What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

VR temp reduction

S

Sink

Well Known Member
I know there is a service instruction that allows you to move the VR inside the cockpit, but if you haven't done that here is a way to help your VR temps.

I have seen RV12's that have the reg/rec. (voltage Reg) air hose up into the fresh air intake for the plenum. It barely protrudes into the side of the air intake tube. This design seems like it would cause a vacuum as the fast air moves past this small reg/rec tube. This would cause less air circulation delivered to the VR. I pushed the VR tube through the side of the fresh air tube farther and siliconed it facing forward into the positive pressure air stream. Dropped the temps by 20F on the reg/rec. The other heat sources is the air from the back of the cooler and the radiated heat from the #4 exhaust. Next I'll wrap that #4 pipe with some header wrap. This should stop convected heat and radiated heat on the VR. I would bet that this will bring the temps down under 140F or more. 170F is a VR and ignition module killer.
 
Last edited:
Cool is good

I installed my VR inside under the avionics shelf after reading all the horror stories while building my (still-in-the-basement) -12.

Still, since "coolest is best-est" I'm been thinking about using some ductwork and an inlet or outlet somewhere to push or pull outside air through a shroud around the VR. It would be a later mod, of course.

Might also reduce the likelihood of "grill marks" on someones knee? <grin>

Other ideas and/or cautions?
 
DaveWelch said:
I installed my VR inside under the avionics shelf after reading all the horror stories while building my (still-in-the-basement) -12.

Still, since "coolest is best-est" I'm been thinking about using some ductwork and an inlet or outlet somewhere to push or pull outside air through a shroud around the VR. It would be a later mod, of course.

Might also reduce the likelihood of "grill marks" on someones knee? <grin>

Other ideas and/or cautions?
Click to expand...

When a cooling tube is connected to the engine cooling plenum on an aircraft, it is not working on the physics of dynamic pressure, it is static pressure. This is a pretty basic principle used on most all light aircraft. When there is a pressure differential between the two ends, there is flow. In the case of the RV-12 regulator location, the amount of flow is not enough to overcome the radiant heat from the nearby exhaust, and the hot outlet flow from the radiator.
All other modifications ideas aside.....
The new location in the cockpit was selected for a specific reason... so that if it was ever necessary for operation in super hot climates, a small shroud could be added that partially overlapped the cooling fan. The flow produced by the fan would move some air over the regulator fins.

As for grill marks on the knees? If you sit in the airplane and look at where your knees are, I think you will find that if someone ever gets there knees in contact with the regulator, their will likely be marks elsewhere on their body that will be of much greater concern.
 
Thanks Scott, I see what you mean about the knees. It would take an "unusually configured" person to achieve interference there.

My Granddaughters hands and feet might have been a better example? They seem able to get into about anything anywhere. Of course they will be buckled in and double checked by Grandpa during operations!

I really like the partially shrouded fan and VR idea.

Thanks!
 
If the VR is mounted on the bottom of the avionics shelf it seems that convective cooling is not possible since the hot air can't rise.
 
There are many VR installations inside the engine compartment. They just aren't located right behind the cooler delivering hot air and right behind the #4 exhaust pipe. Mounted in the proper location heat within the cowl shouldn't affect them otherwise most Rotax aircraft VR's would be failing constantly. Remember VR's produce their own heat and it needs to dissipate its own heat.
Too much of a load or too little can increase its internal heat.
 
You must log in or register to reply here.
Back
Top