[Stock Helicopters & Turboprops] Non DLC Will Always Be More Fun!

[Gman_builder]

Just now, MatttheCzar said:

The problem I had was that the blades couldn't "seesaw" like on a real gyro or heli.  I was using IR for my bearing.

Do you mean actuate?

Ya it's pretty much impossible to build a stock swashplate and linkages to actually actuate the rotor disk.

Side note, IR is really bad for making turboprops and bearings. The free moving docking washer has a RPM limit built into it so your really not going anywhere using that. Even as a gyrocopter's rotor you wont generate enough RPM to get off the ground.

[MatttheCzar]

10 minutes ago, Gman_builder said:

Do you mean actuate?

Ya it's pretty much impossible to build a stock swashplate and linkages to actually actuate the rotor disk.

Side note, IR is really bad for making turboprops and bearings. The free moving docking washer has a RPM limit built into it so your really not going anywhere using that. Even as a gyrocopter's rotor you wont generate enough RPM to get off the ground.

It actually did get off the ground, its just that the disemmetry of lift forced it into a destructive diagonal spin.  Trying to make a swashplate with two additional free washers made it get off the ground, but it was more like when you build a rocket with a low CoG, uncontrollable and spinny.  Stayed in the air for more than a minute though!

Spoiler

 

 

 

Edited July 26, 2016 by MatttheCzar

[Pds314]

Building a swashplate would be quite difficult I imagine. It means the helicopter blades need to be on bearings, the swashplates need to be on a fixed ball joint or universal joint and need to be connected with a bearing, the rotor needs to be on a bearing (duh) and the control rods need to be on bearings.


All in all, a 2-bladed chopper ends up needing:

at least two, but probably four, pilot input control rods. (It might be possible to use control surfaces for these) These need to be essentially linear motors, which are quite complex to make and control if control surfaces cannot be used.

A universal joint or ball bearing for the swashplates.

A bearing for the swashplates.

2 control rods, with a bearing at the bottom and another bearing at the connection point with the blades.

2 blades, each with a bearing.

A bearing to hold the rotor.

All in all, this is a minimum of about a 8 craft and 9 bearings in a multiply linked assemblage spinning at high speed with substantial torques and forces on every single part.

[Pds314]

Made an actuator. Works surprisingly well and is even controllable with SAS. In fact, it even attempts to balance on a point if given a thruster.

Edited July 26, 2016 by Pds314

[Gman_builder]

1 hour ago, Pds314 said:

Building a swashplate would be quite difficult I imagine. It means the helicopter blades need to be on bearings, the swashplates need to be on a fixed ball joint or universal joint and need to be connected with a bearing, the rotor needs to be on a bearing (duh) and the control rods need to be on bearings.


All in all, a 2-bladed chopper ends up needing:

at least two, but probably four, pilot input control rods. (It might be possible to use control surfaces for these) These need to be essentially linear motors, which are quite complex to make and control if control surfaces cannot be used.

A universal joint or ball bearing for the swashplates.

A bearing for the swashplates.

2 control rods, with a bearing at the bottom and another bearing at the connection point with the blades.

2 blades, each with a bearing.

A bearing to hold the rotor.

All in all, this is a minimum of about a 8 craft and 9 bearings in a multiply linked assemblage spinning at high speed with substantial torques and forces on every single part.

Ya that's exactly what I was saying. Someone did however make a fully functional collective pitch helicopter swashplate with IR. The part count without a turboshaft engine was immense already. So it wouldn't be applicable in a aircraft. But it was proof of concept I guess. It worked really well.

Your little model is kind of a swashplate but kind of not as well. It's more of a Universal Joint made for helicopter functionality.

Side note, current helicopters use a Fixed Pitch rotor head, which is inefficient and less responsive than a collective pitch rotor head so that could be something to work towards.

Fixed Pitch = fixed blades that use engine throttle to control thrust. Used in RC helis and models.

Collective Pitch = Engine is always at full throttle. Actuators and servos are used to control the pitch of the blades, intern controlling thrust. Used in REAL helicopters and VTOL aircraft. Also used in high performance/high value RC's and model.

Collective pitch rotor heads:

Imgur Album.

Fixed pitch rotor head:

Imgur Album.

 

 So obviously the bottom one seems much simpler. Because it is. But in KSP, constantly changing the RPM could lead to engine failure. So, my theory is this. somehow engineer a collective pitch swashplate and linkages. Then you can keep the engine at a constant RPM, minimizing risk of failure.

