Anyone tried covering up the new Van's cowl louvers?

[jcarne]

I'm running in the low 300s on CHTs and it's only 29 degrees outside. Probably going to have to restrict some exit area.

I suppose it would be an easy experiment for me to just do but has anyone tried covering up the Van's cowl louvers? How much if any change was noted? I have been toying around the idea of putting electric cowl flaps in their place but don't know if its worth the expense/gain.

Thanks!

[wirejock]

Originally Posted by jcarne

I'm running in the low 300s on CHTs and it's only 29 degrees outside. Probably going to have to restrict some exit area.

I suppose it would be an easy experiment for me to just do but has anyone tried covering up the Van's cowl louvers? How much if any change was noted? I have been toying around the idea of putting electric cowl flaps in their place but don't know if its worth the expense/gain.

Thanks!

Jereme
What did you end up doing?
I'm considering the Antisplat electric louvers but don't want to add the weight.
Also dont want a mechanical control.
If they aren't needed, maybe best not installed.

[Kyle Boatright]

Larry, I would opine that the standard cooling exit provides adequate cooling unless you're going with a hot-rod setup. If you want to optimize things, there are plenty of things you can do (see Dan Horton's cooling threads), but if you're just looking for reasonable cooling performance, the stock setup should be fine.

Louvers are a draggy way to add exit area and cooling airflow.

[PaulvS]

I believe that Vans made the louvers a standard part of the -A kit when the new style nose gear and engine mount was introduced, presumably to counter the additional obstruction in the exit area.

I would consider an adjustable blanking plate simply installed with screws over the louvers. It may be necessary to adjust it a couple of times per year, according to the seasons, or even only for initial setup.

[Kyle Boatright]

Originally Posted by PaulvS

I believe that Vans made the louvers a standard part of the -A kit when the new style nose gear and engine mount was introduced, presumably to counter the additional obstruction in the exit area.

Good info. I haven't seen an example of the updated nosegear kit.

[wirejock]

Originally Posted by Kyle Boatright

Good info. I haven't seen an example of the updated nosegear kit.

Yep. That's why I was curious what Jereme did. He has a virtually identical A model as mine including the engine.

[Finley Atherton]

Originally Posted by Kyle Boatright

Louvers are a draggy way to add exit area and cooling airflow.

Did not do any accurate testing but installed one louver on an already flying 9A and speed seems the same??
Fin 9A

[Kyle Boatright]

Originally Posted by Finley Atherton

Did not do any accurate testing but installed one louver on an already flying 9A and speed seems the same??
Fin 9A

The difference won't be big given the overall small size of Van's louvers (the difference might not be measurable without a lot of effort), but ejecting air at low velocity into the freestream is draggy. Beyond that, a bunch of little slots are less efficient than one larger opening. Drag reduction adds up - a little here and a little there, and eventually the difference will be apparent.

I look at louvers as an expedient way to add cooling to an existing cowl or cowl design where you don't want to re-tool.

[PilotjohnS]

I think the louvers on the new nose geared RV7A/9A might be less dragging than having the exit air flow thru the center area of the old style nose gear with all the stuff hanging there, not to mention the poor corner radius at the transition from the firewall to the bottom skin.

[Mconner7]

I replaced the louver in one side of my -10 with a cowl flap from anti-splat. I was surprised that it does not seem to make any difference in cooling and only costs about 2 knots in cruise speed when open.