Controlled Aerobraking?

[Stubby]

With the new preview showing off the air brakes, a neat concept popped up in my head; a way to control aerobraking without using any fuel!

Basically, there will be four air brakes symmetrically attached around the craft. Two opposite brakes will be open, and the other two will be closed. When you enter the atmosphere and find yourself going too fast, you can open up two more brakes and further slow yourself down. But if you're going too slow and heading too far down, you can close the two open brakes and lessen the drag. Assigning the action groups might be tricky, but it could be very useful.

I don't know if it's feasible or not, but I'm definitely going to try when 1.0 is released!

[Zephram Kerman]

Makes sense. Although a simpler way would be to put all your brakes on one action group, then open and close them as needed during the maneuver. Your way would work too, and probably look more interesting too. Normally I do this with wings, by changing pitch to control drag, a-la the space shuttle. But a small capsule could use air brakes to get a similar effect. Cool!

[Temeter]

It's been a while since I used airbrakes, but placing them atop the rear seemed to work best in normal flight situations (reentry/before landing). Afair it was because the nose gets pushed up a bit, which increases the drag even more and keeps the plane from diving.

Symmetrical brakes can help dealing when your plane is oscillating, tho. Generally depends on how Squad is going to implement airbreaks, FAR e.g. nerfed them quite heavily at one point, mostly for realisms sake, since they could brake a plane better than wheels.

Edited April 25, 2015 by Temeter

[arq]

I am a glider pilot. When landing the standard practice is to run 50% spoilers during approach and landing. That way you can let the spoilers in or pull them out to change your rate of descent so that you hit your landing (and if you are still too high you can do more dramatic maneuvers like a sideslip).

While this same procedure would work as you describe for re-entry, without additional controls to help steer the craft you're pretty much stuck on a ballistic trajectory. You can change your rate of deceleration, but you will have a hard time aiming if you're just using this one control. In general the best way to get the re-entry you want is to modify your re-entry speed and angle before you hit atmo.

In general I expect you'll be fine using just 0% and 100% brakes, though it still might be neat if there were a toggle to switch your throttle control to a brake control. The usefulness of all of this will very much depend on the details of the 1.0 aerodynamics.

[Kerbolnaut]

In general I expect you'll be fine using just 0% and 100% brakes, though it still might be neat if there were a toggle to switch your throttle control to a brake control.

Maybe make it so that while brakes are toggled on, they are automatically applied at the opposite of your thrust toggle? 0% thrust = 100% brakes, 75% thrust = 25% brakes, etc. This could be very handy when landing a spaceplane, since airbrakes should be more effective as you go faster, and less effective as you go slower, but engine thrust is constant. It would make it so that you'd rapidly speed up or slow down to a certain equilibrium speed whenever you change the throttle settings, so when your brakes are on your throttle would act like a speed controller rather than just acting strictly as an accelerator.

[mattinoz]

To bad we don't have notchable setting for this sort of thing.

If you we could tap B to increase brakes and mod(alt/option) B to decrease then we could have just one key give a range of control.

Holding the B down would quickly set brakes to 100% very quickly anyway.

[merendel]

If your just looking at breaking but remaining on an orbital trajectory (aka aerocapture or lowering your AP) you can also just use wings and vessle pitch to controll things. if you have wings and nose down while near your PE they will be generating "Lift" that will be pushing your craft back to the planet. Asumeing you are sufficently deep enough for the wings to bite into the airflow you can use this technique to hold yourself in a thicker part of the upper atmosphere to slow down more in a single pass. you could also nose up if you feel your going too deep to slow your vertical decent. Dont really more traditional air breaks to pull that off.

[Flayer]

I always did this in previous versions of KSP by turning the craft sideways...

[rkman]

Should only works if air brakes have ablative shielding.

[magnemoe]

Should only works if air brakes have ablative shielding.

They don't but might still work well at least if you pump them on and off, it looks like they brake a lot at least at lower speeds, the new radial braking parachutes did so to, not sure how well they will work on large crafts, they might well overheat in a few seconds.

Note that any of this will not save fuel, just make it easier to survive reentry.

[panzer1b]

I dont mind either ay, nice addition but its not like you cant angle your craft to begin with (i usually pitched up to slow down quickly). Still, im defenetely going to use them as emergency unflippers, when for whatever reason my terribly designed craft goes nose backwards, and im too close to the ground to save myself the old fashioned way.

[Fearlessjames118]

I like the way you think Stubby! I might actually use this when....you know.....it's out

[lajoswinkler]

Flaps we're getting are not for reentry. Reentry can not be survived with anything but blunt shaped, ablative surfaces. It's not few Machs in real life. It's reentry.

The only proper way to control it is to tilt your vessel.

[magnemoe]

Flaps we're getting are not for reentry. Reentry can not be survived with anything but blunt shaped, ablative surfaces. It's not few Machs in real life. It's reentry.

The only proper way to control it is to tilt your vessel.

http://nassp.sourceforge.net/w/images/5/59/Command_Module_Aerodynamics.png

Current craft

Disagree with you

Pretty sure the shuttle used controlls during reentry. Now pods has the benefit of beeing small, light and have few failure points.

Dragon heat shield is also reusable, its also ablative but not very much, link says it could be used for moon or mars return, in this case its probably not reuseable.

http://www.spacex.com/news/2013/04/04/pica-heat-shield

[Robotengineer]

Current craft

http://www.thelivingmoon.com/41pegasus/04images/Russian/Shuttle_01/Buran41.jpg

Disagree with you

Pretty sure the shuttle used controlls during reentry. Now pods has the benefit of beeing small, light and have few failure points.

Dragon heat shield is also reusable, its also ablative but not very much, link says it could be used for moon or mars return, in this case its probably not reuseable.

http://www.spacex.com/news/2013/04/04/pica-heat-shield

The shuttle didn't use airbrakes during the reentry phase AFAIK. If it did, the brakes would probably just break off, or cause extreme deceleration.

[lajoswinkler]

Current craft

http://www.thelivingmoon.com/41pegasus/04images/Russian/Shuttle_01/Buran41.jpg

Disagree with you

Pretty sure the shuttle used controlls during reentry. Now pods has the benefit of beeing small, light and have few failure points.

Dragon heat shield is also reusable, its also ablative but not very much, link says it could be used for moon or mars return, in this case its probably not reuseable.

http://www.spacex.com/news/2013/04/04/pica-heat-shield

No, Space Shuttle did not use that. It used those flaps when landing, but during reentry it was behaving as a blunt body ramming through rarified air. It could do some pitching, though, by thrusting through nozzles on its nose.

[spaceman1999]

This may sound stupid but can we do a challenge that involves landing a capsule only using air brakes instead of a parachute?

[Zephram Kerman]

Landing a capsule with only air brakes and no parachute would be... yeah, "challenging". They become less effective as speed gets slow enough to survive touchdown. So it would require very many of them, to the point that the craft is actually a parachute made of airbrakes.

However, doing that with wings, well that happens every day.

[spaceman1999]

I was thinking of danny's invasion device.

[lajoswinkler]

This may sound stupid but can we do a challenge that involves landing a capsule only using air brakes instead of a parachute?

We could try to spam them, turn a capsule into a flower.

It probably won't work because of the reasons Zephram told.

[BDelacroix]

What we need is a speed hold control. Either hold on throttle and use air brakes.

[MalfunctionM1Ke]

Two opposite brakes will be open, and the other two will be closed. When you enter the atmosphere and find yourself going too fast, you can open up two more brakes and further slow yourself down.

I wonder if you can steer that way... That would be cool

[Wallygator]

I think these "air brakes" could be used to right a rover which has flipped.