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

Steve Melton 03-29-2017 08:24 PM

Rob, I like the concept. Looks like a Lancair. This one is more 70'ish.

after 3 days soaking. note the color change. strength test by hand, I didn't notice anything. seemed to be original in shape and was not affected at the surface. go figure. I like it. ABS plastic. returned to the avgas for another four days.



new shape




RV-4 03-30-2017 09:32 PM

FUEL DRAIN FAIRINGS
 
Hi Steve

Do you have a plan to sell some of these nice looking fairings??

If you do, I'll take a set...

I bought the one from JD Airs but they don't quite fit...The fuel drains on my RV-4 have a cork gasket between the wing and the little white roundel and they are too deep for JD Air fairings to fit against the wing...so yours might be the solution.

Let me know if you do sell some.

Cheers

Bruno
rv4@videotron.ca

Steve Melton 03-31-2017 04:07 AM

my neighbor has an RV-4 that is similar and will require a special fit fairing because of the gasket but it will be fine. we will do a test fit on his and get some pictures. because the fairing was designed using academic Solidworks we cannot sell them commercially. I will make a parts list (3 parts) and instruction how to assemble (one minute) and supply the .stl model. you can have them printed anywhere, even UPS. just send them the file by email and have them print you a couple. this would be a simple fun assembly project for local EAA chapters. also, I'll have a box of them under my wing at Oshkosh for taking, mat'l cost = $3 a pair.

humptybump 03-31-2017 04:33 AM

Steve, have you played with acytone vapor smoothing?

Steve Melton 03-31-2017 04:58 AM

I tried it once on part made from PLA but didn't like the results. my technique was poor. I like the printed look. the print lines for this part are predominantly in the direction of flow so I don't believe you would gain much efficiency but then again every bit helps.

Weasel 03-31-2017 05:09 AM

Nice work there Steve
 
while you are at it might should do this one.....:p

], on Flickr

Weasel 03-31-2017 05:10 AM

Quote:

Originally Posted by Steve Melton (Post 1162096)
I tried it once on part made from PLA but didn't like the results. my technique was poor. I like the printed look. the print lines for this part are predominantly in the direction of flow so I don't believe you would gain much efficiency but then again every bit helps.

Try is on ABS. :)

Steve Melton 03-31-2017 05:13 AM

:), and maybe here for this draggy thing. looking at the photo, maybe use an access panel screw behind to secure? it may not be in-line but if is then maybe slide the plastic fairing over the ball then move it aft to lock on the ball and secure with a panel access screw? and BTW, the tie down ball is also a good jacking point, I always leave it on.


humptybump 03-31-2017 05:47 AM

Quote:

Originally Posted by Weasel (Post 1162099)
Try is on ABS.

Yes. Acytone vapor smoothing only works on ABS. Acytone will dissolve ABS.

I don't know what effect it has on PLA.

daddyman 03-31-2017 06:43 AM

Very cool
 
Quote:

Originally Posted by Steve Melton (Post 1162091)
my neighbor has an RV-4 that is similar and will require a special fit fairing because of the gasket but it will be fine. we will do a test fit on his and get some pictures. because the fairing was designed using academic Solidworks we cannot sell them commercially. I will make a parts list (3 parts) and instruction how to assemble (one minute) and supply the .stl model. you can have them printed anywhere, even UPS. just send them the file by email and have them print you a couple. this would be a simple fun assembly project for local EAA chapters. also, I'll have a box of them under my wing at Oshkosh for taking, mat'l cost = $3 a pair.

Steve,
I too would like to download and have printed your cool go fast thingie.

How do you mount it?

Davddyman
dues + paid

Planecrazy232 03-31-2017 06:48 AM

I have a buddy with a printer. If you are sharing the file it would be appreciated!! agrecojr at comcast dot net

AAflyer 03-31-2017 04:23 PM

WoW!
 
