Horizontal Landers

[Halfdan]

hello fellow kerbonauts!

i was wondering if there are any designs for horizontal landers floating out there?

or at least tips for constructing one using stock parts, i tried, but the downward facing enginges allways flipped the craft over and rammed it into the ground

[Majorjim!]

I've made a few, my best remains hidden for now, part of my upcoming constellation pack rebuild. Just make sure the COM and COT line up. Also that fuel drains in a manner that does not cause those two things to deviate from one another. 

[Superfluous J]

Are you talking planes? Do a search for "VTOL" there are hundreds of tutorials out there and dozens of good ones

[Tex_NL]

How do you keep a VTOL stable?

Practice, practice, practice! (In both flight and design.)

Edited November 27, 2016 by Tex_NL

[MaxxQ]

32 minutes ago, Tex_NL said:

How do you keep a VTOL stable?

Practice, practice, practice! (In both flight and design.)

Or, if you don't mind mods, there's Throttle Controlled Avionics:

 

[LordKael]

I use camber for the engines to increase stability. 

[OrbitalBuzzsaw]

39 minutes ago, LordKael said:

I use camber for the engines to increase stability. 

Wut?

[Tex_NL]

3 minutes ago, OrbitalBuzzsaw said:

Wut?

What is camber? You'll find all about it right here!

Edited November 27, 2016 by Tex_NL

[Vanamonde]

This exchange of spacecraft (for such it will turn out to be) has been moved to Spacecraft Exchange. 

[LordKael]

2 hours ago, OrbitalBuzzsaw said:

Wut?

I tilt the engines on the VTOL system outwards, so that they are pointed approx 30degrees off vertical, and that adds immeasurable stability to the vehicle on landing, particularly on high thrust maneuvers. 

[Cupcake...]

6 minutes ago, LordKael said:

I tilt the engines on the VTOL system outwards, so that they are pointed approx 30degrees off vertical, and that adds immeasurable stability to the vehicle on landing, particularly on high thrust maneuvers. 

I hate to break this to you but angling the engines anything but straight down is just wasting fuel and does nothing for stability.

 

Cupcake...

Edited November 27, 2016 by Cupcake...

[LordKael]

21 hours ago, Cupcake... said:

I hate to break this to you but angling the engines anything but straight down is just wasting fuel and does nothing for stability.

 

Cupcake...

I don't know whether to be flattered that KSP's Lander/Dropship expert quoted me, or upset that I was wrong...

 

Is it a quirk of the game mechanics that your statement is true, or real physics as well? 

[Frank_G]

Here my latest Konstellation lander (stock). It can be downloaded from the Duna Trek thread (link in my sig).

And a few older designs, i did during the early days:

Tylo Lander (stock):

Konstellation Type II (stock) - is available on my craftfile thread:

Duna Lander (modded):

 

[sdj64]

When building a VTOL that also has horizontal engines, set the horizontal engines' thrust to zero in the VAB then use the Center of Thrust indicator to position your vertical engines.  Try to make your COM move as little as possible from full to empty.

One way I have done it for large ships even if the COM moves is to have most of the VTOL engines slightly back of COM and then have one engine off center as far towards the front as possible, use the thrust limiter on that to stay level. The mothership in the picture uses this technique.  For smaller landers it can be easier to build symmetrically.  The weight of the cockpit of the small lander in the picture is offset by a Science Jr and a scanner on the back end, and reaction wheels are enough for the minimal shift in COM.  It also has only one fuel tank, which helps keep the COM steady (this was much more important before 1.2).

 

20 minutes ago, LordKael said:

I don't know whether to be flattered that KSP's Lander/Dropship expert quoted me, or upset that I was wrong...

Is it a quirk of the game mechanics that your statement is true, or real physics as well? 

This should apply to real physics too.  For example most quadcopters don't have cambered rotors.  The only reason I can think of to angle them like that is so that if you're carrying a wide cargo underneath, the exhaust can clear it to the sides.  As an example the Curiosity skycrane's thrusters cambered outwards to avoid hitting the rover with exhaust.

You might be confusing it with car wheels, which are sometimes cambered outwards because of the lateral forces on the wheel in a turn.  Air vehicles don't have to worry about that.

