REFLECTOR: Fwd: My Velocity setup
Jim Agnew
jim_agnew_2 at yahoo.com
Sat Dec 4 08:18:49 CST 2004
If you look at a lot of the new small blimps you will find a fan inside the
engine cowling attached between the engine prop hub and the prop extension.
The fan is a flat many blade device that looks like the turbo fan on the front
of many of the large jet engines. Obviously blimps don't have a lot of ram
pressure and spend a lot of time almost stopped. This installation was on
Lycoming engines.
Jim
--- Jim Sower <canarder at frontiernet.net> wrote:
> Probably. I've seen such a setup on a Long-EZ and the guy swears by it.
>
>
> ouglas Holub wrote:
>
> > Would it help to suck air through the NACA ducts if I put a fan on the
> > prop extender just before it exits the cowl?
> > Doug Holub
> >
> > ----- Original Message -----
> > *From:* Al Gietzen <mailto:ALVentures at cox.net>
> > *To:* 'Velocity Aircraft Owners and Builders list'
> > <mailto:reflector at tvbf.org>
> > *Sent:* Friday, December 03, 2004 10:54 AM
> > *Subject:* RE: REFLECTOR: Fwd: My Velocity setup
> >
> > My idea behind this is to scavange some of the flow that comes
> > through the bottom radiator, across the bottom of the pan, and out
> > the "suction slot". at about 18" from the center of prop rotation,
> > it should also add to the suction the prop places on the cowl
> > opennings. Well.. at least that is my idea, we'll see if it works
> > out. I am hoping that I can get away without an oil cooler with
> > that setup. No worries though, I have a backup to put an inline
> > cooler on the #2 NACA scoop if I need it.
> >
> > Keep in mind that the reduced pressure (suction) generated by
> > the prop dissipates rapidly (exponentially) as you move away from
> > the prop, so even a foot is a long way - and at cruise it is
> > almost non-existent; you have to rely on dynamic pressure and
> > whatever gradients are produced by the flow. Remember, the air is
> > standing still, the airplane is moving. Some air is getting
> > pushed/pulled downward by the airfoils, some is being pushed back
> > by the prop, the rest is getting out of the way as best it can.
> >
> > Al
> >
> >
> ------------------------------------------------------------------------
> > __
> >
>
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=====
James F. Agnew
Jim_Agnew_2 at Yahoo.Com
Tampa, FL
Velocity 173 Elite Aircraft Completed & Flying
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