SR post mods and a question

[Mike Kimball]

Hi all,

Thought I'd pass on a modification thought up by fellow SR builder, Rob
Merdes, here in Fairbanks that I have done on my SR too. He and I were both
pondering the design of the gear box, front post assembly, and front wing
spar carrythrough structure. We could see a great deal of strength in the
gear box area and the carrythrough, but the two structures were tied
together with what appeared to be a much weaker front door post structure.
Soooo, Rob decided to replace the original door post channels with 2 X 1 X
1/8 inch aluminum channel. They fit just right, requiring only a slight
rebending of the door post channel spacer flanges to fit between the thicker
post channels. I liked the idea and did it on mine too. Now, the square
assembly formed by the gear box, door posts and front spar carrythrough is
hell for stout! Combined with the V-brace, and the front spar carrythrough
mod for the 3500 upgrade, there will be a lot more strength leading up to my
firewall which will have a heavier than normal engine up front. Unnecessary
on an already stout airframe - probably. Overkill - most likely. Perhaps
even ill advised if the stronger structure causes stresses intended to be
absorbed in this area to be passed on to other areas. But hey, it's an
experimental airplane, seems like a nice area to strengthen, especially
given my engine choice, and I am the President and CEO of Mike Kimball
Aircraft Manufacturing, Inc.

On another subject, does anyone know any tricks for drilling a hole in the
fuel tanks without leaving a bunch of metal shavings inside. Magnesium
torch? Phaser pistol maybe? I forgot to install a fitting for fuel return
which I'll need for the fuel injection used by the LS-1/LS-6 Chevy V8. Can
the fuel return fitting be on the bottom of the tank instead of the top?
The reason I ask that is that I have an extra fitting in one tank already
because I had already drilled the fuel outlet near the trailing edge of the
root rib before I got the Service Bulletin telling me to move it forward.
To keep the fuel balanced, I still need to drill an extra hole in the other
wing though. I can probably snake a hose connected to my shop vac down
through the fuel filler to try and get shavings out? That plus the finger
strainer and fuel filter might protect me. Whattayathink?

Mike Kimball
SR #044




-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[LisaFly99]

In a message dated 10/17/01 9:30:39 PM Central Daylight Time, agt@mosquitonet.com writes:

On another subject, does anyone know any tricks for drilling a hole in the
fuel tanks without leaving a bunch of metal shavings inside

MIKE
How big of a hole? And old trick for tapping threads is to pack the flutes with grease or petroleum jelly and go slow. It will catch most of the chips and shavings. Might possibly be done with a drill bit also, at slow speeds. If it's hole saw size you can do the same. Go slow clean often repack.
Phil&Lisa Smith #460R N414D

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[Bob Patterson]

Hi Mike !

It is acually VERY IMPORTANT that you DON'T have the fuel return
at the TOP of the tank ! This has proven to be a problem area for
others - the fuel tumbling down into the tank builds up static electricity,
and, if there's enough air in the tank to make an explosive mixture -

%^$%&^&^ !!!!!

Having the return outlet at least half-way down, or at the bottom
is the best place for it. You will likely be OK with the Shop-Vac,
if it is running while you drill. (I'm assuming you've never had
fuel in the tank - otherwise, the sparks from the drill motor will
give unpleasant results !! )

As for changing the primary structure - you know you're on your
own there ! A couple of thoughts, though - first, the factory is always
available to provide comments on this kind of change, and might spare
you grief. Any change may also effect your resale value ...

We have seen mods that appeared to be sensible, that, when
analyzed, produced completely unacceptable load paths that greatly
reduced the safety of the aircraft. Not saying what you did is a
problem, only that it doesn't hurt to ask !!

As you say, sometimes these beef-ups move the loads to another
area where they produce more damage in a mishap. Wayne calls this
"The Bigger Band-Aid Syndrome !!" ;-)

......bobp

-------------------------------orig.-----------------------------------
At 04:57 PM 10/17/01 -0800, you wrote:

*-------------------------------------------------------------------------*
The list archives are located at:
http://rebel:builder@www.dcsol.com:81/default.htm
*-------------------------------------------------------------------------*
Hi all,

Thought I'd pass on a modification thought up by fellow SR builder, Rob
Merdes, here in Fairbanks that I have done on my SR too. He and I were both
pondering the design of the gear box, front post assembly, and front wing
spar carrythrough structure. We could see a great deal of strength in the
gear box area and the carrythrough, but the two structures were tied
together with what appeared to be a much weaker front door post structure.
Soooo, Rob decided to replace the original door post channels with 2 X 1 X
1/8 inch aluminum channel. They fit just right, requiring only a slight
rebending of the door post channel spacer flanges to fit between the thicker
post channels. I liked the idea and did it on mine too. Now, the square
assembly formed by the gear box, door posts and front spar carrythrough is
hell for stout! Combined with the V-brace, and the front spar carrythrough
mod for the 3500 upgrade, there will be a lot more strength leading up to my
firewall which will have a heavier than normal engine up front. Unnecessary
on an already stout airframe - probably. Overkill - most likely. Perhaps
even ill advised if the stronger structure causes stresses intended to be
absorbed in this area to be passed on to other areas. But hey, it's an
experimental airplane, seems like a nice area to strengthen, especially
given my engine choice, and I am the President and CEO of Mike Kimball
Aircraft Manufacturing, Inc.

