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micha

KV-1 Onion pod, how to launch?

Question

So I only recently got the Making History expansion, downloaded 1.5.0, and started a brand-new game, no mods.

For larks I decided to use the Onion pod for the early missions instead of the Mk1. And I just can't get the darned thing into space.  Basic rocket  Onion, bunch of tanks, and an LV45 engine (oh, and some basic (non-steerable) fins on the bottom-most tank). Rocket flips once I get to about 10k or so. Throttling down, adding more/bigger fins, etc only delays the inevitable. I just can't stop it flipping once I get above a certain altitude.
Same rocket but with a Mk1 pod instead makes space no problems.

So am I doing something wrong, or does the KV-1 need to be in a fairing to launch (ie, historically accurate)? If the latter, what's the point in making it available so early in the game without also giving us the corresponding fairings?

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The MK1 is pointier so it is more aerodynamically stable than the "onion" pod. You can compensate for this by flying really carefully though and do the gravity turn very gradually. This will be less efficient but at least it won't flip over so easily. It might help to somehow make the rocket longer as well, as it'll get a slimmer profile and the longer rocket body will act as a "sail" and counteract the drag of the pod.

 

Maybe post a screenshot of the rocket you're having trouble with?

Edited by Mjarf

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I think the basic point is that the KV-series pods have no reaction wheels. To use them and keep them going straight in the lower atmosphere is easy -- you just need steerable fins. Once the atmosphere thins out enough that steerable fins won't steer, then you almost certainly need to use a gimballed engine. Meaning the Swivel. Beyond that, probe cores have tiny little reaction wheels in them, that may be enough to keep you going straight -- maybe. Alternately, you need to research RCS and turn it on while you are still in the atmosphere. All of which comes together to say: yes, you need to add something else to the rocket to give you control authority.

So did you lock the gimbal or reduce the gimbal authority on your engine?

And if your rocket still flips with full gimbal control, that generally means that you are going too fast -- because you are getting too much drag at the front end of your rocket.

Edited by bewing

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19 minutes ago, bewing said:

I think the basic point is that the KV-series pods have no reaction wheels.

 

Lol, ok, I missed that! Still, the LV45 (ah yes, it's called the "Swivel" now..) is a gimballing engine which gave me enough control authority early in the flight, so no steerable fins required. And no, I did not adjust the gimballing on the engine; just bolted everything together and hit launch.

I wonder if it's a combination of it being a lighter and less aerodynamic part as well as not having gimbals that causes the flips once there's less air pressure for the fins?
I figured once I got through MDP I'd be golden but the problems seem to occur just after the rocket enters the upper atmosphere. I did manage to recover the rocket sometimes but by then I'm out of velocity and fuel to make it to space. At least no Kerbals died in these attempts (so far)...

ED1:

..but then if you need some additional control authority, my point stands, why give us this pod so early without the necessary bits to use it?

 

ED2: (To reply to your redit):
Heh, yeah, my caveman days are long ago, I need to re-learn the fine skills I had required then to nurse this up. Just seems a bit pointless considering we have the much more capable Mk1 pod available at the same time.

Edited by micha

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6 minutes ago, micha said:

..but then if you need some additional control authority, my point stands, why give us this pod so early without the necessary bits to use it?

 

ED2: (To reply to your redit):
Heh, yeah, my caveman days are long ago, I need to re-learn the fine skills I had required then to nurse this up. Just seems a bit pointless considering we have the much more capable Mk1 pod available at the same time.

But you do have enough bits :)-- with careful engineering and flying. With enough drag at the back, and some AV-R8 steerable fins, and an LV45 engine, and lower drag at the front, you can do it. Did you notice that there's a node on the top for attaching an MK16 parachute? If you left that node open, that could easily be a cause of the flipping.

And as far as the MK1 goes: some people consider it to be OP with the "magic" reaction wheels and all. So the Onion pods are lower tech than the MK1 pod. So we can't put it higher in the tech tree now can we? ;) 

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Yes I do have a Mk16 parachute on top (how else to return in the early game?); but no you don't have enough bits in the early game. Steerable fins are way down the tech tree (at least 3 nodes) so we don't have those by the time we try to make it to space (second or third launch usually, unless you grind out all the local science first by which point you'll probably have access to far more capable pods anyway).

I'll just have to practice flying a bit more with this pod; was just surprised at how much worse it was than the Mk1 but the lack of reaction wheels and different aerodynamics could account for that.

The tech tree doesn't really make sense anyway from a tech/realism perspective. Not even sure from a game perspective. It just seems to be what it is because that's how it evolved during development.

