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

[klond]

On 5/11/2017 at 0:00 PM, klond said:

ould we use flaps or airbrakes so that the number of Junos powering the tail rotor will determine if yaw is straight, left, or right.  Anyone interested in trying this?

Feels weird quoting myself..  No takers, so here's what I came up with.

 Using @Azimech's and @jfrouleau's thrust blocker idea I have 3 Juno's here with 2 behind elevons.

 One juno blows all the time to spin the tail rotor to fight main helicopter rotor torque.  Pressing A or D adds an addition juno to the mix already spooled up to either suppliment power (rotating helicopter one way), or reduce power to neutral and let main rotor torque rotate the craft other way.

Edited May 13, 2017 by klond

[Azimech]

Yep, that's the way to do it @klond. I decided not to use it on my helicopters though, I feel the construction is too bulky and heavy while not generating the amount of thrust my big ones need.

[EpicSpaceTroll139]

On 5/13/2017 at 1:45 AM, Azimech said:

Yep, that's the way to do it @klond. I decided not to use it on my helicopters though, I feel the construction is too bulky and heavy while not generating the amount of thrust my big ones need.

After inspecting @klond's tail rotor device, I built my own larger version, and made a few changes.

While it only has one Juno blower, it produces significant thrust (I have yet to determine the exact thrust, but I'd guestimate it to be equivalent to maybe 3 Junos?).*

 Its speed and thus thrust varies with yaw control.

Yaw left: blower flap blocks Juno allowing a turbine brake flap to slow or even stop the tail rotor.

Neutral: blower flap is open, but turbine brake flap is still engaged, restricting the rotor rpm so it produces moderate thrust.

Yaw right: blower flap is open and turbine brake is disengaged, allowing the tail rotor to spin up and produce maximum thrust.

Here's a demo viewing from the front:

In the morning I might work on decreasing spool and braking time.

Would you want to test this on one of your Asura or Titan line Helis? I designed it such that it should be compatible, and would appreciate feedback. (Left side tractor, good with clockwise rotors like yours and mine). Actually, if anyone wants to test it on their stuff please let me know! 

You wouldn't want to put this on a production heli though, it currently has a problem that it breaks after timewarp, something I've discovered a couple of my Helis have too. Going to work on a fix for that.

*Ok I just realized that I severely overestimated the thrust of the tail rotor. It was not producing multi-Juno thrust. I'm going to do some more modifications before releasing it

Edited May 15, 2017 by EpicSpaceTroll139

[Azimech]

Amazing stuff, EST!  Yes I'll test your tail rotor.

[Rath]

I wonder if it could be possible to make a system for very, very large helicopters with a single rotor to have their left and right rotation be controlled by braking on the main engine shaft to transfer rotation to the airframe?  It probably won't compete but it would be a very interesting method of turning in the direction your rotor is turning.

[selfish_meme]

2 hours ago, Rath said:

I wonder if it could be possible to make a system for very, very large helicopters with a single rotor to have their left and right rotation be controlled by braking on the main engine shaft to transfer rotation to the airframe?  It probably won't compete but it would be a very interesting method of turning in the direction your rotor is turning.

 

 

I made a brake this way once before, I used it for turrets, I guess using something similar to the method above on the main rotor would work too, could make for a very manoeuvrable heli

Edited May 15, 2017 by selfish_meme

[Rath]

2 hours ago, selfish_meme said:

I made a brake this way once before, I used it for turrets, I guess using something similar to the method above on the main rotor would work too, could make for a very manoeuvrable heli

If it was contra-rotating it could turn in both directions very quickly I guess.  A very large heli that turns very fast?  yes please.  If we could find a way to attach it to a and d keys that would be great.

[EpicSpaceTroll139]

Turns out the thing produces less thrust than I thought, but I have some ideas for how to improve it. Still might be fun to test out. 

https://kerbalx.com/EpicSpaceTroll139/Large-Tail-Rotor-Prototype

[Azimech]

7 hours ago, Rath said:

I wonder if it could be possible to make a system for very, very large helicopters with a single rotor to have their left and right rotation be controlled by braking on the main engine shaft to transfer rotation to the airframe?  It probably won't compete but it would be a very interesting method of turning in the direction your rotor is turning.

I use some braking on single main shaft when going to hover, the resulting loss in lift is greater than the amount of rotational force you get from it.

