Vernor Engines taking over for MonoProp Thruster Blocks

[WanderingKid]

So I've a question for some of the more nuanced players who swear by Vernor Engines over the RCS thruster blocks.  I personally typically use them as secondary controls during very heavy launches to keep things aimed where I want them, and after that I ignore them.

For those of you who typically only use Vernors, how do you place your engines for front/back translation during docking maneuvers?  Assuming your docking port isn't on your nose, as mine is typically strapped to the side somewhere, it's not simply a matter of using your engines as you need to brake in fine increments as you line up, so without some very unique attachments (like strapping some I-Beams on at awkward angles), I'm wondering how it's done?  Words are good, pictures would be awesome!  Thanks in advance.

[fourfa]

I'm a huge fan of hiding all RCS (and power... and cooling, and everything) in cargo bays. Like so:

https://kerbalx.com/fourfa/ORCA-v2

But I also always set up RCS to only fire in translation, and use reaction wheel modules (as many as needed) for attitude control. 

Edited March 31, 2017 by fourfa

[Cunjo Carl]

As an avid vernor aficionado, I can attest this is a constant problem. Generally, I get by with attaching them to any available surface such as adapters or literally any radial rigging. When doubt, if you're trying to vernor a dead cylinder like this Sr. docking + poodle fuel depot, you can make your own little hard points out of basic fins or radial decouplers. These can be placed anywhere, but for aesthetics I tend to put them near the base.

Because pictures were encouraged, here's some large but highly compressed jpgs to show the idea:

Spoiler

Where to put the vernors on this cylinder?

Make little hardpoints!

 

Tada! Won't break your deltaV budget (if used sparingly) or weird out your aero. The vernors reenter about as well as the standard fuel tanks will, but be forewarned the basic fins will always be the first thing to burn off! Structural D wings are a larger but much less meltable substitute for the little basic fins.

 

 

Good luck and have fun with one fewer resource to worry about, @WanderingKid!

 

Edit: Just discovered the little landing gear can be used to make a handsome little place-anywhere-5-way-rcs-port for vernors. It may weight half a ton, but look- It's so cute! (Steering the wheel doesn't move the vernors, sadly. Steering can be disabled to prevent it from looking silly however.)

 

Edit edit: Last time I swear! I keep thinking of new ideas 2 minutes after posting. This setup is probably the simplest solution... Two-way and four-way place-anywhere-rcs-blocks can be made using a cubic strut. Given how often I've faced this problem, how I never considered using a mini strut until now is anyone's guess. It's not the nicest looking of the options, but it sure was easy to make. A picture is enclosed:

Spoiler

 

Edited March 31, 2017 by Cunjo Carl
With luck I won't think of anything else...

[Hotaru]

I've taken to building vernor quads around the 0.625m nosecones and mounting four of them at 45 degree offset.

 

[Gordon Fecyk]

AeroGav has twice built craft capable of VTOL on Minmus using Vernors. It's cool to look at, though it's just as easy to build a craft that slows down vertically and then rotate horizontally, letting Minmus' gravity do the rest.

The Vernors only needing LFO to operate does mean one less fuel type to have to carry around. They also have 6 x the thrust of the Place Anywhere RCS thruster for 2.3 x the mass.

--

[AeroGav]

The up/down/left/right translation thrusters can just attach radially as normal around CoM.

Rotation duties are taken care of  with reaction wheels.

For backing up, if you have a nose cone, it's easy enough to just mount a pair with 2 way symmetry on the tapering section where they are at least partially pointing forwards.

For reverse, I find upper stage rocket bells are normally much smaller than the diameter of the engine base.  Whilst you're not allowed to radially attach to engines,  you can radially attach to the fuel tank just above the engine, then rotate 90degrees to have the thruster pair point "down".  Then offset the thrusters so they appear to be attached to the engine base plate - there's plenty of room either side of the engine nozzle.

In Kerbal space program, Vacuum engines have smaller nozzles than sea level engines   because they are less powerful right?  It's not like you'd want to expand the gases more in a vacuum or anything....

[Wanderfound]

I only use Vernors for low-g VTOL. Descend on the main engines, then flip horizontal and fire up the Vernors at the last moment.

They're generally much too overpowered for docking use; monoprop RCS works better for that. For control during launch...well, that's what gimbal and fins are for.

On a ship like the one in the picture, I'd have the Vernors set to an action group so I can deactivate them while docking.

 

Edited April 1, 2017 by Wanderfound

[AeroGav]

2 hours ago, Wanderfound said:

I only use Vernors for low-g VTOL. Descend on the main engines, then flip horizontal and fire up the Vernors at the last moment.

They're generally much too overpowered for docking use; monoprop RCS works better for that. For control during launch...well, that's what gimbal and fins are for.

On a ship like the one in the picture, I'd have the Vernors set to an action group so I can deactivate them while docking.

