracting both sets of flaps and landing gear and should be a fairly stable climb.

The RAPIER provides considerable, almost excessive, thrust so you can set a fairly high rate of climb keeping in mind that it should be at least 750 m/s by the time you reach 10 km and that too shallow of a climb may result in excessive speeds that could stress the plane. If your mission includes reaching space or reaching a stable orbit you’ll probably switch modes somewhere between 17 and 20 km or about the time that your acceleration starts to drop sharply with the thinning atmosphere.

If you plan on staying within the atmosphere you should keep your high altitude cruise between 17 and 19 km which will allow you for speeds in excess of 2,000 m/s although it might excessive heating and stresses on the aircraft which should be monitored.

Ascent to Space and Orbit

You’ll probably want to switch to closed cycle mode between 17 km and 20 km especially as your acceleration starts to drop sharply. The ascent to space is comparatively simple with the RAPIER engine which gives you plenty of leeway to decide the best estimated apoapsis before shutting down your engine and drifting to space. I usually recommend about 85 km as you will initially rapidly lose acceleration and it may be barely 70 - 75 km by the time you actually reach space.

If you plan on further orbital operations I recommend simply reaching a stable orbit first, even one with high eccentricity, before making additional burns to achieve your desired orbit as stock settings don’t cause an orbit to decay further. You’ll probably have as low as 500 dV to as high as 650 dV left by the time you reach orbit.

Orbital Operations

This space plane is basically just a no-frills trainer meant for practicing all the skills associated with the use of the RAPIER engine so your options for other missions will be rather limited. You should have at least 500 dV to divide between operations and your final re-entry burn which allows for considerable orbital changes as well as practicing rendezvous with other objects in orbit.

I have included considerable electrical capacity along with a pair of small solar panels so you shouldn’t get stranded in LKO (Low Kerbin Orbit) and under stock settings can decide when you’re going to re-enter the atmosphere and make your landing. There are also a pair of RCS thrusters and some monopropellent fuel for attitude adjustment so close rendezvous operations are certainly possible.

Re-entry and Landing

You shouldn’t need much fuel for your re-entry burn with one of the benefits of this space plane being that you’ll still have plenty of fuel when you switch back to air-breathing mode so it shouldn’t be too difficult to guide yourself to most of the bases on Kerbal.

If you plan on landing at KSC then I recommend a glide slope of about 3 degrees, deploying both sets of flaps on approach and touching down around 60 to 80 m/s. You should do a bit of a flare up as you touch down so the rear gear wheels touch first although the low clearance of the aircraft’s tail might sometimes make this difficult.

Built in the SPH in KSP version 1.11.0.