totm jan 2024 Minimalist Planes

[Donmy Kerman]

@RoninFrog You don't have to fill both rules 1 and 2. Eve/Jool craft are totally fine.

Edited August 3, 2023 by Donmy Kerman

[RoninFrog]

1 hour ago, Donmy Kerman said:

@RoninFrog You don't have to fill both rules 1 and 2. Eve/Jool craft are totally fine.

Gotcha.  Duna it is then! 

Spoiler

On 7/12/2023 at 5:23 AM, The Dressian Exploder said:

The theoretical limit?

(Not a submission, just what might be possible with enough careful flying and inclusion of rocket engines on a plane... 2 parts!)

Hold my empty command pod

1 part, 12 minute flight over 17km.  Fills rules 2, 3, 4, 5, and 6 as stated

 

[Donmy Kerman]

@RoninFrog Cool loophole! Will add to the leaderboard. What's the cost of a kerbal though? I'm assuming 6 funds for the EVA fuel but the rest of the kerbal is expendable.

Edited August 3, 2023 by Donmy Kerman

[RoninFrog]

4 hours ago, Donmy Kerman said:

@RoninFrog Cool loophole! Will add to the leaderboard. What's the cost of a kerbal though? I'm assuming 6 funds for the EVA fuel but the rest of the kerbal is expendable.

Most ksp players consider the price of a kerbal life to be approximately zero, but the cost of the mk1 command pod I used would be $600 according to the wiki.  I'm not really sure how my submission should be scored as I can't provide pictures and cost of a kerbal in the VAB, so I'll leave it up to you.

[OJT]

I've done some low mass and low cost optimized missions, but surprisingly never attempted low part count challenges. Seeing as this one would be relatively quick to do, I hopped in and designed this. Precisely 14 parts in this

We take off from KSC runway and head towards the Island
 

Spoiler

Gentle touchdown and full stop to confirm successful landing
 

Spoiler

Let's return to KSC runway
 

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The long way around
 

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A small boost at the top and we enter a stable Low Kerbin Orbit. Yes, this is officially a SSTO
 

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Couple of orbits later, we perform a small deorbit burn and reenter the atmosphere
 

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If you the reentry correctly, you can glide all the way towards the runway without even using the engines. I undershot a bit, but seeing as I have plenty of fuel and that I wouldn't be allowed to land empty anyway, I engaged the engine to get to my destination
 

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Another gentle touchdown and another successful landing. Panel at the top right corner on last screenshot shows that the plane wasn't empty of mission critical resources
 

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So yeah, the first SSTO capable craft here. And I would be delighted by this achievement if it wasn't for the fact that I initially tried to fit the 10 part limit. But at least the way I tried to do it, 10 part SSTO that satisfies this challenge's rules is borderline impossible. In the various designs that I tried out, it either didn't have enough fuel, didn't have enough landing wheels to stay upright, or it would fly so unstable that it needed constant SAS intervention. And SAS uses a lot of EC. And I couldn't put a solar panel or fuel cell to recharge it because I had to sacrifice some other crucial part in order to put that. And RAPIER (and Twin Boar in my alternative concepts) annoyingly doesn't have an alternator... you get the gist. At the end, I had to concede and go for higher part count, but that made my personal goal way too easy. This plane, in fact, flew stable enough that it barely needed any SAS to hold steady, so fuel cell was pretty much useless: with very careful inputs I think you can do it with just cockpit's EC and with 13 parts. But better safe than sorry I guess?

If any of you know a possible way to make a 10 part SSTO that fits within this challenge's rules, I would like to hear your suggestions/see your attempts

... perhaps you guys might be interested? @QF9E @camacju

 

[Donmy Kerman]

@OJT Nice SSTO! This is pretty much what I envisioned when making this challenge. Will add to leaderboard.

[camacju]

4 hours ago, OJT said:

... perhaps you guys might be interested?

you could use a Big-S wing and control the craft just through gimbal and reaction wheel, that would save 5 parts or so. Also maybe remove the battery and just use the cockpit internal battery?

[QF9E]

You can also replace the 3-part landing gear with a single modular girder segment XL. Or any other part that has a high impact tolerance, forms a relatively stable platform and has limited drag.

To prevent excess drag, you could use a Mk2 or Mk3 cargo bay as impromptu landing gear - you can land a craft on their open cargo bay doors. Although the Mk2 and Mk3 form factors may not be the best choice for low part craft.

[QF9E]

9 part SSTO:

Craft file: https://kerbalx.com/QF9E/Low-part-count-SSTO

I used a girder as a skid rather than a conventional landing gear, which saved me 2 parts compared to @OJT's submission. For the wing I used a single Big-S wing which doubles as a fuel tank, which saves me another 2 parts. And I flew the entire mission on the capsule battery, which saved a further part.

To save on electricity I switched off the reaction wheel during atmospheric flight - I didn't need it as the control surfaces offer ample control by themselves. And I carefully balanced my craft so that on re-entry only a small amount of electricity was needed for the reaction wheels. I used the Precise Position mod to position my wing so that its center of mass / lift is eactly on the centerline of the craft.

