New optional plans OP-58 - Lower cowl louvers for RV-6/7/9

[greghughespdx]

Van's has published OP-58, an optional (OP) plan set which describes the installation of lower-cowl louvers in the RV-6/6A. RV-7/7A and RV-9/9A engine cowls (note: this kit does not fit other model cowls). The louvers may be used where additional exit air flow, such as for cooling purposes, is desired.

You can order kit "COWL LOUVER KIT" from the Van's Aircraft online store or by calling the Van's order desk. Cost for the kit is $8.00 plus shipping and it includes parts for creating louvers on both sides of the lower cowl. Complete instructions describing cowl modifications and installation of the aluminum parts included in this kit are found in the OP-58 document. The builder/installer will need to modify the lower cowl and will supply fiberglass fabric and other materials used during installation.

You may download the OP-58 plans/assembly instructions at this link.

greg

[Arie]

I think this is a great option. Any idea how much CHT will drop?
Interesting that the louvers bend inwards ( inside of the cowl) iso outwards. What would be the reason for that?

[scard]

Wow. There is a welcome underlying shift in messaging with this addition.

[airguy]

Originally Posted by scard

Wow. There is a welcome underlying shift in messaging with this addition.

Agreed. Instead of "you're doing it wrong" now we are getting "here is how to do it better, since you're going to do it anyway."

[bcondrey]

This is essentially how it?s done with the stock RV-10 cowl.

[engineerorange]

Now somebody hurry up and do a good job testing this new "option" for effectiveness in lowering CHTs and speed penalty after installation.

[rvbuilder2002]

Since in all instances where the owner was asking for help in improving cooling, I have never inspected an RV that didn't have at least some level of issue with the baffling / cowling installation, and most of the time it was more than just minor leakage (Even though they were sure that it was as good as it could be), so this shouldn't be considered a Van's endorsed method of resolving cooling issues.
This is for instances where the rest of the cowl/plenum system has been optimized but other factors make adding additional cooling flow path area, beneficial.

[vfrazier]

Originally Posted by Arie

I think this is a great option. Any idea how much CHT will drop?

about 30 degrees CHT difference on N540VF, IO-540 F1 Rocket on hot days.

It's easy to install an inside track(s) to hold an aluminum sheet to block these off in the Winter.

[DanH]

Originally Posted by rvbuilder2002

Since in all instances where the owner was asking for help in improving cooling, I have never inspected an RV that didn't have at least some level of issue with the baffling / cowling installation, and most of the time it was more than just minor leakage

Same here.

Scott, curiosity questions please. Assuming our intrepid owner is forced to fly with crappy baffling and too much timing advance...

(1) Why not just remove the core, make the 4 ply 9-oz layup, and cut the slots, skipping the metal louver?

(2) Or, why not enlarge the standard exit? A simple 45 degree cut increases exit area by 41%. Costs nothing and can be done in 15 minutes.

[toc pilot]

I installed louvers during my build. I found them to be very effective in keeping the CHTs and oil temperatures in check during the summer months here in Arizona.

https://www.facebook.com/18143611188...type=3&theater