Openvsp design inlet

[seungkyu joung]

Hi i’jay from korea 

Thanks very much your effort 

Do you have any example sketch naca inlet wing surface? 

Or how can i loft / remove from other part

I love openvsp !!!

Thank you 

Best regards 

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[Brandon Litherland]

Are you asking how to remove material for a NACA Duct? https://en.wikipedia.org/wiki/NACA_duct

There are some ways that require a bit of effort but you should start by modeling the negative volume of the duct and then either running CompGeom or Trimmed Surfaces to export the cut geometry.

[Rob McDonald]

OpenVSP is a conceptual design tool.

I like to describe the output of conceptual design as a "Yes/No decision from leadership whether to continue the program".

This is not just a cheeky phrase -- it is to remind us that our job is to improve the quality of that yes/no decision.  When adding details to a model, we should ask ourselves -- does including this detail in our conceptual design process have an effect on the yes/no decision?  If that answer is no, then we should not include the detail.

Sometimes details matter, sometimes they don't.  There is not one always correct answer.

However, it would be very unusual to worry about including a NACA inlet in a conceptual design model.

Why do you think you want to do this?

Rob

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[seungkyu joung]

Hi rob

Thank you very much

For your kind advice 

I’m very beginner , openvsp very helpful for me, us to quickly and review 

Best regards jay

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[seungkyu joung]

In case, about inlets 

It just example for loft, remove from surface

The aircraft configurations are very different and many type will design in conceptual design phase 

Times are changing rapidly

Someone want to design large duct into wing surface, through fuselage 

Thank you very much :-)

Best regards jay

On Sat, May 14, 2022 at 1:33 AM Rob McDonald <rob.a.m...@gmail.com> wrote:

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[Rob McDonald]

In the case of an aircraft with a buried engine -- then yes, representing the flowpath in some way is likely important (as opposed to a small electronics cooling inlet etc.).

The negative volume approach described by Brandon is the best way in this situation.

Rob

[seungkyu joung]

Thank you for your advice 

I will try It :-)

Best regards jay

To view this discussion on the web visit https://groups.google.com/d/msgid/openvsp/30f3b104-0811-415a-a730-10edf5c2f520n%40googlegroups.com.

[seungkyu joung]

Thank you for your response

It was very helpful

Thank you 

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[seungkyu joung]

Hi all, 

here are some examples of what we will sketch.

i hope, openvsp can quickly sketch these shapes. 

 

2022년 5월 16일 (월) 오전 8:11, seungkyu joung <nskj...@gmail.com>님이 작성:

[Brandon Litherland]

You can model these types of features but without a great deal of effort you'll have to export to CAD to capture the geometry accurately.
To get a "real" NACA duct punching a hole through a body, the geometry has to follow the 3D curve of the intersection between a cylinder with the same radius as your duct and the wing upper and lower surfaces.  From there you have to decide if you want a scaled NACA profile all around the intersection relative to the thickness of the wing e.g., the NACA duct would have a variable chord all the way around, or keep a fixed profile all the way around (simpler).  

In any case, you can approximate these with stack components and skinning and make this cutter geometry a negative volume under the Gen tab.  If you really want close to a NACA profile, you can use Fit Model to find the skinning combination that will get you there.  However, even though you can run something like this in VSPAERO's Panel mode, you'll need experimental data of such a configuration to ensure that the results are correct.

[seungkyu joung]

I’m jay thank you very much great response 

I will try it, but negative volume is little difficult 

Can we(openvsp)add a function that can be applied simply to the next release?

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[Brandon Litherland]

Here are links to my presentation and recording from the 2021 OpenVSP Workshop regarding Trimming with Negative Components.

There is not currently any development track to make modeling these features easier in VSP.  I'm generally able to trick VSP into doing what I want because I'm very familiar with the capabilities and functions but that doesn't mean it's the right way to go about the process.  I think at the time of the workshop Rob equated some of these to David Letterman's "Stupid Pet Tricks".  Just because you CAN do something in OpenVSP doesn't mean that you SHOULD.  For detailed features like this, CAD is really the better way to go.  Ducted or buried inlets are model features that aren't really meant for the analyses in VSP because VSPAERO specifically is an inviscid, potential code albeit with some viscous correction and stall modeling.  For these you're likely looking at mid- to high-fidelity CFD to capture what's really going on.  If you don't have access to CAD and still need to make something approximate for your gridding and CFD tools, then as I said VSP can do a good job of approximating the surfaces.  But, no, it won't be easy.

As for adding things to VSP, new features almost always come directly from funded work under NASA, DoD, or Industry contracts where a clear desire for certain capabilities is expressed.  It takes a LOT of work to add capabilities or features that may seem relatively simple at first glance.  Sometimes, just because he is nice, Rob will add or improve features in VSP on his own free time but that is understandably limited.

My recommendation is to spend some time working on the model to see what works and what doesn't.  Try cutting material away with Negative Volume and see if you can't get something that looks right.  I've included an image of the geometry I made this morning before work to give you an idea of how I modeled it.

[seungkyu joung]

dear brandon

Thank you for your kind and detailed reply.

All understood.

We inquired about the possibility of adding these functions because they are likely to appear frequently in the future at the conceptual design stage.

Limitations: When I looked at the conceptual design papers using vsp hanger and openvsp, I felt that most sketch shapes could not escape these limitations.

Diversity: The keyword VTOL has now become a common anticipation that everyone is discussing, and if you search for VTOL in Google, you will find numerous types of aircraft.

Rights: Jets, rockets, unmanned aerial vehicles, and drones are all aircraft that share the sky, and I think they are all important in this day and age.

VSP : vehicle sketch pad

Thanks to NASA and the contributors for the disclosure.

best regards Jay

2022년 5월 20일 (금) 오전 12:10, Brandon Litherland <litherlan...@gmail.com>님이 작성:

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