Vernor Lander Leg

[Fwiffo]

EDIT: Here's my "VernorLeg" part if anyone wants to try it out: http://tinyurl.com/VernorLeg

Anyone else notice the Vernor engine seems to fit "just right" onto the mounting bracket of an LT-2 Landing Strut?  When the legs are extended there's plenty of clearance for the thrust exhaust.  And when the leg cylinder retracts, it fits reasonably snug into the round "pocket" formed by the curved front face of the Vernor.  Was that intentional?

Doesn't this just cry out for a UbioZur weldment?  I did a proof of concept (with some manual editing) and I didn't see any immediate problems welding together a thruster and a leg.  Both seemed to work as expected.  But I'm concerned that as the legs take on "wheel damage" my thrusters won't point the right way anymore.  I've noticed the mounting bracket on the leg can sort of twist / wobble from the surface it's mounted to, and the deflectionMagnitude stuff in ModuleWheelDamage makes me nervous.

Edited August 31, 2016 by Fwiffo
Add link to VernorLeg part

[LordFerret]

29 minutes ago, Fwiffo said:

Doesn't this just cry out for a UbioZur weldment?

UbioZur has not yet been updated for v1.1.3, and using the current version is unreliable. But, yea.

[Rocket In My Pocket]

Great find!

I'm definitely gonna use this design on a future lander.

[samstarman5]

Well, anything is a hazard once you take the craft out of the VAB or SPH. With an experienced engineer along, you can fix wheel damage.  Are you wondering if the thruster ends up out of alignment because of that damage, that it won't return back to nominal position when the leg is fixed?  Sounds like an excuse to have Bill take the craft out for a shakedown.

That is a rather sweet way that those two do fit together. I will definitely keep it in mind for my future builds.

[W. Kerman]

Cool, gonna have to try this out!

[Kyrt Malthorn]

Not too derail the topic too much, but...   why do you use vernors?  Regular monoprop RCS get better ISP and while yes, most craft designs usually carry much more LF/O, I find I rarely need more RCS than lander cans already store - no extra tank mass needed...

Edited August 14, 2016 by Kyrt Malthorn

[EpicSpaceTroll139]

Monopropellant (quads and linear)

ISP in vacuum: 240 

Thrust: 1-2

Bipropellant (vernor)

ISP in vacuum: 260

Thrust: 12

The thrust and ISP on the vernor is better.

I don't usually use them on landers, but then I don't usually build large landers. I can easily see them being useful on medium to large size landers. I typically use them on space shuttles for their stabilizing power during reentry. Their use of LFOX means that I can use them a lot without needing a separate fuel source, which is nice, if not completely necessary.

Edited August 14, 2016 by EpicSpaceTroll139

[Guest]

I often slot lights into places like this.

[Fwiffo]

13 hours ago, samstarman5 said:

Are you wondering if the thruster ends up out of alignment because of that damage, that it won't return back to nominal position when the leg is fixed?  Sounds like an excuse to have Bill take the craft out for a shakedown.

Sort of.  I assume if it breaks outright, it will return to the correct position once fixed.  My concern is if the legs "wobble" out of position, but not enough to break.  In this case the Vernors may be in slightly wrong directions.  I assume the game will compensate to a degree by adjusting their thrust, but I'd no longer be getting as efficient performance (since the off-axis thrust components will cancel each other out).  So I guess my question is really:  If lander legs wobble or become misaligned due to minor bumps and scrapes, do they spring back to their original position once the craft is off the ground?

Edited August 15, 2016 by Fwiffo

[magnemoe]

10 hours ago, Kyrt Malthorn said:

Not too derail the topic too much, but...   why do you use vernors?  Regular monoprop RCS get better ISP and while yes, most craft designs usually carry much more LF/O, I find I rarely need more RCS than lander cans already store - no extra tank mass needed...

yes I use vernors on two ships types, one is the huge orion pulse nuclear who is huge, long and have an heavy engine I can not mount them on. Second is an tanker with 3 long MK3 tanks who needs to land accurate at Minmus base.

I have put RCS clusters inside legs a few times but thought it dangerous so I eiter put them above or below,

[The Optimist]

Vernors are fantastic for large craft, while the ordinary RCS thrusters are good for docking.

[Fwiffo]

So I turned this concept into an actual part, and added a link to it in the original post.  Feel free to give it a whirl, and let me know what you think (especially if you wind up doing any testing in relation to broken lander legs).  No promises on whether it will be maintained.

It's intended for use it on a self-refueling, scientific biome hopper I'm working on which will have an aggressively reduced part count via weldments.  Will post more on that at a later date.

Edited August 31, 2016 by Fwiffo

[Sharpy]

On 15.08.2016 at 1:13 AM, Kyrt Malthorn said:

Not too derail the topic too much, but...   why do you use vernors?  Regular monoprop RCS get better ISP and while yes, most craft designs usually carry much more LF/O, I find I rarely need more RCS than lander cans already store - no extra tank mass needed...

I, on the other hand, often run out of RCS fuel. It depends on the rocket. If tiny landers are your thing, sure. But if you create a fully-fledged biome-jumper base, which needs to be set horizontally to activate ISRU and set back upright for launch, you need more grunt. (but then of course landing legs will be a very poor choice, unless you plan the base to move to different biomes over the surface, without use of engines...)

[Xyphos]

that's pretty neat. often I stick an anywhere RCS port in the middle of the RAPIER engines, it just seems like a good spot to put em.

[Fwiffo]

Thanks.  I like to make crafts that maintain a static CoM (achieved by using only one LFO tank, centered at the craft's CoM; or situating expendable resources such that they balance each other out as they're consumed), then stick on a single set of Vernors precisely lined up with that CoM.  Gives you perfect translation control throughout your entire flight profile, with zero unwanted torque.  So I expect these legs will really shine when you can line up their Vernors with the craft's CoM.

Edited August 31, 2016 by Fwiffo

[Daveroski]

The thrust from the engine hitting the retracted leg should damage the leg or at best greatly reduce the overall thrust but hey... never let a silly thing like physics stop you from doing what feels right eh?

 

[Fwiffo]

13 minutes ago, Daveroski said:

The thrust from the engine hitting the retracted leg should damage the leg or at best greatly reduce the overall thrust but hey... never let a silly thing like physics stop you from doing what feels right eh?

Hey, c'mon, I'm sure Wernher von Kerman baked idiot-proofing into these things so that if some moron decides to fire thrusters while the legs are still retracted, the high velocity exhaust will knock the legs down and safely out of the way.  Right?  (I'm looking at you, Jeb...)

(...in fact I did briefly consider attempting to mod this part to disable the Vernors when the legs are retracted, or auto-extend legs when you hit the thrusters)

Edited August 31, 2016 by Fwiffo

[Daveroski]

Physics aside, the problem I would see with this is that the engines and legs both have to be mounted very precisely to allow the engines to fire against the COM.

Personally I prefer my COM to be below the root of the landing gear to help prevent a lander from falling over on an incline.

In such cases the thrusters would produce unwanted rotation.