My main method: use three jets on the tail, the first always running, the other two depending on main engine power setting, forward speed (cancels out most of the yawing effect) and the third for fast yawing. But, shutting off the first has a tremendous yawing effect and is great fun to use. Can be augmented with a Boost Flap for even faster control.

[Azimech]

This is very interesting, a new feature (I hope) in 1.2.9:

 

[Rath]

I wonder if by using the same concept as braking the shaft, you could make stock realistic reaction wheels?  Spin them up using rover wheels or something, that still works, right?

Edited May 15, 2017 by Rath

[Azimech]

2 hours ago, Rath said:

I wonder if by using the same concept as braking the shaft, you could make stock realistic reaction wheels?  Spin them up using rover wheels or something, that still works, right?

Yes, that works :-)

[klond]

 Gotta keep this thread alive.

 One Juno Turboprop has been updated.

KerbalX

[qzgy]

Hmm.... Need help with this.

So I have a helicopter that I have somewhat flying. It goes in the air. Problem Is, I can't control it. Also, it is horribly optimized.

Can anyone help/ give tips?

Craft on KerbalX. https://kerbalx.com/qzgy/Mil-Mi24

[EpicSpaceTroll139]

6 hours ago, qzgy said:

Hmm.... Need help with this.

So I have a helicopter that I have somewhat flying. It goes in the air. Problem Is, I can't control it. Also, it is horribly optimized.

Can anyone help/ give tips?

Craft on KerbalX. https://kerbalx.com/qzgy/Mil-Mi24

Pictures might help to get a diagnosis faster around here, but I'll check out the craft in a few mins.

How much reaction wheel torque do you have? I usually have something on the order of 4 large reaction wheels or more for even my E-18 medium single rotor line.

[Azimech]

10 hours ago, qzgy said:

Hmm.... Need help with this.

So I have a helicopter that I have somewhat flying. It goes in the air. Problem Is, I can't control it. Also, it is horribly optimized.

Can anyone help/ give tips?

Craft on KerbalX. https://kerbalx.com/qzgy/Mil-Mi24

First thing I notice: for someone just starting to be a turbohead, this is a remarkable design. You're a good student!

Analysis:

After starting the engine the first thing I got was a massive RUD in the rotor assembly. Then I saw something interesting: floating rotor blades bent from there normal angle and a large amount of blades on the ground. I also saw a bearings made of solar panels and antennae.

Suggestions so far:

• Interesting fact: more rotor blades than three doesn't necessarily improve things in stock aero. Often the opposite is true. You've got 170kg per blade segment providing lift & drag but also gyroscopic precession. 
• Stacking blade segments is doing the same as having more rotor blades. To give you a figure, I use a three blade rotor with two blade segments for a 10 blower engine and a 2.5m. turbine wheel. I use a three blade rotor with four blade segments for a 50 blower engine with 8 short I-beams for the turbine.
• When attaching blade segments, attach them to their direct parent. Don't attach all of them to a central point. You'll increase the risk of a kraken attack.
• Rotors only become efficient above a certain RPM or as we use in KSP: angular velocity in rad/s. Rotors are efficient above ~ 24 rad/s. Adjust the amount of blade segments and/or blade angle to match this.
• When flying forward, the more blade angle you have, the more you'll experience "retreating blade stall". There are multiple ways to cope with this but this is a topic for later (it would take up a quarter of a page).
• Helicopters benefit greatly from having the CoM in front of the turbine shaft.
• Suggested mods: V.O.I.D. for reading engine/rotor speed (switch focus to the shaft), Part Angle Display for finetuning rotor blade angle, Editor Extensions for various building reasons and Collide -o- Scope for building bearings, especially bearings based on landing gear for the turbine shaft.
• A bearing should be able to cope with the forces it has to endure. Collider integrity seems to depend partly on part mass. You've used a very light bearing with a very heavy rotor. Download the Azi27 and Azi30 from KerbalX to compare.
• A larger radius for the turbine wheel increases efficiency. In case the turbine wheel is segmented, those segments tend to expand from the shaft at higher engine speeds (typically above 25 rad/s). The more distance from the center of the shaft, the more effect. Maybe a better choice than vernors can be found.
• Every J-20 has its own air intake. Maybe it's an idea to reduce the amount and have them all facing forward to reduce drag during forward flight.

 

This is what happens in KSP 1.3. Pictures 2-4 are with "unbreakable joints" and "no crash damage" enabled. I'll load it up in 1.2.2 and see what happens.

