[CHALLENGE] Delighttest. Lightest plane to Island Airfield

[azgar]

Hi, kerbal people!
I have a challenge for you today.
Let's build planes small and light.

The rules are as follow:

• Stock unmodded KSP2 has to be used.
• Build a plane capable of taking at least one kerbal from KSC to Island Airfield.
• Plane has to be landed at the airfield in one piece, without losing any parts.
• The goal is to achieve minimal take off weight (Total mass in VAB). Minimal empty weight (Dry mass) is a bonus.
   
• Post screenshots of your plane parked near Island Airfield hangars.
• Post a screenshot of recovery report.
• Post screenshots of the plane and engineering report in VAB.
• Have fun!

If you like, post a description of the plane, the story of development or even workspace file.
Good luck! May Kraken be kind to you!  

UPD: We have several submissions here:
 

mattihase	2023-03-08 22:59	Funtime Ride Chair	13	0.84	0.72	landed
Draradech	2023-03-09 00:17	Ultralight	9	0.55	0.53	landed
Socraticat	2023-03-09 04:29	Tiny Island Plane	17	0.72	0.58	landed
azgar	2023-03-07 19:00	Subflea	10	0.74	0.62	landed
azgar	2023-03-09 22:32	Nano unicycle	9	0.54	0.42	landed
Socraticat	2023-03-10 03:28	OneOscar	15	0.58	0.46	landed
Speeding Mullet	2023-03-10 05:11	Fly Safe	11	0.55	0.44	landed
Klapaucius	2023-03-10 12:25	Mini3	9	0.52	0.41	crashed
FlazeTheDragon	2023-03-10 16:00	HMS Jebediah	8	0.50	0.39	landed
weeee	2023-03-21 23:56	The Smollest Island plane	11	0.47	0.36	landed

 

Edited March 26, 2023 by azgar

[mattihase]

are launch clamps included in the mass calculations?

[mattihase]

Also Challenges is a different branch of the forum btw.

I think mods can move things between them though.

[Vanamonde]

5 minutes ago, mattihase said:

I think mods can move things between them though.

We can and we have. 

[mattihase]

I'll definitely post my final attempt tomorrow, once the VAB has remembered it's supposed to have a "Save/Load" GUI.

[azgar]

20 hours ago, mattihase said:

are launch clamps included in the mass calculations?

Everything that is on the start counts. And everything has to reach the Island Airfield and be able to fly back. Except fuel.
We have no refueling in KSP2, but assume we can replenish the consumables.
We could agree the plane has to do a round trip, but just getting there proves the airworthiness of the plane enough, I think.
And requirement to land twice might be too challenging for some ultralights  and more time/attempts needed.

[mattihase]

OK so the VAB didn't fix itself, and in fact got worse, so I'm submitting the last flight I was able to record before the game's code collapsed in on itself.

Behold the Funtime Ride Chair: This retro looking rocket looking chair with an air conditioning unit stapped to the back weighs in at 841kg with 25kg of that being jet fuel and 100kg being daring kerbonaut + suit. It features many luxury features such as landing fins, onboard phone charging and a constant stream of fresh air pumped past the pilot's body during flight. Also, a parachute set to facilitate and get in the way of landing. Supposedly a strut too so that the chair isn't just floating there but much to my frustration that seems to disappear sometimes during flight and I wasn't able to get a video of a flight with it in place.

Early iterations of the Funtime Ride Chair initially offered a design roughly supposed to offer user safety, placing the intake in front of the pilot for added forward protection, however for various bureaucratic reasons this prevented the pilot from escaping from the craft, this was quickly replaced with the much safer, more precarious seating arrangement you see in the final version.

On early test flights the Funtime Ride Chair contained up to 250kg of fuel, though as it was shown to be able to reach the island using as little as a bit over 30kg, engineers rounded that further down to the nice round 25kg present in the final design, shaving off 225kg of unnecessary mass.

 

After a couple missed attempts where clouds got in the way of aiming for the airstrip, Sidgel Kerman was loaded up for what would end up having to be the final attempt, documented here:

The flight path is pretty important to this. By cruising at around 5km up, the engine runs just about efficiently enough to get from the KSC to just off the shores of the island runway on the fuel that it has, where it wouldn't be able to reach quite as far at altitudes a kilometre lower or less. In the final stages of the flight over, the Funtime Ride Chair uses its landing fins to glide down to the target site before deploying its landing chute, bringing itself safely down to the ground in the same configuration it launched in. Also if you're wondering what that thing falling through the planet is, that's supposed to be Val in an earlier version of the Funtime landed on the beach, acting as a marker for what direction to fly in. Kerbin, however, hungers.

