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

[Pds314]

 

82 rads/s! And it lived!

For the record, that's more than half a rotation.. PER PHYSICS TICK.

 

Edited July 15, 2016 by Pds314

[Pds314]

THIS IS YOUR PROP.


THIS IS YOUR PROP ON DRUGS:


For real though, my design goals:

18+ blowers. check! 18, easily expandable up to ~54
 
Under 80 parts: check! 54 without prop or intakes!

Under 6 tonnes: check! 5425 kg!

High reliability: check. Nothing should be able to spin a prop that is in some kind of bizzare stable vibration like that, and I don't even have a clue what the aerodynamics thinks of it.Nonetheless, the engine can reliably hold the vibrating prop at 50 rad/s without issue.

50 Rads/s or close. CHECK. The engine becomes unstable (i.e. prone to sudden loss of speed, not usually explosions) past 85 rads/s, making it far and away the fastest-spinning engine ever. The fastest snapshot of it I have is about 100 rad/s, and it survived.

Blowers and prop only non-symmetrical items: check.

Now to figure out how to make an 80-rad/s capable prop...

Edited July 15, 2016 by Pds314

[Pds314]

Hmm.. Maybe I could design it to only reach such high speeds once the vehicle is at speed..

[Azimech]

4 hours ago, sdj64 said:

Lots of science going on here!  I figured I'd share my newest and biggest engine, it is Mk3 size with 24 blowers.  It uses the lowest part count bearing ever at a whopping 4 parts - 2x stayputnik inside structural fuselages.  I'm not sure how good the performance is - I got it going about 165 m/s steadily but it seems like the bearing has high friction.  KER says around 30 degrees per second at that speed?  I think it just has the wrong unit, but 30 rads/s seems high.  I count around 3-4 rotations per second which is about 20 rad/s.

It is a reliable proof of concept for a large engine with a wheelless bearing though.

I think I will try a 2.5m engine using a couple of service bays next.

Last time I checked KER is unreliable for reading angular velocity.

3 hours ago, Pds314 said:

 

82 rads/s! And it lived!

For the record, that's more than half a rotation.. PER PHYSICS TICK.

 

Did you change a setting? Please tell us!

[Pds314]

8 minutes ago, Azimech said:

Last time I checked KER is unreliable for reading angular velocity.

Did you change a setting? Please tell us!

Nope. No settings changed. The thing actually sustains ludicrous speeds. The problem currently is that no prop I've put on it can handle 60 rad/s. They either flail wildly, rip off, or expand so large they don't work, or potentially, for 2- bladed props, collide with the engine housing. That six-bladed small prop seemed to become a bizarre sort of flailing oscillator that could somehow hold the turn rate at 50 rad/s by bleeding off huge amounts of energy. Whether that translates to crazy thrust, drag, vibration, or damping is anyone's guess.

Edited July 15, 2016 by Pds314

[Azimech]

4 minutes ago, Pds314 said:

Nope. No settings changed. The thing actually sustains ludicrous speeds. The problem currently is that no prop I've put on it can handle 60 rad/s. They either flail wildly, rip off, or expand so large they don't work, or potentially, for 2- bladed props, collide with the engine housing.

Meanwhile I've got different problems.

 

 

What are your pc specs?

[Pds314]

14 minutes ago, Azimech said:

Meanwhile I've got different problems.

 

 

What are your pc specs?

Laptop from 2013. i7 4700mq, 16 GB ddr3 1600. Geforce 770m.

That looks a lot like a less severe version of what's happening to my props.

Edited July 15, 2016 by Pds314

[Gman_builder]

@Pds314I am beyond impressed. Please! Teach us your ways! I have hardly broken the 45 rad/s mark! 

Edited July 15, 2016 by Gman_builder

[Pds314]

19 minutes ago, Gman_builder said:

@Pds314Your planes are all amazing! You should make replica prop planes. As your engines are very low part count and high performance. Maybe start with a simple one, like a Lockheed Constellation!!  

I may replicate that plane. First, however, I want to make a hyperspeed prop to put on my hyperspeed engine.

[Gman_builder]

20 minutes ago, Pds314 said:

I may replicate that plane. First, however, I want to make a hyperspeed prop to put on my hyperspeed engine.

Ya that's cool. I am still unable to test anything though. There is definitely something wrong with my computer. I just did another fresh install with 0 mods and I get 5 FPS with the Aeris 3A which is only a 18 parts plane with 1 engine. FUUUUUUU my life.

[Pds314]

26 minutes ago, Gman_builder said:

Ya that's cool. I am still unable to test anything though. There is definitely something wrong with my computer. I just did another fresh install with 0 mods and I get 5 FPS with the Aeris 3A which is only a 18 parts plane with 1 engine. FUUUUUUU my life.

