Stock propeller help?

[justmeman117]

I'm mostly asking for help in this thread. I'm currently trying to develop vehicles I can deploy permanently in the field to support a career mode colonization effort. This means I need to set up mining facilities, SSTOs, and small towns on every planet.

 

Perhaps the most difficult planet to set up such a colony with reusable technologies on is Eve. Thanks to its dense atmosphere, simply using aircraft to fly at faster than driving speeds between bases is a compelling option. However, jet engines obviously don't work inside Eve's atmosphere. So, I have to resort to stock electric propellers (unless I want gas guzzling rocket planes that are mostly fuel, and need to land and refuel multiple times in one trip).

My difficulty is prototyping a stock electric propeller with the specifications I want. I wanted to make one out of .625 meter parts, to push the size and mass limits of stock propellers (and then scale up from there for larger planes). This means using .625 reaction wheels, and possibly using .625 meter decouplers in some manner as the bearings. Next, the prop needs to be able to redock to the mothership, since propellers tend to break easily whenever the game loads or unloads a vehicle with a propeller. And finally, the propeller needs to be a sub-assembly with a docking port, so that I can change out a broken engine in the field if I need to. No sense in condemning an aircraft I went through the trouble of getting to Eve if all that broke is the propeller.

Anyway, I haven't had too much luck, a whole lot of friction between parts, and the prop breaking free of the different kinds of bearings I've designed. So I thought I'd turn to the KSP community for tips or tricks on designing props that aren't just for show, but are actually useful and utilitarian. The ability to redock is probably the part I care most about.

I also have the making history pack, so I have those parts to draw from for making props as well. The structural tubes might be useful for 1.25 meter props and up.

 

Attached is a picture of one of my failed designs strapped to a small helicopter fuselage. The bearings are made out of antennae and .625 decouplers. It has too much friction, and breaks easily.

Edited March 29, 2018 by justmeman117

[HolidayTheLeek]

I don't have the making history DLC, but I could certainly help out with propellers.

For smaller propellers (0.625m) I'd recommend the RCS ball bearing. It's currently one of the best out there.

I'm not the best at explaining things, but if you want, I could give some craft files of propeller designs I use in my own craft. (I don't know if they work in helicopters though)

If possible, I could examine your craft and hopefully you'll get some working aircraft/helicopters for eve

 

[HalcyonSon]

9 hours ago, HolidayTheLeek said:

I don't have the making history DLC, but I could certainly help out with propellers.

For smaller propellers (0.625m) I'd recommend the RCS ball bearing. It's currently one of the best out there.

I'm not the best at explaining things, but if you want, I could give some craft files of propeller designs I use in my own craft. (I don't know if they work in helicopters though)

If possible, I could examine your craft and hopefully you'll get some working aircraft/helicopters for eve

I've seen (between the forum and youtube vids) three main styles of bearings (Stayputnik / Fairing, Stayputnik / Structural Fuselage, and RCS  ball / Thermometer).  Smaller hinges (not motors) use Antennae and Thermometers.  My attempts at the Stayputnik / Structural Fuselage / Fairing were less successful than my designs with the RCS ball and Thermometers.  It's fairly sturdy and reasonably low friction as long as the clearances are just right.  I have a single OKTO2 probe core attached to ten 0.625m Reaction Wheels with four 400 EC batteries on the rotor, and use a 1.25m fairing and 1.25m : 0.625m adapter on either end of the housing.  I use 8x symmetry and overlap the RCS balls on either end of the rotor, then cage them in 8x symmetry thermometers on each end of the housing with the propeller and nose cone offset from the end of the rotor to outside the housing.  A 0.625 m decoupler holds the rotor to the housing on load-in, and is offset so it blows clear of the motor after staging.

I can tell you right now, that docking port won't reattach.  You need about two meters straight out (maybe more) before they'll reset and reattach to the same port.  I'm testing a docking port between the side of the rotor and the inside of the housing now, but haven't got it sorted.

If you haven't played with it yet, Bon Voyage is a great mod for rovers.  It lets them traverse in the background so you don't have to constantly reload or repair blown wheels.

Edited March 29, 2018 by HalcyonSon

[EpicSpaceTroll139]

Like HalcyonSon mentioned, the docking port probably won't reattach without doing something like quicksave+quickload, which risks breaking the bearings before they dock. What I've started doing, when possible, is to use a claw placed close enough to the rotating part that when armed it will immediately grab it, but far enough away that when disarmed it will not stop it from rotating.

I should also mention that bearings using the decoupler itself as a sleeve will not work, as the decoupler is not hollow like it appears.

In the past I used a bearing that had an antenna "pin" spinning inside a hole in a disk of 5 or more of the small static solar panels, but I'm starting to experiment with linear RCS port bearings, since KSP 1.4 broke literally all of my helicopters.

