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Post by SuburbanSB on Feb 14, 2015 9:27:25 GMT
The issue brought up originally here, stated that; I now realize everything was blowing the wrong direction because the art is backwards from what it should be! Very frustrating, but I'm sure you guys will fix this.  In the thread I investigate this issue my self, and discover that propellers (rotated in the correct direction, that is when placed on the side of a block, it points vertically not horizontally) Will create thrust in the opposite direction to that of the block. a direct copy/paste from the thread. Okay, so the first image, is where nothing is changed, and the blocks have just been placed as per usual. This is the improper placement for the propeller, this results in the machine 'twitching' and spinning out. The second image is where the propellers have been rotated. This is the proper placement for movement back and forth. This issue here however, is the blades are moving in a clockwise direction, which appears that the machine should go backwards, however it in fact goes FORWARD?! This third photo shows the spinning blocks having been flipped. It looks as if the machine will be going forward now as the blades are going anti-clockwise, thus 'pushing' air out the back, and creating thrust. This however is not the case. This does appear to be an issue, and a bug, and thus should be moved to the bug section! 
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Post by pdcwolf on Feb 14, 2015 15:27:07 GMT
The art is not "backwards", the propeller is symmetric, which is worse (no way to know which way is the correct one). The real issue is the propeller not showing correctly which way is forwards because of it's extreme (and unrealistic lol, most propellers have a way to tell you which way is forward) symmetry. It's cool how oversimplifying stuff generates problems too, which shouldn't be the case. In fact, the way this propeller is modeled, it probably wouldn't generate much thrust anyways, no matter which direction you spin it.  I'd suggest changing the art to something more one-directional, and creating an opposite one too since we are here, for pusher and counter-rotating designs. |
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Post by darek4488 on Feb 14, 2015 20:15:19 GMT
Today I was building a two-engine plane and I noticed that it is freaking impossible. First of all since there is no mirrored propeller we can't make one spin left, other right and have both of them push the same way. If you make them spin different directions your plane will be spinning on the spot. Moreover if you make both propellers spin the same way you will make them both push or pull however you will also end up with huge forces flipping your aircraft on the side, because apparently those Aerodynamic Propellers have mass and inertia exactly like they'd be carved out of stone.
Now what you need to do to fix things is create a second propeller. We need to have left and right spinning propellers to make successful planes and helicopters. You should also tweak the mass of the propeller and counter-acting forces, because it is bonkers that a one-engine plane would flip on its side as soon as its propeller starts spinning.
Also it would be nice if we could start and stop the spinning blocks.
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Post by beigealert on Feb 15, 2015 0:17:41 GMT
Today I was building a two-engine plane and I noticed that it is freaking impossible. First of all since there is no mirrored propeller we can't make one spin left, other right and have both of them push the same way. If you make them spin different directions your plane will be spinning on the spot. Moreover if you make both propellers spin the same way you will make them both push or pull however you will also end up with huge forces flipping your aircraft on the side, because apparently those Aerodynamic Propellers have mass and inertia exactly like they'd be carved out of stone. Now what you need to do to fix things is create a second propeller. We need to have left and right spinning propellers to make successful planes and helicopters. You should also tweak the mass of the propeller and counter-acting forces, because it is bonkers that a one-engine plane would flip on its side as soon as its propeller starts spinning. Also it would be nice if we could start and stop the spinning blocks. If you push "R", it'll actually flip the propeller around, not just rotate it. EDIT: Erm, this is before you place it. No way to re-orient them after you've placed them unfortunately.  |
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Post by SuburbanSB on Feb 15, 2015 0:52:10 GMT
Alright... so I decided to get cosy with a bit of paint... and came up with this to try help explain what is going on... Red arrow: Direction the propeller is travelling at that given point. Blue lines: Movement of the air around the propeller Green arrow: Thrust that SHOULD be generated by the propeller, moving in that direction.   As it is calculated, when the propeller is moving in a clockwise direction, it should go backwards, However it in fact goes forwards! And when the propeller is going in an anti-clockwise direction, it should generate thrust to go forward, where it actually goes backward. Anything else that should be noted...? |
