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Re: Aerobatics in general

Subject: Re: Aerobatics in general
From: Peter van Schoonhoven <pvans@pacifier.com>
Date: Fri, 17 May 2002 07:50:59
 <3CE39E4C.9DCE10BC@cfl.rr.com>
 <180a01c1fccf$de291a30$c92601a3@mark>
 <3CE43195.4B8844BB@cfl.rr.com>
 <19b501c1fd7b$eb5697d0$c92601a3@mark>
 <3CE4F332.FF3EF64D@cfl.rr.com>

On a fully inverted airplane system, the fuel is drawn from a tank with a 
flop tube in it, really just a piece of hose inside the tank with a 
weighted end that flops to whatever is the lowest point in the tank no 
matter which way the aircraft is oriented.

For fuel metering, a fuel injection system does not care which way it is 
positioned, neither does an Ellison Throttle body carburetor, or the old 
PS-5C pressure carburetor. Neither of these have a float chamber.

The oil system also needs a device to assure the pump is not unported. Most 
lycomings use the Christen system, which is a ball check valve system 
mounted to the firewall at the height of the oil pump and connected to the 
pump intake. Then there is a suction line going to the bottom of the oil 
sump, and a second suction line going to the top of the case so when the 
engine is upside down it provides the oil to the pump. The check valve 
prevents sucking air from the opposite suction line.

I have always wondered though, in inverted flight, how much oil is covering 
the back side of the pistons and being sloshed back and forth rapidly, must 
be like a washing machine in there!

Hope this helps explain the concept.

Peter



> > Mark;
> >
> > This thread has been about NEGATIVE "G's". If you keep Positive "G's" then
> > your statement is correct.
> >
> > Jim Brown
>
>
>Whoops, sorry.  Must have missed the bit about negative G.
>
>Can anyone tell me how the oil system keeps oil pumping and how the fuel is
>sucked out of the tank at any angle in a fully aerobatic plane.  Fuel
>injection will remove all the probelms associated with carbs, but I've never
>understood how the oil and first part of the fuel system work.
>
>Cheers,
>Mark.
>
>
> > > > Mark:
> > > >
> > > > The fuel flows from the bottom of the carb bowl into the main fuel
>jet.
> > > Turn
> > > > the carb upside down and the main jet is unported, which is why
>silence
> > > comes
> > > > very rapidly.
> > > >
> > > > Jim Brown
> > >
> > > Doesn't this depend on the type of G you're pulling?  i.e. you can swing
>a
> > > bucket of water upside down and the water will stay at the bottom of the
> > > bucket.
> > >
> > > Cheers,
> > > Mark.
> > >
> > > ________________________________
> > > Mark Jackson - +44 (0)7050 645590
> > > europa-builder@ntlworld.com
> > > http://harley.pcl.ox.ac.uk/~mark/Europa
> > >
> >
> >
>



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