You can find bearings of all shapes and sizes in these threads:

 

[HalcyonSon]

Got it!  I'm justifying the external docking ports as cooling fan exhausts.  I tried to tuck them inside the fairing, but everything slings out when it starts spinning, so the rotor ports have to be outside the housing ports. 

 

You can see the decoupler and fairing lying around on the runway.  Launch clamps work MUCH better than wheel brakes for testing. 

 

 

 

Edited March 30, 2018 by HalcyonSon

[HalcyonSon]

Bearing details.  All those joints can get a bit wiggly, and it doesn't take much for the rotor to get cockeyed and pop the RCS ball outside the Thermometers.  I've tried rebuilding it with an I-beam down the middle and struts holding the end reaction wheel to the I-beam, but it was even more wiggly than before.

Edited March 30, 2018 by HalcyonSon

[justmeman117]

Thank you everyone for the help.

 

Holiday, any craft files would be greatly appreciated. I’ve experimented recently with RCS and thermos, but it kept coming loose. I think it’s because the thermos were facing the wrong way. I also have a few craft files already with working bearings, but they’re difficult to reverse engineer since the propeller is often built right into the aircraft. It’s one of the reasons why I wanted to develop one as a sub assembly, so I can easily do engine changes in the field if one breaks.

 

Halcyon, I noticed that about the docking ports. I thought about experimenting with side facing docking ports, but it’d make the assembly much wider. I also had this idea of making bearings that could slide up and down. That way, when in use ports move away from each other, and when you shut it down, you can use RCS to push them back together again. I’ll have to play around with how far they need to move before it resets though. I might also be able to just straight up change the part file so it resets at a closer distance. Also, thanks for the tip on the mod, I might just use that instead for Eve and Duna. I might still need props for Eve thanks to its oceans, but they’ll be fewer and farther between.

Also, that’s an awesome design. It’s not .625 meter, so it’ll be harder to airlift places inside cargo bays, but motors that small are pushing what’s possible. That design would be useful for larger aircraft in places like eve. Would you mind sending me the craft file?

 

Epic, I have yet to try out the claw for this, but I have plans to make my 1.25 meter versions use it. Also, while finicky, the decouplers can work. While they don’t have the clearance the part would lead you to believe it has looking at it, it does have a small hole in the middle about wide enough for a cubic to fit in there. I got the idea to use them for bearings after I had some positive experiments using them as a tow hook for rovers and aircraft. I have an ultralight with folding wings that uses bearings based on decouplers. That being said, I learned the hard way they aren’t the best approach for high speed bearings. They cause too much friction depending on what I use as the shaft, and while I’ve gotten airborn with this helicopter, too much movement in the fuselage causes the shaft to break free. It seems they’re best for slower applications like doors. I’ll have to check out those threads, and see what techniques they use.

Edited March 30, 2018 by justmeman117

[selfish_meme]

A lot of us got inspiration from this guy it's an RCS/RCS bearing, though many have thrown other things in the mix

https://kerbalx.com/quitessa/Ultrasmooth-Microbearing

Like this, same principle, larger parts

https://kerbalx.com/SelfishMeme/KAe-Stock-Turboprop-Cargo-Plane---new-bearing

[Andetch]

When I make a stock prop - which I haven't got one to work as it should yet, but I have got the making the bearing part pretty sorted, I just use a structural fuselage because it is hollow, and put small wheels (the tail dragger wheel) onto narrow (.625m) empty fuel tanks to create a smooth working part! Place some place anywhere rcs thrusters to create  some ball bearing style parts between the spinning core and the rest of the craft, and you're away!

[Azimech]

2 hours ago, Andetch said:

When I make a stock prop - which I haven't got one to work as it should yet, but I have got the making the bearing part pretty sorted, I just use a structural fuselage because it is hollow, and put small wheels (the tail dragger wheel) onto narrow (.625m) empty fuel tanks to create a smooth working part! Place some place anywhere rcs thrusters to create  some ball bearing style parts between the spinning core and the rest of the craft, and you're away!

This kind of setup is something we did in the old days (KSP 1.0). It has since fallen out of grace due to vibrations and reliability issues.

[Andetch]

Managed to get over vibration issues with suspension settings and a "cap" on either end.

[Azimech]

4 minutes ago, Andetch said:

Managed to get over vibration issues with suspension settings and a "cap" on either end.

I must admit, suspensions have improved since v1.0.

[Andetch]

I didn't start playing until 1.1 or 1.2 I think...

[selfish_meme]

One of the most useful tools to make stock bearings is the mod collide-o-scope, it shows the wireframe colliders

[HolidayTheLeek]

I see you're trying to use docking ports to redock the props. Good job on getting it working! Personally, I've had better experience using claws. They're bulkier, but they tend to be more reliable for me.

[qzgy]

On 3/29/2018 at 5:51 PM, EpicSpaceTroll139 said:

I should also mention that bearings using the decoupler itself as a sleeve will not work, as the decoupler is not hollow like it appears.

As of 1.4, I believe this information is false, as they've updated the decoupler colliders to have a hollow section. Not much and square but still hollow.

