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

[Jakalth]

Yeah, I haven't said much lately... Mostly been frustrated with trying to get a working contra prop bearing working. Up to 15 different designs tried, all fail in some way... I even tried making one based on your working Counter rotating rotor heli. Can get over half of them to work as electric, with very limited lift capabilities, but none work using jet engines.

I've even been trying to get a propeller driven aircraft working. Limited success there as well. Only have this one that works: A simple but big bi plane.

Flies ok. Takes off at a little over 20 m/s. Top speed? pushing 60 m/s, in a hard dive... Flies about 33 m/s in level flight. That's about it. Not a lot of fuel either. The props look a bit odd, but that was the only way I could get enough thrust out of that small of a prop.

Other then that, other then making some bearings, I've had little more then failure after failure as of late..

[Redshift OTF]

Good to see the evolution of the engine continues! Everyone likes new stuff as well as innovation which would explain the popularity.

[Azimech]

I'm frustrated with my current inability to make a 90 degrees gearbox like shown in this picture:

These are two turboshafts (pretty strong ones too) set up to drive a vertical shaft a la this one:

Problem is: either the colliders aren't being respected (parts fly through) or the slip is near zero (teeth bite, stalling or jamming rotation).

And actually the problem is not my building skills, it's finding a trick in Unity 4.5 to make something that's virtually impossible, possible with stock parts.

Most of all: we need Unity 5!

[Redshift OTF]

Maybe use the I-Beams instead of the 1x1 panels? It worked on the cogs I made earlier. Or maybe the cylindrical fuselage isn't strong enough, wobbles and cause collision errors.

[Azimech]

I might try that. :-) until now I've tried landing gear with panels. They work nicely in a parallel configuration, very low drag.

But that changes at 90 degrees: you need some sideslip and those wheels are unsuitable as everyone experienced when building a rover with them.

With panels and beams it's even worse.

I'd like a frictionless drive! Wow! I've got an idea!!

[Lothsahn]

Funny thing is ... people don't respond to the new ones. Can imagine, not .... or exiting at all. But they're being downloaded like crazy!

Was busy trying to build a p38...

Only problem is it doesn't fly. Too heavy for the wings, and the props just don't make enough thrust--even stacking them I don't think I can make a correct looking stock version that'll be light enough to fly. I think the mk2 parts are just too heavy.

The Juno engines are running constantly at 40 rad/s, and still only get about 13 m/s.

Only 285 parts, with 2 engines though!

[Azimech]

I've learned a lot about props lately. I try to build props that let the engine run at about 22 rad/s at full load at sea level on the test stand - due to my computing power my turbines have a problem with high speeds. I used to think 29 rad/s was the limit before RUD but now I have one capable of 32.

Your prop, how many segments per blade? How many blades? How many blades stacked? Blade angle?

I could upload my current prop as a sub. It's a quad blade, four times stacked, 4 segments per blade. Blade angles: two at 45, two at 55. With this single prop on my newest 12 blower, I can reach 95m/s at 6 kilometers. If you don't have Part Angle Display, I suggest you get it.

A P38 would be a nice experiment ... would you mind if I build one? Same as always - large part count because I build a fuselage from wing segments.

Edited March 7, 2015 by Azimech

[Redshift OTF]

Was busy trying to build a p38...

http://lothsahn.com:3172/kerbal/screenshot53.png

Only problem is it doesn't fly. Too heavy for the wings, and the props just don't make enough thrust--even stacking them I don't think I can make a correct looking stock version that'll be light enough to fly. I think the mk2 parts are just too heavy.

The Juno engines are running constantly at 40 rad/s, and still only get about 13 m/s.

Only 285 parts, with 2 engines though!

You got a download for that? Looks nice!

[Jakalth]

I've found running simpler props like that at an extreme angle, nearly pointing strait forward, gives more thrust. But I can't seem to match Azimech's prop efficiency/thrust that way.

As for high speed turbines, the way I've been setting up my turbine blades lately, they don't seem to expand, at all, even at the high rotational speeds. I've been setting them so 2/3 of the blade is on one side of the turbine shaft, while the other 1/3 of the blade sticks through, and out from, the other side of the shaft. Only hickup I sometimes get is an "over excited" turbine that twitches violently after being exposed to extreme RPM's. Doesn't cause anything to explode, but does cause the prop to start spinning erratically, even with the engines turned off.

I suppose, if I could reliably recreate this turbine twitching, I could possibly use it as a form of glitch drive.