Anyway, thanks, I think the core point I had overlooked was the fact that the Onion doesn't have reaction wheels. I'll try turning them off on the Mk1 to see how much of a difference they make.

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Ok, a longer rocket helped. A lot. I barely had to throttle down.  Not only did I make it to space, but also orbit (with a second stage).

Still, I'll be glad to unlock RCS/reaction wheels!

 

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9 hours ago, bewing said:

Did you notice that there's a node on the top for attaching an MK16 parachute? If you left that node open, that could easily be a cause of the flipping.

Sticking a Mk16 chute on top makes little or no difference because it doesn't match the mesh of the Onion. 

To reduce drag to a level that will make the Onion useable you will need something like this (or a fairing)...

29LdIqj.png

Let's be honest...the Onion, Pea and Pomegranate are useless apart from some historic recreation purposes. 

Edited by Foxster

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In my game the Onion is essentially a test bed for crewed pods and use for landed and low atmosphere crew reports. It's fun to boost out over the water using an SRB, but I don't even try to accelerate it to even sub-orbital speeds. it's just not aerodynamic.  If there was a 1.25m fairing available earlier I might consider doing a Vostok style launch.

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The Onion / Pea / Pomegranate look neat and all, but I find that in my own games, I never, ever use them, simply because there's no good use case for them-- especially since they don't have reaction wheels, which is pretty much a deal-breaker for me.

From time to time I've thought about just using ModuleManager to patch in some reaction wheels on them... but the only reason I haven't is that although having reaction wheels might make them usable for me, I just don't have a good reason for it when there are perfectly serviceable (and more conveniently shaped, and more aerodynamic) alternatives.  So they end up just languishing in the editor and never getting used.

I wish there were some way to give a reason for using them, because I think they do look cool and I'd love to have a reason to use them.  It's just that I haven't been able to find one.

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Maybe they could either reduce the cost so it could function as a low cost alternative to the MK-1 or perhaps increase the temperature limits so it'll be more useful as an emergency re-entry pod for a station or something?

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11 minutes ago, Mjarf said:

Maybe they could either reduce the cost so it could function as a low cost alternative to the MK-1 or perhaps increase the temperature limits so it'll be more useful as an emergency re-entry pod for a station or something?

Response in spoiler because we're kinda derailing the thread, here-- this thread's about "how do I use these pods on a ship without flipping," not a critique of their design.  ;)

Spoiler

That wouldn't solve the problem, for me.

The existing "useful" pods are already pretty darn cheap-- not least because they tend to get recovered anyway.  When playing in career mode, the money drain is upgrading buildings and such, not "spending it on command pods".  They could reduce the cost of those pods to zero and I still wouldn't have any reason to use them.

They could increase the temperature, sure-- or even give it a bit of built-in ablator, which would be even better.  But again, for me at least, that wouldn't be enough to make them worthwhile.  A Mk1 pod can already survive reentry from LKO without a heat shield.  And if you stick a 1.25m heatshield on it, then it can survive pretty much any reentry you care to try.

I'll drop that train of conversation now-- I suggest we get back on topic.  ;)

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snark -- they *do* have built-in ablative. Because they are supposed to be able to reenter directly from the Mun.

 

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.. and as I said, with a touch more practise and a longer rocket I could get it to orbit so my question was answered.

Still, ideally you'd get other relevant tech (rcs, fairing) along with it to make a Vostock/Voskhod style launcher.

And yes, apart from the sheer novelty as an alternative to the Mk1 it's hard to justify why you'd use them. Although you do get the 2-Kerbal one earlier than the Mk2 along with reaction wheels so potentially a rescue pod?

Shame they didn't include Soyuz styled capsules as a follow on.

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On 10/17/2018 at 8:52 AM, Foxster said:

 

To reduce drag to a level that will make the Onion useable you will need something like this (or a fairing)...

Let's be honest...the Onion, Pea and Pomegranate are useless apart from some historic recreation purposes. 

1) So basically the top node corresponde to another 1.8m tank? or just a 1.2m?

2) I resent the "useless" aspect, in that the KV-3 is a very compact way to stuff 3 kerbalnauts in tight space, which is helpful when one (ie. me) put a constrain as to what the maximum size a craft should be (I really dislike using the 3.75m for the dragon capsule, since 3.75m is used to represent 6 to 8m IRL tanks -- way bigger than Falcon/Dragon's diameter)

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The nice thing about the round pods are that they have a built-in heat shield and decoupler, which saves on a decent amount of weight. Two things to watch out for is that the 3-crew version weighs so much that a single mk16 parachute may not slow it down enough. In addition, the heat shield and heat resistance on the pod is weak, and probably won't survive re-entry from the Mun and beyond, depending on your re-entry difficulty.

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