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Post by pdcwolf on Feb 15, 2015 2:49:44 GMT
Alright... so I decided to get cosy with a bit of paint... and came up with this to try help explain what is going on... Red arrow: Direction the propeller is travelling at that given point. Blue lines: Movement of the air around the propeller Green arrow: Thrust that SHOULD be generated by the propeller, moving in that direction. -snip- As it is calculated, when the propeller is moving in a clockwise direction, it should go backwards, However it in fact goes forwards! And when the propeller is going in an anti-clockwise direction, it should generate thrust to go forward, where it actually goes backward. Anything else that should be noted...? Yo', propellers are modelled so perfectly symmetric they shouldn't generate any thrust, independently of which direction you spin it. In your paint you are ignoring the fact that the propeller has another side. Give me a moment and I'll come back with some badly drawn paints too. They may help Back with what I promised. This is a representation of the airflow around the propeller. Airflow direction is right to left. Green is the airflow at the tip, blue is at the middle, red is at the base.  Now, this is what a real propeller (5x5e for high rpm electric motors, no need to go into specific with what the numbers mean unless you want me to) looks like, won't even bother explaining the differences, they are extremely noticeable. Hell, you can just google "5x5e" to see more of this prop. You can clearly see in which direction it should spin, in fact you can spin the other way around and it'll generate thrust, just not as much as spinning it correctly.  |
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ryu
Peasant
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Post by ryu on Feb 15, 2015 3:14:53 GMT
I am here for support of the opposite propeller so I can finally build a quad-copter how I want it.
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Post by SuburbanSB on Feb 15, 2015 3:58:19 GMT
pdcwolf You make a strong case for your point, and I'll give you that... I still, personally believe it would give you thrust, despite how symmetrical it is, and how little thrust it may give. Perhaps yes, if the propellers are angled, say at 30 degrees, it would give substantially more thrust. However, I must admit you appear to have more knowledge on the topic than I, therefore I will accept what you are saying. Although admittedly, we are kinda of discussing the same idea... that the propellers are not quite right in this game, and could be adjusted to better give a more realist appearance/design.
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Post by pdcwolf on Feb 15, 2015 4:09:39 GMT
Yeah, we both want to get to the same thing at the end of the day. The problem is where they to keep the same propeller model, someone will come with the exact same problem and ask for it to be flipped around again. You seem to be reporting this problem as if the propeller had a front and a back, and it doesn't, and that needs to get fixed too. I'm both showing that flaw (which you didn't notice lol) and asking for it to be fixed by remodeling the propeller instead of flipping the thrust around (and suggesting them to make a flipped, counter rotating variant since we are here).
As a footnote, the way the propellers work in this game, they don't give more thrust by adding some rotation to them which is counter intuitive, but totally understandable given how the engine works. They actually give less thrust. Flying panels however do react correctly and they even allow for the construction of a variable pitch propeller and even counter-rotating ones.
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Post by SuburbanSB on Feb 15, 2015 4:23:50 GMT
Ahhh, I see where you are coming from now  I'll just make a note to it on the main post then. |
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Post by pdcwolf on Feb 15, 2015 4:30:18 GMT
Further proof for the footnote on my previous post: a.pomf.se/dikmpb.webmFor anyone who could possibly not get what's going on: I'm using counter rotating spinning blocks, then I place steering blocks on those spinning blocks to control the pitch of the "propellers", then I use flying panels as the actual propellers. When they rotate in the ground with a propeller symmetrical to the airflow, nothing happens. Then I create pitch by moving the steering blocks and thus rotating the flying panels respective to the airflow, they start diverting air downwards (actually one could go deeper explaining this but there's no need) and thus the machine flies. If the propeller model is kept, then they should work like this at least (except that more aggressively and reliably, otherwise they would have no use against flying panels). |
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Post by darek4488 on Feb 15, 2015 13:07:34 GMT