Edited March 7, 2015 by Jakalth

[Azimech]

Yep :-)

Javascript is disabled. View full album

You can choose:

The plane: http://kerbalx.com/crafts/1300

The prop: http://kerbalx.com/crafts/1299

[Jakalth]

so, a 90 deg gear box you say... you could try this test rig.

the gears seem to work. at low speeds at least. not sure how they handle high speeds. the test rig is not setup for that. modified the gears off the synchropter I made earlier. Not sure how this compares to what you may have already tried.

Download: 90 deg test rig.

Edited March 7, 2015 by Jakalth
derp... forgot the link...

[Azimech]

Interesting, Jakalth! The problem with rotors is not the speed (they turn quite slow compared with props anyway) but the force. I'll test it, it's always useful for something (driving a camshaft for example).

[Lothsahn]

I've learned a lot about props lately. I try to build props that let the engine run at about 22 rad/s at full load at sea level on the test stand - due to my computing power my turbines have a problem with high speeds. I used to think 29 rad/s was the limit before RUD but now I have one capable of 32.

Your prop, how many segments per blade? How many blades? How many blades stacked? Blade angle?

I could upload my current prop as a sub. It's a quad blade, four times stacked, 4 segments per blade. Blade angles: two at 45, two at 55. With this single prop on my newest 12 blower, I can reach 95m/s at 6 kilometers. If you don't have Part Angle Display, I suggest you get it.

A P38 would be a nice experiment ... would you mind if I build one? Same as always - large part count because I build a fuselage from wing segments.

I would LOVE it if you built a P38. I found two things:

1) It virtually eliminates the torque issues with single-engined planes

2) Any difference in thrust between the left and right engines causes huge problems

My prop on the p38 is 1 segment per blade, 1 blade stacked, roughly 45 degrees (but I can't tell specific blade angles--not sure how you do--possibly Part Angle Display?)

Even with 4 blades stacked, 8 blades per shaft, it wouldn't take off. I kept adding wings, and finally got it to take off, but realistically there's no way for that plane to fly--even with jets, the weight to wing ratio is way too high. It did get going at a reasonable speed, so it wasn't purely a thrust issue... but nothing like 95 m/s.

The main problem is with the P38, it's a tricycle gear, so you can't realistically stack more than 1-2 segments per blade. If I could put 4 segments on a blade, it would be a very different story.

- - - Updated - - -

You got a download for that? Looks nice!

Sure. I didn't provide one because I figured nobody'd want a plane that doesn't fly.

Two download links:

P38 Lightning

World Traveler

The World Traveler is a flyable version that's ugly and laggy. The props shouldn't ever jam on you--It'll only fly up to about 6-10k, and even when I hacked gravity, climbed to 14k, unhacked gravity and went into a 200 m/s dive, the engines kept running like a charm.

It flies like a dog--way too little thrust for the weight, and it turns incredibly slowly. But I just wanted to see how many wings would be needed to make the p38 fly. Part of the main problem with the P38 is the COM--it needs to be way further back than it is for a good plane.

If you fill up all the fuel tanks on the World Traveler, it still CAN take off. I doubt it can actually circle the globe, but those engines will run for a LONG time.

The P38 engines are capable of up to 40 rad/s with a .04 physics delta.

Edited March 7, 2015 by Lothsahn

[Lothsahn]

I wonder if someone can break the 100 m/s in level flight barrier, before I do :-)

Challenge ACCEPTED.

8 blowers, 4 per shaft, counter-rotating. That said, it has less power than yours. I was only able to achieve 85-95 m/s at 6k. Max altitude unknown--going to refine the design and add drop tanks.

Note: For this screenshot, I did enable infinite fuel, but I expect to do it with no cheats once I trim the craft and add drop tanks. I'll add a download once the craft is trimmed out. There are no landing gears on the craft as they are jettisoned after launch. Don't remember the exact partcount, but it's not very high...

Azimech, could you make a reversed version of your prop (for pushers) so I can look at putting it on this thing?

Edited March 8, 2015 by Lothsahn

[Jakalth]

Ok... and the best I've done is a slow bi-plane and a big(ish) delta winged aircraft that can do 56 m/s @1800 Km using two puller props. The delta winged aircraft can hit just over 103m/s. But only in a nearly vertical dive... My guess is my props are still not good enough. The engines are not having any issues spinning the props I'm using at very high rad/s(don't know how high, don't have the mods installed... yet). And yes, these engines, without a load, can easily summon the essence of the Kraken as they go completely mental... moments before detonating...

