Props and Rotors

[Pds314]

Y'all ever just make a turbine that powers itself without an energy source?

Edited July 16, 2019 by Pds314

[KerikBalm]

On 7/12/2019 at 7:10 AM, fourfa said:

One nice aspect of this setup - just hit space again to feather the prop and shut down the motor for minimum drag.  Based on how thirsty the new LF motors seem to be

The LF motors are much less thirsty than I initially thought.

This is fuel cell powered, but as you can see, not thirsty at all:

The setup as you described would be thirsty. Rotor power or LF consumption seems to be a multiple of the Max RPM *setting" and the Max Torque *setting*.

If you only need 10% torque to reach the RPM limit, and you have max torque set to 100%, you'll use 10x as much fuel for no benefit. Likewise, if your rotor at max torque can only reach 230 RPM, and you have it set to a max of 460 RPM, you will use 2x as much fuel as you need.

I also encourage people, particularly for prop blades, to turn off pitch, yaw, and roll, you don't want them as control surfaces, you want them as a propeller. In the above example, I'm propelling a rather large craft with 4 standard rotors (which are fairly weak), so I can basically leave torque at maximum, since they won't hit the max RPM unit. I still have it pinned to throttle, for vertical takeoff and landing.

Now, I would encourage you to always have your props deployed, and bind control authority to an axis group (I use i/k) in progressive mode, not absolute. I'd encourage you to set them up so they have no bite when at 0 control authority (and have them start at zero). So you can then apply torque, and they spin up to max RPM without generating thrust. Then you can smoothly increase their bite with the axis groups, and adjust their control authority (= deployment amount) to your speed.

Now, always keep an eye on your RPM, if you can reach max RPM, back the torque setting back until its just enough that you don't start to lose RPM.

If you are torque limited, instead back off your max RPM until its just a little above what your motors can produce (as in the example above)

I use 2 control groups for the example above. In one mode, translate forward/back controls the nacelle tilt (for transitioning to and from hover), in the other mode, it adjusts max RPM, for reducing power in high speed flight (where the rotors can't reach max RPM anyway).

Once you get a hang of this, you can go around just basking in the sunlight:

and not using any fuel.

This should be good for use on Duna and Eve

[Loghogan]

1 hour ago, Pds314 said:

Y'all ever just make a turbine that powers itself without an energy source?

Wut...

 

How?

[Khonran]

On 7/15/2019 at 9:15 AM, Loghogan said:

I don't think so because I've build 4 different copters in the last couple days. All of them operate on authority limiters alone and they fly like a dream.

 

What's your secret? All my designs can take off fine but are completely uncontrollable once airborne. They pitch, yaw, and roll seemingly at random. I have to fight the controls constantly but eventually I crash anyway.

The blades stay deployed but I flattened the blades out in the hangar so they don't generate lift. I also set the authority to 0 and bind it to throttle. For flight I set the RPM limit to ~300 and bring up the torque. I let the rotor slowly reach the RPM limit then I slowly increase the authority. I then lift off real easy. I adjust the torque to maintain RPM but it doesn't matter because I'm already drifting like crazy.

I have a tail rotor that I thought I could use to trim any yaw caused by torque. Both motors are set to 1%. What am I doing wrong here?

 

Nevermind. Apparently the game doesn't like a single counter-clockwise rotor.

 

Edited July 17, 2019 by Khonran

[Loghogan]

23 hours ago, Khonran said:

What's your secret? All my designs can take off fine but are completely uncontrollable once airborne. They pitch, yaw, and roll seemingly at random. I have to fight the controls constantly but eventually I crash anyway.

The blades stay deployed but I flattened the blades out in the hangar so they don't generate lift. I also set the authority to 0 and bind it to throttle. For flight I set the RPM limit to ~300 and bring up the torque. I let the rotor slowly reach the RPM limit then I slowly increase the authority. I then lift off real easy. I adjust the torque to maintain RPM but it doesn't matter because I'm already drifting like crazy.

I have a tail rotor that I thought I could use to trim any yaw caused by torque. Both motors are set to 1%. What am I doing wrong here?

 

Nevermind. Apparently the game doesn't like a single counter-clockwise rotor.

 

@KhonranFirst, make sure your center of mass if directly under the rotor setup and that it is not really low or high, this will cause instability. If possible I recommend you try using contra-rotating props to eliminate extra torque. Also be sure you have bound the translate to authority limiter on the blades and use a play position with translate up and down with a Kal-1000 (If you want conventional engines and rotors, or you just like it like that). If you're still learning how to make copters I recommend starting with a fair amount of reaction wheels. But the best thing to do if you want great stability is having multiple rotors spaced out, like this drone for example. Best of luck, if you have anymore questions feel free to ask!

 

Edited July 18, 2019 by Loghogan

[Star-Eagle]

Has anyone tried using the rotors for wings? I've got an idea to use them to make folding wings for a lightweight glide return vehicle.

[Wjolcz]

46 minutes ago, Star-Eagle said:

Has anyone tried using the rotors for wings? I've got an idea to use them to make folding wings for a lightweight glide return vehicle.

Yep. They seem to be pretty flappy though. Unless you use autostruts to lock the wings rigid.

[Pds314]

On 7/16/2019 at 6:46 AM, Loghogan said:

Wut...

 

How?

Props use logic-free methods to increase efficiency in an unrealistic way. You can get 1000% mechanical efficiency with ease.

Regular surfaces do not do this.

 

I use regular surfaces to spin the prop. Basically a free energy turbine.

