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-   -   Forming aluminum for a cooling outlet fairing (https://vansairforce.net/community/showthread.php?t=83719)

Bob Axsom 03-10-2012 08:53 PM

Forming aluminum for a cooling outlet fairing
 
Gereed75 presented a fiberglass fairing that he made for the cooling air outlet that looks really good in a thread about exit drag. I would like to make one out of metal. It would have to conform to the radius of the cooling air outlet at the two corners. I can fill at the corners where the outlet turns out to blend in with the bottom of the cowl with fiberglass/resin/flox as necessary. One approach would be to make a wood forming block and beat it into shape. Another would be to fabricate it out of multiple pieces with no more than one bend on a part. And yet another way would be to build it out of fiberglass as Gary Reed did. Any good thoughts on how you would approach this?

Bob Axsom

hydroguy2 03-10-2012 09:13 PM

I'm on it Bob. I'll be at the hangar tomorrow attempting the same thing...out of metal.

Bob Axsom 03-10-2012 11:48 PM

Good Brian
 
I've got myself into a task with the American Cancer Society that is going to tie me up for a while. I have 650 pages of real time notes hand written into these little pocket notebooks that I have to copy and reproduce 4-to-a-page to accompany a lot of other material that I previously submitted. At my current rate is is going to take 33.5 manhours. Well back to work.

Bob Axsom

g zero 03-11-2012 09:41 AM

Order some 6061 type 0 from Air Spruce , 2x4 sheets or smaller are cheap to ship. This hardness is easy to work ( think lead soft ) . Scoops can be formed over PVC pipe . Wood tools can be custom cut on the band saw. A little practice and you be making wheel pants in no time !!

Bob Axsom 03-11-2012 12:37 PM

Great input (and I am laughing at your future thought)
 
I have bought a lot of aluminum from Aircraft Spruce over the years and I have more than enough left over for many of these farings but the easier to work with 6061 type O sounds very good. I'm just going to take a shot at thickness maybe 0.040".

Bob Axsom

paul mosher 03-11-2012 01:01 PM

English Wheel
 
English Wheel

Bob Axsom 03-11-2012 01:27 PM

I don't think so
 
I havd seen the work Jim Younkin has done on his english wheel and this seems like a different kind of work to me. I ordered two sheets of aluminum of "0" treatment/hardness... (they used to have more information in the catalog). One is 6061 bare 0.040 and one is 2024 alclad 0.032 - both are "0".

Bob Axsom

Omega232Devils 03-11-2012 01:39 PM

pretty easy
 
Hi Bob!
Gary has started an epidemic with this fairing! Haha. I talked to Gary a few weeks ago before this fairing picked up steam again. I made my first mockup out of cardboard, then used it to trace my pattern on scrap. 02 aluminum. I was going to use this as a test piece, but was too flimsy so I used the .02 piece to cut out .032 and formed that with some pliers, hammer and my work bench. Not pretty, but will allow me to test the fairing before permanent install.
Unfortunately I do not have test data as I had to rebuild a cylinder. Once I get the cylinder broke in I will test the fairing. My plan is to attached it with two screws into nutplates on bottom cowling and use speed tape to keep flush with fuselage for testing. If all goes well I will make a prettier one, paint it and permanently attach it.

Why alluminum? Because I have never glassed before. Otherwise I believe I would make it out of fiberglass.







Dan

terrye 03-11-2012 01:45 PM

Kent White
 
Kent White has lots of good stuff here on forming metal. Tools, videos, workshops:https://www.tinmantech.com/index.php

Bob Axsom 03-11-2012 03:50 PM

WOW! What Great Feedback
 
Paul Mosher I think I was too quick in dismissing the english wheel. You were probably right on the money I think after looking at the Kent White stuff Terrye referenced. There is a whole field of expertese that I never really appreciated. Finally, Dan that is exactly how I normally go about it except I use file folders (a box full usually lasts me a few years) to make my patterns. Using the soft aluminum that g zero recommended this should go well. I like the aluminum approach because of the heat involved - I will not rule out stainless steel if I need to go that way.

One way to interface the outlet of the cowl will be to step down the fairing/extension and run it inside the outlet and tie the two together with platenuts, flathead #8 screws and dimpled washers. I can pick up attach points on the bottom of the fuselage in similar fashion. Placement will be tricky to avoid foot contact problems. But if it doesn't work out I can just fill the dimpled holes with flathead screws. Let's see how many days until the 31st ...