But... I think my nephew is right. This game needs more rocket propelled feet.

[Lothsahn]

Ok... and the best I've done is a slow bi-plane and a big(ish) delta winged aircraft that can do 56 m/s @1800 Km using two puller props. The delta winged aircraft can hit just over 103m/s. But only in a nearly vertical dive... My guess is my props are still not good enough. The engines are not having any issues spinning the props I'm using at very high rad/s(don't know how high, don't have the mods installed... yet). And yes, these engines, without a load, can easily summon the essence of the Kraken as they go completely mental... moments before detonating... :huh

If you can do 56 m/s at 1800 Km, you'll go quite a bit faster higher up. I don't remember the speed of this craft at sea level, but it's probably not THAT far off from what you're getting. However, the bigger the craft, the more the drag, so the slower it will go. That's why I tried to keep this one as small as possible for max speed. If you could get your craft up to 12km, you might hit 100 m/s.

That said, you really should install VOID. Being able to tell the rad/s of rotation is very helpful. I used to make a rig which had two engines pulling on each other, but the ksp runway isn't perfectly level. I tried to count RPM's manually at low power settings, but that was inaccurate too. VOID makes it so much easier.

When designing, keep these properties in mind:

1) Engine Efficiency - Easily measured by how many rad/s you can get at a very low power setting (like 5-10%) with an empty shaft. By making small changes to the engine at such a low power setting, with VOID, you can see how they help or hurt the efficiency. I generally shoot for a power setting that gives 20 rad/s or so and make changes from there.

2) Prop Efficiency - Larger props usually have better efficiencies than small props, so consider adding blades. Someone also mentioned that changing the angle of the blades may help a lot--especially at high angles.

3) Engine Max RPM - This is a key characteristic of the engine, and in conjunction with the prop size, determines the maximum altitude the craft can operate at. Higher altitudes have less wind resistance, allowing the prop to spin faster. This is generally limited by the expansion of the turbine blades as the shaft spins faster and faster. Eventually, they'll collide into something, creating "FUN".

4) Max RPM failure behavior - Some engines explode catastrophically, others just jam.

5) Engine Power - A combination of the # of jets and the engine efficiency.

6) Engine Weight - In general you want to minimize especially the weight of the spinning shaft. A heavier shaft + propeller will reduce efficiency.

7) Engine Size - Bigger engines typically can have a higher max RPM and weigh more.

8) Pusher/Puller - Some engines may work fine as a pusher, but a puller will rip the prop right out of the engine, or vice versa. Positioning of wheels affect this.

9) Max Propeller weight/power - Heavier props may fall out of an engine, especially when mounted horizontally. Also, props with a lot of blades can pull harder on the engine, ripping the shaft out of the engine.

For example:

My Juno D211 optimizes is a puller engine which optimizes small size and efficiency. It also simply jams (not explodes) at max RPM (if the jets are positioned properly). Max RPM can be adjusted by tilting the blades inside (as seen in the P38) at a loss of efficiency. It does NOT handle large props well, as they generally overload the bearings and cause the prop to rip out.

Avimech's engines generally have had a lower efficiency and lower max RPM than the Juno, but the bearings are much more solid, so they can handle larger and stronger props. Recent versions feature a much larger # of jets, which make them much more powerful than the D211.

Looking at the above, you might be able to get your delta wing to 100 m/s, if you can increase the max engine RPM (or increase the prop size) enough to get it up to say, 12km... Or you might just have to reduce the part counts of the plane or add blades to the props to increase efficiency. The hardest approach is probably to increase the efficiency of the engines.

Edited March 8, 2015 by Lothsahn

[Azimech]

Very good Lotsahn!

I have some things to add:

10) Blade length has been mentioned and number of blades. Number of blade segments defines blade length and the segment the furthest out produces the highest lift. It's important to note you can slide a segment down, towards the root. If you do this halfway, you won't have the irritating gap between segments at high prop speeds. In real life, it's the shape of the aerofoil that defines the lift/drag ratio of a prop. Since the shape doesn't have influence on lift, stacking multiple blades together is a fine way to increase maximum thrust. But of course mass and drag rise the same way, unlike real life. And my 4 blade 4 segmented 4 stacked prop ... has 64 wing segments for a total of 71 parts. That's not nice.