This is unfortunately where things end as KSP2 does not seem to want to work for me anymore. I had initially wanted to try landing it on top of the water tower, and made one more attempt at that off camera, getting pretty close... and then the game started refusing to load craft in the VAB and now refuses to recognise any of the workspaces I created in this save or launch anything from the VAB. However, aside from landing on top of the water tower, I've thought of some other improvements since that I'd want to try out if the game was more stable, such as replacing ?kg of battery and 100kg of parachute with 25 more kg of fuel, for powered landing and fully jet powered SAS. whether or not that would actually work aerodynamically, I don't know.

Final pic of the closest I could get to the tower:

 

Edited March 8, 2023 by mattihase

[Draradech]

0,53 dry / 0,55 fueled / 0,65 including Kerbal

Plane has no brakes, slow down needs to happen from wing drag at high AoA below takeoff speed.
No control surfaces, small reaction wheel + battery for control over the craft. That's also how it can balance on its singular wheel.
Wings are very slightly dihedral, which self-stabilizes the roll and yaw axis (against small deviations at least).

In flight:

Additional pictures:

Spoiler

"Landed" many times, I guess it's the wheel jittering

 

Edited March 8, 2023 by Draradech

[Socraticat]

No screenshots for this, but rather a nicely edited video (If I do say so my biased self). Seems I've been beaten by a gifted unicycle already today. I was hoping for first on this one today. BRAVO! I may still win by smallest footprint or something...

Total Mass: 0.72 t

Dry Mass: 0.58 t

"OneOscar" Fan Club

This here is a classic: "OneOscar FG+", Codename "Stubborn" designated so by its additional inline stabilizer. R & D wanted to not only get to the Island airfield, but do so with as little change to preferred course. Corey the tech swears it gets him there faster, but Ken and Charlie remind him that the maths just don't check out. Doesn't matter because Corey does mad stunts in his "OneOscar FG+" that make his momma proud.

Spoiler

 

 

Edited March 19, 2023 by Socraticat
"OneOscar" Fan Club Compliance

[azgar]

Great job!
Very cool ideas.
Let's see, how can we improve further
PS if someone has not yet posted their entries and these are heavier than The Unicycle (naturally they are!), don't hesitate to post. It's all about fun, rather than score.

[mattihase]

I definitely really underestimated the mass of a parachute, these ones are really mass efficient.

[Socraticat]

Your fuel needs were amazing. I bet I could use your flight profile to save on fuel. 

4 hours ago, mattihase said:

I definitely really underestimated the mass of a parachute, these ones are really mass efficient.

How much does the strut weigh? I bet you could get away with putting the seat on the tank, keeping the chute... is a spark smaller? The methalox tank is smaller... you could have smaller wings with your flight profile and...

 

Crap. Now I need to go play. Woe is me.

[azgar]

My own first attempt on a problem was like this:
Total mass 0.81t, fry mass 0.66t
Now it is totally humbled by the Draradech unicycle, right? And it had some controllability problems on a landing, it took me a bunch to iron these out.

Then I went to bicycle landing gear and smaller fuel tank, saving some mass and frankly improving on landing characteristics, though I had to manage roll quite carefully to avoid knocking my wing off.
The plane flew without SAS better than with it.
0.74t, 0.62t

Intermediate version was with Separatrons for engines. Flew quite well, but not well enough to get to the goal within weight limit.

Edited March 9, 2023 by azgar

[azgar]

And now something I have come up with after shamelessly copying all the best ideas we have had here:
The lightweight reaction wheel controlled unicycle. 
It is rather controllable, if you won't push it too far, then it spins and crashes. It requires SAS to stay in the air and on the ground.
It is quite hard to taxy on a ground. And it won't park, always tries to roll away, though I have the same problem with all my planes.
I suspect it's Kraken pulling invisible strings.
0.54 t, 0.42t and I could save a bit of weight by dumping some fuel.

Edited March 10, 2023 by azgar

[Socraticat]

Ok, a final attempt and edited video for now. I'll call this my final submission since it seems to be maximally reduced for this design. Kudos to all who participate in this one. It was a lot more fun than I anticipated. As an afterthought, I realize that all of this was possible with KSP2's new wing generation. It was so satisfying to fine tune the shape to my needs, and aesthetically I'm more pleased than I had anticipated.

Behold, "OneOscar"

(This is a "OneOscar SG Lite" to be precise .@azgar can you update standings to reflect the name change)

"Let's see your unicycle spin like this!"- Socraticat

Total Weight: 0.58 

Dry Weight: 0.46

"OneOscar" Fan Club

The lightest of the "OneOscar" Family of Biplanes and arguably the most popular variant, the "OneOscar SG Lite" can be seen here winning over the hearts of dozens, literally dozens, of short range commute enthusiasts and KSC employees. Keeping the front wheels fixed is optional, but encouraged for new owners. 

