Tips for making STOCK electric/jet powered propellers for VTOL aircraft?

[Ol’ Musky Boi]

So someone recently challenged me to make a replica of the Quinjet from the Marvel Cinematic Universe. It is a cargo VTOL aircraft with a similar purpose to Boeing's V-22 Osprey.

I wanted to make my replica unique, so I decided to make some stock electric/jet powered propellors for the VTOL function. But I've never really delved into the world of stock propellers before. So I was wondering if any of you had any tips on building them, or which design would be most appropriate (are high TWR propellors even possible)? Preferably they need to be relatively low profile, although I acknowledge that I may have to lose some aesthetics for functionality. The design for the aircraft will probably use MK3 parts although I could switch to MK2 for lower mass.

Any help/criticism is welcome!

Edited August 2, 2018 by Ol’ Musky Boi

[Vanamonde]

How-to question moved to the how-to subforum. And good luck with your project. 

[Xd the great]

12 hours ago, Ol’ Musky Boi said:

So someone recently challenged me to make a replica of the Quinjet from the Marvel Cinematic Universe. It is a cargo VTOL aircraft with a similar purpose to Boeing's V-22 Osprey.

I wanted to make my replica unique, so I decided to make some stock electric/jet powered propellors for the VTOL function. But I've never really delved into the world of stock propellers before. So I was wondering if any of you had any tips on building them, or which design would be most appropriate (are high TWR propellors even possible)? Preferably they need to be relatively low profile, although I acknowledge that I may have to lose some aesthetics for functionality. The design for the aircraft will probably use MK3 parts although I could switch to MK2 for lower mass.

Any help/criticism is welcome!

There is a mod quizaerojet? That has the vtol wings.

[Ol’ Musky Boi]

13 minutes ago, Xd the great said:

There is a mod quizaerojet? That has the vtol wings.

Part of the criteria I set myself is to do it with all stock parts (my bad, I should've made that clearer in the title).

EDIT: Title has been corrected.

Edited August 2, 2018 by Ol’ Musky Boi

[Xd the great]

4 minutes ago, Ol’ Musky Boi said:

Part of the criteria I set myself is to do it with all stock parts (my bad, I should've made that clearer in the title).

EDIT: Title has been corrected.

Well, the fans are hard to do...

Still, build one. Then set the horizontal jet engines to 0 thrust limit for balance checking.

Use the CoM and CoT tracker.

Highly suggest using rcs for correction.

Flying too is a pain in the ***. Bring airbrakes to slow down midflight.

Use action groups for horizontal and vertical mode.

[Ol’ Musky Boi]

38 minutes ago, Xd the great said:

Well, the fans are hard to do...

Still, build one. Then set the horizontal jet engines to 0 thrust limit for balance checking.

Use the CoM and CoT tracker.

Highly suggest using rcs for correction.

Flying too is a pain in the ***. Bring airbrakes to slow down midflight.

Use action groups for horizontal and vertical mode.

Yep, RCS is a must, as are airbrakes and action groups. And I am using the mod "RCS build aid" for working out CoM CoT and the dry CoM (great mod, tells you exactly where your engines should be).

So far I've experimented with a couple of designs, this one in particular has a very low profile (as stock propellors go) but I did have to clip ~10 small reaction wheels together, which felt a bit cheaty. It also needs some refining as it didn't even have a TWR of 1, but it was a very stable design that didn't break easily (I think the problem was that the rotor shaft was too heavy and so it couldn't spin fast enough. I'll try putting the landing gear on the tube itself.)

I also built this one, which is basically a design I copied from this youtube video: https://www.youtube.com/watch?v=lrVKFKRDFm8 and uses the traditional "RCS in a thermometer cup" design for the hinge. Although it had the highest TWR of the two designs it did have some stability issues if left to run for more than a few seconds.

I'll post updates on any new designs I try but for now thats it.

(I'm still considering turboprops as an option, but I am yet to build a successful one).

Edited August 2, 2018 by Ol’ Musky Boi

[Xd the great]

You might as well clip goliah turbofans or other engines.

[Ol’ Musky Boi]

Just now, Xd the great said:

You might as well clip goliah turbofans or other engines.

But that wouldn't be as cool, would it? 

[Xd the great]

8 minutes ago, Ol’ Musky Boi said:

But that wouldn't be as cool, would it? 

You can choose to build one that looks like, or one that can fly.

[Ol’ Musky Boi]

4 minutes ago, Xd the great said:

You can choose to build one that looks like, or one that can fly.

No need to be so pessimistic. Besides, I know it is possible because it has been done before: 

All stock, no mods. Anything can fly with enough POWAH!

Edited August 2, 2018 by Ol’ Musky Boi

[Xd the great]

1 hour ago, Ol’ Musky Boi said:

No need to be so pessimistic. Besides, I know it is possible because it has been done before: 

All stock, no mods. Anything can fly with enough POWAH!

How do you actually make stock propellers...

[Ol’ Musky Boi]

Its not too hard if you know what you're doing, I found this video to be a pretty good guide: 

 

[mystifeid]

54 minutes ago, Ol’ Musky Boi said:

Its not too hard if you know what you're doing, I found this video to be a pretty good guide: 

I think that might be @SuperHappySquid's video. Maybe he can give you some tips. There are also a lot more prop videos on his channel - https://www.youtube.com/user/SuperHappySquid/videos

[Ol’ Musky Boi]

4 minutes ago, mystifeid said:

I think that might be @SuperHappySquid's video. Maybe he can give you some tips. There are also a lot more prop videos on his channel - https://www.youtube.com/user/SuperHappySquid/videos

Ahh thanks, I was going to mention him but I did not know his name on the forums. 

