Laythe water landings?

[strider3]

I am trying to make a science gathering ship for the Jool system but, Laythe is making it hard. I'm wondering if this thing will float? Are the inflatable heat shields re-useable (like parachutes) with an engineer on board? Will this contraption even work to get to different water biomes on Laythe? It doesn't look very stable.

I have a feeling this is an exercise in futility and I will have to build 2 landers for Laythe exploration...one for dry land and one for water. I have absolutely no idea how to go about the water thing, however. How do you get a "boat" to all the far-flung Laythe water areas? Is it possible to build a boat that can take off of the water, enter an orbit for refuel and science transfer, then re-land elsewhere?

This one is going to be interesting!

Edited February 2, 2019 by strider3

[TheFlyingKerman]

How about a seaplane?

[bewing]

45 minutes ago, Victor3 said:

I am trying to make a science gathering ship for the Jool system but, Laythe is making it hard. I'm wondering if this thing will float?

Almost all KSP parts float, with very rare exceptions. Of course it will float.

45 minutes ago, Victor3 said:

Are the inflatable heat shields re-useable (like parachutes) with an engineer on board?

Nope.

45 minutes ago, Victor3 said:

Will this contraption even work to get to different water biomes on Laythe? It doesn't look very stable.

It doesn't look like it'll have enough dV to be able to make more than one hop. So maybe 3 water biomes, tops.

45 minutes ago, Victor3 said:

I have a feeling this is an exercise in futility and I will have to build 2 landers for Laythe exploration...one for dry land and one for water. I have absolutely no idea how to go about the water thing, however. How do you get a "boat" to all the far-flung Laythe water areas? Is it possible to build a boat that can take off of the water, enter an orbit for refuel and science transfer, then re-land elsewhere?

This one is going to be interesting!

Yup, building a Laythe seaplane SSTO is pretty easy, actually. One of them can easily hit every biome on Laythe -- land and water.

[strider3]

Then I will look at building a seaplane SSTO for Laythe exploration. I will probably keep the lander, above, for the other Jool moons and as the repository for all science gathered in the Jool system. This should be fun! A new ship construction challenge!

Edited February 2, 2019 by strider3

[bewing]

A few tips then: you need canards on the front end of your plane, because you need positive lift to get out of the water. Trailing edge elevons are worthless for water takeoffs.

You also need to have the canards below the surface of the water (and therefore below the midline of the plane). This also helps to lift the nose out of the water -- which gets you up to takeoff speed.

If you have a Rapier engine, that would probably be your best bet. Other engine options would probably be a Whiplash/terrier combo, Whiplash/spark, panther/spark, or whiplash/nuke, I think.

 

Edited February 2, 2019 by bewing

[Aeroboi]

9 hours ago, bewing said:

A few tips then: you need canards on the front end of your plane, because you need positive lift to get out of the water. Trailing edge elevons are worthless for water takeoffs.

 

That depends.

Most water planes have trailing edge control surfaces like the Cessna 182. If you put wing incidence on your wings (Which I Would do anyway) the plane will takeoff without pitching.

In KSP the problem is that the CoM and dry mass tends to be further to the back then in real aircraft where the tail is a light construction work without fuel in it where in KSP it is usually a fuel tank plus a engine at the back. For that purpose you need a longer floater that extends further to the back then in i.e. a real seaplane to balance the floating point because of weight distribution, for that purpose it will be more difficult to pitch out of the water.

In KSP all you have to do is workaround those weight problems by re-balancing engines and fuel accordingly. For efficiency I would put wing incidence on the wings and just make sure that the seaplane SSTO can gather enough speed to climb out from the water horizontally. Also make sure that the trailing edge control surfaces are furthest to the back so there's is maximum pitching moment.

Edited February 2, 2019 by Aeroboi

[PunkyFickle]

On 2/2/2019 at 4:18 AM, Victor3 said:

Is it possible to build a boat that can take off of the water, enter an orbit for refuel and science transfer, then re-land elsewhere?