The lack of landing gear means you don't have much control over the craft on the ground, which necessitated a careful approach and landing on the Island Runway, in order not to run out of runway for the subsequent takeoff. And I almost overshot the KSC runway as my speed was a bit high - I knew from testing that the landing skid tends to explode when touching down at over 80 m/s.

Edited August 6, 2023 by QF9E

[Donmy Kerman]

@QF9E The KerbalX link doesn't work so I don't know the cost of your craft.  Edit: found craft cost.

Edited August 6, 2023 by Donmy Kerman

[OJT]

7 hours ago, QF9E said:

9 part SSTO:

Craft file: https://kerbalx.com/QF9E/low-part-count-ssto-3

I used a girder as a skid rather than a conventional landing gear, which saved me 2 parts compared to @OJT's submission. For the wing I used a single Big-S wing which doubles as a fuel tank, which saves me another 2 parts. And I flew the entire mission on the capsule battery, which saved a further part.

To save on electricity I switched off the reaction wheel during atmospheric flight - I didn't need it as the control surfaces offer ample control by themselves. And I carefully balanced my craft so that on re-entry only a small amount of electricity was needed for the reaction wheels. I used the Precise Position mod to position my wing so that its center of mass / lift is eactly on the centerline of the craft.

The lack of landing gear means you don't have much control over the craft on the ground, which necessitated a careful approach and landing on the Island Runway, in order not to run out of runway for the subsequent takeoff. And I almost overshot the KSC runway as my speed was a bit high - I knew from testing that the landing skid tends to explode when touching down at over 80 m/s.

Are you playing on the latest version? Because when I tried the girder/plate trick for the landing gear, it exploded way before I could even achieve sufficient speed to get airborne. Maybe their strength values have been adjusted after some update? Or maybe I'm just doing something wrong lmao

[QF9E]

2 hours ago, OJT said:

Are you playing on the latest version? Because when I tried the girder/plate trick for the landing gear, it exploded way before I could even achieve sifficient speed to get airborne. Maybe their strength values have been adjusted after some update? Or maybe I'm just doing something wrong lmao

I'm using version 1.12.5.3190 which as far as I know is the current version. I do run a couple of mods, but nothing that should change parts. But to be on the safe side I just tried without mods: my craft still takes off like it should.

The impact tolerance for the Girder XL should be 80 m/s, as shown here: https://wiki.kerbalspaceprogram.com/wiki/Modular_Girder_Segment_XL. My SPH shows the same value:

In light of all this I don't think it is something on my side. Maybe the girders have been inadvertently changed by some mod or other in your install?

 

Or perhaps there's an issue with your craft. What is the takeoff speed of your craft with normal landing gear? Mine takes off at about 60 m/s, and the girder does explode as expected at 80 m/s if I don't take off in time.

And how did you place the girder? It should be placed such that the back end of the girder is only a little behind the center of mass of your craft. Too far back and it will be impossible to pull up the nose during the takeoff run.

Not saying you do this, but I see many videos of KSP players who place the main landing gear of their SSTOs (or, in this case, the back end of the girder) so far back that it is impossible to pull up the nose during a take-off run. Many players just run their SSTOs straight over the end of the runway, only pulling up once over the edge. This technique will not work when you're using girders for landing gear as the speed will be too high by then.

 

 

2 hours ago, Donmy Kerman said:

@QF9E The KerbalX link doesn't work so I don't know the cost of your craft.  Edit: found craft cost.

Thanks for the heads-up. I renamed the craft in KerbalX and I did not realize that this changes the link to the craft. The correct link is https://kerbalx.com/QF9E/Low-part-count-SSTO

Edited August 6, 2023 by QF9E

[OJT]

1 hour ago, QF9E said:

Or perhaps there's an issue with your craft. What is the takeoff speed of your craft with normal landing gear? Mine takes off at about 60 m/s, and the girder does explode as expected at 80 m/s if I don't take off in time.

And how did you place the girder? It should be placed such that the back end of the girder is only a little behind the center of mass of your craft. Too far back and it will be impossible to pull up the nose during the takeoff run.

Not saying you do this, but I see many videos of KSP players who place the main landing gear of their SSTOs (or, in this case, the back end of the girder) so far back that it is impossible to pull up the nose during a take-off run. Many players just run their SSTOs straight over the end of the runway, only pulling up once over the edge. This technique will not work when you're using girders for landing gear as the speed will be too high by then

Mine took off at about 95ish m/s. That probably explains it. Seems like Big-S Tailfins don't provide enough lift to take off at lower speed. I'll try experimenting a bit more when I get free time

[QF9E]

It turns out my little 9 part spaceplane is quite a bit more capable than I originally thought: it is able to reach orbit twice without refueling. So here's a flight from KSC via Low Kerbin Orbit to the Island Runway, then back to the KSC via a second LKO.