Message-ID: <19990129082705.5195.qmail@hotmail.com>
From: "don cavers" <drcavers@hotmail.com>
To: lancair.list@olsusa.com
Subject: Re: 13B cooling
Date: Fri, 29 Jan 1999 00:27:00 PST
Mime-Version: 1.0

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>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 
myse=
>lf.
>I like that scoop myself. Good choice. What I couldn't see from the 
pics =
>was
>the distance between the upper lip and the fuselage (for all 
discussions,
>lets assume the scoop is mounted on the belly and not on the hood of a 
ca=
>r.)
>so I went with 15711. Do me a favour and measure that and send it to 
me.
>(Pics of both attached.) I have 15715 and I've started cutting but I 
may =
>go
>get 15711. It would fit the LC20 belly better and looks like there 
would =
>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 
rad =
>is
>11" thick and looks almost like a solid mass.
>
>Jim Mosur has 2 rads, 12x14x2", identical in every way, mounted in 
parall=
>el.
>In practice, one rad does most of the work as we found out through high 
R=
>PM
>ground running. After about 5 mins of near full throttle running, his 
rig=
>ht
>rad was hot (as expect) but the left was somewhere between warm to 
stone
>cold, depending where you touched the core. We installed a variable 
ball
>valve in the line going to the hot rad and closed it down by 1/3 - 1/2. 
N=
>ow
>both rad get good and warm and the operating temps went down!!! Looking 
a=
>t
>the plumbing with the good old mark 4 eyeball, there is no reason for 
the
>flow to favour one rad over the other. Checking the rads themselves, 
ther=
>e
>no difference in flow between the rads either. The cold rad has a 2" 
radi=
>us
>90degree bend hose in the line whereas the warm rad doesn't do any 
major
>bends but the hot rad has a longer distance to run. Doesn't make sense 
I
>know, but it does suggest if you're going to put the rads in parallel, 
yo=
>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 
sound
>like a problem for 7/8" lines. Parallel may be your only choice if 
you're
>sticking to those rads. Personally, I would go for a custom fabricated 
ra=
>d
>(which what I plan on doing). If you add all the time and expense I've 
go=
>ne
>through doing radiators, now for the 4th time, you can understand my 
reas=
>ons
>for designing for overkill and spending the extra money. I don't want 
to =
>do
>it a 5th time. Unfortunately, there hasn't been much written on the 
subje=
>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 
i=
>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 
o=
>ut
>in 2 hours as a result of high-speed air going through them 
continuously.
>From what I've heard, the same happened to the other installations as 
wel=
>l.
>Give it a try, but check them after every flight. I know they work on 
car=
>s
>and motorcycles. I have 500,000 miles on Goldwings and I've never 
replace=
>d a
>fan. The temp switch yes but never a fan. Don=92t forget the extra 
restri=
>ction
>the fan will cause at flight speeds which is where you want the rads to 
b=
>e
>most effective. Ground running develops probably no more than 20 HP 
compa=
>red
>to 150 in flight. If you're ever stuck on the ground waiting for 
clearanc=
>e
>and the system is getting hot, shut it off. The rotary will start first 
t=
>ime
>every time if your other systems are good. I.e., no problems with 
vapour
>lock.
>
>I'm going to put the cowl flap on the scoop as done with the P-51. I'm 
no=
>t
>sure what you mean by mounting it on the fuselage. A good push-pull 
cable
>should do the job nicely. I was thinking of something like a mixture 
cabl=
>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 
measures
>>17 1/2 x 8 1/2 inside. Cost $248. Can. in Vancouver. I've picked the 
all
>>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 
cooling.
>>Two will mount nicely and it is easy enough to add to if need be. In 
the
>>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 
will
>>be set to draw air through the two rads on demand or on a temp sensor 
as
>>is done on a lot of vehicles these days. The series vs. parallel 
plumbin=
>g
>>question concerns me somewhat because of the lower flows of these 
rads.
>>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. 
That
>>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 
few
>>days and should be running by Friday.
>>Don
>>
>>
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>
>
>


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