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From: Bulent Aliev <atlasyts@bellsouth.net>
Subject: Re: [FlyRotary] Re: First flight - oil temp
Date: Mon, 7 Aug 2006 20:18:35 -0400
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Al, I would suggest you work on one side at the time. Inlet or =20
outlet, so you can see which way it changes. If you correct both =20
sides at the same time, there is no way to know which correction was =20
beneficial.
Sorry to hear about the fuel leaks,but looks like many people had =20
this problem. I had to re-do my sight gauges only for now.
Keep us posted.
Buly
On Aug 7, 2006, at 6:25 PM, Al Gietzen wrote:

> I think your conclusion about the missing ram air at the intake is =20
> the major reason why the oil cooling did not improve at higher air =20
> speed. A second point may be the air outlet. It looks like a =20
> turbulence could form where the back scoop protrudes from the wing =20
> surface. This turbulence could produce vorticies over the edge at =20
> the outlet, reducing the effective area of the outlet. A more =20
> continous transition from the wing surface to the scoop surface =20
> would reduce the possibility of this to happen.
>
>
> Thanks, Richard and all for comments and suggestions.  Originally I =20=

> had a more simple up-sloping fairing (I guess that=92s what you mean =20=

> by =93more continuous transition=94?).  After some study and =
consulting =20
> with an aeronautical engineer, the conclusion was that it would =20
> cause too much turbulence behind.  The current airfoil shape was =20
> the recommended approach in order to keep the flow attached, have =20
> minimum turbulence behind, and least amount of drag. So what=92s =
right?
>
>
> I think those suggesting more of a ram inlet scoop, and those =20
> suggesting a less shrouded exit fairing are both correct.  The net =20
> change needed is more pressure differential between inlet and =20
> outlet, and either change will likely accomplish that, and either =20
> change will result in more drag.
>
>
> As I see it now; the inlet was designed on the basis of a more =20
> negative pressure at the outlet, alleviating the need for a ram =20
> scoop.  The outlet was designed based on an assumption of an inlet =20
> air flow equivalent to a ram scoop, so the end result was a =20
> combination that is not effective.  The exit fairing is designed to =20=

> speed up the exit flow so it will merge at something closer to free =20=

> stream velocity (reduce drag), and simply to protect the core from =20
> things being dropped in.  With too little inlet pressure to produce =20=

> the flow there will likely be very turbulent flow aft of the =20
> fairing, increasing the pressure in that area.  More flow should =20
> help alleviate that issue =96 agree? Cutting back the fairing (moving =20=

> forward as in the Rutan case) increases the negative pressure but =20
> brings the air out at much less than free stream velocity (more drag).
>
>
> So, which is better for cooling and drag - scoop or unshrouded exit?
>
> An extended scoop is an easier thing to try.  Of course, I may =20
> still be missing the target entirely.
>
>
> Also, regarding boundary layer and scoop, keep in mind that this =20
> inlet is in the wing aft of the strake, so there is only about an =20
> average 4-5=92 of buildup, and then only in the case of gear up.  For =20=

> a very wide narrow scoop as this, there is no effective way of =20
> diverting the B.L.; so the best bet is to mix it (VGs), and ingest it.
>
>
> Meanwhile, I have another problem to deal with - a fuel leak(s) =20
> through the inner skin of the foam core strake into the foam.  Bummer!
>
>
> Al
>
>
>