St4rdust

KSP Loading... Preview: Breaking Ground - Propeller and Helicopter Blades

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The helicopter blades look like your modeller used a toy quadcopter or wind turbine as his reference. These rotors don't look like any blades I've ever seen on a real helicopter. Helicopter rotors usually a constant chord and if there is taper it's only near the tips. The also have twist, but it isn't as obvious as on a propeller. You could differentiate the blades with different tip shapes instead of the odd color splotch. A root cutout and adding a trim tab could be used to add visual interest instead of a weird planform.

 

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Nice, especially the props - small-diameter propellers will make all kinds of designs feasible that previously weren’t.

I would pick a nit about the helicopter rotor blades though: RL helo blades don’t usually have that leaf shape, they’re generally just elongated rectangles more or less. 

Do the helicopter blades also implement cyclic that works with SAS and pitch/roll? It would be cool to be able to make a chopper that’s easy to fly without reaction wheels to paper over the cracks.

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4 hours ago, RocketSimplicity said:

How will these propellers differ from using elevons? Of course, I know they can pitch, but how will they be more effective than elevons in terms of producing thrust? I think they might have greater lift area. Could a dev confirm this?

At least they'll be solid parts that won't get funky with game physics, that's already something.

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Posted (edited)
10 hours ago, nestor said:

LF engines and propellers are Breaking Ground content.

Welp

(guess im buying the dlc)

Edited by KerbolExplorer

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Guess I'll really only focus on piston engines, gearboxes and suspensions from now on <_<

2 hours ago, Quoniam Kerman said:

At least they'll be solid parts that won't get funky with game physics, that's already something.

We don't know that, yet.

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Posted (edited)

I wonder what kind of ksp aerodynamic characteristics those blades will have - how long until someone try to make a plane using only those as wings ? ;)

Edited by sgt_flyer
Order

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25 minutes ago, sgt_flyer said:

I wonder what kind of ksp aerodynamic characteristics those blades will have - how long until someone try to make a plane using only those as wings ? ;)

I give it about five minutes tops.:)

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1 minute ago, Chryssalid 8492 said:

I give it about five minutes tops.:)

You read my mind.

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Oh oh oh made my day...again :D .Thank you!!Looks solid!

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Besides the helicopter blades generally being bigger (and aesthetics), I wonder what the functional differences will be between the two classes.  I would think the propeller blades would be intended to spin faster, but not sure how this would be reflected though in-game properties.  Perhaps helicopter blades have more bite (more air resistance but more thrust) to reflect higher pitch?

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24 minutes ago, Aegolius13 said:

Besides the helicopter blades generally being bigger (and aesthetics), I wonder what the functional differences will be between the two classes.  I would think the propeller blades would be intended to spin faster, but not sure how this would be reflected though in-game properties.  Perhaps helicopter blades have more bite (more air resistance but more thrust) to reflect higher pitch?

Looking at this image:

D-p51xJW4AEC8qR.jpg

We have a 2.0 meter prop blade, and a 2.0 meter helo blade. The Helo blade has a flat profile, the prop blade has a twisted profile. I guess the twist IRL would be more useful when forward velocity is significant compared to the blade velocity. How will this factor in to KSP when its a single part that presumably has 1 lift vector.

I wonder if its going to be a bit funky, and not like a normal aerodynamic part. A problem with current props, that won't be solved by this part if it just is variable pitch (but it would help part count), is that (due to the low rotational rate) to go fast, you need very high blade pitch. High blade pitch means massive cosine losses, as most of the lift is pointed away from the direction of flight.

I wonder if this part is being cheeky, or if that is literally what it does:

21 hours ago, St4rdust said:

This blade part can be used to convert lift into thrust

If it basically cancels out the lift, and instead applies a thrust, then those massive cosine losses disappear, and props can function much better even with a low RPM limit.

