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The Efficient Airplane Challenge


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I enjoyed @Klapaucius's Inefficient Airplane Challenge but it made me feel dirty. So I've turned it upside down. 

Get from the runway to the Island airfield burning as little fuel as possible. 

There will be two leaderboards. 

1. Overall Fuel Used. 

2. Fuel Used / Take Off Mass. 

Scoring

1. Any fuel you take with you will count as used. So only take what you need. 

2. Give me a shot of your ship in the SPH or on the runway stopped with a view of the fuel on board. 

3. For Leaderboard 2, I also need its mass to be in the shot.

The Rules: 

1. Your craft must be Kerbaled and Command Chairs are not allowed. Use a Command Pod. 

2. It must use a stock engine (non-electric) as its sole source of propulsion. No glitch/kraken/ladder drives. You can use trubo props, but you must attach propellers to the stock nodes and not use offset. 

3. Don't catapult your Kerbal (there's another challenge for that).  That being said, you can expend parts as needed and I won't give you a hard time if you break something on landing. In fact, as long as your kerbal survives, I'll count it.  See rule 6 regarding Leaderboard 2. 

4. For the purposes of this challenge I'll count any dry land on the island as acceptable, and I'll count "landing" as touching down. So, if it rolls into the water after landing, I'll give it to you. As long as Jeb survives.  

5. No bailing out. Your pilot must remain in the Command Module until touchdown. 

6. For Leaderboard 2: Due to mass calculation, you must carry all parts to the island. Losing parts on "landing" is acceptable. 

7. Enjoy

Leaderboard 1 Turbo Prop: 

@OHara 0.6

 

Leaderboard 1 Jet: 

@swjr-swis 1.65

@camacju  1.7

@ralanboyle 2.2

@ColdJ 4

 

Leaderboard 2 Jet:

@ralanboyle 0.00050

@18Watt 0.0008

@Klapaucius 0.0011

@camacju 0.0014

@ColdJ 0.00287

 

Leaderboard 2 Turboprop: 

@ralanboyle 0.00017

@OHara 0.00020

Edited by ralanboyle
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@ralanboyle Here's a submission without a turboshaft. It uses a Juno engine and a drag occluded fairing.

The general flight profile is to get to just under Mach 1 to avoid any transonic drag losses then cut the engine and cruise the rest of the way to the island airfield. I didn't get the timing quite right -  you'll see I had quite a bit of speed excess at the airfield, meaning I boosted too long.

wkhRnI8.png

Craft in VAB. It weighs 639 kg and has 3.6 units of liquid fuel.

3t5uNtD.png

On runway, with 3.6 units of fuel loaded

iVlpTns.png

Boosting up to just under Mach 1

yjFKZxS.png

Engine cut - glides the rest of the way to the airfield

Z4jjYi6.png

Pulling up to maintain speed

fLNWFx3.png

Detaching the fairing, deploying chute

2KQhmpq.png

Landed - 1.06 units of fuel used

 

Edit - I completely missed the requirement that there are no command seats allowed. Guess I'll redo this with a command pod :/

Edited by camacju
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Ok, new submission with command pod:

7WkpJal.png

In VAB, mass 1117 kg

PSVUtbC.png

On runway, 5.4 units of fuel loaded

3ZO5oK0.png

Boost ended

vAf31Gd.png

Boost was just short of the airfield so I did a second boost. Probably not the most efficient way to go

2Mw5Qw2.png

Fairing and parachute deployed

41RAY8U.png

Landed with 3.04 units of fuel left, 2.36 units of fuel used, and no parts broken.

I think some possible improvements would be:

-Instead of a boost to Mach 1, cruise for a bit at a lower speed and have a bit more wing area to reduce energy lost to drag - maybe?

-Figure out how to boost for less fuel - better takeoff profile, etc

However, if this challenge were to be repurposed for a longer run, then the optimal flight profile would change significantly. Maybe have Dessert Airfield / Baikerbanur (for non-DLC friendly) as well as Island Airfield destinations

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Alrighty @camacju

As you know, your first submission is disqualified due to the Command Chair. 

Your second entry is great.

It earns 5.4 on the first leaderboard. Remember Scoring rule 1. All fuel you take with you counts.

It earns  0.0048 on the second leaderboard. 

Edited by ralanboyle
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Howdy @ralanboyle!  I have an entry for leaderboard 2, although it won't make the top slot.  Takeoff weight is 101,360kg (101.360t), and was loaded with 240 units of LF.  Should give me a score in Category #2 of 0.0024.

Screenshots:

  Reveal hidden contents

If I manage to beat the high score for Category #2 I'll post again.  By the way, my game is 100% stock, with BG and MH expansion packs.  