As for docking ports - I'm pretty sure they need to be moved a distance before it can reattach....

[HalcyonSon]

On 3/29/2018 at 11:04 PM, justmeman117 said:

Halcyon, I noticed that about the docking ports. I thought about experimenting with side facing docking ports, but it’d make the assembly much wider. I also had this idea of making bearings that could slide up and down. That way, when in use ports move away from each other, and when you shut it down, you can use RCS to push them back together again. I’ll have to play around with how far they need to move before it resets though. I might also be able to just straight up change the part file so it resets at a closer distance. Also, thanks for the tip on the mod, I might just use that instead for Eve and Duna. I might still need props for Eve thanks to its oceans, but they’ll be fewer and farther between.

Also, that’s an awesome design. It’s not .625 meter, so it’ll be harder to airlift places inside cargo bays, but motors that small are pushing what’s possible. That design would be useful for larger aircraft in places like eve. Would you mind sending me the craft file?

My design can probably be shrunk to 0.625 m with some creative offsets.  I happen to be using the 1.25 m inline fuselage as the root for my plane, and I want a fairing to minimize drag, but all the critical components are smaller.  You could use a 200 EC 0.625 m battery inline, slip an RTG down the middle, then move the docking ports till the housing ports overlap in the middle with an octostrut capping the bearing...  Shoot, I might play with that idea tonight.  I'll have to look into sending the craft files, maybe post them on KerbalX.

I'm currently working on a turboprop that fits into a 1.25 m fairing.  Most of them are much larger, with a much higher part count than I like to deal with.  It seems to take a lot more fiddling to get a turboprop working than it does an electroprop.  My 2 and 4 Juno designs go faster AFTER the prop has burned and smashed to little pieces than they do when operating as intended.

[Azimech]

24 minutes ago, HalcyonSon said:

 

I'm currently working on a turboprop that fits into a 1.25 m fairing.  Most of them are much larger, with a much higher part count than I like to deal with.  It seems to take a lot more fiddling to get a turboprop working than it does an electroprop.  My 2 and 4 Juno designs go faster AFTER the prop has burned and smashed to little pieces than they do when operating as intended.

Yes, they have quite the learning curve. If you need help, send me PM.

[HalcyonSon]

1 hour ago, Azimech said:

Yes, they have quite the learning curve. If you need help, send me PM.

I appreciate the offer.  Your designs look elegant, but very very large.  I've been looking at erasmusguy's stuff too.  I tried out his eg02, but that thing has a nasty roll on a plane as small as what I've been testing.  His outer solar panel rotor is interesting, but lacks punch when it's scaled down.

I have a few ideas I'm toying with.  It seems that compact engines are even more difficult to make effective than large ones, so I'm trying to combine small slick bearings with multiple types of rotor vane.  Also testing different ways to negate or occlude the jet thrust to prevent  roll.  I thought fairings would work for that, but they really don't.  I pushed a plane right off the runway with a pair of junos pointed sideways in a closed fairing.  A service bay might do the trick, but that's a very very small space to work with, and I'm not even sure the jets will start in a closed service bay.

[sevenperforce]

Docking ports must move 5 meters apart before they can redock.

Unless you quicksave and quickload, which resets the redock.

[selfish_meme]

This one was built on quitessa's bearing, to fit 1.25, it alleviated the nasty torque by using contra-rotating props, it used docking ports to release the bearing, but you could not redock.

Unless you get the mod recoupler

Edited April 3, 2018 by selfish_meme

[Lego_Prodigy]

I would love a simple design that can be readjusted for things such as submarine usage.

[selfish_meme]

6 minutes ago, Lego_Prodigy said:

I would love a simple design that can be readjusted for things such as submarine usage.

I built one, but it is just for show, you need a pretty hefty blade to get any speed underwater, which means a lot of force to move it.

https://kerbalx.com/SelfishMeme/KAe-Deep-Sea-Vehicle

[HalcyonSon]

Motor testing continues apace... with lots of lost bits and explosions.  You know, typical Kerbal fashion.  All-RCS ball bearings don't seem to be quite as stable as RCS/thermo bearings.  The 0.625 m motor fits neatly into a 2.5m service bay or Mk 2 cargo bay, but the propeller blades stick out.  It might be possible to place the propellers on docking ports, though I'm not sure what kind of ground equipment you'd need to replace a prop.  I'll play with it more tonight and try to get something on KerbalX.

 

Edited April 3, 2018 by HalcyonSon

[HalcyonSon]

Finally got the 0.625 m design working right.  Gave up on new bearing designs with reduced part counts and went with what worked on the 1.25 m design.  The motors themselves easily fit into a Mk 2 Cargo Bay or 2.5 m Service Bay, but the props stick out.  Still working to make the rotors mate back to the housing and make the prop blades detachable.

https://kerbalx.com/HalcyonSon/Electroprop-sm-1

Edited April 4, 2018 by HalcyonSon