Increased engine gimballing

[Daze]

It's some time that i think that an increased thrust vectoring should absolutely came into the game. I was watching some photos of Astra 1KR launch with an Atlas V + 1 SRB and i was wondering how beauty and useful could be to make the same thing, another thing is that with an increased gimballing we can finally see the stop of the SAS-spam in STS launch vehicle and also more versatility during the positioning of payload.

[Tex]

Hmm... Do you want all engines to have an increased vector range, or just a new type of engine with a large vector?

I'm in favor of this second option. Not many real-life engines have great gimballing ranges, but the STS main engines had a fantastic gimbal range (something like 30 degrees!) to offset the SRB thrust and the weight of the external fuel tank.

[PlonioFludrasco]

Never heard of asymmetic rockets except STS and Energia. cool stuff, +rep.

Anyway, was that Atlas V supposed to fly with just 1 SRB or someone forgot to switch to symmetry mode?

Back on topic, yes, it will be very useful to have such an engine.

edit: I mean dedicated engine

[KrazyKrl]

LV-T50 engine maybe?

Cost: 1,250

Techlevel: Advanced Rocketry

Mass: 2.0 t

Max Thrust: 200 kN

ISP: 320(ASL)/370(vac)

Vectored thrust limit: 20 Degrees

Essentially a 30% heavier LV-T45 with a higher techlevel and credit cost. 500kg additional weight needed for control mechanisms, and reinforcement, sounds like a reasonable trade.

The heavier crafts don't really need lots of thrust vectoring; RCS/control surfaces/magic wheels, would probably be a better option.

[Frozen_Heart]

We've needed a high gimbal SSME for ages. Both a 1.25m version and a 2.5m version.

At the moment clipped SRBs and lots of reaction wheels work but that's an imperfect solution.

(While we're at it, make it so the thrust curve of SRBs can be set in the VAB so it can decrease over time)

[BudgetHedgehog]

Anyway, was that Atlas V supposed to fly with just 1 SRB or someone forgot to switch to symmetry mode?

Wasn't supposed to per se, it was just capable of it. The main engine had the gimbal to cope with the offset thrust (I think about 8 degrees?). The reason they're asymmetrical in the first place is because it had set mounting points for LOX and various fuel lines at 10.30 and 1.30 positions. So they only had limited places to put SRBs on that weren't at these places. Here's a video of ASTRA 1KR launched on it's Atlas V with 1 SRB.

Back on track, yes, I'd like more gimbal on KSP engines. Not necessarily just one engine with wide gimbal range, just a general increase in it. They'd have to write a new gimbal code though as things get a bit funky above I think 8 degrees so yeah.. increased gimbal and use gimbalResponseSpeed too! Both those things would be lurvely.

[Bill Phil]

Why not a gimbal platform that acts as a seperate control part? Kind of like the ARMs Klaw...?

[Renegrade]

I'm in favor of this second option. Not many real-life engines have great gimballing ranges, but the STS main engines had a fantastic gimbal range (something like 30 degrees!) to offset the SRB thrust and the weight of the external fuel tank.

Actually only about 8.5 to 10.5 degrees (depends on direction) for the Space Shuttle Main Engines and 8 degrees for the solid rocket boosters.

Still, that's a lot better than the 0.5 to 1.5 that's typical for most stock liquid fuel engines (leaving out the Mk55, which has a full 5 degrees, and the fixed engines), or the 0.0 to 0.0 degrees that the stock solid fuel engines have.

There was talk of unlocking upgrades for parts in a previous thread (something I strongly support); having configurable tech parts (kinda like realfuels) would allow for easy addition or removal of gimballing capabilities with mass/cost tradeoffs via tweakables.

Why not a gimbal platform that acts as a seperate control part? Kind of like the ARMs Klaw...?

I'd much rather have a tweakable system like I mentioned above. A dedicated platform would increase the wobble in a stack (wobble is basically a function of the number of links in a stack), and also additional part lag.

[Daze]

I would like a general improvement.

It definitely be in the game with the balancing of 1.0 (imo)

[GusTurbo]

More gimbal would be useful. One of the problems with high gimbal engines in KSP is that the engine gimbals move very quickly in the current system, if not instantaneously. This has two issues: 1. the engines move really quickly back and forth to try to stabilize, causing wobble, and 2. it looks downright strange when you have higher gimbal range. I've modeled an engine for this game and gave it a 5 degree gimbal range, and it looked ridiculous as it shook my rockets all over the place. They would have to implement some sort of programming to make the gimbal move at a limited rate.

[ferram4]

That code (response time) already exists in the stock gimbal code, it simply isn't used. Further, SAS isn't set up to be aware of it either; this is something that can easily be set up though, it's very simple control theory to account for that, since they did actually model it using a proper 1st-order system. Hell, Realism Overhaul uses that for its engines, and many of those get about 7 degrees of deflection and they behave just fine (even under SAS's control).