11) Blade angle is very important. Together with the other variables it defines max rpm of the engine. If have a strong feeling that the behaviour can be compared with real life. With piston engines, blade angle is set as to work like the gearbox of a car. That means: low prop pitch at low speed and low altitude. increasing throttle increases prop speed quickly, this is good for acceleration. But, at higher speeds the engines accelerate beyond their most efficient operating rpm, increasing fuel consumption, heat production and wear on the engine. If you on the other hand, set a high prop pitch at low speed, you're creating an immense amount of drag while the engine is operating below it's optimal rpm.

12) Funny thing is: turbines in KSP also have an optimum rpm range. I've discovered a very interesting behaviour which can increase max power some more.

At least I can tell you that on some turbines rpm limits are not defined by turbine blade expansion but by increasing internal drag due to it's own air resistance and especially low frequency vibrations, where an increasing amount of energy is lost in the suspension struts of the landing gears.

13) Blower angle ... took me some time to find out, this is the most important factor for a powerful engine. A difference of 1 degree can have a moderate impact, 5 degrees can make the difference between a plane that flies 30m/s at sea level or 40m/s. You need Part Angle Display for this!

14)And now the fun part! The most hated feature of the current joints system: the rubbery connections. The turbine blade expansion.

I've discovered that a blower that misses it's target slightly will create more power once the turbine blade has expanded. So I've built an engine that needed an additional starter to get the turbine up to speed but when it did, the difference was noticeable!

Edited March 8, 2015 by Azimech

[Lothsahn]

Awesome tips Azimech! I noticed the same with turbine expansion and blade length, but was not aware of the rest. I guess I do need part angle mod...

As promised, craft files attached for my speedrun (link to craft file in name).

To fly:

1) Enable SAS. Stage and go to full throttle.

2) Keep the craft going straight and pull all the way back until the craft takes off.

3) Once at 50-100m, stage again to drop the landing gear.

4) Further stages drop the drop tanks.

SpeedRunner:

Time to climb:

<6m to 6,000m

11m to 9,000m

Top speed (level): 102 m/s at 9,235m

Maximum Speed: 170 m/s (at which point, the front engine encountered RUD, followed by a high G spin, which destroyed the right wingtip and the rear engine.)

Landing attempt was unsuccessful due to the destruction of the right wing. This problem could be corrected by changing the turbine blade angle, but it might affect efficiency.

Endurance: 20m at cruise

351 parts (plus landing gear)

And a bonus!

Speedrunner Max:

Top Speed (level): 109 m/s at 8,035m

Maximum Speed: 175 m/s (no failures)

Azimech, have you noticed that having two jets on the shaft causes the turbine blades to explode if using 4 turbine blades, but with 8, it does not? Do Jets cause actual damage to the parts? Any idea how this works? I had to reinforce the turbine blades on SpeedRunner max because throttling up to 100% would destroy the engines in short order...

Edited March 8, 2015 by Lothsahn

[astecarmyman]

When I'm flying the fw190a2 smoke (jet exhaust) comes out of the propeller shaft. Any way to fix this? (Don't want to record a smoky plane)

[_Bugs]

@Astecar

http://i.imgur.com/GbMYVjF.png

[Azimech]

When I'm flying the fw190a2 smoke (jet exhaust) comes out of the propeller shaft. Any way to fix this? (Don't want to record a smoky plane)

You want to make a video with my plane? Wow! Please post the result!

- - - Updated - - -

Great job Lotsahn! Gonna try your plane when I get home.

I've got some new technologies in my head ... gonna test them tomorrow.

Awesome tips Azimech! I noticed the same with turbine expansion and blade length, but was not aware of the rest. I guess I do need part angle mod...

As promised, craft files attached for my speedrun (link to craft file in name).

To fly:

1) Enable SAS. Stage and go to full throttle.

2) Keep the craft going straight and pull all the way back until the craft takes off.

3) Once at 50-100m, stage again to drop the landing gear.

4) Further stages drop the drop tanks.

SpeedRunner:

Time to climb:

<6m to 6,000m

11m to 9,000m

Top speed (level): 102 m/s at 9,235m

Maximum Speed: 170 m/s (at which point, the front engine encountered RUD, followed by a high G spin, which destroyed the right wingtip and the rear engine.)

Landing attempt was unsuccessful due to the destruction of the right wing. This problem could be corrected by changing the turbine blade angle, but it might affect efficiency.

Endurance: 20m at cruise

351 parts (plus landing gear)

And a bonus!

Speedrunner Max:

Top Speed (level): 109 m/s at 8,035m

Maximum Speed: 175 m/s (no failures)

Azimech, have you noticed that having two jets on the shaft causes the turbine blades to explode if using 4 turbine blades, but with 8, it does not? Do Jets cause actual damage to the parts? Any idea how this works? I had to reinforce the turbine blades on SpeedRunner max because throttling up to 100% would destroy the engines in short order...

