I need someone who knows more about the mechanics of rigid bodies than I do

Let's add some mass (and drag) to the bottom to see if that fixes it.

Nope.

Making the craft pointed at the top seemed to make it turn over faster.

SAS is off in every photo.

The top of the vehicle is far wider than the center shaft of SAS parts you aren't enabling.

SAS does not help in this situation. If the craft is trying to precess, it'll do that, just more slowly (and with more power used). If the craft is trying to flip, it'll do that more slowly too, and with more power used.

SAS does slow it down. But it doesn't stop it.

Angling the top does seem to make it more stable, but it still points.

To get an efficient vehicle in KSP, the best bet is a shape similar to a drop of water. Point, small side up and it widens as you go down.

Your vehicles look too heavy and I don;t think you're getting enough deltaV.

Because you have chosen a vehicle design with fan blades, there is a torque going on, that even if you had SAS on, the flimsy center shaft is going to ave rotational energy and throw the whole thing out of equilibrium.

Making the bottom heavier does seem to help a little.

Now let's try with SAS on

SAS does help a LOT, but eventually it precesses and then it tips.

Try making a pseudo-asparagus staging space plane using batteries, solar panels and electric rockets.

the top of your craft is still to wide and flat. if its trying to travel upward the air presure is going to push down on one side, and cause lift on the opposite end, making your craft turn sideways like that. kindof like how a planes wing will create lift using high pressure on one side and low on the oposite.

This is an electric rocket.
It doesn't work.

Adding precession stabilisers + running SAS did help a lot (albeit at the cost of far less batterly life) but the thing did eventually turn over.

i believe this is what is happening in to you. you could consider adding a lip like ont he right to try to block the upward low pressure on one side, notice how adding a lip like this would make it slightly more rocket shaped, but thats the reason rockets are rocket shaped,

You just aren't going to be able to get a fan blade, electric rocket of that size and shape past 5000m without boosters.

if your craft was rocket shaped you wouldnt have this problem

Aspergers staging is irrelevant with batteries as electric power has no mass, and the mass of the batteries is damn near negligible.

Let's design it like a spinny rocket then, see what happens.

Huh. That DOES seem like it'd work. I'll try that next.

Spinnyrocket is complete shite because the center of lift is behind the center of mass. Makes 270m with SAS on.

you could consider adding smaller rotors above the top one to make it more resemble a rocket shape consider like this pic

forgot pic but im just spitballing

Kraken pls go

Hey, it looks like a palm tree.

And it doesn't have enough torque to get off the pad. Gimme a bit.

Adding lips seems to make it NOT generate lift.

I already know how to make a semistable one.
With the fins in close like this, and the thing balanced at the middle, it doesn't precess much.

It rises SLOW, and it does precess,
but if I stop holding E and turn on SAS, it stabilises pointing upwards, and I can resume ascending.

did you consider this, ? just extra rotors?

It looks dangerous at 2x time accel but it's stable enough that I can gain enough altitude that I can get it pointing straight up before it loses that altitude.

I think I have enough power to get this rotato potato to 5000m

More rotors = more weight and also more rotational drag. They DO mean more lift.

I don't know exactly why, but it seems there's a sweet spot about the # of rotors that maximises lift. You'd think the torque of the reaction wheels would exactly balance the drag, and the drag is directly proportional to the lift, but this isn't the case.

I know that putting the blades further out makes it go up faster. It also makes the fucker tip over.

You are going to get a torque on the center shaft that will limit its velocity to a snails pace and you won;t have enough electricity to get it up that slowly.

The torque on the center shaft IS what generates lift. It spins the fan blades, which push the air down.
Rotato potato breaching 3000m
As the air gets thinner, this thing's upward force reduces.
Which is strange, because the thinner air should also reduce the drag of the rotation, which would let the wings spin faster

Rotato potato with 1/2 its charge, breaching 4000m.

If you want to know why this craft is semistable, despite it having no angles and looking nothing like a rocket, and despite SAS being off,

it's because if there's any thrust that isn't along the axis, it gets balanced out by the rotato spinning.
The torque that makes it precess (and eventually tip, I think?) comes from the angle the thing's center of mass (gravity) makes with its center of lift (thrust).
Here, those two are almost exactly at the same point, meaning there's very little torque.

SAS is off to save power. It's largely unnecessary, given that SAS would drain power trying to correct the minor wobbles that the thing spinning corrects for anyway.

but thinner air means theres less air for you to push off of to rise higher

Remember what generates force here?
Spinning fan blades.
Less air = faster spinning.

Anyway, with more than 75% of its fuel spent and after 15 bloody minutes, Rotato Potato has risen above 5000m
Without angled wings
without looking like a rocket

The thing is actually stable at this altitutde, possibly because the little girders at the middle are damping precession, possibly because of the air resistance on the shaft.
With SAS off, of course.