On another subject, does anyone know any tricks for drilling a hole in the
fuel tanks without leaving a bunch of metal shavings inside. Magnesium
torch? Phaser pistol maybe? I forgot to install a fitting for fuel return
which I'll need for the fuel injection used by the LS-1/LS-6 Chevy V8. Can
the fuel return fitting be on the bottom of the tank instead of the top?
The reason I ask that is that I have an extra fitting in one tank already
because I had already drilled the fuel outlet near the trailing edge of the
root rib before I got the Service Bulletin telling me to move it forward.
To keep the fuel balanced, I still need to drill an extra hole in the other
wing though. I can probably snake a hose connected to my shop vac down
through the fuel filler to try and get shavings out? That plus the finger
strainer and fuel filter might protect me. Whattayathink?

Mike Kimball
SR #044


*-------------------------------------------------------------------------*
You have received this message because you have subscribed to the
murphy-rebel mailing list.
To unsubscribe from this list, send an e-mail to: list-server@dcsol.com
with "unsubscribe murphy-rebel" in the body of the message.
For assistance contact mike.davis@dcsol.com
*-------------------------------------------------------------------------*

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[klehman]

Mike
Have you considered a separate header tank to eliminate the return to
the main tanks? You can feed it from both wing tanks all the time to
eliminate fuel (mis)management. Some guys use a small half gallon tank
forward of the firewall although I like it a little larger or cool air
blowing on it. The return port does not need to be huge as a little
resistance helps keep bubbles from forming in the line. You want the
return port positioned so any bubbles do not get into the main fuel
outlet. Some guys claim letting the return fuel run down a slope or the
side of the tank helps the bubbles separate. I don't know about that but
the return fuel is warmer so bubbles do like to form in it.
Ken

Mike Kimball wrote:

Hi all,
snip
On another subject, does anyone know any tricks for drilling a hole in the
fuel tanks without leaving a bunch of metal shavings inside. Magnesium
torch? Phaser pistol maybe? I forgot to install a fitting for fuel return
which I'll need for the fuel injection used by the LS-1/LS-6 Chevy V8. Can
the fuel return fitting be on the bottom of the tank instead of the top?
The reason I ask that is that I have an extra fitting in one tank already
because I had already drilled the fuel outlet near the trailing edge of the
root rib before I got the Service Bulletin telling me to move it forward.
To keep the fuel balanced, I still need to drill an extra hole in the other
wing though. I can probably snake a hose connected to my shop vac down
through the fuel filler to try and get shavings out? That plus the finger
strainer and fuel filter might protect me. Whattayathink?

Mike Kimball
SR #044

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[Mike Kimball]

I was under the impression that a substantial amount of fuel is returned to
the tanks with modern automotive fuel injection systems. Plus, wouldn't the
header tank already be full if it is being continuously supplied from the
main tanks? Where would the fuel being returned by the fuel injection
system go?

Mike


-----Original Message-----
From: murphy-rebel@dcsol.com [mailto:murphy-rebel@dcsol.com]On Behalf Of
klehman
Sent: Friday, October 19, 2001 4:54 AM
To: murphy-rebel@dcsol.com
Subject: Re: SR post mods and a question


Mike
Have you considered a separate header tank to eliminate the return to
the main tanks? You can feed it from both wing tanks all the time to
eliminate fuel (mis)management. Some guys use a small half gallon tank
forward of the firewall although I like it a little larger or cool air
blowing on it. The return port does not need to be huge as a little
resistance helps keep bubbles from forming in the line. You want the
return port positioned so any bubbles do not get into the main fuel
outlet. Some guys claim letting the return fuel run down a slope or the
side of the tank helps the bubbles separate. I don't know about that but
the return fuel is warmer so bubbles do like to form in it.
Ken

Mike Kimball wrote:

Hi all,
snip
On another subject, does anyone know any tricks for drilling a hole in the
fuel tanks without leaving a bunch of metal shavings inside. Magnesium
torch? Phaser pistol maybe? I forgot to install a fitting for fuel

return

which I'll need for the fuel injection used by the LS-1/LS-6 Chevy V8.

Can

the fuel return fitting be on the bottom of the tank instead of the top?
The reason I ask that is that I have an extra fitting in one tank already
because I had already drilled the fuel outlet near the trailing edge of

the

root rib before I got the Service Bulletin telling me to move it forward.
To keep the fuel balanced, I still need to drill an extra hole in the

other

wing though. I can probably snake a hose connected to my shop vac down
through the fuel filler to try and get shavings out? That plus the finger
strainer and fuel filter might protect me. Whattayathink?

