Jet RCS Demo
by jfrouleau
uploaded 2017-05-10
(updated 2017-12-26)
stock aircraft
#vtol #demo #stock

I just had an idea the other day about a way to control helicopters. I know many of you like them so I share my idea hoping that it will bring more interesting crafts. It is a sort of RCS based on jet engines. Basically objects can block the thrust of engines so by putting control surfaces we can block / unblock the thrust and it respond to pitch, yaw and roll ! Even the SAS work…ish… This craft doesn’t have any reaction wheel and those of the cockpit are disabled for demonstration purpose but its still help stability to have at least one since reaction wheels are a little more responsive that this. But the jet RCS have potentially more power helping to control heavier crafts.

I suppose this system can also be used for other vtol aircraft when more power is needed and the speed doesn’t allow normal control surface to work properly. Tips: you have more power the further you are from the CoM so at the tail of an helicopter is good and at the tips of wings.

Other applications could include boats and seaplane to turn with A and D when on water. Or quick adjustment to vertical speed on vtol aircrafts since you can activate / deactivate an engine output in a second compared to the engine time to spool up and down.

Let go your imagination ! :-)

Just by curiosity I checked how much torque the yaw junos generate on this craft to see how it compares to reaction wheels.
By using this calculator: :

A force of 20 kN (juno) with a length of 9 m which is about half the length of this craft or the distance from the CoM, we have a torque of 180 kN/m. The biggest reaction wheel has 30 kN/m so 180 / 30 = 6. So a single juno on the tail of this particular craft generate as much torque as 6 of the biggest reaction wheels if I’m not mistaken. The reaction wheel weight 0.2t while a juno + the elevon have a combined weight of 0.29t.

Update: This has a disadvantage compared to reaction wheel in that the control authority depends on the throttle so if your throttle is low then you have reduced control.


A stock aircraft called Jet RCS Demo. Built with 45 of the finest parts, its root part is mk3Cockpit.Shuttle.

Built in the SPH in KSP version 1.3.1.


  • Type: SPH
  • Class: aircraft
  • Part Count: 45
  • Pure Stock
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