Thing is, this is my best attempt BEFORE asking Veeky Forums.
It's slow as fuck.

I've gotten 20m/s, 24m/s rotatos compared to this thing's 6m/s ASL.
But those rotatos flip over.

Rotato potato in free fall. Keeps the same attitude as the other flippy things, roughly. There's probably a relation.

Found a use for SAS :^)
Keeps the thing pointed up as it falls without it needing to spin (which stops it falling)

By spinning the thing (with SAS off) at a very precise speed as it approached the ground, I was able to get my landing speed to somewhere like 2m/s.

The rotato, a purely electric-powered full body rotater, has landed.

I even rolled it back to the launch pad.

Now Veeky Forums

Help me make it go faster.

Maybe try adding a third propeller around the middle?

/kspg/ go back to sucking cat benis and eating snake poo
shoo shoo /kspg/
not even good enough for /kspg/
so shit all the mods hate you /kspg/
mexican scam artists /kspg/

Are you using an even number of blades?
I'm not sure if it matters unless it's a ducted fan, but you should be using an odd number of blades.

Holy shit it's fucking stable at sea level and I have no fucking idea what I did different

Well I added more rotors. But that should make it LESS stable.

There typically is one, comprised of 2 rotors rather than 8.
This makes it so that the craft has a "long axis" and a "medium axis" of rotation.

The short axis (the axis about which the craft rotates easiest) is along the shaft.
But by adding those wings at center mass, the "medium axis" is along those wings (making the craft flip end over end through an axis through the middle wings)
And the "long axis" is normal to those wings, the craft flipping end over end with the middle wings also flipping.

As you probably know, objects do NOT like to spin along their middle axis. The momentum gets transferred to the long and short axes.

As this craft precesses, it's spinning (very slowly) along its long and medium axes. Both the same spinning rate. But the medium axis transfers SOME of that rotation to the short axis.
This damps the precession.
And the fucker is stable.
I think.

It may well be the drag forces of the shaft itself, as the shaft's drag forces try to stop the precession too.

I'll try an odd number of blades.

Lemme read up why I should do that.

Oh, blade wobble being synched with shaft wobble.

Yes, that does matter for this. It's not the synched wobble that causes problems
(see )

In fact, synched wobble may well damp the thing's precession. Still, it's worth trying.

I'm going to get something above atmosphere using only electric power and decouplers somehow.

Probably by sticking a Plaid decoupler payload on top of a fan blade ascender.

If I use plaids from the ground, then re-entry forces explode whatever I launch. Also it's not very cost OR mass efficient since it takes something like 30 tons of decoupler to deploy a 1 ton payload to 22000m.

If I fly the plaid up to, say, 14,000m on one of these rotatos, then the re-entry forces are gonna be less, and I might well be able to breach atmosphere.

Hell, I might even be able to make orbit, Plaids propel things at 2500m/s or more and that's orbital speed, it just gets damped quickly by the atmosphere.

I'd need a second plaid at periapse to circularise the orbit, but I swear I'm going to find SOME way to get SOMETHING into orbit without using Solid fuel, Liquid fuel, Xenon, or Monopropellant.

From this high up, you can see the curvature of the planet.

>As you probably know, objects do NOT like to spin along their middle axis. The momentum gets transferred to the long and short axes.

If the whole thing is spinning and the rotation axis is the same as the direction in which you are flying, it actually should make it more stable

That it is, That it does, But it precesses, and the magnitude of the axial tilt increases until physics decides that I can't simply copy one of those for some reason
(Despite them fucking working IRL)

Flight ceiling seems to be 12km.
Still, not bad.

For the exact same torque I can get like 3x the speed if I build wider blades (as wider blades move faster). If I could get them to be stable, I might get up to 14km with one of these.

It certainly has a better cost-to-payload ratio than Plaids, given that I recover like 90%-98% of the value depending how many parts break, compared to plaid's fucking 10%.

Oh, yeah what works irl might not work in KSP and vice versa.
I havent played it in a while and cant judge the physics in the recent version, but playing it with the mod FAR was always a huge improvement to the stock aerodynamics

Lol yes. In kerbal space program, a craft with the exact same shape can have different drag characteristics.

Stick a Flea directly to the underside of the CENTRAL POINT of your command pod.

Compare with sticking the flea just slightly off the center point, and using rotation/movement to get it centered.

The latter has FAR more drag.

Why? Because the top of the flea is producing drag in that case, and it isn't producing drag when you stick it to the bottom hardpoint.

It's quite Lel, but every piece generates its lift and drag completely independently, and the game cancels the lift from e.g. the top face of a thing if there's something stuck right in the middle of that top face.

What exactly did you change to fix your issue

>playing meme space simulator
>not working for NASA and launching real rockets
fucking pleb