Author: "David Domeier" <davidd010@...> Time: Fri Oct 25, 2002 8:39 pm PDT Link
I am building the 7A but since the 7 and 9 have the same
fuselage, perhaps some of you will share your thoughts on the
subject of this message.
ÊÊÊÊ
I installed today the fuel vent system from the forward fuselage to
the AN832 fitting through the fuselage wall just forward of the fuel
tank bracket. From that AN832 the vent line makes a short run to
the fuel tank fitting.
In reviewing the plan it shows the main fuel line as a continuous
run from the tank fitting to the fuel valve like a snake making a
number of turns through the tank support bracket, through the
fuselage side wall, around the main gear structure and finally
arriving at the valve.
With some 3000 RV's flying, certainly many guys have performed
this task. But it would seem much easier and quicker to use a
bulkhead union (AN832, AN833 or AN837)at the fuselage wall as
is the case with the vent line. The 2 short lines of tubing to and
from the bulkhead fitting would be easy and quick to make and
install compared to bending, just right, one long tube.
The only reason I can think of for not doing this is the possibility
of tank movement between the wing and fuselage causing
stress on the short line. But that doesn't seem possible with the
tank secured forward on the tank support bracket.
I am looking for critique. Can anyone think of a reason not to
use a bulkhead fitting at the fuselage wall for the fuel line?
(other than pure RV aesthetics).
dd
Author: "Clay R" <clayr_55@...> Time: Fri Oct 25, 2002 9:33 pm PDT Link
Believe it or not, I just returned from the garage to ask almost the
very same question regarding the fuel plumbing.
I just finished the left side vent tube.. which took hours to get
just right... and the vent tube on the RV9A plans goes through a
rubber grommet in the fuselage side skins. However, the fuel tube
also goes through a rubber grommet in the side skins.
My question is regarding that fuel tube that goes from the fuselage
side through two 90 degree bends back behind and through the gear
mounts, through a couple more grommets and then a couple of complex
bends to the fuel valve. This looks almost impossible to bend and
fit due to the route, and it looks like it is going to have to be
bent in place somehow. How in the world am I going to get a bending
and flaring tool in there? (I don't even want to think about the
wing attach bolts with all that tubing going by)
Plus, on my QB fuselage, where the fuel tube passes through the
grommets in the bracket attached to the spar, the gear mount is
clearly in the way! It appears I'll have to move the holes to clear
the gear mount tubing! I'll post a photo in the photo section to
illustrate.
Ideas or encouragement please!
--Clay
--- In RV-9A@y..., "David Domeier" <davidd010@e...> wrote:
> I am building the 7A but since the 7 and 9 have the same
> fuselage, perhaps some of you will share your thoughts on the
> subject of this message.
>
> ÊÊÊÊ
> I installed today the fuel vent system from the forward fuselage
to
> the AN832 fitting through the fuselage wall just forward of the
fuel
> tank bracket. From that AN832 the vent line makes a short run to
> the fuel tank fitting.
>
> In reviewing the plan it shows the main fuel line as a continuous
> run from the tank fitting to the fuel valve like a snake making a
> number of turns through the tank support bracket, through the
> fuselage side wall, around the main gear structure and finally
> arriving at the valve.
>
> With some 3000 RV's flying, certainly many guys have performed
> this task. But it would seem much easier and quicker to use a
> bulkhead union (AN832, AN833 or AN837)at the fuselage wall as
> is the case with the vent line. The 2 short lines of tubing to
and
> from the bulkhead fitting would be easy and quick to make and
> install compared to bending, just right, one long tube.
>
> The only reason I can think of for not doing this is the
possibility
> of tank movement between the wing and fuselage causing
> stress on the short line. But that doesn't seem possible with the
> tank secured forward on the tank support bracket.
>
> I am looking for critique. Can anyone think of a reason not to
> use a bulkhead fitting at the fuselage wall for the fuel line?
> (other than pure RV aesthetics).
>
> dd
Author: Matt Burch <mcb@...> Time: Sat Oct 26, 2002 5:51 am PDT Link
At 4:33 AM +0000 10/26/02, Clay R wrote:
>My question is regarding that fuel tube that goes from the fuselage
>side through two 90 degree bends back behind and through the gear
>mounts, through a couple more grommets and then a couple of complex
>bends to the fuel valve. This looks almost impossible to bend and
>fit due to the route, and it looks like it is going to have to be
>bent in place somehow. How in the world am I going to get a bending
>and flaring tool in there?
