CA Mk3 Shuttle - STS-1X
by gc1ceo
uploaded 2017-09-04
(updated 2017-09-05)
49 downloads /
3
points
VAB
mod ship
#shuttle #spaceshuttle

Details

  • Type: VAB
  • Class: ship
  • Part Count: 52
  • Mods: 5

Mods

  • Cormorant Aeronology
  • Shuttle Lifting Body
  • Squad (stock)
  • TweakScale - Rescale Everything!
  • TweakableEverything

History and Background

There were plans for a reusable space planes for as long as the beginning of the dreams of spaceflight. The Space Race between the United States and Soviet Union technically began with the roughest definitions of space planes such as the X-15 which was launched via another aircraft. There were numerous plans for space planes launched from a rocket including the USAF’s Dyna-Soar (cancelled in the early 1960s) and the Soviet MIG-105. However this dream wasn’t realized until the beginning of the Nixon-era program in 1969 that eventually led to development of what became the Space Shuttle. The first orbiter, Enterprise, was finished in 1976 and went through several years of atmospheric tests with first space-capable orbiter, Columbia, finished several years later.

The launch of the Columbia on STS-1 in April 1981 began the lengthy and second-most expensive space program in history which lasted until the final mission of Space Shuttle Atlantis in July 2011. There were 135 space shuttle missions over a 30-year career with two tragic failures which saw the loss of the Challenger on January 28th, 1986 and the loss of Columbia on January 16th, 2003. Both tragedies saw the loss of the entire crews, a total of 14 astronauts. The first couple of missions with Columbia had only two crew with the external fuel tank painted white instead of the orange that became one of its designating features.

Basic Description

The CA Mk3 Shuttle STS-1X uses primarily Cormorant Aeronology parts and is modified from the original craft made by its author, Pak. It was further adjusted using advice from drtedastro on modifying gimbals, setting up Mechjeb, and making it far easier to fly. I further adjusted it to approximate the earliest configuration of the Columbia during its first two missions including a white external tank. It is designed for short LKO (Low Kerbin Orbits) carrying up to four kerbonauts and minimal payload. The primary mission profile is to use it for training on how to fly the shuttle but it is rated for a payload of up to 10 tonnes and has enough power generated by the fuel cells to stay in orbit for a while.

I recommend that many of the shuttle operations are handled through Mechjeb as the shuttle was highly automated during much of its mission length including launching, ascending, orbiting, and landing. I have included a special text container for the recommended Mechjeb settings but feel free to make adjustments as needed. I highly recommend a planned orbit between 100 and 130km with drtredastro finding 125-128 km to be the most ideal. The shuttle’s orbital maneuvering engines (OME) are monopropellent with a decent thrust of 100kN but aren’t meant to be used outside of LKO. You should have somewhere between 300 and 500 dV by the time you hit a stable orbit depending on your ascent procedure. I recommend keeping 100-130 of that in reserve for your de-orbiting process. There is a single fuel tank on board which could be utilized for emergency de-orbiting or could be used as a backup fuel source for the on-board fuel cells.

Launch, Ascent, and Orbital Procedures

The launch and ascent procedure is fairly complex compared to most of my builds, of course this was especially true for the actual Space Shuttle. You should make sure the gimbals for both the Space Shuttle Main Engines (SSME) and Orbital Maneuvering Engines (OME) are locked initially. You should also turn off force roll until a few seconds after lift-off since too quick of a forced roll may destabilize the craft.

The first step, much like in real life, is to fire the SSMEs for just a moment until the craft stabilizes. This is also the chance to initialize the first abort mode, Redundant Set Launch Sequencer (RSLS), which allows you to abort the mission simply by shutting down the SSMEs.

The second step involves firing the solid fuel boosters, releasing the launch clamps and beginning your life-off. This is the point where aborting the mission is fairly difficult and requires you to ride out the boosters before you can act further. You should keep a straight vertical ascent coupled with the roll so that the top of the shuttle is facing your desired inclination. It will wobble a bit and may look rather unstable until you have built up some velocity. It is critical that you don’t begin your gravity turn until around a velocity of 325 m/s or an altitude of 2.5km otherwise you’ll probably crash with tragic results.

The third step involves freeing the SSME gimbals, locking the SRB gimbals and starting your gravity turn at around 2.5km and 325 m/s. You will encounter some difficulty beginning the turn, if flying manually, otherwise continue it and wait for the boosters to finish their job. Once the boosters are exhausted this is the point where you can continue the ascent profile or enter into the second abort mode, Return to Launch Site (RLS), which is extremely dangerous. The RLS abort mode has you eject the boosters upon depletion and initially continue a somewhat vertical climb. The primary difficulty comes in with managing to making a roll to safely release the external tank and making a gliding return to KSC. The window for this as a viable option is extremely short and generally unnecessary in KSP unless you have a SSME failure.