The only problem, obviously.... is how do you engineer such a device in a game with broken physics and screwed up part collisions?

 The world may never know....

 

 

Theres something wrong with Imgur right now so the images don't show. Oh well.

 

[Pds314]

7 minutes ago, Gman_builder said:

Ya that's exactly what I was saying. Someone did however make a fully functional collective pitch helicopter swashplate with IR. The part count without a turboshaft engine was immense already. So it wouldn't be applicable in a aircraft. But it was proof of concept I guess. It worked really well.

Your little model is kind of a swashplate but kind of not as well. It's more of a Universal Joint made for helicopter functionality.

Side note, current helicopters use a Fixed Pitch rotor head, which is inefficient and less responsive than a collective pitch rotor head so that could be something to work towards.

Fixed Pitch = fixed blades that use engine throttle to control thrust. Used in RC helis and models.

Collective Pitch = Engine is always at full throttle. Actuators and servos are used to control the pitch of the blades, intern controlling thrust. Used in REAL helicopters and VTOL aircraft. Also used in high performance/high value RC's and model.

Collective pitch rotor heads:

Imgur Album.

Fixed pitch rotor head:

Imgur Album.

 

 So obviously the bottom one seems much simpler. Because it is. But in KSP, constantly changing the RPM could lead to engine failure. So, my theory is this. somehow engineer a collective pitch swashplate and linkages. Then you can keep the engine at a constant RPM, minimizing risk of failure.

The only problem, obviously.... is how do you engineer such a device in a game with broken physics and screwed up part collisions?

 The world may never know....

 

 

Theres something wrong with Imgur right now so the images don't show. Oh well.

 

Wait, so to clarify, does a collective pitch rotor change the combinaed blade pitch AND cyclic pitch? I'm aiming to do this:



Which is hideously complicated, but may be doable. The big problem I've found with fixed or simple variable pitch rotors is that as the helicopter reaches high forward speed, the center of thrust goes off center because the blade going into the wind is developing much more thrust than the one going out of it, especially on large rotors.

This can be solved by using cyclic pitch systems, which is why the swashplate is needed.

Edited July 26, 2016 by Pds314

[Gman_builder]

1 minute ago, Pds314 said:

Wait, so to clarify, does a collective pitch rotor change the blade pitch AND cyclic pitch? I'm aiming to do this:



Which is hideously complicated, but may be doable.

That picture is of a fixed pitch rotor head. The "pitch" is referring to whether or not there is a cyclic to change the pitch of the blades as throttle input, instead of using variable engine power to spin the disk at different speeds. A collective pitch swashplate is comprised of TWO separate plates that are linked together. The bottom plate controls attitude input, and the top plate controls throttle input.

That diagram is strange though. As normally you would have 2 cyclic controls instead of the 4 seen here. 1 servo for pitch, and the other for roll. Yaw is controlled by the tail rotor.

You can clearly see the cyclic controls but no throttle controlling linkages.

 

[EpicSpaceTroll139]

22 minutes ago, Gman_builder said:

 

Fixed Pitch = fixed blades that use engine throttle to control thrust. Used in RC helis and models.

Collective Pitch = Engine is always at full throttle. Actuators and servos are used to control the pitch of the blades, intern controlling thrust. Used in REAL helicopters and VTOL aircraft.

Actually the engine doesn't stay at full throttle, but rather changes to maintain a target rpm. Climbing takes greater blade pitch -> more blade drag -> more power than hovering, however the the rotor rpm remains the same. If the engine always was at maximum throttle, the rotor would probably rip itself apart when a heli tried to descend as there wouldn't be much pitch --> drag on the rotor and it would be getting all that power, which would make it spin faster and faster. This is why there is a throttle on helicopters in real life (some helicopters do it automatically though.)

 

Also referring to the last previous post: with 4 linkages you don't need a second swashplate, you can just shove the single one up with all 4 linkages at once to perform collective inputs

P.S. I like your car but this is only here bcc mobile won't let me get rid of it.  V

On 6/17/2016 at 7:05 AM, Gman_builder said:

Edited July 26, 2016 by EpicSpaceTroll139
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[Gman_builder]

1 minute ago, EpicSpaceTroll139 said:

Actually the engine doesn't stay at full throttle, but rather changes to maintain a target rpm. Climbing takes greater blade pitch -> more blade drag -> more power than hovering, however the the rotor rpm remains the same. If the engine always was at maximum throttle, the rotor would probably rip itself apart when a heli tried to descend as there wouldn't be much pitch --> drag on the rotor and it would be getting all that power, which would make it spin faster and faster. This is why there is a throttle on helicopters in real life (some helicopters do it automatically though.)

