Help with in-cowl muffler

Help with in-cowl muffler

Post by Dan & Anne Mile » Mon, 05 May 1997 04:00:00



I am (slowly) building a Great Planes P-51 with an OS 46FX
engine.  I am using a Slimline Pitts-style muffler, so the
engine will be mostly enclosed except for cooling holes.

This is the first cowled plane I have built, so I'm on new
ground here.  The otherwise good Great Planes instructions
aren't telling me what I need to know.

So I'll throw this to the 'Net wizards.  I was planning to use
a Du-Bro #334 Kwik-Fill fuel valve on the side of the fuselage
near the fuel tank.  I assume that will let me refuel without
pulling any fuel lines off the engine or muffler.  But what
happens when the tank is full?  Normally, I am used to seeing
the fuel line to the engine (which is pulled off during fueling),
spit fuel when the tank is full.  How should this work now?

Do I need to run a tank vent line down and out the bottom of
the fuselage?  Is that a third line coming out of the tank?
As you can see, I'm stuck here.  I'd appreciate any help you
can provide.  An e-mail directly to me would be the best way to
respond.

--Thanks, Dan

 
 
 

Help with in-cowl muffler

Post by Brett Jaff » Mon, 05 May 1997 04:00:00


Just keep pumping until the fuel drips out of the muffler.  Actually, if you
listen very closely, you can hear a "whoosh" sound from the muffler just as it
starts to overflow with fuel.  Anyway, I've been using an OS .46 SF and a
Slimline pitts muffler for years and never had a problem with letting it over  
flow (except for spilling a bit of fuel, of course).


Quote:
>I am (slowly) building a Great Planes P-51 with an OS 46FX
>engine.  I am using a Slimline Pitts-style muffler, so the
>engine will be mostly enclosed except for cooling holes.

>This is the first cowled plane I have built, so I'm on new
>ground here.  The otherwise good Great Planes instructions
>aren't telling me what I need to know.

>So I'll throw this to the 'Net wizards.  I was planning to use
>a Du-Bro #334 Kwik-Fill fuel valve on the side of the fuselage
>near the fuel tank.  I assume that will let me refuel without
>pulling any fuel lines off the engine or muffler.  But what
>happens when the tank is full?  Normally, I am used to seeing
>the fuel line to the engine (which is pulled off during fueling),
>spit fuel when the tank is full.  How should this work now?

>Do I need to run a tank vent line down and out the bottom of
>the fuselage?  Is that a third line coming out of the tank?
>As you can see, I'm stuck here.  I'd appreciate any help you
>can provide.  An e-mail directly to me would be the best way to
>respond.

>--Thanks, Dan

__________________________________________________________________________
Brett Jaffee

http://www.earthlink.net/~jaffee



__________________________________________________________________________

 
 
 

Help with in-cowl muffler

Post by Ian Mitchel » Tue, 06 May 1997 04:00:00


--
Ian Mitchell



Quote:
> I am (slowly) building a Great Planes P-51 with an OS 46FX
> engine.  I am using a Slimline Pitts-style muffler, so the
> engine will be mostly enclosed except for cooling holes.

> This is the first cowled plane I have built, so I'm on new
> ground here.  The otherwise good Great Planes instructions
> aren't telling me what I need to know.

> So I'll throw this to the 'Net wizards.  I was planning to use
> a Du-Bro #334 Kwik-Fill fuel valve on the side of the fuselage
> near the fuel tank.  I assume that will let me refuel without
> pulling any fuel lines off the engine or muffler.  But what
> happens when the tank is full?  Normally, I am used to seeing
> the fuel line to the engine (which is pulled off during fueling),
> spit fuel when the tank is full.  How should this work now?

> Do I need to run a tank vent line down and out the bottom of
> the fuselage?  Is that a third line coming out of the tank?
> As you can see, I'm stuck here.  I'd appreciate any help you
> can provide.  An e-mail directly to me would be the best way to
> respond.

> --Thanks, Dan

Dan,

A solution I have used is to bend a piece of brass tubing into a horse-shoe
shape and epoxy it (legs in) to a ply block attached to the firewall near
the muffler cut-out so that the cowl will clear it on removal.  Cut out
about half the curved external protruding section of the horse-shoe and
join the two sections with fuel tube.  Connect one internal leg to the tank
overflow and the other to the muffler pressure ***.

To refuel simply disconnect the fuel tube joining the two external curved
tubes.  The fuel overflow will run out one of them.  Replace the tubing
before flying.