Those HAVE to be about 5 knots, RIGHT?!! ;)
JK, I'm jealous of your capabilities.
Some day, the entire 'Quick-build" fuselage will be printed, I guess.:D

Weasel 03-31-2017 07:27 PM

Idea
 
Quote:

Originally Posted by Steve Melton (Post 1162100)
:), and maybe here for this draggy thing. looking at the photo, maybe use an access panel screw behind to secure? it may not be in-line but if is then maybe slide the plastic fairing over the ball then move it aft to lock on the ball and secure with a panel access screw? and BTW, the tie down ball is also a good jacking point, I always leave it on.



http://www.vansairforce.com/communit...=139792&page=3

Just a thought
Quote:

Originally Posted by Weasel (Post 1094881)
Aluminum Angle is your friend

You could also use a round head bolt



Steve Melton 04-01-2017 09:12 PM

fuel test
 
fuel test after 6 days soaking. texture is the same as original. no particles in the fuel jar after several minutes of shaking. pull test the insert to the point where the .032 wire stretched and failed. placed the fairing back in the fuel. so far the fuel does not appear to be affecting the fairing. plan to conduct another pull test after more soaking.





this one was not soaked and also failed the wire. I am planning for a creep test on the insert by applying a constant weight over time.

Steve Melton 04-01-2017 09:20 PM

thread lock test
 
I applied several thread lock types to the fairing and found that MXlock affected the ABS. So far the others did not.

failed test


I will pull these this one after soaking but I don't expect good results.



these seem OK after several hours but will have better results after several weeks. I also tested RTV but don't have photo. Initially it didn't appear to have any reaction.



Steve Melton 04-01-2017 09:30 PM

set screw
 
I used the nylon tipped set screw but I was able to twist the fairing on the drain boss with some effort. The friction coefficient is low with the nylon tip and ABS to the alum. I don't believe the nylon tip set screw is a viable option. there is minimal force on the fairing to lift it off but over time it may. I believe it is better to use the set screw without the nylon tip to the alum boss. there is not much land on the boss and the fairing set screw is moved upwards as far as possible to allow for the plastic insert nut. for added attachment strength, some RTV or other adhesive on the fairing may be beneficial.




Steve Melton 04-01-2017 09:46 PM

stress analysis
 
this model does not accurately represent the printed part because I cannot model the internal hollow-hatch print but it is close for the areas where the set screw and boss are located because those are mostly solid.

a quarter turn on the 32 pitch thread set screw = .008 inch deflection and allows the fairing to maintain enough clamp thru 130F temperature delta. say you install at -30F and fly to 100F. the plastic will expand 5x the aluminum but you will still have .004 inch deflection clamp on the fairing. ABS is quoted as being creep resistant so I believe it will not relax and will maintain the clamp over time but some additional adhesive may be beneficial.

for installing, one quarter turn of the set screw after contact is the optimal value for clamp and minimizing stress in the plastic part.

some pretty pictures from my Mecway home analysis.

axial displacement


vertical displacement


overall displacement magnitude


von Mises stress


axial Principle stress


reaction force magnitude

Steve Melton 04-01-2017 10:00 PM

printing
 
a print photo


Steve Melton 04-02-2017 08:36 PM

more pull test
 
as expected the MxLock 42 does not play well with ABS but the other thread lock was fine from a strength point.

MxLock 42 coated insert failed at 10 lb pull


the penetrating Locktite 290 and RTV were fine and broke the .032 wire upon pull testing.



I didn't pull the VC-3 yet but it appeared to have the best adhesion and did not damage the ABS surface nor did it become hard. this is the same thread lock I use for plexiglass and if the pull test is successful it will be my thread lock of choice for ABS.

VC-3 appears to be very good for ABS. a series of pull tests still pending.


the avgas soaked fairing pull test was repeated with success determined by failing the .032 wire. no deterioration of the fairing was evident. I returned it to the avgas for another week.

Steve Melton 04-02-2017 08:50 PM

build method
 
parts:
- ABS printed fairing, mine are printed as such: layer thickness = .2mm, 5 bottom layers, 4 side layers, 4 top layers, 35% infill
- 8-32 heat set insert for plastic, mcmaster carr
- 8-32 x 5/16 set screw, mcmaster carr or Ace hardware






remove support material


clean inner hole with #4 drill bit


clean outer hole with 1/4 inch drill bit, take caution to only clean to shoulder of the inner hole


heat the brass insert for 10-15 seconds (I used a small butane torch) and push it in as straightly as possible. ABS will become soft at 340F (170C) so the brass inserted does not require too much heat. If the insert is too hot it will damage the plastic.


you may have some plastic extrude from the end. use a pick and it will easily be removed.


you may have a slight bulge from on the upper surface because on the insert. cut that away with a knife.


file the top smooth to remove an remaining support material


finished, ready for install. one quarter turn of the set screw is recommended after contact.

