Mailing List flyrotary@lancaironline.net Message #66669
From: Steven W. Boese SBoese@uwyo.edu <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: [FlyRotary]: RD-1C input shaft oil seal ... Drain Hole question for Steve B.
Date: Sat, 6 Mar 2021 02:02:41 +0000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Finn,

When operating with both the vent and the larger drain, my gearboxes do not fill completely with oil.  They contain about 6 oz of oil during operation compared to about 20 oz when full.

Steve Boese

> On Mar 5, 2021, at 12:28 PM, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:
>
> So you're saying that the bigger drain hole and addition of vent will not prevent the drive to fill up with oil?  :(
>
> Finn
>
>> On 3/5/2021 12:22 PM, Sboese sboese@uwyo.edu wrote:
>> Jeff,
>>
>> The supply lines to my redrives are AN4.  The oil flow rate is restricted internally by the construction of the redrive.  Without a vent, the air initially inside the unit is entrained in the oil primarily by the action of the gears, the air is eliminated through the drain, and the unit is quickly completely filled with oil. This happens regardless of the size of the drain At this point, the oil out flow rate must equal the oil in flow rate.  The size of the drain limits the internal pressure of the unit.  The larger size drain allows the oil to be removed by gravity alone and prevents the oil from coming out of the added vent.  With the vent connected to the engine crankcase above the oil level, the pressure inside the redrive is now the same as the pressure inside the crankcase.
>>
>> Steve Boese
>>
>>> On Mar 5, 2021, at 5:51 AM, Jeff Whaley jwhaley@datacast.com <flyrotary@lancaironline.net> wrote:
>>>
>>> ◆ This message was sent from a non-UWYO address. Please exercise caution when clicking links or opening attachments from external sources.
>>>
>>>
>>> Hi Steve B., with respect to your response about drain hole diameter ...
>>> What is the size of your oil inlet hose?
>>> Did you experiment with oil inlet size - if oil won't all come OUT perhaps we are putting too much IN?
>>> Just a thought.
>>> Jeff
>>>
>>> Finn,
>>>
>>> When I installed a vent in the top of my RD-1C drive it acted as an additional drain.  The drive operated completely filled with oil until the size of the original rear drain was increased to an ID of ~5/8" (1/2" NPT pipe).
>>>
>>> Steve Boese
>>>
>>>
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