Re: Flight Report CHT


fionapple
 

Sky Ranch Engineering manual (1991) page 140 has a table saying
Lycoming 320's require 5.5" drop (105 mph ram, 2500 cubic feet per
minute) to cool at full throttle.

--- In Q-LIST@..., "Sam Hoskins" <sam.hoskins@...> wrote:

Somewhere, I have seen the requirements for pressure drop across the
cylinders. I'm in Topeka right now, but I'll look it up whan I get
home. I
think it may be available in the Sky Ranch engine engineering manual
or in
Sonja Englehart's book. I also think Klaus metioned the use of an
airspeed
indicator in his engine forum last year.

Sam Hoskins
Murphysboro, IL

On Fri, Apr 18, 2008 at 5:53 PM, Mike Dwyer <mdwyer@...> wrote:

Hey Guys,
Thursday Flight.
I'm getting prepared to build a "Sam Plenum" inside my Q200 cowl. I
took a 1/4" tube and secured it at the top of the engine, then did the
same at the bottom. I hooked these tubes to my steam gauge airspeed
indicator. Hey, the Dynon was now my only airspeed instrument. I also
installed CHT on all lower plugs. Thursday I flew around to measure my
pressure differential and CHT's. Well, I goofed up the CHT wiring so
forget that but the airspeed was showing 80 mph pressure on a
climb out
and 105 mph in cruise. At work I translated that with a formula to
give
me inches of water which I think was 5" at 120 mph if I remember
correctly... Anyway when I build the plenum I want maybe the same?
Sam, did you ever measure your before and after pressure?

So after all the testing was done I took the opportunity to do
some big
wing overs, and steep turns over the beach. In the Gulf of Mexico off
Dunedin FL there is a new island growing. The blue water mixes into
many shades of green and blue over the sandy bottom. I found a pod of
11 Dolphins splashing along and did some turns about a point over them
until I started getting dizzy. The great thing was there were no birds
out, no idea why not. Usually I spend 90% of my time watching for
birds. Farther down the beach there were 6 more Dolphins heading
north. About 60 feet behind them was what looked like a small shark,
maybe 1/2 the size of the Dolphins and he was following the Dolphins.
You don't usually see them anywhere near each other. Headed back
to the
airport and landed successfully - didn't break anything so it was
a good
flight.

Friday Flight.
Rewired the CHT probes to a two pole rotary switch. It is much more
accurate to use a good digital volt meter than the crap Westach meter
movements, so that's what I did. There is a table of voltage vs temp
for J type thermocouples so I used that.
OAT 80F
Taxi out
Cyl 1 7.7 mv = 144 C = 291 F
Cyl 2 7.6 mv = 142 C = 288 F
Cyl 3 9.6 mv = 178 C = 352 F
Cyl 4 9.2 mv = 172 C = 342 F

OAT 72F
Post Climb at 2500 RPM
Cyl 1 9.1 mv = 169 C = 336 F
Cyl 2 9.2 mv = 172 C = 341 F
Cyl 3 9.5 mv = 176 C = 348 F
Cyl 4 11.3 mv = 209 C = 408 F

Cruise at 2600 RPM
Cyl 1 9.4 mv = 175 C = 347 F
Cyl 2 9.2 mv = 172 C = 341 F
Cyl 3 9.2 mv = 172 C = 341 F
Cyl 4 10.7 mv = 198 C = 388 F

My crap westach CHT on Cyl 1 top read 300 F the whole time. Maybe from
the top plug to the bottom is 40-50F difference???

So it looks like #4 is hotter than all the rest. That's the front left
cyl. I am currently using the QAC supplied baffels, installed per
plans.
I will report back when I get my new fiberglass plenum on (haven't
built
it yet so it may be a while).

After the testing was done I took the opportunity to do some big wing
overs, and steep turns over the beach. In the Gulf of Mexico off
Dunedin FL there is a new island growing. The blue water mixes
into.......

Tomorrow several of us are heading to Punta Gorda for lunch. The
weather has been perfect here, deep blue skys, a few puffies and great
visibilities.

Fly Safe,
Mike Q200 N3QP
http://mikedwyer.quickieairplanes.org/



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