Clay,
When I redid the fuel system in my 9A I faced similar problems. What I ended up doing was to put a union fitting in each line, between the inner and outer brackets that attach to the spar. This let me make up the funny S-shaped piece separately and snake it through the gear mount, and then attach it the other funny shaped piece that goes to the fuel selector. The spot where it passes through the fuselage side still uses rubber grommets, so when the wing flexes the tubes aren't stressed at that point. In my airplane I have an open-loop fuel return system which requires two fuel lines per tank, so this all got pretty hairy. My website is down right now so I'll attach some photos to show you how it turned out. Good luck!
mcb
--
------------------------------------------------------------------------
Matt Burch | "If it's not on fire, it's a software problem."
mcb@s... | http://www.ambrosiasw.com/~mburch/
------------------------------------------------------------------------
[Non-text portions of this message have been removed]
Author: "David Domeier" <davidd010@...> Time: Sat Oct 26, 2002 7:02 am PDT Link
"I just finished the left side vent tube.. which took hours to get
just right... and the vent tube on the RV9A plans goes through a
rubber grommet in the fuselage side skins."
Isn't that interesting. The RV7A plan has an AN832 fitting
through the fuselage wall for the vent line. Since the 7 plan is
after the 9 plan, maybe Van's decided the fitting is a better
idea.(?)
Thanks for the reply.
dd
Author: "rvbuilder2002" <smcdaniels@...> Time: Sun Oct 27, 2002 8:31 am PST Link
--- In RV-9A@y..., "David Domeier" <davidd010@e...> wrote:
> "I just finished the left side vent tube.. which took hours to get
> just right... and the vent tube on the RV9A plans goes through a
> rubber grommet in the fuselage side skins."
>
> Isn't that interesting. The RV7A plan has an AN832 fitting
> through the fuselage wall for the vent line. Since the 7 plan is
> after the 9 plan, maybe Van's decided the fitting is a better
> idea.(?)
>
> Thanks for the reply.
>
> dd
No... I think someone didn't look at the drawings carefully enough.
The fuel system is the same for both models. The reason a bulkhead
fitting wasn't used for the main fuel line is that it is a straight
shot directly out of the fuselage. The prepositioned hole in the
fuse. will directly line up with the fitting on the tank. Also the
RV-7 and RV-9 have different wings which results in a different cord
length of the tanks. Which puts the wing leading edge at a different
point on the fuse. Which puts the vent fitting at a different point,
etc.,etc. This is one reason why a fitting was used for the vent(to
allow you to custom fit a seperrate line to the tank). The other is
that the vent line has to make a sharp 90 deg. turn...hard to do in
tubing alone.
It is correct that the mainb lines must be fabricated in place buit
it is not that difficult since the outboard brackets on the front of
teh centersection can be unscrewed and removed.
The main issue is that extra joints are potential leaks. After you
maintain an airplane for a while you find that minimizing that
potential is worthwhile.
Scott McDaniels
Author: "David Domeier" <davidd010@...> Time: Sun Oct 27, 2002 11:14 am PST Link
Scott,
On the 7A the main fuel line does not go through the fuselage
straight to the tank fitting. It turns 90¡ forward outside the
fuselage, goes through a lightning hole in the fuel tank attach
bracket, curves upward and finally enters the fuel tank.
Obviously, the 9 plan is much better in this area and I agree, the
main fuel line is a non event if it goes straight to the tank
fitting.
dd
Incidently, where the 7A fuel vent lines goes though the fuselage
with a AN832, it is not to accomodate a sharp turn. The 832 is
straight. So go figure, some things are what they are without
much logic.
--- In RV-9A@y..., "rvbuilder2002" <smcdaniels@j...> wrote:
> --- In RV-9A@y..., "David Domeier" <davidd010@e...> wrote:
> > "I just finished the left side vent tube.. which took hours to
get
> > just right... and the vent tube on the RV9A plans goes through
a
> > rubber grommet in the fuselage side skins."
> >
> > Isn't that interesting. The RV7A plan has an AN832 fitting
> > through the fuselage wall for the vent line. Since the 7 plan is
> > after the 9 plan, maybe Van's decided the fitting is a better
> > idea.(?)