Bob Axsom

P.S. Dan that looks pretty darn good to me.

g zero 03-11-2012 04:19 PM

You would be amazed at what you can form over wood blocks and other objects in the shop or the wife's kitchen. I have a small lathe and machined some plastic tips that I use with a rivet gun. Shirnkers and Strechers are great if you have them . We have and English wheel at work , I don't use it much as most projects are too small to work.

paul mosher 03-11-2012 05:08 PM

Pattern
 
What are you using for a pattern or did you make your own?

hydroguy2 03-11-2012 05:15 PM

Good job, Dan. Glad someone was able to get to the shop this weekend. I just got home from crappy day at work, so don't think I should taking out frustration on Aurora.

frazitl 03-11-2012 05:23 PM

welding
 
in case you end up wanting to weld to help create compound curves I suggest staying away from 2024. 6061, 5052, and 3000 series weld easily with the right equipment and skill (which I've observed, but have not yet developed BTW).

Still on my list.

gereed75 03-11-2012 07:38 PM

Dan Brian and Bob, Glad you guys are interested. I think that you will be pleased with the results.

I made my prototype set out of aluminum - I think 5052 1/4 hard (not sure what heat treat it was). It was soft enough to be hand formed. I made it in three sections - a left curved piece, a right curved piece and a center section. That way you could fit the two curved sides and make the center section as long as necessary to get the sides expanded and alined into a snug fit inside the stock cowl.

That looks like a pretty good effort Dan, and will certainly serve to check it out.

Sent my prototype out to Bob Mills. I guess he didn't know what a valuable piece he now owns!!

Good luck with it men and I'll help out if I can.

hydroguy2 03-11-2012 08:06 PM

I managed to get to the hangar after all and started roughing out the AL prototype. Should have a flyable version on Tuesday. I have a 4 pipe exhaust so will be different than others. Also looking up the lower cowl, I have a very restricted and cluttered outlet. 4 pipes, engine breather tube, exhaust hangars and heat muff in a opening smaller than factory cowl....I've got work to do.

Sorry about the lousy cell pic.

gereed75 03-11-2012 08:36 PM

Brian, also a good looking start. My first one fit inside the cowl, but for a prototype, you could use duct tape to seal the bottom and hold it in place for a try.

The only other drawback to an aluminum one is that, in my case, my transponder antenna is near the fairing. I flew with the aluminum fairing for about two months and did have one instance of "not receiving your transponder". I was at low altitude when it happened and suspect my antenna was blanked by the aluminum fairing.

Omega232Devils 03-11-2012 09:46 PM

Thanks
 
Thanks guys. Can't wait to test the fairing. I have a lot of CHT data as I have been working on my baffling to lower my CHTs. I think this fairing was originally a 'speed' mod, but I am doing it to lower CHTs by smoothing exit air. Any speed increase is BONUS!

Hopefully get some test data next week!

Dan

6 Gun 03-12-2012 06:18 AM

metal tools
 
Lots of cheap metal working tools at Harbour Freight english wheel and air hammer banshing tool and shrinkers and strechers.
Bob

rvmills 03-12-2012 10:12 PM

Quote:

Originally Posted by gereed75 (Post 638660)
<snip> Sent my prototype out to Bob Mills. I guess he didn't know what a valuable piece he now owns!!

Good luck with it men and I'll help out if I can.

Been focused FWF (a bit further fwd anyway) so far this winter, but will take some pics of Gary's proto-parts and post them when I get home from this trip.

Happy to share them as well!

Cheers,
Bob

hydroguy2 03-13-2012 03:09 PM

KHLN 131953Z 20022G33KT 10SM SCT100 14/M07 A2932 RMK AO2 PK WND 22034/1941 SLP938 T01441072

OK no test flying today for me.

But I'm getting the cowl outlet rough draft snipped out.


Something I'm wondering about is: My 4 pipe exhaust really fills the JamesCowl outlet in comparison to the larger Vans cowl. AND they hang below the cowl outlet and are uneven with each other. (also offcenter) So I'm contemplating cutting off about 1/2" of the exhaust pipes at an angle to get them out of the slipstream a bit. Anyone else modify the pipes to get them out of the breeze?

Bruce 03-13-2012 04:28 PM

Brian,
I have the 4 pipes but they are straight.
There is a pic on the Exit cowl thread.
Maybe that will help.

I think if you shorten them you will have
more turbulence on the bottom though.

My .05

hydroguy2 03-13-2012 05:12 PM

Thanks Bruce. Your pipe set up is different. I see you "A" model folks are dealing with a clogged outlet also, but looks like you have a lot more exit area.