--
Ian Mitchell

 
 
 

Help with in-cowl muffler

Post by Sherwin Arcul » Wed, 07 May 1997 04:00:00


You might get a set of Fuel Dots from RC Models in Tulahoma Tn. Use with 2
T's from Robart.Your problems will go away.

Quote:

>--
>Ian Mitchell



>> I am (slowly) building a Great Planes P-51 with an OS 46FX
>> engine.  I am using a Slimline Pitts-style muffler, so the
>> engine will be mostly enclosed except for cooling holes.

>> This is the first cowled plane I have built, so I'm on new
>> ground here.  The otherwise good Great Planes instructions
>> aren't telling me what I need to know.

>> So I'll throw this to the 'Net wizards.  I was planning to use
>> a Du-Bro #334 Kwik-Fill fuel valve on the side of the fuselage
>> near the fuel tank.  I assume that will let me refuel without
>> pulling any fuel lines off the engine or muffler.  But what
>> happens when the tank is full?  Normally, I am used to seeing
>> the fuel line to the engine (which is pulled off during fueling),
>> spit fuel when the tank is full.  How should this work now?

>> Do I need to run a tank vent line down and out the bottom of
>> the fuselage?  Is that a third line coming out of the tank?
>> As you can see, I'm stuck here.  I'd appreciate any help you
>> can provide.  An e-mail directly to me would be the best way to
>> respond.

>> --Thanks, Dan

>Dan,

>A solution I have used is to bend a piece of brass tubing into a horse-shoe
>shape and epoxy it (legs in) to a ply block attached to the firewall near
>the muffler cut-out so that the cowl will clear it on removal.  Cut out
>about half the curved external protruding section of the horse-shoe and
>join the two sections with fuel tube.  Connect one internal leg to the tank
>overflow and the other to the muffler pressure ***.

>To refuel simply disconnect the fuel tube joining the two external curved
>tubes.  The fuel overflow will run out one of them.  Replace the tubing
>before flying.

>--
>Ian Mitchell


Arc
 
 
 

Help with in-cowl muffler

Post by Brett Jaff » Wed, 21 May 1997 04:00:00


Hmm.  Is it just me, or are these solutions to this problem a case of over
engineering?  I've had a cowled-in .46SF with a Pitt's muffler for about 5
years, and never even thought there needed to be a solution to this problem.  
Just let the overflow run out the muffler.  Honest, it works!


Quote:

>Dan
>   I have used two Kwik-fill valves one on the fuel line to fill and one on
>the muffler pressure
>for overflow.Worked for me just a little on the expensive side.Used it in a
>GP Cherokee.
>Good luck.



>> I am (slowly) building a Great Planes P-51 with an OS 46FX
>> engine.  I am using a Slimline Pitts-style muffler, so the
>> engine will be mostly enclosed except for cooling holes.

>> This is the first cowled plane I have built, so I'm on new
>> ground here.  The otherwise good Great Planes instructions
>> aren't telling me what I need to know.

>> So I'll throw this to the 'Net wizards.  I was planning to use
>> a Du-Bro #334 Kwik-Fill fuel valve on the side of the fuselage
>> near the fuel tank.  I assume that will let me refuel without
>> pulling any fuel lines off the engine or muffler.  But what
>> happens when the tank is full?  Normally, I am used to seeing
>> the fuel line to the engine (which is pulled off during fueling),
>> spit fuel when the tank is full.  How should this work now?

>> Do I need to run a tank vent line down and out the bottom of
>> the fuselage?  Is that a third line coming out of the tank?
>> As you can see, I'm stuck here.  I'd appreciate any help you
>> can provide.  An e-mail directly to me would be the best way to
>> respond.

>> --Thanks, Dan

__________________________________________________________________________
Brett Jaffee

http://www.earthlink.net/~jaffee



__________________________________________________________________________

 
 
 

Help with in-cowl muffler

Post by Bob Burril » Wed, 21 May 1997 04:00:00


Quote:

> Just let the overflow run out the muffler.  Honest, it works!

And I can hear a definite difference in pitch of the pump when it starts
to go out the muffler pressure line.

Thanks,
rb

 
 
 

Help with in-cowl muffler

Post by Brett Jaff » Sat, 24 May 1997 04:00:00


Also, with the Slimline, you can hear a sort of hollow wind sound coming out
of the pipes a few seconds before they overflow (with a hand crank pump, at
least).



Quote:

>> Just let the overflow run out the muffler.  Honest, it works!

>And I can hear a definite difference in pitch of the pump when it starts
>to go out the muffler pressure line.

>Thanks,
>rb

__________________________________________________________________________
Brett Jaffee

http://www.earthlink.net/~jaffee



__________________________________________________________________________