New Varieze - Here's my baffles for a perfectly cooled engine

[borrisl]

I completed this Varieze awhile ago but stumbled on some pictures that some might be interested in. 

The baffling is what works much better than expected. In fact, with the coated exhaust, I now have issues with the heads sometimes not running warm enough. With some careful angling of exit direction and keeping the air attached on exit seems to keep all cylinders within very very close temp proximity.

 

 

 

 

[Kent Ashton]

Nice work.

[borrisl]

Thanks. For hand work it is ok. Would like to cast them in prepeg carbon fiber. Shed some weight. 

[VEZ75]

Im pretty sure Beryl Sanders did these with Chis Woodard and Freeflight Composites. May have templates. They work pretty OK. 

[Jon Matcho]

Thanks. For hand work it is ok. Would like to cast them in prepeg carbon fiber. Shed some weight. 

 

I think they look great!  Fraying carbon fiber and epoxy on the cylinder fins raises some concerns for me.  I suspect they need to be changed much more often. 

[Hummel]

Hallo Richard

I am working on a Vari Eze I just purchased. I will have a new EDM engine monitor and want to improve the cooling. It has now a lot of improvements, even including an additional opening in the top cowl above the nr1 cylinder (although I am not sure if that helps or make it worse because of the additional air pressure on the jot side of the cylinders). 

Can you provide me with some instructions/plans for the bends of ypur aluminim bafflings?

thanks

fabian

[Kent Ashton]

I hope Richard will reply.  Your baffling looks decent but it's hard to tell from pictures.  The main thing is to seal every crack and hole where air can bleed out without going through the fins.  It looks like you are using fairly thick stiff silicone material around the edges which may not conform to the cowls without some extra tinkering.  Stick a light in the engine compartment and look closely with the cowls in place and make sure there are no gaps.  Air pressure in the lower cowl will push the baffles in place slightly but you can't depend on that.  Gotta have a good seal to the cowls.

Are the baffles over your cylinders fiberglass or black silicone?  You could wet out BID with RTV and cut it to shape.  Even hardware-store RTV will stick very well to cylinders and it's a lot easier than bending aluminum and trying to get a good fit-up.  Here's a pic of some BID wraps on an O-360 and you can see how I sealed the edges of the aluminum with silver RTV.   Clean off the cylinders first with some lacquer thinner and the wraps will stick very well.  They can be trimmed smaller with a razor-knife.

[Hummel]

Hi Kent. 

Thanks a lot for your quick reply. Your baffling looks very nice! I think I will try the same. But I wonder around the curves in the baffling. It seems that Richard not only cut the baffling to the right length but added this funny twists  Maybe it helps. 

And you are right, my baffling is very heavy stuff from Aircraft Spruce. I chose the „military standard“ to go on the safe side, but as my wife will also fly the Eze it might turn out that we have a c.g. problem with the heavy engine. The old one was a bit lighter. I am not entirely sure what material the covers are made off. It could be that it is a similar concept as you propose. Fiber with some kind of heat protection... ? I don‘t know. But for sure I will fill all the corners with RTV as you propose!

merry christmas

fabian

The old baffling:

 

[Kent Ashton]

2 hours ago, Hummel said:

It seems that Richard not only cut the baffling to the right length but added this funny twists  Maybe it helps. 

The curls (twists) give you a way to pull the aluminum tight using safety wire and something like nails inside the curls.

You seem to have large holes between the cylinders below your covers and the fit looks a little loose.   You might check that. Yep, the old baffles look a little tired.  

[Hummel]

Hi Kent

Ok, I thought the curls might help the airflow, not only for pulling them together

and yes, you are right, I have quite a few gaps. I will check it when I have it assembled (now I loosened everything a little to work on it) and then definitely close these gaps!

by the way I ordered a lighter baffling material after I gave some thoughts about your comment on how heavy it looks. Better do it right, as long as the Eze is in my shop. 

Cheers 

Fabian

[borrisl]

Most of the baffles were done with posterboard and scissors as a prototype layup. Then the aluminum was cut to those patterns.

I am, however, in the process of converting the Varieze to downdraft cooling and remaking the cowlings. I need to shed some weight on the backend. For this, I'm creating the upper and lower cowlings from carbon fiber and some nice contoured NACA scoops to feed into it.