Steve Melton 04-02-2017 09:14 PM

fairing file
 
I sent the file to those I had email addresses.

if you need one send me an email to se melton 500 @ g mail .com

my yahoo account doesn't allow .stl files to be sent for some reason.

Snowflake 04-05-2017 05:36 PM

Here's a photo of my first prototype using the "pressure recovery" profile. The fuel drain and JD Air fairing are included for size reference.

This was printed with PLA, 0.4mm nozzle, 0.1mm layer, "Light" infill.



Another View for reference:


Steve Melton 04-05-2017 08:27 PM

nice design.

give the plunger plenty of clearance.


Snowflake 04-05-2017 11:26 PM

This is quite close to the plunger, and I do plan to make it a little larger. But I wanted a tight fit so it would prevent air leaks. I think i've got to make another one anyway, as I think the step inside for the hex on the plunger is not deep enough. Easy to fix and re-print though!

I wonder if it would be possible to install one of those melt-in inserts from the *inside* of the opening, and have a smaller hole out to the front for the set screw and hex key. That way, when you tighten the set screw, it wants to push the insert further into the plastic, rather than push it out. What surface does your set screw bear down on? One of the flats on the drain? Or the aluminum shaft on the flange?

larosta 04-06-2017 12:35 AM

An insert for installing on the baskside of plastic parts
 
Take a look at these

"Install on the underside of your material. The flange keeps the insert from being pulled through a hole. Installing a screw from the top of the material causes the insert to expand and drives the knurls into the surrounding plastic to keep it secure."

https://www.McMaster.com/#92395a324/=172po2f

YvesCH 04-06-2017 06:13 AM

My parts arrived and most of them work great! Except the holder for the CO-monitor was designed a bit to weak and I have to increase the wall thickness. But for a first try I am more than happy!



Ist only a trial, the locking washer are missing on the bus bar and there are not all cables installed yet. I will wrap the cabled with Silicon wire before I zip-ty them permanently. Also the essential bus diode will be in shrinking tube on the final version. But it looks quite good I think.











Steve Melton 04-06-2017 06:14 AM

Quote:

Originally Posted by Snowflake (Post 1163633)
This is quite close to the plunger, and I do plan to make it a little larger. But I wanted a tight fit so it would prevent air leaks. I think i've got to make another one anyway, as I think the step inside for the hex on the plunger is not deep enough. Easy to fix and re-print though!

I wonder if it would be possible to install one of those melt-in inserts from the *inside* of the opening, and have a smaller hole out to the front for the set screw and hex key. That way, when you tighten the set screw, it wants to push the insert further into the plastic, rather than push it out. What surface does your set screw bear down on? One of the flats on the drain? Or the aluminum shaft on the flange?

it installs on the alum boss. the set screws needs to located at the upper most.

YvesCH 04-06-2017 06:24 AM

Quote:

Originally Posted by Snowflake (Post 1163633)
This is quite close to the plunger, and I do plan to make it a little larger. But I wanted a tight fit so it would prevent air leaks. I think i've got to make another one anyway, as I think the step inside for the hex on the plunger is not deep enough. Easy to fix and re-print though!

I wonder if it would be possible to install one of those melt-in inserts from the *inside* of the opening, and have a smaller hole out to the front for the set screw and hex key. That way, when you tighten the set screw, it wants to push the insert further into the plastic, rather than push it out. What surface does your set screw bear down on? One of the flats on the drain? Or the aluminum shaft on the flange?

You could also make a hexagonal opening in the inside to put a nut in there. then the nut would be pushed against the part when you tighten it to the Plunger. attached a quick sketch :)

Weasel 04-06-2017 06:49 AM

Quote:

Originally Posted by YvesCH (Post 1163658)
My parts arrived and most of them work great! Except the holder for the CO-monitor was designed a bit to weak and I have to increase the wall thickness. But for a first try I am more than happy!

Nice. That's crispy right there

Steve Melton 04-06-2017 04:06 PM

Quote:

Originally Posted by YvesCH (Post 1163658)
My parts arrived and most of them work great! Except the holder for the CO-monitor was designed a bit to weak and I have to increase the wall thickness. But for a first try I am more than happy!



