Steerable fins in real life.

[KSK]

Move over Kerlington. Here's how you do it!

http://www.universetoday.com/112702/video-spacex-tests-new-steerable-fins-on-the-falcon-9r/

[Duxwing]

Listen to that Merlin purr!

-Duxwing

[ultrasquid]

There is a grid fin similar to those in the video included with the Kerbonov Kn-2 pack by Sam Hall. They don't retract, but an Infernal Robotics hinge ought to be able to rig that up if you want it.

[vger]

Dang, wish I could execute a control thrust like that so close to the ground and so efficiently.

I started getting KSP "lander anxiety" as soon as the ground started to draw closer.

[Nuke]

i bet them cows were scared.

i guess they are there for the victory bbq.

[Nibb31]

Seems like a great way to fix the roll problem that killed the CRS 2 booster.

[Tommygun]

Didn't realize those grid fins were so maneuverable.

I was thinking they were just mainly used as dive breaks.

[sgt_flyer]

Grid fins are used a lot when you need to fold fins to limit the shape size. A lot of russian stuff use grid fins, including some real rockets - the N-1 rocket had huge grid fins, and current manned soyuz have grid fins mounted on the fairing - they are deployed in case of abort. UR-700 and UR-900 concepts made use of grid fins too

One other advantage of grid fins is the low torque needed to control them - allows for much smaller servos than standard steerable fins.

The downside being the increased complexity - as you need to include a reliable way to deploy them

Edited June 19, 2014 by sgt_flyer

[Nibb31]

And yet another advantage is that they work through a whole lot of flight regimes, including hypersonic regions.

In this video, below a certain speed, they pivot clockwise and anti-clockwise to induce roll or yaw and pitch. It looks like at higher speeds, they seem to pivot up and down to act as flaps and/or airbrakes, which makes sense because the grids are less effective at those speeds. The computer probably chooses either mode depending on the airspeed.