[Loskene]

17 minutes ago, Pds314 said:

Props use logic-free methods to increase efficiency in an unrealistic way. You can get 1000% mechanical efficiency with ease.

Regular surfaces do not do this.

 

I use regular surfaces to spin the prop. Basically a free energy turbine.

Oh that's clever, I like it a lot

[magnemoe]

15 hours ago, Pds314 said:

Props use logic-free methods to increase efficiency in an unrealistic way. You can get 1000% mechanical efficiency with ease.

Regular surfaces do not do this.

 

I use regular surfaces to spin the prop. Basically a free energy turbine.

Did not see any propeller in your design just the turbine of small fins. 
Assumed you used the turbine to drive the propeller and yes its genial. 

[Loghogan]

23 hours ago, Pds314 said:

Props use logic-free methods to increase efficiency in an unrealistic way. You can get 1000% mechanical efficiency with ease.

Regular surfaces do not do this.

 

I use regular surfaces to spin the prop. Basically a free energy turbine.

Neat

[Khonran]

On 7/17/2019 at 4:44 PM, Loghogan said:

@KhonranFirst, make sure your center of mass if directly under the rotor setup and that it is not really low or high, this will cause instability. If possible I recommend you try using contra-rotating props to eliminate extra torque. Also be sure you have bound the translate to authority limiter on the blades and use a play position with translate up and down with a Kal-1000 (If you want conventional engines and rotors, or you just like it like that). If you're still learning how to make copters I recommend starting with a fair amount of reaction wheels. But the best thing to do if you want great stability is having multiple rotors spaced out, like this drone for example. Best of luck, if you have anymore questions feel free to ask!

Thanks for the info. I did make some progress by making a contra-rotor design, and it was much more stable, but I'm still running into strange behavior in flight. The aircraft constantly wants to roll to one side and pitch up. The faster I go the worse it gets. It does let up when I reduce the authority limiter on the blades slightly but then I also lose altitude. Also, I have the pitch, yaw, and roll controls linked to the blades. I'm not sure if that's a good idea or not. But during flight rolling to the left also causes the aircraft to pitch down, while rolling to the right causes a pitch up behavior, and when I roll I also yaw. It's actually more effective to use the roll controls to control pitch than it is to use pitch controls. Maintaining a steady course, speed, and altitude is an insane balancing act of keeping the nose down, messing with yaw constantly to stay on course, rolling to control pitch and roll, and fiddling with the authority limiter of the blades to keep altitude and reduce what seems to be a retreating blade stall.

I haven't messed with the Kal-1000 just yet tho. My goal was to make a relatively low tech helicopter for short-medium range surface science contracts in career mode, so I'm trying to stick to early to mid game tech. I'll keep messing around with it tho, see if I can figure out what's going on.

[Azimech]

54 minutes ago, Khonran said:

Thanks for the info. I did make some progress by making a contra-rotor design, and it was much more stable, but I'm still running into strange behavior in flight. The aircraft constantly wants to roll to one side and pitch up. The faster I go the worse it gets. It does let up when I reduce the authority limiter on the blades slightly but then I also lose altitude. Also, I have the pitch, yaw, and roll controls linked to the blades. I'm not sure if that's a good idea or not. But during flight rolling to the left also causes the aircraft to pitch down, while rolling to the right causes a pitch up behavior, and when I roll I also yaw. It's actually more effective to use the roll controls to control pitch than it is to use pitch controls. Maintaining a steady course, speed, and altitude is an insane balancing act of keeping the nose down, messing with yaw constantly to stay on course, rolling to control pitch and roll, and fiddling with the authority limiter of the blades to keep altitude and reduce what seems to be a retreating blade stall.

I haven't messed with the Kal-1000 just yet tho. My goal was to make a relatively low tech helicopter for short-medium range surface science contracts in career mode, so I'm trying to stick to early to mid game tech. I'll keep messing around with it tho, see if I can figure out what's going on.

Welcome into the insane world of the KSP helicopter :-)

Take a look at what we've been doing before the DLC.

https://kerbalx.com/hangars/6515

 

And try this one.
https://kerbalx.com/Azimech/77I-Azi14-Asura-v22

Edited July 21, 2019 by Azimech

[Loghogan]

6 hours ago, Khonran said:

Thanks for the info. I did make some progress by making a contra-rotor design, and it was much more stable, but I'm still running into strange behavior in flight. The aircraft constantly wants to roll to one side and pitch up. The faster I go the worse it gets. It does let up when I reduce the authority limiter on the blades slightly but then I also lose altitude. Also, I have the pitch, yaw, and roll controls linked to the blades. I'm not sure if that's a good idea or not. But during flight rolling to the left also causes the aircraft to pitch down, while rolling to the right causes a pitch up behavior, and when I roll I also yaw. It's actually more effective to use the roll controls to control pitch than it is to use pitch controls. Maintaining a steady course, speed, and altitude is an insane balancing act of keeping the nose down, messing with yaw constantly to stay on course, rolling to control pitch and roll, and fiddling with the authority limiter of the blades to keep altitude and reduce what seems to be a retreating blade stall.

I haven't messed with the Kal-1000 just yet tho. My goal was to make a relatively low tech helicopter for short-medium range surface science contracts in career mode, so I'm trying to stick to early to mid game tech. I'll keep messing around with it tho, see if I can figure out what's going on.

I would recommend not using pitch yaw and roll on blades for now. The reason it could be rotating out of control is because you only have the authority limiters set on one side. if you have a two prop on booms like an Osprey. If you are controlling the authority with the slider I highly recommend binding it to and action group, I'll go more in depth about it later when I have the time.