[Charles in SC]

I am building a -7. I have been studying my up coming baffle job and am wondering if anyone has ever tried making the baffles out of something other than aluminum such as carbon steel or stainless in the oil cooler area to prevent cracking. I am kind of thinking out loud hear. I know that most lawn mower engines have steel baffles and they endure a lot of shaking and stress. Any thoughts?

 

[lr172]

experience seems to indicate that the Van's baffle structure is relatively robust if you heed some of the warnings, advice, ideas on this site. The #4 corner holding the oil cooler can be successfully reinforced to last 1000's of hours, based upon many posts I have read. Suggest you search for some of the reinforcement/bracing ideas. If you're considering making your own, I would research this as well. I have read a few posts talking about the work involved with the old baffle kit vs new. And that was still partially pre-fabbed. Your making a LOT of work with only limited benefit.

Larry

 

[BillL]

Research says this will work to overhaul.

I would agree others have made this work. Do some study and look your self. There are three areas for reinforcement on the parallel valve with the standard vans cooler. Niagara 20002a. 1. The vertical interface at the LR corner - add an angle 2. A structural tie from the top of that angle to the upper forward baffle screw on #4, and 3. some tie back from the center, RS of the cooler back to the head or case. I did mine back to the head with an extended rocker screw.
#1 & #2

#3

 

[JonJay]

In addition to the three areas Bill shows, another area of concern is the "jog" inboard of the cooler. I followed all precautions, extra angle, brace, etc... and a crack still formed on the inside corner starting at the top of the baffle and moving down towards where the Cleko is shown on Bill's picture.
I ended up reinforcing this corner with a piece of .032 bent to match the profile of the jog and keeping bend radius in mind. That took care of it.
It is very easy to add this reinforcement later. Just watch that corner as we are moving the stress somewhere.

 

[Raymo]

My engine came with some baffling that is .063 thick. Very sturdy and still lighter than making it from steel.

 

[bret]

I went with Paul Ds thinking of if you can lift the plane by the oil cooler, it may be strong enough, I did like the photo but used .125 3/4 angle and then also to the center case bolts, triangulated the hole thing. Also, the new baffle kit has a different material at the cooler mount area?

 

[rzbill]

The fuselage J-Channel across the back baffle wall I installed has been completely satisfactory on my parallel valve with standard vans cooler. 535 hrs, no cracks so far.

Pictures in the post noted below.

Post in alternate thread

 

[JonJay]

I went with Paul Ds thinking of if you can lift the plane by the oil cooler, it may be strong enough, I did like the photo but used .125 3/4 angle and then also to the center case bolts, triangulated the hole thing. Also, the new baffle kit has a different material at the cooler mount area?

Bret - I know they changed some things about the baffle design, like the formed piece that allows the back of the baffle to be one straight line avoiding the messy jog back. Us early builders had to form this part ourselves, or deal with it with the small pieces of baffle material. Not fun. I am not sure about material or thickness changes, but they certainly where not anodized like Bill's beautiful pieces.

The other common related issues where oil cooler flange cracks. I reinforced the flanges with .063 angle, front and back on both sides. The angle simply acts like a washer and spreads the load across the oil cooler flange. The angle is drilled in assembly and mounted through the same mounting bolts as the cooler. Very easy to do this. Additionally, I used baffle material like a gasket between the oil cooler mounting flange and the baffle. The idea going around at the time was this provided an insulator for heat transfer between the cylinder, baffle, and cooler. Not sure how necessary this was, but I have had no oil cooler flange cracks and my oil temps have always been on the low side.

I too chose the center case bolt as an anchor point for the brace as well. At the time, there was an argument about cylinder head movement and bracing to the cylinder. Not sure anyone lost or won that argument, but the center case bolt was a natural and easy location to brace from, so, there ya go.

 

[Michael Burbidge]

Brace material...

Hey Bill,

What kind of material did you make the round brace out of? Where did you get it? Did you heat it to shape the ends?

Thanks,
Michael-

 

[A5555]

I did this as a new build 500 hrs ago using a hollow piece of alum tube and crudely squashed on the ends. I chose not to connect directly to the engine but higher up on the baffle thru the angle. no signs of distress in anything as of yesterday. no other reinforcements. a machined piece of alum or a steel tube is a better design but mine is lighter.

 

[BillL]

Hey Bill,

What kind of material did you make the round brace out of? Where did you get it? Did you heat it to shape the ends?

Thanks,
Michael-

It is a rod 5/16 cold rolled steel - it is what I had
Heated the ends with a MAPP gas torch and beat the ends flat hammer on rail. I made a template from thin aluminum to get the holes perfect. It is a 90 deg angle between the surfaces but easier to make a template. It took several template tries for hole location perfection. Then set the template on a square to measure the X-Y dimensions and used the marked square as the jig for making the final part hand forged part. It really did not take very long. Not too elegant, but it is small and should work. Maybe nicer and lighter if aluminum, but didn't have any at the time.

I like that it attaches to the center of the OC, hopefully it won't wag, or break the flange. Others have used this brace geometry with hundreds of hours, so there are high hopes, but no guarantees. An experiment for phase II.

 

[sibriggs]

Single Hole base of #4

How do you handle the single 1/4" hole at the base of the #4 cylinder. There is a hole through the engine case and a corresponding hole in the baffle at that point. But the problem I have is the 2 or 3 inch gap between the case and the baffle. Do you make a long tube busing to butt up to the baffle with a bolt to the case?

Steve

 

[John Tierney]

Spacer

My baffle instructions/plans show a CB-706B spacer in that point; OP 40 plans page 7. Use and AN4-15. I did have to do some creative bending on a little tab that fits behind the big fins on the cylinder, and there is a fair amount of missing paint in that area. Also caught the hole in the baffle on the engine mount bolt cotter pin a couple times.