Look at the stock settings. Is the lighting count thru the roof?

[Pds314]

Wow. This has got to be the most thrown-together plane ever. Literally take a test cart. Slap wings on it. You now have an adequate prop test aircraft.


Pity exceeding the prop's RPM limit cause it to wobble and break things.



List of failure modes discovered:

#1. Prop-collapse: The prop expands as it approaches 50 rad/s. Somewhere between 50 and 60, it turns into a messy oscillating thing. This is stable statically, but not during acceleration. This violently collapses, causing the shaft to rip out.

#2. Unexplained: The shaft is in two pieces for some reason. One piece rapidly increases in speed several times. Up to 165 rads/s in one screenshot.

#3. Prop collision: prop encounters something while bending wildly. Boom.

[Gman_builder]

I got my game to work by restarting my computer 11 times. I was testing my engine and the prop came off and all the blowers exploded. But the shaft maintained 50 rad/s by it's own accord and was extremely stable while doing so. I have no idea if I can reproduce this effect but I wonder if it can be exploited.

 

[Pds314]

Wow... two basic fins.. TWO BASIC FINS whether strutted together or not... are somehow capable of completely eliminating the entire torque of the engine simply by expanding. Even at a very shallow pitch.

I'm coming to believe that adding more and more power will just make the props get bigger and bigger or perhaps with more complex props, change modes of oscillation. I.e. 5% throttle = 51 rad/s flailing a little bit. 100% throttle = 51 rads per second flailing like mad.

Is it cheating to toggle physics significance of the part you want to make the prop out of?

I guess the alternative is to ensure that the prop somehow generates enough inwards force to keep stable, if that would even work.

Let's see. At 50 rads/s, a prop 6 meters out is moving 300 meters per second. hmm.. that could be an issue.

Edited July 15, 2016 by Pds314

[Pds314]

A few hours ago, I thought I was going to be making 100 rad/s props in no time. Now, I have my doubts that anything over 51 can be stabilized. Still, I suppose being able to press into the 51 rads/limit is somewhat useful, and, if done correctly, the blade expansion might be possible to exploit for extra lift. The real problem is power, since an engine at 80 rads/s is much more powerful than one at 50, but if it can't turn a prop, then I'm left hoping for some sort of high speed gearing or prop- containment device or something...

Hmm... I wonder if atmospheric fluid spectrovariometers or other physicsless parts can be used to form a spinning cage to hold the prop in?

Edited July 15, 2016 by Pds314

[Gman_builder]

22 minutes ago, Pds314 said:

A few hours ago, I thought I was going to be making 100 rad/s props in no time. Now, I have my doubts that anything over 51 can be stabilized. Still, I suppose being able to press into the 51 rads/limit is somewhat useful, and, if done correctly, the blade expansion might be possible to exploit for extra lift. The real problem is power, since an engine at 80 rads/s is much more powerful than one at 50, but if it can't turn a prop, then I'm left hoping for some sort of high speed gearing or prop- containment device or something...

Hmm... I wonder if atmospheric fluid spectrovariometers or other physicsless parts can be used to form a spinning cage to hold the prop in?

I'm not quite sure I understand the downsides of having a expanding prop and how do you "engineer" a new prop? Like, what kind of engineering goes into it? I usually just operate on trial and error to get somewhere rather than math and science so your method isn't quite clicking with me.

[Pds314]

10 hours ago, Gman_builder said:

I'm not quite sure I understand the downsides of having a expanding prop and how do you "engineer" a new prop? Like, what kind of engineering goes into it? I usually just operate on trial and error to get somewhere rather than math and science so your method isn't quite clicking with me.

Same with me. I normally just throw together a new prop based on educated guesses. But with hyperspeed props, I think I can't keep doing that. Assuming hyperspeed props are even possible, they must somehow contain themselves, otherwise they always expand sufficiently large to keep the engine from revving past 51 rads/s.

[Gman_builder]

29 minutes ago, Pds314 said:

Same with me. I normally just throw together a new prop based on educated guesses. But with hyperspeed props, I think I can't keep doing that. Assuming hyperspeed props are even possible, they must somehow contain themselves, otherwise they always expand sufficiently large to keep the engine from revving past 51 rads/s.

How does the expanding negatively affect the engine's performance? Does it cause drag?

[Pds314]

2 hours ago, Gman_builder said:

How does the expanding negatively affect the engine's performance? Does it cause drag?

No. It reduces engine RPM and therefore power output. An expanded prop operating at 50 rads/s will have the same torque on it as an unexpanded prop operating at the same speed, meaning it generates no more lift. Try lifting a 10 kg weight? Now try lifting the same weight on the end of a 10-foot poll?

