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Yes, Ernest, the 104 dB measurement was with only two discs per tube.
Why not put the remaining discs back in instead of just the two? Good
question.
First, there were 8 discs that I had configured, the other two were just
discs with a large 1 3/4" dia hole in them - probably not doing much of
anything, so I dropped them. Two of the 8 discs were damaged leaving 6
discs. To try and prevent the rotation, I picked a discs for each end that
would rotate opposite of the disc at the other end (hopefully more or less
preventing or reducing the rotation), if I had put a third disc on the shaft
it would make it two in one direction and only one in the opposite
direction.
The reason I have not considered putting them back is one:
1. I liked the 6000 static and 6800 max rpm with the two discs (not certain
I could get that with 4 discs per tube - but that is just a WAG - the
additional discs might not much adverse affect on rpm).
2. I want to lower the weight of the assembly and 8 1/8" 3" dia discs adds
twice the weight of 4 discs
3. I don't have a welder to weld the discs to the shaft (thanks Tracy) and
not inclined to pay the price to have a welder do it.
4. The sound, while not quite, appears to be less objectionable (Tracy
stated that the previous exhaust I had hurt his ears at WOT)
5. I want to try the "H" tube cross over to see if it does for my exhaust
what it is reported to do for the automobile.
6. I may get to the point to try additional discs, but have played with it
for close to two months and want to FLY!
So as you see, mainly just rationalization rather than a good reason {:>)
Ed
----- Original Message -----
From: "Ernest Christley" <echristl@cisco.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, January 18, 2005 5:17 PM
Subject: [FlyRotary] Re: turbine Exhaust??????? - No! not turbo related
On Tue, 2005-01-18 at 15:32, Ed Anderson wrote:
>
> With Tracy's kind help, I stripped all but two discs from each rod
> (making certain that we paired discs which would want to rotate in
> opposite direction (hopefully stopping any - or most rotation). Then
> Tracy welded the discs, nuts and rod together. I inserted that
> arrangement back into the 3" tubes, closed them up and flew the rest
> of the flight with that arrangement.
>
> The trip to Lakeland and home would seem to indicate I have found a
> satisfactory (for now) solution. I hit 6000 rpm static on take off
> this morning and got up to 6600 rpm straight and level (which is 200
> rpm more than I got with the straight (empty) 2" tubes. I intend to
> make one more modification by placing a cross feed tube between the
> entrance to the two mufflers, the old "H" pipe hook up which according
> to many sources, assists in lowering noise and improving power.
Ed,
1) was the 104dB with only the two disk?
2) why did you drop to only two when you found the cause of the
problem? Why are you not considering putting them back?
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