It would also be cool if the helo blades somehow gave the option for cyclic control (and if they generate "KSP thrust" maybe their thrust curve has a much lower max velocity?)... otherwise, what's the point of a 2m prop blade and a 2m helo blade?

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Posted (edited)
7 minutes ago, KerikBalm said:

I wonder if its going to be a bit funky, and not like a normal aerodynamic part. A problem with current props, that won't be solved by this part if it just is variable pitch (but it would help part count), is that (due to the low rotational rate) to go fast, you need very high blade pitch. High blade pitch means massive cosine losses, as most of the lift is pointed away from the direction of flight.

I wonder if this part is being cheeky, or if that is literally what it does:

Yeah, I was thinking the same.  Given the significant difficulties making props/rotors work with normal aerodynamic parts, I'd be fine with a "magic" part that eats fuel [edit: eats torque / rotation / angular momentum / whatever] and puts out thrust according to some simplified model.  That's kinda like what the jet engines and intakes do - they're certainly not modelling the little bits of air going through the intakes and turbomachinery, but they work fine from a gameplay perspective.

Edited by Aegolius13

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So, um... the way I have been making helicopters is using Brikoleur's guide, in which you control vertical speed by pitch of the rotor. So: does this produce lift in the normal position? Or do you have to turn it slightly?

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7 hours ago, KerikBalm said:

Looking at this image:

D-p51xJW4AEC8qR.jpg

We have a 2.0 meter prop blade, and a 2.0 meter helo blade. The Helo blade has a flat profile, the prop blade has a twisted profile. I guess the twist IRL would be more useful when forward velocity is significant compared to the blade velocity. How will this factor in to KSP when its a single part that presumably has 1 lift vector.

I wonder if its going to be a bit funky, and not like a normal aerodynamic part. A problem with current props, that won't be solved by this part if it just is variable pitch (but it would help part count), is that (due to the low rotational rate) to go fast, you need very high blade pitch. High blade pitch means massive cosine losses, as most of the lift is pointed away from the direction of flight.

I wonder if this part is being cheeky, or if that is literally what it does:

If it basically cancels out the lift, and instead applies a thrust, then those massive cosine losses disappear, and props can function much better even with a low RPM limit.

It would also be cool if the helo blades somehow gave the option for cyclic control (and if they generate "KSP thrust" maybe their thrust curve has a much lower max velocity?)... otherwise, what's the point of a 2m prop blade and a 2m helo blade?

Now those are valid questions which really deserve an answer.

By the way, I don't mind the stock behaviour because all my stock turboprops and helicopters are fine they way they are.

@RoverDude is there a new module/library for these parts or does it just use Errordynamics as usual?
 

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They are not normal lifting or control surfaces.

they are in aerodynamics part group.

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2 minutes ago, JPLRepo said:

They are not normal lifting or control surfaces.

Cool, thanks for the clarification...

I guess this means that we might not be able to use them as wings

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2 minutes ago, JPLRepo said:

They are not normal lifting or control surfaces.

they are in aerodynamics part group.

It's not clear to me what you mean by that because I had the impression all lifting & control surfaces are part of the aerodynamics group.

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42 minutes ago, Azimech said:

It's not clear to me what you mean by that because I had the impression all lifting & control surfaces are part of the aerodynamics group.

ok so the first sentence was in response to this:

Quote

I wonder if its going to be a bit funky, and not like a normal aerodynamic part. A problem with current props, that won't be solved by this part if it just is variable pitch (but it would help part count), is that (due to the low rotational rate) to go fast, you need very high blade pitch. High blade pitch means massive cosine losses, as most of the lift is pointed away from the direction of flight.

They are not normal lifting or control surfaces.

The second sentence was someone asked what part category they were going to be in, to which the answer is:

they are in aerodynamics part group.

 

To clarify a bit further, these are blades. Not motors. so they don't have thrust curves. They produce lift - equating to thrust.
You have to spin them using an EC rotor or the new upcoming LF/Air rotors that were mentioned in another announcement thread.