A seaplane is most likely your safest bet indeed. As for knowing wether it will float on Laythe, the simplest thing you can do is to test in on Kerbin. After all, its oceans and atmosphere are very similar to what you get on Laythe (and the hydrostatic doesn't vary from one planet to another in the game, as far as I know). About going back to orbit and reentering between each and every biome (if that is your plan), that sounds extremely inefficient. Remember about the science storage and the fact that scientists can reset experiments.

[bamslamkabam]

No komrade, inflatable heat shields are one time use. The best way is a spaceplane and a separate ascent system. But still the gravity is considerably weaker than kerbins and the atmosphere is 50 km. Plus the SOI is pretty easy to escape since the strong jool gravity well will dominate the space.

[AeroGav]

Developing a seaplane is tricky however.  People often struggle making airplanes, because the game doesn't show them the info they need to see (drag values, static stability plots, thrust curves) unless they install mods.         For seaplanes , its even worse.   Water drag is not reported anywhere, nor hydrodynamic lift.      I think a hydrofoil approach is more elegant than using floats,   but the results can vary a lot.         I recommend making the seaplane first, then look at modding it for SSTO,  then use cheat menu to test it will land on Laythe without damage and unstick again,   then think about flying your mission.

I've heard that Laythe is slightly harder to seaplane from, because the air density at sea level is like 6km up on Kerbin.   Gravity is less,  but water drag is not.

On the other hand, Laythe is much easier to get to orbit from than the surface of Kerbin.     I'd make sure it can get off the water in Laythe and then reach orbit,  even if that means it needs drop tanks or booster engines to make orbit on Kerbin.

You probably want lots of wing area (hydrofoil lift, and to reduce takeoff/landing speed) and most or all your jet engines will be Panthers,  since these have the highest TWR on takeoff conditions.   Panthers max out at 800 m/s or so,   but from that point getting to laythe orbit is super easy.

You could probably try adapting this craft of mine if you like,  maybe replace that wheesley with a panther, give it slightly stronger gear and an inline clamp o tron?

https://kerbalx.com/AeroGav/Puffin

[AeroGav]

Well,  I started designing a new airplane for this job,   and predictably enough i'm running into issues "unsticking" from the water.   I think i got lucky with the "puffin" pictured in my previous post.

I gave the wings sharp dihedral and had them extend below the fuselage at the centreline,   so the innermost/lowest parts of the wing dip in the water and act as hydrofoils.

Problem is,  when you try to pitch up ,  the front parts of the wing come out of the water,  so the centre of hydrodynamic lift goes well to the rear.   That is to say, it really does not want to pitch up at all,  and the faster it is going, and the higher the airplane rises out of the water,  the worse this gets.  Also when you do manage to generate some pitch angle,  the rear fuselage dips into the water slowing you down.  I eventually got it to unstick at 90m/s (twice the speed it lands at, with full tanks) and then it goes into a  vertical climb.

So,  guess i need to start again.     attempt 2.0 will have flat wings,   and i'll make separate hydrofoils that extend well below the fuselage,  i'll have to make the front ones have tall "legs" so they stay in the water when the airplane is pitched up.        The problem with this, is that it's surely going to mean no ground clearance ,  or almost no ground clearance when land based.   Perhaps i should just remove the landing gear completely and have it launch from the runway on a dolly,   after that it will only ever see air, space , or water.

 

[farmerben]

I tested loads of seaplanes while working on my jool5 mission.  This particular model has a water takeoff speed of 44 m/s.

The front wing has slightly higher AOA than the back one.  Hydrodynamic effects actually make this plane pitch down, but it nevertheless will lift off from water with no controls at around 100m/s.  

Note: docking ports have pretty bad aerodynamic drag, but swapping them for nose cones doesn't noticeably change its water takeoff performance.  The design shown has no trouble taking off from water and reaching orbit on Kerbin or Laythe.  The concept is to use it as a Jool 5 mothership, swap the rapiers for nukes in orbit of Laythe for the return trip, and land it on Kerbin as a glider.  Those parts of the mission all worked.  The Tylo landing, and the return to Kerbin are the hard parts.  I've got quite a few seaplanes that are lighter and sleeker than this which can get water takeoff speeds close to 50 m/s, but none is quite as good as this.  

 

 

Edited February 8, 2019 by farmerben