Has anyone made a decent compact electric prop from the rotors yet?

[Lord Aurelius]

Leading up to this release there were rumors that Squad would FINALLY be adding an electric propeller, but sadly we didn't get one.

 

However, using the new rotors I was able to make a decent large prop (made a large quadrotor), but I'm having trouble making a compact one with the small rotor due to the lack of small aerodynamic surfaces.

 

Has anyone come up with a working small (~1.25m diameter) prop with the new parts? The ones I tried to put together with the smallest elevons and fins could barely pull a tiny plane along the ground at 4 m/s.

[KerikBalm]

Best Ive seen is 50 m/s. My helicopters only get about 20 m/s.

At least I can fit them in a mk3 bay...

[fourfa]

I get about 85m/s from a twin-nacelle, quad-motor (only ~50m/s as a twin/twin). Prop circle diameter is larger than 1.25m if that’s the question...  I will agree with everyone that this is a really ugly solution, but unless you build kerbally storks that sit meters above the runway I can't find haven't found a better way.

https://kerbalx.com/fourfa/Kessna-Twin

lack of appropriate aero surfaces is a serious limitation here. Has anyone played with panels for props yet?

The problems with small diameter props are going to drive me toward tilt-rotor work, I think.

Edited May 31, 2019 by fourfa

[TheTripleAce3]

I tried but the torque is murder

[Lord Aurelius]

41 minutes ago, TheTripleAce3 said:

I tried but the torque is murder

Yeah, I noticed that as well, will probably need to go with dual engines with counter rotating props in most of my designs.

[TheTripleAce3]

1 minute ago, Lord Aurelius said:

Yeah, I noticed that as well, will probably need to go with dual engines with counter rotating props in most of my designs.

I tried a tandem engine (do-335 style) and it was not a happy bird at all

[Lord Aurelius]

2 hours ago, fourfa said:

I get about 85m/s from a twin-nacelle, quad-motor (only ~50m/s as a twin/twin). Prop circle diameter is larger than 1.25m if that’s the question...  I will agree with everyone that this is a really ugly solution, but unless you build kerbally storks that sit meters above the runway I can't find haven't found a better way.

https://kerbalx.com/fourfa/Kessna-Twin

lack of appropriate aero surfaces is a serious limitation here. Has anyone played with panels for props yet?

The problems with small diameter props are going to drive me toward tilt-rotor work, I think.

I think that prop design will actually work for what I'm trying to do (build a solar-powered aircraft to send to Eve).

Next will be a nuclear powered aircraft for Jool with that thick atmosphere to carry the weight.

4 minutes ago, TheTripleAce3 said:

I tried a tandem engine (do-335 style) and it was not a happy bird at all

I was thinking more of like the aircraft @fourfa shared with both engines facing the same way, seems less likely to kraken out with the startup torque

Edited June 1, 2019 by Lord Aurelius

[fourfa]

Update.  Here's what I've found so far regarding prop angle.  I spent the evening playing with a big Mk3 twin-1.25m-nacelle cargo plane with servo-controlled prop blade pitch.  So start with blades at 0 degrees, with no angle of attack relative to their rotation, and thus no lift.  Anywhere from 30-45 will give a ton of bite and lots of acceleration at launch, but quickly hit a max speed in the air of ~50m/s.  60 degrees is good up to about 85m/s (this is what's on my little twin above).  I could get to above 100m/s with a max pitch of 80 degrees - more than that starts to slow down.  

I changed the Kessna Twin from 60 to 75 on both sides, and top speed went from 85m/s to 110m/s with no other changes.  Rollout is real slow, with a massive boost in thrust at ~20m/s on the runway.  Variable pitch is the way to go if you can afford it - the little 0.625m stacks probably can't?

I'm also testing the thesis that if you're not routinely at or close to the max RPM (460 for the M and L motors), you're experiencing more drag for equal thrust.  Going to play with numBlades for a while looking for higher RPMs and more speed.

So far, I've not had any luck with timewarp.  Even with an ugly external strut to the front of my motor stacks, they wobble to death in 2x.

Edited June 1, 2019 by fourfa

[KerikBalm]

Its a shame that these so far aren't working out as well as old stock props... I was expecting something at least this good:

That was on Duna, modded to have 25% higher surface gravity (0.376 G: mars' gravity)... but still

I've found blade pitch is very important the faster you go, the more you want them to be closer to perpendicular to the direction of travel.

The old way allowed smoothly varying prop pitch, but I'm having some symmetry problems, and I have to action group the blade pitch change.

Still just barely pushing 50 m/s

As far as compact, here's what I was developing to try to make a helicopter that I can deploy from a mk3 bay... I was going to give it wheels, or make a crane to load and unload it:

but it doesn't fly all that well, I think a rover would be faster... except in very mountainous terrain

[headdie]

I made a Chinook style twin rotor helo,

you absolutely need something to counter torque so remember to set one rotor to rotate in the opposite direction

I also included a control unit with SAS and a reaction wheel to aid with stability and steering

Hinges under the motors act as the collective bound in my case to the pitch controls

Motor RPM bound to Axis Group 1 which is bound to the same keys as throttle up and down

Main issue with this version is I get a right hand turn/drift when pitching forwards

Used small / high rpm motors

https://kerbalx.com/headdie/Rotocopter-2

Edited June 1, 2019 by headdie
Portions Redacted by Moderator

[Gargamel]

1 hour ago, headdie said:

[snip]

Please use Kerbalx.com or another file hosting service when posting craft files or other large files.  Large walls of text, even in a spoiler block, can cause issues for some users. 

[headdie]

18 minutes ago, Gargamel said:

Please use Kerbalx.com or another file hosting service when posting craft files or other large files.  Large walls of text, even in a spoiler block, can cause issues for some users. 

ok, sorry about that

[ghosteh]

Hello, i've made several propeller aircraft with the new rotors, they're quite good in my opinion.

I've made a C-130 with them and a light civilian craft. The C-130 tops out at around 140m/s with 4 propellers with 2 motors on each engine, its nearly 60 tonnes. The light craft, which I have released and you can find here, is 4.5 tonnes and flies at about 130 m/s with 2 engines and 2 motors per engine. Here's photos of the aforementioned light craft and C-130 flying:

Spoiler

I might release the C-130, but currently it has an issue of leaning right when using the elevators and I cannot find the cause.

Edited June 2, 2019 by ghosteh
spoiler