engine baffleing
 

3w 157 i know it ulgy i only care if it cools the engine besides that it hidden under the cowl please tell me if u all think this will work thx

RE: engine baffleing
 

for some reason i cant get these pics to show up right the cylinder is coverd on top as well

RE: engine baffleing
 

Pix are not really viewable but it looks like you have the spark plug excluded from cooling. It needs to see cooling air also.

RE: engine baffleing
 

does not look like you have nearly enough volume around the engine.

RE: engine baffleing
 

good point i thought it was good to keep it tight so air is forced to only go threw the fins , only letting it to exit at bottom back of engine . should i make it all bigger? thx u guy i must get this right

RE: engine baffleing
 

RE: engine baffleing
 

RE: engine baffleing
 

Rule of thumb is 3x air exit area to inlet air area.  Baffle should channel air; not really enclose the head.

RE: engine baffleing
 

better pics</p>

RE: engine baffleing
 

Could be a lot better. You have an inlet that provideds for a lot of inlet area but fails to direct any of it to the hottest portions of the cylinder. What makes that even worse is a lack of exit area. You're arrangement may be making things worse because it is trapping most all the cooling air at the cylinders, permitting it to collect heat without releasing any. You have to provide a place, with appropriate volume, to escape, taking heat with it. You're method of slowing the intake air is good, but without a means to exit it is likely getting pretty hot. Likely hotter than it would without any baffling at all.

RE: engine baffleing
 

ok make good sence thx for your in put ive tore it down and redid it . im working on the pics to show you all . i gave it 3in behind the cylinders for exit

RE: engine baffleing
 

The usual ratio for hot air exit for cool air inlet was previously noted at 3-1, meaning triple the exit area for hot air compared to what is provided for cool inlet air. That ratio is adjustable between 2 and 4 to 1, but that adjustment is conditional. The lower ratio can only be used if you have done something to accellerate the exit air flow, such as the construction of a ramp at the beginning of the exit area outside the cowl.

For an example of how air moves, go out to the garden and lay a water hose on the ground. Turn on the water and watch the way the water moves over and around obstructions. Place a few small rocks and other items in the way of the flow and observe how the water adjusts to flow as freely as possible around and over the obstructions. The water always prefers to go around an obstruction, and that water can be directed to flow where you desire it to with the additition of dams and barriers for deflection. Plan your cooling air system with those observations in mind. You will have used a short course in fluid dynamics to have built your cooling air system. A rather good one since it was based on visualizations and practical experience.

RE: engine baffleing
 

ok im hoping this is good im thinking the top half of cowling will be close enough to the heads air goes threw and out my new exit holes

RE: engine baffleing
 

this is looking better in the last picture.

The trick with cooling air is that it needs to hang around a little in order to achieve heat transfer. Air is not a good geat transfer medium.

The tricks I use is a large air inlet that is followed by a larger volume behind the inlet. This slows the air down.
If you can then channel the air through a exit that is smaller than the volume inwhich the block and head sits but diverging to the fuselage exit you will achieve good air extraction.

The general rule of air inlet must be 1/3rd the size of the exit is not a good one IMO. Look at race cars. Thy use a certain size inlet, sculted air flow pathways under the body to exit at a vent that is usually of equal area or less than the inlet.

I understand this may be controversial

RE: engine baffleing
 

It is looking a lot better.

The 90 degree angles wil assist that slowing of air speed. I also agree with TimBle in a 1-3 ratio not being ideal for air cooled systems. Unfortunately the design of a small inlet, small outlet systems requires more design capability than the average modeler has available. I use a small in, small out cooling systems but a lot of design math and composite design went into them. As with anything else there is a down side. When the plane stops moving the inlet/outlet air stops with it, requiring a secondary means of generating airflow. Not something the average modeler would want to tackle.

For most modeling puoposes the 1-3 ratio, combined with a little planning, works good enough.

RE: engine baffleing
 

1:1 intake to exit area can be enough, I would like to see more of your exit area before commenting, too many people concern themselves over what goes in. Exit is far more important - create the right low pressure by installing louvres and the air will move through and cool the engine.once you have airflow then directing it in the right places works even better, but trying to direct it when there is no pressure difference is also not going to do anything. Louvres creating low pressures work extremely well around the cowl as these are in the best airflow (propwash) when the plane is stationary or in 3D, they will continue to draw the airthrough the cowl....