P.S. I like your car but this is only here bcc mobile won't let me get rid of it.  V

Well ya but it is essentially the same as staying it constant throttle. So you guys get some frame of reference here, I am basing all my knowledge about helicopters off the Sab Goblin 380 I own. Which, I know, is RC but the rotor head assembly is basically exactly the same as the ones used on real helicopters. Same principles at least.

[EpicSpaceTroll139]

With 4 linkages to the swashplate it can perform both cyclic and collective control.

[Gman_builder]

4 minutes ago, EpicSpaceTroll139 said:

With 4 linkages to the swashplate it can perform both cyclic and collective control.

hold up friend, if al the linkages are attached directly to the bottom swash, it can't move more than two ways at once. So forward backward and side to side. It cannot perform throttle control from the same plate as the cyclics are linked too.

Edited July 26, 2016 by Gman_builder

[EpicSpaceTroll139]

52 minutes ago, Gman_builder said:

hold up friend, if al the linkages are attached directly to the bottom swash, it can't move more than two ways at once. So forward backward and side to side. It cannot perform throttle control from the same plate as the cyclics are linked too.

...uh...but it doesn't move sideways... It tilts... It tilts in whatever direction and goes up and down. I don't see the problem. From most helicopter hub mechanisms I've seen (well, diagrams and pictures), this is how it works on almost all helicopters.

Imagine placing a paper plate on top of 4 pincels (for the sake of simplicity imagine the plate can't rotate around, only tilt). You could raise the front pencil and lower the back one or Vice Versa to tilt the plate forward or backward. You could raise the left pencil and lower the right or Vice Versa to tilt it right or left. You could raise or lower all of them to move the plate up or down. Or you could do any combination of these movements to move the plate up and down and tilt it in any direction. It's that simple. You could even theoretically do this with only 3 rods connecting to the bottom plate. 

Edited July 26, 2016 by EpicSpaceTroll139

[Pds314]

1 hour ago, EpicSpaceTroll139 said:

...uh...but it doesn't move sideways... It tilts... It tilts in whatever direction and goes up and down. I don't see the problem. From most helicopter hub mechanisms I've seen (well, diagrams and pictures), this is how it works on almost all helicopters.

Imagine placing a paper plate on top of 4 pincels (for the sake of simplicity imagine the plate can't rotate around, only tilt). You could raise the front pencil and lower the back one or Vice Versa to tilt the plate forward or backward. You could raise the left pencil and lower the right or Vice Versa to tilt it right or left. You could raise or lower all of them to move the plate up or down. Or you could do any combination of these movements to move the plate up and down and tilt it in any direction. It's that simple. You could even theoretically do this with only 3 rods connecting to the bottom plate. 

Again, theoretically only 3. In practice, you want 4 because trying to maintain a constant pitch on each blade is not going to be very effective.

Speaking of which, I think my bearing prevents pitch changes from working properly, I think the proper way is to not use the bearing but instead hold the swashplate directly on the control surfaces, then use the deploy control to adjust fixed pitch.

Edited July 26, 2016 by Pds314

[Gman_builder]

1 hour ago, EpicSpaceTroll139 said:

...uh...but it doesn't move sideways... It tilts... It tilts in whatever direction and goes up and down. I don't see the problem. From most helicopter hub mechanisms I've seen (well, diagrams and pictures), this is how it works on almost all helicopters.

Imagine placing a paper plate on top of 4 pincels (for the sake of simplicity imagine the plate can't rotate around, only tilt). You could raise the front pencil and lower the back one or Vice Versa to tilt the plate forward or backward. You could raise the left pencil and lower the right or Vice Versa to tilt it right or left. You could raise or lower all of them to move the plate up or down. Or you could do any combination of these movements to move the plate up and down and tilt it in any direction. It's that simple. You could even theoretically do this with only 3 rods connecting to the bottom plate. 

Ya I meant tilt sideways. I guess that makes sense. But like I said, i'm basing my knowledge on my 1000 dollar toy. Obviously that is not the best model.  