[Ol’ Musky Boi]

Ok, I think I've got a pretty stable design now. I've decided on a hybrid electric/jet propeller design, the propeller will provide the majority of the VTOL power, and the jet engine will allow me to control the thrust much more easily (rather than switching between the two propellers). I used a structural fuselage to house the reaction wheels, stay-putniks and RTGs, and the propeller has 8 blades (mainly for visual effects). I'm thinking about using the structural tubes from the new DLC to build a shroud around the blades as well...

Each Prop produces over 10KN of thrust! (jet engines not included)

Now, onto the aircraft design!

Edited August 2, 2018 by Ol’ Musky Boi

[Ol’ Musky Boi]

 

Ta da! This is just a prototype, and it still needs a lot of refinement to increase ease-of-use. But it works! and as you can see, the two jet engines only provide 85% of the thrust needed to take off, the next 15% is pure electric POWAH! (You may notice I switched from using wheesleys to panthers, wheeslys weren't prouducing enough thrust for VTOL.)

The next thing on my to-do list is to stop the propellors exploding (any suggestions there?), then to fix any bugs with horizontal flight. Then the FUN parts, I'm talking a motorbike in the cargo bay, stock missiles under the wings, and perhaps an aircraft carrier to land it on... 

I'll post the craft file when I'm satisfied with the design.

[Ol’ Musky Boi]

I'm having a bit of a bug. KSP is saying that when the props explode, it is because they have collided with the MK3 cargo bay. But they are nowhere near each other! It's a little frustrating, I kinda wanted this to fly with no cheats enabled. Any suggestions?

[bewing]

I'd need the craft file now, but it sounds like a bug.

 

[Ol’ Musky Boi]

1 minute ago, bewing said:

I'd need the craft file now, but it sounds like a bug.

 

I think the problem is the engine, the nose cone tends to wobble too much. I'm making modifications as we speak.

[Ol’ Musky Boi]

14 minutes ago, bewing said:

I'd need the craft file now, but it sounds like a bug.

 

Nope, definitely not the engines. Here's the craft file on Google Drive if you need it: https://drive.google.com/open?id=1T2wK7lEPVxK8wFw7dV5sVR7N96-OCXrx

[OHara]

11 hours ago, Ol’ Musky Boi said:

I'm having a bit of a bug. KSP is saying that when the props explode, it is because they have collided with the MK3 cargo bay.

If it is always the starboard prop,  and the reported collision is with the MK3 ramp, you might be running into a bug in version 1.4.x.  That version updated the game engine, which people notice when pushing the physics engine with things like props.  I still use version 1.3.1 for these things (and wherever you bought KSP there should be a way to chose which version(s) to install for yourself).  Your props are still somewhat wobbly, and props do fall apart when they wobble faster than the physics engine can keep up, so maybe they are breaking on their own and falling into the MK3 cargo ramp.

There are less wobbly bearings that you might like to try; you can find them in the spacecraft-exchange threads about propeller craft.

Generally, you seem to have KSP propellers figured out.  You scaled the blades so they spin near 40 radians/sec (2200°/s) which gets the most out of the reaction wheels without hitting the physics-simulator limit of 50 rad/sec.  You can easily get TWR>1 on pure electric-prop craft, but KSP engines are heavy so they will have to lift themselves and their fuel.

Edited August 3, 2018 by OHara

[Ol’ Musky Boi]

6 hours ago, OHara said:

If it is always the starboard prop,  and the reported collision is with the MK3 ramp, you might be running into a bug in version 1.4.x.  That version updated the game engine, which people notice when pushing the physics engine with things like props.  I still use version 1.3.1 for these things (and wherever you bought KSP there should be a way to chose which version(s) to install for yourself).  Your props are still somewhat wobbly, and props do fall apart when they wobble faster than the physics engine can keep up, so maybe they are breaking on their own and falling into the MK3 cargo ramp.

There are less wobbly bearings that you might like to try; you can find them in the spacecraft-exchange threads about propeller craft.

Generally, you seem to have KSP propellers figured out.  You scaled the blades so they spin near 40 radians/sec (2200°/s) which gets the most out of the reaction wheels without hitting the physics-simulator limit of 50 rad/sec.  You can easily get TWR>1 on pure electric-prop craft, but KSP engines are heavy so they will have to lift themselves and their fuel.

Thanks for the tips, I'll try redesigning the props with a more stable bearing, and see where it goes from there. If I can increase thrust significantly then maybe I could downgrade the engines, but I doubt it.

[Ol’ Musky Boi]

Steam link: https://steamcommunity.com/sharedfiles/filedetails/?id=1470890638&searchtext=

So here it is, although my propeller powered version worked, it was not reliable. So I compromised and built a jet-powered version whilst I continue development of a stable turboprop. I was going to give up, but after seeing Stratzenblitz75 sending a stock helicarrier TO LAYTHE I had renewed hope. That version should be done in a week (I am a bit of a perfectionist...)