Boat Momentum Efficiency Challenge

[The_Rocketeer]

Let me put it like this - I have a boat. It is moderately large, it is made of a healthy number of parts, and it is very fast. If this is a challenge where speed and mass are the primary scorers I'll probably do respectably, but if it's a challenge where I'll be penalised for not designing a bespoke boat that only uses a fifth the number of parts to me that's a bit of a turnoff.

Just now, Ezriilc said:

Honestly, I think it needs to be simpler.  If I need to throttle down during my run, then I should be able to.  The total elapsed time, and total fuel used, is all that should matter.

In an efficiency challenge, it would be. As I said, confused challenge.

[seanth]

Some example scores using (mass*speed)/(parts*fuel per second):

Unnamed: (114tonne *97.4m/s)/(4parts*165L/s) = 16.82

I guessed at fuel usage before engine shutdown. 13329L/81sec

WYM: (35tonne*44m/s)/(80parts*0.86L/s)=22.38

Sure, WYM would beat that rocket monster, but honestly I sort of hope it would with it's fuel nomming

[Ezriilc]

But the L/s can be easily cheated or just different because I may not stay full throttle the whole way.  Trying to track or assume it through the entire run seems inaccurate.

[seanth]

8 minutes ago, The_Rocketeer said:

I see the issue with momentum - build a behemoth and move it, you win - but fuel efficiency has nothing to do with momentum. This challenge still seems very confused about what it is supposed to be.

Oh I dunno. Efficient movement of something heavy, and doing it fast seems like a noble goal. Thus "Momentum Efficiency"

But I'm totally willing to end this if the consensus is it should just be an efficiency challenge.

So let's burn this one and have an efficiency challenge. Furthest fastest without refueling?

Edited July 11, 2016 by seanth

[Ezriilc]

6 minutes ago, seanth said:

Oh I dunno. Efficient movement of something heavy, and doing it fast seems like a noble goal. Thus "Momentum Efficiency"

But I'm totally willing to end this if the consensus is it should just be an efficiency challenge.

 

I feel like efficiency means we should move something other than just the craft and its fuel.  Like some cargo or kerbs.

[seanth]

8 minutes ago, Ezriilc said:

I feel like efficiency means we should move something other than just the craft and its fuel.  Like some cargo or kerbs.

We could require the inclusion of a cargo bay (though it doesn't necessarily need anything in it.

I'm indifferent on this point, though it would possibly disqualify craft people already have made and want to show off.

Edited July 11, 2016 by seanth

[Ezriilc]

Upon further consideration, I've decided that I'm happy with whatever rules you want to set.  It's your challenge, and I'm totally gonna win anyway. 

Perhaps include a number of kerbs in the score formula.  Such as (at the target destination) kerbs/time/fuel used.  But again, this was just an idea and I'm cool with whatever you choose.

[The_Rocketeer]

15 minutes ago, Ezriilc said:

Upon further consideration, I've decided that I'm happy with whatever rules you want to set.  It's your challenge, and I'm totally gonna win anyway. 

This.

I agree with u on moving something heavy efficiently, but the reason your previous challenge failed is that it's much easier to move something very massive a little bit than it is to move something very small very fast simply because of the physics of drag. So while mathematically/in vacuum there's no difference between 1kg at 100m/s and 100kg at 1m/s, in reality/on Kerbin there is because the difference in loss to drag is way way higher at 100m/s than at 1m/s.

10 hours ago, seanth said:

Efficient movement of something heavy, and doing it fast seems like a noble goal. Thus "Momentum Efficiency"

 

10 hours ago, Ezriilc said:

I feel like efficiency means we should move something other than just the craft and its fuel.  Like some cargo or kerbs.

This is the answer to the behemoth problem:

Specify a payload, say a Jumbo-64 tank and see who can build a boat that gets that payload to the highest speed for the lowest fuel consumption.

Then effectively you're not measuring or scoring the momentum of the whole craft, you're just measuring the momentum of the payload.

[Ezriilc]

Let's do this!  @seanth gimme some rules to kill ya'all with.