 

I prefer leaving a bit of horizontal speed on - what' the point in using fuel to cancel remaining velocity and then more fuel to arrest descent (70ms is still a significant fraction of orbital velocity on Minmus) when you can use the brakes?  This would have been easier with wider gear/less wheelbarrowing tendency though (nose leg longer than the others!)

[Wanderfound]

1 hour ago, AeroGav said:

nose leg longer than the others

I've actually taken to setting my nose gear a bit shorter than the main wheels lately, thanks to a few high-wing-incidence ships that wheelbarrowed on takeoff even though the gear were level. I try to set it so the wing AoA is close to zero while grounded.

[juanml82]

13 hours ago, Wanderfound said:

I only use Vernors for low-g VTOL. Descend on the main engines, then flip horizontal and fire up the Vernors at the last moment.

They're generally much too overpowered for docking use; monoprop RCS works better for that. For control during launch...well, that's what gimbal and fins are for.

On a ship like the one in the picture, I'd have the Vernors set to an action group so I can deactivate them while docking.

 

Basic question, but my high school physics classes were too long ago: the vernor has 12 kN of thrust, right? So, as a rule of a thumb, one vernor attached to a 1.2 ton ship would result in a TWR of 1 (actually, just a bit more, right?) at Kerbin Tylo because Kerbin has an atmosphere. And multiplying that by the destination's gravity (in Gs, so as percentage of Kerbin's gravity) I can (roughly) calculate the TWR manually and determine how many vernors I need, right?

[Wanderfound]

2 hours ago, juanml82 said:

determine how many vernors I need, right?

Or you could look at the TWR figures in RCS Build Aid and multiply according to the g's at the intended destination.

I usually just eyeball it. They aren't actually intended for flight, just for keeping the descent rate reasonable over the last few dozen metres.

[AeroGav]

36 minutes ago, Wanderfound said:

Or you could look at the TWR figures in RCS Build Aid and multiply according to the g's at the intended destination.

I usually just eyeball it. They aren't actually intended for flight, just for keeping the descent rate reasonable over the last few dozen metres.

Similarly for Duna, they only need to support half the weight of the craft at most, the wings can do the rest in the thin atmosphere and keep a survivable landing speed.  Provided it has a low landing speed to begin with ofc - but it's easy enough get a spaceplane landing at 30 m/s empty on Kerbin

[Wanderfound]

6 hours ago, AeroGav said:

Similarly for Duna, they only need to support half the weight of the craft at most, the wings can do the rest in the thin atmosphere and keep a survivable landing speed.  Provided it has a low landing speed to begin with ofc - but it's easy enough get a spaceplane landing at 30 m/s empty on Kerbin

My high-wing-loading planes tend to stall and fall out of the sky at about 300m/s on Duna. So, my standard landing approach tends to go like this:

Get as low as you can while keeping it at about Mach 1, then gradually shift the load from the wings to the Vernors as the plane begins to stall. Just before touchdown, flare hard while firing the Vernors, using them as retrorockets. Pop the drag chutes just as you touch down.

 I can't remember if I hit the chutes early on that landing or if that's a bounce, but the screenshot is from immediately after chute deployment. The yaw is because one chute opened a millisecond faster; easily compensated for with steering.

Note that the speed has gone from 280m/s at 75m altitude to 70m/s in only eight seconds.

It's a high-adrenalin landing method, but it works.

Edited April 2, 2017 by Wanderfound

[StrandedonEarth]

You don't need to do anything fancy. You can simply rotate them and they attach and work just fine. This screenshot is just for illustration purposes, I'll usually gizmo them together and in a little more.

I only use the 4-way thruster blocks on the lightest craft where Vernors are way overpowered. Then I don't have to worry about the monoprop supply. Even on mid-weight craft CapsLock can be used to reduce thrust on the Vernors if they're too powerful.

Edited April 2, 2017 by StrandedonEarth

[Urses]

On 1.4.2017 at 4:31 PM, juanml82 said:

Basic question, but my high school physics classes were too long ago: the vernor has 12 kN of thrust, right? So, as a rule of a thumb, one vernor attached to a 1.2 ton ship would result in a TWR of 1 (actually, just a bit more, right?) at Kerbin Tylo because Kerbin has an atmosphere. And multiplying that by the destination's gravity (in Gs, so as percentage of Kerbin's gravity) I can (roughly) calculate the TWR manually and determine how many vernors I need, right?

As rule of tumb it works pretty well for me too.

@topic  i use Vernons for Translation only on very big payloads/Ships. Monoprop is very Handy if you will dock "around corner", and if you will translate some xk-tones Vernones then.

Like @Cunjo Carl mentioned i build me some subassemblies with cubic in X, T and L Shapes. And i need only to adjast the cubic on CoM and have my freedom. For small crafts Vernons are a good substitute for main engine.

Funny Kabooms 

Urses