Fan Club history points to this very moment as the beginning of the "OneOscar" era.

Give a special thanks to @azgar for sparking the fire 

Spoiler

 

 

Edited March 19, 2023 by Socraticat
"OneOscar" Fan Club Compliance

[Speeding Mullet]

Great little challenge!  Took me a bit to figure out slow flight with such a small plane, the SAS seemed to be affected by the Kerbal moving his head or maybe I'm imagining things.  It made it too difficult to land with 1 gear so kudos to those that managed it!  Anyway:

Total Weight: 0.55t

Dry Weight: 0.46t

Mission report in full including engineers report and landing report.  The small landing legs bouncing while stationary appears to create "vessel landed" signals.  I could probably shave some weight off here and there and fly a cleaner profile, but this is about as min max as I can be bothered with

@azgar if you feel so inclined, a leader board would be great so people know where in the top 10 lightest to aim, but understand the theme is just to have fun!

SM

[Klapaucius]

It was definitely easier to land with no gear in KSP1.  I've come very close, but not got there yet. But for what it is worth 52T or 41 dry:

 

It just has slightly too high a stall speed and noses down.

[azgar]

@Klapaucius cool little plane!

Hope you manage to land it, so you can lead the scoreboard
Can you please post the list of parts?
There must be some way to build a plane with so many parts, yet so light.

[FlazeTheDragon]

Wet:  0.5t (0.41t with out kerbal, idk which one were going off, probs need to clarify)

Dry: 0.39t

Thing lands quit well, tho it does tip over once you come to a full stop :p Tho not really a big deal since nothing brakes.

Very fun little challenge!

Edit: Forgot to come up with the name  : HMS Jebediah

Spoiler

Spoiler

Spoiler

 

Edited March 10, 2023 by FlazeTheDragon

[Socraticat]

@FlazeTheDragon WOW! What's it like to fly that thing?

 

 

[FlazeTheDragon]

19 minutes ago, Socraticat said:

@FlazeTheDragon WOW! What's it like to fly that thing?

 

 

It actually flies pretty good, its pretty stable at slightly higher speeds and has a pretty low stall speed. Doesnt freak out sas either. Only real issue is that its got excessive slip angle at slow speeds if you try to roll, but its not enough to be a problem.

Oh yah, and its also supersonic xD 

Edited March 10, 2023 by FlazeTheDragon

[Socraticat]

2 hours ago, FlazeTheDragon said:

Oh yah, and its also supersonic xD 

 

Well... it's not a spin, but that is most certainly awesome!

Excellent!

[azgar]

I was trying all different combinations of wings, stabilisers and control surfaces and it seems to me that the mass is changing quite randomly.
I remove the part, stick it back to the plane and mass is not what it was before
Is that an engineering?
And I can't stick that much elements on a plane and still keep the mass that low too.
Can someone explain this thing to me?

Edited March 10, 2023 by azgar

[Draradech]

2 hours ago, azgar said:

I was trying all different combinations of wings, stabilisers and control surfaces and it seems to me that the mass is changing quite randomly.

Yah. My unicycle was 50kg lighter in the VAB before the flight. After revert to VAB it had the currently stated mass. Adding the parts up by hand delivers another number entirely. Something's off.

In your table in the top post, I believe most stated wet masses include the Kerbal. If so, mine should be 0.65 wet.

Edit: I see what's going on. The wings do change mass when resized, but only when launched. The engineers report doesn't update until revert to VAB. I think I might be able to get an even lighter craft. Experimenting with wing masses now.

Edit2: Yeah, it'll end up just like Flaze's design. 

Edited March 10, 2023 by Draradech

[mattihase]

On 3/9/2023 at 4:57 PM, Socraticat said:

How much does the strut weigh? I bet you could get away with putting the seat on the tank, keeping the chute... is a spark smaller? The methalox tank is smaller... you could have smaller wings with your flight profile and...

I'm not sure, though the strut was mostly for visual flair because I figured it wouldn't add too much, but it could definitely go.

Definitely with the wings as they are it glides pretty miserably at least until I deploy the chute but just about enough for it to get from flameout down to where it wants to land on the island.

 

I suppose the idea of gliding on parachutes could be quite fun if we had a microlight-style-chute like with KSP1's EVA parachutes. I wonder if those will be added at any point?

out of curiosity actually, @FlazeTheDragon @Klapaucius, I see you went with a similar seat sandwiched between intake and tank thing to what my earlier designs did. Did you manage to get a setup where the kerbal can actually EVA from the seat in that configuration?