[SpannerMonkey(smce)]

Hi, in all the years playing KSP i've never done a challenge before. Soooooooo hydrofoil;s aren't mentioned not mentioned in the rules , therefore I tentatively enter my challenge cat,  with a score of 56.36037     mass 17.576 speed 144.3  parts 45

It goes a lot faster and does actually take off around 190ms which may be an issue, because then its a god awful aircraft

 

[Ezriilc]

I think the rules for this challenge are still up in the air until we get the final word from @seanth.  But, you're on the right track!

Interesting ship - I like it.  Can we get a copy of your .craft file?

I've got my entry ready, but I'm waiting for the rules to solidify before unveiling her.  She's gonna have some big numbers for sure.

[seanth]

Just now, Ezriilc said:

I think the rules for this challenge are still up in the air until we get the final word from @seanth.  But, you're on the right track!

Interesting ship - I like it.  Can we get a copy of your .craft file?

I've got my entry ready, but I'm waiting for the rules to solidify before unveiling her.  She's gonna have some big numbers for sure.

Sorry for the radio silence. I've been at work, and I wanted to re-read something that inspired the contest in the first place: "What Price Speed?" by G. Gabrielli and T. von Karman. Yes, that Karman. Part of his interests had to do with efficient movement of things...especially big things like planes and rockets.

Hold tight. Nearly done testing, making sure the scoring makes sense.

Somewhat related, I am totally up for a long distance+no refueling boat competition, too. (different challenge of course)

[Ezriilc]

1 minute ago, seanth said:

Somewhat related, I am totally up for a long distance+no refueling boat competition, too. (different challenge of course)

This.

[seanth]

Ok. Looks like it's going to be (current Thrust*current velocity)/units fuel per sec (which is (momentum*acceleration)/fuel per sec

Just momentum/fuel ended up with interesting (and realistic) situations where if a very heavy boat travelled very slowly, it would get a great score.

Hopefully this calculation method will be a good intersection between realistic boat efficiency and fun (i.e. going fast-ish)

 

Updating the rules and my first entry to show how to easily get the values now.

 

 

[seanth]

Ok. Revised rules up, and my first submission walks people through the score.

2 hours ago, SpannerMonkey(smce) said:

Hi, in all the years playing KSP i've never done a challenge before. Soooooooo hydrofoil;s aren't mentioned not mentioned in the rules , therefore I tentatively enter my challenge cat,  with a score of 56.36037     mass 17.576 speed 144.3  parts 45

It goes a lot faster and does actually take off around 190ms which may be an issue, because then its a god awful aircraft

Got it, and adding it to the score list. Nice looking craft.

I could almost calculate the fuel efficiency score, but there's no indication of fuel usage per second. You've got mass and acceleration--which I can use to calculate thrust-- and velocity. Want to post another image showing fuel usage to get a fuel efficiency score?

[SpannerMonkey(smce)]

9 minutes ago, seanth said:

Ok. Revised rules up, and my first submission walks people through the score.

Got it, and adding it to the score list. Nice looking craft.

I could almost calculate the fuel efficiency score, but there's no indication of fuel usage per second. You've got mass and acceleration--which I can use to calculate thrust-- and velocity. Want to post another image showing fuel usage to get a fuel efficiency score?

just sorting out an IVA but i will get that image sorted soon, its probably horrible FE as it was being pushed by two panthers, though it didn't seem to be munching a lot of fuel, we''ll let the numbers decide, cheers

[seanth]

9 minutes ago, SpannerMonkey(smce) said:

just sorting out an IVA but i will get that image sorted soon, its probably horrible FE as it was being pushed by two panthers, though it didn't seem to be munching a lot of fuel, we''ll let the numbers decide, cheers

Oh, I don't know. I did some estimates on fuel usage based on the change in time and mass between two pictures and it looks like 1L/s ish. The thrust is around 17.18tonne*10.65m/s2=182.967kN. I'm getting a ballpark score of 26,402.1381, which beats my example submission

[Ezriilc]

Here's my first in.

I've been developing the "Orca" series since yesterday, but while the rules were still not set.  As it happens, I think this version (3.4) should do well in both categories.

Someone please check my math and tell me if I have these correct.

