Using Airbrakes to maneuver?

[Chakkoty]

Watching the 3-part starbase tour got me thinking - the airbrakes in stock KSP fold against the hull and can then be extended outward. 

What if using them to aerobrake was their secondary, not primary function? Theoretically, by adjusting their angle only slightly, air flow can be directed away from the hull and used to "steer"  the landing booster, with fully extending them to aerobrake only being used in emergencies when the booster is coming in literally "too hot"?

I need someone more knowledgeable about aerodynamics to tell me either "Huh." or what a stupid idea that is. 

[RCgothic]

You mean replacing the grid fins on Superheavy/F9 with KSP style airbrakes?

[Chakkoty]

6 minutes ago, RCgothic said:

You mean replacing the grid fins on Superheavy/F9 with KSP style airbrakes?

Not specifically on those rockets, but yes. Of course the airbrakes would have to hug the hull much more snugly so that they cause little to no air resistance. They could serve as simple airbrakes when it's absolutely necessary by fully extending them, but first and foremost to direct airflow away from the hull to steer during reentry. This would of course create small turbulances behind the brakes and is probably a very non-optimal way to do this, but I just have to know if it would at least be feasible.

[ColdJ]

I have used KSP Airbrakes to have some maneuvering on small things but they don't have much affect on large things. You would have to custom config a new airbrake with much greater deflection to have any real affect on anything of significant size.

[Chakkoty]

3 minutes ago, ColdJ said:

I have used KSP Airbrakes to have some maneuvering on small things but they don't have much affect on large things. You would have to custom config a new airbrake with much greater deflection to have any real affect on anything of significant size.

Thanks, that's all I wanted to know! So it is possible to use airbrakes for maneuvering during descent, just not with the KSP airbrakes?

[ColdJ]

8 minutes ago, Chakkoty said:

Thanks, that's all I wanted to know! So it is possible to use airbrakes for maneuvering during descent, just not with the KSP airbrakes?

Not with stock ones. I know that there are some mods out there that offer other sizes, but I haven't tried them. It is the module in the config that determines how mush they affect air flow when used. This is what it looks like. I will bold the parts that are used to calculate. Remember if you try to make your own part, always "SaveAs" another name before you change anything and then change "name =" to something unique to you. Also change "title =" to something else so you know which part is yours in the parts list.

    MODULE
    {
        name = ModuleAeroSurface
        useInternalDragModel = True
        dragCoeff = 0.6
        deflectionLiftCoeff = 0.38
        ctrlSurfaceRange = 70
        ctrlRangeFactor = 0.2
        ctrlSurfaceArea = 1
        actuatorSpeed = 20
        transformName = Flap
        defaultActionGroup = Brakes
        liftingSurfaceCurve = SpeedBrake
        ignorePitch = true
        ignoreYaw = true
        uncasedTemp = 1200
        casedTemp = 2400
    }

Edited September 20, 2021 by ColdJ

[Chakkoty]

5 minutes ago, ColdJ said:

Not with stock ones. I know that there are some mods out there that offer other sizes, but I haven't tried them. It is the module in the config that determines how mush they affect air flow when used. This is what it looks like. I will bold the parts that are used to calculate. Remember if you try to make your own part, always "SaveAs" another name before you change anything and then change "name =" to something unique to you. Also change "title =" to something else so you know which part is yours in the parts list.

    MODULE
    {
        name = ModuleAeroSurface
        useInternalDragModel = True
        dragCoeff = 0.6
        deflectionLiftCoeff = 0.38
        ctrlSurfaceRange = 70
        ctrlRangeFactor = 0.2
        ctrlSurfaceArea = 1
        actuatorSpeed = 20
        transformName = Flap
        defaultActionGroup = Brakes
        liftingSurfaceCurve = SpeedBrake
        ignorePitch = true
        ignoreYaw = true
        uncasedTemp = 1200
        casedTemp = 2400
    }

Oh. I meant in real life. May have been a bit unclear, sorry.

[ColdJ]

 

3 minutes ago, Chakkoty said:

Oh. I meant in real life. May have been a bit unclear, sorry.

Yep. was unclear. Yes in real life this is already a thing. Airbrakes fit in smoothly to the skin when not being used.

[RCgothic]

For steering at hypersonic speeds grid fins are far more mass efficient, require smaller actuators, less power etc.

I believe the proposed New Glenn uses a different "strakes" method of deflecting the airflow.

[DDE]

Not sure about descent, but I've certainly used them during ascent.

[Chakkoty]

Alright, thanks!

[lrd.Helmet]

Most large airliners use their inner spoilers/speedbrakes/airbrakes on their wings to roll at higher speeds. The regular ailerons are pretty far away from the center of mass and therefore have a large momentarm, by using the spoilers this distance is greatly reduced and as such the forces are as well.

Using the spoilers also reduces yaw effects (you'd normally have when using ailerons) when the rudder authority is reduced due to high speeds 

Edited September 20, 2021 by lrd.Helmet
more stuff

[mikegarrison]

9 hours ago, lrd.Helmet said:

Most large airliners use their inner spoilers/speedbrakes/airbrakes on their wings to roll at higher speeds. The regular ailerons are pretty far away from the center of mass and therefore have a large momentarm, by using the spoilers this distance is greatly reduced and as such the forces are as well.

Using the spoilers also reduces yaw effects (you'd normally have when using ailerons) when the rudder authority is reduced due to high speeds 

Yup. I was going to post this, but you already did.

[monophonic]

I'll also throw in the AMaRV or Advanced Maneuverable Re-entry Vehicle. It was a nuclear warhead the USAF developed in the seventies and flight tested at the turn of the eighties but never fielded. It used flaps not entirely unlike KSP airbrakes to pull hairpin turns at hypersonic speeds.