[Cupcake...]

4 hours ago, LordKael said:

I don't know whether to be flattered that KSP's Lander/Dropship expert quoted me, or upset that I was wrong...

 

Is it a quirk of the game mechanics that your statement is true, or real physics as well? 

Don't be upset, it's a common misconception. As @sdj64 pointed out the only reason to angle nozzles is to avoid damaging a payload through the engine wash, other then that straight down is the way to go, case in point:

As you can see there's a slight angle but this is probably just to help keep the hot exhaust away from the pilots legs.

 

Cupcake...

Edited November 29, 2016 by Cupcake...

[LordKael]

1 hour ago, Cupcake... said:

Don't be upset, it's a common misconception. As @sdj64 pointed out the only reason to angle nozzles is to avoid damaging a payload through the engine wash, other then that straight down is the way to go, case in point:

Many months ago, I saw a video in which a quad thrusted VTOL type lander flared all four engines out to 45 to kill horizontal velocity, and used the same function to hold a hover. I suppose I assumed the flare was to increase stability. Guess this is what I get for getting my physics from movies.

[Rune]

Yup, the only really important bit is that you have to have your CoT (Center of Thrust, the result of adding all the thrust vectors on your ship) going exactly through your CoM (Center of Mass), or you will be creating some torque that you will have to counteract. The key for this is fuel flow, because it will change the mass distribution of your ship, or in other words move the CoM.

A good trick is to arrange the fuel tanks in a symmetrical fashion around the CoM. This can be easily seen in @Cupcake...'s designs (the are very symmetrical in a lot of axises), but really, as long as the fuel drains symmetrically, you will be fine. Notice how I'm balancing the weight of the cockpit here, all the way in the front, with the engines slightly to the back, and I leave the variable-mass cargo bay smack in the center of the bird, arranging fuel tanks with identical capacities around it, front-back (Mk3 LFO) and side to side (the wings, for LF):

That means that no matter the fuel and/or cargo situation, the CoM stays in the same place, and the thrust torque is always zero, or as close to it as KER and the UI will let me go. It also does wonders for the aerodynamics, because you can place the CoL very, very close to the CoM without it going in front of it at any time, decreasing the amount of control authority you need. Here, a much simpler design form long ago, still attached to its upper stage:

 

Rune. It sounds fancy explained like that, but once you get the principle, it's rather simple, like levers. The CoM is the pivot, and you have to balance things out.

Edited November 29, 2016 by Rune

[cosimas]

One trick I've found is to slap a docking port or probecore on top at the CoM, and control from there - this makes the navball a whole lot easier to read and use for gentle landings.

[SchweinAero]

On 28.11.2016 at 0:45 AM, LordKael said:

I tilt the engines on the VTOL system outwards, so that they are pointed approx 30degrees off vertical, and that adds immeasurable stability to the vehicle on landing, particularly on high thrust maneuvers. 

 

23 hours ago, sdj64 said:

This should apply to real physics too.  For example most quadcopters don't have cambered rotors.  The only reason I can think of to angle them like that is so that if you're carrying a wide cargo underneath, the exhaust can clear it to the sides.  As an example the Curiosity skycrane's thrusters cambered outwards to avoid hitting the rover with exhaust.

You might be confusing it with car wheels, which are sometimes cambered outwards because of the lateral forces on the wheel in a turn.  Air vehicles don't have to worry about that.

While angling engines outwards is never really beneficial in reality or in current KSP, there once was a use for the method. In the times when jets used to flame out much more unpredictably, you could have two or more engines next to one another, each one still applying thrust exactly on the CoM. You lost some of the thrust, but gained a ship that wouldn't spin wildly after an asymmetric flameout.

@MeticulousMitch in particular made some interesting vessels using this technique and called it "StaboJet".

 

[Azimech]

Here's my dropship, the 77I- SRLR Zanna. It contains the Lowell Rosalie, a 6 seat long range science rover; and a laboratory. Can land anywhere, cannot reach orbit from Eve, Kerbin, Laythe and Tylo. Dropship & rover combined is a mere 180 parts.

You can find it here: https://kerbalx.com/Azimech/77I--Lowell-Rosalie