What a difference a engine can make (SNEAKY)

[Korizan]

So I was going back and testing some old rockets to answer a thread and I realized something critical that most likely gets overlooked and more important a HUGE difference from the BETA 0.90 (mind you a good difference)

The Rocket top to bottom (this rocket will get you into orbit)

MK16 / MK1 + (MechJeb 2 Module) / Heat Shield / TR-18A / FL-T200 / LV-909 / TR-18A / FL-T800 / FL-T800 / MAIN ENGINE

You can replace the (2) FL-T800's with (4) FL-T400's or (8) FL-T200's with the same result.

[Notice it has NO fins]

The Main engine is the fun part.

I had a LV-T45 "swivel" (THIS ENGINE CAN GIMBAL) for a main engine and it flew into orbit just fine.

For fun I replaced the LV-T45 with a LV-T30 (it has more power right but it CAN NOT GIMBAL )

Well that is where it got interesting the rocket did a flip @ 6500m and was just uncontrollable.

Placed (4) Basic Fins at the bottom of the Rocket and it was stable enough to fly into orbit but the fuel efficiency was terrible.

A tiny change for more realism (a good thing) that is most likely driving some players up the wall when they first start out.

What makes things worse is there are several good tutorials out there for 0.90 on how to get into orbit but they used the LV-T30 which worked just fine back then.

However now it is the engine of doom without fins.

Makes me wonder what other tiny little items where put in that are driving people insane.

Edited May 19, 2015 by Korizan
Added in options for first stage

[TothAval]

i have put fins on every rocket for a long time now, mostly because of the better maneuverability in the denser part of the atmosphere. i never use the LV-T30. i had some minor problems getting into orbit when 1.0 came out, but they didn't last, i personally don't consider it more or less difficult to launch rockets, just the same matter of trial and error as before

good observation, hopefully this will help those people which are still having trouble getting to orbit.

[Caelib]

With regard to rockets, I feel like fins are just a band-aid for non-efficient aerodynamic craft design.

If your rocket is flipping, you're probably going too fast and/or trying to put too much payload into orbit with not enough rocket.

[Sky_walker]

With regard to rockets, I feel like fins are just a band-aid for non-efficient aerodynamic craft design.

Also doing too aggressive maneuvers while still in the atmosphere. If you still have a problem despite of being very careful - sometimes it might just be better to push above 15km with SAS on before touching controls. Yea, you'll waste some Dv, but also save a lot of time.

[Captain Sierra]

With regard to rockets, I feel like fins are just a band-aid for non-efficient aerodynamic craft design.

If your rocket is flipping, you're probably going too fast and/or trying to put too much payload into orbit with not enough rocket.

In 1.0, things were WAY too hot and not draggy enough. The 1.0.1 changes knocked that heat down but boosted up the drag a bit too much. Doing some stalking of Maxmaps on twitter and reading a few other things, either a 1.0.3 hotfix is coming or in 1.1, there are going to be a few tweaks. Drag is coming down a wee bit and heating is going up some (aerobraking return from Duna will require a heat shield)

Fins are a bit of a bandaid for the current atmosphere being a bit more flip-happy than the community as a whole is happy with (this is a pretty divisive issue, but if Squad is turning back the drag just a hair, then the community opinion overall must be its a bit too flippy).

[mikegarrison]

With regard to rockets, I feel like fins are just a band-aid for non-efficient aerodynamic craft design.

If your rocket is flipping, you're probably going too fast and/or trying to put too much payload into orbit with not enough rocket.

In career mode, you start out with only non-gimballing engines. Fins are very useful for aerodynamic stability (as the OP points out). Later, when you have gimballing engines, they are less useful.

[Korizan]

I am not how I feel about fins.

Fins do help you stabilize even a stable rocket, lets face it in RL you won't be flying a rocket into space manually.

There is also the consideration of keyboard versus joystick.

Keyboard controls are either on or off where a joystick gives you degrees of control and that can make a huge difference when trying to control a rocket on assent.

Personally I use Mechjeb simply because it may be fun at times to get off the ground manually I generally have other things in mind like fuel to get to another planet and I am happy to let the computer run the assent.

But this may be the grind.

For those that use mechjeb then changing in the atmosphere means tweaking the assent profile.

Where if you are flying manually it may become ridiculously hard to get into space.

So what does the squad do.

Make it very realistic and put a mechjeb style autopilot into the game or make it less realistic and easier to fly on manual. ?

Edited May 19, 2015 by Korizan

[spacenut1337]

I think locking the first gimbaling engine behind an upgrade and the addition of tier 0 fins introduces players to a key concept - drag can work in your favor to keep things pointed where you want them.

What I find frustrating is the tendency for SAS oscillations to diverge instead of converge. The system just loves to overcorrect.

[Fleb]

LVT30 is better as a low atmos booster, it's better than solids. The LVT45 has the now all important gimbal and better ISP, so I use it on my core stages.

[mikegarrison]

I think locking the first gimbaling engine behind an upgrade and the addition of tier 0 fins introduces players to a key concept - drag can work in your favor to keep things pointed where you want them.

What I find frustrating is the tendency for SAS oscillations to diverge instead of converge. The system just loves to overcorrect.

That's because the stock rockets are too flexible. The cockpit gives the input to the rocket to steer north, let's say, so the engine steers north. But by the time the cockpit finally points north, the engine has oversteered. So the cockpit tells the engine to steer south. Etc. If the SAS controller was more rigidly connected to the place where it is steering from, this wouldn't be a problem.

[Guest]

If you're going to use solid rocket boosters, then fins with control surfaces are extremely useful in your initial boost phase. If you do things properly, and don't overbuild your rocket, you can get into orbit easily in a few minutes. When I first started playing KSP, getting a spacecraft into orbit seemed like an unbeatable challenge. After flying a rocket into orbit a few thousand times now it's a piece of cake, and I barely have to think about it even when I screw up.

Here is the final build of my "Project Moho" Rocket, it's only purpose is to put a science package into LKO.

Spacecraft:

Clamp-O-Tron Jr.

MK1 Command Pod

(2) MK2R Radial Parachutes

1.25m Service Bay with: 2 Z200 Batteries, 4 OX Stat solar panels, 2 Thermometers, 2 Barometers, and 2 Goo Canisters

1.25m Heat Shield

Decoupler

Service Module:

(4) RCS Thruster Blocks

Science Jr.

FLT 200 Fuel Tank

LV909 Engine

Decoupler

Sustainer Stage:

(2) FLT - 800 Fuel Tanks

FLT - 400 Fuel Tank with (4) AV-R8 Winglets

LV T45 Engine

Booster Stage:

(2) Aerodynamic Nosecones

(2) Rockomax BACC SRB @ 77% thrust

(2) TT-38K Radial Decoupler

The total cost of the rocket is less than 30,000 spacebucks and it can reach a 250km x 250km orbit while still returning to Kerbin with the fuel onboard.

(Ignore the video thumbnail, it's just an old screenshot.)

Edited May 19, 2015 by Guest

[Archgeek]

That's because the stock rockets are too flexible. The cockpit gives the input to the rocket to steer north, let's say, so the engine steers north. But by the time the cockpit finally points north, the engine has oversteered. So the cockpit tells the engine to steer south. Etc. If the SAS controller was more rigidly connected to the place where it is steering from, this wouldn't be a problem.

It's also rocket gimbals being all-or-nothing. I did a mun injection for a re-entry test, lazily hitting hold prograde on an OCTO-2, and stared bemused at the remainder of my LV-T45 lift stage flipping out in each available direction for a second before it emptied.