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I am contemplating locating my oil cooler under my 912 ULS engine, between the two front exhaust pipes.

Viewed from the front; The cooler will fit either horizontally (hose connecting spigots on top) or vertically (hose connecting spigots on the aircraft right side).

Viewed from the side; Both orientations involve the cooler being sloped (lower edge back) to conformed to the cowling shape. The actual slope is yet to be determined. 

The horizontal position, looks nice and conventional but brings the cooler into close proximity with the exhaust pipes - its just okay but as a precaution I will probably fit some heat shielding. 

The vertical position, gives greater clearance to the exhaust pipes (less chance of radiant heat damage) and the hose spigots line up nicely with the in/out oil hose directions.

Added considerations;

The removal/displacement of air from the cooler looks to be better in the vertical position (oil pump spigot very much higher than the incoming oil reservoir spigot) than the horizontals which has both spigots at the same level.

Also the in/out oil hose will be shorter and have less bend radius, in the vertical position, compared with the horizontal.

I can not see any reason for the oil cooler to function better/worse either vertically or horizontally mounted.

I await your comments, on my two options, with great anticipation.

 

  • Re: Oil Cooler Orientation

    by » 2 years ago


    In my experience, tight bends in the hose are your biggest problem as they can restrict flow, particularly as the hose ages and starts to collapse when it gets hot. I would do what you can to avoid them. Having the hoses close to the exhaust doesn't seem to be as big a problem and it is relatively easy to insulate them. It goes without saying that it needs to be mounted in such a way that there is reasonable air flow through the cooler.


  • Re: Oil Cooler Orientation

    by » 2 years ago


    I would position it horizontally and most times there are two 90 degree fittings that come off the top ports. I would also position it with the ports on the top and not the bottom. There are several aircraft companies that position it this way. You want it to have good air flow so it does need to face outward.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: Oil Cooler Orientation

    by » 2 years ago


    Roger Lee wrote:

    I would position it horizontally and most times there are two 90 degree fittings that come off the top ports. I would also position it with the ports on the top and not the bottom. There are several aircraft companies that position it this way. You want it to have good air flow so it does need to face outward.

    Roger thanks for the input.

    You have not given any rational for your suggestion - why horizontal?

    I have all the required fittings - that's not a concern.

    I think you miss understand what I am contemplating - I am considering mounting the cooler vertically ie small sides top/bottom with the cooler attach fittings on the aircrafts right side. The top fitting going to the pump, bottom from oil tank. This actually looks to facilitate shorter straighter hose connections - I believe a good thing. It would also mean any chance of air being trapped in the cooler (initial oil fill) could not happen.

    To better explain my idea;  pick up an oil cooler have it facing you with the fittings on top (cooler horizontal). This is with some small variations the regular way of mounting the cooler. Now rotate it 90 degrees to the left (cooler vertical) fittings now on your left (installed aircraft right when facing aircraft spinner).

    The airflow will still pass from front of cowling through oil cooler and out into the larger space of the cowling - this wont change.

    I do not think the coolers efficiency would be compromised (by being vertical rather than the usual horizontal) - air will still pass over the cooling fins and heat carried away.

     

    I may be wrong in all  this and there may be other factors I have not considered, hence my question


  • Re: Oil Cooler Orientation

    by » 2 years ago


    Kevin Stewart wrote:

    In my experience, tight bends in the hose are your biggest problem as they can restrict flow, particularly as the hose ages and starts to collapse when it gets hot. I would do what you can to avoid them. Having the hoses close to the exhaust doesn't seem to be as big a problem and it is relatively easy to insulate them. It goes without saying that it needs to be mounted in such a way that there is reasonable air flow through the cooler.

    I agree Kevin - what of the other potential benefits I have suggested?

    Oh! & do you foresee any negatives/problems with a vertically mounted oil cooler?


  • Re: Oil Cooler Orientation

    by » 2 years ago


    "You have not given any rational for your suggestion - why horizontal?"

    Because I have to remove fittings and or hoses quite often and vertical would make that difficult, messing and likely an oil purge. Depending on which fitting is up that may trap air in the top of the cooler even with a purge. It has nothing to do with the cooling. I'm not saying it can't work just the horizontal is better.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


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