Aircraft engine oil flow mass?

Discussion in 'Firewall Forward / Props / Fuel system' started by 4trade, Apr 10, 2012.

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  1. Apr 10, 2012 #1

    4trade

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    Does anybody know how much oil flow through system/ minute for typical 4 cylinder aircraft engine?

    I need to do some modification for O-200 engine block, because i use it for aerobatics/ inverted flight. I need to drill drain hole for oil that flow at front of case/ back of case in inverted position. If i know approximate flow rate, i can make it smallest possible one without weaken my case too much.
     
  2. Apr 10, 2012 #2

    Hot Wings

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    I found this tucked in among some other info. Kind of generic but should give you a starting point.








    Q: What do you think of these "super magnets" that attach to the outside of the oil filter?
    A: First of all you have to realize, that there is very little ferrous metal in an aircraft engine. However if you wanted to collect what little there is, it really is not very effective trying to accomplish it at the oil filter location The oil is typically traveling at over 7-12 gal/min as it goes through the oil filter. These Neodymium "super magnets" as they are commonly called, are really not so super or strong enough to pull this ferrous metal out of suspension as it whizzes by at this velocity. It just isn't possible. In addition, most people don't realize that Neodymium magnets loose their magnetic properties the higher the temperature gets, where at 200°F they have but 10% of the magnetic forces left. Since your engine typically operates at 185°F, you can see the inefficiency of using a super magnet for this application. If you really wanted to put a magnet into your system, the ideal place would be the bottom of your drain plug. This way what little metal you may have suspended in your oil, is allowed to slowly fall out of suspension to the bottom of your oil pan, where it slowly migrates over to the lowest point in your sump, where it could be collected by a simple magnet, just like automobile engines have done for years.
     
  3. Apr 10, 2012 #3

    TFF

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    I would think 2 Qts a minute would be about right. Somewhere in a maintenance manual will have oil level at which damage occurs; above that number. Are you going dry sump? If not you will have a limit of inverted even with inverted scavenging.
     
  4. Apr 10, 2012 #4

    4trade

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    I was planning to use Christen oil valve and some heavy modification to oil pick up tube. I will build pick up for inverted position too. I am building Cassutt and i will use it for aerobatics....so i need to modify that engine for it. Cassutt plans show "oil trap door" and modified oil pick up tube for short term inverted operation, but i need better solution for it....so heavy mod´s will be only way for my purpose.
     
  5. Apr 11, 2012 #5

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    The aerobat crankcase vent is a good mod to do.
     
  6. Apr 11, 2012 #6

    4trade

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    Right, i must use that one for sure.
     
  7. Apr 12, 2012 #7

    Joe Fisher

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    I have thought about using the flapper in the oil tank and some kind of a swivel oil pick up. Then costume build an oil pump to run off of the vacuum pump drive suck oil out of the top of the crank case and pump it to the oil tank.
     
  8. Apr 12, 2012 #8

    Hot Wings

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    Then costume build an oil pump to run off of the vacuum pump drive suck oil out of the top of the crank case and pump it to the oil tank.

    Could there be a way to modify the vent so that in the inverted position the oil system functions similar to the Rotax.
     
  9. Apr 12, 2012 #9

    4trade

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    Cassutt plans have flap that close oil drain back when inverted, they call it "oli trap door" and oil pick up tube have additional slider tube around of original pick up tube.....that slider allow oil pick up for inverted position. Simply but great system for short time inverted.
     
  10. Apr 12, 2012 #10

    Joe Fisher

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    The Rotax works because the oil tank is the only crank case vent. The piston ring blow by forces the oil to the oil tank.
    For the Continental the oil out let would work best if it is at the top rear of the case since in inverted flight with power the airplane would be nose up or accelerating.
    In the mid 60's my friend was converting a C90 for a Smith Mineplane. He called his flapper valve a Leper con toilet seat.
     
  11. Apr 12, 2012 #11

    Joe Fisher

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    Another idea in the Bellanca Citabria parts book there is an electric oil pump part #8110-C. I don't have the maintenance manual but I remember there was an optional system that would suck oil out of the top of the engine and pump it into the relief valve. The pump motor is controlled by a mercury switch.
     
  12. Apr 12, 2012 #12

    4trade

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    I was thinking something like of that too, but i think that Christen valve is lighter and it is certainly proof, simple, mechanical device.
     
  13. Apr 12, 2012 #13

    bmcj

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    Did we ever get an answer about the flow rate? I saw two posts... one said 2 quarts per minute and the other said 7-12 gallons a minute. That's quite a bit of difference between the two.
     
  14. Apr 12, 2012 #14

    Hot Wings

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    If you have a pump in hand it would be pretty easy to seal up one tooth and use a pipette to measure the volume. A quick cad sketch of a pump with a 1.5" diameter and a 3/4" thickness gave a tooth volume of .0553 in^3. Multiply by 2 (number of teeth doing work) by the number of teeth in pump gear (8 for this) multiply by rpm. (2700)

    =10.33 gallons.
     
  15. Apr 12, 2012 #15

    Joe Fisher

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    Oil pump turns half crank shaft speed.
     
  16. Apr 12, 2012 #16

    Joe Fisher

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    Weight is a big issue in an airplane that small. An electrical system will noticeably reduce performance.
     
  17. Apr 12, 2012 #17

    Hot Wings

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    Oil pump turns half crank shaft speed.

    Then device by 2! My mistake. :emb:
     
  18. Apr 12, 2012 #18

    4trade

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    I believe there is lot of cavitation because oil pump is working against pressure "wall", so that flow rate is probably way less than 5 gallon/ minute. Volume of pump don´t tell truth when pump is building pressure.

    I was disassemble my case today, and find out that there is approx (eyeballing) one sq/inch opening at bottom of case for oil drain. I will cut out same amount for top of case too, just to be sure.
     
  19. Apr 12, 2012 #19

    Hot Wings

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    I believe there is lot of cavitation because oil pump is working against pressure "wall", so that flow rate is probably way less than 5 gallon/ minute. Volume of pump don´t tell truth when pump is building pressure.

    There may be a bit of loss as the oil bypasses the gears between the housing but this is a positive displacement hydraulic pump and cavitation shouldn't be a factor unless it's sucking air as well. The flow through the filter may be less because of dump from the oil pressure relief system but this oil quantity needs to be handled by the drain as well so should be included.
     
  20. Apr 12, 2012 #20

    4trade

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    Thank´s for clearing that one...i was wondering that a lot. I am old boat builder, so my limited understanding for cavitation is based on a prop, not for gear pump type solution where pressure can´t escape.
     

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