There are no compelling reasons for why the gimbal ranges are as low as they are. There are really only two reasons, and both of them have better options than limiting gimbal range:

1) It reduces wobble.

This problem can be solved by stiffening up the joints further. Also, I recall Harvester talking about how they thought that some wobble was "fun" and so were leaving it in, and if it's fun, I don't see why removing wobble is desirable. In any case, making use of the already-existing response time code fixes that quite well.

2) SAS can't cope and introduces control-induced oscillations.

This problem can be solved by making SAS aware of the way gimbals, control surfaces, etc. respond. This is already a solved problem in control theory, nothing difficult at all. It even opens the possibility for mods to hook in (if it's done right) so that SAS is aware of pretty much any method of controlling vehicles. Low gimbal ranges shouldn't be used to hide SAS's shortcomings.

[Rath]

STS boosters had something like 5degrees of gimbal too- it's perfectly reasonable to have gimbaled SRBs

- - - Updated - - -

You could call a 2.5 meter high gimbal engine the tiller to keep with the sailing theme

[Daze]

So as you said Ferram the only real problem is that Squad doesn't want, not because there's limited software possibilty and maybe (i hope not) for "too much realism, our game is about fun!!!1"?

[bartekkru99]

Only some of the engines should have higher gimbal range.

[rkman]

One of the problems with high gimbal engines in KSP is that the engine gimbals move very quickly in the current system, if not instantaneously. This has two issues: 1. the engines move really quickly back and forth to try to stabilize, causing wobble

I'm pretty sure there is (or at least used to be) a gimbal movement speed tweak in stock ksp.

Aside from that, i've had more success with stabilizing wobbly rockets by decreasing gimbal range than by adding sas/reaction wheels.

[Woopert]

I'm in favor of this second option. Not many real-life engines have great gimballing ranges, but the STS main engines had a fantastic gimbal range (something like 30 degrees!) to offset the SRB thrust and the weight of the external fuel tank.

Actually, it's the opposite of that Most real life engines have gimbal ranges around 2-4 times greater than KSP. The F-1 engine had a range of 6 degrees, the SSME a range of 10.5 degrees for pitch control, etc.

The four engine cluster engine in KSP has a gimbal range of 0.25, which is utterly ridiculous because it gives you so little control over the rocket. Similarly, I would like to see SRB's be given gimbal capability as we'll. Many real life SRB's have gimballing and in the case of the STS, they were vital for the functioning or the system. Before booster separation they actually had to null the position of the SRB gimbals.

Cheers

Edited March 8, 2015 by Woopert

[Daze]

Another 2 things:

1) SRB ABSOLUTELY need engine gimballing, it's crazy that they are full uncontrollable, yes guys it's "KSP style moar booster boom boom" but please...

2) We don't need gimbal like the RS-25 but at least something like 5-6° for the most of the engine

[Daze]

Oh and actually it's funny that we have STS parts (Mk3) but we don't have the real way to make them works nice ahah

[Ullax]

it's true, i want the same thing!

[Daze]

I would like to hear other opinion about this

[SlabGizor117]

More gimbal would be useful. One of the problems with high gimbal engines in KSP is that the engine gimbals move very quickly in the current system, if not instantaneously. This has two issues: 1. the engines move really quickly back and forth to try to stabilize, causing wobble, and 2. it looks downright strange when you have higher gimbal range. I've modeled an engine for this game and gave it a 5 degree gimbal range, and it looked ridiculous as it shook my rockets all over the place. They would have to implement some sort of programming to make the gimbal move at a limited rate.

Yeah, but it deals with control surfaces and fins well, also I've noticed the fine control mode(Caps) on RCS thrusters would work, how you tap it and it nudges it a tiny bit, or you hold it and it builds up to full power. That would probably work for gimbal on engines. Yes, as it is now, gimbaling(sp?) engines move instantaneously if not very fast, but you could fix that, and it would cover both the problems of wobble and aesthetics. I mean, the SSMEs don't look stupid with, what 10? 20 degrees of gimbal? 'Cause it's gradual

[BudgetHedgehog]

The code to gimbal gradually already exists in the stock game - it's useGimbalResponseSpeed = true with gimbalResponseSpeed = [number]. High values (like 10) make it quicker, lower values like 3 or 4 make it slow to respond. Squad just needs to use it. It's right there, sitting and waiting to be used for something and it just isn't. They don't need to code anything more or redo the animations, it's literally 2 extra lines in the engines config.

EDIT: Although, as ferram4 said on the previous page, SAS currently isn't aware of it (though it's an easy fix).

Edited March 17, 2015 by ObsessedWithKSP

[SickSix]

Either apply more gimbal to higher tier stock engines or introduce an STS line of engines with high gimble and use the existing code for the speed as stated. It is really silly that you can max the tech tree and still have nearly zero gimble ability.

[Wabbit]

I want small radial verniers, with now thrust but very high vector-ability... No, not vernor RCS!

[Daze]

The little gimballing we have now it's simply silly, no way.

I still don't understand why SRB have no gimbal at all...