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@ralanboyle, Whelp, that didn't take as long as I thought it would.  I think you can put me at the top of Category #2.  Takeoff weight of 102,379kg (102.379t..), with a fuel load of 120u LF.  That gives me a score of .0012!  There was about a teaspoonful of fuel left when I landed, but I made it!

Screenshots:

  Reveal hidden contents

I am frankly surprised that I was able to do better with a jet than turbo-props.  

Also, a design note:  I originally planned to make the fuselage out of Ore Tanks.  Sadly, when I launched it, the loaded Ore Tanks were not able to hold themselves together, the plane self-destructed as soon as it loaded.

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  On 5/12/2021 at 5:38 PM, 18Watt said:

I am frankly surprised that I was able to do better with a jet than turbo-props.

Expand  

I have found jets to always been more efficient than props in KSP. I'd be interested to see someone prove me wrong.

Also, I am glad you went for a heavy plane. Theoretically the most efficient plane for leaderboard 2 should be enormous.  Now, I get to try again...

Edited by ralanboyle
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  On 5/12/2021 at 11:04 PM, ralanboyle said:

Now, I get to try again...

Expand  

I suspect you and @camacju will be able to knock me off the top if you want.  One suggestion if you’re interested would be to tuck a small ore tank in there- surely camacju can fit just one more thing in the coffee can? Might end up needing a few more drops of fuel.  I’m amazed at how much you can do with just a few units of fuel.

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Coffee can planes just won't be as efficient as a Goliath powered plane, because the Goliath is larger but has higher specific impulse.

The ideal plane for fuel/mass would probably be something like:

Single Goliath powered, engine is occluded and a shock cone is used for drag purposes instead
As many fairing occluded parts as possible to reduce drag
Big wings

While the ideal plane for raw fuel consumption would probably be something similar to my earlier design but with bigger wings and a better flight profile.

Edited by camacju
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Ok, here's a quick new submission. I added more basic fins and reduced the initial fuel load to 2.1 units, but left the craft otherwise unchanged. (This is to leave room for later improvement)

4lKYX6l.png

In VAB. 2.1 units of fuel, 1188 kg - score of 0.0017

PatQvwQ.png

Boost is done, throttling way down to cruise at about Mach 0.5 for the rest of the way. You can see that most of the fuel is used here

OUN9Y4g.png

Cruising further - I might have been able to cut the engine here actually, but I wanted to be sure of making it to the airfield. I definitely could have launched with 1.9 units of fuel however

7opXqXW.png

Engine cut - I have a lot more energy than I need here

n72Jkkj.png

Parachute deployed

6oz6jW0.png

Landed

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After some ill fated design changes, I managed to get Jeb to the island airfield on just 1700 mL of fuel.

QFI1stw.png

1184 kg start mass, 1.7 liters of fuel - score is 0.0014

5Jr5ynL.png

Boost to 110 m/s - this is the point where I can maintain level flight at a -1 degree pitch, which minimizes drag and thus minimizes thrust needed. I keep the throttle at about 5-6% for the rest of the fllight

1ngsbsV.png

Engine flames out at this point so I point horizontal to maximize lift to drag ratio and thus glide distance

oC84WH6.png

I'm barely able to glide to the airfield at which point I deploy the parachute just like normal. However I come in a lot lower this time because of the reduced fuel

Oq0Gsuu.png

Landed and no parts broken

Without a pretty major design change, I probably won't be able to improve at all on this design. However I am thinking of some potential changes to this craft. Mainly I want to reduce mass as much as possible. This will reduce the amount of fuel I use for takeoff and for the initial boost, as well as reducing wing area which will cut drag. I can't really think of any other way to improve this.

The benefit of this mass reduction is apparent in the command chair craft that I mistakenly tried to enter - it used significantly less fuel than this craft even though it had a much less optimized flight profile

Edited by camacju
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  On 5/10/2021 at 1:49 AM, ralanboyle said:

If [turboshafts] unbalance the score then I'll give them their own leaderboard.  

Expand  

The Breaking  Ground propellers allow a way to make perpetual motion machines (bug tracker link) by offsetting the propeller blades to be closer to the rotation axis.   If we limit the props to their default placement, though, turboprops have similar fuel efficiency to jets --- they just get that efficiency at lower speeds.

My unimaginatively-named 'single engine propeller' plane on KerbalX  launching at 2.292 t with 1.2 units (6kg) of fuel can reach the island runway.  0.52 units per tonne.

8WRD3xU.pngyXvz7b2.pngC0mlOqT.pngtY9PlJ9.png

As per the contest rules, I wheelbarrowed on landing and rolled into the ditch. 

Edited by OHara
2.18t of the craft survived the trip off the runway
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Entering the MinLF-165, a single-Juno jet to transport one kerbal in a command pod from the KSC runway to the Island, for (1) 1.65 units of LF, scoring (2) 0.0011 on efficiency.