Mike Kimball
SR #044

** To unsubscribe, send e-mail to list-server@dcsol.com with **
** UNSUBSCRIBE MURPHY-REBEL in the message body on a line by itself **
** Archives located at http://rebel:builder@www.dcsol.com:81/default.htm **
** To contact the list admin, e-mail mike.davis@dcsol.com **




-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[klehman]

Mike
The idea of the header tank is that the fuel pumps feed from the header
and all the return fuel goes back to the header. The main tanks merely
keep the header full. Some guys don't even vent the header but mine will
be vented back to the main tank cross vent to make absolutely certain
that vapour can't build up. Yes there is a substantial amount of return
fuel at low power settings but generally a smaller diameter line is
used. I am using a 1/4" return line on my ej22, same as in the Legacy
car. I believe most pumps are sized to pump at least 50% more fuel than
the engine can burn at max power and it is common to use two pumps for
takeoff.
If you don't use a header tank, most guys seem to use a dual fuel
selector (Andair makes a somewhat pricey one) so that the return fuel is
sent back to the same tank you are feeding from. It really isn't
practical to feed from both tanks simultaneously unless you use a header
tank. It also keeps the efi system from picking up slugs of air and you
can put a sensor in it to warn you if it is not full, which in my case
makes it kind of a 2 gallon reserve tank. As well I don't have to worry
about sudden silence if I use a prolonged sideslip on final while low on
fuel and feeding from the downwing tank. It has been known to happen.
Ken

Mike Kimball wrote:

I was under the impression that a substantial amount of fuel is returned to
the tanks with modern automotive fuel injection systems. Plus, wouldn't the
header tank already be full if it is being continuously supplied from the
main tanks? Where would the fuel being returned by the fuel injection
system go?

-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------

[Mike Davis]

Mike, here is a site with good pictures and discussion about installing a
header tank for a fuel injection system. It's an RV, but the fuel system
should be the same.

http://www.sdsefi.com/rv5.htm

Mike

----- Original Message -----
From: "Mike Kimball" <mkimball@gci.net>
To: <murphy-rebel@dcsol.com>
Sent: Friday, October 19, 2001 3:32 PM
Subject: RE: SR post mods and a question

I was under the impression that a substantial amount of fuel is returned

to

the tanks with modern automotive fuel injection systems. Plus, wouldn't

the

header tank already be full if it is being continuously supplied from the
main tanks? Where would the fuel being returned by the fuel injection
system go?

Mike


-----Original Message-----
From: murphy-rebel@dcsol.com [mailto:murphy-rebel@dcsol.com]On Behalf Of
klehman
Sent: Friday, October 19, 2001 4:54 AM
To: murphy-rebel@dcsol.com
Subject: Re: SR post mods and a question


Mike
Have you considered a separate header tank to eliminate the return to
the main tanks? You can feed it from both wing tanks all the time to
eliminate fuel (mis)management. Some guys use a small half gallon tank
forward of the firewall although I like it a little larger or cool air
blowing on it. The return port does not need to be huge as a little
resistance helps keep bubbles from forming in the line. You want the
return port positioned so any bubbles do not get into the main fuel
outlet. Some guys claim letting the return fuel run down a slope or the
side of the tank helps the bubbles separate. I don't know about that but
the return fuel is warmer so bubbles do like to form in it.
Ken

Mike Kimball wrote:

Hi all,
snip
On another subject, does anyone know any tricks for drilling a hole in

the

fuel tanks without leaving a bunch of metal shavings inside. Magnesium
torch? Phaser pistol maybe? I forgot to install a fitting for fuel

return

which I'll need for the fuel injection used by the LS-1/LS-6 Chevy V8.

Can

the fuel return fitting be on the bottom of the tank instead of the top?
The reason I ask that is that I have an extra fitting in one tank

already

because I had already drilled the fuel outlet near the trailing edge of

the

root rib before I got the Service Bulletin telling me to move it

forward.

To keep the fuel balanced, I still need to drill an extra hole in the

other

wing though. I can probably snake a hose connected to my shop vac down
through the fuel filler to try and get shavings out? That plus the

finger

strainer and fuel filter might protect me. Whattayathink?

Mike Kimball
SR #044

** To unsubscribe, send e-mail to list-server@dcsol.com with

**

** UNSUBSCRIBE MURPHY-REBEL in the message body on a line by itself

**

** Archives located at http://rebel:builder@www.dcsol.com:81/default.htm

**

** To contact the list admin, e-mail mike.davis@dcsol.com

**

** To unsubscribe, send e-mail to list-server@dcsol.com with

**

** UNSUBSCRIBE MURPHY-REBEL in the message body on a line by itself

**

** Archives located at http://rebel:builder@www.dcsol.com:81/default.htm

**

** To contact the list admin, e-mail mike.davis@dcsol.com

**




-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------