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-   -   a couple printed ideas (https://vansairforce.net/community/showthread.php?t=147771)

Steve Melton 03-26-2017 05:51 PM

a 7 degree taper is typically a good free stream diffusion angle for maximum pressure recovery. I don't know the wheel pant's angle. the nose needs to be fairly large to allow the plastic ample area. the alum part from JD can be thinner.

note: I did a check fit on a neighbor's RV-4 that has a significant proseal build up around the flange to wing skin and the fairing would not fit flush. I will make a custom enlarged flange recess area for his.

one flight test today had positive result, light rain. the fairing was secure.



avgas test. after one hour it was same as before testing. we will leave it for a week. ABS plastic.


Steve Melton 03-26-2017 06:02 PM

Quote:

Originally Posted by 1001001 (Post 1160799)
Steve,

I love what you're doing with 3D printing.

A few years ago (nearing 10!) I started fiddling around with CFD analysis. I was working in the power industry at the time and was looking for ways to analyze and improve the operation of some equipment I was responsible for. I built a CFD box out of what was at the time some awesome hardware and ran OpenFOAM on it.

Fast forward, I am in a new job that doesn't have the same concerns and have left CFD behind, but not the desire to play around with it. I might consider re-equipping and getting up to speed with OpenFOAM again. I understand it has advanced quite a bit since the old days.

Now being into airplane building I have thought a lot about the possibilities for customized 3D printed solutions for fairings and covers and such, and the ability to test them out in a CFD environment. What have you found about the capabilities of SolidWorks for CFD? Does it approach the capabilities of the dedicated CFD packages?

I thought the EAA version of Solidworks had CFD analysis but it does not. There are two different versions of student Solidworks. EAA has the lowest version that does not include CFD.

rocketman1988 03-27-2017 09:28 AM

ABS and Gasoline
 
Here is an engineering reference on chemical resistance:

http://www.gilsoneng.com/reference/ChemRes.pdf

Checking ABS and Gasoline yields a rating of 3 which means it is not recommended. Hate to see that really nice 3D printed part melt into a pile of goo...

Print it in Nylon, it has great gasoline resistance and is 3D printable...

Steve Melton 03-27-2017 10:37 AM

Quote:

Originally Posted by rocketman1988 (Post 1161059)
Here is an engineering reference on chemical resistance:

http://www.gilsoneng.com/reference/ChemRes.pdf

Checking ABS and Gasoline yields a rating of 3 which means it is not recommended. Hate to see that really nice 3D printed part melt into a pile of goo...

Print it in Nylon, it has great gasoline resistance and is 3D printable...

after soaking for a week, we may find a pile of goo at the bottom.... or not. :)

donaziza 03-27-2017 10:56 AM

First--your "subject" matter before the 3D printer.
 
I've been following this 3D printing thread with great interest, having never known anything about it before. I've Googled enough where I've got the concept of how the "printer" works and what you can do with it, but I can't seem to really find anything on Google, that explains how to get the "concept" either from your head, or from an actual object "Whatchamajinger" you want to reproduce into the printer's computer, so that the printer knows "what to print"?:confused:

Like Steve Melton, you made that scoop, others were talking about making antenna's---between the idea in your head, and actually creating it on the printer, what happens, and how do you do it?

rv8ch 03-27-2017 02:02 PM

Solidworks
 
Quote:

Originally Posted by donaziza (Post 1161091)
I've been following this 3D printing thread with great interest, having never known anything about it before. I've Googled enough where I've got the concept of how the "printer" works and what you can do with it, but I can't seem to really find anything on Google, that explains how to get the "concept" either from your head, or from an actual object "Whatchamajinger" you want to reproduce into the printer's computer, so that the printer knows "what to print"?:confused:

Like Steve Melton, you made that scoop, others were talking about making antenna's---between the idea in your head, and actually creating it on the printer, what happens, and how do you do it?

It seems a lot of people are using Solidworks, which if you are an EAA member, is "free".

https://www.eaa.org/en/eaa/eaa-membe...esource-center

It's a kind of 3d drawing program. Be psychologically prepared to invest some time learning it if you are not already used to CAD programs.

rocketman1988 03-28-2017 11:21 AM

Interesting on the Gas test...
 
That is really interesting that gas doesn't seem to be affecting the
ABS. Let us know after a week...

One thing I did find out about ABS is not to get blue loctite on it. I 3D printed an arm for my flap position sensor and used blue loctite to secure the ball for a ball and socket attachment. Less than a week later, the ABS literally crumbled in my hand...then I read the warning label on the loctite...:D

Snowflake 03-28-2017 05:51 PM

Quote:

Originally Posted by Steve Melton (Post 1160860)
a 7 degree taper is typically a good free stream diffusion angle for maximum pressure recovery. I don't know the wheel pant's angle. the nose needs to be fairly large to allow the plastic ample area. the alum part from JD can be thinner.

Here's a quick model done with TLAR measurements... "sort of" to the shape of the PR wheelpant. A piece of double-sided 3M Body Molding Adhesive tape
front and back, and it would stick nicely. Tape at either end and none in the middle would also help account for the curve of the bottom of the wing... The tape is about 3/32 thick.

https://lh3.googleusercontent.com/wZ...PRks4XiQk?.jpg

https://lh3.googleusercontent.com/QC...YXze8VQ8M?.jpg

https://lh3.googleusercontent.com/d_...q9Yezzvow?.jpg

Steve Melton 03-28-2017 08:04 PM

Rob, trying to incorporate your ideas tonight before releasing it to the group. I think it looks better. I can't see your pictures.






Snowflake 03-29-2017 07:45 AM

Sorry, complain to Doug for not allowing photo uploads. I already have.

Here's a link to a Google Photos Album, which should be visible to all:
https://goo.gl/photos/819NY1dPewsJaNkG6


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