> >
> > Thanks for the reply.
> >
> > dd
>
> No... I think someone didn't look at the drawings carefully
enough.
>
> The fuel system is the same for both models. The reason a
bulkhead
> fitting wasn't used for the main fuel line is that it is a straight
> shot directly out of the fuselage. The prepositioned hole in the
> fuse. will directly line up with the fitting on the tank. Also the
> RV-7 and RV-9 have different wings which results in a different
cord
> length of the tanks. Which puts the wing leading edge at a
different
> point on the fuse. Which puts the vent fitting at a different
point,
> etc.,etc. This is one reason why a fitting was used for the
vent(to
> allow you to custom fit a seperrate line to the tank). The other
is
> that the vent line has to make a sharp 90 deg. turn...hard to do
in
> tubing alone.
>
> It is correct that the mainb lines must be fabricated in place
buit
> it is not that difficult since the outboard brackets on the front
of
> teh centersection can be unscrewed and removed.
>
> The main issue is that extra joints are potential leaks. After you
> maintain an airplane for a while you find that minimizing that
> potential is worthwhile.
>
> Scott McDaniels
Author: "brywd" <brywd@...> Time: Sun Oct 27, 2002 4:54 pm PST Link
Hi folks,
When I did mine the spring coil type bender worked the best. I gave
my son some lessons using the bender and the flaring tool and turned
him loose to do the lines. His smaller stature and lack of knowing
that the task was impossible allowed him to do a beautiful job. Of
course I checked everything as he went, but I didn't need to. I'm
convinced that he could build one of these planes with minimal help at
this point. Anyway with lots of patience and a soft touch the lines
can be installed per the drawings. However my kit was an early one and
the brackets on the front of the center section where the fuel and
brake lines went through were shown wrong. I don't know if Van
corrected the drawings or not, but beware. If you drill and put in
the plastic bushings per the prints I believe the larger fuel line
ends up on the bottom when passing through the brackets. This makes it
impossible to get past the gear web weldment with the fuel line.
Check you plans carefully before drilling the brackets.
Good Luck,
Bryan Wood
Finish Kit
--- In RV-9A@y..., "David Domeier" <davidd010@e...> wrote:
> I am building the 7A but since the 7 and 9 have the same
> fuselage, perhaps some of you will share your thoughts on the
> subject of this message.
>
> ÊÊÊÊ
> I installed today the fuel vent system from the forward fuselage to
> the AN832 fitting through the fuselage wall just forward of the fuel
> tank bracket. From that AN832 the vent line makes a short run to
> the fuel tank fitting.
>
> In reviewing the plan it shows the main fuel line as a continuous
> run from the tank fitting to the fuel valve like a snake making a
> number of turns through the tank support bracket, through the
> fuselage side wall, around the main gear structure and finally
> arriving at the valve.
>
> With some 3000 RV's flying, certainly many guys have performed
> this task. But it would seem much easier and quicker to use a
> bulkhead union (AN832, AN833 or AN837)at the fuselage wall as
> is the case with the vent line. The 2 short lines of tubing to and
> from the bulkhead fitting would be easy and quick to make and
> install compared to bending, just right, one long tube.
>
> The only reason I can think of for not doing this is the possibility
> of tank movement between the wing and fuselage causing
> stress on the short line. But that doesn't seem possible with the
> tank secured forward on the tank support bracket.
>
> I am looking for critique. Can anyone think of a reason not to
> use a bulkhead fitting at the fuselage wall for the fuel line?
> (other than pure RV aesthetics).
>
> dd
Author: "Clay R" <clayr_55@...> Time: Sun Oct 27, 2002 7:46 pm PST Link
I finished the plumbing this weekend... whew! Glad that's done.
All the gory details are on the web site, from having to move the
grommets so the fuel line didn't interfere with the gear mounts, to
the installation of the fuel line and the long brake lines.
http://webpages.charter.net/RV9A
See pages 2 and 3 of the fuselage progress.
--Clay R
Author: "rvbuilder2002" <smcdaniels@...> Time: Sun Oct 27, 2002 9:10 pm PST Link
--- In RV-9A@y..., "David Domeier" <davidd010@e...> wrote:
> Scott,
>
> On the 7A the main fuel line does not go through the fuselage
> straight to the tank fitting. It turns 90¡ forward outside the
> fuselage, goes through a lightning hole in the fuel tank attach
> bracket, curves upward and finally enters the fuel tank.