Part score:  297.89  (304.168 * 90.1 / 92)
Fuel score: 54,098.84  (2786 * 90.1 / 4.64)

BLAAM!

Orca 3.4  Download here:  http://www.Kerbaltek.com/users/Ezriilc/Orca 3_4.craft

Edited July 13, 2016 by Ezriilc
Rounded scores, changed kg to t.

[seanth]

MEGANewtons of thrust. Lol.

Math looks good to me. But does it have something _in_ the water? Those back fins look like they might be breaking the water's surface.

Edit. Oops. Part score is off. 304.168*90.1/92=297.8863

Edited July 12, 2016 by seanth

[Ezriilc]

1 minute ago, seanth said:

MEGANewtons of thrust. Lol.

Math looks good to me. But does it have something _in_ the water? Those back fins look like they might be breaking the water's surface.

 

I assure you, it is firmly on the deck (notice the climb indicator at zero, alt at 2m - the height of the probe core on the back) - and keeping it there is no small trick.  This thing is built to go as far as possible, so much of the starting mass is fuel.  When it gets light, it speeds up greatly, and at about 125 m/s she lunges for the sky (bad boat!).  On long trips, I plan to shut down the 4 Wheesleys at the stern and the top 4 Goliaths, and throttle back.

What I learned today:  Goliath engines take in so much air that they can provide all that the other 4 need - no scoops necessary!

I'd like to point out that with Orca 3.4, I could easily cheat the fuel score by shutting down some of my engines just prior to snapping the shot.  The fuel consumption rate would drop instantly, but the speed would take a while to bleed off.

[seanth]

1 hour ago, Ezriilc said:

I'd like to point out that with Orca 3.4, I could easily cheat the fuel score by shutting down some of my engines just prior to snapping the shot.  The fuel consumption rate would drop instantly, but the speed would take a while to bleed off.

Yeah, I know. We're going on honor a bit, here. Besides, you made your craft file available (kudos on that!) so people of a certain mindset could double check if they wanted. But, yeah. Cheating is possible.

[seanth]

Been messing with my latest entry and am having bouncing problems above ~45m/s. I suspect I know what is wrong, but it's proving tricky to fix.

[Ezriilc]

2 minutes ago, seanth said:

Been messing with my latest entry and am having bouncing problems above ~45m/s. I suspect I know what is wrong, but it's proving tricky to fix.

Bouncing, like "porpoising" (fore-aft oscillation)?  That is very common and I've learned ways to fight it, but you can never eliminate it completely, just change the speed that it starts - like a resonance.  The same can be said for "chine-walking" (port-starboard oscillation), which I'm currently working on with some frustration.

What I've learned:

Spoiler

• Make the ship absolutely rigid - it's far more important in boating than other KSP pursuits.
• Push the skis out to the edges of the craft to spread the stance.  I've been known to put them on stalks going out from the hull.
• Push heavy parts to the edges, away from the COM pivot point.
• Make the ship longer/wider to achieve the above.
• Reduce the angle of attack on the skis.  I find it's usually best to keep them to one click (5 degrees?) up from flat.
• Minimize the surface area of the skis to have just enough.

Good luck to you!  I need a challenge. 

Additional:  I'm currently working on some magic mojo to overcome high-speed chine-walking, in prep for ya'all taking the lead.

[seanth]

2 hours ago, Ezriilc said:

Bouncing, like "porpoising" (fore-aft oscillation)?  That is very common and I've learned ways to fight it, but you can never eliminate it completely, just change the speed that it starts - like a resonance.  The same can be said for "chine-walking" (port-starboard oscillation), which I'm currently working on with some frustration.

I was going to say I had never experienced chine-walking in my boats, but I just did. What I've mainly been facing is porpoising (really just the front end skipping and the oscillation builds up). I got the porpoising licked, and the speed shot up and, oh, hello chine.

For people experiencing the bow-stern oscillations:

Spoiler

• If you can, pump some fuel forward to make the front a little heavier. I am sure there are design solutions, but this was the easiest solution I came up with

 

[Ezriilc]

I think I've got chine-walking licked.  The key is to remove the chine altogether. 

Come on, let's see what you've got!