From: "Neil A. Kruiswyk" <neilk@sprint.ca>
To: "don cavers" <drcavers@hotmail.com>
Cc: <lancair.mail@olsusa.com>
Subject: Re: 13B cooling
Date: Sun, 24 Jan 1999 07:53:35 -0500

Don,
Good idea to CC Marv in all this. Shame on me for not thinking of it

lf.
I like that scoop myself. Good choice. What I couldn't see from the

was
the distance between the upper lip and the fuselage (for all

lets assume the scoop is mounted on the belly and not on the hood of a

r.)
so I went with 15711. Do me a favour and measure that and send it to

(Pics of both attached.) I have 15715 and I've started cutting but I

go
get 15711. It would fit the LC20 belly better and looks like there

be
less drag. My scoop lip hangs pretty low below the fuselage.

I wouldn't worry too much about air restrictions in 3 rads. The P-51

is
11" thick and looks almost like a solid mass.

Jim Mosur has 2 rads, 12x14x2", identical in every way, mounted in

el.
In practice, one rad does most of the work as we found out through high

PM
ground running. After about 5 mins of near full throttle running, his

ht
rad was hot (as expect) but the left was somewhere between warm to

cold, depending where you touched the core. We installed a variable

valve in the line going to the hot rad and closed it down by 1/3 - 1/2.

ow
both rad get good and warm and the operating temps went down!!! Looking

t
the plumbing with the good old mark 4 eyeball, there is no reason for

flow to favour one rad over the other. Checking the rads themselves,

e
no difference in flow between the rads either. The cold rad has a 2"

us
90degree bend hose in the line whereas the warm rad doesn't do any

bends but the hot rad has a longer distance to run. Doesn't make sense

know, but it does suggest if you're going to put the rads in parallel,

u
had better find some way to insure equal flow rates between them.

7/8" lines on the motorcycle rads might be a problem. The engine flows
150-160 litres/min at 5000 rpm. I'm no fluid dynamics engineer but

like a problem for 7/8" lines. Parallel may be your only choice if

sticking to those rads. Personally, I would go for a custom fabricated

d
(which what I plan on doing). If you add all the time and expense I've

ne
through doing radiators, now for the 4th time, you can understand my

ons
for designing for overkill and spending the extra money. I don't want

do
it a 5th time. Unfortunately, there hasn't been much written on the

ct
of water cooling an aeroplane that I've been able to find. I'm sure it
exists, what with all the work on WWII heavy metal, but I haven't found

t
yet.

A couple people, including myself, have tried rad fans. I used 2 high
quality muffin fans on my original oil cooler set up. The bearings gave

ut
in 2 hours as a result of high-speed air going through them

From what I've heard, the same happened to the other installations as

l.
Give it a try, but check them after every flight. I know they work on

s
and motorcycles. I have 500,000 miles on Goldwings and I've never

d a
fan. The temp switch yes but never a fan. Don=92t forget the extra

ction
the fan will cause at flight speeds which is where you want the rads to

e
most effective. Ground running develops probably no more than 20 HP

red
to 150 in flight. If you're ever stuck on the ground waiting for

e
and the system is getting hot, shut it off. The rotary will start first

ime
every time if your other systems are good. I.e., no problems with

lock.

I'm going to put the cowl flap on the scoop as done with the P-51. I'm

t
sure what you mean by mounting it on the fuselage. A good push-pull

should do the job nicely. I was thinking of something like a mixture

e
that is fine tune-able and locks.

Ok, I'm all typed out for the moment.... :)

Neil

I've taken the liberty of cc to Marv so he can be in on this loop.

I got the A&A 15715 (don't have the # here to check) scoop that

17 1/2 x 8 1/2 inside. Cost $248. Can. in Vancouver. I've picked the

alu motorcycle rads because they are off 100 HP machines and are very
tough. I would be concerned about overkill using 3 because you have to
get to a point where airflow is too restricted to get efficient

Two will mount nicely and it is easy enough to add to if need be. In

short term I'm not going to glass the scoop on so changes will be easy
to make. One other feature I like on the motorcycle rads is that some
have a small electric fan that could be used when on the ground. It

be set to draw air through the two rads on demand or on a temp sensor

is done on a lot of vehicles these days. The series vs. parallel

g

question concerns me somewhat because of the lower flows of these

What effect will it have if the waterpump is trying to push that water
through the rads in series? I think the flow is such (1 1/2" output)
that there will be no choice but for the flow to utilise both rads.

will be the path of least resistance with 7/8" connections. No?
I'm also planning on a cowl flap. The formula seems to be to have a
range of exhaust airflow from 115% to 150% of air volume in so that is
what I'm aiming for. It is way easier to hinge that flap off the
fuselage but I notice in Mayer's EAA articles the flap is hinged from
the bottom. Do you think it makes any difference?
Definitely interested in any thoughts. I'll have the rads here in a

days and should be running by Friday.
Don


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