Yes, never press F3. The list of damage updates crashes KSP. Blades go if damaged too much, central shaft parts too, that's usually the case with my 12 blower, and always the segment at the rear. I'm thinking of adapting the config file of my jet engine, I feel it's still stock KSP then.

It could be the case of the jet blast hitting and damaging the shaft instead of the blades ... the fact that 8 blades instead of 4 delays the process, supports that theory.

[Lothsahn]

It could be the case of the jet blast hitting and damaging the shaft instead of the blades ... the fact that 8 blades instead of 4 delays the process, supports that theory.

The funny thing is it's not a delay. The 4 blade engine explodes almost immediately when the jets reach some threshold of output (above 90% throttle with 8 engines), but the 8 blade engines last until at least when fuel runs out (8 minutes).

The page here says it might be part of the overheat algorithm:

http://forum.kerbalspaceprogram.com/threads/90900-Part-damage-due-to-exhaust-Important

That would make sense. That means that with 8 turbine blades, the blades have enough time to cool down (when not getting hit by one of the jets) that they don't hit the explosion overheat threshold. With only 4 blades, each blade is being exposed to jet exhaust basically constantly, getting hotter.

[Jakalth]

Finally downloaded and installed VOID and I found out something very important today. The engines on my aircraft are not very good.

The engines on the delta wing aircraft I've been testing were only oscillating between 13 and 18 rad/s at full speed on the runway, with 4 blowers and a triple stacked 4 blade prop. Not anywhere near as fast as I calculated they were. That is why I haven't been able to get reliable results... So, I built new engines. Now they are getting between 19 and 23 rad/s on the runway, with quad stacked, 4 blade props, and still only 4 blowers each. So, even stronger props then I had before. Did some testing and I was able to reach 66m/s on the runway before takeoff. Climbed up to 2000m and clocked out a top speed of 82 m/s before the right engine decided it didn't want it's turbine blades anymore and ejected them. They did not blow up, they were actually thrown out of the engine... Then the left engine decided to eject the whole turbine/prop assembly as well moments before the whole aircraft broke in two.

Yeah, I've still got some work to do here... heh

[Lothsahn]

Finally downloaded and installed VOID and I found out something very important today. The engines on my aircraft are not very good.

The engines on the delta wing aircraft I've been testing were only oscillating between 13 and 18 rad/s at full speed on the runway, with 4 blowers and a triple stacked 4 blade prop. Not anywhere near as fast as I calculated they were. That is why I haven't been able to get reliable results... So, I built new engines. Now they are getting between 19 and 23 rad/s on the runway, with quad stacked, 4 blade props, and still only 4 blowers each. So, even stronger props then I had before. Did some testing and I was able to reach 66m/s on the runway before takeoff. Climbed up to 2000m and clocked out a top speed of 82 m/s before the right engine decided it didn't want it's turbine blades anymore and ejected them. They did not blow up, they were actually thrown out of the engine... Then the left engine decided to eject the whole turbine/prop assembly as well moments before the whole aircraft broke in two.

Yeah, I've still got some work to do here... heh

That sounds like a very efficient engine, actually. I mean, except for the RUD, that's actually more powerful than the craft I posted doing 100 m/s It only does 62 m/s in level flight at sea level.

[Azimech]

This is a picture of my last attempt. I don't have data from the last dive because when I rolled it onto it's back to go vertical, the engines stalled due to air shortage, resulting in a devastating spin that tore the aircraft to pieces.

As you can see, 110 m/s at 10k. Barely.

At low altitudes it's not as quick as your planes, Jakalth and Lotsahn. It lack raw power. And it's a slow climber but it makes it up with endurance. At take-off the prop pitch does 10 rad/s, at 10k it goes 28 rad/s. Estimated flying time at full power: 51 minutes.

Also, I decided to try to see what my pc does when having all the gfx detail set to low. Much better experience. Part count: around 230. Timer stays in the green for 99% of the time.

I don't know about you guys, but my SAS fraks up big time. Can't fly with it. On the other hand, my newest flies steady with minimal trim.

When I dropped the tanks the thing started to climb with 12m/s, I was already at 9500m.

Earlier dive:

Download link: https://www.dropbox.com/s/53dq73qep1mvhik/Azimech%20PO4R%20rev_2_8.craft?dl=0

Edited March 9, 2015 by Azimech