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From: "Richard Sohn" <unicorn@gdsys.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-890077@logan.com>
Subject: Re: [FlyRotary] Re: Single Rotor Balance
Date: Wed, 20 Apr 2005 14:52:06 -0700
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----- Original Message ----- 
From: <Lehanover@aol.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, April 20, 2005 10:03 AM
Subject: [FlyRotary] Re: Single Rotor Balance


> In a message dated 04/20/2005 11:42 Central Daylight Time,
> fosborn@infowest.com writes:
>
> << I realize this is a bit of a quibble but with the increasing interest 
> in
> single rotor
> engines there should be adequate recognition that balancing one is not 
> easy.
> Balance Diagram courtesy of PL's ACRE NL.
>
> With all due reverence, Lynn.
>
> Fred O. >>
>
>
> Sounds good to me.
>
> Include the entire assembled weight of the rotor less the apex seals and 
> apex
> seal springs.
>
> A balance person might add in that a slight imbalance to account for
> compression and power stroke may make things smoother. I have never built 
> one so I
> advise the assistance of those who have.
>
> Lynn E. Hanover
>
My single rotor is running with analytical balance only. The main reason for 
doing that was to get the test rig running without having to spend time and 
money for machine balancing. As it turned out, it is sufficient for a start.
I see three steps in the balancing quality. The first one is calculated 
balance, considering rotor with seals, and balance weights. The second is, 
rotor with seals, rotor CG offset due to stationary gear, oil in rotor, 
balance weights exact location. I believe the second step is a precondition 
to the third step in order to come close to what the balancing machine can 
handle.
On my engine, the first step gave me acceptable running quality for up to 
4500RPM, which was more than sufficient for the testing scope. I made a new, 
lighter flywheel, which I have run briefly, and the engine is running even 
better than with the first one (pure luck). With the mods going into the 
parts now, like shorter e-shaft and final design side housing, the flywheel 
and counter weight locations are fixed, I am ready for step 2. In this 
effort I am using more sofisticated moment measurement procedures than in 
the first step.
I am expecting to be able to do most of the testing, including 7500RPM 
before goning to a balancing machine.

Richard Sohn
N-2071U


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