Ist only a trial, the locking washer are missing on the bus bar and there are not all cables installed yet. I will wrap the cabled with Silicon wire before I zip-ty them permanently. Also the essential bus diode will be in shrinking tube on the final version. But it looks quite good I think.











beautiful. you are taking wiring and tube routing perfection to another level.

no wonder, you're from Switzerland. Basel, no less, the home of the tennis Legend.

my mother in-law is from Switzerland. her house is very clean.

Snowflake 04-06-2017 06:25 PM

Quote:

Originally Posted by YvesCH (Post 1163661)
You could also make a hexagonal opening in the inside to put a nut in there. then the nut would be pushed against the part when you tighten it to the Plunger. attached a quick sketch :)

Yep, already thought of that, and am working on it. I was even thinking about having the printer stop part way
through the print, dropping the nut in, and then printing in over top of it... But then you could never change it
if you cross-threaded it by accident... :P

With the slot for the nut like this (below) once the set screw is in place neither the set screw nor the nut can
fall out as long as the screw is in the nut. Just need to get some nuts and set screws in-hand and then I can
final-size the features and print the next iteration.

DaleB 04-06-2017 09:49 PM

Sigh... you guys are going to cost me money yet. Every time I talk myself out of buying a 3D printer you go and post stuff like this.

Steve Melton 04-07-2017 02:13 PM

ABS creep testing
 
the recommended torque on the set screw for this fairing = 1/4 turn but what happens if it is turned four times that amount? answer, not much. part remained secure and tight. no reduction of torque on set screw ( by feel ). plastic insert nut remained secure. no visible damage. no change in part appearance pre and post test. part returned to original dimensions. there was some visible set screw contact marks on the steel.

1.5 week creep test at room temperature with a full turn of the set screw after contact. mounted on steel conduit. a fresh fairing, not fuel soaked.
















Steve Melton 04-07-2017 02:21 PM

VC-3 thread lock pull test
 
as expected good results for insert pull test using VC-3 thread lock. this is the same thread lock used for my screws on the plexiglass. do not appear to affect ABS plastic and has excellent adhesion. to date I have not used any thread lock for flight testing this fairing ( a couple weeks ) and have had no loosening but it may be beneficial for long term install.

two pull tests





Steve Melton 04-07-2017 02:28 PM

more fuel testing
 
this fairing is going on three weeks of fuel soaking and pull testing to failure of the .032 wire on the insert ( 5 tests ). it does have some clamp marks from the vise but no chemical affects. it has been placed on the torture pipe for creep testing. it previously had a week of having a 35 lb load hung on the insert with no adverse affects. so far it is holding up fine.




lr172 04-07-2017 03:02 PM

Steve,

Any chance of you sharing your design/file for these fairings? I was going to make some of these from composite, but I imagine that I can find a local friend with a 3D printer.

Larry

Steve Melton 04-07-2017 03:30 PM

if you need one send me an email to: se melton 500 @ g mail .com

my yahoo account doesn't allow .stl files to be sent for some reason.

I've sent these around to scores all over the world (which is cool). you can have them printed anywhere, even UPS.

- ABS printed fairing, mine are printed as such: layer thickness = .2mm, 5 bottom layers, 4 side layers, 4 top layers, 35% infill

the material costs for a pair of these = $3. that includes printed fairing, nut inserts and set screws.

PilotjohnS 04-07-2017 03:44 PM

science
 
What great science. I cant believe you went to all this trouble. Shows everyone your love for aviation.

Now the next challenge is to model these in CFD and see how many knots they are worth at 8K and 180 kts? Anybody up for the challenge? or maybe in flight comparison tests before and after. I am really curious if they are noticeable. Even 2 knots is worth it.

keep up the good science.

Steve Melton 04-07-2017 03:50 PM

this is called a "Houch" for Walt Houchens. an incremental improvement.

lr172 04-07-2017 10:12 PM

Quote:

Originally Posted by Steve Melton (Post 1163965)
if you need one send me an email to: se melton 500 @ g mail .com

my yahoo account doesn't allow .stl files to be sent for some reason.

I've sent these around to scores all over the world (which is cool). you can have them printed anywhere, even UPS.

- ABS printed fairing, mine are printed as such: layer thickness = .2mm, 5 bottom layers, 4 side layers, 4 top layers, 35% infill

the material costs for a pair of these = $3. that includes printed fairing, nut inserts and set screws.

Thanks Steve. I'll send an email. Are the above details that my friend or firm that I pick will need to print these?

Larry


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