[1.4.x] The RAT Pack - Ram Air Turbines, Terrain Warning, Thrust Reversers

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Forum user @satnet created this nice little mod to give your planes EC even when the engines are off.  Based on real-life parts.  Original thread is here:


After noticing a sharp rise in crashes Gene Kerman commissioned a study on why rockets and planes crash. The resulting 3,151 page report was turned over to SatNet Aerospace to research and develop parts that could reduce crashes or make them more survivable. The first parts to come out of the project were Ram Air Turbines and the group was quickly dubbed “The RAT Pack". Even as they expanded into more flight safety parts the name stuck.



Terrain Awareness and Warning System.  It is as close as it looks and the plane did survive (barely).




LEST Saving The Day.  Launch Escape System Trigger aborting automatically.




Terrain Radar.  Landing on the Mun.




A RAT-360 and RAT-6000 on a plane landing on Duna. The RAT-360 is center of the frame and the RAT-6000 is in the lower right.




Active TR-L.  An activated thrust reverser with an LV-N.




Inactive TR-L.  An inactive thrust reverser with an LV-N.




A TR-1 with a RAPIER installed.




RAT-6000 Animation:




The RAT Pack:

Ram Air Turbines

The RAT Pack provides Ram Air Turbines that generate power from flowing air. I was partly inspired by a documentary on the "Gimli Glider", a 767 that had to glide to a landing with nothing but batteries and a RAT to power critical systems. A couple of spaceplane landings where I had to constantly manage electric charge to maintain control and keep enough for the landing gave me some incentive to actually build it. The RATs are designed to provide emergency power and have peak power at or slightly above that of an RTG. Electric charge output is a function of both airspeed and atmospheric density.


  • RAT-1 "Pinwheel" Ram Air Turbine - As basic as they come, it provides little power and must be activated manually.
  • RAT-360 "Cage Master" Ram Air Turbine - Generates more power and will automatically start up when electric charge is depleted.
  • RAT-720 "Topper" Ram Air Turbine - A RAT built into a nosecone. It has a higher peak power than the RAT-360, but has a performance curve similar to the RAT-1.
  • RAT-6000 "Pack Master" Ram Air Turbine - The most powerful RAT. This one has the ability to control electric charge flowing from its internal battery and turns it on only when it is activating. It is able to generate peak power over a broader range.
  • EPM-MK3 "Emu" Emergency Power Unit - A complete emergency power solution with a RAT, Fuel Cell, and APU.


Thrust Reversers

Thrust Reversers redirect the engine thrust. They are used to reduce stopping distance once landed. I developed it primarily for Duna spaceplanes where a short stopping distance is a huge asset. They will redirect the thrust of the engine attached to them. Attaching multiple engines will not give you the desired behavior as only one engine will be reversed.

  • TR-1 “Backup" Thrust Reverser - Designed to fit a Turbojet or RAPIER engine.
  • TR-L “Way Back" Thrust Reverser - Designed to fit longer 1.5 m engines, particularly the LV-N.


 Terrain Awareness and Warning Systems

A Terrain Awareness and Warning Systems (TAWS) gives you a chance to avoid a crash by warning you while you still have some time to react. It uses the radar altimeter and some calculations to figure out what the terrain looks like. It also has an obstacle detecting radar (FLT Radar), however it only activates below a certain altitude and uses a fair amount of power when in use.

  • TAWS-1 "Lookout" Warning System - Equipped with Ground Proximity Warning System (GPWS) and Forward Looking Terrain (FLT) Radar.
  • TRS-1 "Lookdown" Terrain Radar - Terrain scanning to improve landings.

Launch Escape System Trigger

I came across this post Launch Escape System Rocket Stack Failure Detection and thought it was in line with this mod and a great idea.

  • LEST-1 "Oops" LES Trigger - Detects a unplanned dis-assembly and hits the abort button for you.



 Questions and Answers:


Q: Are these RATs realistic?

A:Somewhat. The power curves where inspired by real RATs, but have been heavily Kerbalized.

Q: Why doesn't my speed on the power curve match my vessel speed?

A: The RAT uses an effective speed calculation that takes into account orientation, parts blocking airflow, and pressure. It will only match up with vessel speed at sea level, going straight, and without anything in front of the part.

Q: Where can I use RATs?

A: Anywhere with an atmosphere. Kerbin, Duna, Eve, Laythe are all good places to use them. Jool and Kerbol might work, but you'll probably be crushed or melted before you get any power.

Q: What happens if I run out of power landing on the Mun with a RAT?

A: You will probably hit the Mun and the RAT will be destroyed.

Q: What happens if I run out of power landing at the KSC with a RAT?

A: If you have an auto-activating RAT it will deploy and start generating power. If it is a manual RAT, you can't activate it after losing power, so prepare for high speed litho-braking.

Q: Do RATs work inside fairings or cargo bays?

A: No, they need to be in the air-stream.

Q: How does orientation affect RATs?

A: Yes, they produce the most power when pointed in the prograde direction.

Q: Can I fly backwards using a thrust reverser?

A: Yes, though it is not recommended. Most planes and rockets are not aerodynamically stable in both directions.

Q: How much thrust will a thrust reverser reverse?

A: Short answer:  you lose a lot of thrust, but it should be enough to stop quickly.
A: Long Answer:  Each TR has a thrust modifier which defaults to 50% intended to account for thrust lost to exhaust escaping to the sides. Additionally the thrust direction is not directed in reverse, but in a 45 degree angle above and below the engine. The net thrust is in reverse, but there are significant losses from the thrust directed up and down that cancels out.

Q: Will a thrust reverser work in space?

A: It will, though you are effectively reducing your engine efficiency, so you are better off re-orienting.

Q: Why doesn't my descent rate match my vertical speed?

A: They are similar but different values. Descent rate is probably better described as ground closure rate. It is how quickly you are approaching the ground. Vertical speed is how quickly you are changing altitude relative to a common reference radius (i.e. sea-level). If you are on level terrain they will be the same. If however the ground is rising relative to sea-level you will have a higher ground closure rate than vertical speed which is a really important distinction when deciding whether you will hit the ground at some point in the near future.

Q: Will I always have time to pull up when TAWS issues a warning?

A: Not necessarily. The current values are very... "Kerbal", they give you a chance at survival, but no guarantees. If you aren't trying to hit terrain it is usually enough warning to avoid the occasional near miss, but if you deliberately try to test the limits you will hit the ground at least some of the time. You can set your own values, but I found anything that would ensure survival was too conservative for the way I fly in game.


NOTE: I'm referencing the stock textures. If you modify or remove textures from the stock parts these parts will fall back to the solid black placeholder texture.

Edited by linuxgurugamer
  • Like 5

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YES! I have ALWAYS wanted turbines, because, well, why wouldn't my planes have turbines? I always needed an RTG or something... But now we don't need to carry nuclear material on every single vessel! AHAHAHAHA!  :D

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Another day, another immediately essential mod taken over by the Flying Penguins. Excellent stuff, thanks for keeping this one alive.

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Just when I decided I was going to stop building planes for a while and go visit other planets...

Beautiful mod, can't wait to use it!

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8 hours ago, Beetlecat said:


btw, @linuxgurugamer, the Spacedock "forum" link doesn't point back to here properly. Ty!

Now fixed, thanks

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