Today I was building a two-engine plane and I noticed that it is freaking impossible. First of all since there is no mirrored propeller we can't make one spin left, other right and have both of them push the same way. If you make them spin different directions your plane will be spinning on the spot. Moreover if you make both propellers spin the same way you will make them both push or pull however you will also end up with huge forces flipping your aircraft on the side, because apparently those Aerodynamic Propellers have mass and inertia exactly like they'd be carved out of stone. Now what you need to do to fix things is create a second propeller. We need to have left and right spinning propellers to make successful planes and helicopters. You should also tweak the mass of the propeller and counter-acting forces, because it is bonkers that a one-engine plane would flip on its side as soon as its propeller starts spinning. Also it would be nice if we could start and stop the spinning blocks. If you push "R", it'll actually flip the propeller around, not just rotate it. EDIT: Erm, this is before you place it. No way to re-orient them after you've placed them unfortunately. Looks like you don't understand what the issue is. A rotated propeller is still the same thing that it was. It remains a clockwise propeller or counter-clockwise propeller. Take a look at this picture of a pair of CW and CCW propellers. If you flip them they will still propel the same direction. It is the spin direction that differs them.  So right now if I need to make a pair of propellers with opposite spin to equal out the forces I simply can't, becuase in game we only have a clockwise propeller. The issue that pdcwolf has mentioned is the pitch angle and it is a different thing. Basically all helicopters have a collective pitch mechanism that allows them to have change the lift without changing the speed of the blades. Moreover helicopters have flat blades and it is possible for them to have no lift or even a negative lift with the same spin and speed of the rotor. Planes have fixed pitch propellers and they operate on the engine speed. However those fixed pitch propellers need to come in pairs as there is a clockwise and counter-clockwise variant.  So ideally we should have 3 different propellers: -flat one with variable pitch angle -fixed one working clockwise (currently in game) -fixed one working counter-clockwise |
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Post by darek4488 on Feb 15, 2015 15:22:17 GMT
Guys, I have also noticed weird things about the gyroscopic precession acting despite having no tilting forces in the system. I am adding pictures and a .bsg save file of a helicopter that the effect occurs on. imgur picsWhen I change the collective pitch to give me lift it always flips the whole machine left. Does anybody know what is the source of the problem? The centre of the mass is exactly below the main rotor and on the same height as the tail rotor. The speed of the tail rotor is setup to counter the main rotor torque. controls are: right shift - up right ctrl - down y - fire Attachments:Helicopter.bsg (5.88 KB)
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Post by pdcwolf on Feb 15, 2015 18:31:57 GMT
The issue that pdcwolf has mentioned is the pitch angle and it is a different thing. Basically all helicopters have a collective pitch mechanism that allows them to have change the lift without changing the speed of the blades. Moreover helicopters have flat blades and it is possible for them to have no lift or even a negative lift with the same spin and speed of the rotor. Planes have fixed pitch propellers and they operate on the engine speed. However those fixed pitch propellers need to come in pairs as there is a clockwise and counter-clockwise variant. So ideally we should have 3 different propellers: -flat one with variable pitch angle -fixed one working clockwise (currently in game) -fixed one working counter-clockwise Yeah, what I'm going at is that the actual propeller is flat, yet it generates thrust, so this problem is incorrectly reported as "thrust being generated in the wrong direction", it's not just the direction, the entire thing is incoherent and prone to causing confusion. Btw, CCW propellers became way less popular with brushless motors given you can just change the spinning direction while keeping the prop facing the same way thus having freedom to set it either for push or pull. The picture I posted has the engine and prop set up for a push configuration, yet the prop is a normal CW one. So yeah, there's 2 ways to solve this: What you just suggested, 3 propellers. or just the flat and being able to rotate it freely given we can already change the spin direction of the motors in game. |
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Post by darek4488 on Feb 15, 2015 21:45:43 GMT
pdcwolf What you are saying is also incoherent especially including something like a brushless motor which doesn't really apply to the game. To developers trying to fix all those aero-problems I would suggest creating: -a single engine plane controlled by engine speed and flaps -a dual engine plane controlled by engine speed and flaps -a single rotor helicopter with a tail anti-torque rotor and with collective pitch control (skip the cyclic pitch now, because it is too complex) -a tandem rotor helicopter (design similar to Boeing CH-47 Chinook) You will then know all our problems. I feel a bit disappointed that at the moment we can do mainly quadcopters.
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I now realize everything was blowing the wrong direction because the art is backwards from what it should be!
I'll just make a note to it on the main post then.