A large prop is like the 10 foot poll. It has high speed of travel through the air, but very little force. A small prop is like not having a 10-foot poll. It can have huge amounts of force from relatively small torque, but at relatively low speed.


Basically, expanding a prop causes the airflow over the prop to increase, which is good.

But it causes the force the engine can exert on the prop to decrease, which is bad.

Normally, these factors balance out, and so at high speeds, props getting good L/D and not generating excess drag get the same thrust.

But for engines like ours, where power output is directly linked to prop RPM, limiting prop RPM severely limits power output. What this manifests as is that you get the speed you would at much higher rpm, but you must reduce the blade pitch.

This is why you shouldn't put, for ex, an 8-bladed big prop on a 2-blower mk1 engine with a high max RPM. You won't be able to reach the design rpm, thus, you'll never be able to reach good performance due to excessive torque loss due to induced drag.

In other words, it isn't that a big prop is worse than a small prop at the same rpm, but that it prevents reaching higher RPM. In this case, as the prop gets bigger, the engine cannot get faster, and if there is an excess of torque, it simply widens the prop and gives it more leverage to hold back the engine. It wouldn't matter if you had 2-dozen panthers at full AB, the prop would not turn any faster, and thus, at high speeds, would not generate any more thrust.

One possible solution is to design light and efficient gearing using physicsless parts to change 80 rad/s and 18 Junos worth of torque into, say, 50 rads/s and 30 Junos worth. The problem is that most gearing systems I've built are wildly inefficient and fail before reaching 25 rads/s, let alone 80 or 50. Also, the gearing system would eat up part count and mass, making it of questionable benefit over simply adding more blowers. Considering it would not be hard to mod my current engine to have 36, or even 54 blowers, I'm not sure there's a whole lot of benefit to complex gearing systems.

Edited July 15, 2016 by Pds314

[Gman_builder]

I see. 

I was testing an engine last night and I realized that max performance was 43.8 rad/s at 157 m/s.

The prop was huge

I planning on adding another couple rows of Junos, as it couldn't reach disintegration speed(or DS)

Should I go with adding Juno's, or making a better prop in order to increase RPM and speed?

[Pds314]

5 minutes ago, Gman_builder said:

I see. 

I was testing an engine last night and I realized that max performance was 43.8 rad/s at 157 m/s.

The prop was huge

I planning on adding another couple rows of Junos, as it couldn't reach disintegration speed(or DS)

Should I go with adding Juno's, or making a better prop in order to increase RPM and speed?

You could probably honestly just make pitch adjustments to the current prop to reach disintegration speed. 157 m/s is very impressive in any case.

Edited July 15, 2016 by Pds314

[Gman_builder]

Just now, Pds314 said:

You could probably honestly just make pitch adjustments to the current prop to reach disintegration speed. 157 m/s is very impressive in any case.

I had minimum pitch In order to maintain the speed I was at.

The only reason this engine would disintegrate is the forward pull of the shaft overcoming the thrust bearing.

I implemented a double thrust bearing and I havn't gotten it to fail to date in flight. So I am not sure what the max RPM is but I am confident it is above 50 rad/s.

However, if what you are saying about prop expansion is true, I should put a better prop on the shaft. But I don't really know how to go about making a expansion-less prop. On the other hand I could go the easy way and add more blowers at the cost of a performance hit in order to try and increase my RPM to DS.

[Pds314]

1 minute ago, Gman_builder said:

I had minimum pitch In order to maintain the speed I was at.

The only reason this engine would disintegrate is the forward pull of the shaft overcoming the thrust bearing.

I implemented a double thrust bearing and I havn't gotten it to fail to date in flight. So I am not sure what the max RPM is but I am confident it is above 50 rad/s.

However, if what you are saying about prop expansion is true, I should put a better prop on the shaft. But I don't really know how to go about making a expansion-less prop. On the other hand I could go the easy way and add more blowers at the cost of a performance hit in order to try and increase my RPM to DS.

Well, it's not just props. I'm fairly sure anything to which physics applies that isn't being contained by a physicsless cage will break down above 51 rad/s. Like look at Azimech's spinning shaft in the GIF he posted?

Edited July 15, 2016 by Pds314

[The Optimist]

On 7/13/2016 at 10:00 PM, Pds314 said:

You're making something bigger than the SPH?

I need to offset wheels and engines in order to reduce part count.

[Pds314]

5 minutes ago, The Optimist said:

I need to offset wheels and engines in order to reduce part count.

Oh. I see. Yeah. Edit the line in the file. I should do that too, come to think of it.

Wow. Realizing just what "physicsless part" actually means.

You can literally make a beam out of octo struts, put half a dozen engines of any sort on the end, and it will not flex no matter what you do.

Make a shaft of struts and it will not break or bend, no matter what.

Edited July 16, 2016 by Pds314