Vd54kYO.png

 

 

  Reveal hidden contents

 

Full album: https://imgur.com/a/iMZzJeq

Craft file: https://kerbalx.com/swjr-swis/MinLF-165

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Here's another craft operating on mostly the same design I had before, but stripped down as much as possible. Inflatable airlocks aren't the most comfy, especially when they're deflated with Jeb inside them, but they are really good for fuel efficiency.

Xflsr4e.png

In VAB. 1.3 units of fuel remaining, just above the turboshaft entry, with potential to go down even further. 722 kg mass - this won't win any mass efficiency awards but I'm not going for that.

5N9P8vb.png

Airlock is extended on runway

Ye35Ip6.png

Jeb gets out of a conveniently placed rover and then the airlock is retracted with him in it, so it can fit in the fairing. Kerbals must be very flexible

uOBYJEb.png

Lower weight means less wing area, and thus less drag + thrust at a faster cruise speed - great for efficiency

v6VJPTW.png

Engine cut with 0.24 fuel remaining - 1.06 fuel actually used (equal to my command chair entry!), and it's possible that it might be pushed below 1 fuel

th0ixpW.png

Parachute isn't the most efficient option but it's certainly the easiest

5Xx6CWf.png

Landed

Edited by camacju
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@ralanboyle, I see @swjr-swis knocked me off the leaderboard for Category 2.  Temporarily..

I have improved my big lifter for Leaderboard #2.  Takeoff mass 122,900kg (122.9t), with 100u LF.  That's a score of 0.0008.  Should put me back at the top of Leaderboard #2.  Probably only briefly...

Screenshots:

  Reveal hidden contents

I chose the MKI cockpit because it seemed like it would be very crash-worthy.  Just in case.  I normally try really hard to land airplanes in one piece, but I had a feeling this one was going to be close..

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  On 5/13/2021 at 3:24 PM, camacju said:

Jeb gets out of a conveniently placed rover and then the airlock is retracted with him in it, so it can fit in the fairing.

Expand  

(How are you retracting the airlock with a kerbal inside? The option disappears from the PAW, and a set action group doesn't work at that point.)

Never mind... just noticed the 'deploy limit' can be added to a translation axis.

 

  On 5/13/2021 at 10:14 AM, OHara said:

launching at 2.292 t with 1.2 units

Expand  

Kudos. The KSP props still entirely elude me. I seem to need at least six of those blades on that same engine to even get enough speed for take off, on a lighter plane, and it burns through its LF before even being over water. All the while the plane is fighting my controls like it's possessed.

 

Edited by swjr-swis
ah... deploy limit
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Congratulations everyone for your entries today! Due to the close race, please include 5 decimal places in #2 scores. 

Congratulations to @OHara for holding the current top score in both leaderboards. Let's try to match min with a jet, if more people start entering prop planes and widening the gap, I'll create another leaderboard for them. I am surprised by this efficiency. Good work. 

@swjr-swis, great run and great plane. Unfortunately, it does not qualify for #2 because of dropping its landing gear. 

@camacju, I like the "outside the box" thinking but your kerbal does not remain inside a Command Pod and therefore violates rule 5 and the spirit of the challenge. 

Edited by ralanboyle
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  On 5/13/2021 at 11:58 PM, ralanboyle said:

@swjr-swis, great run and great plane. Unfortunately, it does not qualify for #2 because of dropping its landing gear. 

Expand  

Hmm ok, that rule got added while I was busy creating/flying/uploading the entry. Makes sense though.

 

  On 5/13/2021 at 11:58 PM, ralanboyle said:

if more people start entering prop planes and widening the gap, I'll create another leaderboard for them. I am surprised by this efficiency.

Expand  

I'm not surprised, props should be more fuel efficient. I did start one to give OHara a bit of direct competition, but I just can't make those props work properly. There's some clue I'm missing about making them produce the thrust they should be capable of, and KSP does nothing to explain what.

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  On 5/10/2021 at 1:14 AM, ralanboyle said:

1. Your craft must be Kerbaled and Command Chairs are not allowed. 

Expand  

This is what you said. There wasn't any specification that it needed to be a command pod, just not a command chair. Airlock is not a command chair

  On 5/10/2021 at 1:14 AM, ralanboyle said:

5. No bailing out. Your pilot must remain in the Command Module until touchdown. 

Expand  

Oh, is this what you meant? The pilot remained in the command module from takeoff to touchdown. Surface operations before takeoff were never mentioned either, nor did the pilot bail out of anything.

Edit: I mean, I could just launch with a command pod bolted on, transfer the pilot, and detach the command pod. That would satisfy the spirit of the "no bailing out" rule while adding absolutely no change to the mission at all

Edited by camacju
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