Are you talking about an installation with a flop tube? Since this
is the RV-9 group (non aerobatic) I wasn't even thinking about that
installation. I am quite sure that the "standard" (as supplied in
the kit) system has the line exiting the fuse straight out the side
and onto the fuel pickup tube fitting that is mounted in the fuel
tank access cover. If you are bulding an RV-7 and are using a flop
tube (which I think is a waste of time and money for 99% of the
people that do)then you would want to use a 90 deg fitting to aim the
line fwd towards the front of the tank.
> Obviously, the 9 plan is much better in this area and I agree, the
> main fuel line is a non event if it goes straight to the tank
> fitting.
>
> dd
>
> Incidently, where the 7A fuel vent lines goes though the fuselage
> with a AN832, it is not to accomodate a sharp turn. The 832 is
> straight. So go figure, some things are what they are without
> much logic.
Well if no logic was involved then you can blame me... I am the idiot
that designed the fuel system and spec.ed the parts while building
the RV-9A and the RV-7 prototypes :-)
I may have been caught myself, by forgetting that the two airplanes
have different cord length fuel tanks and I guess that the 90 deg
fitting I was remembering is the one on the RV-9 that turns the fuel
vent line aft through the F-902 bulkhead. My memory is telling me
that the RV-7 has a 90 deg bulkhead fitting also but it goes directly
out the sidewall, not aft through the F-902 bulkhead?
Oh well I guess my mind is stuck in RV-10 mode now.
Scott McDaniels
Author: "David Domeier" <davidd010@...> Time: Mon Oct 28, 2002 9:15 am PST Link
"Well if no logic was involved then you can blame me... I am the
idiot that designed the fuel system and spec.ed the parts while
building the RV-9A and the RV-7 prototypes :-)"
Scott,
When I wrote the email concerning fittings and bending tube, 2 of
the bulkhead fittings got switched in my brain. The fittings are an
832 (straight) aft of the firewall and an 833 (90¡ angle) through
to the tank. There's nothing wrong with your logic function, it's my
memory that's failing. You spec.ed them correctly.
Also, the left side of the 7A plan has the fuel line going a straight
to the tank. So the original premise of asking for feed back on
bulkhead fittings was a waste of eveyone's time. No one on the
9 is doing the flop tube and neither am I. (READ the plan, idiot!)
I'm on this forum because I started building the 9A, completed
the empennage and then decided I wanted to use a 180 hp
engine so switched to the 7A and then became a Eggenfellner
convert and ended up with 160 hp engine anyhow and
sometimes wish it were still a 9 (for its flying qualities.)
So how's that for convoluted logic?
dd
Retired (retarded)
Author: "Votuc.com" <guy@...> Time: Mon Oct 28, 2002 9:46 am PST Link
You tell em Scott :>) The neat thing about design....So many ways to do things.
Guy
----- Original Message -----
From: "David Domeier" <davidd010@e...>
To: <RV-9A@yahoogroups.com>
Sent: Monday, October 28, 2002 12:15 PM
Subject: [RV-9A] Re: Fuel Plumbing Thoughts
"Well if no logic was involved then you can blame me... I am the
idiot that designed the fuel system and spec.ed the parts while
building the RV-9A and the RV-7 prototypes :-)"
Scott,
When I wrote the email concerning fittings and bending tube, 2 of
the bulkhead fittings got switched in my brain. The fittings are an
832 (straight) aft of the firewall and an 833 (90¡ angle) through
to the tank. There's nothing wrong with your logic function, it's my
memory that's failing. You spec.ed them correctly.
Also, the left side of the 7A plan has the fuel line going a straight
to the tank. So the original premise of asking for feed back on
bulkhead fittings was a waste of eveyone's time. No one on the
9 is doing the flop tube and neither am I. (READ the plan, idiot!)
I'm on this forum because I started building the 9A, completed
the empennage and then decided I wanted to use a 180 hp
engine so switched to the 7A and then became a Eggenfellner
convert and ended up with 160 hp engine anyhow and
sometimes wish it were still a 9 (for its flying qualities.)
So how's that for convoluted logic?
dd
Retired (retarded)
To unsubscribe from this group, send an email to:
RV-9A-unsubscribe@egroups.com
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/