Ed,
Thanks for the reply, now I believe I'll go with a smaller
header tank and make it aluminum or maybe go with fiberglass and use a cooler
on the return line, save a few pounds in the process. Just how much heat is
picked up in the fuel on the return? The Mazda fuel pump assembly has
the return going in a few inches from the pick-up for the pump and I suppose
there are no fuel heat related problems on the car.
You talk about a boost pump. What type and how is it
plumbed in to the fuel system? (Maybe you get the idea I like to copy from
successful people?)
Wendell
Fuel system design is certainly a critical area and a lot of
thought needs to be given it.
I went against the concept of large header tanks and have
one that holds approx 32 oz or one pint. I have it mounted on the
engine side of FW (would change that) and at the lowest point. After my
pressure regulator, my return fuel dumps into this tiny header tank.
Many of today's EFI automobiles now use a "returnless" fuel
system by controlling the fuel pressure as needed to prevent vapor lock.
I view my tiny header as sort of an in-between a header than and no header
tank {:>).
I do have blast tubes of cooling air going to it and I did
have fuel percolation on the ground before putting the tubes in.
However, the boost pump (6 psi) immediately squished any that occurred.
Having been flying with it in the sunny South for almost 10
years.
My rational was that IF your larger header tanks does get
filled with hot fuel, its going to take a long time to burn that hot fuel off
and get new cooler fuel. My pint gets replenished at flight power
settings so quickly that heat is not an issue. A long idle on a hot day
could cause some percolation, but since I always take off with boost pump on,
its never been an issue.
Be oh-so-careful in design of your fuel system - needless to
say, but will anyhow.
Ed
----- Original Message -----
Sent: Saturday, August 25, 2007 9:59
PM
Subject: [FlyRotary] Re: need
help
Thanks Ed and Charlie,
You both got the same answer, I
think the 1.8 gal. estimate came from my first mock-up and it was 14 in.
instead of 15. In some of my calculations I did get 2.0 +something as
an answer. Now how much sump tank volume is really needed? I
think Perry Mick uses one slightly over a gallon. If one gallon is
sufficient, then I can save 6 pounds of usually unused fuel.
I regret hearing about George
Graham, I was hoping to meet him, he sent a drawing of his cooling set-up
and was always ready to help.
Wendell
You can look at your tank as composed of two boxes
(actually one and 1/2 boxes). 1st box is 3.75" x 6" x 15" =
337.5 cubic inches.
A second box is 3.75 " x (11-6)" x 15" = 281.25 Cubic
inches but you really only have 1/2 of this box, so triangular
section volume = 1/2 (rectangular section) volume =
281.25 * 1/2 = 140.625 cubic inches
So total volume = volume of 1st box (337.5 )+ 1/2 volume
of second box (140.625) = 478.125 cubic inches or 2.07 US
Gallons
Ed
----- Original Message -----
Sent: Saturday, August 25, 2007
1:19 PM
Subject: [FlyRotary] Re: need
help
Thanks for the responses to my requests.
I wasn't to go John Slade's route and try to put in an air
conditioner and the lines need to take 250 to 300 psi. The
larger return line should only see about 175 psi on a hot tarmac
(engine off) and the feed line will see up to 275 psi (assuming a
inefficient condenser) on a hot day.
Finding a place for the condenser is the main problem as I see
it.
I'll
look up Mazdatrix for the exhaust studs. I hoped someone knew
the exact size so they could be purchased locally.
Here
is a math problem for you brain types (all rotary head but me) -how
much fuel will a tank hold that is 3.75 in. tall, 15 in. long, 11
in.deep on the bottom, top is 6 in. deep then slopes to zero at the
front? I think it is about 1.8 gal.
___6in._
| \
|_________\
11in.
Wendell
In a message dated 8/23/2007 8:29:10 PM Pacific Standard Time,
jwvoto@itlnet.net writes:
Hey guys,
I still need help in obtaining the nuts for the exhaust studs
on the 13b. Also, does anyone have working phi ratings for 3003-0
aluminum tubing. Can it withstand 250psi
Wendell
What wall thickness Wendell? .010 thick NO! 1 inch (wall) yes.
Give us an idea of what you are using it for.
Bill Jepson
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