Winglets: Useful or waste of space?

[zapman987]

Are winglets generally useful at all for rocket launches? Big or small I cant get much out of them.

Edited November 12, 2013 by zapman987

[austin4050]

They are only useful when at high gravity (aerodynamic stuffs) Think of them as RCS but while in the atmosphere. You should equally space/place them although make sure that you have enough compared to the weight of your craft.

[Superfluous J]

The basic ones aren't worth the tinfoil they're made out of. The tiltable ones work okay for a launch stage but frankly I skip 'em. I put enough reaction wheels on my rocket for orbital maneuvers to not be painful, and those are more than enough to turn my craft 90 degrees to the east during an 80 kilometer ascent.

[SSSPutnik]

I was reading somewhere that only one reaction wheel / SAS is required for any ship? True or not? (Yes a large one helps larger ships but the post implied only one is required).

(Unless of course it gets jettisoned in a stage I guess).

(From the FAQ: "What's the difference between S.A.S and Advanced S.A.S?

With version 0.21 there is no difference between them anymore. The previous function of ASAS to hold the heading was moved to the SAS while the SAS instead became reaction wheels which provide torque. Like before with ASAS only one SAS module per ship is required, its performance depends on amount and positioning of the control systems like RCS.")

[TheDarkStar]

I was reading somewhere that only one reaction wheel / SAS is required for any ship? True or not? (Yes a large one helps larger ships but the post implied only one is required).

(Unless of course it gets jettisoned in a stage I guess).

(From the FAQ: "What's the difference between S.A.S and Advanced S.A.S?

With version 0.21 there is no difference between them anymore. The previous function of ASAS to hold the heading was moved to the SAS while the SAS instead became reaction wheels which provide torque. Like before with ASAS only one SAS module per ship is required, its performance depends on amount and positioning of the control systems like RCS.")

Only one is required because there tends not to be a time when you need to have a lot of turning force. Gimballed engines are good for when you are in the atmosphere, RCS for sudden turns and corrections when landing or setting an intercept, and one SAS for general turning. Gigantic or non-balance ships might require more.

[SSSPutnik]

OK, thanks for tip. (Sorry to but in OP).

[zapman987]

All good Its a good question for me to remember. Funny as I normally put in 2 or 3 on my ships, about one for each stage.

[Vanamonde]

Winglets are the most effective way to control unwanted roll during launches, which is otherwise hard to deal with because neither RCS nor reaction wheels cope with it well. Other than that, winglets have no utility for rockets that I can think of.

[HeadHunter67]

The kind that steer? I use them on my first stage for some extra aerodynamic control during initial ascent. Just make sure you have the right size for your rocket.

[thereaverofdarkness]

I put in one canard for every large rocket stack with 6400 fuel (orange tank) or more. I use AV-R8 winglets for medium rocket stacks. I find that the pivotable winglets are easily the best control source for rockets launched from Kerbin, beating reaction wheels significantly and RCS dramatically. The winglets start to lose control around 30,000 to 40,000 meters, depending on your ascent velocity, and will lose control rather suddenly because of the way the air thins exponentially faster and faster as your rocket accelerates. Sometimes I discover at 35,000 meters that my winglets were holding my rocket together--while watching the thing perform sudden unplanned disassembly.

[Vanamonde]

The passive ones will also reduce roll, but yes, I was thinking primarily of the active ones.

[Frederf]

Winglets is a weird term because it's usually small surfaces at the end of airplane wings. Static fins are nice to enforce positive stability aerodynamically. Control surface fins are nice to provide control aerodynamically. Your most drivable craft might use one or the other or a combination.

I find FAR a welcome addition because I can disable the roll control channel from the aero surfaces as they are much much too sensitive in roll (causing SAS to spaz out in oscillation).

[jwilhite]

If you are using engines with thrust vectoring, you don't typically need the winglets. However, if you are using those LV-T30 engines and solid boosters, you really need winglets because none of your engines gimbal to control your direction.

[CumpyLustard]

The AV-T1 winglet is pretty useless in my experience, but the AV-R8 winglet does seem to help my shoddy craft make their way into space!

[Vanamonde]

If you are using engines with thrust vectoring, you don't typically need the winglets.

Since all engines pivot in unison, thrust-vectoring has no effect at all on roll. But yes, winglets are largely redundant for steering on the other two axes.

[kurja]

I was reading somewhere that only one reaction wheel / SAS is required for any ship? True or not? (Yes a large one helps larger ships but the post implied only one is required).

I've been meaning to post about those large sas units - why should I use them? They weigh more than the small reaction wheels but provide exactly the same torque, so why not use the smaller ones instead..?

[Rhomphaia]

I've been meaning to post about those large sas units - why should I use them? They weigh more than the small reaction wheels but provide exactly the same torque, so why not use the smaller ones instead..?

Actually they weigh less. 0.2 vs 0.3 for the inline reaction wheel and 0.5 for the inline advanced stabliser

[allmhuran]

Winglets are the most effective way to control unwanted roll during launches, which is otherwise hard to deal with because neither RCS nor reaction wheels cope with it well. Other than that, winglets have no utility for rockets that I can think of.

Very much this. If you are building large rockets with many radial boosters, particularly in asparagus configuration, you will quite often get unwanted roll when you make attitude changes, and thrust vectored engines cannot fix unwanted roll (in the game), so you're left with reaction wheel / command pod torque only. Winglets, even very small ones, provide fantastic roll correction.

EDIT: By the way, if you are considering putting LVT45's on a lifter stage, always change your mind and put LVT30's and winglets instead. You need the winglets because the LVT30's aren't thrust vectored, but they weigh less than the LVT45 and have higher thrust. (1.25 vs 1.5 mass, 215 thrust vs 200, identical ISP)

Edited November 12, 2013 by allmhuran

[kurja]

Actually they weigh less. 0.2 vs 0.3 for the inline reaction wheel and 0.5 for the inline advanced stabliser

They do? Oh shoot, I must have been looking at drag figures or something. Hm according to wiki large one weighs 0.2, small advanced stabiliser & reaction wheels weigh 0.5. But.. large one weighs less? That makes even less sense. I'll rephrase then - why would I use the small one?

[Rhomphaia]

They do? Oh shoot, I must have been looking at drag figures or something. Hm according to wiki large one weighs 0.2, small advanced stabiliser & reaction wheels weigh 0.5. But.. large one weighs less? That makes even less sense. I'll rephrase then - why would I use the small one?

The wiki needs updating, the table on the stock parts page gives the 0.21 value for the "Inline reaction wheel". the individual pages give the 0.18 values for the "Advanced sas module, large" and the "Inline advanced stabilizer".

As to why you would use the smaller ones over the large, looks is the only reason just now.