I am trying to streamline the exit flow So thought trimming the pipes a bit might actually help and be less turbulence.

Here's a pic looking aft, you can see the PAX side hangs down more than the pilot side. Thought I could even them out a touch.

gereed75 03-13-2012 05:57 PM

Nice progress Brian

I am not sure what to think of the whole pipe thing. Mine angle and hang down significantly and I am considering shortening them and turning them back directly aft with a little angle connector Larry Veterman makes. Not sure yet. Using the oil drop method, I do see a small stagnation point directly aft and above my pipes. Oh well, can't get it all perfect.

I think that if the fairing and other cleanups work to smooth your exit airflow, you will find that your exit area will be more than adequate even with the four pipes. I am trying to think now of an efficient way to reduce my exit area without chopping up the cowl. See the next post.

Its always something

Mike S 03-13-2012 06:25 PM

Quote:

Originally Posted by gereed75 (Post 639372)
I am trying to think now of an efficient way to reduce my exit area without chopping up the cowl.

Airfoil shaped (flat on top, curved on bottom) after fairing on the bottom of the fuse-----fit it between the sides of your cowl extensions, depending on size and how far forward, you get to choke off the outlet, but at the same time give it a smooth ramp for the air to follow. Coanda stuff that Paul Lipps talked about, I seem to remember him posting a drawing of something like this.

You can also research stuff like it on the CAFE website------as I recall the guy who runs the CAFE foundation did this to a Mooney with good results. http://cafefoundation.org/v2/aboutca...oard.php#brien

More info for you techie types here. http://cafefoundation.org/v2/tech_en...greduction.php

RV8R999 03-13-2012 06:32 PM

Quote:

Originally Posted by gereed75 (Post 639372)
Nice progress Brian

I am trying to think now of an efficient way to reduce my exit area without chopping up the cowl.

Its always something

as per the discussion on Exit Drag


Mike S 03-13-2012 06:52 PM

More reading
 
http://cafefoundation.org/v2/pdf_caf...localflow2.pdf

Look at drawing C, it is depicting the airfoil ramp I was discussing a couple posts ago.

Ron Lee 03-13-2012 08:05 PM

Quote:

Originally Posted by Mike S (Post 639382)
http://cafefoundation.org/v2/pdf_caf...localflow2.pdf

Look at drawing C, it is depicting the airfoil ramp I was discussing a couple posts ago.

I can't access that file

gereed75 03-13-2012 08:07 PM

Mike, Can you get me to that link another way?? I'm getting the "forbidden 403" message. Thanks

Ken, That is looking good. I was thinking about something similar for my two pipe exit. I think I would like to tuck the pipes up and out of the airstream first. Then squeeze down the exit area from the bottom as you have done. ... and I thought I was done with this project!! It continues to morph.

hydroguy2 03-13-2012 08:55 PM

Well, got home from cowl fab work and the phone ran. Mike the hangarhome owner next door called and said the small old hangar is collapsing. I jumped in my truck to run out and check for other damage. the backwall blew out and sheared the posts. When it flipped over, part of the hangar went over the top to the next taxiway, landing next to my hangar. Debris field is about 300yards, but zero damage to anything else. Luckily no plane was in this hangar.

told you it was too windy to do testing. 60/60day. 60 degrees and 60mph

DanH 03-13-2012 08:58 PM

Quote:

Originally Posted by hydroguy2 (Post 639360)
.. you can see the PAX side hangs down more than the pilot side.

Yeah, yeah, a lot of guys have that problem ;)

gereed75 03-13-2012 09:29 PM

Yikes, As I read I was expecting something real bad!! Sorry for hanger owner, glad for you!

Bob Axsom 03-13-2012 09:55 PM

That is the right way to apply the curves for the desired effect
 
Quote:

Originally Posted by Mike S (Post 639376)
Airfoil shaped (flat on top, curved on bottom) after fairing on the bottom of the fuse-----fit it between the sides of your cowl extensions, depending on size and how far forward, you get to choke off the outlet, but at the same time give it a smooth ramp for the air to follow. Coanda stuff that Paul Lipps talked about, I seem to remember him posting a drawing of something like this.

