Hue-H7 Lynx

[luizopiloto]

This one have 2 variants
Stock: https://kerbalx.com/luizopiloto/Hue-H7-Lynx
kOS: https://kerbalx.com/luizopiloto/Hue-H7K-Lynx
kOS variant uses a set of scripts to enable full cyclic controls, enabling the helicopter to be way more responsive/maneuverable.

 

[Azimech]

I like the idea!

Just did a few test flights to see what the benefits are of the flapping blade tech but at the moment it's not clear to me. I placed two FMJ's on it to see how it would hold at higher speeds but unfortunately above 55m/s the rolling force becomes too strong.

In any case, beautiful build and impressive kOS script. kOS is something I don't grok, at all.

[luizopiloto]

Flapping blades reduce the gyroscopic precession and the blade stall when moving forward. If you watch close you can see the rotor tilting to the sides to compensate those forces, and makes the craft more maneuverable because the main craft is not completely tied to the rotor.
Also, to minimize the roll when moving fast forward, try reduce the blades authority...  The forward speed will give you the extra lift you need to fly. Unfortunately, the longer blades in this design is more susceptible to this problem...

The original flapping blades design was a really good tech demo: https://www.youtube.com/watch?v=pA1e2hHXWCs
unfortunately, the original creator removed it from kerbalx...

[Azimech]

Indeed there is a large difference in control between locked and freed pivots. I tried with reduced blade angle but it doesn't really help. There could be a source of friction in your bearing, I've found such a problem a big issue in my own designs.

By the way, the inverted flight demo is cool! Any idea why it RUDded near the end?

[luizopiloto]

No, RUDs are totally random... can probably be caused by a bug, because sometimes the blades hit the cargo ramp w/o visually getting close to it... Yarg had this problem with one of his designs and almost freaked out...
It's not called Krakentech for any reason...

[Azimech]

True, I've had my fair share the last 4.5 years.

[EpicSpaceTroll139]

Nice work! I've tried working on a cyclic script every now and then, but I never really dedicated enough time to actually make it work. Glad someone did.

I too have been having problems with blades hitting parts that aren't visually near them. Currently having that problem with my tandem rotor heli. I fixed the bearing itself since 1.4 broke it, but the thing still blows up. The f3 menu says my rear rotor's blades are hitting the fuselage, but the fuselage is several meters below them when they spontaneously explode.  I think it means I need to completely rebuild the thing because I recall I had the problem once before when I originally built the thing and that's what fixed it. Ugh.

Edit: @luizopiloto Does the cyclic script allow the helicopter to fly without reaction wheels?

Edited May 5, 2018 by EpicSpaceTroll139

[luizopiloto]

6 hours ago, EpicSpaceTroll139 said:

...Does the cyclic script allow the helicopter to fly without reaction wheels?...

Yes... A bit slow, because the control surfaces can not move fast enough to give the force needed to maneuver  like a combat helicopter...
That's why AG3 toggles all the reaction wheels... to test if the cyclic is really doing something...

[EpicSpaceTroll139]

2 hours ago, luizopiloto said:

Yes... A bit slow, because the control surfaces can not move fast enough to give the force needed to maneuver  like a combat helicopter...
That's why AG3 toggles all the reaction wheels... to test if the cyclic is really doing something...

Might I suggest testing use of the Big-S elevons as rotor blades, or at least as control tabs on the rotor blades? They might look ugly but they respond 60% faster than the Fat-455.

[luizopiloto]

Or you can use this module manager cfg:

@PART[airlinerCtrlSrf]:FINAL
{
	@MODULE[ModuleControlSurface]
	{
		@actuatorSpeed = 250
	}
}

Now the thing moves 10x faster...

[luizopiloto]

I removed all the reactionwheels from the K variant, reinforced the rotor and added a jRCS (Juno Reaction Control System) for Yaw control... This will prove the thing can fly w/o SAS help... 

Also, I improved the script with @Aphobius help... It's way more smooth and maneuverable now if you use it in conjunction with the Module Manager config on the previous post.

[jfrouleau]

Hi, I'm the creator of the original flapping blades demo. I indeed removed this demo from KerbalX since we can now find other examples of this tech thanks to Luizopiloto. However, I did not really adopted this technique after that because of the rolling force Azimech speak of. I found it a better design to keep the fixed blades but counter the pitch force with strong elevators on the tail which are far from the CoM and thus have a good mechanical advantage like a long lever. You are right about the maneuverability allowed by the fact that the craft is not tied to the rotor which is usually large and have a good amount of kinetic energy and is difficult to change its rotation axis much like a big gyroscope. There is one thing I had in mind is to use 2 articulated rotors spinning in opposite directions to cancel the rolling force. I tried a version with contra-rotating (same shaft) but then the rotor discs tilt in opposite directions and collide with each other. So the other option is to make them on separate shaft (counter-rotating) and... this is where I left my experimentation with this. Theorically this would make a helicopter with almost no pitch or roll force caused by dissymetry of lift but it is yet to be made. Maybe my next build ? Keep the creativity going guys :-)

Oh it looks like this guy has done it ! Counter-rotating articulated rotors.

 

Edited May 11, 2018 by jfrouleau
correction

[luizopiloto]

Your flapping blades technic is the best one I know to make helicopter rotors... Specially when used in conjunction with kOS.
Even Infernal Robotics have problems to make this work right.

[jfrouleau]

@luizopiloto I'm trying to make a new rotor with flapping blades but it always wobble and I can't figure out why. Do you have any tip to help balance the rotor ? I examined your helicopter and they are very stable. I wonder what the magic trick is.

Never mind, I was stupid I just found the cause. The bearing hole was too large  

Edited May 19, 2018 by jfrouleau
Found the answer.