20 minutes ago, Pds314 said:

Again, theoretically only 3. In practice, you want 4 because trying to maintain a constant pitch on each blade is not going to be very effective.

Speaking of which, I think my bearing prevents pitch changes from working properly, I think the proper way is to not use the bearing but instead hold the swashplate directly on the control surfaces, then use the deploy control to adjust fixed pitch.

That's why I said my helicopter has two swashplates with 2 linkages attached to the bottom plate and 2 to the top. Using a single linkage on your throttle axis can lead to unequal blade pitch and bad stuff.

[Azimech]

From page one of this topic, February 11 2015.

"Completely stock. I'm still having problems with the control rod hinges, they're not flexible enough. Swash plate control is a problem too: the landing gears can only be toggled."

 

But we're past those problems now, right? Good luck with it guys :-)

[Gman_builder]

15 minutes ago, Azimech said:

From page one of this topic, February 11 2015.

"Completely stock. I'm still having problems with the control rod hinges, they're not flexible enough. Swash plate control is a problem too: the landing gears can only be toggled."

 

But we're past those problems now, right? Good luck with it guys :-)

See! I knew it!

[Pds314]

4 hours ago, Gman_builder said:

So obviously the bottom one seems much simpler. Because it is. But in KSP, constantly changing the RPM could lead to engine failure. So, my theory is this. somehow engineer a collective pitch swashplate and linkages. Then you can keep the engine at a constant RPM, minimizing risk of failure.

The only problem, obviously.... is how do you engineer such a device in a game with broken physics and screwed up part collisions?

 The world may never know....

 

Wow. I managed to build the mechanism and test it at low speed.

It's hideously complex, with no less than 13 stock hinges and a floating swashplate that isn't on hinges AT ALL, and it still needs work to be rugged enough for flight, but...

The Swashplate is above the blades in this one. I decided to do it that was mostly based on what was easy to fit where. Probably best NOT to do it that way.

Again, I want to stress just how absurdly many moving parts there are. 2 swashplates, the rotor shaft, each of the 4 rotors and each of the 4 control rods. That's 11 moving parts, plus the base craft.

[Gman_builder]

23 minutes ago, Pds314 said:

That would have taken me a week to do jees

Seems like your building style consists mainly of REALLY offset parts. Cool.

[Pds314]

Just now, Gman_builder said:

That would have taken me a week to do jees

You're probably not gonna believe this, but it worked out of the box. I built the swashplate assembly first, and once that was working, I built the rotor assembly and the collective worked at low speed on the first try. =D

[Azimech]

5 minutes ago, Gman_builder said:

Seems like your building style consists mainly of REALLY offset parts. Cool.

To each his own I guess :-)

Functional but not very pretty IMHO. At least some struts can give the illusion that parts are fixed instead of magically floating.

[Pds314]

Just now, Azimech said:

To each his own I guess :-)

Functional but not very pretty IMHO. At least some struts can give the illusion that parts are fixed instead of magically floating.

Yeah. I mostly am prototyping, so I don't worry about where parts would realistically have to attach. It can be fairly ugly.

[Gman_builder]

20 minutes ago, Azimech said:

To each his own I guess :-)

Functional but not very pretty IMHO. At least some struts can give the illusion that parts are fixed instead of magically floating.

Honestly, if we are going for realistically functioning helicopter rotor heads. Adding aesthetics can just reduce performance.

[Pds314]

12 minutes ago, Gman_builder said:

Honestly, if we are going for realistically functioning helicopter rotor heads. Adding aesthetics can just reduce performance.

Making it work reduces performance, it seems. The thing has no structural integrity under flight loads. Zero. It just wants to rip itself apart if it gets anywhere close.

[Gman_builder]

1 minute ago, Pds314 said:

Making it work reduces performance, it seems. The thing has no structural integrity under flight loads. Zero. It just wants to rip itself apart if it gets anywhere close.

I would assume that has to do with the use of all those low-crash-tolerance parts and the insane amount of moving parts on it.

But don't quote me on that....

[Pds314]

3 minutes ago, Gman_builder said:

I would assume that has to do with the use of all those low-crash-tolerance parts and the insane amount of moving parts on it.

But don't quote me on that....

It's not the crash tolerance. Nothing is crashing into anything at any significant velocity difference. The problem is wobble caused by it being composed of a dozen separate craft causing a self-sustaining wobble in the swashplate.