It works allright in 1.2.2. Something else I noticed but best shown with a picture:

 

• Here you see the exhaust thrust vector hitting the vernor nearly center. Engine efficiency improves dramatically when you make sure it hits the outer edge of the turbine element(s).
• You can hit "t" to enable surface attach when using EEX, then you can attach blowers directly to the parent part. In your case with 60 blowers, it means 60 parts less.
• It improves even more when you replace all those air intakes with a few 1.25m engine nacelles or engine pre-coolers.

Edited June 12, 2017 by Azimech

[EpicSpaceTroll139]

10 hours ago, qzgy said:

Hmm.... Need help with this.

So I have a helicopter that I have somewhat flying. It goes in the air. Problem Is, I can't control it. Also, it is horribly optimized.

Can anyone help/ give tips?

Craft on KerbalX. https://kerbalx.com/qzgy/Mil-Mi24

Ok I checked it out and I would suggest putting a couple Junos on the tail thrusting towards the right. 

While that vernor system can kind of deal with the torque from the main rotor, it isn't going to last too long given the their ISP, and leave it much easier to turn one way than the other.

While I think having more than 3 rotor blades is perfectly reasonable, I would definitely not suggest having two rotors clipped inside eachother with each blade individually attached to the hub. That's a recipe for:

I'll do some testing, but I think you can ditch one of the clipped rotors and let the rotor spin at much higher rpm. As Azimech said, rotors tend to be more efficient at high spin rates.

Oh, and I'd also suggest resetting the cockpit as the root, otherwise you get an odd control point.

Nice work though!

Edit: @qzgy I would suggest changing your bearing a bit. The solar panel bearings tend to work best when one bearing is at or below the plane of the turbine (you're good for this one), and the other is at or above the plane of the rotor (this one I highly recommend changing).The bearings also probably work better if the solar panel disks are situated around the middle of the spindly bit of the antennas, instead of around the bulb, but more importantly, they should not rub against the turbine wheel, as that will cause friction losses, and possibly make it more likely to break.

I'll get some pictures. I modified the rotor system by removing the extra clipped rotor, re-positioned the bearings (well actually just the top one, I only moved the solar panels a little on the lower one), and added an antenna as a low-friction rotor retention system. It works much more reliably and is easier to control. Not easy to control mind you, but easier.

Edited June 12, 2017 by EpicSpaceTroll139

[Azimech]

I have to be honest, I always have problems with the antennae-solar panel bearings. Without changing anything to the bearing, I now have this problem every time as shown in this two-pic album
I've changed the blower assembly to a quick & dirty 40 using a narrow setup, 10 blowers per cubic strut. While I was the first to choose for a radial setup using 20 blowers, I feel the construction is a little bit too wide. I'll have to do more testing which setup creates more vibrations, I always had the idea a radial setup provides a more smooth torque delivery.

Next thing I'm going to try is to replace the original bearing with my newest.

 

 

[EpicSpaceTroll139]

@Azimech I also had problems with the bearing right out of the box. I did some adjustments of the bearing system, and it became much more reliable.I'll post a picture of the modifications I made to it when I get back from class.

Your bearings probably are stronger, but the Mil out of the box does not currently represent what solar panel bearings can do.

I was just thinking that I've been meaning to do scientific comparison between one of your engines and one of mine. Would be interesting to see what things each can do better than the other.

Might be hard to find a frame equally compatible with both systems. Or it might not, who knows .

 

Edited June 12, 2017 by EpicSpaceTroll139

[Azimech]

@qzgy I'm going to continue on my own designs now and leave this one as it is. Your Hind is a lot more controllable now. There's a lot that can be improved from here and this was done quick & dirty. Anyway, hope you like it :-)

List of modifications:

• removed the reaction wheels in the rear and placed larger ones in front,
• replaced the engine with one of my own,
• reduced amount of blowers from 60 to 40,
• engine speed increased from 10 rad/s to 27 rad/s,
• placed three Juno's on the tail to replace the vernors,
• replaced the structural fuselages with fuel tanks,
• replaced the parachutes with probe cores (personal preference ;-)),
• rerouted fuel lines,
• reduced the amount of rotor segments from 50 to 15,
• Increased the amount of air intakes,
• reduced part count from 448 to 206,
• reduced the mass from 63.7t to 61.3t while increasing fuel amount with 2400 units.

By the way ... I really like the fact you chose a Hind as your first helo. It's my favourite!

Download link.

