Plane Spin Issues

[Dunner Homes]

First time making an aircraft it is compact light with a center of mass behind the wings slightly, but despite centering the mass it begins to spin and is uncontrollable. It is 2 props and 1 medium engine. I have speculated that the lightness of the aircraft and the amount of props is causing it to gravitate toward upwards. Is there any way without changing the engine/2 prop design to create a controllable airplane?

[Ra-Ra-Rasputin]

Can you upload it? I could pull on my surgical gloves and have a bit of a look.
It's very very hard to tell from just an explanation what's going on.

[Delle(DK)]

you want to move the center of mass a tiny bit forward so in case your engines die, then you will nose down = speed and keep your plane become a glider. ( that is how they are designed in real life ) but its hard since you make center of mass one thing, but once you fill in fuel and cargo it moves backwards.
If you build the props in mirror mode then maybe try to remove the propellars and install them again " not in mirror mode" sometimes it happen that when building in mirror mode that things work against each other.

But in general my guess is that the problem maybs is not your engines, but maybe surfaces of your wings that are moving in the wrong direction... normal a plane do not flip crazy due to the engines but only due to the possition of the alerons/flaps and other things.. check that they all move in the right direction.. maybe you also need to use the Trim function and "nose down" a bit before you take off. Maybe try to fly with less power as well so engines are not so powerfull.

[Dunner Homes]

I would upload it but I can't seem to figure out how stormworks uploads designs to the workshop

[Ra-Ra-Rasputin]

Next to the save button there's a Steam Workshop upload button in the workbench. I'd also look at it now, but i've noticed it's 2:30 AM so it'll unfortunately have to wait a bit longer

[Dunner Homes]

This is the link https://steamcommunity.com/sharedfiles/filedetails/?id=2020703518
help and especially feedback on why its not working would be greatly appreciated since im p much a noob at this. The design is pretty much just for scouting/data and nothing else.

[Frizz]

Make sure you have your center of gravity behind your main wing. Also the tail fin may need a few more vertical rudders if your using the small ones.

When in doubt add more power!

[Ra-Ra-Rasputin]

Alright, after i've had my breakfast i'll take a proper look at that.

[Ra-Ra-Rasputin]

As i kind of expected, your tail simply didn't have enough drag, so i redesigned that, and your control surfaces were significantly oversized for the occasion.

https://steamcommunity.com/sharedfiles/filedetails/?id=2020920597

I... also fixed a few other things. I fixed your engine, fixed your wind indicator, added a small trim to the seat to compensate the fixed trim that i snuck in to your ailerons, completely bypassed the gyro (because it's not intended for planes) and... a few other tweaks. Unlike my usual style, i didn't use pink because structurally what i did wasn't all that much.

The reason it was shooting up into the air was the literal 5 tons of fuel in the back forcing the nose up. You won't see the effect in the center of mass calculation in the editor, so you have to expect it.

I also expect that if you cut the amount of fuel back there, you'll have to adjust the fixed trim (constant number) in some manner.

[Dunner Homes]

Thanks so much, I'm curious about how you recognized that the tail was not large enough, is there some sort of drag simulation or is it practice? The engine had heat issues before you used a gearbox to increase torque and lower rpm is that correct?

[Ra-Ra-Rasputin]

It's more based on how it behaved, so you could say experience... i have shy of a thousand hours toying with planes in Kerbal Space Program with FAR mod. The tail didn't have grip at all.

Basically tail grip is far more important than even the wings in a plane, as silly as that may sound, but think about it: All the airflow moving around the body is funneled toward it. It needs to drag to have purchase on the air and force stabilization (that's why it's there!). When you're building something relatively speedy as planes go, think less "plane that goes fast" and more "dart". It's why basically all the very fast planes you can think about practically have everything in their rear. With cases like the Blackbird basically just being widest at the rear.

For the engine, yes. While the plane almost chokes on slamming the prop pitch on full at the start now, by a happy accident turns out that 1:3 is about a perfect ratio for it. The engine runs much cooler when it doesn't have to run at such a high RPS. The downside is that you don't get it's beefy sound, and the upside is fuel savings. I think it'll be fine if you drop the ratio to 1:2 as well, you get more engine roaring probably without overheating.

[Dunner Homes]

After playing around and tweaking it today I know see what you were saying about the amount of fuel, you can reach the edge of the map and come back no problem. I will try decreasing its fuel and tweaking the trim and weight to see if I can fine tune it more.

[Dunner Homes]

When adding a system for altitude hold on the airplane. Since gyro is terrible for controlling pitch. Would I use a PID and connect it into the present system somehow, or use some other method? (Also thank you for pointing out the wind speed issue since I would never have thought about relative speed), is the constant -0.3 being added into the pitch the trim value

[ElfBossHogg]

One thing is that you may not need that amount of fuel to get to the edge and back. If you can find that sweet spot between prop pitch, throttle power, reverse-reduction gearing and fuel load you can go huge distances on smaller tanks. I'm currently working on a small plane experiment where a single medium engine using only one large standard tank can get over 300km at sustained speed of around 60m/s. It's sometimes not about how fast you can go but how smart you can. There's always a sweet spot you can find to get a job done efficiently.

[Ra-Ra-Rasputin]

Connect a PID to your pitch ailerons so that it bypasses your control, and make it watch your altimeter. Usually a keypad is pretty handy for setting the altitude you want to use. 0.4, 0, 0.02 should work for your plane, but i'm just estimating.

The constant -0.3 is the "hard trim", yes. It's because i had to limit (divide) your control to make it more stable.


Also i'm actually curious about making a very efficient plane too. I want to make platypus, but... flying. I'm currently working on a experimental jet that is decently fuel efficient, but it won't compare to a small diesel of course.

[Dunner Homes]

I wonder if you got high enough altitude initially whether you could for the most part glide using an engine intermittently to reduce velocity. I don't know whether the material in the game is light enough for this function but it could be explored.