They do not suffer the same issues as the existing lifting and control surfaces when you try to use the existing parts as propellers.

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Posted (edited)

What issues would those be, that they don't have?

Since existing aero parts are serviceable, and the biggest issue that I see is just part count and a lot of pitch needed due to low RPM (or a lot of offset), which leads to large cosine losses.

If they do produce lift, then they can be used as wings?

Maybe the CoL is offset a lot? Offsetting parts is the main way to get around the low rpm

Edited by KerikBalm

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8 minutes ago, KerikBalm said:

What issues would those be, that they don't have?

Since existing aero parts are serviceable, and the biggest issue that I see is just part count and a lot of pitch needed due to low RPM (or a lot of offset), which leads to large cosine losses.

If they do produce lift, then they can be used as wings?

Not sure exactly what you mean by issues... the props do not suffer from the issue with regard to pitch and low RPM/offsets and cosine losses.
There would be nothing stopping you from sticking them on a craft and trying to use them as very small wings... though that was not specifically within their design parameters.

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1 minute ago, JPLRepo said:

Not sure exactly what you mean by issues... the props do not suffer from the issue with regard to pitch and low RPM/offsets and cosine losses.
There would be nothing stopping you from sticking them on a craft and trying to use them as very small wings... though that was not specifically within their design parameters.

Im not sure either, I was asking what you meant.

 

35 minutes ago, JPLRepo said:

They do not suffer the same issues as the existing lifting and control surfaces when you try to use the existing parts as propellers.

So how do these things work? What mechanics set them apart from the other lift producing aero surfaces?

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What he means with the usual issues is the centrifugal effect making the parts seemingly float around the hub at high rpm.

This is great, because those small props can also be used for turbines and/or building turbofans.

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44 minutes ago, Azimech said:

What he means with the usual issues is the centrifugal effect making the parts seemingly float around the hub at high rpm.

Where did you get this from.

He said:

1 hour ago, JPLRepo said:

The props do not suffer from the issue with regard to pitch and low RPM/offsets and cosine losses.

So my question is... How????

With rotors giving about 300 rpm under practical conditions (BG ec rotors spin well under the rad/s limit of the unity engine), a prop blade of a limited diameter/offset will have a rather low velocity.

This means that it must have high pitch to have positive AoA when moving forward at a decent speed. That pitch means that there will be massive cosine losses.

What do these do differently to get around that?

They always act as if they have a certain AoA and their lift vector always points perpendicular to the plane of rotation? This would be very funky and lead to weird and exploitable behavior if using them as wings...

Or is their CoL and CoD offset, so that they act as if the rotor diameter is much larger than it is? (2m radius for a prop isnt really enough for high speed with current rotors)

Is there any functional difference between the 2m prop blade and the 2m helo blade.

I want to be excited for these, but at the moment, I don't really understand what they do differently than what we have.

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2 minutes ago, KerikBalm said:

Where did you get this from.

He said:

So my question is... How????

With rotors giving about 300 rpm under practical conditions (BG ec rotors spin well under the rad/s limit of the unity engine), a prop blade of a limited diameter/offset will have a rather low velocity.

This means that it must have high pitch to have positive AoA when moving forward at a decent speed. That pitch means that there will be massive cosine losses.

What do these do differently to get around that?

They always act as if they have a certain AoA and their lift vector always points perpendicular to the plane of rotation? This would be very funky and lead to weird and exploitable behavior if using them as wings...

Or is their CoL and CoD offset, so that they act as if the rotor diameter is much larger than it is? (2m radius for a prop isnt really enough for high speed with current rotors)

Is there any functional difference between the 2m prop blade and the 2m helo blade.

I want to be excited for these, but at the moment, I don't really understand what they do differently than what we have.

Check the turboshaft topic, sort of parallel discussion about this.

 

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