[EpicSpaceTroll139]

@Azimech @qzgy

Ok, so here's a couple pictures of what I've done with it.

I made the changes I mentioned earlier, moving the top bearing so it is just above the plane of the rotor, and re-positioning the solar panels to hug the spindle of the antennas instead of the bulbs. The antenna you see just above the turbine is attached to one of those mk0 tanks, and acts as a low friction retention pin for the rotor. Like Azimech, I adjusted the blowers to blow near the outer edges of the turbine blades. Didn't do a perfect job, but that can be fixed later.

After those adjustments it seemed to be flying ok, but the rotor seemed to have some kind of strange resonance mode where it the blades would flex onto a different plane, wobbling around like a top with the degree of the tilt increasing slowly until it hit the tailboom and then, well, you can imagine what happened then. 

I bent the blade tips down to try to help deal with another problem, that of dealing with asymmetric lift at speed, and that apparently had a side effect of dampening out that resonance mode. I still wasn't able to fix the control problems at speed though. At speeds above 25-30m/s, the asymmetric lift causes the thing to roll to the right and go into a downward spiral, and it is nearly impossible to get out of it.

I'll have to check out Azimech's version.

[Azimech]

So ... did some testing. I don't like fully electric helicopters but the use of just two reaction wheels, a probe core and RTG does reduce fuel consumption so ... think I'll upgrade all of them with this.

[Azimech]

While almost all of my designs were having 8 short I-beams as turbine blades, I recently started to look at alternatives. I think I've found a decent one:

The MK2 drone cores have a reasonable impact rating of 20 m/s. While it is true the I-beams have a rating of 80, the fact they expand from the shaft at high speeds is the most common source for engine damage in my designs. And they snap off easily when they hit something. The MK2 cores can't expand because their CoM is in line with the rest of the shaft.

Not only that, they can withstand a higher temperature and have more heat capacity. Plus they provide a tiny amount or roll torque, just enough to validate the fact the construction is 220kg heavier (1 RTG is needed). Another bonus is the control I'll have over the rotor blade pitch.

I might starting to use a few Panthers as well, with the MK2 cores it's easier to use the afterburner without overheating the engine.

 

[EpicSpaceTroll139]

3 hours ago, Azimech said:

While almost all of my designs were having 8 short I-beams as turbine blades, I recently started to look at alternatives. I think I've found a decent one:

<snip>

And they snap off easily when they hit something. The MK2 cores can't expand because their CoM is in line with the rest of the shaft.

Not only that, they can withstand a higher temperature and have more heat capacity. Plus they provide a tiny amount or roll torque, just enough to validate the fact the construction is 220kg heavier (1 RTG is needed). Another bonus is the control I'll have over the rotor blade pitch.

I might starting to use a few Panthers as well, with the MK2 cores it's easier to use the afterburner without overheating the engine.

Out of curiosity, have you tried one-piece turbines* using parts such as fairing bases? Like the Mk2 cores, they don't expand as their COM is in line with the shaft. Is the reason for the multiple turbine elements because they withstand heat better? I imagine heat tolerance might be a bigger issue for your helis as their lower turbine radius (1.25meterish) requires more thrust impinging on the turbine than my over-sized (1.88meterish) turbines for the same torque... I think... Correct me if I'm wrong.

*I've actually tried multi-part turbines, though the reason I've used them was for space saving reasons. For example on coaxial designs I can have a bearing for one rotor inside the turbine for the other

Edited June 20, 2017 by EpicSpaceTroll139

[qzgy]

5 minutes ago, EpicSpaceTroll139 said:

Out of curiosity, have you tried one-piece turbines* using parts such as fairing bases? Like the Mk2 cores, they don't expand as their COM is in line with the shaft. Is the reason for the multiple turbine elements because they withstand heat better? I imagine heat tolerance might be a bigger issue for your helis as their lower turbine radius (1.25meterish) requires more thrust impinging on the turbine than my over-sized (1.88meterish) turbines for the same torque... I think... Correct me if I'm wrong.

*I've actually tried multi-part turbines, though the reason I've used them was for space saving reasons. For example on coaxial designs I can have a bearing for one rotor inside the turbine for the other

I believe he has, using a heat shield for his new smaller turbine design.

@Azimech, correct me if I'm wrong\

 

Also, mind showing a picture of your coaxial design to me? I've been trying to make a coaxial thing for a while, haven't been able to get something small enough that's powerful enough...

Edited June 20, 2017 by qzgy