The smallest propeller plane I could make

[MisterBennock]

Hello people,

after getting the Breaking Ground update I was thrilled to finally be able to build stock propeller planes! Well, the hype quickly died because it's pretty roundabout flying that stuff. So after making larger propeller planes and a P-38 replica that was actually flying pretty well (but with constant pitch adjustment), I decided to go simple and make very small planes that don't need THAT much input.

So I started by trying to replicate the Wright Flyers. Didn't work out as planned, I had to kerbalize it a lot. Also it still had too many parts (over 40!). Then I discovered an older jet design and just adapted that for propellers. And this is what happened:

It doesn't even have a name besides "Flyer 1". It is a fully functional plane, reduced to the essential parts (and one extra).

As you can see, it weighs only 622 kg and most of it are the wings/control surfaces. That is when I realized wings on Kerbin are made of rebar steel. Anyhow, I don't think I can go lighter without sacrificing aesthetics too much, (of course if someone has already made an even lighter craft, please tell me!). It has only 22 parts and all of them are necessary, except for maybe the solar panel on the top (visible in the picture below), because even without it the plane can fly around 1000 s, as the motor at 5 % output only uses up 80 mEC/s. And that is still enough to accelerate to around 54 m/s in level flight at 100-300 m. I haven't tried going higher yet, this thing is just for quickly jumping around. The other part that some might or might not consider necessary is the antenna, but I feel one belongs on every plane. What I haven't solved yet is the motor braking when I hit the brakes. I tried setting it to 0, but it still locks. Anybody know of a way to decouple it from the regular brake? I already have to kill the motor in flight and then brake so I don't get hit by the momentum when I have touched down. Also, it would be great to be able to set the torque/rpm in an action group without having to use the controller. Maybe it's a bug, but when I am using "absolute" in the custom field, it starts at 50 % and then pushing buttons makes it either 100 or 0.

And here it is in flight! I haven't made a picture from a landed one because with keyboard landing is extremely difficult and I still don't manage to nail it every time. I have to work on my skills.... and maybe connect a joystick again. Still flies like a charm (as much as the game allows). Of course the torque of the motor is still enough to give it a slight right roll, but I can trim it out mostly. And by default it's climbing under acceleration, so I even have to trim the pitch down.

And landed!

Also, feel free to talk about your microplanes!

Edited January 5, 2020 by MisterBennock
Added a picture from the landed plane

[GunnyErmy]

Cool plane!  I made a small prop plane once, but used 2 props to eliminate the torque, and 2 seats for fun, plus science, so mine was heavier at .836 tons.  Wanted to help you with your engine braking issue.  You'll want to remove the rotors from the brake action group.  As far as torque/rpm - I use the "main throttle" action group and add the rotors RPM limit to it.  This allows you to use standard Shift/Ctrl for RPM up and down, or z/x for max/min throttle.  Also, a useful extra tip - add the prop pitch to a translate action group - I use "translate up/down".  This is usually used for your RCS controls in space, but if set to prop pitch, you can adjust prop pitch up/down with i/k.  Hope that helps!

[Frank_G]

Very nice! Now make it foldable, pack it up and go for a ride on Duna

[MisterBennock]

21 hours ago, GunnyErmy said:

You'll want to remove the rotors from the brake action group.

Holy excrements, I've been playing KSP since 2013 and I have never once looked into the brake action group. I feel like a dumbass. Thank you, you did really help me. That other stuff - setting torque to main throttle - is exactly what I did right after I made that post (I was too lazy to edit). And pitch on translate is what I have been doing for the other planes like the P-38; the idea here was to have a slow fixed pitch plane so I only had to monitor one parameter.

 

17 hours ago, Frank_G said:

Very nice! Now make it foldable, pack it up and go for a ride on Duna

Haha, I think depending on what kind of carrier you are building you could just strap it somewhere on top/side. Foldable was something I experimented with, but even with KJR all the hinges and rotors are way too flimsy to be usable for stuff like that. So, no easily made folding wing/swing wing stuff.

[MisterBennock]

Inspired by @Frank_G's suggestion I tried making an even smaller plane (at the expense of aesthetics, though). This one is just called Micro 1. It weighs a bit more than the Flyer 1 because it's now on a push-pull system with an RTG in order to eliminate any kind of torque-induced roll and be able to operate in the dark. With each motor using only 0.08 EC/s at full output, the RTG is even a bit overkill. At least now it can fit in a Mk3 cargo bay without problems.

Note that the back propeller doesn't have a nosecone. That way one can add e.g. coupling devices.

I know this is not the one from the top, but the dimensions haven't changed.

And in flight! 1000 m ASL. Not visible on the pictures: The constant jittering of the autopilot. Since all controls surfaces are so close to each other, the plane is not easy to control. BUT IT'S FLYING!

[Frank_G]

Thats the spirit!  - Well done!

Back in the days where i played more frequently, i spent hours and hours to fit micro SSTOs into cargo bays for Laythe and Duna missions... Sadly, the physics model changed to much, that they don´t work anymore. I am sure, i will return to that in KSP 2, if it is an option to think, build, fly like in this lovely game...

[Zeiss Ikon]

On 1/5/2020 at 11:21 AM, MisterBennock said:

And in flight! 1000 m ASL. Not visible on the pictures: The constant jittering of the autopilot. Since all controls surfaces are so close to each other, the plane is not easy to control. BUT IT'S FLYING!

That layout (aside from the push-pull propulsion) reminds me a bit of the Bumblebee biplane that once held (and may still hold) the real-world record for smallest flying, crewed airplane (by dimensions) -- had a span less than two meters, and just about two meters long; just about 1.5 m tall on its fixed gear.  Teeny little heavily staggered biplane, reportedly a major PITA to fly.

[MisterBennock]

@Frank_G Very cute plane, looks awesome!

@Zeiss Ikon I just googled the Bumblebee... holy excrements I can't believe it actually flies. And I definitely believe that it's not easy to fly.

[NIGHTSWITCH]

cool