The fourth step, barring a RLS abort, involves bringing the throttle back up to about 80% and keeping an eye on the Time to Apogee indicator where you want to avoid decreasing it and increasing it to at least 40-45 seconds. Once you have reached that point you know you should be able to get safely to the edge of space with little action required until that point. The shuttle will become unstable in varying degrees especially as you move into the upper atmosphere. You should avoid activating the RCS or locking the SSMEs as it usually makes it worse and unnecessarily uses up your fuel supply.

The fifth step begins when you are near to the edge of space and your apogee projection is approaching the desired altitude. You can either continue at 80% throttle or you can potentially save a bit of fuel by cutting back to 40%. Once you have reached space you can initialize an AOA (abort once around) abort with either a single complete orbit or a sub-orbital trajectory where you simply skip the circularization process. This may be necessary if a SSME failure occurs after your apogee projection has exceeded 70km and you know that you’ll hit space in any event. The rest of the AOA procedure is more or less the same as a normal landing although you may not be in a position to land at KSC.

The sixth step and circularization can be handled in a number of different ways. If you are carrying a considerable payload it is very possible that external main tank has already been depleted. This means the circularization has to be handled with the OME entirely and the external main tank can be decoupled any point before your circularization burn. If you are flying light you probably have enough fuel to use the SSMEs for the circularization burn but this turns the external fuel tank into orbital debris. A hybrid approach, in a manner similar to real life, can be use the SSMEs for most of the burn, decoupling the external tank, and switching to OMEs when your projected perigee is between 20-60km so the tank is sent to a fiery re-entry. However this approach does complicate the burn and your orbital parameters may be a bit off from your desired results. However it can result in adding 100-200 more dV available from your OMEs once you have finished your circularization. Your final orbit may not be as smooth as you want but can be easily fixed with the OMEs. The real-life space shuttle often used a second OME burn to bring their orbit to the desired parameters.

This also gives you the option for the last abort mode, ATO (Abort to Orbit), due to an insufficient burn to reach your desired orbit but enough to reach a stable orbit (anything above 69km). This may have an effect on your planned mission but it is the safest of all abort modes and was even performed on STS-93 when one of their engines under-performed during the ascent process.

Additional Description and Details

The STS-1X build is intentionally limited so your mission options aside from shuttle training and testing are a bit sparse. However the shuttle bay is very large and can be sealed to allow for safe(ish) EVA training. It has an airlock module much like the actual Space Shuttle which can independently house two crew for both easy egress and even to bring back two stranded kerbonauts. The fuel supplies should let you stay in orbit for about 30 orbits although rendezvous and docking operations can be very challenging. I have added a couple of lights to illuminate the cargo bay so it could be used night-side. There are also several fuel cells and a small fuel tank to handle recharging your electric systems. The primary fuel cells are assigned to an action key, there is also a secondary fuel cell in the rear of the cargo bay that can be activated manually. The secondary fuel cell shouldn’t be necessary under normal operations but has been included in case one of the primary cells are destroyed in a collision. The normal landing procedures require you to have enough electric charge to keep the SAS and lights active, although it is possible in theory to land in one piece without electricity.

Since this is a space place it is meant to land on the runway at the KSC although it is sturdy to make landings almost anywhere on Kerbal including emergency sea landings. The OMEs should be used to de-orbit the shuttle and afterwards should be shutoff and locked since they haven’t much of an effect in the atmosphere. The initial re-entry should be handled with a 40 degree angle of attack to allow the shuttle’s thermal underside to make the full atmospheric impact. You should keep SAS on during the entire trip and make gentle adjustments until you reach 30-40km. Once you have reached this point you should activate all your control surfaces and possibly make a series of broad S-turns to bleed off speed down to about 1000-1200 m/s so that the shuttle is controllable.

Once you hit 30-40km this is where it becomes a true space plane and can be, sometimes not so gently, glided down with control surfaces able to slow it down to around 200 m/s. It can be very difficult to land successfully at the KSC runway but the shuttle can take considerable punishment during the landing. You obviously want to extend the landing wheels probably around 1-2km and unlike real-life they can also be retracted but if you want to stay semi-realistic you should act like they can’t. When you are within 40-100m of landing you should pull back a bit to allow the rear wheels to hit the ground first, known as flaring, and gently apply brakes and the shuttle’s drogue chute. A hard landing may result in losing one of the wheels and a really hard landing may involve losing one of your wings.

Built in the VAB in KSP version 1.3.0.

MECHJEB Settings

Orbital Altitude: 128 (km)
Prevent Overheats ON
Limit Q to 35000 (pa)
Limit Acceleration to 35 (m/s)
Limit Throttle to 60-70%
Force Roll to -180 / -180
Corrective Steering Gain 2.8

Turn Start Alt 2.5 (km)
Turn Start Velocity 325 (m/s)
Turn End Alt 80 (km)
Final Flight Path Angle 0
Turn Shape 60

Efficient Thrust Profile

70% @ Lift-Off
80% @ SRB Seperation
40% @ 70km
100% @ Circularization

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