You can also research stuff like it on the CAFE website------as I recall the guy who runs the CAFE foundation did this to a Mooney with good results. http://cafefoundation.org/v2/aboutca...oard.php#brien

More info for you techie types here. http://cafefoundation.org/v2/tech_en...greduction.php

That is what I was planning to do but when I went out to the hangar to visualize where I was going to mount things I decided it will not work unless I move the exhaust pipes down and then it is questionable. I did implement a version of that with the curve going the wrong way and it did look slick but slowed the airplane down. I'm doing OK right now and I haven't had a chance to work on the outlet fairing yet but i'm sure it will work if I alter the exhaust pipe position.



Bob Axsom

Jerry Cochran 03-13-2012 09:57 PM

Adjust?
 
Quote:

Originally Posted by hydroguy2 (Post 639360)
Thanks Bruce. Your pipe set up is different. I see you "A" model folks are dealing with a clogged outlet also, but looks like you have a lot more exit area.

I am trying to streamline the exit flow So thought trimming the pipes a bit might actually help and be less turbulence.

Here's a pic looking aft, you can see the PAX side hangs down more than the pilot side. Thought I could even them out a touch.

I have a 4 pipe with ball joints aft. If yours are the same, can't you adjust them to line up?


.

hydroguy2 03-13-2012 10:03 PM

I haven't tried lately, but recall when I was initially installing them, this is where they want to be. I figured it was better to support them in that position than to induce a stress problem. I'm pulling the lower cowl tomorrow, so I'll look again.

gereed75 03-13-2012 11:02 PM

Bob, Glad you put that picture in. I worked with it in paint to try to show where I think the fairing really does it's work.





The fairing gives the very slow, low energy, undirected air coming out of the sharp intersection corners a chance to get straightened out before the free stream airflow coming off the bottom and sides of the cowling mixes with it turbulently (is that a word??)

Not sure I described it right, but I'm sure you will get the message. The air coming out of the baffles under the cylinders flowing aft bangs into the firewall and is trying to find it's way out of that sharp corner and needs time to straighten itself. The simple corner fairing gives it that time.

My center body, bottom of firewall fairing and underbelly fairing probably all contribute a little, but this simple corner fairing gave me the bulk of my results.

That's what I think anyway.

Mike S 03-13-2012 11:37 PM

Quote:

Originally Posted by gereed75 (Post 639408)
Mike, Can you get me to that link another way?? I'm getting the "forbidden 403" message. Thanks

I put it up the only way I know how to do it.

You could try searching for "CAFE Foundation" in Google or some such, then click on the "Research" button, then in the drop down menu, go to "CAFE Reports" and then to "Local Flow 2" in the list of reports.

It is a PDF, maybe that is why you can not see it???

RVnoob 03-13-2012 11:41 PM

Quote:

Originally Posted by Mike S (Post 639463)
I put it up the only way I know how to do it.

You could try searching for "CAFE Foundation" in Google or some such, then click on the "Research" button, then in the drop down menu, go to "CAFE Reports" and then to "Local Flow 2" in the list of reports.

It is a PDF, maybe that is why you can not see it???

try this link:

http://www.cafefoundation.org/v2/pdf...localflow2.pdf



(somehow you need the www in the front of the URL)

Mike S 03-13-2012 11:51 PM

Quote:

Originally Posted by RVnoob (Post 639465)
try this link:

http://www.cafefoundation.org/v2/pdf...localflow2.pdf



(somehow you need the www in the front of the URL)

That gave me the forbidden message.

Bob Axsom 03-14-2012 01:44 AM

I got the forbidden message as well
 
Coanda effect is a pretty simple concept and if you just want the general idea of what it is a Google search will do it for you. Does anyone remember the Boeing YC-14? It was in a STOL cargo aircraft competition with the McDonnell Douglas YC-15 It had its two engines mounted high to exhaust over the upper surface of the wing and follow the deployed flaps and generate lift. The MDC entry directed the exhaust from its four engines under the wings directly against the deployed flaps to generate lift.

Gary the air coming through my cylinder cooling fins never sees the firewall because of my baffle configuration in the lower cowl. I think your fairing does what you describe and more. I don't know if you have ever met Alan Carroll but he is one smart dude also (like you) with a fast RV-8. You may recall earlier he mentioned he extended the cowl at the bottom of the outlet which is the other thing your fairing does. If you think about it the air mass in the lower cowl has some downward force in the stock configuration and the outlet being chopped off at the firewall does not eliminate that. I can imagine an inverted rooster tail of air or a burbling directionless mass coming out of there but your and Alan's fairing's turn it and give it some direction aft. in addition to your side barriers. It will be interesting to see what Dan and Brian report when they get to fly their fairings.

Bob Axsom


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